CN106786879B - Battery pack charging control method and charging assembly - Google Patents
Battery pack charging control method and charging assembly Download PDFInfo
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- CN106786879B CN106786879B CN201611190101.5A CN201611190101A CN106786879B CN 106786879 B CN106786879 B CN 106786879B CN 201611190101 A CN201611190101 A CN 201611190101A CN 106786879 B CN106786879 B CN 106786879B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
- H02J7/0016—Circuits for equalisation of charge between batteries using shunting, discharge or bypass circuits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
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Abstract
The invention provides a battery pack charging control method, which comprises the following steps: in the charging process of the battery pack, the voltage difference between each battery voltage or/and the battery to be balanced in the battery pack is respectively compared with the corresponding threshold voltage, and when at least one battery voltage reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, the balancing current is started to discharge the battery reaching the corresponding threshold voltage or discharge the high-voltage battery reaching the voltage difference threshold value; in the process of equalizing current discharge, the average current of charging is reduced by controlling the alternate on and off of the charging switch; or, increasing the voltage drop on the charging switch to make the charging switch work in a linear mode so as to reduce the charging current; until the battery voltage is reduced below its corresponding threshold voltage or/and the voltage difference between the batteries to be equalized is reduced to within the corresponding voltage difference threshold.
Description
Technical Field
The present invention relates to the field of battery charging technologies, and in particular, to a battery pack charging control method and a charging assembly.
Background
A battery pack is typically made up of several batteries in series. In order to prolong the service life of the battery, the battery is balanced in the charging and discharging process, so the battery charging assembly comprises a battery balancing circuit and a battery balancing switch. In order to protect the battery during charging and discharging, a charging switch M1 and a discharging switch M2 are respectively arranged in the charging assembly. The battery pack shown in fig. 1 is formed by connecting two batteries in series, a battery equalization circuit U1 samples voltages on a battery 1 and a battery 2, when the voltage of the battery 1 is higher than the voltage of the battery 2 by a certain value, the battery equalization circuit generates a control signal G1 to enable a switch K1 to be conducted so as to reduce the charging current of the battery 1, and the battery equalization circuit generates a control signal G2 to enable the switch K2 to be turned off so as to keep the charging current of the battery 2 unchanged; when the voltage of the battery 2 is higher than the voltage of the battery 1 by a certain value, the battery equalization circuit generates a control signal G1 to turn off the switch K1, the charging current of the battery 1 is kept unchanged, and the battery equalization circuit generates a control signal G2 to turn on the switch K2, so that the charging current of the battery 2 is reduced; when the voltage difference between the battery 1 and the battery 2 is within a certain value, the battery equalization circuit generates control signals G1 and G2 to turn off the switches K1 and K2, and the charging currents of the battery 1 and the battery 2 are kept unchanged.
During normal charge and discharge, both the charge switch M1 and the discharge switch M2 are turned on. When the battery equalization circuit detects that the charging process is abnormal, such as over-voltage of the battery and overcurrent of the charging current, the charging switch M1 is controlled to be turned off.
Due to the difference of internal resistances among batteries, the initial voltage is different, and in the charging and discharging processes, the equalization still cannot be achieved under certain conditions by adopting the mode. For example, in the charging process, when the charging current is relatively large, the voltage of the battery 2 is higher than the voltage of the battery 1 due to the difference between the batteries, and then the battery equalization circuit controls the switch K2 to be turned on. Even if the charging current of the battery 1 is greater than the charging current of the battery 2, the voltage of the battery 2 is still higher than the voltage of the battery 1. When the battery 2 is charged first, the battery equalization circuit controls the charge switch M1 to be turned off in order to prevent the battery 2 from being overcharged. At this time, it cannot be ensured that the voltage of the battery 1 has reached the balanced voltage of the battery 1 and the battery 2, and therefore, it cannot be ensured that the balanced state is reached.
Disclosure of Invention
The invention provides a battery pack charging control method and a charging assembly, which aim to balance a plurality of batteries in a battery pack and avoid the problem of overcharging of the batteries in the battery pack.
