CN117856407B

CN117856407B - Control system and method for actively balancing battery

Info

Publication number: CN117856407B
Application number: CN202410258744.7A
Authority: CN
Inventors: 黄世蔚
Original assignee: Shenzhen Verdewell Technology Ltd
Current assignee: Shenzhen Verdewell Technology Ltd
Priority date: 2024-03-07
Filing date: 2024-03-07
Publication date: 2024-05-10
Anticipated expiration: 2044-03-07
Also published as: CN117856407A

Abstract

The invention discloses a control system and a method for actively balancing a battery, wherein the system comprises a transformer, N electric cores, an analog-to-digital converter, a main control unit and 2N switch circuits; the N electric cores are divided into i battery packs, and the main control unit is connected with the analog-to-digital converter to collect the voltage of each electric core; the main control unit calculates the average voltage of each battery pack, and controls the wave width modulation duty ratio of the battery pack with the highest average voltage when magnetizing and the wave width modulation duty ratio when discharging so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at the wave width modulation duty ratio which is more than 2a percent; and controlling the battery pack with the lowest average voltage to convert the magnetic energy into the electric energy at a wave width modulation duty ratio which is more than 2a percent so as to realize the active equalization speed which is faster than that of the semi-active equalization technology.

Description

Control system and method for actively balancing battery

Technical Field

The invention relates to the technical field of battery equalization control, in particular to a control system and method for actively equalizing batteries.

Background

Currently, battery energy storage devices have been widely used in applications such as rechargeable automobiles, electric bicycles, electric motorcycles, and household storage systems. The battery energy storage device is mainly connected in series through a plurality of electric storage monomers so as to meet the voltage requirement of a system where the battery energy storage device is located. To date, how to extend the service life of battery energy storage devices is a technical challenge for the emerging development of the battery industry.

In the field of battery equalization control technology, an electric storage cell is also called a battery cell, and a plurality of electric storage cells connected in series are called a battery cell string. The texas instruments (Texas Instruments, TI) in the united states published a number of papers stating that the cell voltage in the battery is imbalanced over time, resulting in reduced battery life, reduced endurance, and increased probability of a combustion explosion. The article demonstrates that the service life of the battery can be prolonged after the battery cells of the battery are balanced, the running endurance of the electric vehicle can be prolonged, and the probability of combustion and explosion danger can be reduced. Thus, the explosion of "equalization techniques" in Battery management systems (Battery MANAGEMENT SYSTEM, BMS) has been driven. In order to realize the ampere-hour electric quantity required by the whole system, a plurality of battery cell strings corresponding to the required ampere-hour electric quantity can be connected in parallel. Due to production process limitations in the battery field, individual performance differences exist for multiple cells in series. The method is characterized in that the capacities and voltages of different battery cells are not completely consistent; particularly, as the number of charge and discharge times increases, the voltage difference between the cells becomes more obvious. If no effective measures are taken, the electricity storage capacity of the battery cell string can be affected, the battery cell can be seriously damaged, and even safety accidents such as explosion and the like can be caused.

In the technical field, battery equalization techniques are divided into two main categories, passive equalization and active equalization. The common passive equalization technology utilizes a resistor to bear the charges released by the high-voltage battery cells so as to match the low-voltage battery cells to improve the performance consistency of the plurality of battery cells, so that the full capacity of a great number of single battery cells in the battery pack can be reduced, and the endurance of the whole battery is further reduced. However, in reality, the biggest problem of inconsistent voltages of the multiple battery cells is that the voltage of the battery cells is low because the internal resistance of the battery cells is increased during discharging, and the battery cells with high internal resistance are increased during subsequent charging. Therefore, the battery core with high internal resistance can stop charging in advance due to high voltage in charging, and the battery core with high internal resistance can stop discharging in advance due to low output voltage due to high internal resistance in discharging. The simple explanation is that the charging is less than other battery cells, and the discharging time is also finished earlier than other battery cells. If the general passive equalization technology on the network understands that a resistor is connected in parallel with a cell with higher internal resistance and higher voltage in the charging process to release the charge energy of the discharge core, the cell with the lowest voltage in the discharging process charges less in the subsequent charging process. The passive equalization can not only improve the endurance, but also obtain the reverse effect. However, many experiments prove that the passive equalization is effective and can improve the endurance of the battery, so that the principle of the real passive equalization is that a resistor is connected in parallel with a battery core with higher charging voltage, namely higher internal resistance, in the process of charging the battery. Experiments prove that the technical key point of passive equalization is that the charging current on the battery cell is shunted to an external parallel resistor, so that the voltage drop of the internal resistance inside the battery cell in charging is reduced, the charging voltage is reduced, and the cut-off charging threshold of the battery cell can be delayed. According to the principle of the real passive equalization, the time of stopping charging of the battery of other battery cells with lower charging voltage is not delayed, but the battery cell with higher charging voltage is charged by using smaller current which is shunted by the parallel resistors, so that the voltage drop of the internal resistance of the battery cell is reduced, and the voltage of an ideal battery of the battery cell reaches the charging stopping voltage, namely the voltage of the charging voltage minus the voltage drop on the internal resistance of the battery cell can be increased. Therefore, according to the real principle of passive equalization, through the passive equalization mode of the parallel resistors of the electric cores, the electric core with higher internal resistance can be charged with more charges so as to charge with smaller current relative to other electric cores, and when the electric core with higher internal resistance reaches the cut-off charging voltage threshold value, the voltage of an ideal battery in the electric core with higher internal resistance is increased, which is the real reason that the passive equalization can improve the endurance. However, the disadvantages caused by the passive equalization technology corresponding to the real principle of passive equalization are consistent with those caused by the passive equalization technology described in general network articles, namely that the charging time of the battery is increased, the temperature of the battery is increased due to the heat generated by the parallel resistors, and the charging current is wasted.

Another technique in the battery equalization technique is active equalization, which is to truly redistribute charges, and compared with passive equalization technique, the active equalization technique does not utilize external parallel resistor shunt to increase the ideal battery voltage of the battery core with high internal resistance in charging. The active equalization technology is utilized, not only for saving energy consumed by external parallel resistors in the passive equalization technology, but also for measuring voltage in an open circuit state that the battery cells are disconnected and charged and discharged, so that the measured battery cell voltage is equal to the internal ideal battery voltage, and the consistency balance of the battery cell voltages is achieved through active equalization under the condition that the battery cell voltage is not influenced by the change of the internal resistance of the battery, so that the endurance of the battery can be truly and effectively improved. Of course, to shorten the charging time, it is necessary to discard some of the ideal implementations, and trade off the way in which the measured voltage is adjusted.

TI provides a series of active equalization schemes to transfer the energy of a cell with higher cell voltage to a cell with lower cell voltage, and specifically realizes active equalization by using a multi-winding transformer as the medium of cell voltage equalization. Since the winding of the transformer generates an inductance when passing current, the inductance z= jwL of the inductance, where w=2pi f, pi is the circumference, f is the frequency, and the inductance is high in impedance at high frequency, a voltage generates a high frequency current in the winding through the high frequency switching circuit, and the inductance of the winding at high frequency is high. Therefore, the winding group can be regarded as a current source, the current source is used for connecting voltage sources with unequal voltages, and the problem that the unequal voltages cannot be connected in parallel can be solved.

In the process of realizing active equalization by taking a transformer as a medium of cell voltage equalization, the voltage of each cell is measured firstly, then the energy of a certain section of higher-voltage cell is converted into magnetic energy in an inductor actively, and then the magnetic energy is converted back to current to charge a certain cell with lower voltage. Since the direction of energy conversion is arbitrarily switched between the cells with different series voltages, a very large bidirectional switch matrix is required, and the switch current is large enough, the active equalization circuit is very complex and expensive.

In order to reduce the cost and complexity of active Balancing, one of the technologies is a method similar to TI, that is, a multi-winding transformer is used as a medium for Balancing the voltages of the cells, the top and Bottom of a cell string are connected to a primary coil, each single cell is connected to a group of secondary coils and a pair of MOS switches to conduct current bidirectionally, when the voltage value of a certain cell is lower than the average voltage value of the cells of all the cells connected in series, the primary winding is magnetized from all the cells connected in series in a flyback manner in the first half period, and then the secondary coil corresponding to the cell with the voltage value of the cell lower than the average voltage value of the cell is magnetized in the second half period, and the magnetizing process is that the cell is charged, which is called Bottom Balancing (Bottom Balancing). When the voltage value of a certain battery cell is higher than the average voltage value of all the series battery cells, the battery cells with the voltage value higher than the average voltage value of the battery cells in the first half period of the flyback mode magnetize the secondary windings of the battery cells, and the primary windings corresponding to all the series battery cells are magnetized in the second half period, and the magnetizing process is that all the battery cells are charged together, which is called Top Balancing (Top Balancing). Specifically explaining the magnetizing process, that is, the battery core is conducted through the switch circuit and the winding, the current direction after conduction is from the battery core to the winding, the current generated by the voltage of the battery core in the winding is gradually increased, and the electric energy is gradually converted into magnetic flux in the magnetic core, that is, the electric energy is converted into magnetic energy. This process of gradually establishing magnetic flux is therefore referred to as "magnetizing". In addition, the magnetic discharging process and the relative magnetizing process are explained specifically, otherwise, in the magnetic discharging process, the battery core is conducted through the switch circuit and the winding, the current direction after conduction flows back to the battery core, and the magnetic flux in the magnetic core is gradually reduced. Therefore, the process of converting this magnetic energy back into current through the winding set and gradually flowing back to the cell is called "demagnetizing".

The bottom balance and the top balance described above reduce the number of switches of the switch matrix proposed by TI by approximately half in a multi-winding transformer. However, the bi-directional switch matrix and control circuitry that controls the magnetizing of a single cell from a secondary winding to a primary winding and the magnetizing of a primary winding from a secondary winding of a single cell is still very complex. Therefore, a plurality of new active balancing methods are generated, namely, a multi-tap winding group transformer is used as a medium for balancing the voltages of the electric cores, all the electric cores are repeatedly and simultaneously magnetized, the method is different from the method that the energy of the electric core with higher electric core voltage is transferred to the electric core with lower electric core voltage through an inductor or a transformer after the electric core voltage is firstly measured and then the electric core with higher electric core voltage is advocated by TI, the new system methods only use the inductance characteristic of the transformer, the tap winding group and the magnetic core firstly conduct the electric core to magnetize the magnetic core under the condition that the high-frequency current belongs to reactive lossless in the inductance reactance, at this time, the energy is mixed together in the magnetic core by magnetic flux, then the mixed magnetic energy is conducted and magnetized in the tap winding group respectively, the electric energy of each single electric core is respectively converted back, the purpose of balancing the voltages of the electric cores is achieved in the energy conversion process, the energy conversion from the single electric core to the single electric core is not controlled, and all the electric cores are naturally balanced. The method can also enable the energy of the original battery core with lower voltage and the energy of the battery core with higher voltage to generate average voltage balance, but the cost and the complexity of the bidirectional switch matrix and the control circuit are much lower than those of the active Balancing proposed by TI, and the method is called semi-active Balancing (SEMI ACTIVE Balancing) for the convenience of understanding of the following description. The semi-active equalization technology (SAB) adopts a mode that the energy of a battery core is repeatedly magnetized to the magnetic core of a multi-tap winding group transformer by a high-frequency MOS switch, then the magnetic energy in the magnetic core is released to each battery core, the complexity of a circuit can be reduced, the principle is that the tap winding group with higher voltage of the battery core generates larger magnetizing current every time when the voltage drop is higher than that of the tap winding group, and when the voltage drop is discharged, the added magnetic fluxes are mixed, the magnetic flux is released to be converted to the current in each tap winding group without considering the voltage difference of each battery core, the magnetic energy is averagely split to each tap winding group of the transformer, the magnetic energy is converted to the current, each battery core is averagely charged to become electric energy, and the energy of the battery core with high voltage can be naturally released to the battery core with lower voltage by repeatedly operating the process. The method avoids the defect of passive equalization Passive balancing, achieves the effect of average distribution of the voltage energy of the battery cells relatively quickly, and the industry acknowledges that the new method also belongs to active equalization.

For example, in chinese patent (CN 201620739208), an embodiment 2 of a battery equalizer made of a multi-winding transformer is a semi-active equalization method, in which it is mentioned that electric energy is generally converted into magnetic energy by using an inductor, and magnetic reset is possibly needed in the conversion of magnetic energy into electric energy, and this patent proposes to solve the problem of magnetic reset of an active equalization system of a multi-winding transformer in a voltage equalizer, so that it is possible to ensure that the voltages of all the batteries are completely consistent after the battery pack reaches equalization stability without adding a special magnetic reset circuit.

At present, some manufacturers have adopted the method of the embodiment 2 in the patent (CN 201620739208) to perform active equalization, but because the patent (CN 201620739208) adopts semi-active equalization, all the electric cores are magnetized together in half of the time regardless of the voltage, the other half of the time is used for magnetizing and releasing the magnetic energy in the magnetic core back to the electric core, no 'active' method is adopted to control the electric core with high voltage to release energy to the electric core with low voltage, only the magnetic core is used as an energy conversion mechanism, the energy can flow mutually naturally, the energy conversion from one electric core to another electric core can not be interfered, the energy conversion from one electric core to another electric core can not be calculated as 'complete active' equalization, and the core focus in the patent (CN 201620739208) is that the magnetizing time is the same as the magnetizing time, that is, the magnetizing and the magnetizing duty ratio is 50%, so that the magnetic reset problem can be avoided.

For example, chinese patent CN202310850593 proposes an active equalization circuit, an equalization controller and an equalization control system, which are also the above-mentioned methods of semi-active equalization, and do not actively control the energy transfer of a single cell to a single cell, but only perform passive equalization naturally, where the equalization controller outputs periodic high-frequency control signals to the nth equalization unit for controlling the first MOSFET switch tube and the second MOSFET switch tube to be alternately turned on and off, and the core emphasis is that gate bias is provided economically and effectively, and in the patent CN202310850593, control timing of MOS switches is also proposed, and complementary time of magnetizing and demagnetizing each takes half is also provided, and an explanation of dead zone control of the timing of the MOS switches is also provided, so that effective adjustment of equalization current and equalization speed of the entire semi-active equalization circuit is achieved.

At present, a great part of technologies in the industry adopt the semi-active equalization, and the semi-active equalization technology particularly emphasizes that the magnetizing and the discharging have to be consistent, and the duty ratio of the magnetizing and the discharging is 50 percent, so that the effect of natural magnetic reset can be achieved.

