Modular equalization circuit and method of controlling the same

Abstract

The application discloses a modular equalization circuit and a control method thereof. The modular equalization circuit comprises a power supply, a converter, a selection switch, a transformer, a rectifier circuit, a filter and a battery equalization circuit which are connected in sequence. The number of modules is N, the number of energy storage units in each module is M, and the number of the rectifier circuit, the transformer, the filter and the battery equalization circuit is N. The number of the selection switch is N+1. Two output ends of the converter are marked as A and B respectively, i represents the i-th module, when i is odd, the one end of the switch S i is connected with A, the other end of the switch S i is connected with the same name end of the primary side of the transformer T i . When i is even, the one end of the switch S i+1 is connected with B, the other end of the switch S i+1 is connected with the different name end of the primary side of the transformer T i . When i is even, the one end of the switch S i is connected with B, the other end of the switch S i+1 is connected with A. The application significantly shortens the equalization path, improves the equalization efficiency and has strong expansibility.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a modular equalization circuit and its control method for equalizing energy storage in energy storage systems. Background Technology

[0002] Series-connected lithium-ion batteries are now widely used in portable electronic devices, home appliances, and other commercial battery-powered applications. However, inherent tolerances between batteries are unavoidable. Combined with uneven temperature distribution and differences in aging, series-connected batteries gradually become unbalanced. When one battery reaches the limit of its permissible operating range, it will cause the entire battery pack to stop charging or discharging, resulting in the battery pack's capacity not being fully utilized. With repeated use of the battery pack, the inconsistency between individual cells will intensify, further deteriorating the overall characteristics of the lithium-ion battery pack. This makes it highly susceptible to overcharging and over-discharging of a few individual cells, leading to a significant degradation in battery pack performance. In extreme cases, it may even cause serious accidents such as combustion or explosion, severely hindering the widespread application of lithium-ion batteries.

[0003] Therefore, in series energy storage systems, it is usually necessary to introduce a balancing system to reduce the inconsistency between energy storage cells. The introduction of a balancing system can extend the system's operating time, improve the utilization rate of energy storage cells, prevent cells from being overcharged or over-discharged during operation, extend the cycle life of the battery pack, and ensure the safety of battery pack use.

[0004] Modular balancing technology is widely used in large-scale battery series energy storage systems due to its advantages such as fast balancing speed, high efficiency, and strong scalability. It consists of unit-level balancing circuits and module-level balancing circuits: unit-level balancing circuits balance the batteries within a module, while module-level balancing circuits achieve balancing between different modules.

[0005] High-voltage energy storage systems require scalable equalization structures, but high scalability can lead to reduced equalization speed and efficiency due to excessively long equalization paths. Conversely, pursuing higher equalization speed and efficiency increases the number of active switching transistors, resulting in higher costs. When a multi-winding transformer is used in the module equalization circuit, the winding difficulty of the multi-winding transformer increases with the increase in voltage level, i.e., the increase in the number of modules. This greatly limits the scalability of the topology, or the voltage stress on the module-level equalizer becomes too high when the voltage level increases, thus limiting the scalability of the topology.

[0006] Therefore, a modular equalization circuit with strong scalability, high equalization speed and efficiency, and low cost is urgently needed. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide a novel modular equalization circuit and its control method. This modular equalization circuit is low in cost, highly scalable, has high equalization speed and efficiency, a simple structure, and is easy to promote and use.

[0008] The technical solution adopted by the present invention to solve the aforementioned technical problem is as follows:

[0009] In a first aspect, the present invention provides a modular equalization circuit, comprising a unit-level equalization circuit and a module-level equalization circuit, wherein the unit-level equalization circuit and the module-level equalization circuit respectively realize voltage equalization of energy storage cells within and between groups; the modular equalization circuit includes a power supply, a converter, a selection switch, a transformer, a rectifier circuit, a filter, an intra-group equalization circuit, and N*M series-connected energy storage cells, wherein the number of modules is N, the number of energy storage cells in each module is M, and the number of rectifier circuits, transformers, filters, and intra-group equalization circuits are the same as the number of modules; the number of selection switches is N+1, denoted as S1 to S2. N+1 ;

[0010] Among them, the power supply, converter, selection switches S1-SN+1, transformer T1-transformer TN, rectifier circuit 1-rectifier circuit N, and filter 1-filter N constitute the module-level equalization circuit; the intra-group equalization circuit 1-intra-group equalization circuit N constitute the unit-level equalization circuit.