In order to solve the above problems, an embodiment of the present invention provides a battery pack charge control method, including the steps of:
in the charging process of the battery pack, the voltage difference between each battery voltage in the battery pack and/or the voltage difference between the batteries to be balanced is respectively compared with corresponding threshold voltages, and when at least one battery voltage reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, the balanced current is started to discharge the batteries reaching the corresponding threshold voltages or discharge the high-voltage batteries reaching the voltage difference threshold values;
in the process of equalizing current discharge, the average current of charging is reduced by controlling the alternate on and off of the charging switch; or, increasing the voltage drop on the charging switch to make the charging switch work in a linear mode so as to reduce the charging current; until the battery voltage is reduced below its corresponding threshold voltage or/and the voltage difference between the batteries to be equalized is reduced to within the corresponding voltage difference threshold.
As an embodiment, after the equalization current is generated, continuing to determine whether at least one of the cell voltages reaches its respective threshold voltage or/and whether the differential pressure between the cells to be equalized reaches a respective differential pressure threshold;
when the equilibrium current reaches its maximum current, the threshold voltage condition or/and the differential pressure condition described above is still reached;
the charging current is reduced by controlling the alternating on and off of the charging switch to reduce the average current of the charge or to increase the voltage drop across the charging switch.
As an implementation mode, in the charging process of the battery pack, detecting the state of charge of the battery pack, and adopting a constant-current charging mode when the battery pack is not full; when the battery pack is quickly full, a constant voltage charging mode is employed.
As an implementation mode, in the charging process of the battery pack, detecting the state of charge of the battery pack, and adopting a constant-current charging mode when the battery pack is not full;
when the equalizing current reaches the maximum current, wherein at least one battery voltage still reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be equalized still reaches the corresponding voltage difference threshold value, the control terminal voltage of the charging switch is regulated to enable the charging switch to work in a saturation region; and after the voltage of the battery pack and the total voltage of the voltage drop on the charging switch are raised to a preset value, the constant-current charging mode is exited, and the constant-voltage charging mode is entered, so that the voltage of the battery is reduced to be lower than the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced is reduced to be within the corresponding voltage difference threshold value.
As one embodiment, the battery pack is not full and the battery pack is full quickly is judged by whether the total voltage of the battery pack and the voltage drop of the charging switch reaches the preset value; when the total voltage is lower than the preset value, judging that the battery pack is not full; and when the total voltage reaches the preset value, judging that the battery pack is fast full.
To solve the above problems, an embodiment of the present invention provides a charging assembly, including:
the equalization circuit is coupled with the battery pack, samples the voltage of each battery in the battery pack or/and the voltage difference between the batteries to be equalized, and compares the voltage difference with corresponding threshold values respectively; when at least one battery voltage reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, starting the balance current to discharge the batteries reaching the corresponding threshold voltage or discharge the high-voltage batteries reaching the voltage difference threshold value, wherein the output end of the balance circuit is coupled with the control end of the charging switch;
and the control end of the charging switch is coupled with the equalizing circuit, and in the discharging process of the equalizing current, the charging switch is controlled to be alternately turned on and off to reduce the average charging current or increase the voltage drop on the charging switch, so that the charging switch works in a linear mode to reduce the charging current.
As one embodiment, the equalization circuit includes a logic circuit and comparators, the comparators are arranged in one-to-one correspondence with sampling signals obtained by sampling voltages of cells in the battery pack or/and a voltage difference between cells to be equalized, the comparators include a first input end, a second input end and an output end, the first input end receives the sampling signals, the second input end receives reference signals corresponding to the sampling signals and used for representing the threshold voltage or the voltage difference threshold, and the output ends of the comparators are coupled with the logic circuit, and the output ends of the logic circuit are coupled with the control end of the charge switch.
As an implementation manner, the equalization circuit comprises a pull-up circuit or a pull-down circuit, an operational amplifier and a diode, wherein the operational amplifier and the diode are respectively arranged in one-to-one correspondence with sampling signals obtained by voltage differences between various batteries in the sampling battery pack or/and batteries to be equalized, the operational amplifier comprises a first input end, a second input end and an output end, the first input end receives the sampling signals, the second input end receives reference signals which correspond to the sampling signals and are used for representing threshold voltages or voltage difference thresholds, the output end of the operational amplifier is coupled with one end of a corresponding diode, the other end of the diode is coupled with the pull-up circuit or the pull-down circuit, and the common end of the pull-up circuit or the pull-down circuit and the diode is coupled with the control end of the charging switch.
As an embodiment, the sampling signal is a voltage controlled voltage source controlled by and used to characterize the respective battery voltage or differential pressure.