Therefore, the method comprises the steps of magnetizing electric energy into magnetic flux in a magnetic core by using a multi-tap winding group through high-frequency current to be added in parallel, and then magnetizing the mixed magnetic energy into electric energy to be shunted to the electric core through the high-frequency current, so that the energy of the high-voltage electric core cannot be directly transferred to the electric core with low voltage, the magnetizing current is larger due to the fact that the high-voltage electric core is in direct proportion to the current and the voltage in a magnetizing switch, and the magnetic core is magnetized, because the inductance is very high, the magnitude of the inductance current is irrelevant to the voltage of the electric core, the current can be adaptively recharged to the electric cores with different voltages, so that during the high-frequency charging and discharging, the electric core with high voltage is magnetized out a little more at each time, and the electric energy is slowly released to the electric core with low voltage.

The existing system and method for active balancing of magnetic energy mainly have the following four problems:

the first and the tap winding groups have different wire lengths and are compact, so that the same voltage is not required to generate the same current, and the precision of the tap winding group transformer has great influence on the voltage balance effect;

Secondly, according to experiments, the high-potential battery cell releases energy to the low-potential battery cell, just like water flows to Hu Bo at first and then flows back, waves are generated, the voltage of the battery cell is increased in different places, the voltage of the battery cell is increased in other places, the electric energy is changed into magnetic energy through conducting magnetization, and then the electric energy is conducted and discharged back to the electric energy, the energy fluctuation in different battery cells is similar to the water wave of lake water waves, the battery cell with the highest voltage can release the energy to the battery cell with the lowest voltage, particularly when the voltages are close to balance, the voltage of the battery cell is quite random like waves, and the time for achieving balance is long and unstable only by the fact that the energy is magnetized in the voltage difference of the battery cell and the magnetic flux in the magnetic core automatically flows back to the natural distribution of the magnetic flux to be magnetized and discharged;

Thirdly, the inductance/transformer is used for converting electric energy into magnetic energy, the energy is connected in parallel in magnetic flux, and then the electric energy is converted back into electric energy, the inductance belongs to a passive element, and is not balanced actively, so that the electric energy is not balanced actively, and unnecessary heat is generated, for example, 16 series-connected electric cores, only one electric core is low in voltage and only the other electric core is high in voltage, then the other 14 electric cores are normal in voltage, the two electric cores are continuously charged and discharged back and forth along with the continuous charging and discharging of the two electric cores, the time is not wasted, unnecessary battery energy loss is generated, the service life loss is afraid, the electric core is good for the charging and discharging of the other electric core, the electric core is not required to be balanced, the electric core is also not required to be charged and discharged with large current, and is not required to be balanced, the electric core 16 series-connected electric cores are used, the method of charging and discharging of TI is used for one MOS conduction in each half cycle, the other 14 electric cores are not in charge and magnetic cores, the half-cycle is not in charge and only 16 MOS conduction, but also in the half-cycle are all the MOS conduction are all in the same, the time is not longer, the time is prolonged, the time is not required to be balanced, the time is prolonged, the dangerous is not in the charge and the time is not balanced, and the electric core is not prolonged, and the time is not consumed, and the dangerous is not balanced, and the electric core is in charge and the 15 charge and is charged and discharged, and is the time and the time is not balanced;

fourth, the electric energy becomes magnetic flux in the magnetic core through the current of the tap winding group, the magnetic flux returns to the process of shunting the current back to the electric core, the magnetic core is better than a lake, the magnetic flux energy in the magnetic core is like wave fluctuation, noise and the like are unavoidable in the circuit and components, so that the fluctuation of the voltage of each electric core cannot be controlled absolutely, the phenomenon possibly causes the problem of balanced oscillation, the electric core with the excessively high original voltage releases energy to the electric core with the low voltage, after the electric core enters the range of the balanced threshold, the electric core cannot enter the range of the balanced threshold, but the inductance loop of the tap group is added, the magnetic flux can not be burnt out, and the parasitic capacitance of the magnetic core and the MOS winding can not be controlled directly, but the magnetic flux can not be burnt out, and the magnetic flux can not be controlled directly. For this purpose, a corresponding technical solution is required to be designed to solve the existing technical problems.

Disclosure of Invention

The invention aims to provide a control system and a control method for actively balancing batteries, which are used for solving the problem that the existing system for actively balancing magnetic energy is limited by the effect of precision of a tap winding transformer on active balancing.

The invention also aims to provide a control system and a control method for actively balancing the battery, which are also used for solving the problems that the time for balancing the battery cells by magnetizing and demagnetizing the battery cells back and forth is long, the battery cells are unstable, the normal battery cells are also charged and discharged continuously along with the battery cells needing to be actively balanced, unnecessary battery energy loss is generated, the service life is prolonged, and balanced oscillation is generated.

The invention provides a control system for actively balancing batteries, which comprises a transformer, wherein the transformer comprises N winding groups with taps; the system also comprises N electric cores which are connected with the N taps of the N tapped winding groups of the transformer in a one-to-one correspondence manner, and also comprises an analog-to-digital converter, a main control unit and 2N switch circuits; the transformer is connected with the 2N switch circuits in a one-to-one correspondence manner through 2N non-tap ends of the transformer, the 2N switches are divided into N switch groups, each switch group comprises two switch circuits, the N switch groups are connected with the N electric cores in a one-to-one correspondence manner, the transformer comprises a magnetic core and N winding groups with taps wound on the magnetic core, all taps of the N winding groups with taps are N taps of the transformer, the N electric cores are divided into i battery groups, and i is an integer greater than or equal to 2;

The analog-to-digital converter comprises N paths of input ends, the N electric cores are connected with the N paths of input ends of the analog-to-digital converter in a one-to-one correspondence manner, and the main control unit is connected with the analog-to-digital converter so as to collect the voltage of each electric core in the N electric cores through the analog-to-digital converter;

All N taps in the N winding groups with taps are connected with anodes of all N electric cores in a one-to-one correspondence manner;

The 2N switch circuits are divided into N switch groups, each switch group comprises two switch circuits, namely a first switch circuit and a second switch circuit, each of the N winding groups with taps is connected with the cathodes of the N battery cells in a one-to-one correspondence manner through one of the N switch groups, and the N winding groups with taps are connected with the N switch groups in a one-to-one correspondence manner;

Each winding group of the N winding groups with taps comprises two non-tap ends, the transformer comprises 2N non-tap ends, and two switch circuits of each switch group of the N groups of switches are respectively connected with the two non-tap ends of the winding group correspondingly connected with the switch group in a one-to-one correspondence manner;

The main control unit is connected to the 2N switch circuits to control the two switch circuits in each switch group to be alternately conducted; when different switch circuits in the same switch group are conducted, the directions of magnetic fluxes generated in the magnetic core by currents flowing through the winding groups connected with the switch circuits of the switch group are opposite, the magnetic core is in a magnetizing state when the first switch circuit is conducted, and the magnetic core is in a discharging state when the second switch circuit is conducted;

The main control unit is further used for calculating average voltage of each battery pack in the i battery packs, controlling the switch of the 2N switch circuits, controlling the wave width modulation duty ratio of each battery pack with the highest average voltage to be more than 50 percent when the first switch circuit correspondingly connected with each battery cell is conducted for magnetizing and to be (50+a)%, and controlling the wave width modulation duty ratio of each battery pack with the highest average voltage to be less than 50 percent when the second switch circuit correspondingly connected with each battery cell is conducted for discharging and to be (50-a)%, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at the wave width modulation duty ratio which is more than 2a percent than the battery pack with the lowest average voltage;

The main control unit is further configured to control, after calculating an average voltage of each of the i battery packs, by controlling the switches of the 2N switch circuits, to control a bandwidth modulation duty ratio of each of the battery packs with the lowest average voltage when the first switch circuit correspondingly connected to the battery cell is turned on to perform magnetizing to be less than 50% (50-a)%, and to control a bandwidth modulation duty ratio of each of the battery packs with the lowest average voltage when the second switch circuit correspondingly connected to the battery cell is turned on to perform discharging to be greater than 50% (50+a)%, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy with a bandwidth modulation duty ratio 2a% greater than that of the battery pack with the highest average voltage.

Preferably, the a% is proportional to the difference between the highest average voltage and the lowest average voltage.

Preferably, a% = (average voltage highest value-average voltage lowest value)/preset voltage equivalent, the preset voltage equivalent is used for adjusting the bandwidth modulation duty cycle;

when the a% > preset fixed percentage, the a% is the preset fixed percentage, and the preset fixed percentage is within a preset range +/-10%.

Preferably, the master control unit is further configured to control a bandwidth modulation duty ratio of the battery pack with the highest average voltage and the battery packs other than the battery pack with the lowest average voltage when the first switch circuit correspondingly connected to each battery cell is turned on to perform magnetization to be 50%, and control a bandwidth modulation duty ratio of the battery pack with the highest average voltage and the battery packs other than the battery pack with the lowest average voltage when the second switch circuit correspondingly connected to each battery cell is turned on to perform magnetization to be 50%.

Preferably, the main control unit is further configured to control a preset wave width modulation duty ratio of 50% when the first switch circuit corresponding to each of the cells in the battery pack not participating in comparing the average voltage is turned on for magnetizing, and control a preset wave width modulation duty ratio of 50% when the second switch circuit corresponding to each of the cells in the battery pack not participating in comparing the average voltage is turned on for magnetizing.

Preferably, the main control unit is further configured to reduce the adjusting frequency of the bandwidth modulation duty cycle when the difference between the highest average voltage value and the lowest average voltage value becomes larger, so as to increase the current of the system during active equalization and further increase the speed of active equalization;

The main control unit is further configured to increase the adjusting frequency of the bandwidth modulation duty cycle when the difference between the highest average voltage value and the lowest average voltage value becomes smaller, so as to reduce the current of the system during active equalization and further increase the stability of active equalization.

Preferably, the adjustment frequency of the bandwidth modulation duty cycle is in a linear planning relationship with the difference value between the highest value of the average voltage and the lowest value of the average voltage, the difference value between the highest adjustment frequency and the lowest adjustment frequency of the bandwidth modulation duty cycle preset by the system is used as an adjustment target of 100%, the adjustment percentage of the adjustment frequency of the bandwidth modulation duty cycle is that the difference value between the highest value of the average voltage and the lowest value of the average voltage is divided by the voltage equivalent of the adjustment frequency of the bandwidth modulation duty cycle preset by the system, and when the adjustment percentage of the adjustment frequency of the bandwidth modulation duty cycle is <5%, the adjustment frequency of the bandwidth modulation duty cycle is the highest adjustment frequency of the bandwidth modulation duty cycle preset by the system.

Preferably, the highest regulating frequency of the preset wave width modulation duty cycle of the system is 50kHzkHz to 200kHz, and the lowest regulating frequency of the preset wave width modulation duty cycle of the system is 10 to 30kHz.

Preferably, the master control unit is further configured to control a duty cycle of bandwidth modulation when the battery pack with the highest average voltage is magnetized at a first control timing in the control cycle to be (50-a)%, control a duty cycle of bandwidth modulation when the battery pack with the highest average voltage is magnetized at a second control timing to be 2a%, and control a duty cycle of bandwidth modulation when the battery pack with the highest average voltage is magnetized at a third control timing to be (50-a)%, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at a duty cycle of bandwidth modulation greater than that of the battery pack with the lowest average voltage by 2 a%; the first control timing sequence, the second control timing sequence, and the third control timing sequence of the control period are continuous; the master control unit is further configured to calculate an average voltage of each of the i battery packs, and then control, by controlling the 2N switch circuits, a bandwidth modulation duty ratio of a battery pack with a lowest average voltage when the first control timing in the control period is magnetizing to be less than 50% (50-a), a bandwidth modulation duty ratio of a battery pack with a lowest average voltage when the second control timing in the control period is magnetizing to be 2a%, and a bandwidth modulation duty ratio of a battery pack with a lowest average voltage when the third control timing in the control period is magnetizing to be (50-a), so as to control the battery pack with a lowest average voltage to convert magnetic energy into electric energy at a bandwidth modulation duty ratio that is more than the battery pack with a highest average voltage by 2 a%;

The main control unit is also used for controlling the battery pack with the highest average voltage to perform magnetism release in the fourth control time sequence in the control period until the magnetism release current is finished; the main control unit is also used for controlling the battery pack with the lowest average voltage to stop magnetizing and discharging in the fourth control time sequence in the control period; the first control timing, the second control timing, the third control timing, and the fourth control timing of the control period are consecutive.

The invention also provides a control method for carrying out active equalization on the battery, which is applied to any control system for carrying out active equalization on the battery, wherein the system comprises a transformer, and the transformer comprises N winding groups with taps; the system further comprises N electric cores which are connected with N taps of the N tapped winding groups of the transformer in a one-to-one correspondence manner, the system further comprises an analog-to-digital converter, a main control unit and 2N switch circuits, the transformer is connected with the 2N switch circuits in a one-to-one correspondence manner through 2N non-tap ends of the transformer, the 2N switches are divided into N switch groups, each switch group comprises two switch circuits, the N switch groups are connected with the N electric cores in a one-to-one correspondence manner, and the main control unit is connected with the 2N switch circuits; the N cells are divided into i battery packs, where i is an integer greater than or equal to 2, and the method includes:

The main control unit collects the voltage of each of the N electric cores through the analog-to-digital converter;

the main control unit calculates the average voltage of each battery pack in the i battery packs;

The main control unit confirms a battery pack with highest average voltage and a battery pack with lowest average voltage, controls the wave width modulation duty ratio of the battery pack with highest average voltage to be more than 50 percent when the first switch circuit correspondingly connected with each battery cell is conducted for magnetizing and to be (50+a)%, and controls the wave width modulation duty ratio of the battery pack with highest average voltage to be less than 50 percent when the second switch circuit correspondingly connected with each battery cell is conducted for discharging and to be (50-a)%, so as to control the battery pack with highest average voltage to convert electric energy into magnetic energy with the wave width modulation duty ratio which is more than 2a percent than the battery pack with lowest average voltage; and the main control unit controls the switch of the 2N switch circuits, the wave width modulation duty ratio of the battery pack with the lowest average voltage when the first switch circuit correspondingly connected with each battery cell is conducted for magnetizing is less than 50 percent and is (50-a)%, and the wave width modulation duty ratio of the battery pack with the lowest average voltage when the second switch circuit correspondingly connected with each battery cell is conducted for magnetizing is more than 50 percent and is (50+a)%, so that the battery pack with the lowest average voltage is controlled to convert magnetic energy into electric energy at the wave width modulation duty ratio which is 2a percent more than the battery pack with the highest average voltage.