[0011] The power supply is directly connected to the converter, whose two output terminals are denoted as A and B, respectively. i represents the i-th module. When i is odd, switch S... i One end is connected to the output terminal A of the converter, and switch S i The other end is connected to transformer T i The first side of the same name w i1 Connected; Switch S i+1 One end is connected to the output terminal B of the converter, and switch S i+1 The other end is connected to transformer T i One side of the opposite end w i2 Connected;

[0012] When i is even, switch S i One end is connected to the output terminal B of the converter, and switch S i The other end is connected to transformer T i First side same name end w i1 Connected; Switch S i+1 One end is connected to the output terminal A of the converter, and switch S i+1 The other end is connected to transformer T i First-sided heteronym w i2 Connected;

[0013] The transformer T iThe secondary side is connected in sequence to rectifier circuit i, filter i, module i and group equalization circuit i.

[0014] The power source is at least one of a constant voltage source, a battery, and a supercapacitor; the converter is a DC-AC converter that outputs an adjustable pulse width alternating square wave, preferably at least one of a half-bridge inverter circuit, a full-bridge inverter circuit, or a push-pull inverter circuit, and the switching device used in the converter is at least one of a MOSFET or an IGBT.

[0015] The energy storage unit includes a battery or a supercapacitor. An energy storage unit can be a single cell or multiple batteries connected in series and parallel.

[0016] Select switches S1-SN+1 are composed of at least one of MOSFETs or relays;

[0017] The rectifier circuit 1 to rectifier circuit N are full-bridge rectifier circuits or full-wave rectifier circuits, and the switching devices in the rectifier circuits are diodes, MOSFETs or IGBTs;

[0018] The filters 1 to N are at least one of capacitor filtering, inductor filtering, compound filtering, or active RC filtering;

[0019] The group-level equalization circuits 1 to N are either passive or active equalization circuits. Passive equalization circuits include constant resistance equalization circuits or switched resistance equalization circuits, while active equalization circuits include Buck-Boost equalization circuits, switched capacitor equalization circuits, or multi-winding transformer equalization circuits.

[0020] The power supply uses a supercapacitor, and the converter is a full-bridge converter. Rectifier circuits 1-N use diode full-bridge rectification, filters 1-N use inductor-capacitor filtering, and the group equalization circuits 1-N use Buck-Boost converters. All active switching devices are MOSFETs. Q1-Q4 are the four switching transistors of the full-bridge converter, with two transistors on the same bridge arm conducting complementaryly at 180° intervals. Q1 and Q2 lead Q4 and Q3, respectively. T1-T N It is a two-winding power transformer, D 11 ~D 14 -D N1 ~D N4 These are the four rectifier diodes on the secondary side of the transformer, L1-L N It is the output filter inductor, C1-C N It is the output filter capacitor; Q 1-1 ~Q 1-4 -Q N-1 ~Q N-4It is the MOSFET, the switching device of the Buck-Boost converter. 1-1 ~L 1-2 -L N-1 ~L N-1 It is the inductor of the Buck-Boost converter;

[0021] When the i-th module is selected for connection, the specific electrical connection method of the module-level equalization circuit is as follows:

[0022] 1) When i is odd, the power supply V in Connected to a full-bridge converter (Q1~Q4), with the midpoint of the leading arm (Q1, Q2) of the full-bridge converter at point A and the midpoint of the lagging arm (Q3, Q4) at point B, the switch S connected to the midpoint A of the leading arm of the converter is closed. i The switch S connected to the lag bridge arm B of the closed converter i+1 Disconnect other switches to allow transformer T to... i The primary side is connected to A with the same name terminal and to B with the different name terminal. Transformer T i Secondary side and four rectifier diodes D i1 ~D i4 Connected, four rectifier diodes D i1 ~D i4 With output filter inductor L i and output filter capacitor C i Connected, output filter inductor L i The other end is connected to the switching device Q. i-1 Connected, output filter capacitor C i Connected in parallel across both ends of module i;