As an implementation manner, the operational amplifier judges whether at least one battery voltage reaches a corresponding threshold voltage or/and a voltage difference between batteries to be balanced reaches a corresponding voltage difference threshold value, and if the judgment that the threshold voltage condition or/and the voltage difference condition is reached, the corresponding diode is conducted, so that the voltage of the control end of the charging switch is changed, and the charging switch works in a linear mode to reduce the charging current.
Drawings
FIG. 1 is a circuit diagram of a prior art charging circuit;
FIG. 2 is a block diagram of a third embodiment of a charging assembly of the present invention;
FIG. 3 is a block diagram of a fourth embodiment of a charging assembly of the present invention;
fig. 4 is a block diagram of a fifth embodiment of the charging assembly of the present invention.
Detailed Description
The foregoing and other features and advantages of the invention will be apparent from the following, more particular, description of the invention, as illustrated in the accompanying drawings, in which embodiments described are merely some, but not all embodiments of the invention.
The particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples in embodiments of the invention. It will be appreciated by those of ordinary skill in the art that the drawings provided herein are for illustrative purposes and that the drawings are not necessarily drawn to scale. It will be understood that when an element is referred to as being "coupled to" or "connected to" another element, it can be directly coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly coupled to" or "directly connected to" another element, there are no intervening elements present. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. A battery pack charge control method comprising the steps of:
s100: in the charging process of the battery pack, the voltage difference between each battery voltage in the battery pack and/or the voltage difference between the batteries to be balanced is respectively compared with corresponding threshold voltages, and when at least one battery voltage reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, the balanced current is started to discharge the batteries reaching the corresponding threshold voltages or discharge the high-voltage batteries reaching the voltage difference threshold values;
s101: during the discharging process of the equalization current, the charging switch is operated in a linear mode by controlling the alternating on and off of the charging switch to reduce the average current of charging or increasing the voltage drop across the charging switch until the battery voltage is reduced below its corresponding threshold voltage or/and the voltage difference between the batteries to be equalized is reduced to within the corresponding voltage difference threshold.
In the charging process of the battery pack, detecting the state of charge of the battery pack, and when the battery pack is not fully charged, adopting a constant-current charging mode when the voltage of the battery pack is low; when the battery pack is charged quickly, the battery pack voltage is high, and then a constant voltage charging mode is adopted. Judging whether the battery pack is not full and whether the battery pack is full quickly is judged by whether the total voltage of the voltage drops on the battery pack voltage, the charging switch and the discharging switch reaches a preset value or not; if the total voltage is lower than the preset value, judging that the battery pack is not full; and if the total voltage reaches the preset value, judging that the battery pack is fast full.
Wherein the threshold voltage and the differential pressure threshold may be constant or different values for different batteries. The charge switch control and the equalization current release of the method are performed simultaneously, namely, the charge switch control can be performed when the maximum value of the equalization current is not reached yet.
The conditions for opening the equalization current are three: firstly, at least one battery voltage in the battery pack reaches a corresponding threshold voltage; secondly, the pressure difference between the batteries to be balanced reaches a corresponding pressure difference threshold value; thirdly, the first condition and the second condition are met at the same time, and any one of the three conditions can be met. There are two ways of equalizing the current discharge process: firstly, alternately switching on and switching off a charging switch; and secondly, the voltage drop on the charging switch is increased, so that the battery pack works in a linear mode, and the balance of a plurality of batteries in the battery pack can be realized in the two modes.
According to different conditions, any one of the two modes is selected, and a result corresponding to the conditions is obtained, so that the battery equalization can be realized. When at least one battery voltage in the battery pack reaches the corresponding threshold voltage, the battery voltage is reduced to be lower than the corresponding threshold voltage, and then the battery balance can be realized; when the pressure difference between the batteries to be balanced reaches a corresponding pressure difference threshold value, the pressure difference between the batteries to be balanced is reduced to be within the corresponding pressure difference threshold value, and then the balance of the batteries can be realized; when at least one cell voltage in the battery pack reaches its corresponding threshold voltage and the voltage difference between the cells to be equalized reaches the corresponding voltage difference threshold value, then the cell voltage must be reduced below its corresponding threshold voltage and the voltage difference between the cells to be equalized is reduced to within the corresponding voltage difference threshold value at the same time.
Although the conditions for opening the equalization current are different, the technical solution and principle for solving the problem are substantially the same, and the battery voltage and the corresponding threshold voltage are described in the following several embodiments when the battery charging control method of the present invention is further described.