Preferably, the a% size is in direct proportion to the difference between the highest average voltage value and the lowest average voltage value, and after the master control unit confirms the battery pack with the highest average voltage and the battery pack with the lowest average voltage, the method further comprises:

the main control unit calculates the difference value of the highest value and the lowest value of the average voltage;

The main control unit calculates and obtains the a% according to the difference value of the highest value and the lowest value of the average voltage; wherein a% = (average voltage highest value-average voltage lowest value)/preset voltage equivalent, the preset voltage equivalent is used for adjusting the bandwidth modulation duty cycle.

Preferably, the method further comprises:

The main control unit judges whether the a% is larger than a preset fixed percentage, and when the a% is larger than the preset fixed percentage, the a% is determined to be the preset fixed percentage, and the preset range of the preset fixed percentage is +/-10% or less.

Preferably, the method further comprises:

The main control unit controls the wave width modulation duty ratio of the battery pack with the highest average voltage and the battery packs with the exception of the battery pack with the lowest average voltage when the first switch circuit connected correspondingly to each battery cell is conducted for magnetizing to be 50%, and controls the wave width modulation duty ratio of the battery pack with the highest average voltage and the battery pack with the exception of the battery pack with the lowest average voltage when the second switch circuit connected correspondingly to each battery cell is conducted for magnetizing to be 50%.

Preferably, the method further comprises:

the main control unit controls the preset wave width modulation duty ratio of the battery packs which are not connected with the battery cells and are high and low to be 50% when the first switch circuit which is connected with the battery cells and is corresponding to the battery cells is conducted to magnetize, and controls the preset wave width modulation duty ratio of the battery packs which are not connected with the battery cells and are high and low to be 50% when the second switch circuit which is connected with the battery cells and is corresponding to the battery cells is conducted to magnetize.

Preferably, the method further comprises:

When the difference value between the highest average voltage value and the lowest average voltage value becomes larger, the main control unit reduces the adjusting frequency of the wave width modulation duty ratio so as to improve the current of the system during active equalization and further accelerate the speed of active equalization;

When the difference between the highest average voltage value and the lowest average voltage value is smaller, the main control unit increases the adjusting frequency of the wave width modulation duty ratio so as to reduce the current of the system during active equalization and further improve the stability of the active equalization.

Preferably, the method further comprises:

The main control unit performs linear programming by taking the difference value between the highest adjusting frequency and the lowest adjusting frequency of the bandwidth modulation duty ratio preset by the system as an adjusting target of 100%;

The main control unit calculates the adjustment percentage of the adjustment frequency of the wave width modulation duty ratio, wherein the adjustment percentage b% of the adjustment frequency of the wave width modulation duty ratio is the difference between the highest average voltage value and the lowest average voltage value divided by the voltage equivalent of the adjustment frequency of the wave width modulation duty ratio preset by the system.

Preferably, the method further comprises:

The main control unit determines that the difference value between the highest average voltage value and the lowest average voltage value is larger than the voltage equivalent of the regulating frequency of the wave width modulation duty cycle preset by the system, wherein the regulating frequency of the wave width modulation duty cycle is the lowest regulating frequency of the wave width modulation duty cycle preset by the system;

When the main control unit determines that b% is less than or equal to 5%, the adjusting frequency of the wave width modulation duty ratio is the highest adjusting frequency of the wave width modulation duty ratio preset by the system;

And when the main control unit determines that the b% is greater than 5%, calculating the adjusting frequency of the bandwidth modulation duty cycle in a linear interpolation manner to obtain an updated adjusting frequency freq_b% of the bandwidth modulation duty cycle, wherein freq_b% = the highest adjusting frequency-b% (the highest adjusting frequency of the bandwidth modulation duty cycle preset by the system-the lowest adjusting frequency of the bandwidth modulation duty cycle preset by the system) of the bandwidth modulation duty cycle.

Preferably, the method further comprises:

The main control unit controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a first control time sequence in a control period, controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be 2a% when the battery pack with the highest average voltage is magnetized at a second control time sequence, and controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a third control time sequence, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at the wave width modulation duty ratio which is more than that of the battery pack with the lowest average voltage by 2 a%; the first control timing sequence, the second control timing sequence, and the third control timing sequence of the control period are continuous;

After calculating the average voltage of each battery pack of the i battery packs, the master control unit controls the 2N switch circuits to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be less than 50% when the battery pack with the lowest average voltage is magnetized at the first control time sequence in the control period to be (50-a), controls the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be 2a% when the battery pack with the lowest average voltage is magnetized at the second control time sequence in the control period, and controls the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be (50-a%) when the battery pack with the lowest average voltage is magnetized at the third control time sequence in the control period to be more than the battery pack with the highest average voltage by 2a% so as to convert magnetic energy into electric energy;

The main control unit controls the battery pack with the highest average voltage to perform magnetism release in the fourth control time sequence in the control period until the magnetism release current is finished, and controls the battery pack with the lowest average voltage to stop magnetism charge and magnetism release in the fourth control time sequence in the control period; the first control timing, the second control timing, the third control timing, and the fourth control timing of the control period are consecutive.

The invention provides a control system and a method for actively balancing batteries, wherein the system comprises a main control unit, the main control unit calculates the average voltage of each battery pack in i battery packs, controls the wave width modulation duty ratio of each battery cell in the battery pack with the highest average voltage to be more than 50 percent when a first switch circuit correspondingly connected with each battery cell is conducted for magnetizing, to be (50+a)%, and controls the wave width modulation duty ratio of each battery cell in the battery pack with the highest average voltage to be less than 50 percent when a second switch circuit correspondingly connected with each battery cell is conducted for magnetizing, to be (50-a)%, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy with the wave width modulation duty ratio which is 2a percent more than that of the battery pack with the lowest average voltage; the battery pack is further used for controlling the wave width modulation duty ratio of each battery cell in the battery pack with the lowest average voltage to be less than 50 percent (50-a)%, when the first switch circuit correspondingly connected with each battery cell is conducted for magnetizing, and controlling the wave width modulation duty ratio of each battery cell in the battery pack with the lowest average voltage to be greater than 50 percent (50+a)%, when the second switch circuit correspondingly connected with each battery cell is conducted for magnetizing, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy at a wave width modulation duty ratio which is 2a percent more than that of the battery pack with the highest average voltage. The method comprises the steps of firstly judging and identifying the battery cells with high voltage and the battery cells with low voltage, then actively controlling to convey the energy of the battery cells with high voltage to the battery cells with low voltage, so that the speed of active equalization is faster than that of natural semi-active equalization, and the total energy consumption generated by a system and the heat generated by the system are reduced along with the reduction of the time of active equalization, thereby prolonging the service life of the system.

According to the invention, the voltages of a plurality of battery cells are grouped, the average voltage of the battery pack after each battery cell is grouped is obtained, the electric energy of the battery cells with different average voltages is controlled to be converted into magnetic energy in a magnetic core through magnetizing of a multi-winding transformer by a first switch circuit (which can be a MOS switch) according to the average voltage of the battery cells, all the magnetic energy is mixed and added in the magnetic core of the transformer, then the magnetic energy is converted into currents with different magnitudes according to the average voltage distribution of the battery cells, and the currents are returned to the battery cells with different average voltages by controlling a second switch circuit (which can be a MOS switch), so that the energy of the battery cells with high voltages is actively transmitted to the battery cells with low voltages, and the aim of real active equalization is achieved. Specifically, in the process of magnetizing and demagnetizing the magnetic core through the tap winding group by using the high-frequency MOS switch, the electric core group with higher average voltage is magnetized to one point of the magnetic core, and the electric core group with lower average voltage is magnetized to one point when the magnetic energy of the magnetic core is magnetized, so that the electric energy of the electric core group with higher average voltage can be quickly transmitted to the electric core group with lower average voltage through the magnetic core.

Still further, the main control unit is further configured to reduce the frequency of adjusting the duty cycle of the bandwidth modulation when the difference between the highest value of the average voltage and the lowest value of the average voltage becomes larger, so as to increase the current of the system during active equalization and further increase the speed of active equalization; the main control unit is further configured to increase the adjusting frequency of the bandwidth modulation duty cycle when the difference between the highest average voltage value and the lowest average voltage value becomes smaller, so as to reduce the current of the system during active equalization and further increase the stability of active equalization. According to the embodiment, when the average voltage difference between the two groups of the battery cells with the highest average voltage and the lowest average voltage is larger, the difference of the magnetizing and discharging currents of the two groups of the battery cells is increased, so that the balancing speed is high, and when the average voltage difference between the two groups of the battery cells with the highest average voltage and the lowest average voltage is smaller, the difference of the magnetizing and discharging currents of the two groups of the battery cells is reduced, so that the balancing stability is improved, and balanced oscillation cannot be generated.

Still further, the main control unit is further configured to increase the adjusting frequency of the bandwidth modulation duty cycle when the difference between the highest average voltage value and the lowest average voltage value is smaller, so as to reduce the current of the system during active equalization, and further improve the stability of active equalization. The embodiment provides an algorithm and a control method for adaptively controlling all balanced current of the whole system by adjusting the adjusting frequency of the bandwidth modulation duty ratio from the electric core grouping transferring electric energy with high average voltage to the electric core grouping with low average voltage according to the maximum value of the voltage value difference of the average voltage of each electric core grouping, so that the balanced current of the whole system is larger when the voltage value difference of the average voltage of each electric core grouping is larger, the balanced speed is higher, and the balanced current of the whole system is smaller when the voltage value difference of the average voltage of each electric core grouping is smaller, thereby improving the balanced stability and avoiding balanced oscillation.

Drawings

For a clearer description of the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly introduced below, it being obvious that the drawings in the description below are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art, wherein:

FIG. 1a is a block diagram of a control system for actively balancing batteries according to an embodiment of the present invention;

FIG. 1b is a block diagram of another control system for actively balancing batteries according to an embodiment of the present invention;

FIG. 2 is a block diagram of another control system for actively balancing batteries according to an embodiment of the present invention;

fig. 3a is a schematic diagram of a duty cycle of bandwidth modulation according to an embodiment of the present invention;

FIG. 3b is a schematic diagram of another principle of the duty cycle of the bandwidth modulation according to the embodiment of the present invention;

FIG. 3c is a schematic diagram of another principle of the duty cycle of the bandwidth modulation according to the embodiment of the present invention;

FIG. 3d is a schematic diagram of another principle of the duty cycle of the bandwidth modulation according to the embodiment of the present invention;

fig. 4 is a flowchart of a control method for actively balancing a battery according to an embodiment of the present invention;

fig. 5 is a flowchart of another control method for actively balancing a battery according to an embodiment of the present invention;

fig. 6 is a flowchart of another control method for actively balancing a battery according to an embodiment of the present invention;

fig. 7 is a schematic diagram of a frequency adjustment of a duty cycle of wave width modulation according to an embodiment of the present invention.

Detailed Description

The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The invention aims to provide a control system and a control method for actively balancing batteries, which are used for solving the problems that the existing system for actively balancing magnetic energy is limited by the effect of precision of a transformer realized by a tap winding group on active balancing, the time for balancing by magnetizing and demagnetizing cells back and forth is long, the cells are unstable, the normal cells are also required to be continuously charged and discharged back and forth along with the cells needing active balancing, unnecessary battery energy loss is generated, the service life is prolonged, and the balance oscillation is realized.

Referring to fig. 1 a-7, as shown in fig. 1a, a control system module diagram for actively balancing a battery is provided, wherein the system includes a transformer 110, N electric cores 120, an analog-to-digital converter 130, a main control unit 140, and 2N switch circuits 150; the transformer 110 includes a magnetic core 111 and N tapped winding groups 112 wound around the magnetic core 111, and the N electric cores 120 are divided into i battery groups, i being an integer greater than or equal to 2, i.e., at least two battery groups, such as the battery group 121 and the battery group 122 shown in fig. 1 a. In other embodiments, each tapped winding 112 of the N tapped windings 112 may be replaced with two non-tapped windings. In the embodiment of the present invention, as shown in fig. 1a, a master control unit 140 is included, and in other embodiments, the master control unit 140 may be replaced by a plurality of master control units 140 or master control chips, so as to implement the system function and method for active equalization provided in the embodiment of the present invention. The N electric cores 120 are connected with the N taps of the transformer 110 in a one-to-one correspondence. The transformer 110 is connected to the 2N switch circuits 150 in a one-to-one correspondence manner through 2N non-tap ends of the transformer 110, the 2N switches are divided into N switch groups, each switch group includes two switch circuits, and the N switch groups are connected to the N electric cores 120 in a one-to-one correspondence manner.

In the system provided by the embodiment of the invention, the analog-to-digital converter 130 includes N input ends, the N electric cores 120 are connected with the N input ends of the analog-to-digital converter 130 in a one-to-one correspondence manner, and the main control unit 140 is connected with the analog-to-digital converter 130 to collect the voltage of each electric core 120 in the N electric cores 120 through the analog-to-digital converter 130.

In the system provided by the embodiment of the invention, all N taps in the N winding groups 112 with taps are connected with anodes of all N electric cores 120 in a one-to-one correspondence manner.

In the system provided by the embodiment of the invention, 2N switch circuits 150 are divided into N switch groups, for example, switch group 1 and other switch groups N, each switch group includes two switch circuits, namely, a first switch circuit 151 and a second switch circuit 152, each of N tapped winding groups 112 is connected to the negative poles of N electric cores 120 in a one-to-one correspondence manner through one of the N switch groups, and N tapped winding groups 112 are connected to the N switch groups in a one-to-one correspondence manner. As shown in fig. 1a, in the embodiment of the present invention, the 2N switch circuits 150 are respectively implemented by 2N MOS switches. That is, each of the N cells 120 is connected to two MOS switches of the 2N MOS switches, respectively, the 2N MOS switches are divided into N switch groups, the N cells 120 are connected to the N switch groups in one-to-one correspondence, and two MOS switches of each of the N switch groups are connected to the cell 120 to which the switch group belongs.

In the system provided by the embodiment of the invention, each winding group 112 of the N winding groups 112 with taps comprises two non-tap ends, and two switch circuits of each switch group of the N switch groups are respectively connected with two non-tap ends of the winding group 112 correspondingly connected with the switch of the group in a one-to-one correspondence manner. In the embodiment of the present invention, as shown in fig. 1a, 2N MOS switches are connected to all non-tapped terminals in N tapped winding groups 112.