[0023] 2) When i is even, the power supply V in Connected to a full-bridge converter (Q1~Q4), with the midpoint of the leading arm (Q1, Q2) of the full-bridge converter at point A and the midpoint of the lagging arm (Q3, Q4) at point B, the switch S connected to the midpoint A of the leading arm of the converter is closed. i+1 The switch S connected to the lag bridge arm B of the closed converter i Disconnect other switches to allow transformer T to... i The primary side is connected to B with the same name terminal and to A with the different name terminal. Transformer T i Secondary side and four rectifier diodes D i1 ~D i4 Connected, four rectifier diodes D i1 ~D i4 With output filter inductor L i and output filter capacitor C i Connected, output filter inductor L i The other end is connected to the switching device Q. i-1 Connected, output filter capacitor Ci It is connected in parallel across both ends of module i.

[0024] Secondly, the present invention provides a balancing control method for the above-mentioned modular balancing circuit. The main control chip provides two pairs of complementary PWM waves for the module-level balancing circuit and one pair of complementary PWM waves for the unit-level balancing circuit. Each module is equipped with a battery measurement chip to detect the state of each battery in the module in real time, measure the battery voltage value, and transmit it to the main control chip via I2C communication. The main control chip obtains the battery voltage data of each module, compares the average voltage of each module, and drives the selection switch of the corresponding module to be turned on, thereby controlling the direction of the module-level balancing current. The unit-level balancing only requires one pair of complementary PWM waves to achieve self-balancing, without the need for an external measurement circuit.

[0025] The measurement period for module-level equalization is T. m At the beginning of each measurement cycle, the voltage of each battery module is measured, and the maximum battery module voltage V is obtained by comparison. BMmax With minimum battery module voltage V BMmin During the measurement period, when V BMmax With V BMmin The difference is greater than the set equalization action threshold voltage ΔV th At that time, the selector switch corresponding to the battery module with the lowest terminal voltage is turned on, and that battery module is in the charging state, and the next measurement is performed until time t is not less than the measurement period T. m When V BMmax With V BMmin The difference is less than the set equalization action threshold voltage ΔV th At this time, the module-level equalization ends. If time t is not less than the measurement period T... m Then proceed with voltage detection for the next cycle.

[0026] Compared with the prior art, the positive and progressive effects of the present invention are as follows:

[0027] In this invention, the unit-level balancing circuit provides balancing current to the individual battery cells within the module, while the module-level balancing circuit provides balancing current to different modules. The high-frequency switching transistor in the module-level balancing circuit is located on the auxiliary power supply side, reducing voltage stress on the high-frequency switching transistor. Simultaneously, the use of low-voltage switching transistors reduces costs. The module-level balancing circuit selects N+1 switches (N being the number of battery modules), significantly reducing the number of switches compared to existing technologies, further lowering costs. This invention's modular balancing circuit significantly shortens the balancing path, improves balancing efficiency, and accelerates balancing speed. Furthermore, it can be used in energy storage applications where any number of individual cells form any number of modules, offering strong scalability.

[0028] When the voltage level is increased, it will not affect the scalability of the circuit. The cost is moderate, there is no need to redesign the circuit structure, and there will be no excessive voltage stress. It truly achieves modularity, has excellent overall performance, and is easy to promote and use. Attached Figure Description

[0029] Figure 1 Overall structure diagram of the modular equalization circuit.

[0030] Figure 2 A schematic diagram of the circuit structure of one embodiment of a modular equalization circuit.

[0031] Figure 3 This is a diagram of the equilibrium control method.

[0032] Figure 4 This is a flowchart illustrating the specific process of the equalization control method of the present invention.

[0033] Figure 5 This is a graph showing the balancing process of module one in Example 1.

[0034] Figure 6 This is a graph showing the balancing process of module two in Example 1. Detailed Implementation

[0035] The present invention will be further explained below with reference to the embodiments and accompanying drawings, but this is not intended to limit the scope of protection of this application.

[0036] The modular equalization circuit of this invention consists of a unit-level equalization circuit and a module-level equalization circuit: the unit-level equalization circuit and the module-level equalization circuit respectively realize the equalization of battery voltage within and between groups, thereby realizing the equalization of the voltage of all batteries in the battery string. Figure 1 This is a schematic diagram of the overall structure of the modular equalization circuit of the present invention, including a power supply, converter, transformer, selection switch, rectifier circuit, filter, in-group equalization circuit, and N*M series-connected battery cells. The number of modules is N, and the number of battery cells in each module is M. The number of rectifier circuits, transformers, filters, and in-group equalization circuits are the same as the number of modules. The number of selection switches is N+1, denoted as S1 to S2. N+1 .

