CN-122001048-A - Voltage and SOC double closed-loop balance control method and system between two clusters of batteries

Abstract

The invention discloses a voltage and SOC double-closed-loop balance control method and system between two clusters of batteries, which comprises a battery management system BMS, a first battery cluster, a second battery cluster, a sampling module, a control and protection module and an equalization module comprising a DCDC equalization module and a parallel equalization module, wherein the sampling module collects the voltage of each battery cluster, the electrical parameters and the equalization current of the equalization module, the BMS acquires the SOC and the temperature of a battery core of the two clusters and sends the SOC and the temperature to the control and protection module, the control and protection module executes a first closed-loop control strategy for closed-loop test identification and dynamic equalization, generates an equalization starting instruction according to the difference between the voltage difference and the SOC, determines the equalization direction and judges whether to start the DCDC equalization or start the parallel equalization, and executes a second closed-loop control strategy by combining feedback of the sampling module. The invention can solve the problem of insufficient cooperativity of single parameter equalization, and eliminate equalization blind areas, thereby improving the energy utilization efficiency of two clusters of batteries.

Inventors

• ZHENG XIPENG
• CHEN SAICHUN
• Zou Lantu

Assignees

• 惠州市乐亿通科技股份有限公司

Dates

Publication Date

20260508

Application Date

20260407

Claims (10)

