Modularized isolation type full-bridge battery pack self-equalization circuit

Abstract

The invention discloses a modular isolation type full-bridge battery pack self-equalization circuit. The circuit comprises an isolation type pre-stage circuit constructed based on a full-bridge circuit, and a post-stage series voltage group SOC self-equalization rectification circuit, the isolation type pre-stage circuit constructed based on the full-bridge circuit comprises field-effect transistors S1, S2, S3 and S4, m single batteries ubattery 1, ubattery 2,..., ubattery (m) and a transformer T. The specific connection mode is as follows: the m single batteries ubattery 1, ubattery 2,..., ubattery (m) are connected in series to form a battery pack, the battery pack serves as an input source, and the positive electrode of the battery pack is connected with the drain electrode of the field-effect transistor S1 and the drain electrode of the field-effect transistor S3; the negative electrode of the battery pack is connected with the source electrode of the field effect transistor S2 and the source electrode of the field effect transistor S4. According to the modular isolation type full-bridge battery pack self-equalization circuit, electrical isolation is achieved, the number of battery pack ports can be expanded, the flexibility is high, and the practicability is high. And the SOC self-balancing of the battery pack is realized in a non-dissipative manner, so that the loss of the system is reduced, and the working efficiency of the system is improved.

Description

Technical Field

[0001] The invention relates to a self-balancing circuit for a series-connected battery pack, and in particular to a modular isolated full-bridge battery pack self-balancing circuit. Background Art

[0002] The voltage and capacity of a single lithium-ion battery are small. In order to meet the requirements of large capacity and high voltage in application scenarios, the voltage level is usually increased by connecting batteries in series. The inevitable inconsistency between the monomers after the lithium battery is grouped will reduce the energy utilization rate of the battery pack, shorten its cycle life, and even cause safety accidents. In order to improve the inconsistency of the battery pack, an effective balancing method must be introduced. At present, the main balancing topologies are divided into energy dissipative and non-dissipative types. The energy dissipative type is called passive balancing, which uses series resistance to consume the power of high-energy batteries to achieve the purpose of balancing. Its advantages are simple structure and low cost, but its disadvantages are large energy loss and severe heat generation. The non-dissipative type is called active balancing, which uses energy storage elements such as inductors, capacitors, and converters as energy transfer media to transfer battery energy from high to low, achieving balanced battery energy with high energy utilization. Active balancing is a hot spot in battery balancing technology due to its high energy utilization and flexible energy transfer.

[0003] For example, the patent document with application publication number CN118693955A discloses "an active balancing method based on a bidirectional flyback converter". This method uses the remaining capacity of the battery pack and the battery as the balancing control variable based on the active topology circuit of the bidirectional flyback converter, sets the balancing threshold, and starts and ends the management of the active balancing method according to the comparison result of the difference between the maximum capacity and the minimum capacity of the single battery between the battery packs. According to the state of the battery pack, the peak shaving mode is started to balance the discharge of the single battery with the maximum capacity, or the valley filling mode is started to balance the charge of the single battery with the minimum capacity. The energy adjustment of a single battery is achieved by peak shaving and valley filling, thereby achieving efficient battery balancing. However, the balancing circuit used in this control method includes multiple control switches, the logic control is complex, and it relies on complex control algorithms. Summary of the invention

[0004] In order to realize the automatic SOC balancing of multiple battery packs, the present invention proposes a modular isolated full-bridge battery pack self-balancing circuit, which realizes electrical isolation, the number of battery pack ports can be expanded, and the flexibility is high and the practicality is strong. The battery pack SOC self-balancing is realized in a non-dissipative manner, which reduces the loss of the system and improves the working efficiency of the system.

