TWI593212B - Smart battery quick balancer - Google Patents

Description

Smart fast battery balancer

The present invention relates to an intelligent fast battery balancer, and more particularly to an intelligent fast battery balancer that can quickly achieve voltage balance between a plurality of battery cells of a battery pack.

In recent years, due to the global warming impact and energy crisis, the importance of electric vehicle applications and renewable energy systems has gradually increased. For renewable energy systems such as wind power and solar power generation, due to natural conditions, it is impossible to supply stable at any time. Energy, therefore, must rely on secondary batteries to store and release energy, while for pure electric vehicles that replace fuel with electrical energy, secondary batteries must be relied upon to provide power.

Lithium batteries usually use batteries in series to form a battery pack in response to high power and high voltage requirements, but batteries connected in series to a battery pack may have different characteristics due to differences in production process and ambient temperature. The internal resistance, power and voltage of each battery are inconsistent when used. The inconsistency of the battery power in series causes the battery pack to reduce the power utilization rate during charging and discharging, and also shortens the battery life. Therefore, battery balancers in battery management systems have received increasing attention.

The type of battery balancer can be divided into passive and active balance according to the energy balance mechanism used. Passive balance, although simple in structure and easy to control, is balanced by consuming battery energy, so the balance efficiency is poor. Active balancing is to achieve battery balance by transferring energy between batteries. Although the cost of active balancing method and circuit are difficult to achieve, the balance speed and efficiency are better than passive, so it has gradually become the mainstream.

However, the traditional active battery balancer architecture can only transfer power between adjacent batteries, and its balance current will decrease as the battery pressure difference becomes smaller in the later stage of battery balance, resulting in a relatively slow balance speed. The balancing current is mainly affected by the duty cycle of the switch, the battery voltage and the battery voltage. If the fixed main switch conduction period is maintained during the balancing process, the balancing current will decrease due to the change of the battery voltage. In order to solve this problem, it is proposed in the literature to adjust the duty cycle mode according to the battery voltage change to maintain the balance current. However, because of the battery nonlinearity and the undesired characteristics of the circuit, the performance of simply adjusting the balance current based on the mathematical formula is still improved. space.

The active balancer can be subdivided into four energy transfer modes: battery transfer to battery, battery transfer to battery pack, battery pack transfer to battery, battery transfer to battery pack, and battery transfer. These energy transfer methods can be implemented with different circuit architectures: the main classification is capacitive, inductive and transformer isolation. The capacitive balancing circuit proposed by the prior art mainly uses switch switching to achieve charge transfer between cells. Although the structure is simple and the control is easy, due to the limitation of the battery series structure and the balance, the current will decrease as the voltage difference becomes smaller, resulting in a relatively slower balancing speed. Another literature proposes an inductive balancing circuit based on a step-down circuit. Because it can control the balance current, it can overcome the problem of lower balance current drop, but this method will also be affected by the battery serial structure, so that the battery can only be transmitted between adjacent batteries. In addition, the prior art also proposes a transformer isolation type balance circuit, which is mainly based on a flyback circuit, and has transformer isolation, in addition to balancing between any battery, it is also possible to perform multiple batteries in the same cycle. Balance the action. In addition, according to the operating principle of the flyback circuit, the balance current and operation mode are controlled to improve the balance efficiency. In the prior art, the balanced circuit based on the transformer isolation type can be mainly divided into two types of structures: a multi-transformer and a multi-rewinder. Both of these architectures can perform battery-to-battery and battery-to-battery power transmission, but on multi-winding transformers. In terms of architecture, if the balance of the number of batteries is changed, the windings need to be re-wound, so modularization is not easy. It has also been suggested in the literature that if the secondary side of the multi-transformer type is realized by synchronous rectification, the circuit can simultaneously have the battery balancing function of the battery pack and the battery pack, and increase the control flexibility. In the previous balancing technique, the balancing current is mainly affected by the duty cycle of the switch, the battery voltage and the battery voltage. If the main switch on-time is maintained during the balancing process, the balancing current is reduced due to the change of the battery voltage. In order to solve this problem, another paper proposes to adjust the duty cycle mode according to the battery voltage change to maintain the balance current. However, due to the non-linear characteristics of the battery and the undesired characteristics of the circuit, there is still room for improvement in the performance of simply adjusting the balance current according to the mathematical formula. .

Although there are various battery balancing methods as described above, there is still a need in the art for a novel intelligent fast battery balancer to improve the balance efficiency between batteries.

The main object of the present invention is to provide a modular bidirectional flyback balancing circuit capable of bidirectional energy transmission between a battery pack and its battery cells, which has a smart balance current control function, which does not require precise mathematics. In the case of the model, the voltage balance between the battery cells of the battery pack is quickly reached.