1. 1. The voltage and SOC double closed-loop equalization control system between two clusters of batteries is characterized by comprising a battery management system BMS, a first battery cluster, a second battery cluster, a sampling module, a control and protection module and an equalization module, wherein the equalization module comprises a DCDC equalization module and a parallel equalization module; the battery management system BMS is used for acquiring the charge state SOC1 of the first battery cluster, the charge state SOC2 of the second battery cluster and the highest temperature Tmax and the lowest temperature Tmin of the battery cells in the two battery clusters, and sending the charge state SOC1, the charge state SOC2 and the highest temperature Tmax and the lowest temperature Tmin to the control and protection module; The first battery cluster and the second battery cluster are respectively formed by connecting multiple strings of battery cells in series, and each battery cluster has equivalent internal resistance; The sampling module is respectively and electrically connected with the first battery cluster, the second battery cluster, the input side of the balancing module, the output side of the balancing module and the balancing main loop of the balancing module, and is used for collecting the interelectrode voltage V1 of the first battery cluster, the interelectrode voltage V2 of the second battery cluster, the voltage V3 of the input side of the balancing module, the voltage V4 of the output side of the balancing module and the balancing current I1 flowing through the balancing module; The control and protection module comprises a shunt tripping blank K1, a fuse F1 and a control unit, wherein the shunt tripping blank K1 is connected between the first battery cluster and the input side of the equalization module, the fuse F1 is connected between the output side of the equalization module and the second battery cluster, and the control unit is respectively in communication connection with the battery management system BMS, the sampling module, the DCDC equalization module and the parallel equalization module; the input end of the DCDC balancing module is connected with the first battery cluster through a shunt release blank K1, the output end of the DCDC balancing module is connected with the second battery cluster through a fuse F1, and the DCDC balancing module is specifically a bidirectional BUCK circuit architecture and is used for executing high-efficiency energy balance transfer when the voltage difference or SOC difference between the first battery cluster and the second battery cluster is greater than a first preset threshold value corresponding to the voltage difference or SOC difference; The parallel equalization module consists of a direct current contactor KM1 and equivalent internal resistances of two clusters of batteries, wherein the input end of the parallel equalization module is connected with a first battery cluster through one end of the direct current contactor KM1, and the output end of the parallel equalization module is connected with a second battery cluster through the other end of the direct current contactor KM1, and is used for executing low-loss energy balance transfer when the voltage difference or the SOC difference between the first battery cluster and the second battery cluster is less than or equal to a first preset threshold value corresponding to less than or equal to the second preset threshold value corresponding to more than or equal to the first preset threshold value; The control unit executes a first closed-loop control strategy for checking, identifying and dynamically balancing by receiving all electric sampling data of the sampling module and battery state data sent by the BMS, so as to generate a balancing starting instruction based on comprehensive judgment of a voltage difference and an SOC difference and determine a balancing mode selection signal, judges to start a corresponding target balancing module based on the balancing mode selection signal, dynamically generates a PWM driving signal to start DCDC balancing if the target balancing module is the DCDC balancing module, or generates an actuation instruction of a direct current contactor KM1 to start parallel balancing if the target balancing module is the DCDC balancing module, and simultaneously the sampling module diagnoses a main loop state according to voltages V1, V2, V3, V4, balancing current I1 and maximum temperature Tmax and feeds back to the control unit so as to execute a corresponding second closed-loop control strategy.
2. 2. The two-cluster inter-cell voltage and SOC dual closed-loop equalization control system of claim 1, wherein the first closed-loop control strategy executing check identification and dynamic equalization in the control and protection module to initiate DCDC equalization or parallel equalization comprises: After the system is electrified, the control unit establishes communication connection with the battery management system BMS, the sampling module, the DCDC balancing module and the parallel balancing module, receives a balancing function enabling instruction issued by the BMS, acquires rated voltage Ve, rated internal resistance Rn, preset target balancing current Ij and preset thresholds of all parameters of the first battery cluster and the second battery cluster, and generates a basic configuration parameter set; Based on basic configuration parameter set, real-time voltages V1 and V2 uploaded by a sampling module and SOC1, SOC2, tmax and Tmin uploaded by a BMS are circularly received, voltage difference absolute values delta V= |V1-V2| and SOC difference absolute values delta SOC= |SOC1-SOC2| are calculated, battery cell temperature extreme value data are obtained, and a real-time state and difference value data set is generated; Based on the real-time state and the difference data set, judging whether a temperature pre-protection condition is met, specifically, whether a temperature lower limit T_low is less than Tmin and Tmax is less than a temperature upper limit T_high, synchronously judging whether a double-balanced triggering condition is met, specifically, whether a double-balanced triggering condition delta V is greater than a first voltage threshold V_th1 or delta SOC is greater than a first SOC threshold SOC_th1, a double-balanced triggering condition delta V is less than a second voltage threshold V_th2 and delta SOC is less than a second SOC threshold SOC_th2, and performing logical AND operation on the judging results of the temperature pre-protection condition and the double-balanced triggering condition to generate a first closed loop checking result; if the first closed loop test result indicates that the temperature protection is not triggered and a double balance trigger condition is met or is not met, generating a balance start instruction and an energy transfer direction mark, wherein the energy transfer direction mark is determined according to the comparison of the sizes of V1 and V2 and the sizes of SOC1 and SOC2, and particularly is transferred from a battery cluster on one side with a large value to a battery cluster on one side with a small value; And executing a corresponding dynamic balance control strategy after starting the DCDC balance module or the parallel balance module.