[0005] The technical solution adopted by the present invention is:

[0006] A modular isolated full-bridge battery pack self-balancing circuit, the circuit comprising: an isolated front-stage circuit constructed based on a full-bridge circuit, and a rear-stage series voltage group SOC self-balancing rectifier circuit;

[0007] The isolated front-stage circuit constructed based on the full-bridge circuit includes field effect transistors S1, S2, S3, S4, m single battery cells u battery1 、u battery2 、…、u battery(m) , transformer T, the specific connection form is as follows:

[0008] m single cells u battery1 、u battery2 、…、u battery(m) The battery pack is connected in series to form a battery pack, the battery pack is used as an input source, the positive electrode of the battery pack is connected to the drain of the field effect tube S1 and the drain of the field effect tube S3 respectively; the negative electrode of the battery pack is connected to the source of the field effect tube S2 and the source of the field effect tube S4 respectively;

[0009] Transformer T primary winding L p The positive end is connected to the source of field effect transistor S1 and the drain of field effect transistor S2 respectively;

[0010] Transformer T primary winding L p The negative end is connected to the source of the field effect tube S3 and the drain of the field effect tube S4 respectively;

[0011] The rear-stage series voltage group SOC self-balancing rectification circuit includes 2m diodes D 11 , D 12 , D 21 , D 22 ,…,D (m)1 , D (m)2 ; 2m capacitor C 11 , C 12 , C 21 , C 22 ,…,C (m)1 , C (m)2 ; m single cells u battery1 、u battery2 、…、u battery(m) , transformer T, where:

[0012] The first module unit includes capacitor C 11 , C 12 , diode D 11 , D 12 , single cell u battery1 ; Capacitor C 11 The negative end of the transformer T is connected to the secondary winding L s The positive terminal of capacitor C 11 The positive end of each diode is connected to the switching diode D11 The cathode of the switching diode D 12 The anode of the switching diode D 12 The cathode of each capacitor is connected to 12 The positive terminal of the battery u battery1 The positive electrode of the battery battery1 The negative pole of the transformer T is connected to the secondary winding L s The negative terminal of the switching diode D 11 Anode, capacitor C 12 The negative terminal;

[0013] The second module unit includes capacitor C 21 , C 22 , diode D 21 , D 22 , single cell u battery2 ; Capacitor C 11 The positive end of each diode is connected to the switching diode D 21 The cathode of the switching diode D 22 Anode of the switching diode D 22 The cathode of each capacitor is connected to 22 The positive terminal of the battery u battery2 The positive electrode of the battery battery2 The negative poles of the switching diodes D 21 Anode, capacitor C 22 The negative terminal;

[0014] The third module unit includes capacitor C 31 , C 32 , diode D 31 , D 32 , single cell u battery3 ; Capacitor C 31 The positive end of each diode is connected to the switching diode D 31 The cathode of the switching diode D 32 Anode of the switching diode D 32 The cathode of each capacitor is connected to 32 The positive terminal of the battery u battery3 The positive electrode of the battery battery3 The negative poles of the switching diodes D 31 Anode, capacitor C 32 The negative terminal;

[0015] .......and so on;

[0016] The mth module unit includes a capacitor C m1 , C m2 , diode D m1 , D m2 , single cell u batterym ; Capacitor Cm1 The positive end of each diode is connected to the switching diode D m1 The cathode of the switching diode D m2 Anode of the switching diode D m2 The cathode of each capacitor is connected to m2 The positive terminal of the battery u batterym The positive electrode of the battery batterym The negative poles of the switching diodes D m1 Anode, capacitor C m2 The negative terminal;

[0017] The connection between m module units is as follows:

[0018] Capacitor C 11 The positive terminal of the capacitor C 21 The negative terminal of capacitor C 21 The positive terminal of the capacitor C 31 The negative terminal of capacitor C 31 The positive terminal of the capacitor C 41 The negative terminal of capacitor C (m-1)1 The positive terminal of the capacitor C m 1 negative terminal; capacitor C 12 The positive terminal of the capacitor C 22 The negative terminal of capacitor C 22 The positive terminal of the capacitor C 32 The negative terminal of the capacitor C 32 The positive terminal of the capacitor C 42 The negative terminal of capacitor C (m-1)2 The positive terminal of the capacitor C m 2's negative terminal;

[0019] The connection form of m single cells is as follows:

[0020] Battery battery1 The positive terminal of the battery is connected to battery2 The negative electrode of the battery battery2 The positive terminal of the battery is connected to battery3 The negative electrode of the battery battery3 The positive terminal of the battery is connected to battery4 The negative electrode of the battery u battery(m-1) The positive terminal of the battery is connected to battery m of the negative electrode.