To achieve the above object, a smart fast battery balancer is proposed which has:

At least one bidirectional flyback circuit, each of the bidirectional flyback circuits has a first connection port, a first control end, a second connection port, and a second control end, each of the bidirectional flyback circuits Each of the first ports is electrically coupled to a battery unit of a battery pack, and the second ports of each of the two-way flyback circuits are electrically coupled to the battery pack. And the first control end of each of the bidirectional flyback circuits is configured to receive a first switching signal, and each of the second control ends of each of the bidirectional flyback circuits is configured to receive a first Switching the signal so that the battery pack charges any of the battery cells or causes any of the battery cells to charge the battery pack;

At least one first analog-to-digital circuit, each for converting an analog voltage of the battery unit into a first digital signal;

a second analog-to-digital circuit for converting an analog voltage of the battery pack into a second digit signal;

a control unit, configured to perform a power transmission process between the battery pack and each of the battery cells according to the second digit signal and each of the first digit signals to each of the batteries in the battery pack A voltage balance is achieved between the units, wherein the power transmission program includes a conduction period fuzzy operation to determine the first switching signal and the second switching signal according to the second digital signal and a first digital signal a responsibility cycle, the responsibility cycle fuzzy operation comprises inferring according to a rule base by using a minimum inference engine, and the rule library divides the second digit signal and a first digit signal into a plurality of values The level is a plurality of numerical levels corresponding to the duty cycle.

In an embodiment, the bidirectional flyback circuit includes a transformer and two power switches.

In an embodiment, the controller unit includes a microcontroller.

In an embodiment, the duty cycle fuzzy operation comprises performing a defuzzification operation using a weighted average method.

In one embodiment, the smart fast battery balancer further includes a LabVIEW human machine interface to monitor the power transfer program.

The detailed description of the drawings and the preferred embodiments are set forth in the accompanying drawings.

Please refer to FIG. 1, which is a block diagram showing an embodiment of the smart fast battery balancer of the present invention. As shown in FIG. 1, the smart fast battery balancer has at least one bidirectional flyback circuit 100, at least one first analog-to-digital circuit 110, a second analog-to-digital circuit 120, and a control unit 130.

Each of the bidirectional flyback circuits 100 has a first port C1, a first control terminal A, a second port C2, and a second control terminal B. Each of the bidirectional flyback circuits 100 The first port C1 is electrically coupled to one of the battery cells 200 of the battery pack 300, and the second port C2 of each of the bidirectional flyback circuits 100 is used with the battery pack. The first control terminal A of each of the bidirectional flyback circuits 100 is configured to receive a first switching signal S _AI , I between 1 and N, and each of the two directions The second control terminal B of the flyback circuit 100 is configured to receive a second switching signal S _BI , 1 between 1 and N, so that the battery pack 300 is paired with any of the battery cells 200. Charging or causing any of the battery cells 200 to charge 300 the battery pack. In addition, the bidirectional flyback circuit can include a transformer and two power switches to achieve bidirectional energy transfer.

Each of the first analog-to-digital circuits 110 is configured to convert the analog voltage V _{BI of} a battery cell 200 into a first digital signal D _1,BI , I between 1 and N.

The second analog-to-digital circuit 120 is configured to convert the analog voltage V _{BM of} the battery pack 300 into a second digital signal D ₂ .

The control unit 130 may include a microcontroller for the battery between the second digital signal D ₂ and each of the first digital signals D _{1, BI} , I between 1 and N. And performing a power transfer procedure between each of the battery cells 200 to achieve voltage balance between each of the battery cells 200 of the battery pack 300, wherein the power transfer program includes a turn-on period fuzzy operation to Determining the second digital signal D ₂ and the first digital signal D _1,BI , I between 1 and N, determining one of the first switching signal S _AI and the second switching signal S _BI a period, I is between 1 and N, the responsibility period fuzzy operation comprises inferring according to a rule base by using a minimum inference engine, and the rule library is to use the second digit signal D ₂ and the first The digit signals D _{1, BI are} each divided into a plurality of numerical levels to correspond to a plurality of numerical levels of the duty cycle. In addition, the duty cycle fuzzy operation may also include performing a defuzzification operation using a weighted average method.

In addition, the smart fast battery balancer may further include a LabVIEW human machine interface to monitor the power transmission program.

The circuit and operation principle of the present invention will be described in detail below:

Circuit hardware architecture and operational analysis:

Since the present invention is intended to transfer energy between a single battery and a battery pack, and the balance circuit between the two needs to have an isolation function, a flyback architecture with a small number of components and a low cost is selected as the power circuit of the balancer. In order to make the balancer control more flexible, a two-way flyback balancing circuit that can transfer energy in both directions is used.