3. 3. The system of claim 2, wherein determining the equalization mode selection signal in the corresponding direction to activate the DCDC equalization module or the parallel equalization module comprises: If the temperature protection is not triggered, comparing the absolute value DeltaV of the current voltage difference with a first voltage threshold value V_th1 and a second voltage threshold value V_th2 and comparing the absolute value DeltaSOC of the current SOC difference with a first SOC threshold value SOC_th1 and a second SOC threshold value SOC_th2 in real time, if DeltaV is greater than V_th1 or DeltaSOC is greater than SOC_th1, judging that a DCDC equalization mode is applicable, generating a first equalization mode selection signal and activating a driving interface corresponding to the DCDC equalization module, and if DeltaV is less than or equal to V_th1 and DeltaSOC is less than or equal to SOC_th1 and DeltaV is greater than or equal to V_th2 or DeltaSOC is greater than or equal to SOC_th2, judging that a parallel equalization mode is applicable, generating a second equalization mode selection signal and activating a driving interface corresponding to the parallel equalization module; The control unit sends a PWM driving signal containing initial duty ratio to the DCDC equalization module based on the target equalization module driving configuration set or sends an actuation instruction to a direct current contactor KM1 of the parallel equalization module, and synchronously reads real-time data of side voltages V3 and V4 and equalization current I1 fed back by the sampling module to generate a pre-action state verification data set; And analyzing a pre-action state verification data set, verifying whether the input-output voltage relation of the DCDC equalization module is consistent with the expected equalization direction or not, or verifying whether the loop on-off state of the direct current contactor KM1 of the parallel equalization module meets the instruction requirement or not, generating an equalization module ready confirmation signal if the loop on-off state passes the verification, and correspondingly controlling the direct current contactor KM1 to execute a closing action so as to respectively select to start the DCDC equalization module or the parallel equalization module.
4. 4. The dual closed-loop equalization control system of voltage and SOC between two clusters of cells of claim 3, wherein said executing a corresponding dynamic equalization control strategy after said starting of DCDC equalization module or parallel equalization module comprises: Determining a corresponding target equalization module based on the ready acknowledgement signal of the equalization module, continuously receiving real-time data V1, V2, V3, V4 and I1 uploaded by the sampling module and SOC1 and SOC2 uploaded periodically by the BMS, and generating a dynamic equalization real-time feedback data set; When the target equalization module is a DCDC equalization module, performing voltage and SOC dual closed-loop control based on a bidirectional BUCK circuit, namely establishing an outer loop SOC closed-loop controller, taking an SOC difference value delta SOC of a first battery cluster and an SOC difference value delta SOC of a second battery cluster as input, taking the final equality of the two battery clusters as a control target, performing operation processing through a preset proportional integral control algorithm, outputting a voltage reference value adjustment quantity delta V_ref for closed-loop control of the inner loop voltage, establishing an inner loop voltage closed-loop controller, taking a voltage difference delta V and the voltage reference value adjustment quantity delta V_ref as comprehensive input, eliminating the voltage difference between the two clusters as a direct control target, performing operation processing, outputting a PWM duty ratio correction quantity delta D for adjusting the corresponding equalization direction in the bidirectional BUCK circuit, generating an inner loop duty ratio correction instruction, combining the initial duty ratio D_real stored in a driving configuration set of the target equalization module, generating a PWM driving signal with dead time according to the equalization direction, and sending the PWM driving signal to a corresponding power switch control end in the DCDC module to adjust the power and perform DCDC driving and perform the equalization; When the target balancing module is a parallel balancing module, open loop control based on equivalent internal resistance current limiting is executed, namely, the continuous suction state of the direct current contactor KM1 is maintained, the size of balancing current I1 is determined by the voltage difference DeltaV of two clusters of batteries and the sum 2Rn of the total internal resistances of the two clusters of batteries, namely, I1=DeltaV/(2 Rn), the balancing current I1 is continuously monitored through a sampling module to drive the balancing current I1 to execute parallel balancing and transmit the balancing current to a control unit, the latest voltage difference DeltaV_new and the latest SOC difference DeltaSOC_new are calculated, whether a double balancing triggering condition is achieved is judged, and if the double balancing triggering condition is met, a balancing completion instruction is generated and the BMS is informed of balancing stopping.