[0021] The upper and lower switches of the same bridge arm of the full-bridge port are complementary turned on, and the diagonal switches in the bridge are turned on at the same time, which can achieve a boost inverter effect and obtain a square wave voltage with a duty cycle of 50% at the winding port of the transformer T.

[0022] Take m=4 as an example:

[0023] A modular isolated full-bridge battery pack self-balancing circuit, the circuit comprising: an isolated front-stage circuit constructed based on a full-bridge circuit, and a rear-stage series voltage group SOC self-balancing rectifier circuit;

[0024] The isolated front-stage circuit constructed based on the full-bridge circuit includes field effect transistors S1, S2, S3, S4, and a battery pack u battery1 、u battery2 、u battery3 、u battery4 , transformer T, the specific connection form is as follows:

[0025] Battery Pack battery1 、u battery2 、u battery3 、u battery4 The battery pack is connected in series to form a battery pack, the battery pack is used as an input source, the positive electrode of the battery pack is connected to the drain of the field effect tubes S1 and S3, and the negative electrode of the battery pack is connected to the source of the field effect tubes S2 and S4; the primary winding L of the transformer T p The positive end of the transformer is connected to the source of the field effect tube S1 and the drain of the field effect tube S2. p The negative end is connected to the source of the field effect transistor S3 and the drain of the field effect transistor S4 respectively.

[0026] The rear-stage series voltage group SOC self-balancing rectification circuit includes a switching diode D 11 , D 12 , D 21 , D 22 , D 31 , D 32 , D 41 , D 42 , capacitor C 11 , C 12 , C 21 , C 22 , C 31 , C 32 , C 41 , C 42 , battery pack u battery1 、u battery2 、u battery3 、u battery4 , transformer T, the specific connection form is as follows:

[0027] The first module unit includes capacitor C 11 , C 12 , diode D 11 , D 12 , single cell u battery1 ; Capacitor C 11 The negative end of the transformer T is connected to the secondary winding Ls The positive terminal of capacitor C 11 The positive end of each diode is connected to the switching diode D 11 The cathode of the switching diode D 12 Anode of the switching diode D 12 The cathode of each capacitor is connected to 12 The positive terminal of the battery u battery1 The positive electrode of the battery battery1 The negative pole of the transformer T is connected to the secondary winding L s The negative terminal of the switching diode D 11 Anode, capacitor C 12 The negative terminal;

[0028] The second module unit includes capacitor C 21 , C 22 , diode D 21 , D 22 , single cell u battery2 ; Capacitor C 11 The positive end of each diode is connected to the switching diode D 21 The cathode of the switching diode D 22 Anode of the switching diode D 22 The cathode of each capacitor is connected to 22 The positive terminal of the battery u battery2 The positive electrode of the battery battery2 The negative poles of the switching diodes D 21 Anode, capacitor C 22 The negative terminal;

[0029] The third module unit includes capacitor C 31 , C 32 , diode D 31 , D 32 , single cell u battery3 ; Capacitor C 31 The positive end of each diode is connected to the switching diode D 31 The cathode of the switching diode D 32 Anode of the switching diode D 32 The cathode of each capacitor is connected to 32 The positive terminal of the battery u battery3 The positive electrode of the battery battery3 The negative poles of the switching diodes D 31 Anode, capacitor C 32 The negative terminal;

[0030] The fourth module unit includes capacitor C 41 , C 42 , diode D 41 , D 42 , single cell u battery4; Capacitor C 41 The positive end of each diode is connected to the switching diode D 41 The cathode of the switching diode D 42 Anode of the switching diode D 42 The cathode of each capacitor is connected to 42 The positive terminal of the battery u battery4 The positive electrode of the battery battery4 The negative poles of the switching diodes D 41 Anode, capacitor C 42 The negative terminal;

[0031] The connection between the 4 module units is as follows:

[0032] Capacitor C 11 The positive terminal of the capacitor C 21 The negative terminal of the capacitor C 21 The positive terminal of the capacitor C 31 The negative terminal of the capacitor C 31 The positive terminal of the capacitor C 41 The negative terminal;

[0033] Capacitor C 12 The positive terminal of the capacitor C 22 The negative terminal of the capacitor C 22 The positive terminal of the capacitor C 32 The negative terminal of the capacitor C 32 The positive terminal of the capacitor C 42 The negative terminal;

[0034] The connection form of 4 single batteries is as follows:

[0035] Battery battery1 The positive terminal of the battery is connected to battery2 The negative electrode of the battery battery2 The positive terminal of the battery is connected to battery3 The negative electrode of the battery battery3 The positive terminal of the battery is connected to battery4 of the negative electrode.

[0036] Contains four modes:

[0037] Mode 1: FETs S1 and S4 are turned off, FETs S2 and S3 are turned on, in the negative half cycle, the voltage of the secondary winding of transformer T is negative at the top and positive at the bottom, and diode D 11 , D 21 , D 31 , D 41 Conducting, diode D 12 , D 22 , D 32 , D 42 The secondary current of transformer T is supplied by the secondary winding L sThe negative terminal of the capacitor C 12 , C 22 , C 32 , C 42 Discharge, capacitor C 11 , C 21 , C 31 , C 41 Charge.

[0038] -u Ls =4ku battery

[0039] =u C11 =u C11 +u C21 +u C31 +u C41 -u C12 -u C22 -u C32 (1);

[0040] =u C11 +u C21 -u C12 =u C11 +u C21 +u C31 -u C12 -u C22

[0041] Mode 2: FETs S1 and S4 are turned on, FETs S2 and S3 are turned off, in the positive half cycle, the voltage on the secondary winding of transformer T is positive at the top and negative at the bottom, and diode D 12 , D 22 , D 32 , D 42 Conducting, diode D 11 , D 21 , D 31 , D 41 The secondary current of transformer T is supplied by the secondary winding L s The positive terminal of the capacitor C 11 , C 21 , C 31 , C 41 Discharge, capacitor C 12 , C 22 , C 32 , C 42 Charge.

[0042] u Ls =4ku battery

[0043] =u C12 -u C11 =u C12 +u C22+u C32 +u C42 -u C11 -u C21 -u C31 -u C41 (2);

[0044] =u C12 +u C22 -u C11 -u C21 =u C12 +u C22 +u C32 -u C11 -u C21 -u C31

[0045] where k = n s :n p According to the above modal analysis, combined with the inductor volt-second balance characteristics, the relationship between the capacitor voltages can be obtained:

[0046]

[0047] Expanded to m units, the relationship between the capacitor voltages is as follows:

[0048]

[0049] Field effect tubes S1 and S4 are turned on and in the positive half cycle, diode D 11 , D 21 , D 31 , D 41 When the reverse voltage is cut off, the battery pack is connected in series through the transformer T and the loop L s C 11 D 12 , L s C 11 C 21 D 22 , L s C 11 C 21 C 31 D 32 , L s C 11 C 21 C 31 C 41 D 42 To capacitor C 12 , C 22 , C 32 , C 42 Charging; Capacitor C 21 Through the diode D 12 , D 22 With capacitor C22 In parallel, the capacitor C 21 Voltage u C21 Equal to capacitance C 22 Voltage u C22 Similarly, capacitor C 31 Voltage u C31 Equal to capacitance C 32 Voltage u C32 , capacitor C 41 Voltage u C41 Equal to capacitance C 42 Voltage u C42 .

[0050] Field effect tubes S2 and S4 are turned on and in the negative half cycle, diode D 12 , D 22 , D 32 , D 42 When the reverse voltage is cut off, the battery pack is connected in series through the transformer T and the loop L s D 11 , L s C 12 D 21 , L s C 12 C 22 D 31 , L s C 12 C 22 C 32 D 41 To capacitor C 11 , C 21 , C 31 , C 42 Charging; Capacitor C 21 Through the diode D 11 , D 21 With capacitor C 12 In parallel, the capacitor C 21 Voltage u C21 Equal to capacitance C 12 Voltage u C12 Similarly, capacitor C 31 Voltage u C31 Equal to capacitance C 22 Voltage u C22 , capacitor C 41 Voltage u C41 Equal to capacitance C 32 Voltage u C32 .