[0037] Among them, the power supply, converter, and selector switches S1-S N+1 The rectifier circuit 1-rectifier circuit N and the filter 1-filter N constitute the module-level equalization circuit; the intra-group equalization circuit 1-intra-group equalization circuit N is the unit-level equalization circuit.

[0038] The power source can be at least one of the following: constant voltage source, battery, supercapacitor, etc., and the power source is connected to the converter.

[0039] Converter: It is a DC-AC converter with an adjustable pulse width alternating square wave output. It can use half-bridge inverter circuit, full-bridge inverter circuit, push-pull inverter circuit, etc. The switching devices used in the converter can be implemented with MOSFET, IGBT and other devices.

[0040] Selector switches S1-SN+1: These can be composed of devices such as MOSFETs or relays. The output of the converter is connected to the primary side of the transformer via the selector switches. By controlling the opening and closing of the selector switches, the operating state of the subsequent circuits can be controlled. For example, closing switch S1 connected to the output A of the converter and switch S2 connected to the output B of the converter, and opening other switches, will allow transformer T1 and the subsequent circuits to operate while other branches do not operate.

[0041] Rectifier circuit 1 - Rectifier circuit N: can be a full-bridge rectifier circuit or a full-wave rectifier circuit, etc. The switching devices in the rectifier circuit can be diodes, MOSFETs or IGBTs, etc.

[0042] Filter 1 to Filter N: You can choose capacitor filtering, inductor filtering, compound filtering or active RC filtering, etc.

[0043] Intra-group equalization circuit 1-intra-group equalization circuit N: can be a passive equalization circuit, such as a constant resistance equalization circuit and a switched resistance equalization circuit, or an active equalization circuit, such as a Buck-Boost equalization circuit, a switched capacitor equalization circuit, a multi-winding transformer equalization circuit, etc.

[0044] The power supply is directly connected to the converter, whose two output terminals are denoted as A and B, respectively. i represents the i-th battery module. When i is an odd number, switch S... i One end is connected to the output terminal A of the converter, and switch S i The other end is connected to transformer T i The first side of the same name w i1 Connected; Switch S i+1 One end is connected to the output terminal B of the converter, and switch S i+1 The other end is connected to transformer T i One side of the opposite end w i2 Connected;

[0045] When i is even, switch S i One end is connected to the output terminal B of the converter, and switch S i The other end is connected to transformer T i First side same name end w i1 Connected; Switch S i+1 One end is connected to the output terminal A of the converter, and switch S i+1 The other end is connected to transformer T i First-sided heteronym wi2 Connected;

[0046] The transformer T i The secondary side is connected in sequence to rectifier circuit i, filter i, module i and group equalization circuit i.

[0047] like Figure 2 As shown, the power supply uses supercapacitors, the converter uses a full-bridge inverter circuit to implement a full-bridge converter, rectifier circuit 1 to rectifier circuit N uses diode full-bridge rectification, filter 1 to filter N uses inductor plus capacitor filtering, and the group equalization circuit 1 to group equalization circuit N uses a Buck-Boost converter. All active switching devices are MOSFETs. Figure 2 Q1 to Q4 are the four switching transistors of the full-bridge converter. The two transistors on the same bridge arm conduct complementaryly at 180° intervals. Q1 and Q2 lead Q4 and Q3, respectively. This design is to achieve soft switching of the transistors through the resonance between the inductor and the parasitic capacitance of the switching transistors. T1-T N It is a two-winding power transformer, D 11 ~D 14 -D N1 ~D N4 These are the four rectifier diodes on the secondary side of the transformer, L1-L N It is the output filter inductor, C1-C N It is the output filter capacitor. Q 1-1 ~Q 1-4 -Q N-1 ~Q N-4 It is the MOSFET, the switching device of the Buck-Boost converter. 1-1 ~L 1-2 -L N-1 ~L N-1 It is the inductor of the Buck-Boost converter. In the module-level equalization circuit, the equalization control method controls the selection switch to select the target module to be connected, thereby controlling the direction of the equalization current.