5. 5. The two-cluster inter-cell voltage and SOC dual closed-loop equalization control system of claim 4, wherein the output voltage reference value adjustment amount Δv_ref comprises: Extracting SOC difference delta SOC_current of each period from a dynamic balance real-time feedback data set, calling a preset outer ring proportional coefficient Kp_soc and an outer ring integral coefficient Ki_soc to calculate a voltage reference value adjustment quantity, wherein the calculation expression is delta V_ref (k) =Kp_soc×delta SOC_current (k) +Ki_soc×Σdelta SOC_current (j), wherein k is a current control period sequence number, j is a historical period sequence number from control start to the current period, generating an original voltage adjustment quantity which is not subjected to amplitude limiting processing; The voltage reference value regulating quantity DeltaV_ref of the final current period is generated by carrying out first-order lag smoothing filtering on DeltaV_ref_limited subjected to amplitude limiting processing and the voltage reference value regulating quantity of the previous control period so as to inhibit high-frequency fluctuation components caused by SOC fluctuation or sampling noise, the voltage reference value regulating quantity DeltaV_ref is transmitted to an inner ring voltage closed-loop controller as a part of a voltage tracking target of the inner ring voltage closed-loop controller, and the SOC difference value and the voltage reference value regulating quantity DeltaV_ref of the current control period are stored for iterative operation of integral term accumulation calculation and smoothing filtering of the next control period.
6. 6. The system of claim 2, wherein the sampling module comprises a multi-channel voltage sampling unit, an equalizing current sampling unit, a synchronous signal conditioning and converting unit and a loop state on-line diagnosis unit; the multichannel voltage sampling unit is used for respectively acquiring interelectrode voltage V1 of the first battery cluster, interelectrode voltage V2 of the second battery cluster, voltage V3 at the input side of the equalization module and voltage V4 at the output side of the equalization module by adopting a voltage sensor to generate four paths of original voltage analog signals; The balanced current sampling unit is used for acquiring balanced current corresponding to the balanced main loop by adopting a Hall current sensor and generating a path of original current analog signal; The synchronous signal conditioning and converting unit is used for carrying out anti-aliasing filtering, isolation amplification, level shift and offset calibration treatment on four paths of original voltage analog signals and one path of original current analog signals so as to eliminate common-mode interference and high-frequency noise and generate five paths of conditioned analog signals, and also comprises an analog-to-digital converter ADC (analog-to-digital converter) which is used for carrying out synchronous sampling and high-resolution analog-to-digital conversion on the five paths of conditioned analog signals and generating a synchronous digital sampling data set comprising V1, V2, V3, V4 and I1; The loop state online diagnosis unit is used for receiving the synchronous digital sampling data set and diagnosing the operation state of the balanced main loop in real time according to the voltage logic relation and the current information: Judging the numerical value equality relation of V1, V3, V4 and V2 and the numerical value of I1, if V1 = V3 = V4 = V2 is met, diagnosing that a fuse F1 is fused to generate a first fault code, if V1 = V4 = V2 is met, diagnosing that a shunt tripping blank K1 is in an off state to generate a second fault code, if V1 = V3 = V2 and I1 = 0 is met, diagnosing that an equalization function is not started or a DCDC equalization module is not operated to generate a third state code, if V1 = V3 = V2 and I1 = 0 is met, diagnosing that the DCDC equalization module is operating to generate a fourth state code, and if V1 = V4 = V2 and I1 = 0 is met, diagnosing that a parallel equalization module is operating to generate a fifth state code; And combining the synchronous digital sampling data set with the generated state code or fault code and marking the time stamp to form a sampling and state diagnosis data set, and feeding back and uploading the sampling and state diagnosis data set to the control unit so as to execute a corresponding second closed-loop control strategy.
7. 7. The two-cluster inter-battery voltage and SOC dual closed-loop equalization control system of claim 6, wherein the loop status online diagnostic unit further comprises: The method comprises the steps of obtaining V1, V3, V4, V2 and I1 data sequences of a plurality of continuous sampling periods in a synchronous digital sampling data set, carrying out moving average filtering to effectively inhibit random sampling noise and short-term interference, generating a smoothed multi-period voltage and current data set, calculating the difference change rate between the adjacent sampling periods V3 and V4 and the change trend and fluctuation of I1 based on the multi-period voltage and current data set, and carrying out dynamic correction and state confirmation on a sampling and state diagnosis data set by combining the difference change rate and the change trend and the fluctuation: When the basic logic judges that the DCDC equalization module is running, if the difference change rate of V3 and V4 is detected to be continuously an extremely low value and the change trend of I1 is stable, the fluctuation is smaller than a preset threshold value, the DCDC equalization module is confirmed to be in a steady-state reduced-voltage energy transfer state to generate a steady-state DCDC running sub-state code, when the basic logic judges that the DCDC equalization module is running, if the difference change rate of V3 and V4 is detected to have a high-frequency pulsation component corresponding to PWM switching frequency and the waveform of I1 presents corresponding pulsation characteristics, the power switching tube in the DCDC equalization module is confirmed to be in a normal PWM switching state to generate a PWM switching running sub-state code, when the basic logic judges that the parallel equalization module is running, the theoretical calculation value is further calculated, the theoretical calculation value I1_cal= (V1-V2)/(2 Rn) is generated, and after the deviation of the actual measurement I1 and the I1_cal continuously exceeds the preset proportional threshold value, the parallel circuit contact resistance abnormal early warning code is generated and is added to the fifth state code; When the basic logic cannot be definitely matched with any preset condition, the historical state code sequence is called to track and infer the working mode, if the state code of the previous period is the fourth state code and the voltage relation of the current period meets v1=v3=v4=v2 and i1 is not equal to 0, the transient process that the equalizing mode is just switched from DCDC equalization to parallel equalization is judged to generate a mode switching transient identification code, and the corrected and confirmed final state code, sub-state code, early warning code or transient identification code is recombined and associated with the smoothed multicycle voltage and current data set to generate a high-reliability sampling and state diagnosis data set.