[0051] When the capacitor is large enough, the capacitor voltage ripple can be ignored, u C21 =u C31 =u C41 =u C12=u C22 =u C32 =u C42 , the voltage of each battery cell is equal. Therefore, when the SOC of the single battery in the battery pack is unevenly distributed, the battery pack is connected in series as the input source of the front stage of the full bridge, and the excess energy can be redistributed through the back stage circuit, so that part of the energy of the series battery pack can be transferred to the battery cells with lower energy, achieving the balance of the battery pack SOC.

[0052] The present invention provides a modular isolated full-bridge battery pack self-balancing circuit, and the technical effects are as follows:

[0053] 1) The present invention realizes electrical isolation through a high-frequency transformer, thereby improving the reliability and safety of power supply.

[0054] 2) The number of ports of the battery pack of the present invention can be expanded, and it is highly flexible and practical.

[0055] 3) The present invention uses a non-dissipative method to achieve battery pack SOC self-balancing, which reduces system losses and improves system operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0057] Figure 1 This is a circuit schematic diagram of the present invention for achieving SOC balancing of a battery pack with four single cells in series;

[0058] Figure 2 This is a circuit schematic diagram of the present invention extended to SOC balancing of a battery pack with m single batteries connected in series;

[0059] Figure 3 This is a simulation diagram of the balancing effect of a battery pack with four single batteries connected in series when the present invention is adopted. DETAILED DESCRIPTION

[0060] Depend on Figure 1 A modular isolated full-bridge battery pack self-balancing circuit is shown, the circuit comprising: an isolated front-stage circuit constructed based on a full-bridge circuit, and a rear-stage series voltage group SOC self-balancing rectifier circuit;

[0061] The isolated front-stage circuit constructed based on the full-bridge circuit includes field effect tubes S1, S2, S3, S4, and a battery pack u battery1 、u battery2 、u battery3 、u battery4 , transformer T, the specific connection form is as follows:

[0062] Battery Pack battery1 、u battery2 、u battery3 、u battery4The phases are connected in series as input sources, and their positive electrodes are connected to the drains of field effect transistors S1 and S3, and their positive electrodes are connected to the sources of field effect transistors S2 and S4 respectively; the primary winding L of transformer T p The positive end is connected to the source of the field effect tube S1 and the drain of the field effect tube S2, and the negative end is connected to the source of the field effect tube S3 and the drain of the field effect tube S4.

[0063] The post-stage series voltage group SOC self-balancing rectifier circuit comprises a switching diode D 11 , D 12 , D 21 , D 22 , D 31 , D 32 , D 41 , D 42 , capacitor C 11 , C 12 , C 21 , C 22 , C 31 , C 32 , C 41 , C 42 , battery pack u battery1 、u battery2 、u battery3 、u battery4 , transformer T, the specific connection form is as follows:

[0064] Transformer T secondary winding L s The positive terminal of the capacitor C 11 The negative end of the transformer T secondary winding L s The negative end of each capacitor is connected to 12 The negative terminal of the switching diode D 11 Anode, battery u battery1 The negative pole of the switching diode D 11 The cathode of each capacitor is connected to 11 The positive terminal of capacitor C 21 The negative terminal of the switching diode D 12 Anode of the switching diode D 12 The cathode of each capacitor is connected to 12 The positive terminal of capacitor C 22 The negative terminal of the switching diode D 21 Anode, battery u battery1 Positive electrode, battery u battery2 The negative pole of the switching diode D 21 The cathode of each capacitor is connected to 21 The positive terminal of capacitor C 31 The negative terminal of the switching diode D 22 Anode of the switching diode D 22 The cathode of each capacitor is connected to22 The positive terminal of capacitor C 32 The negative terminal of the switching diode D 31 Anode, battery u battery2 Positive electrode, battery u battery3 The negative pole of the switching diode D 31 The cathode of each capacitor is connected to 31 The positive terminal of capacitor C 41 The negative terminal of the switching diode D 32 Anode of the switching diode D 32 The cathode of each capacitor is connected to 32 The positive terminal of capacitor C 42 The negative terminal of the switching diode D 41 Anode, battery u battery3 Positive electrode, battery u battery4 The negative pole of the switching diode D 41 The cathode of each capacitor is connected to 41 The positive terminal of the switching diode D 42 Anode of the switching diode D 42 The cathode of each capacitor is connected to 42 The positive terminal of the battery u battery4 The positive electrode.