It should be noted that: the equalization current is different from the discharge current passing through the discharge switch, and the discharge switch is a switch for performing discharge control when the battery pack supplies power to the outside, so that the discharge current of the discharge switch is not directly related to the solution of the technical problem of the present invention, and the discharge switch is in a fully-conductive state in the charging process, so that the description is given herein.
Example 1
A battery pack charge control method comprising the steps of:
s200: in the charging process of the battery pack, each battery voltage in the battery pack is respectively compared with a corresponding threshold voltage, and when at least one battery voltage reaches the corresponding threshold voltage, the balanced current is started to discharge the battery reaching the corresponding threshold voltage;
s201: after the equalization current is generated, whether at least one battery voltage reaches the corresponding threshold voltage is continuously judged, when the equalization current reaches the maximum current, the threshold voltage condition is still reached, and the average charging current is reduced by controlling the alternate on and off of the charging switch until the battery voltage is reduced to be lower than the corresponding threshold voltage.
In this embodiment, when the threshold voltage condition (but may also satisfy the differential pressure threshold condition or satisfy both conditions, hereinafter, if the same descriptions are all presented, it means that any one of the threshold voltage condition and the differential pressure threshold condition is satisfied and both conditions are satisfied at the same time), the equalization current is turned on to perform discharging, but at this time, the charge switch is not controlled, and only when the equalization current reaches the maximum current and the battery voltage still satisfies the threshold voltage condition (i.e., whether at least one battery voltage in the battery pack reaches its corresponding threshold voltage) is the equalization current controlled to make the battery balanced.
Example two
A battery pack charge control method comprising the steps of:
s300: in the charging process of the battery pack, each battery voltage in the battery pack is respectively compared with a corresponding threshold voltage, and when at least one battery voltage reaches the corresponding threshold voltage, the balanced current is started to discharge the battery reaching the corresponding threshold voltage;
s301: during the discharging of the balancing current, the charging switch is operated in linear mode by increasing the voltage drop across it until the battery voltage is reduced below its corresponding threshold voltage.
In the charging process of the battery pack, the state of charge of the battery pack is detected in real time, and when the battery pack is not fully charged, a constant-current charging mode is adopted. When the balanced current reaches the maximum current, the threshold voltage condition is still reached, and the control terminal voltage of the charging switch is regulated to enable the charging switch to work in a saturation region. When the voltage of the battery pack (the sum of the voltages of each battery in the battery pack), the total voltage of the voltage drops on the charging switch and the discharging switch are raised to a preset value, the constant-current charging mode is exited, and the constant-voltage charging mode is entered, so that the voltage of the battery is reduced to be lower than the corresponding threshold voltage.
A charging assembly includes an equalization circuit and a charging switch.
The equalization circuit is coupled with the battery pack, samples the voltage difference between each battery voltage or/and the battery to be equalized in the battery pack, and respectively compares the voltage difference with corresponding threshold values (when the battery voltage is sampled, the battery voltage is compared with the corresponding voltage threshold value; when at least one battery voltage reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, starting the balance current to discharge the batteries reaching the corresponding threshold voltage or discharge the high-voltage batteries reaching the voltage difference threshold value, wherein the output end of the balance circuit is coupled with the control end of the charging switch;
and the control end of the charging switch is coupled with the equalizing circuit, and in the discharging process of the equalizing current, the charging switch is controlled to be alternately turned on and off to reduce the average charging current or increase the voltage drop on the charging switch, so that the charging switch works in a linear mode to reduce the charging current.
The sampling signals are voltage signals of voltage controlled voltage sources controlled by respective battery voltages or voltage differentials and used to characterize the respective battery voltages or/and voltage differentials, and the sampling signals in the following embodiments are all described in terms of battery voltages.
The conditions for controlling the charge switch are three: firstly, at least one battery voltage in the battery pack reaches a corresponding threshold voltage; secondly, the pressure difference between the batteries to be balanced reaches a corresponding pressure difference threshold value; thirdly, the first condition and the second condition are met at the same time, and any one of the three conditions can be met. The working modes of the charging switch are two types: firstly, the equalizing circuit controls the alternate on and off of the charging switch; and secondly, the voltage drop on the charging switch is increased through an equalizing circuit, so that the battery pack works in a linear mode, and the equalizing of a plurality of batteries in the battery pack can be realized in the two modes.