In the system provided by the embodiment of the invention, the main control unit 140 is connected to 2N switch circuits 150 to control the two switch circuits in each switch group to be alternately turned on; when the different switch circuits 150 in the same switch group are turned on, the direction of magnetic flux generated in the magnetic core 111 by the current flowing through the winding group 112 connected with the switch circuits of the switch group is opposite, the magnetic core 111 is in a magnetizing state when the first switch circuit 151 is turned on, in a high-frequency switch state, the first switch circuit is turned on, the current gradually increases to magnetize the magnetic core, then the first switch circuit is turned off, and when the second switch circuit 152 is turned on, the magnetic core 111 is in a demagnetizing state, the current is transferred from the first switch circuit to the second switch circuit, the current is unchanged at the moment, then the current gradually decreases, and the magnetic energy is transferred from the magnetic core 111 to the electric core 120. As shown in fig. 1a, in the embodiment of the present invention, the main control unit 140 is connected to 2N MOS switches. Each cell 120 is connected to a tapped winding 112 via 2 MOS switches connected to it. The taps of the tapped winding 112 are connected to the positive poles of the cells 120 to which they are connected. The two non-tapped ends of the tapped winding group 112 are respectively connected with one MOS switch of the two MOS switches correspondingly connected with the winding group 112, and are connected back to the negative electrode of the battery cell 120 connected with the tapped winding group 112, namely, the positive electrode of the battery cell 120 is connected back to the negative electrode of the battery cell 120 through the winding group 112 and the two MOS switches. In the embodiment of the present invention, 2 MOS switches connected to the positive electrode of the battery cell 120 are alternately turned on, and when a first MOS switch (i.e., the first switch circuit 151) of the 2 MOS switches connected to the positive electrode of the battery cell 120 is turned on, the magnetic core 111 is magnetized to create magnetic flux, and when the magnetic core 111 is in a magnetized state, the positive electrode of the battery cell 120 connected to the first 2 MOS switch (i.e., the first switch circuit 151) gradually increases the current flowing out to the winding group 112 connected to the battery cell 120. Then, a first MOS switch of the 2 MOS switches connected to the positive electrode of the battery cell 120 is in an off state, and a second MOS switch (i.e., the above-mentioned second switching circuit 152) of the 2 MOS switches connected to the positive electrode of the battery cell 120 is controlled to be turned on, so that the magnetic energy in the magnetic core 111 is demagnetized to the battery cell 120 connected to the 2 MOS switches, the magnetic core 111 is in a demagnetized state, and when the magnetic core 111 is in a demagnetized state, the current in the winding group 112 connected to the battery cell 120 gradually decreases.

In the system provided by the embodiment of the present invention, the main control unit 140 is connected to the 2N switch circuits 150, and the main control unit 140 is further configured to calculate an average voltage of each of the i battery packs, control, by controlling the switches of the 2N switch circuits 150, a wave width modulation duty ratio when the first switch circuit 151 correspondingly connected to each of the battery cells 120 in the battery pack with the highest average voltage is turned on to perform magnetization to be greater than 50%, and to be (50+a)%, and control, by controlling the switches of the 2N switch circuits 150, a wave width modulation duty ratio when the second switch circuit 152 correspondingly connected to each of the battery cells 120 in the battery pack with the highest average voltage is turned on to perform magnetization to be less than 50%, and to be (50-a)%, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at a wave width modulation duty ratio 2a% greater than the battery pack with the lowest average voltage. In the embodiment of the present invention, as shown in fig. 1a, it is assumed that the battery pack 121 is the battery pack having the highest average voltage among all the battery packs, and the battery pack 122 is the battery pack having the lowest average voltage among all the battery packs.

In the system provided by the embodiment of the present invention, the main control unit 140 is further configured to calculate an average voltage of each of the i battery packs, control a bandwidth modulation duty ratio of each of the battery packs 120 with the lowest average voltage when the first switch circuit 151 correspondingly connected to each battery pack is turned on to perform magnetization to be less than 50% (50-a)%, and control a bandwidth modulation duty ratio of each of the battery packs with the lowest average voltage when the second switch circuit 152 correspondingly connected to each battery pack 120 is turned on to perform magnetization to be greater than 50% (50+a)%, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy with a bandwidth modulation duty ratio 2a% greater than that of the battery pack with the highest average voltage.

In the system provided by the embodiment of the present invention, after the master control unit 140 calculates the average voltage of each of the i battery packs, it controls all the first MOS switches (i.e. the first switch circuit 151) that magnetize the core 111 in the high-frequency charging and discharging to have a longer duty cycle, and the first MOS switches (i.e. the first switch circuit 151) that magnetize the core 111 in the high-frequency charging and discharging to have a shorter duty cycle, and it controls all the first MOS switches (i.e. the first switch circuit 151) that magnetize the core 111 in the high-frequency charging and discharging to have a shorter duty cycle, and the core 111 is magnetized to have a longer duty cycle, so that the energy of the core 120 is converted into the magnetic energy in the core 111 through the winding 112, and then the magnetic energy is converted back to the core 120 through the winding 112.

Preferably, the magnitude of a% is proportional to the difference between the highest value of the average voltage and the lowest value of the average voltage.

Preferably, a% = (average voltage highest value-average voltage lowest value)/preset voltage equivalent, the preset voltage equivalent is used for adjusting the bandwidth modulation duty cycle; when a% > the preset fixed percentage, a% is the preset fixed percentage, and the preset fixed percentage is within a preset range of +/-10%.

Preferably, the main control unit 140 is further configured to control the bandwidth modulation duty ratio of the first switch circuit 151 correspondingly connected to each of the battery cells 120 in the battery pack except for the battery pack with the highest average voltage and the battery pack with the lowest average voltage to be 50% when conducting and magnetizing, and control the bandwidth modulation duty ratio of the second switch circuit 152 correspondingly connected to each of the battery cells 120 in the battery pack except for the battery pack with the highest average voltage and the battery pack with the lowest average voltage to be 50% when conducting and magnetizing. In the system provided by the embodiment of the invention, the battery pack with the highest average voltage and the battery packs with the lowest average voltage except the battery pack with the highest average voltage respectively occupy half of the time of magnetization and the time of magnetization so as to achieve the effect of automatic magnetic reset, the battery packs with the highest average voltage are lengthened and the battery packs with the lowest average voltage are shortened and magnetized as well, the added magnetization amount and the reduced magnetization amount counteract each other, the total magnetic flux caused by magnetization is equivalent to that all the battery cells 120 are magnetized in half of the period, and in the same way, the magnetization amounts corresponding to the difference of the magnetization duty ratios of the battery packs with the highest average voltage and the battery packs with the lowest average voltage in magnetization are also counteracted each other, and the total magnetic flux released in magnetization is equal to that all the battery cells 120 are magnetized in half of the period so as to achieve the effect of natural magnetic reset.

In the control system for actively balancing the battery according to the embodiment of the present invention, compared with the semi-active balancing technique, the control signals of the main control unit 140 are not a set of complementary control signals. In the semi-active equalization technology, one of the complementary control signals controls all the magnetizing switches, the other control signal controls all the discharging switches, so that only the energy of all the battery cores 120 can be mixed inside the magnetic core 111 naturally, and then the battery cores 120 can be returned naturally, and the repeated magnetizing and discharging are performed, so that the active equalization technology is a natural balance which cannot be actively controlled. In the control system for actively balancing the battery provided by the embodiment of the invention, the energy of the high-voltage battery 120 can be controlled to the energy of the low-voltage battery 120 by confirming the high-voltage battery 120 and the low-voltage battery 120, so that a real active balancing effect is realized.

As shown in fig. 1b, in the control system for actively balancing a battery according to the embodiment of the present invention, the main control unit 140 includes an analog-to-digital converter 130, for example, the main control unit 140 and the analog-to-digital converter 130 may be implemented by a 32-bit main control chip, for example, a 32-bit main control chip, where the analog-to-digital converter 130 includes 16 inputs. Specifically, the system can be a 32-bit ARM Cortex-M0+ kernel, a built-in CORDIC coprocessor and a 16-channel A/D converter, supports 26 PWM channels, and is provided with an LDO and LCD/LED display driving chip.

In the control system for actively equalizing the batteries provided in the embodiment of the present invention, N battery cells 120 are divided into i battery packs, when the main control unit 140 controls the i battery packs, each battery pack only needs two control lines, the first control line controls all the first MOS switches (i.e. the first switch circuit 151) that are turned on to magnetize the corresponding battery pack, and the second control line controls all the second MOS switches (i.e. the second switch circuit 152) that are turned on to magnetize the corresponding battery pack, because the timing of the control signals of the first MOS switches/the second MOS switches in the same battery pack is the same, that is, the ac components of the signals are the same, but the dc potentials of the serial battery cells 120 are different, and it is a well known process in the art to superimpose the ac control signals on the negative electrode potentials of different battery cells 120 and the gates of some simple bias circuits to control the different dc potentials.

As shown in fig. 2, another block diagram of a control system for actively balancing the battery is provided, and in contrast to the control system for actively balancing the battery shown in fig. 1b, the signal connection relationship between the main control unit 140 and the 2N switch circuits 150 is mainly shown in fig. 2. In the control system for actively balancing the batteries shown in fig. 2, as in fig. 1b, the N cells 120 are divided into i battery packs, i is an integer greater than or equal to 2, i.e., at least two battery packs, and the 2N switch circuits 150 are divided into N switch packs, each including two switch circuits. Unlike fig. 1b, the N groups of switches in fig. 2 are divided into i cluster switch groups according to the relationship between each switch group and the battery group to which the battery cell 120 corresponding to the switch group belongs. The number i of the cluster switch groups is the same as the number i of the battery groups, as shown in fig. 2, and the cluster switch groups 1, i-n and n are a plurality of integers greater than or equal to 1 and less than i are shown. When the master control unit 140 realizes the master control balancing function, the i cluster switch groups are respectively controlled by the i cluster switch group control signals, and the cluster switch group control signal for controlling any cluster switch group is used for realizing the active balancing control of the battery groups correspondingly connected with the cluster switch groups. Therefore, the control system for active balancing of the battery provided by the embodiment of the invention can achieve the purpose of 'active' in a true sense only if the control system for active balancing of the battery provided by the embodiment of the invention is different from the current semi-active balancing technology in that the control system for active balancing of the battery is used for realizing the full active battery balancing control technology by controlling the i cluster switch group control signals of the i cluster switch groups.

In the control system for actively balancing the battery shown in fig. 2, the analog-to-digital converter 130 is implemented as the 32-bit master control chip described above, and the analog-to-digital converter 130 is integrated in the master control unit 140.

Preferably, in the system provided by the embodiment of the present invention, the main control unit 140 is further configured to control a preset bandwidth modulation duty ratio of 50% when the first switch circuit 151 connected to each of the battery cells 120 in the battery pack not participating in comparing the average voltage is turned on to magnetize, and control a preset bandwidth modulation duty ratio of 50% when the second switch circuit 152 connected to each of the battery cells 120 in the battery pack not participating in comparing the average voltage is turned on to magnetize.

Currently, one of the most application areas where active equalization techniques are needed is in shared electric bicycles employing battery charging cabinets. Because when the electric bicycle is charged, if the battery voltage is not balanced, the electric core 120 with higher internal resistance is charged in advance to cut off the charging, so that the battery electric quantity is insufficient, and when the electric bicycle is discharged, the output voltage is lower due to higher internal resistance, so that the system is discharged in advance to cut off the discharging, the endurance of the electric bicycle is insufficient, and the probability of anchoring in a half way is improved.

In the shared electric bicycle system, the lack of endurance can lead to the consequence that the user cannot ride the shared electric bicycle back to the charging cabinet to return to the charging battery, and the user can only discard the bicycle in half way without forced. However, with the charging cabinet system with active equalization, no matter whether the battery cells 120 are good or bad, at least the battery is fully charged in the charging cabinet, and after active equalization control, the battery cells 120 with lower original electric quantity can be ridden for the time, and after active equalization control, the voltage electric quantity is similar to other battery cells 120, so that the endurance of the time can be prolonged.

When the shared electric bicycle is used, if some of the electric cores 120 are seriously aged after the riding is finished, the electric cores 120 with higher internal resistances are abnormal in voltage, and the battery must be subjected to active equalization technical treatment again in the charging process before the next riding, so that the endurance of the next riding can be ensured. That is, active equalization can improve endurance, but there is no way to reduce too high internal resistance, but if there are some cells 120 with serious aging, in active equalization, because there is a step of measuring the voltage of each cell 120, according to the voltage history of the cell 120, the bad cells 120 can be identified, and for cells 120 with too serious aging, the charging cabinet is locked to be taken out by a general user, and the background is notified to perform maintenance treatment, and the bad cells 120 are replaced. Preferably, in the system provided by the embodiment of the present invention, the main control unit 140 is further configured to record a voltage change condition of each of the battery cells 120, identify the problem battery cell 120 according to the voltage change condition of all the battery cells 120, lock the battery pack where the problem battery cell 120 is located, send a notification to be maintained of the battery cell 120, and report the background to repair the problem battery cell 120.

Taking an electric bicycle as an example, the grouping situation of the battery cells 120 in the control system for actively balancing the battery provided by the embodiment of the invention is described. The voltages frequently used by the electric bicycle are 24V, 48V, 60V and 72V, for example, iron lithium batteries are used as examples, namely 8 sections, 16 sections, 20 sections and 24 sections of electric cores 120 are connected in series, the electric cores 120 are distributed into i groups, because N is an even number, and the whole group distribution is just carried out, for example, i=2, the electric core 120 with high voltage can be enabled to be subjected to the judgment of the average voltage of the groups, and the energy of the groups with higher average voltage is actively transferred to the group with lower average voltage through the difference of different magnetizing and discharging duty ratios, so that the balancing process is accelerated.

Since many Analog-to-digital conversion devices have only 8, even only 4, for convenience, and 4 or 8 Analog-to-Digital Converter ADC circuits are used as a group, for example, n=16, and when the Analog-to-ADC 130 (Analog-to-Digital Converter ADC) is 4 inputs, there is an average voltage of 4 groups, and for controlling the single purification of the circuit and avoiding the need for active magnetic reset, only the group with the highest average voltage and the group with the lowest average voltage perform "active equalization", and the average voltages of the other two groups are neither the highest nor the lowest or as above, the magnetizing and the discharging time is half, and naturally participates in the equalization process.

Taking the example of the 32-bit main control chip as an example, a single chip microcomputer is integrated with a 12-bit ADC with 16-way input, and for the application of 8 strings, 12 strings or 16 strings of battery cores 120, the number of the battery cores 120 with the same number of 2 groups can be directly divided for active equalization; for 24 strings of cells 120, the cells can be processed in 3 groups of 8 strings, and for 32 strings of cells 120, the cells can be processed in 2 groups of 16 strings.

Preferably, in the system provided by the embodiment of the present invention, the main control unit 140 is further configured to calculate and confirm that the maximum voltage difference between all the battery cells 120 falls to a preset threshold range for ending the equalization control, and then control the external power supply to charge all the battery cells 120/the battery pack, and start the active equalization control function of the next round after the charging is ended, and start the active equalization control operation for the control system for performing active equalization on the battery.