[0048] When the i-th module is selected for connection, the specific electrical connection method of the module-level equalization circuit is as follows:

[0049] 1. When i is odd, the power supply V in Connected to a full-bridge converter (Q1~Q4), with the midpoint of the leading arm (Q1, Q2) of the full-bridge converter at point A and the midpoint of the lagging arm (Q3, Q4) at point B, the switch S connected to the midpoint A of the leading arm of the converter is closed. i The switch S connected to the lag bridge arm B of the closed converter i+1 Disconnect other switches to allow transformer T to... i The primary side is connected to A with the same name terminal and to B with the different name terminal. Transformer T iSecondary side and four rectifier diodes D i1 ~D i4 Connected, four rectifier diodes D i1 ~D i4 With output filter inductor L i and output filter capacitor C i Connected, output filter inductor L i The other end is connected to the switching device Q. i-1 Connected, output filter capacitor C i It is connected in parallel across both ends of module i.

[0050] 2. When i is even, the power supply V in Connected to a full-bridge converter (Q1~Q4), with the midpoint of the leading arm (Q1, Q2) of the full-bridge converter at point A and the midpoint of the lagging arm (Q3, Q4) at point B, the switch S connected to the midpoint A of the leading arm of the converter is closed. i+1 The switch S connected to the lag bridge arm B of the closed converter i Disconnect other switches to allow transformer T to... i The primary side is connected to B with the same name terminal and to A with the different name terminal. Transformer T i Secondary side and four rectifier diodes D i1 ~D i4 Connected, four rectifier diodes D i1 ~D i4 With output filter inductor L i and output filter capacitor C i Connected, output filter inductor L i The other end is connected to the switching device Q. i-1 Connected, output filter capacitor C i It is connected in parallel across both ends of module i.

[0051] Figure 3 A method for equalization control of a modular equalization circuit is presented. The main control chip provides two pairs of complementary PWM waves for the module-level equalization circuit and one pair of complementary PWM waves for the unit-level equalization circuit. Each module is equipped with a battery measurement chip that monitors the state of each battery in the module in real time, measures the battery voltage value, and transmits it to the main control chip via I2C communication. The main control chip receives the battery voltage data from each module and compares the average voltage of each module. Based on this comparison, the main control chip drives the selection switch of the corresponding module to turn on, thereby controlling the direction of the module-level equalization current. Unit-level equalization only requires one pair of complementary PWM waves to achieve self-equalization, eliminating the need for external measurement circuitry.

[0052] The detailed control flowchart for module-level equalization is as follows: Figure 4 As shown, the measurement period for module-level equalization is T. mAt the beginning of each measurement cycle, the voltage of each battery module is measured, and the maximum battery module voltage V is obtained by comparison. BMmax With minimum battery module voltage V BMmin During the measurement period, when V BMmax With V BMmin The difference is greater than the set equalization action threshold voltage ΔV th At that time, the selector switch corresponding to the battery module with the lowest terminal voltage is turned on, and that battery module is in the charging state, and the next measurement is performed until time t is not less than the measurement period T. m When V BMmax With V BMmin The difference is less than the set equalization action threshold voltage ΔV th At this time, the module-level equalization ends. If time t is not less than the measurement period T... m Then proceed with voltage detection for the next cycle.

[0053] Example 1

[0054] In this embodiment, the battery string consists of two modules, each module comprising eight 18650 lithium-ion battery cells. Each cell has a rated capacity of 1.6 Ah and a rated voltage of 3.2 V, which are used for balancing experiments. The device model used in the experimental prototype is: the inductor L of the Buck-Boost converter. 1-1 ~L 1-7 and L 2-1 ~L 2-7 The inductance value is 15μH, and the switching transistor Q of the Buck-Boost converter is... 1-1 ~Q 1-14 and Q 2-1 ~Q 2-14 The model number is IRLB3813PBF, the selector switches S1-S3 are CSD88539, the full-bridge converter switching transistors Q1-Q4 are IRFP150NPBF, the driver chip for all switching transistors is SI8235BD-D-ISR, and the rectifier diode D... 1-1 ~D 1-4 and D 2-1 ~D 2-4 The model number is RB095T-90, the measurement chip is BQ76930, the output filter inductor (L1~L2) has an inductance value of 220μH, and the output filter capacitors C1~C2 have a capacitance value of 47μF.