According to different conditions, any one of the two modes is selected, and a result corresponding to the conditions is obtained, so that the battery equalization can be realized. When at least one battery voltage in the battery pack reaches the corresponding threshold voltage, the battery voltage is reduced to be lower than the corresponding threshold voltage, and then the battery balance can be realized; when the pressure difference between the batteries to be balanced reaches a corresponding pressure difference threshold value, the pressure difference between the batteries to be balanced is reduced to be within the corresponding pressure difference threshold value, and then the balance of the batteries can be realized; when at least one cell voltage in the battery pack reaches its corresponding threshold voltage and the voltage difference between the cells to be equalized reaches the corresponding voltage difference threshold value, then the cell voltage must be reduced below its corresponding threshold voltage and the voltage difference between the cells to be equalized is reduced to within the corresponding voltage difference threshold value at the same time.
Although the conditions for opening and controlling the charging switch are different, the technical scheme and principle for solving the problem are approximately the same, and when the battery pack charging control method of the invention is further described in the following embodiments, the battery voltage and the corresponding threshold voltage are used for description; the charge switch is exemplified by an NMOS.
Implementation three
As shown in fig. 2, the equalizing circuit includes a logic circuit and comparators, the number of comparators is set in one-to-one correspondence with the number of sampling signals. The comparators comprise a first input end, a second input end and an output end, wherein the first input end receives a sampling signal, the second input end receives a reference signal corresponding to the sampling signal, the output ends of the comparators are coupled with the logic circuit, and the output ends of the logic circuit are coupled with the control end of the charging switch.
The voltage on each voltage-controlled voltage source is determined by the corresponding battery, i.e., the voltage on voltage-controlled voltage source U11 is k×v1, where V1 is the voltage on battery 1, the voltage on voltage-controlled voltage source U1N is k×vn, where VN is the voltage on battery N. The output of the voltage-controlled voltage source is connected to one input of the corresponding comparator, the other input of the comparator is connected to the reference signal VREF1, the output of each comparator is connected to the logic circuit U20, and the logic circuit U20 controls the gate voltage of the charge switch M1. If the charge switch M1 is a PMOS, the output of the logic circuit U20 is opposite to that of the present embodiment. The voltage-controlled voltage source is connected to the negative input end of the comparator, the reference signal is connected to the positive input end of the comparator, for example, when the outputs of all comparators are high, the output G4 of the logic circuit U20 is high (if the charging switch M1 is PMOS, the G4 is low), and the charging switch M1 is turned on; when the output of one comparator is low, the output G4 of the logic circuit U20 is low (G4 is high if the charge switch M1 is PMOS), and the logic circuit U20 controls the charge switch M1 to remain off for 1 second. After 1 second, the output G4 of the logic circuit U20 is high and the charge switch M1 is turned on. After conducting for a certain time, when the output of one of the comparators is low, the output G4 of the logic circuit U20 is low and remains for 1 second, and so on.
Example IV
As shown in fig. 3, the equalizing circuit includes an output adjusting circuit, an operational amplifier, and diodes, the number of which is set in one-to-one correspondence with the number of sampling signals. The operational amplifier comprises a first input end, a second input end and an output end, wherein the first input end receives a sampling signal, the second input end receives a reference signal corresponding to the sampling signal, the output end is coupled with one end of a diode corresponding to the operational amplifier, the other end of the diode is coupled with an output adjusting circuit, and the common end of the output adjusting circuit and the diode is coupled with a control end of the charging switch. The output adjusting circuit is used for increasing the voltage drop on the charging switch, and can be a pull-up circuit or a pull-down circuit, mainly depending on the type of the charging switch, and in this embodiment, the charging switch M1 is an NMOS, so the output adjusting circuit is a pull-up circuit.
The operational amplifier judges whether the voltage of at least one battery reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, and if the voltage of at least one battery reaches the threshold voltage condition or/and the voltage difference condition, the corresponding diode is conducted, so that the voltage of the control end of the charging switch is changed, and the charging switch works in a linear mode to reduce the charging current.