Bidirectional flyback converter balancing circuit:

When the diode on the secondary side of the flyback circuit is replaced with an active switch, it becomes a bidirectional flyback converter circuit. As shown in FIG. 2, the battery can transfer energy from the primary side to the secondary side battery pack, or can transfer energy from the secondary side battery pack to the primary side battery, and has the battery to the battery pack and the battery pack to the battery. Two-way balance ability. Adding multiple sets of bidirectional flyback circuits plus a microprocessor and control strategy is the balancing circuit proposed by the present invention. The following describes the operation mode of the circuit for balancing battery energy.

Battery-to-battery energy transfer mode:

When the battery level is high, this mode of operation into the balancer, when the main switch turn on Q ₁ when Q ₂ is turned off, the equivalent circuit shown in Figure 3a, the energy storage battery to the primary side of the magnetizing inductance L _m; and when when Q ₁ Q ₂ is turned off, the equivalent circuit shown in Figure 3b, then the magnetizing inductance discharging, transferring the energy to the secondary side of the battery pack, charging the entire battery pack.

Battery pack to battery energy transmission mode:

If the battery is low, the balancer needs to enter this mode. When Q _{2 is} turned on, Q _{1 is} turned off. The equivalent circuit is shown in Figure 4a. The battery pack discharges to the secondary side magnetizing inductance L _m2 for energy storage. When Q ₂ off turn on Q _1, the equivalent circuit shown in Figure 4b, at this time the secondary side of the excitation inductance discharging, transferring the energy to the secondary side of a single battery charge.

The actual balance circuit operation mode:

The balanced operation concept proposed by the present invention is as shown in FIG. 5, and the left end is a single battery. If some batteries are detected to have a high power, the battery-to-battery balance mode is performed through the bidirectional flyback circuit, and discharged to the battery pack; Conversely, if the battery power is low, the battery pack balances the battery, and the battery pack discharges to charge a single battery. The voltage of each battery and battery pack is provided to the microcontroller through the analog-to-digital circuit, and a balance command is issued to each group of bidirectional flyback circuits to achieve battery balancing.

Balance current relationship:

Since the actual circuit operation of the flyback converter architecture includes non-ideal characteristics, the balance current cannot be accurately adjusted mathematically. Therefore, the present invention adds fuzzy control to adjust the current of the balance circuit, thereby accelerating the balance speed. The ideal battery balancer should have the advantages of short balance time, high efficiency and safety protection. Therefore, under the premise of safe use of the battery, raising the balance speed is the main demand, and in order to improve the balance speed, the balance current must be adjusted immediately. According to the balancer architecture proposed by the present invention, if the balance mode is that the battery transfers energy to the battery pack, V _B is the battery voltage, and V _PACK is the battery pack voltage, and the bidirectional flyback converter architecture according to FIG. 2 can derive the balance. Current relationship is as follows

(1)

Where I _B is the battery current, I _PACK is the battery current, D ₁ is the Q ₁ duty cycle, R is the battery pack equivalent resistance, N ₁ , N ₂ is the first, and the secondary winding turns. (1) can be obtained after finishing

(2)

Conversely, if the balance mode is to transfer energy to the battery pack, the equilibrium current relationship can be derived as shown in (3). The relationship between the inductor current and the output current is shown in (4), which can be expressed as

(3)

(4)

It can be seen from the above relationship that when the battery parameter is determined after the hardware parameter is determined, the balance current is mainly affected by the battery and battery voltage and the conduction period. If the switch conduction period is constant during the balancing process, Since the battery is continuously released to the battery pack, the battery voltage will gradually decrease. As can be seen from equation (2), the balance current will be reduced, and the balance speed will be slower in the later stage of the balance. Similarly, the battery pack will be charged in the battery pack. When the battery is in a charging state, the battery voltage will rise. From the formula (4), the balance current will also decrease, resulting in a slower balancing speed. Therefore, the present invention controls the switching period of the switch to instantly adjust the balancing current. To shorten the time required for balance.