[0055] Figure 5 and Figure 6The equalization process curves for module one and module two are presented separately. At the start of the equalization process, the maximum voltage difference between the sixteen cells in the two modules was 241.5mV. After 280 minutes of equalization, the maximum voltage difference dropped to 16.4mV, demonstrating a small voltage drop within a short period. The initial voltage of the cells in module one was higher than that in module two, and module one remained in a cell-level equalization state throughout. Module two underwent cell-level equalization first. After the cells within the module reached an equalization state, both the cell-level and module-level equalization circuits operated simultaneously. The module-level equalization circuit lagged behind the cell-level equalization circuit to prevent overcharging of individual cells with high initial voltages. The module-level equalization process is a charging equalization process, divided into constant current charging mode and constant voltage charging mode.

[0056] The modular equalization circuit of this invention offers fast equalization speed and high equalization efficiency under the same conditions. It also boasts good scalability. When a new module N+1 is introduced, the battery in module N+1 is connected in series after the existing modules. Simultaneously, a transformer, rectifier circuit, filter, and intra-module equalization circuit are added to the newly added module N+1. The transformer connected to the new module is determined based on whether N+1 has an odd or even number of cells. The newly introduced switch S... N+2 With the converter output and transformer T N+1 The connection method.

[0057] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A modular equalization circuit, comprising a unit-level equalization circuit and a module-level equalization circuit, wherein the unit-level equalization circuit and the module-level equalization circuit respectively achieve voltage equalization of individual energy storage cells within and between groups; characterized in that, The modular equalization circuit includes a power supply, converter, selection switches, transformer, rectifier circuit, filter, intra-group equalization circuit, and N*M series-connected energy storage units. The number of modules is N, and the number of energy storage units within each module is M. The number of rectifier circuits, transformers, filters, and intra-group equalization circuits are the same as the number of modules. The number of selection switches is N+1, denoted as S1~S2. N+1 ; Among them, the power supply, converter, selection switches S1-SN+1, transformer T1-transformer TN, rectifier circuit 1-rectifier circuit N, and filter 1-filter N constitute the module-level equalization circuit; the intra-group equalization circuit 1-intra-group equalization circuit N constitute the unit-level equalization circuit. The power supply is directly connected to the converter, whose two output terminals are denoted as A and B, respectively. i represents the i-th module. When i is odd, switch S... i One end is connected to the output terminal A of the converter, and switch S i The other end is connected to transformer T i The first side of the same name w i1 Connected; Switch S i+1 One end is connected to the output terminal B of the converter, and switch S i+1 The other end is connected to transformer T i One side of the opposite end w i2 Connected; When i is even, switch S i One end is connected to the output terminal B of the converter, and switch S i The other end is connected to transformer T i First side same name end w i1 Connected; Switch S i+1 One end is connected to the output terminal A of the converter, and switch S i+1 The other end is connected to transformer T i First-sided heteronym w i2 Connected; The transformer T i The secondary side is connected in sequence to rectifier circuit i, filter i, module i and group equalization circuit i.

2. The modular equalization circuit according to claim 1, characterized in that, The power source is at least one of a constant voltage source, a battery, and a supercapacitor; the converter is a DC-AC converter that outputs an adjustable pulse width alternating square wave; the converter is at least one of a half-bridge inverter circuit, a full-bridge inverter circuit, or a push-pull inverter circuit; and the switching device used in the converter is at least one of a MOSFET or an IGBT. The energy storage unit includes a battery or a supercapacitor; Select switches S1-SN+1 are composed of at least one of MOSFETs or relays; The rectifier circuit 1 to rectifier circuit N are full-bridge rectifier circuits or full-wave rectifier circuits, and the switching devices in the rectifier circuits are diodes, MOSFETs or IGBTs; The filters 1 to N are at least one of capacitor filtering, inductor filtering, compound filtering, or active RC filtering; The group-level equalization circuits 1 to N are either passive or active equalization circuits. Passive equalization circuits include constant resistance equalization circuits or switched resistance equalization circuits, while active equalization circuits include Buck-Boost equalization circuits, switched capacitor equalization circuits, or multi-winding transformer equalization circuits.