The judgment of starting and ending the active equalization is performed by using the voltage difference between the highest voltage of the single cell 120 and the lowest voltage of the single cell 120, but it is possible that the cell 120 with the highest voltage of the single cell 120 appears in the group with the highest average voltage, which does not affect the performance of the active equalization, because the cell 120 with the highest voltage of the single cell 120 is not in the group with the highest average voltage, and thus the on time is shorter, but in the same battery pack, the cell 120 with the highest voltage still generates the largest current on the tap winding set 112 to magnetize the cell 120, after the group with the highest average voltage is subjected to the duty cycle modulation to release more energy to the group with the lowest average voltage, the average voltage ranking of the group with the highest average voltage of the single cell 120 is reduced, and the ranking of the group with the highest average voltage of the single cell 120 is naturally improved, and further under the worst condition, the cell 120 with the highest average voltage of the single cell 120 appears in the group with the lowest average voltage, and the cell 120 with the highest average voltage can still generate the largest current on the tap winding set 112 because the cell with the highest voltage is still charged on the tap winding set 112.

The average voltage of the group reflects that the voltage of the whole group represents the group with the highest energy of the plurality of battery cells 120 in the group, so that the method for adjusting the duty ratio can reach the active balancing effect at the highest speed and ends the active balancing threshold range without taking the voltage of the single battery cell 120 as the parameter for adjusting the duty ratio during the active balancing transportation. It is noted, however, that the maximum voltage difference between all the individual cell 120 voltages is compared to a preset threshold range for ending the equalization control, rather than the voltage difference between the average voltages of the groups.

As described above, the current of the electric energy passing through the tap winding 112 becomes magnetic flux in the magnetic core 111, the magnetic flux returns to the current form and shunts back to the battery core 120, the magnetic core 111 is better than a lake, the magnetic flux energy in the magnetic core is like wave fluctuation, the circuit and components are inevitably free from noise, noise and the like, various stray and parasitic capacitances and inductances are added, so that the voltage fluctuation of each battery core 120 cannot be controlled absolutely, the phenomenon may cause a problem of balanced oscillation, the parasitic capacitance inductance of the MOS switch and the circuit wiring are bad, the problem is especially troublesome, the battery core 120 with the original voltage is released to the battery core 120 with the low voltage, the battery core 120 is already in the end balanced threshold range, but at this time, the maximum voltage difference of the voltage between the single battery core 120 is found to be larger than the end balanced threshold because of noise or the oscillation caused by the ADC resolution is not linear or parasitic capacitance inductance, and the energy is often removed from the end balanced threshold range again in the next sampling period if the voltage is immediately reversed, the energy is carried in the opposite direction again.

Therefore, in the system provided by the embodiment of the present invention, the main control unit 140 is further configured to start the active equalization control function after calculating and confirming that the maximum voltage difference of all the battery cells 120 is greater than the preset threshold value for starting the equalization control, and start the active equalization control operation for the control system that performs active equalization on the battery.

For example, if the threshold for ending the equalization control is set to be 2mV, the threshold for starting the equalization control may be set to be 10mV, then the maximum voltage difference between the voltages of the single cells 120 after entering the equalization state is less than 2mV, and the maximum voltage difference between the voltages of the single cells 120 is gradually reduced after ending the equalization operation, for example, the equalization control is self-discharged, or the equalization control is taken out and put back into the charging cabinet, and the active equalization control process is re-entered only after the maximum voltage difference between the voltages of the single cells 120 is again greater than 10mV, so that the above-mentioned problem of equalization oscillation may be avoided, however, when the equalization control threshold is set to be 10mV for recycling the electric bicycle from the cell 120 of the retired electric bicycle for a step, the equalization control threshold may be set to be 20mV, and even if some systems which have to sacrifice the hardware cost are selected, the equalization control threshold must be set to be 50mV or higher, so that unnecessary equalization oscillation phenomenon may be avoided.

Many electric bicycle batteries have started to use the lithium iron batteries which are recovered in a gradient after the electric automobile is retired, the internal resistance of the batteries has increased so much that the discharge voltage is lower and uneven, so if a power supply system of 36V is made by using 12 strings of electric cells 120 according to the common practice in the industry, the voltage of the commercial male model control board cannot effectively push a standard motor used by the male model system, horsepower is insufficient and endurance is insufficient, and at the moment, the serial number can be increased to 13 strings to compensate and treat the problem. There are also cases where the battery cells 120 are not problematic, and the purpose is that the manufacturer who has the idea of having stronger horsepower and longer endurance than other manufacturers will also adopt the design of 13 strings of battery cells 120. Similarly, there are also 16 series-connected cells 120 to 17 series-connected cells, and 24 series-connected cells 120 to 25 series-connected cells, and for these special series-connected numbers, which are not even numbers, it is not enough to simply divide the series-connected cells into two groups, but when 13 cells 120 or 17 cells 120 are connected in series, 13 and 17 are prime numbers, even if they are divided into 2 groups/3 groups/4 groups/5 groups/6 groups/7 groups/8 groups, the number of cells 120 in each group cannot be the same, i.e. the number of cells 120 of each cell group of the obtained i cell groups may be different from each other.

The following describes a method for solving the situation that N number of cells 120 cannot be divided into i number of battery packs equal to the number of cells 120 except for 1 in the battery pack when N number of cells 120 is prime number, or the maximum common factor of N is small, so that q is large when divided into q groups equal to the number of cells 120, for example q is equal to or greater than 6, when this situation tries to divide N into i number groups, where i is equal to or greater than 5, i.e. let i=3, 4 or 5, when grouping, where the number of cells 120 in i-1 group is the same, assuming 1 st to i-1 th groups, the number of cells 120 in the remaining group is different from other i-1 groups, assuming that it is i number, the grouping of cells 120 in fig. 1a and 2 is i number group, when the master control unit 140 calculates the average voltage of each battery pack, the i number of cells 120 is different, the comparison of the highest average voltage and the lowest average voltage is not participated, the main control unit 140 directly controls the ith group to control the magnetizing and the discharging to occupy half of the time during the active balancing, and the other 1 st to i-1 st groups are participated in the active balancing, the average voltage of each group is compared, the period of the switch corresponding to the battery group with the highest average voltage for magnetizing the magnetic core 111 during the high-frequency charging and discharging is controlled to be longer, the period of the switch corresponding to the battery group with the lowest average voltage for discharging the magnetic core 111 during the high-frequency charging and discharging is controlled to be shorter, the period of the switch corresponding to the battery group with the lowest average voltage for discharging the magnetic core 111 for discharging the magnetic core 120 is controlled to be longer, the energy of the battery core 120 is converted into the magnetic energy in the magnetic core 111 through the tap winding group 112, and the magnetic energy is converted back into the battery core 120 through the tap winding group 112, the battery pack with the highest average voltage outputs more magnetic energy, the more magnetic energy is transmitted to the battery pack with the lowest average voltage, the active equalization effect is achieved, other battery packs with the highest average voltage or the lowest average voltage and the battery pack with the ith battery pack are not in the highest average voltage or the lowest average voltage, and magnetizing and discharging time is the same and takes half of time.

Taking n=13 above as an example, if i=3 is set, the 1 st group is the 5 th series of cells 120, the 2 nd group is the 5 th series of cells 120, the 3 rd group is the 3 rd series of cells 120, the 1 st and 2 nd groups are compared with average voltages to perform active equalization, the 3 rd group does not participate in comparison, and participates in active equalization in the natural semi-active equalization mode, and if i=5 is set, the 1 st to 4 th groups are the 3 th series of cells 120, the 5 th group is the 1 st series of cells 120, the two groups with the highest average voltages and the lowest average voltages among the 1 st to 4 th groups use duty ratio difference to perform active equalization, and the other groups take half of time for magnetizing and discharging respectively, and participate in active equalization in the natural semi-active equalization mode.

Regarding the switching frequency of the switching circuit 150, typically the MOS switch will be chosen to be higher than 20kHz, so that such high frequency noise is not audible to the human ear. However, as in the previous principle, inductance= jwL, where w=2pi f, decreasing the frequency is to decrease the inductance, so that the current of the tap winding 112 can be increased, so that the switching frequency of the switching circuit 150 can be as low as 10kHz, and thus a larger current acceleration equalization can be obtained. However, in consideration of cost, the higher the frequency of the high frequency, the smaller the inductance and capacitance, the lower the cost, and the easiness of high frequency filtering, the general design scheme can take the range of 100kHz to 200kHz without needing large current, and the implementation is easy and the cost is lower.

In the active equalization control system provided in the embodiment of the present invention, ADC analog-to-digital conversion is not required in each switch, only a period of time is required to read the voltage value of each cell 120 once, because the time from the maximum cell 120 voltage difference exceeding the initial equalization control threshold value to the time when the cell 120 voltage equalization is performed to enter the final equalization control threshold value is over 1 minute, even several hours, the time interval from one ADC reading to the next ADC reading is 0.1 seconds to 5 seconds is sufficient, because the difference in duty ratio causes energy to flow from the cell group with the highest average voltage to the cell group with the lowest average voltage, the dc component of the high-frequency current is the equalization current, when the equalization current is large, the interval time is short, so as to avoid that the current sampling is higher than the group, and because the interval time is too long, when the next sampling is performed, the time is reversed, and the cell 120 voltage difference exceeds the set initial equalization threshold value again, the time interval between the ADC sampling is caused to be larger, and the time interval between ADC sampling is shorter.

In order to avoid the need of short interval time of ADC reading, the ADC can be carried out once after a plurality of active equalization periods, and the difference of the duty cycle of wave width modulation is utilized in the front, so that more magnetic energy is output by the battery cell 120 group with the highest average voltage, and the more magnetic energy is transmitted to the battery cell 120 group with the lowest average voltage, thereby achieving the effect of active equalization, and the preferable difference of the duty cycle is between 1% and 10% so as to avoid the balanced oscillation.

The voltage of a lithium battery is a function of temperature, with higher temperatures being higher voltages. Therefore, the voltage of the battery cell 120 entering the active equalization is different from the other battery cells 120 due to the fact that the temperature is different, the voltage of the battery cell 120 also changes along with the temperature, in order to eliminate the voltage drift caused by the temperature, the MOS switch can be controlled to fully release the magnetic energy in the magnetic core 111 back to the battery cell 120 in the battery pack, then all the MOS switches are closed for a period of time, the temperature of the battery cell 120 is slightly reduced, and the temperature of the single battery cell 120 is relatively close to the average temperature of all the battery cells 120, then the ADC conversion is performed after the temperature is relatively close to the average temperature of all the battery cells 120.

Preferably, in the control system for actively balancing a battery provided by the embodiment of the present invention, the main control unit 140 is further configured to reduce the frequency of adjusting the duty cycle of wave width modulation when the difference between the highest value and the lowest value of the average voltage becomes larger, so as to increase the current of the system during active balancing and further increase the speed of active balancing. The main control unit 140 is further configured to increase the adjusting frequency of the bandwidth modulation duty ratio when the difference between the highest average voltage value and the lowest average voltage value becomes smaller, so as to reduce the current of the system during active equalization and further increase the stability of active equalization.

Preferably, the difference between the maximum adjustment frequency and the minimum adjustment frequency of the bandwidth modulation duty cycle is used as a 100% adjustment target to perform linear programming, the adjustment percentage of the adjustment frequency of the bandwidth modulation duty cycle is the voltage equivalent of the adjustment frequency of the bandwidth modulation duty cycle preset by the system divided by the difference between the maximum average voltage and the minimum average voltage, and when the adjustment percentage of the adjustment frequency of the bandwidth modulation duty cycle is less than 5%, the adjustment frequency of the bandwidth modulation duty cycle is the maximum adjustment frequency of the bandwidth modulation duty cycle preset by the system.

Preferably, the highest regulating frequency of the preset wave width modulation duty cycle of the system is 50kHz to 200kHz, and the lowest regulating frequency of the preset wave width modulation duty cycle of the system is 10kHz to 30kHz.

Preferably, the master control unit 140 is further configured to control a duty cycle of bandwidth modulation when the battery pack with the highest average voltage is magnetized at a first control timing in the control cycle to be (50-a)%, control a duty cycle of bandwidth modulation when the battery pack with the highest average voltage is magnetized at a second control timing to be 2a%, and control a duty cycle of bandwidth modulation when the battery pack with the highest average voltage is magnetized at a third control timing to be (50-a)%, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at a duty cycle of bandwidth modulation greater than that of the battery pack with the lowest average voltage by 2 a%; the first control timing sequence, the second control timing sequence, and the third control timing sequence of the control period are continuous;

The master control unit 140 is further configured to calculate an average voltage of each of the i battery packs, and then control, by controlling the 2N switch circuits 150, a bandwidth modulation duty ratio of a battery pack with a lowest average voltage when the first control timing in the control period is magnetizing to be less than 50% (50-a)%, a bandwidth modulation duty ratio of a battery pack with a lowest average voltage when the second control timing in the control period is magnetizing to be 2a%, and a bandwidth modulation duty ratio of a battery pack with a lowest average voltage when the third control timing in the control period is magnetizing to be (50-a)%, so as to control the battery pack with a lowest average voltage to convert magnetic energy into electric energy at a bandwidth modulation duty ratio that is greater than the battery pack with a highest average voltage by the 2 a%;

and, the main control unit 140 is further configured to control the battery pack with the highest average voltage to perform the demagnetization in the fourth control timing sequence in the control period until the demagnetization current is ended; the main control unit 140 is further configured to control the battery pack with the lowest average voltage to stop magnetizing and discharging at the fourth control timing in the control period; the first control timing, the second control timing, the third control timing, and the fourth control timing of the control period are consecutive.

As shown in fig. 3a, further explaining the principle of the duty ratio of the wave width modulation in detail, 3 kinds of waveforms in fig. 3a are examples of all three kinds of duty ratios of the wave width modulation, the waveform 310 is the control signal PWM (pulse width modulation) duty ratio 50+a% sent by the main control unit 140, the horizontal stripe block 312 is the position of +a%, the waveform 320 is the control signal PWM (pulse width modulation) duty ratio 50-a% sent by the main control unit 140, the horizontal stripe block 322 is the position of-a%, the waveform 330 is the control signal PWM (pulse width modulation) duty ratio 50% sent by the main control unit 140, the waveform 310 magnetizes the magnetic core 111 with more than the magnetizing time of the horizontal stripe block 314, the waveform 320 magnetizes the magnetic core 111 with less magnetizing time of the horizontal stripe block 314, the average magnetizing time of the waveform 310 and the waveform 312 is equivalent to the magnetizing and discharging effect of the magnetic core 111 by the waveform 330, that is the two magnetic fluxes are mixed, and the total magnetizing and discharging effects are also achieved.