The voltage on each voltage-controlled voltage source is determined by the corresponding battery, that is, the voltage on the voltage-controlled voltage source U11 is k×v1, where V1 is the voltage on the battery 1, the voltage on the voltage-controlled voltage source U1N is k×vn, where VN is the voltage on the battery N, and the voltage of the voltage-controlled voltage source is the sampled battery voltage, which is also the sampling signal described above. The difference from the third embodiment is that the output of the voltage controlled voltage source is connected to an operational amplifier instead of a comparator. The output of the voltage-controlled voltage source is connected to one input of a corresponding operational amplifier, the other input of the operational amplifier is connected to the reference signal VREF1, the outputs of the plurality of operational amplifiers are connected to the control electrode G4 of the charge switch M1 through respective diodes, wherein the anodes of all the diodes are connected together and connected to the control electrode G4 of the charge switch M1, and the cathodes of the respective diodes are connected to the output of the corresponding operational amplifier. The pull-up circuit is connected to the control electrode G4 of the charge switch M1. Taking the case that the voltage-controlled voltage source is connected to the negative end of the operational amplifier and the reference signal is connected to the positive end of the operational amplifier, when the output of all the operational amplifiers is high, G4 is pulled up by the pull-up circuit, and the charging switch M1 is turned on; when the voltage of a voltage-controlled voltage source is greater than the reference signal VREF1, the output of the corresponding operational amplifier is reduced, the corresponding diode is conducted, the control electrode G4 of the charging switch is pulled down, so that the on-resistance of the charging switch M1 is increased, the voltage drop on the charging switch M1 is increased, when the charging current is small to the current of single-section discharging, the voltage of the corresponding battery is not continuously increased, and other batteries are in a state of continuous charging, therefore, the battery balance can be realized through the embodiment. If the charge switch M1 is a PMOS, the output adjusting circuit becomes a pull-down circuit, the voltage-controlled voltage source is connected to the positive input terminal of the operational amplifier, the reference voltage is connected to the negative input terminal of the operational amplifier, the anode of the diode is connected to the output terminal of the corresponding operational amplifier, and the cathode is connected to the control electrode of the charge switch M1. When the output of all operational amplifiers is low, G4 is pulled down by the pull-down circuit, and the charging switch M1 is turned on; when the voltage of a voltage-controlled voltage source is larger than the reference signal VREF1, the output of the corresponding operational amplifier is raised, the corresponding diode is conducted, the control electrode G4 of the charging switch is pulled up, so that the on-resistance of the charging switch M1 is increased, the voltage drop on the charging switch M1 is increased, when the charging current is small to the current of single-section discharging, the voltage of the corresponding battery cannot be continuously raised, and other batteries are in a state of continuous charging.
Example five
As shown in fig. 4, the modification is made on the basis of the third embodiment shown in fig. 2. Since fig. 2 illustrates only sampling the voltage of a single cell and comparing with the corresponding cell threshold voltage. In the embodiment shown in fig. 4, the sampling of the differential pressure of the cells to be balanced is increased, where the differential pressure of the cells to be balanced may be the differential pressure between the single cells or the differential pressure between the battery packs, for example, the differential pressure generated by comparing the differential pressure of two cells with the differential pressure of two other cells. Furthermore, sampling of the differential pressure of the battery to be equalized is also applicable to the fourth embodiment, that is, the differential pressure sampling section may be applicable to the respective embodiments.
For convenience of description, only the added portions are specifically described. Meanwhile, the logic circuit 1 and the logic circuit 2 are respectively arranged in the embodiment, and it is to be noted that the technical problem of the invention can be solved by connecting the output end of the comparator of the single battery sampling part and the output end of the comparator of the differential pressure sampling part of the battery to be balanced with the same equalization circuit. However, by separately providing two logic circuits, the technical problem of the present invention can be solved more preferably, and the function of adopting one logic circuit can be realized, or the control can be performed separately, for example, the threshold condition of a single battery and the priority of the differential pressure condition of the battery to be balanced are determined.
Specifically, the voltage across the voltage-controlled voltage sources U31 to U3n is determined by the voltage difference of the corresponding cells to be equalized, i.e., the voltage across the voltage-controlled voltage source U31 is k×v1-V2, where V1 is the voltage across the cell 1 and V2 is the voltage across the cell 1, and the voltage-controlled voltage source U31 is used to characterize the voltage difference of V1-V2, which is compared with the corresponding reference signal VREF2 by the comparator U41. Since there is a case where V1 is higher than V2, and possibly a case where V2 is higher than V1, a voltage-controlled voltage source U32 for characterizing a voltage difference of voltage V2-V1, on which a voltage of K x (V2-V1) is provided, is compared with the corresponding reference signal VREF2 by a comparator U42. The voltage on voltage controlled voltage source U3N is K (VN-V (N-1)), where VN is the voltage on battery N and V (N-1) is the voltage on battery N-1. For the selection of the voltages of the batteries to be balanced, the difference comparison between any two batteries can be adopted, or the comparison can be carried out only on part of the batteries according to the actual conditions and requirements. Thus, N in voltage controlled voltage source U3N and comparator U4N represent different numbers than N in VN to illustrate the distinction. The output of the voltage-controlled voltage source is connected to one input of the corresponding comparator, the other input of the comparator is connected to the reference signal VREF2, the output of each comparator is connected to the logic circuit U40, and the logic circuit U40 controls the gate voltage of the charge switch M1. If the charge switch M1 is a PMOS, the output of the logic circuit U40 is opposite to that of the present embodiment.