3. The modular equalization circuit according to claim 1, characterized in that, The power supply uses a supercapacitor, the converter is a full-bridge converter, rectifier circuit 1 to rectifier circuit N uses diode full-bridge rectification, filter 1 to filter N uses inductor plus capacitor filtering, and the group equalization circuit 1 to group equalization circuit N uses a Buck-Boost converter; all active switching devices are MOSFETs; Q1~Q4 are the four switches of the full-bridge converter, with the two switches in the same bridge arm conducting complementaryly at 180°, and Q1 and Q2 leading Q4 and Q3 respectively; T1-T N It is a two-winding power transformer, D 11 ~D 14 - D N1 ~D N4 These are the four rectifier diodes on the secondary side of the transformer. L 1- L N It is the output filter inductor. C 1 -C N It is the output filter capacitor; Q 1-1 ~Q1-4- Q N-1 ~Q N -4 represents the MOSFET, the switching device in the Buck-Boost converter. L 1-1 ~ L 1-2 - L N-1 ~ L N-1 It is the inductor of the Buck-Boost converter; When the i-th module is selected for connection, the specific electrical connection method of the module-level equalization circuit is as follows: 1) When i is odd, the power supply V in Connected to a full-bridge converter, with the midpoint of the leading arms Q1 and Q2 in the full-bridge converter at point A, and the midpoint of the lagging arms Q3 and Q4 at point B, the switch S connected to the midpoint A of the leading arms of the converter is closed. i The switch S connected to the lag bridge arm B of the closed converter i+1 Disconnect other switches to allow transformer T to... i The primary side is connected to A with the same name terminal and to B with the different name terminal. Transformer T i Secondary side and four rectifier diodes D i1 ~D i4 Connected, four rectifier diodes D i1 ~D i4 With output filter inductor L i and output filter capacitor C i Connected, output filter inductor L i The other end is connected to the switching device Q. i-1 Connected, output filter capacitor C i Connected in parallel across both ends of module i; 2) When i is even, the power supply V in Connected to a full-bridge converter, with the midpoint of the leading arms Q1 and Q2 in the full-bridge converter at point A, and the midpoint of the lagging arms Q3 and Q4 at point B, the switch S connected to the midpoint A of the leading arms of the converter is closed. i+1 The switch S connected to the lag bridge arm B of the closed converter i Disconnect other switches to allow transformer T to... i The primary side is connected to B with the same name terminal and to A with the different name terminal. Transformer T i Secondary side and four rectifier diodes D i1 ~D i4 Connected, four rectifier diodes D i1 ~D i4 With output filter inductor L i and output filter capacitor C i Connected, output filter inductor L i The other end is connected to the switching device Q. i-1 Connected, output filter capacitor C i It is connected in parallel across both ends of module i.

4. A method for equalization control of the modular equalization circuit according to any one of claims 1-3, characterized in that, The main control chip provides two pairs of complementary PWM waves for the module-level equalization circuit and one pair of complementary PWM waves for the unit-level equalization circuit. Each module is equipped with a battery measurement chip to detect the status of each battery in the module in real time, measure the battery voltage value, and transmit it to the main control chip via I2C communication. The main control chip obtains the battery voltage data of each module, compares the average voltage of each module, and drives the selection switch of the corresponding module to turn on, thereby controlling the direction of the module-level equalization current. Unit-level equalization only requires a pair of complementary PWM waves to achieve self-equalization, without the need for external measurement circuitry; The measurement cycle for module-level equalization is T m At the beginning of each measurement cycle, the voltage of each battery module is measured, and the maximum battery module voltage is obtained by comparison. V BMmax With minimum battery module voltage V BMmin During the measurement period, when V BMmax and V BMmin The difference is greater than the set equalization action threshold voltage Δ V th At that time, the selector switch corresponding to the battery module with the lowest terminal voltage is turned on, and that battery module is in the charging state, and the measurement is performed at the next moment until time t is not less than the measurement period. T m ;when V BMmax and V BMmin The difference is less than the set equalization action threshold voltage Δ V th When the module-level equalization ends; if time t is not less than the measurement period. T m Then proceed with voltage detection for the next cycle.

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