Fuzzy balance current control method and measurement platform:

Fuzzy control design:

According to equations (2) and (4), although the duty cycle mode can be adjusted according to the battery voltage change, the balance current can be maintained. However, due to the non-ideal characteristics of the circuit, and the nonlinear characteristics of the battery, the balance current cannot be accurately determined by simple mathematical formula. Adjustment, so the invention adds expert knowledge and experience, finds the relationship between conduction cycle and current and uses fuzzy control as control means, so that the balance circuit can adjust immediately under the premise that the battery voltage and battery voltage will change. The on period is to maintain a constant balance current. In order to realize the fuzzy control method for improving the battery balancing current, the present invention adds circuit practical considerations and battery application experience in the design of the rule base to control the primary side switch conduction period by feedback of the battery voltage and the battery voltage. The purpose is to adjust the balancing current in real time while ensuring the safe use of the circuit and the battery. Please refer to FIG. 6 , which illustrates an implementation architecture of the fuzzy control balance current method proposed by the present invention. The design method and steps of the fuzzy balance current controller of the present invention are described in detail below:

(1) Variable selection and attribution function design: There are two input variables of the fuzzy balance current controller of the present invention, which are a single battery voltage size V _B and a whole series battery voltage voltage V _PACK , and its attribution function is as shown in the figure 7 and FIG. 8, where a continuous triangle function is selected as the attribution function definition. Table 1. The semantic description of the input attribution function. In the domain of the argument, most of the lithium battery voltage is at least 3V, up to 4.2V, and the four batteries are connected in series to a battery voltage of at least 12V and a maximum of 16.8V. This attribution function divides the battery voltage from 3V to 4.2V and the battery voltage from 12V to 16.8V from low to high into five different degrees, which are sequentially defined as L to H.

Table 1. Semantic definition of input variable attribution function         <TABLE border="1" borderColor="#000000" width="_0005"><TBODY><tr><td> Battery Voltage Label Definition</td><td> Battery Pack Voltage Definition Definition</td></ Tr><tr><td> L: Low </td><td> L: Low </td></tr><tr><td> ML: Medium Low </td><td> ML: Medium Low </td></tr><tr><td> M: Medium </td><td> M: Medium </td></tr><tr><td> MH: Medium high </td><td > MH: Medium High </td></tr><tr><td> H: High </td><td> H: High </td></tr></TBODY></TABLE>

In terms of the output variable, since the output current can be changed by adjusting the on-period of the switch, the output variable is the on-period of the primary-side switch, and the secondary-side switch is complementary thereto. Since the balance current of the battery to the battery pack mode is mainly affected by the primary side switch conduction period, and the balanced current of the battery pack to the battery mode is mainly affected by the secondary side conduction period, the output variable is the primary side for the fuzzy control variable. The on-period of the switch, so the battery pack uses the secondary side switch on-cycle complement of the battery mode as the output attribution function, so the output variable has different on-period function ranges in the two operation modes. The output variable attribution function is determined by the characteristics actually measured by the circuit, with the goal of maintaining the same balanced current in both control modes. The output attribution function used in the present invention is shown in Figures 9a-9b, wherein Figure 9a is the attribution function of the battery to battery mode and Figure 9b is the attribution function of the battery to battery mode. Table 2 shows the semantic function of the attribution function. In terms of domain, the primary side conduction period is 52% to 62% in the battery-to-battery mode and 43% to 47% in the battery-to-battery mode. The table divides the values of the conduction periods of the two balance modes from small to large into five degrees, and from small to large, L to H.

Table 2. Semantic definition of output variable attribution function         <TABLE border="1" borderColor="#000000" width="_0006"><TBODY><tr><td> Primary Side Switch On Cycle Identification Definition</td></tr><tr><td> L : Low</td></tr><tr><td> ML: Medium to low</td></tr><tr><td> M: Medium</td></tr><tr><td > MH: Medium High </td></tr><tr><td> H: High </td></tr></TBODY></TABLE>

(2) Rule base : The rule base design principle of the fuzzy control balance current method is to determine the conduction period of the control balance current according to the instantaneous battery voltage and the battery pack voltage. When the balance mode of the battery is that the battery charges the battery pack, since the battery is in a discharge state, the voltage will gradually decrease as the balance progresses, thereby causing the balance current to decrease, and the fuzzy controller will increase the conduction period. Larger to increase the balancing current; if the battery charging current is greater than the balancing current and the voltage rises, the fuzzy controller will reduce the conduction period to reduce the balancing current. When the balancing circuit charges the battery for the battery pack, the battery voltage will rise, and the fuzzy controller will reduce the conduction period to maintain the balancing current, and vice versa. Table 3 is a rule base of the fuzzy balance current control method, and its rule base is expressed by the IF-THEN conditional expression.

(3) Inference engine and defuzzification: The inference engine of the fuzzy control equilibrium current method proposed by the present invention selects the minimum inference engine, and the defuzzification method uses the weighted average method.