Further, it is noted that, if the difference in duty ratio from the packet with the highest average voltage corresponding to waveform 310 to the packet with the lowest average voltage corresponding to waveform 320 is twice a%, the upper limit of a% can be increased if the equalization time of the system specification of the cell 120 is found to be too long, but it is recommended to change the frequency and the inductance-capacitance value as much as possible to adjust the current, instead of fully utilizing the difference in duty ratio to accelerate, so the preferred maximum of a% in the embodiment of the present invention is 10%, so as to improve the stability of the system.

Because the Continuous Conduction (CCM) is adopted, the current continuously increases and decreases in the winding groups 112, and for example, a% = 10% is used as an example, the current of the winding group 112 corresponding to each single cell 120 is increased by 60% of time, the current flows back to the cell 120 by 40% of time, the current of the corresponding cell 120 is reduced by less time because of more output time, otherwise, the voltage of the cell 120 with the lowest voltage is increased by 40% of time, the current flows back to the cell 120 by 60% of time, and the current is reduced by 60% of time, so that the voltage of the corresponding cell 120 is rapidly increased, and the effect of rapid active equalization is achieved by the duty ratio difference.

To implement the principle of the duty cycle of the bandwidth modulation in fig. 3a, the current corresponding to the control timing is illustrated, as shown in fig. 3b, a current schematic diagram corresponding to the control timing is shown, the current shown in fig. 3b is not divided, only the continuous change of the current in the CCM mode is shown, and the result of the current change is that although the energy of the battery pack with the highest average voltage in the battery cell 120 group is quickly transferred to the battery pack with the lowest average voltage in the battery cell 120 group with the difference of the duty cycle of the bandwidth modulation, and the two currents are balanced, that is, the magnetic flux in the magnetic core 111 will not increase. The current of the winding 112 continues to increase in each of the different directions. In fig. 3b, waveform 340 is the control waveform corresponding to the group of cells in the group of cells 120 having the highest average voltage, and as described above, the positive half-cycle width modulation duty cycle of the magnetization of waveform 340 is 50% + a%, cross grain block 342 is the +a% position, waveform 350 is the control waveform corresponding to the group of cells in the group of cells 120 having the lowest average voltage, the positive half-cycle duty cycle of the magnetization of waveform 350 is 50% -a%, cross grain block 352 is the-a% position, so the difference in the two duty cycle modulation duty cycles is 2a%, which is equal to the transfer of energy from diagonal grain block 344 to diagonal grain block 354. The waveform 360 is a waveform of the charge-discharge current corresponding to the control timing waveform 340, the dotted line 362 is a magnetizing current, that is, the magnitude of the current flowing out from the positive electrode of the battery cell 120, the dotted line 364 is a discharging current, that is, the magnitude of the current flowing back to the positive electrode of the battery cell 120, and since the winding 112 is an inductor in high frequency, the magnetizing and discharging current is a waveform of the battery cell 120 charged and discharged in high frequency through the inductor, the magnitude of the current is continuous, and since the time of the waveform 362 is longer than that of the waveform 364, the current flowing out in one PWM period is more than the current flowing back, and the accumulated result is that the current is increasingly larger. While waveform 370 is a waveform of the charge-discharge current corresponding to the control timing waveform 350, the dashed line 372 is a magnetizing current, that is, the magnitude of the current flowing outwards from the positive electrode of the battery cell 120, the dashed line 374 is a discharging current, that is, the magnitude of the current flowing back to the positive electrode of the battery cell 120, as described above, the waveform of the battery cell 120 through inductance in high-frequency charging-discharging is changed from half to half in the tap winding group 112, the lines are connected together, the current magnitude is continuous, but the current flowing direction of the current to the positive electrode of the battery cell 120 is opposite, fig. 3b only shows the absolute magnitude, without directionality, and then fig. 3c only increases directionality, because the time ratio 374 of the waveform 372 is short, so that the current flowing out in one PWM period is less than the current flowing back, and the accumulated result is that the current is increasingly smaller.

In fig. 3b, when the control sequence in fig. 3a is implemented, the current is not split, and in fig. 3c, the current in the tap winding 112 is magnetized in the direction of the positive output current of the battery core 120, the direction of the magnetic induction current discharged from the magnetic core 111 to flow back to the positive electrode of the battery core 120 is negative, so that the current in the real coil, i.e. the winding 112 in fig. 3b is redrawn.

In fig. 3c, the definition of fig. 3b is followed, the waveform 340 is the control waveform corresponding to the group with the highest average voltage of the battery cells 120, the waveform 360a is the control waveform corresponding to the group with the lowest average voltage of the battery cells 120, the waveform 370a is the charge current corresponding to the control waveform 350, as described before 362 is the charge current, the discharge current 364 jumps from the waveform 362 to the position with equal current magnitude at one moment in the current switching direction, but in the opposite direction, the charge current waveform 362 is divided into two parts 362a and 362b again, similarly 372 is the charge current, the discharge current 374 jumps from the waveform 372 to the position with equal current magnitude at one moment in the current switching direction, but in the opposite direction, the waveform 370 is divided into two parts of 374a and 374b again, when the waveform 370 is switched to the discharge current by the charge current, the waveform 360 is still at the moment in the current switching direction, the waveform 362 jumps from the waveform 362 to the equal current magnitude at one moment, but does not decrease, the discharge current of the waveform 362b is not reduced, the magnetic flux of the waveform is not reduced until the waveform 362b is not reduced, and the magnetic flux of the waveform 374a is not reduced, and the magnetic flux of the waveform is not reduced, and the waveform 374b is gradually reduced, and the magnetic flux is not the magnetic flux is blown back to the waveform is gradually after the waveform is blown off, and the waveform is reduced.

From fig. 3c, it is found that the original waveform 374 moves to waveform 374a and waveform 374b, so the integration region of the return current increases the charge (q=i×Δt) of the vertical diamond 376, that is, the energy transferred from the battery with the highest average voltage to the battery with the lowest average voltage by using the difference in the duty cycle of the wave width modulation. Since the average time of magnetizing and discharging of the two groups of cells 120 is equal to 50%, the magnetic flux does not continuously increase, but the current in the winding coil corresponding to the group of cells with the highest average voltage among the groups of cells 120 increases, which indicates that although the magnetic energy is transferred from the group of cells with the highest average voltage to the group of cells with the lowest average voltage in the second control timing with 2a% of time, the residual current exists in the winding group, instead of actually transferring 2a% of the magnetic flux and the magnetic energy, the magnetic energy less than 2a% is transferred. Thus, the next adjustment is performed, see fig. 3d. As shown in fig. 3d, the control waveform 340 is replaced by waveform 380 in fig. 3d, while waveform 350 is replaced by waveform 390, waveforms 362,364 a, 264 b,374a,374b follow the definition in fig. 3c, and as described above, the residual current still exists in the third control sequence, and must be cleared to achieve the actual automatic magnetic reset, which is 364a. Next, the clear waveform 364a is specifically explained, because the characteristics of the inductance and inductance, when the frequency and the load are unchanged, the current magnitude and the speed of the current change will be continuous, so it can be seen from fig. 3d that the waveform 364 must be continuously extended for 2a% (corresponding to the clear waveform 364 a) to be cleared, the waveform of the fourth control timing (t 3-t 4) is marked with 364a, that is, the duty cycle of the fourth control timing (t 3-t 4) is continuously extended for 2a% from the t3 time point, the clear time point is the t4 time point, the specific t4 time point will be changed along with the influence of the MOS switch, the winding set and the stray parameter of the transformer, and the current in the winding set can be finely adjusted in the experimental process, so as to achieve the purpose of truly and automatically resetting.

Each waveform in fig. 3d defines a time point t0, t1, & gt, t5=t0, starting from the left t0, magnetizing current waveform 362 is identical to waveform 372 and ending with the one period of fig. 3c until time t3 (i.e., the third control timing of the control period) is the same as before, the half period of the discharging of waveform 380 for modifying the discharging control of the battery pack with the highest average voltage in the battery cells 120 is divided into three parts of 382a,382b,382c, 382a is identical to the discharging before, but the discharging is not ended until time t3 (i.e., the third control timing of the control period) is reached, the discharging is ended until time t4 (i.e., the fourth control timing of the control period) is reached after waveform 382b continues discharging 2a%, then, a waveform 382c can turn off the MOS tube after being magnetized and demagnetized from t4 to t5 in a very short turn-off time, the next period can be started after t5, if continuous operation is performed, t0 of the next period is equal to t5 of the previous period, the half period of the waveform 390 is divided into two parts of 39a and 39b, 392a is magnetized as before, and the magnetization is finished until t3 (i.e. the third control time sequence of the control period), but the MOS tube after being magnetized and demagnetized from t3 (i.e. the third control time sequence of the control period) is turned off at 392b, and the magnetization and demagnetization is finished from t3 to t 5.

In fig. 3b, waveform 360 is switched from waveform 364 to waveform 362 for magnetizing at time t3, so that the current increases, and the modification in fig. 3d is to lengthen waveform 364a from time t3 (i.e., the third control timing of the control period) to time t4 (i.e., the fourth control timing of the control period), which is exactly 2a% of the time, so that the positive electrode of cell 120 of waveform 360 outputs current for 50% + a% of the time, and the current recharging takes place for the positive electrode of cell 120 for 50% + a% of the time, so that the current flowing from the positive electrode of cell 120 is as much as the current flowing in. The waveform 370a is originally zeroed from t0 to t3 (i.e. the third control time sequence of the control period), so that the magnetizing and demagnetizing MOS tubes are turned off from t3 to t5, and the magnetic flux change caused by the current backflow of the waveform 360a is not involved.

Specifically, t0-t1 is the (50-a)% duty cycle of the first control timing, and the battery pack with the highest average voltage is magnetized, and the battery pack with the lowest average voltage is magnetized; t1-t2 is the duty ratio of 2a% of the second control time sequence, the battery pack with the highest average voltage is magnetized, and the battery pack with the lowest average voltage is magnetized; t2-t3 is the third control time sequence, namely (50-a)% duty ratio, the battery pack with the highest average voltage is demagnetized, and the battery pack with the lowest average voltage is demagnetized, so that the magnetizing and the demagnetizing of t0-t3 cancel each other. Although the magnetic flux is not continuously increased after the magnetization and the demagnetization are counteracted, the current of the battery pack with the highest average voltage is increased, so that the switch state of the battery pack with the highest average voltage and the battery pack with the lowest average voltage are processed by the time of the fourth control time sequence, wherein t3-t4 is necessary to be increased; however, the current of the battery pack with the highest average voltage is not lightened, the battery pack with the highest average voltage from t3 to t4 continues to be magnetized until no current exists, and the battery pack with the lowest average voltage turns off the current during the period, and is not magnetized and not magnetized.

In further detail, in the embodiment of the present invention, there are 6 key time points t0, t1, t2 in each complete magnetizing and discharging control period, where t5, t5 may start the next period, so t5 may be regarded as t0 of the next period, where the first to fourth control timings t0-t4 are 100%, the fifth control timings t4-t5 are additional adjustment periods, the duty cycle is still calculated with t0-t4 as 100% of the time length, and t4-t5 are optional timings, because the processing speed of some master units 140 is not fast enough to immediately enter the next control period, and the fifth control timing may be added here to wait for the master units 140 to start a new period, and in addition, the time of the ADC described above is also performed in the fifth control timing. The control timing of the control cycle is specifically described below:

In the first control sequence t0-t1, the main control unit 140 controls the battery pack with the highest average voltage to be magnetized, and the battery pack with the lowest average voltage to be magnetized;

In the second control time sequence t1-t2, the main control unit 140 controls the battery pack with the highest average voltage to be magnetized and controls the battery pack with the lowest average voltage to be magnetized;

In the third control sequence t2-t3, the main control unit 140 controls the battery pack with the highest average voltage to discharge magnetism, and the battery pack with the lowest average voltage to discharge magnetism;

In the fourth control sequence t3-t4, the main control unit 140 controls the battery pack with the highest average voltage to be demagnetized, and the battery pack with the lowest average voltage is not magnetized;

The time length of t0-t3 is taken as 100%, the master control unit in the fourth control time sequence t3-t4 controls the battery pack with the highest average voltage to demagnetize, and the battery pack with the lowest average voltage is turned off. And in the fifth control time sequence t4-t5, the main control unit controls the battery pack with the highest average voltage to be turned off, and the battery pack with the lowest average voltage to be turned off.

In a complete magnetizing and discharging control period, the battery pack with the highest average voltage and the lowest average voltage are magnetized together to the battery core in a first control time sequence, the battery pack with the highest average voltage is continuously magnetized in a second control time sequence, the battery pack with the lowest average voltage starts to discharge magnetism, so that the energy of the battery pack with the highest average voltage is conveyed to the battery pack with the lowest average voltage, the battery pack with the highest average voltage and the lowest average voltage are discharged from the magnetic core together to form electric energy in a third control time sequence, the battery pack with the highest average voltage is continuously discharged to the current return to zero in a fourth control time sequence, and the battery pack with the lowest average voltage is not involved in discharging magnetism because the current is already returned to zero.

Referring to fig. 4 and fig. 5, the embodiment of the present invention further provides a control method for actively balancing a battery, where the method is applied to any one of the above control systems for actively balancing a battery, as shown in fig. 1a, fig. 1b and fig. 2, where the control system for actively balancing a battery includes a transformer 110, an analog-to-digital converter 130, a main control unit 140, N electric cores 120, and 2N switch circuits 150; the transformer 110 includes a magnetic core 111 and N tapped winding groups 112 wound around the magnetic core 111, and the N electric cores 120 are divided into i battery groups, i being an integer greater than or equal to 2. As shown in fig. 4, the method comprises the steps of:

410. The main control unit 140 collects the voltage of each cell 120 of the N cells 120 through the analog-to-digital converter 130;

420. The main control unit 140 calculates an average voltage of each of the i battery packs;

430. The main control unit 140 confirms the battery pack with the highest average voltage and the battery pack with the lowest average voltage, and controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be greater than 50% when the first switch circuit 151 correspondingly connected to each cell 120 in the battery pack with the highest average voltage is conducted to magnetize, and controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be less than 50% when the second switch circuit 152 correspondingly connected to each cell 120 in the battery pack with the highest average voltage is conducted to magnetize, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at a wave width modulation duty ratio which is 2a% greater than the battery pack with the lowest average voltage; and, the main control unit 140 controls the bandwidth modulation duty ratio of each battery cell 120 in the battery pack with the lowest average voltage to be less than 50% when the first switch circuit 151 correspondingly connected to the battery pack is turned on for magnetizing, and controls the bandwidth modulation duty ratio of each battery cell 120 in the battery pack with the lowest average voltage to be greater than 50% when the second switch circuit 152 correspondingly connected to the battery pack with the lowest average voltage is turned on for discharging, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy at a bandwidth modulation duty ratio which is 2a% greater than that of the battery pack with the highest average voltage.