Meanwhile, the pressure difference between the batteries to be balanced can be optimized, namely, the battery with the minimum voltage in all the batteries is selected, and other batteries are respectively compared with the battery with the minimum voltage so as to generate corresponding pressure difference, so that the sampling and comparison times can be reduced. In this case the number of the elements to be formed is,
compared with the prior art, the invention has the beneficial effects that: in the charging process of the battery pack, the battery equalization circuit controls the charge switch M1 to be turned on and off so as to reduce the equivalent charge current and equalize the battery cells; in the charging process of the battery pack, when the batteries are required to be balanced, a battery balancing circuit controls a charging switch M1 to be a linear switch so as to reduce charging current; the charging switch M1 controlled by the battery equalization circuit not only serves as a protection switch to prevent the battery from overshooting during charging, but also has the function of battery equalization.
The foregoing embodiments have been provided for the purpose of illustrating the general principles of the present invention, and are not to be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art without departing from the spirit and principles of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. A battery pack charge control method, comprising the steps of:
in the charging process of the battery pack, the voltage difference between each battery voltage or/and the battery to be balanced in the battery pack is respectively compared with the corresponding threshold voltage, and when at least one battery voltage reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, the balancing current is started to discharge the battery reaching the corresponding threshold voltage or discharge the high-voltage battery reaching the voltage difference threshold value;
after the equalization current is generated, continuing to judge whether at least one battery voltage reaches the corresponding threshold voltage or/and whether the voltage difference between the batteries to be equalized reaches the corresponding voltage difference threshold value;
when the equilibrium current reaches its maximum current, the threshold voltage condition or/and the differential pressure condition described above is still reached,
in the process of equalizing current discharge, the average charging current is reduced by controlling the alternate on and off of the charging switch; or, increasing the voltage drop on the charging switch to make the charging switch work in a linear mode so as to reduce the charging current; until the battery voltage is reduced below its corresponding threshold voltage or/and the voltage difference between the batteries to be equalized is reduced to within the corresponding voltage difference threshold.
2. The battery pack charge control method according to claim 1, wherein: in the charging process of the battery pack, detecting the state of charge of the battery pack, and adopting a constant-current charging mode when the battery pack is not full; when the battery pack is quickly full, a constant voltage charging mode is employed.
3. The battery pack charge control method according to claim 1, wherein: in the charging process of the battery pack, detecting the state of charge of the battery pack, and adopting a constant-current charging mode when the battery pack is not full;
when the equalizing current reaches the maximum current, and at least one battery voltage still reaches the corresponding threshold voltage or/and the pressure difference between the batteries to be equalized still reaches the corresponding pressure difference threshold value, the control terminal voltage of the charging switch is regulated to enable the charging switch to work in a saturation region; and after the total voltage of the voltage drops on the battery pack voltage, the charging switch and the discharging switch is increased to a preset value, the constant-current charging mode is exited, and the constant-voltage charging mode is entered, so that the battery voltage is reduced to be lower than the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced is reduced to be within the corresponding voltage difference threshold value.
4. The battery pack charge control method according to claim 3, wherein: the states of the battery pack which is not full and the battery pack which is fast full are judged by whether the total voltage of the voltage drops on the battery pack voltage, the charging switch and the discharging switch reaches the preset value or not; when the total voltage is lower than the preset value, judging that the battery pack is not full; and when the total voltage reaches the preset value, judging that the battery pack is fast full.