Refer to Figure 10 for the three-dimensional relationship between the two inputs (battery voltage and battery voltage) and the fuzzy output (on cycle or duty cycle) of the fuzzy balance current control method of the present invention. It can be seen from Figure 10 how the changes in the input battery voltage and battery pack voltage affect the output conduction period. In the mode in which the battery charges the battery pack, if the battery voltage V _B decreases or the battery pack voltage V _pack rises, the conduction period increases; conversely, the conduction period decreases. In the mode in which the battery pack charges the battery, if the battery voltage V _B rises or the V _pack battery pack voltage drops, the conduction period decreases; otherwise, the conduction period increases.

Table 3. Rule base for fuzzy control equilibrium current method         <TABLE border="1" borderColor="#000000" width="_0007"><TBODY><tr><td><b>V_PACK V_B< /b></td><td><b>L</b></td><td><b>ML</b></td><td><b>M</b></ Td><td><b>MH</b></td><td><b>H</b></td></tr><tr><td><b>H</b> </td><td><b>L</b> rule 1 </td><td><b>L</b> rule 2 </td><td><b>ML</b> rule 3 </td><td><b>ML</b> Rule 4 </td><td><b>M</b> Rule 5 </td></tr><tr><td>< b>MH</b></td><td><b>L</b> rule 6 </td><td><b>ML</b> rule 7 </td><td><b >ML</b>rule 8 </td><td><b>M</b> rule 9 </td><td><b>M</b> rule 10 </td></tr> <tr><td><b>M</b></td><td><b>ML</b> Rule 11 </td><td><b>ML</b> Rule 12 </ Td><td><b>M</b> rule 13 </td><td><b>M</b> rule 14 </td><td><b>MH</b> rule 15 < /td></tr><tr><td><b>ML</b></td><td><b>ML</b> Rule 16 </td><td><b>M< /b>Rule 17 </td><td><b>M</b> Rule 18 </td><td><b>MH</b> Rule 19 </td><td><b>MH </b>rule 20 </td></tr><tr><td><b>L</b></td><td><b>M</b>rule 21 </td>< Td><b>M</b> rule 22 </td><td><b>MH</b> rule 23 </td><td><b>MH</b> rule 24 </td> <td><b>H</b> Rule 25 </td></tr></TBODY></TA BLE>

Measurement platform:

Since the battery pack needs to be monitored for a long time during battery balancing to record battery related data (such as voltage and temperature rise), the present invention uses the LabVIEW software introduced by National Instrument (NI). And with the company's peripheral hardware devices to achieve the monitoring interface. The developed human-machine interface can measure the battery voltage and temperature at the same time to send the I/O signal to stop the balance operation during over-temperature and over-voltage; and the developed human-machine interface can record the battery voltage and temperature during the balance for a long time. Data and store it in an Excel file. The present invention develops a LabVIEW measurement platform for long-term monitoring of battery voltage and temperature during balancing. The measurement tool uses a DAQ (Data Acquisition) system developed by National Instruments and converts battery voltage using NI USB-6009 DAQ. It is a digital signal, and the value is displayed on the human-machine interface for monitoring and storage into an Excel file. At the same time, through the software analysis, the corresponding I/O signal is sent to the DSP according to different voltage and temperature conditions for over-temperature and over-voltage protection. In the battery temperature measurement, the NI USB-9211 is used, and the value can be displayed on the human machine interface for monitoring and saving into an Excel file. Please refer to FIG. 11 , which is a structural diagram of battery voltage and temperature measurement. In addition to obtaining battery voltage and temperature per second for display and data storage, the monitoring program also uses the moving average method to process data to improve measurement accuracy, calculate the average battery voltage, and determine which balance mode the battery needs to perform. Calculate the maximum and minimum voltage difference and overvoltage and overtemperature protection. For an example of the LabVIEW monitoring interface, please refer to Figure 12.

Firmware programming:

FIG. 13 is a schematic diagram of an overall system architecture of the present invention, which first converts a battery and a battery pack voltage through a differential amplifier filter and then converts it into a digital signal via a microprocessor ADC (analog-to-digital), and then utilizes a finite impulse response. The (FIR) digital filter filters out the digital noise, inputs the filtered result to the fuzzy balance current controller for operation to obtain the corresponding switch on period, and finally drives the switch via the switch drive circuit. During the process, the battery voltage and temperature are also monitored by the human-machine interface system. If over-temperature or over-voltage protection occurs, the I/O signal is sent to the microprocessor to achieve digital control with protection function. In terms of the program flow, in addition to implementing the fuzzy balance current control method of the present invention, a multi-stage duty cycle adjustment method is additionally implemented to perform performance comparison with the fuzzy balance current control method of the present invention. The multi-stage duty cycle adjustment method divides the battery voltage into four stages, and the battery voltage is divided into five stages in each stage, and the corresponding on-period is adjusted according to the stage to maintain the balance current, and the adjustment curve used is used. As shown in Figures 14a-14b. It can be seen from the graph that the conduction period adjustment and the battery voltage change exhibit a nearly linear relationship, and it is known from the equations (1) and (3) that the adjustment method can keep the balance current at about 2A when the battery voltage changes. .