Preferably, the magnitude of a% is in direct proportion to the difference between the highest average voltage and the lowest average voltage, and after the master control unit 140 confirms the battery pack with the highest average voltage and the battery pack with the lowest average voltage, the method further comprises:

The main control unit 140 calculates a difference value of the highest value and the lowest value of the average voltage;

the main control unit 140 calculates a% according to the difference value between the highest average voltage value and the lowest average voltage value; wherein a% = (average voltage highest value-average voltage lowest value)/preset voltage equivalent, the preset voltage equivalent is used for adjusting the bandwidth modulation duty cycle.

Preferably, the method further comprises:

The main control unit 140 determines whether a% is greater than a preset fixed percentage, and determines that a% is the preset fixed percentage when a% is greater than the preset fixed percentage, wherein the preset fixed percentage is within a preset range of +/-10%.

Preferably, the method further comprises:

the main control unit 140 controls the duty ratio of the wave width modulation when the first switching circuit 151, which is correspondingly connected to each of the battery cells 120 in the battery pack except the battery pack having the highest average voltage and the battery pack having the lowest average voltage, is turned on to perform magnetization to be 50%, and controls the duty ratio of the wave width modulation when the second switching circuit 152, which is correspondingly connected to each of the battery cells 120 in the battery pack having the highest average voltage and the battery pack having the lowest average voltage, is turned on to perform magnetization to be 50%.

Preferably, the method further comprises:

The main control unit 140 controls the preset bandwidth modulation duty ratio of 50% when the first switching circuit 151, which is not connected to each of the battery cells 120 in the battery pack corresponding to the comparison average voltage, is turned on to perform magnetization, and controls the preset bandwidth modulation duty ratio of 50% when the second switching circuit 152, which is not connected to each of the battery cells 120 in the battery pack corresponding to the comparison average voltage, is turned on to perform magnetization.

Preferably, the method further comprises:

When the difference value between the highest average voltage value and the lowest average voltage value becomes larger, the main control unit 140 reduces the adjusting frequency of the bandwidth modulation duty ratio so as to improve the current of the system during active equalization and further accelerate the speed of active equalization;

When the difference between the highest average voltage value and the lowest average voltage value becomes smaller, the main control unit 140 increases the adjusting frequency of the duty ratio of the wave width modulation, so as to reduce the current of the system during active equalization and further increase the stability of the active equalization.

Preferably, the method further comprises:

the main control unit 140 performs linear programming by taking the difference between the highest adjusting frequency and the lowest adjusting frequency of the bandwidth modulation duty ratio preset by the system as an adjusting target of 100%;

The main control unit 140 calculates an adjustment percentage of the adjustment frequency of the bandwidth modulation duty cycle, wherein the adjustment percentage b% of the adjustment frequency of the bandwidth modulation duty cycle is the voltage equivalent of the adjustment frequency of the bandwidth modulation duty cycle, which is obtained by dividing the difference between the highest average voltage value and the lowest average voltage value by the preset voltage equivalent of the system.

Preferably, the method further comprises:

The main control unit 140 determines that the difference between the highest average voltage value and the lowest average voltage value is greater than the voltage equivalent of the regulating frequency of the preset wave width modulation duty cycle of the system, and the regulating frequency of the wave width modulation duty cycle is the lowest regulating frequency of the preset wave width modulation duty cycle of the system;

when the main control unit 140 determines that b% is less than or equal to 5%, the adjusting frequency of the bandwidth modulation duty cycle is the highest adjusting frequency of the bandwidth modulation duty cycle preset by the system;

When the master control unit 140 determines that b% is greater than 5%, calculating the adjustment frequency of the bandwidth modulation duty cycle by adopting a linear interpolation manner, and obtaining an updated adjustment frequency freq_b% of the bandwidth modulation duty cycle, where freq_b% = highest adjustment frequency-b%. Of the bandwidth modulation duty cycle preset by the system (highest adjustment frequency of the bandwidth modulation duty cycle preset by the system-lowest adjustment frequency of the bandwidth modulation duty cycle preset by the system).

As shown in fig. 5, an embodiment of the present invention provides another control method for actively balancing a battery, including the following steps:

510. Initializing, and setting an active equalization flag to zero;

511. Reading the cell 120 voltage by the ADC;

512. calculating an average voltage of each battery pack;

513. Comparing the average voltages of all the battery packs, determining the battery pack with the highest average voltage and the battery pack with the lowest average voltage, and calculating the difference between the highest cell 120 voltage and the lowest cell 120 voltage;

520. It is determined whether the value of the active equalization flag is 1 or 0.

If the value of the active equalization flag is 1, the following step 521 is performed, and if the value of the active equalization flag is 0, the following step 530 is performed.

521. If the value of the active equalization flag is 1, it is determined whether the difference between the highest cell 120 voltage and the lowest cell 120 voltage is less than a preset threshold value for ending equalization control.

Ending the equalization control if the difference between the highest cell 120 voltage and the lowest cell 120 voltage is less than a preset threshold value for ending the equalization control; if the difference between the highest cell 120 voltage and the lowest cell 120 voltage is not less than the preset threshold value for ending the equalization control, the following step 522 is performed.

522. The main control unit 140 controls the battery pack having the highest average voltage to convert electric energy into magnetic energy at a duty cycle of 2a% more wave width modulation, and the main control unit 140 controls the battery pack having the lowest average voltage to convert magnetic energy into electric energy at a duty cycle of 2a% more wave width modulation. The implementation of step 522 may be specifically referred to the specific implementation details of step 430 described above.

530. If the value of the active equalization flag is 0, it is determined whether the difference between the highest cell 120 voltage and the lowest cell 120 voltage is greater than a preset threshold value for starting equalization control.

If the difference between the highest cell 120 voltage and the lowest cell 120 voltage is greater than the preset threshold for starting the equalization control, the following step 531 is performed, and if the difference between the highest cell 120 voltage and the lowest cell 120 voltage is not greater than the preset threshold for starting the equalization control, the following step 511 is performed again, and the cell 120 voltage of the next round is read.

531. If the difference between the highest cell 120 voltage and the lowest cell 120 voltage is greater than the preset threshold to initiate equalization control, the active equalization flag is set to a value of 1. Then, active equalization control is continued, i.e., the above-described step 522 is performed, and details of step 522 are as follows:

After performing step 522 to implement the active equalization control, step 540 is further performed to determine whether the time for the ADC to sample and read the voltage of the battery cell 120 is reached, if so, step 511 is performed back to read the voltage of the battery cell 120, and if not, step 522 is performed to implement the active equalization control, and specific implementation details of step 522 may refer to specific implementation details of step 430.

In the embodiment shown in fig. 5, in step 521, "if the value of the active equalization flag is 1, it is determined whether the difference between the highest cell 120 voltage and the lowest cell 120 voltage is less than the preset threshold for ending the equalization control" is true to determine whether to stop the active equalization, if the difference between the highest cell 120 voltage and the lowest cell 120 voltage is less than the preset threshold for ending the equalization control, the preset threshold for ending the equalization control is preferably selected to be 2mV to 20mV.

In order to correctly determine whether to restart the active equalization, the above step 530 is implemented by determining whether the difference between the highest cell 120 voltage and the lowest cell 120 voltage is greater than the preset threshold value for starting the equalization control if the value of the active equalization flag is 0, performing the following step 531 to set the value of the active equalization flag to 1 to start the equalization control if the difference between the highest cell 120 voltage and the lowest cell 120 voltage is greater than the preset threshold value for starting the equalization control, and performing the following step 511 if the difference between the highest cell 120 voltage and the lowest cell 120 voltage is not greater than the preset threshold value for starting the equalization control, and then reading the cell 120 voltage of the next round to again determine whether to start the equalization control. Preferably, the preset threshold value for starting the equalization control is 2 to 5 times the preset threshold value for ending the equalization control.

In the above active balancing process, the present invention further provides a control method for actively balancing the batteries, mainly comprising controlling the magnetizing and the discharging according to step 522 by adjusting the duty ratio of the bandwidth modulation of the two battery groups with the highest average voltage and the lowest average voltage, so as to achieve the purpose of transferring energy from the battery 120 group with the high average voltage to the battery 120 group with the low average voltage, wherein the method comprises a method for adjusting the duty ratio of the bandwidth modulation of the two groups with the lowest average voltage and the highest average voltage in the i battery groups according to the difference between the highest average voltage and the lowest average voltage, and a method for adjusting the frequency of the pulse modulation, and the method is as described in step 430.

Further details of the implementation of step 522 described above are illustrated in fig. 6, including the following steps:

610. The main control unit 140 calculates a difference value of the highest value and the lowest value of the average voltage;

611. the main control unit 140 calculates a% according to the difference value between the highest average voltage value and the lowest average voltage value; wherein a% = (average voltage highest value-average voltage lowest value)/preset voltage equivalent, the preset voltage equivalent is used for adjusting the bandwidth modulation duty cycle. Preferably, a% is determined by taking the difference between the highest value of the average voltage and the lowest value of the average voltage to be 1% per 20mV, and in this embodiment, the voltage equivalent of this preset adjustment duty cycle is 2V, that is, every 20 mv=1%.

612. The a% was taken as 4 house 5.

In addition, when the difference between the highest average voltage value and the lowest average voltage value becomes larger, the main control unit 140 reduces the adjusting frequency of the duty ratio of the wave width modulation, so as to increase the current of the system during active equalization and further increase the speed of active equalization; when the difference between the highest average voltage value and the lowest average voltage value becomes smaller, the main control unit 140 increases the adjusting frequency of the duty ratio of the wave width modulation, so as to reduce the current of the system during active equalization and further increase the stability of the active equalization.

Therefore, the adjustment frequency of the wave width modulation duty ratio is in a linear programming relation with the difference value between the highest average voltage value and the lowest average voltage value, and the linear programming relation is calculated to obtain an adjustment percentage b% of the pulse width modulation frequency. Preferably, the main control unit 140 performs linear programming by taking the difference between the highest adjusting frequency and the lowest adjusting frequency of the bandwidth modulation duty cycle preset by the system as an adjusting target of 100%; the main control unit 140 calculates an adjustment percentage of the adjustment frequency of the bandwidth modulation duty cycle, wherein the adjustment percentage b% of the adjustment frequency of the bandwidth modulation duty cycle is the voltage equivalent of the adjustment frequency of the bandwidth modulation duty cycle, which is obtained by dividing the difference between the highest average voltage value and the lowest average voltage value by the preset voltage equivalent of the system.

Specific implementation details of the frequency of adjustment of the bandwidth modulation duty cycle during active equalization are described below in conjunction with steps 613-614.

613. The main control unit 140 determines whether a% is greater than a preset fixed percentage, and determines that a% is the preset fixed percentage when a% is greater than the preset fixed percentage, wherein the preset fixed percentage is within a preset range of +/-10%. If a% is not greater than the preset fixed percentage, then the following step 614 is performed.

614. The main control unit 140 performs linear programming by taking the difference between the highest adjusting frequency and the lowest adjusting frequency of the bandwidth modulation duty cycle preset by the system as an adjusting target of 100%, and the main control unit 140 calculates the adjusting percentage of the adjusting frequency of the bandwidth modulation duty cycle, wherein the adjusting percentage b% of the adjusting frequency of the bandwidth modulation duty cycle is the voltage equivalent of the adjusting frequency of the bandwidth modulation duty cycle preset by the system divided by the difference between the highest value and the lowest value of the average voltage. The preferred voltage equivalent of the tuning frequency of the preset tuning bandwidth modulation duty cycle of this system is 1V, i.e. every 10 mv=1%.

615. B% was taken as 4 house 5.

620. Judging whether b% is equal to or greater than 100%;

If b+.gtoreq.100%, then step 621 is performed. If b+.gtoreq.100%, that is, the difference between the highest average voltage value and the lowest average voltage value is greater than the voltage equivalent of the adjusting frequency of the preset bandwidth modulation duty cycle of the system, the adjusting frequency of the bandwidth modulation duty cycle is the lowest adjusting frequency of the bandwidth modulation duty cycle of the system. If b% is not equal to or greater than 100%, step 630 is performed to determine if b% is equal to or less than 5%, and if b% is equal to or less than 5%, step 631 is performed. If b% is not less than or equal to 5% and not more than or equal to 100%, then step 640 is performed.

621. Setting b% as 100% and setting the adjusting frequency freq_b% of the bandwidth modulation duty cycle as the lowest adjusting frequency of the bandwidth modulation duty cycle preset by the system. In step 621, the lower limit of the adjustment frequency of the bandwidth modulation duty cycle is preferably limited, in a specific implementation, it may be determined whether b% obtained in step 615 is greater than 100%, and if b% is greater than 100%, b% is set to 100%, so that the lowest value of the adjustment frequency of the bandwidth modulation duty cycle is limited, that is, when the difference between the highest average voltage value and the lowest average voltage value is greater than the voltage equivalent of the adjustment frequency of the preset adjustment bandwidth modulation duty cycle, the frequency is fixed at the lowest adjustment frequency of the bandwidth modulation duty cycle preset by the system.

631. The main control unit 140 determines that b% is less than or equal to 5%, and the adjustment frequency freq_b% of the bandwidth modulation duty cycle is the highest adjustment frequency of the bandwidth modulation duty cycle preset by the system. In step 631, if b% is less than or equal to 5%, the adjustment frequency freq_b% of the pwm duty cycle is set to the preset maximum pwm frequency.

640. When the master control unit 140 determines that b% is greater than 5%, calculating the adjustment frequency of the bandwidth modulation duty cycle by adopting a linear interpolation manner, and obtaining an updated adjustment frequency freq_b% of the bandwidth modulation duty cycle, where freq_b% = highest adjustment frequency-b%. Of the bandwidth modulation duty cycle preset by the system (highest adjustment frequency of the bandwidth modulation duty cycle preset by the system-lowest adjustment frequency of the bandwidth modulation duty cycle preset by the system).