8. 8. The two cluster inter-battery voltage and SOC dual closed loop equalization control system of claim 7, wherein the feedback is uploaded to the control unit to implement a corresponding second closed loop control strategy comprises: If the sampling and state diagnosis data set fed back to the control unit confirms that the shunt tripping blank K1 and the fuse F1 are not normally disconnected, if so, the BMS is informed of the balance protection stop.
9. 9. The system of claim 1, wherein the bidirectional BUCK circuit is a non-isolated structure based on a bidirectional BUCK converter, and comprises a first filter capacitor C1, a second filter capacitor C2, a first power switch Q1, a second power switch Q2, a first freewheeling diode D1, a second freewheeling diode D2, and a power storage inductor L1; The first filter capacitor C1 is connected in parallel between the anode and the cathode of the first battery cluster; the second filter capacitor C2 is connected in parallel between the anode and the cathode of the second battery cluster; The power switch tube Q1, the second power switch tube Q2 and the power energy storage inductor L1 are connected in series between the first battery cluster and the second battery cluster, the power energy storage inductor L1 is connected between the first power switch tube Q1 and the second power switch tube Q2, a source electrode of the first power switch tube Q1 is connected with a positive electrode of the first battery cluster, a drain electrode of the first power switch tube Q1 is connected with one end of the power energy storage inductor L1, a source electrode of the second power switch tube Q2 is connected with a positive electrode of the second battery cluster, and a drain electrode of the second power switch tube Q2 is connected with the other end of the power energy storage inductor L1; The first freewheeling diode D1 is connected in parallel between the first filter capacitor C1 and the first power switch tube Q1, the anode of the first freewheeling diode D1 is connected with the cathode of the first battery cluster, and the cathode of the first freewheeling diode D1 is connected between the drain electrode of the first power switch tube Q1 and the power energy storage inductor L1; The second freewheeling diode D2 is connected in parallel between the second filter capacitor C2 and the second power switch tube Q2, the anode of the second freewheeling diode D2 is connected with the cathode of the second battery cluster, and the cathode of the second freewheeling diode D2 is connected between the drain of the second power switch tube Q2 and the power energy storage inductor L1; When the balancing direction is that the first battery cluster is transferred to the second battery cluster, the control unit controls the second power switch tube Q2 to keep on state, and applies the regulated PWM driving signal to the first power switch tube Q1, at this time, the first power switch tube Q1, the first freewheeling diode D1, the power storage inductor L1 and the second power switch tube Q2 form a first to BUCK converter from the first filter capacitor C1 to the second filter capacitor C2, wherein the first freewheeling diode D1 is used as a freewheeling path during the turn-off period of the Q1; When the balancing direction is that the second battery cluster is transferred to the second battery cluster, the control unit controls the first power switch tube Q1 to keep on state, and applies the regulated PWM driving signal to the second power switch tube Q2, at this time, the first power switch tube Q1, the second freewheeling diode D2, the power storage inductor L1 and the second power switch tube Q2 form a second bidirectional BUCK converter from the second filter capacitor C2 to the first filter capacitor C1, wherein the second freewheeling diode D2 is used as a freewheeling path during the period that Q2 is off.
10. 10. The method for controlling the voltage and the SOC between two clusters of batteries in a double closed-loop balance mode is realized based on the system for controlling the voltage and the SOC between two clusters of batteries in a double closed-loop balance mode according to any one of claims 1 to 9, and comprises the following steps: S01, system power-on initialization, wherein a control unit establishes communication connection with a battery management system BMS, a sampling module, a DCDC equalization module and a parallel equalization module, obtains rated parameters of a first battery cluster and a second battery cluster, preset target equalization current and preset thresholds of all parameters, and generates a basic configuration parameter set; S02, executing a first closed-loop control strategy, circularly acquiring inter-electrode voltages V1 and V2 of a first battery cluster and a second battery cluster, real-time states of charge SOC1 and SOC2, and the highest temperature Tmax and the lowest temperature Tmin of battery cells in the battery clusters, calculating a voltage difference DeltaV and an SOC difference DeltaSOC, and generating a real-time state and difference data set; based on the real-time state and the difference data set, judging whether a temperature pre-protection condition is met, a re-balance triggering condition is met or the dual-balance triggering condition is not met, if yes, generating a balance starting instruction and an energy transfer direction mark, determining a balance mode selection signal in the balance direction and the corresponding direction to start a DCDC balance module or a parallel balance module, otherwise, generating a balance closing instruction, returning to monitor again, determining a corresponding target balance module based on the balance mode selection signal, continuously receiving voltages V1, V2, V3 and V4 uploaded by a sampling module, balance current I1 and SOC2 uploaded periodically by a BMS, and generating a dynamic balance real-time feedback data set; s03, acquiring corresponding voltages V1, V2, V3 and V4, balanced current I1 and highest temperature Tmax, diagnosing a main loop state, confirming whether the shunt tripping idle switch K1 is not disconnected with the fuse F1 normally based on the main loop state, returning to S02 to execute the first closed loop control strategy again when confirming whether Tmax is less than the upper temperature limit T_high and whether the balanced current I1 is less than the balanced current threshold value if the current Tmax is less than the upper temperature limit T_high, disconnecting the shunt tripping idle switch K1 through a control unit if the current Tmax is not less than the balanced current threshold value, otherwise notifying the BMS to stop balanced protection, ending the balanced process, and returning to S02 to monitor continuously.