The main program starts with data memory, oscillator, interrupt, PWM (pulse width modulation), ADC (analog digital conversion), I/O (input and output), Timer (timer), FIR (finite impulse response). The initial settings of the required functions such as filters and fuzzy control are shown in Figure 15. Then enter a multi-stage duty cycle adjustment method battery balance subroutine or a fuzzy balance current control method balance subroutine, the flow shown in Figure 16, first read the battery and battery voltage, and enter the FIR filter, due to During the balance, the internal resistance of the battery will cause the measured battery voltage to be a non-open circuit voltage. Therefore, the balancer needs to terminate the action when measuring, and in order to avoid the constant balance current, the problem of excessive balance caused when the battery voltage is close will be First enter a balance time judgment subroutine, the flow is shown in Figure 17, this program will set the required balance time according to the maximum and minimum voltage difference of the battery, if the voltage difference is large, the cycle is 2 minutes. If the voltage difference is small, the cycle is 30 seconds. Next, it is determined according to the voltage condition of each battery, which balance mode is required. If the battery voltage is greater than the average battery voltage, the battery is charged to the battery pack charging mode, otherwise, the battery pack is charged to the battery charging mode, and then the balancer is performed. The switch is turned on, and finally the PWM signal is sent. After the set balance time is reached, the balance action will be paused, and then the next balance cycle will be executed. During the process, LabVIEW will monitor it in real time and over temperature and overvoltage. Send the signal to the microcontroller's I/O to stop the balancing operation.

Experimental results:

Experimental related parameter setting: The battery used in the experiment of the present invention is NCR18650B produced by Panasonic Corporation of Japan. The capacity of the battery is 3400 mAh, the rated voltage is 3.7V, the full-charge battery voltage is 4.2V, and the cut-off voltage is 2.75V. In terms of circuit hardware, the parameters are as shown in Table 4. Since the balance current of the demand is large, the bidirectional flyback circuit of the present invention operates in CCM (continuous conduction mode) in both equilibrium modes, after actual experiments. After considering the non-ideal factors, the range of the primary side conduction period of the fuzzy output is set to 52%~62% in the battery-to-battery mode, and the battery mode is 43%~47% in the battery mode, and the secondary side switching period is complementary thereto. And add about 3% of dead time to avoid simultaneous conduction of the switches on both sides.

Table 4. Circuit hardware parameters         <TABLE border="1" borderColor="#000000" width="_0008"><TBODY><tr><td> Parameter name </td><td> Value </td><td> Parameter name </td ><td> Value </td></tr><tr><td> Battery Voltage (V) </td><td> 3~4.2 </td><td> Dead Time (μs) </td ><td> 1 </td></tr><tr><td> Transformer turns ratio (N_P:N_S) </td><td > 8:32 </td><td> Primary Side Inductance (μH) </td><td> 15 </td></tr><tr><td> Switching Frequency (kHz) </td>< Td> 30 </td><td> Primary side leakage inductance (μH) </td><td> 1 </td></tr><tr><td> Battery life cycle range for battery pack mode (% ) </td><td> 52~62 </td><td> Battery pack duty cycle range (%) </td><td> 43~47 </td></tr></ TBODY></TABLE>

Battery balance curve:

The present invention separately performs a fuzzy control equilibrium current method and two conventional battery balance control methods, and compares the results to verify the superiority of the proposed method. 18 is a battery balance curve obtained by a conventional fixed duty cycle method, FIG. 19 is a battery balance curve obtained by a conventional multi-stage duty cycle adjustment method, and FIG. 20 is a battery balance obtained by the fuzzy control balance current method of the present invention. Graph. It can be observed from these figures that the system determines that the battery voltages of V _B1 and V _B2 are higher than the average voltage at the beginning of the balance, so that initially the battery is in the battery mode, the battery voltage drops, and V _B3 and V _{B4 are} lower than the average voltage, so At the beginning of the battery pair battery mode, the battery voltage rises. In this way, the voltage is judged and balanced in the balance process, and it can be known from the waveform that the battery voltage is effectively aligned through the balance.

Comparison of balance results:

Comparing the balance results of the above three balance control methods, Table 5 is the battery voltage values before and after the balance of the above three control methods, and Table 6 is the battery SOC (remaining battery capacity) values before and after the balance, and the SOC value is The OCV (open circuit voltage) is related to the SOC curve. It can also be seen from the table. Although this experiment uses voltage judgment to balance the battery, it can also achieve the effect of battery balance.