In the embodiment of the present invention, when the master control unit 140 determines that b% is greater than 5% and less than 100%, the adjustment frequency of the bandwidth modulation duty cycle is calculated by adopting a linear interpolation manner, so as to obtain the updated adjustment frequency freq_b% of the bandwidth modulation duty cycle, where freq_b% = highest adjustment frequency-b% + of the bandwidth modulation duty cycle preset by the system (highest adjustment frequency of the bandwidth modulation duty cycle preset by the system) is calculated.

The preferred minimum tuning frequency of the system preset bandwidth modulation duty cycle is from 10kHz to 30kHz, and the highest tuning frequency of the system preset bandwidth modulation duty cycle is from 50kHz to 200kHz.

As shown in fig. 7, 4 waveforms in fig. 7 are illustrative of changing the equalizing current size by the adjustment percentage b% of the adjustment frequency of the bandwidth modulation duty cycle, the waveform 710 is a control signal PWM (pulse width modulation) waveform of the lowest adjustment frequency of the bandwidth modulation duty cycle where freq_b% is preset, the waveform 720 is a control signal PWM (pulse width modulation) waveform of the highest adjustment frequency of the bandwidth modulation duty cycle where freq_b% is preset, the current waveform such as the waveform 712 corresponding to the waveform 710 at the lowest bandwidth modulation frequency, and the current waveform such as the waveform 722 corresponding to the waveform 720 at the lowest adjustment frequency of the bandwidth modulation duty cycle, because the voltage of the battery 120 and the inductance of the winding 112 are the same, the slope of the current rising and falling becomes the same, but the amplitude of the current rising and falling becomes large when the frequency is low, and the amplitude of the current rising and falling becomes small when the frequency is high, which is the principle of the current modulation is used for adjusting the frequency.

Preferably, the method further comprises:

The main control unit 140 controls the bandwidth modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a first control timing in the control period, controls the bandwidth modulation duty ratio of the battery pack with the highest average voltage to be 2a% when the battery pack with the highest average voltage is magnetized at a second control timing, and controls the bandwidth modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a third control timing, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at a bandwidth modulation duty ratio which is more than that of the battery pack with the lowest average voltage by 2 a%; the first control timing sequence, the second control timing sequence, and the third control timing sequence of the control period are continuous;

After calculating the average voltage of each of the i battery packs, the master control unit 140 controls the 2N switch circuits 150 to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be less than 50% (50-a)%, to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be 2a% when the battery pack with the lowest average voltage is magnetized at the second control timing of the control period, and to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be (50-a)%, when the battery pack with the lowest average voltage is magnetized at the third control timing of the control period, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy at a bandwidth modulation duty ratio that is more than the battery pack with the highest average voltage by 2 a%. And, the main control unit 140 controls the battery pack with the highest average voltage to perform magnetization in the fourth control time sequence in the control period until the magnetization current is over, and controls the battery pack with the lowest average voltage to stop magnetization and magnetization in the fourth control time sequence in the control period; the first control timing, the second control timing, the third control timing, and the fourth control timing of the control period are consecutive.

In this embodiment, the implementation of the first control timing, the second control timing, the third control timing, and the fourth control timing of the control period may refer to the above-mentioned examples of fig. 3a to 3d, and are not described herein. The invention provides a control system and a method for actively balancing batteries, wherein the system comprises a main control unit 140, wherein the main control unit 140 calculates the average voltage of each battery pack in i battery packs, controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be more than 50% when the battery pack is magnetized and controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be less than 50% when the battery pack is magnetized, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy with the wave width modulation duty ratio which is 2a% more than the battery pack with the lowest average voltage; the device is also used for controlling the wave width modulation duty ratio of the battery pack with the lowest average voltage to be less than 50% when the battery pack with the lowest average voltage is magnetized and controlling the wave width modulation duty ratio of the battery pack with the lowest average voltage to be more than 50% when the battery pack with the lowest average voltage is magnetized so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy at the wave width modulation duty ratio which is 2a% more than the battery pack with the highest average voltage. The system realizes active equalization at a higher speed than semi-active equalization, so that the total energy consumption and heat of the system are reduced along with the reduction of active equalization time, and the service life of the system is prolonged.

In the description of the present invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "another end," "upper," "one side," "top," "inner," "front," "center," "two ends," etc. indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," "fourth," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, whereby features defining "first," "second," "third," "fourth" may explicitly or implicitly include at least one such feature. In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "configured," "connected," "secured," "screwed," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intermediaries, or in communication with each other or in interaction with each other, unless explicitly defined otherwise, the meaning of the terms described above in this application will be understood by those of ordinary skill in the art in view of the specific circumstances. It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that the present invention is described in detail with reference to the foregoing embodiments, and modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A control system for active equalization of batteries, comprising:

A transformer comprising N tapped winding sets; and

The system further comprises: n electric cores which are connected with N taps of the N tapped winding groups of the transformer in a one-to-one correspondence manner; and

The system also comprises an analog-to-digital converter, a main control unit and 2N switch circuits; and

The transformer is connected with the 2N switch circuits in a one-to-one correspondence manner through 2N non-extraction ends of the transformer, the 2N switches are divided into N switch groups, each switch group comprises two switch circuits, and the N switch groups are connected with the N electric cores in a one-to-one correspondence manner;

The N electric cores are divided into i battery packs, wherein i is an integer greater than or equal to 2;

the analog-to-digital converter comprises N paths of input ends, and the N paths of input ends of the analog-to-digital converter are connected with the N electric cores in a one-to-one correspondence manner;

the main control unit is connected with the analog-to-digital converter so as to collect the voltage of each of the N electric cores through the analog-to-digital converter;

The main control unit is connected with the 2N switch circuits, and is further used for calculating the average voltage of each battery pack in the i battery packs, controlling the battery pack with the highest average voltage to be magnetized to have a wave width modulation duty ratio of more than 50 percent (50+a)%, and controlling the battery pack with the highest average voltage to be magnetized to have a wave width modulation duty ratio of less than 50 percent (50-a)%, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy with a wave width modulation duty ratio which is more than 2a percent;

The main control unit is further configured to control, after calculating the average voltage of each of the i battery packs, the 2N switch circuits to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be less than 50% (50-a)%, and to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be greater than 50% (50+a)%, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy with a bandwidth modulation duty ratio of more than 2 a%.

2. The control system for active equalization of a battery of claim 1, wherein said a% magnitude is proportional to the difference between the highest average voltage and the lowest average voltage;

The a% = (average voltage highest value-average voltage lowest value)/a preset voltage equivalent, wherein the preset voltage equivalent is used for adjusting the bandwidth modulation duty ratio;

3. The control system for actively equalizing a battery according to claim 1, wherein the main control unit is further configured to control a bandwidth modulation duty ratio when the battery pack having the highest average voltage and the battery packs other than the battery pack having the lowest average voltage are magnetized to be 50%, and control a bandwidth modulation duty ratio when the battery pack having the highest average voltage and the battery packs other than the battery pack having the lowest average voltage are magnetized to be 50%;

The main control unit is further configured to control a preset bandwidth modulation duty ratio of 50% when the battery pack not participating in comparing the average voltage with the average voltage is magnetized, and control the preset bandwidth modulation duty ratio of 50% when the battery pack not participating in comparing the average voltage with the average voltage is magnetized.

4. The control system for active equalization of a battery of claim 2, wherein,

The main control unit is further used for reducing the adjusting frequency of the bandwidth modulation duty ratio when the difference value between the highest average voltage value and the lowest average voltage value is larger, so as to improve the current of the system during active equalization and further speed up the active equalization;

The main control unit is further used for improving the adjusting frequency of the bandwidth modulation duty ratio when the difference value between the highest average voltage value and the lowest average voltage value is smaller, so as to reduce the current of the system during active equalization and further improve the stability of the active equalization;

And the regulating frequency of the wave width modulation duty ratio is in a linear planning relation with the difference value between the highest value of the average voltage and the lowest value of the average voltage, the difference value between the highest regulating frequency and the lowest regulating frequency of the wave width modulation duty ratio preset by the system is used as a regulating target of 100%, the regulating percentage of the regulating frequency of the wave width modulation duty ratio is that the difference value between the highest value of the average voltage and the lowest value of the average voltage is divided by the voltage equivalent of the regulating frequency of the wave width modulation duty ratio preset by the system, and when the regulating percentage of the regulating frequency of the wave width modulation duty ratio is <5%, the regulating frequency of the wave width modulation duty ratio is the highest regulating frequency of the wave width modulation duty ratio preset by the system.

5. The control system for active equalization of a battery of claim 1, wherein,

The main control unit is further used for controlling the bandwidth modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a first control time sequence in a control period, controlling the bandwidth modulation duty ratio of the battery pack with the highest average voltage to be 2a% when the battery pack with the highest average voltage is magnetized at a second control time sequence, and controlling the bandwidth modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a third control time sequence, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at a bandwidth modulation duty ratio which is more than 2 a%; the first control timing sequence, the second control timing sequence, and the third control timing sequence of the control period are continuous;

The master control unit is further configured to calculate an average voltage of each of the i battery packs, and then control, by controlling the 2N switch circuits, a bandwidth modulation duty ratio of the battery pack with the lowest average voltage when the first control timing in the control period is magnetizing to be less than 50% (50-a), a bandwidth modulation duty ratio of the battery pack with the lowest average voltage when the second control timing in the control period is magnetizing to be 2a%, and a bandwidth modulation duty ratio of the battery pack with the lowest average voltage when the third control timing in the control period is magnetizing to be (50-a), so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy with a bandwidth modulation duty ratio of 2a% more than the bandwidth modulation duty ratio of the battery pack with the lowest average voltage when the second control timing and the third control timing in the control period;

the main control unit is also used for controlling the battery pack with the highest average voltage to perform magnetism release in a fourth control time sequence in the control period until the magnetism release current is finished; the main control unit is also used for controlling the battery pack with the lowest average voltage to stop magnetizing and discharging in the fourth control time sequence in the control period; the first control timing, the second control timing, the third control timing, and the fourth control timing of the control period are consecutive.

6. A control method for actively balancing a battery, wherein the method is applied to the control system for actively balancing a battery according to any one of claims 1 to 5, the system comprises a transformer, and the transformer comprises a winding group with N taps; the system further comprises N electric cores which are connected with N taps of the N tapped winding groups of the transformer in a one-to-one correspondence manner, the system further comprises an analog-to-digital converter, a main control unit and 2N switch circuits, the transformer is connected with the 2N switch circuits in a one-to-one correspondence manner through 2N non-tap ends of the transformer, the 2N switches are divided into N switch groups, each switch group comprises two switch circuits, the N switch groups are connected with the N electric cores in a one-to-one correspondence manner, and the main control unit is connected with the 2N switch circuits; the N cells are divided into i battery packs, where i is an integer greater than or equal to 2, and the method includes:

The main control unit confirms a battery pack with the highest average voltage and a battery pack with the lowest average voltage, and controls the battery pack with the highest average voltage to be magnetized with a wave width modulation duty ratio of more than 50 percent (50+a)%, and controls the battery pack with the highest average voltage to be magnetized with a wave width modulation duty ratio of less than 50 percent (50-a)%, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy with a wave width modulation duty ratio of more than 2a percent; and the main control unit controls the 2N switching circuits to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be less than 50 percent and (50-a)%, and controls the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be more than 50 percent and (50+a)%, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy at a bandwidth modulation duty ratio which is more than 2a percent.

7. The method for controlling active equalization of a battery according to claim 6, wherein the magnitude of a% is in direct proportion to the difference between the highest average voltage and the lowest average voltage, and the method further comprises, after the master control unit confirms the battery group with the highest average voltage and the battery group with the lowest average voltage:

the main control unit calculates the difference value between the highest value of the average voltage and the lowest value of the average voltage;

the main control unit calculates and obtains the a% according to the difference value between the highest average voltage value and the lowest average voltage value; wherein a% = (average voltage highest value-average voltage lowest value)/preset voltage equivalent, the preset voltage equivalent is used for adjusting the bandwidth modulation duty cycle;

8. The method for controlling active equalization of a battery of claim 6, further comprising:

The main control unit controls the wave width modulation duty ratio of the battery pack with the highest average voltage and the battery packs except the battery pack with the lowest average voltage to be 50% when the battery packs are magnetized, and controls the wave width modulation duty ratio of the battery pack with the highest average voltage and the battery packs except the battery packs with the lowest average voltage to be 50% when the battery packs except the battery packs with the lowest average voltage are magnetized;

the main control unit controls the preset wave width modulation duty ratio of the battery pack which does not participate in comparing the average voltage to be magnetized to be 50%, and controls the preset wave width modulation duty ratio of the battery pack which does not participate in comparing the average voltage to be magnetized to be 50%.

9. The method for controlling active equalization of a battery of claim 7, further comprising:

when the difference value between the highest average voltage value and the lowest average voltage value is smaller, the main control unit increases the adjusting frequency of the wave width modulation duty ratio so as to reduce the current of the system during active equalization and further increase the stability of the active equalization;

The main control unit calculates the adjustment percentage of the adjustment frequency of the wave width modulation duty ratio, wherein the adjustment percentage b% of the adjustment frequency of the wave width modulation duty ratio is the difference between the highest average voltage value and the lowest average voltage value divided by the voltage equivalent of the adjustment frequency of the wave width modulation duty ratio preset by the system;

10. The method for controlling active equalization of a battery of claim 6, further comprising:

The main control unit controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a first control time sequence in a control period, controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be 2a% when the battery pack with the highest average voltage is magnetized at a second control time sequence, and controls the wave width modulation duty ratio of the battery pack with the highest average voltage to be (50-a)% when the battery pack with the highest average voltage is magnetized at a third control time sequence, so as to control the battery pack with the highest average voltage to convert electric energy into magnetic energy at the wave width modulation duty ratio which is more than 2 a%; the first control timing sequence, the second control timing sequence, and the third control timing sequence of the control period are continuous;

After calculating the average voltage of each battery pack in the i battery packs, the master control unit controls the 2N switch circuits to control the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be less than 50 percent (50-a)%, controls the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be 2a percent when the battery pack with the lowest average voltage is magnetized at the second control time sequence of the control cycle, and controls the bandwidth modulation duty ratio of the battery pack with the lowest average voltage to be (50-a)%, so as to control the battery pack with the lowest average voltage to convert magnetic energy into electric energy at the bandwidth modulation duty ratio which is more than 2a percent when the battery pack with the lowest average voltage is magnetized at the third control time sequence of the control cycle;

The main control unit controls the battery pack with the highest average voltage to perform magnetism release in a fourth control time sequence in the control period until the magnetism release current is finished, and controls the battery pack with the lowest average voltage to stop magnetizing and magnetism release in the fourth control time sequence in the control period; the first control timing, the second control timing, the third control timing, and the fourth control timing of the control period are consecutive.