5. A charging assembly, characterized in that: comprising the steps of (a) a step of,
the equalization circuit is coupled with the battery pack, samples the voltage of each battery in the battery pack or/and the pressure difference between the batteries to be equalized, and compares the voltage with corresponding threshold values respectively; when at least one battery voltage reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, starting the balance current to discharge the batteries reaching the corresponding threshold voltage or discharge the high-voltage batteries reaching the voltage difference threshold value, wherein the output end of the balance circuit is coupled with the control end of the charging switch;
and the control end of the charging switch is coupled with the equalizing circuit, and when the equalizing current reaches the maximum current, the threshold voltage condition or/and the differential pressure condition are still reached, and the charging switch is controlled to be alternately turned on and off to reduce the average charging current or increase the voltage drop on the charging switch, so that the charging switch works in a linear mode to reduce the charging current.
6. The charging assembly of claim 5, wherein: the equalization circuit comprises a logic circuit and comparators, wherein the comparators are arranged in one-to-one correspondence with sampling signals obtained by sampling the voltage of each battery in the battery pack or/and the voltage difference between the batteries to be equalized, the comparators comprise a first input end, a second input end and an output end, the first input end receives the sampling signals, the second input end receives reference signals which correspond to the sampling signals and are used for representing the threshold voltage or the voltage difference threshold value, the output ends of the comparators are coupled with the logic circuit, and the output ends of the logic circuit are coupled with the control end of the charging switch.
7. The charging assembly of claim 5, wherein: the equalization circuit comprises a pull-up circuit or a pull-down circuit, an operational amplifier and a diode, wherein the operational amplifier and the diode are respectively arranged in one-to-one correspondence with sampling signals obtained by voltage differences between various batteries in the sampling battery pack or/and batteries to be equalized, the operational amplifier comprises a first input end, a second input end and an output end, the first input end receives the sampling signals, the second input end receives reference signals which correspond to the sampling signals and are used for representing threshold voltages or voltage difference thresholds, the output end of the operational amplifier is coupled with one end of a corresponding diode, the other end of the diode is coupled with the pull-up circuit or the pull-down circuit, and the common end of the pull-up circuit or the pull-down circuit and the diode is coupled with the control end of the charge switch.
8. The charging assembly of claim 6 or 7, wherein: the voltage difference between the batteries to be balanced is the voltage difference of each battery compared with the battery with the lowest voltage.
9. The charging assembly of claim 6 or 7, wherein: the sampling signal is a voltage-controlled voltage source controlled by and used for representing the corresponding battery voltage or differential pressure.
10. The charging assembly of claim 7, wherein: the operational amplifier judges whether the voltage of at least one battery reaches the corresponding threshold voltage or/and the voltage difference between the batteries to be balanced reaches the corresponding voltage difference threshold value, and if the voltage of at least one battery reaches the threshold voltage condition or/and the voltage difference condition, the corresponding diode is conducted, so that the voltage of the control end of the charging switch is changed, and the charging switch works in a linear mode to reduce the charging current.
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| CN108377019A (en) * | 2018-04-08 | 2018-08-07 | 上海航天计算机技术研究所 | Spaceborne lithium battery balance control method and system |
| CN109037814B (en) * | 2018-09-05 | 2021-02-19 | 成都芯源系统有限公司 | Charge balance management circuit and method |
| KR102659679B1 (en) * | 2019-04-22 | 2024-04-19 | 주식회사 엘지에너지솔루션 | Apparatus and method for determining differential voltage curve of battery, and battery pack including the apparatus |
| CN112937366B (en) * | 2019-12-10 | 2023-09-08 | 北汽福田汽车股份有限公司 | Battery charging method and device and vehicle |
| CN114050554B (en) * | 2022-01-11 | 2022-05-13 | 深圳市创芯微微电子有限公司 | Battery protection circuit and power tube control method thereof |
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| CN206364542U (en) * | 2016-12-21 | 2017-07-28 | 杰华特微电子（杭州）有限公司 | A kind of charging assembly |
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| JP3681624B2 (en) * | 2000-08-31 | 2005-08-10 | 富士通株式会社 | Charging circuit, charging / discharging circuit, and battery pack |
| US7081737B2 (en) * | 2003-06-19 | 2006-07-25 | O2Micro International Limited | Battery cell monitoring and balancing circuit |
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| CN101667741A (en) * | 2008-09-02 | 2010-03-10 | 凹凸电子（武汉）有限公司 | Charging circuit, charging current path and battery charging system |
| CN201584799U (en) * | 2009-11-18 | 2010-09-15 | 徐成宪 | Equalizing charge system for rechargeable battery |
| CN206364542U (en) * | 2016-12-21 | 2017-07-28 | 杰华特微电子（杭州）有限公司 | A kind of charging assembly |
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