Table 5. Pre- and post-voltages for three control methods         <TABLE border="1" borderColor="#000000" width="_0009"><TBODY><tr><td> </td><td> Before Balance</td><td> After Balance</td> </tr><tr><td> Battery voltage</td><td> V_B1</td><td> V_B2</td><td > V_B3</td><td> V_B4</td><td> V_B1</td><td> V _B2</td><td> V_B3</td><td> V_B4</td></tr><tr ><td> Fixed Accountability Cycle Adjustment Method</td><td> 4.17V </td><td> 3.94V </td><td> 3.63V </td><td> 3.44V </td>< Td> 3.68V </td><td> 3.68V </td><td> 3.68V </td><td> 3.67V </td></tr><tr><td> Multi-stage responsibility cycle adjustment Method</td><td> 4.17V </td><td> 3.95V </td><td> 3.62V </td><td> 3.46V </td><td> 3.71V </td> <td> 3.70V </td><td> 3.69V </td><td> 3.69V </td></tr><tr><td> Fuzzy Controlled Equilibrium Current Method</td><td> 4.17 V </td><td> 3.94V </td><td> 3.63V </td><td> 3.44V </td><td> 3.72V </td><td> 3.71V </td> <td> 3.71V </td><td> 3.70V </td></tr></TBODY></TABLE>

Table 6. Pre- and post-remaining capacity of the three control methods         <TABLE border="1" borderColor="#000000" width="_0010"><TBODY><tr><td> </td><td> Before balance</td><td> After balance</td> </tr><tr><td> Remaining battery capacity</td><td> SOC₁</td><td> SOC₂</td>< Td> SOC₃</td><td> SOC₄</td><td> SOC₁</td><td> SOC₂</td><td> SOC₃</td><td> SOC₄</td></tr>< Tr><td> Fixed Accountability Cycle Adjustment Method</td><td> 100% </td><td> 81% </td><td> 48% </td><td> 20% </td> <td> 54% </td><td> 54% </td><td> 54% </td><td> 53% </td></tr><tr><td> Multi-stage responsibility cycle Adjustment method</td><td> 100% </td><td> 82% </td><td> 46% </td><td> 22% </td><td> 56% </td ><td> 55% </td><td> 55% </td><td> 55% </td></tr><tr><td> Fuzzy Controlled Equilibrium Current Method</td><td> 100% </td><td> 81% </td><td> 48% </td><td> 20% </td><td> 56% </td><td> 56% </td ><td> 56% </td><td> 55% </td></tr></TBODY></TABLE>

Finally, the balance results of the above three control methods are compared. As shown in Fig. 21 and Table 7, it can be known that the above three balance control methods have methods to complete the battery balance. Although the total SOC amount decreases after the balance, there are still 85. More than % balance efficiency, and in terms of balance time, the fixed responsibility cycle adjustment method takes 92 minutes to complete the balance, and the multi-stage responsibility cycle adjustment method reduces the balance time to 74 minutes, which is a 19% reduction time compared to the fixed responsibility cycle. Finally, the fuzzy control balance current method can shorten the balance time to only 58 minutes, and the phase method is reduced by 21% in the balance time. This result also proves that the fixed duty cycle method is used to balance the current to the later stage. The multi-stage duty cycle adjustment method can effectively improve the balance speed, and the fuzzy control balance method proposed by the present invention can adjust the on-period of the switch to maintain the constant current at a constant time, so the balance speed is more rapid and the duty cycle adjustment method is faster. That is, the experimental results prove that the fuzzy control of the present invention can effectively be based on the battery voltage immediately. Adjust the duty cycle to maintain the current balance, accelerate the speed of balance.

Table 7. Comparison of the balance results of the three control methods         <TABLE border="1" borderColor="#000000" width="_0011"><TBODY><tr><td> Project</td><td> Before Balance</td><td> After Balance</td ></tr><tr><td> Maximum battery voltage difference </td><td> Total SOC </td><td> Time required for balance (20mV) </td><td> Total SOC < /td></tr><tr><td> Fixed Accountability Cycle Adjustment Method</td><td> 730mV </td><td> 249% </td><td> 92 minutes</td><td > 215% </td></tr><tr><td> Multi-stage responsibility cycle adjustment method</td><td> 708mV </td><td> 250% </td><td> 74 minutes< /td><td> 222% </td></tr><tr><td> Fuzzy Control Equilibrium Current Method</td><td> 724mV </td><td> 249% </td><td > 58 minutes</td><td> 223% </td></tr></TBODY></TABLE>

The present invention has been disclosed in its preferred embodiments, and it is obvious that those skilled in the art will be able to illuminate the subject matter of the present invention without departing from the scope of the invention.