Description

Voltage and SOC double closed-loop balance control method and system between two clusters of batteries Technical Field The invention relates to the technical field of equalization control, in particular to a voltage and SOC double-closed-loop equalization control method and system between two clusters of batteries. Background In a high-voltage energy storage and vehicle-mounted battery system, in order to meet the requirements of the system on energy storage capacity and output power, a plurality of single batteries are generally connected in series to form a high-voltage battery pack, the high-voltage battery pack is defined as a battery cluster, and then the storage energy and the power supply stability of the whole system are improved through a parallel operation mode of a plurality of clusters of battery packs. The passive energy consumption balancing is to connect resistors in parallel at two ends of a battery cluster with higher voltage, so that redundant energy of the battery cluster is consumed in a form of resistance heating until the voltages of the two battery clusters are nearly consistent, and therefore voltage balancing among the battery clusters is achieved. The traditional active energy transfer equalization is the mainstream active equalization scheme at present, and the core of the traditional active energy transfer equalization scheme is that energy transfer between two clusters of batteries is realized through a bidirectional DCDC converter, DCDC mostly adopts an isolated full-bridge topology, and energy of a battery cluster with higher voltage or SOC is transferred to a battery cluster with lower voltage or SOC, so that inter-cluster equalization is realized. The system control balance is realized by mainly performing independent charge and discharge control on the two clusters of batteries, when the pressure difference between the clusters is large, increasing the charge quantity of the battery clusters with lower voltage, reducing the charge quantity of the battery clusters with higher voltage, and controlling the two clusters of batteries to run in parallel according to the system requirement after the voltage difference between the two clusters of batteries is reduced to a preset range. However, at present, the various equalization modes are only adjusted according to single parameters of voltage or SOC, so that cooperative equalization control of the voltage and the SOC cannot be realized, and thus, due to single equalization logic and insufficient cooperativity, the equalization requirements of two clusters of batteries under different operation conditions are difficult to comprehensively and systematically adapt, equalization dead zones exist, the problems of low equalization efficiency, accelerated decay of battery life and the like are easy to occur, and the energy utilization efficiency of the two clusters of batteries is reduced. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a voltage and SOC double closed-loop equalization control system between two clusters of batteries, which comprises a battery management system BMS, a first battery cluster, a second battery cluster, a sampling module, a control and protection module and an equalization module, wherein the equalization module comprises a DCDC equalization module and a parallel equalization module; the battery management system BMS is used for acquiring the charge state SOC1 of the first battery cluster, the charge state SOC2 of the second battery cluster and the highest temperature Tmax and the lowest temperature Tmin of the battery cells in the two battery clusters, and sending the charge state SOC1, the charge state SOC2 and the highest temperature Tmax and the lowest temperature Tmin to the control and protection module; The first battery cluster and the second battery cluster are respectively formed by connecting multiple strings of battery cells in series, and each battery cluster has equivalent internal resistance; The sampling module is respectively and electrically connected with the first battery cluster, the second battery cluster, the input side of the balancing module, the output side of the balancing module and the balancing main loop of the balancing module, and is used for collecting the interelectrode voltage V1 of the first battery cluster, the interelectrode voltage V2 of the second battery cluster, the voltage V3 of the input side of the balancing module, the voltage V4 of the output side of the balancing module and the balancing current I1 flowing through the balancing module; The control and protection module comprises a shunt tripping blank K1, a fuse F1 and a control unit, wherein the shunt tripping blank K1 is connected between the first battery cluster and the input side of the equalization module, the fuse F1 is connected between the output side of the equalization module and the second battery cluster, and the control unit is respectively in communication