In summary, the present invention, regardless of its purpose, means and efficacy, is showing its technical characteristics different from the prior art, and its first invention is practical and practical, and is also in compliance with the patent requirements of the invention, and is requested to be examined by the reviewing committee. Pray for the patents at an early date.

100‧‧‧Bidirectional flyback circuit
110‧‧‧First analog-to-digital circuit
120‧‧‧Second analog-to-digital circuit
130‧‧‧Control unit
200‧‧‧ battery unit
300‧‧‧Battery Pack

1 is a block diagram of one embodiment of a smart fast battery balancer of the present invention. 2 illustrates a bidirectional flyback converter circuit of the present invention. 3a-3b are schematic diagrams showing the operation of the battery charging mode of the battery of the two-way flyback circuit of the present invention. 4a-4b are schematic diagrams showing the operation of the battery pack charging mode of the battery pack of the two-way flyback type circuit of the present invention. FIG. 5 is a conceptual diagram of a bidirectional flyback balancing circuit proposed by the present invention. FIG. 6 is a structural diagram of the fuzzy control balance current method adopted by the present invention. Figure 7 is a diagram showing the battery voltage attribution function taken in the present invention. Figure 8 is a diagram showing the voltage assignment function of the battery pack taken in the present invention. Figure 9a is a diagram showing the attribution function of the battery to battery mode of the present invention. Figure 9b is a diagram showing the assignment function of the battery pack to the battery mode of the present invention. FIG. 10 is a three-dimensional relationship diagram of two input-to-one fuzzy outputs taken by the present invention. Figure 11. depicts the battery voltage and temperature measurement architecture employed in the present invention. FIG. 12 is a schematic diagram of a LabVIEW monitoring human-machine interface taken by the present invention. FIG. 13 is a schematic diagram of the overall system architecture of the present invention. Figure 14a is a graph of battery-to-battery charging mode adjustment for a multi-stage duty cycle method. Fig. 14b is a graph showing the adjustment of the battery charging mode of the battery pack by a multi-stage duty cycle method. Figure 15 is a flow chart of a main program taken in the present invention. Figure 16 is a flow chart of a battery balancing subroutine taken in the present invention. Figure 17 is a flow chart of one of the balance time setting subroutines of the present invention. Figure 18 is a graph showing the battery balance curve of a fixed duty cycle method. Figure 19 is a diagram showing the battery balance curve of a multi-stage duty cycle adjustment method. Figure 20 is a diagram showing the battery balance curve of the fuzzy control balance current method adopted in the present invention. Figure 21 is a comparison of the balance results of the present invention and two conventional control methods.

100‧‧‧Bidirectional flyback circuit

110‧‧‧First analog-to-digital circuit

120‧‧‧Second analog-to-digital circuit

130‧‧‧Control unit

200‧‧‧ battery unit

300‧‧‧Battery Pack

Claims (5)

An intelligent fast battery balancer having: at least one bidirectional flyback circuit, each of the bidirectional flyback circuits having a first connection port, a first control end, a second connection port, and a second The first connection system of each of the two-way flyback circuits is electrically coupled to one of the battery cells of the battery pack, and the second connection port of each of the two-way flyback circuits is The first control end of each of the bidirectional flyback circuits is configured to receive a first switching signal, and each of the bidirectional flyback circuits is configured to be electrically coupled to the battery pack. The second control end is configured to receive a second switching signal to cause the battery pack to charge any of the battery cells or to charge any of the battery cells; and at least one first analogy a digital circuit, each for converting an analog voltage of the battery unit into a first digital signal; a second analog-to-digital circuit for converting an analog voltage of the battery to a second digital signal; One control And a method for performing a power transmission process between the battery pack and each of the battery cells according to the second digit signal and each of the first digit signals to be between each of the battery cells of the battery pack Reaching the voltage balance, wherein the power transmission program includes a conduction period fuzzy operation to determine one of the first switching signal and the second switching signal according to the second digital signal and a first digital signal a cycle, the duty cycle fuzzy operation includes inferring using a minimum inference engine according to a rule base, and the rule library divides the second digital signal and a first digital signal into a plurality of numerical levels to Corresponding to a plurality of numerical levels of the duty cycle. The smart fast battery balancer of claim 1, wherein the bidirectional flyback circuit comprises a transformer and two power switches. The smart fast battery balancer of claim 1, wherein the controller unit comprises a microcontroller. The smart fast battery balancer of claim 1, wherein the duty cycle fuzzy operation comprises performing a defuzzification operation using a weighted average method. The smart fast battery balancer of claim 1, further comprising a LabVIEW human machine interface to monitor the power transfer program.