[0065] Depend on Figure 2 As shown in Figure 1 The front stage circuit remains unchanged, and the back stage series voltage group SOC self-balancing rectifier circuit has the characteristics of scalability. One module unit includes capacitor C m1 , C m2 , diode D m1 , D m2 , battery u battery(m) Capacitor C m1 The positive end of each diode D m1 The cathode of diode D m2 Anode; Capacitor C m2 The positive end of each diode D m2 The cathode of the battery u battery(m) The positive electrode of capacitor C m2 The negative end of each diode is connected to m1 Anode, battery u battery(m) The negative terminal of capacitor C (m-1)1 The positive terminal of capacitor C (m-1)2 The positive end of each capacitor C in the adjacent module unit m1 The negative terminal of capacitor C m2 By connecting to the negative terminal of the battery pack, the number of battery pack ports can be expanded.

[0066] Depend on Figure 3It can be seen that the SOCs of the four battery packs are actually different, namely 70%, 85%, 90% and 95% respectively, and the other parameters are the same. The converter proposed in the present invention can realize the transfer of battery cells with higher SOC to battery cells with lower SOC, and finally the SOC of the four battery cells is balanced.

[0067] The present invention realizes electrical isolation, the number of battery pack ports can be expanded, the flexibility is high, and the practicability is strong. The battery pack SOC self-balancing is realized in a non-dissipative manner, the loss of the system is reduced, and the working efficiency of the system is improved.

Claims

1. A modular isolated full-bridge battery pack self-balancing circuit, characterized in that The circuit includes: an isolated front-stage circuit based on a full-bridge circuit, and a rear-stage series voltage group SOC self-balancing rectification circuit; The isolated front-stage circuit constructed based on the full-bridge circuit includes field effect transistors S1, S2, S3, S4, m single battery cells u battery1 、u battery2 、…、u battery(m) , transformer T, the specific connection form is as follows: m single cells u battery1 、u battery2 、…、u battery(m) The battery pack is connected in series to form a battery pack, the battery pack is used as an input source, the positive electrode of the battery pack is connected to the drain of the field effect tube S1 and the drain of the field effect tube S3 respectively; the negative electrode of the battery pack is connected to the source of the field effect tube S2 and the source of the field effect tube S4 respectively; Transformer T primary winding L p The positive end is connected to the source of field effect transistor S1 and the drain of field effect transistor S2 respectively; Transformer T primary winding L p The negative end is connected to the source of the field effect tube S3 and the drain of the field effect tube S4 respectively; The rear-stage series voltage group SOC self-balancing rectification circuit includes 2m diodes D 11 , D 12 , D 21 , D 22 ,…,D (m)1 , D (m)2 ; 2m capacitor C 11 , C 12 , C 21 , C 22 ,…,C (m)1 , C (m)2 ; m single cells u battery1 、u battery2 、…、u battery(m) , transformer T, where: The first module unit includes capacitor C 11 , C 12 , diode D 11 , D 12 , single cell u battery1 ; Capacitor C 11 The negative end of the transformer T is connected to the secondary winding L s The positive terminal of capacitor C 11 The positive end of each diode is connected to the switching diode D 11 The cathode of the switching diode D 12 Anode of the switching diode D 12 The cathode of each capacitor is connected to 12 The positive terminal of the battery u battery1 The positive electrode of the battery battery1 The negative pole of the transformer T is connected to the secondary winding L s The negative terminal of the switching diode D 11 Anode, capacitor C 12 The negative terminal; The second module unit includes capacitor C 21 , C 22 , diode D 21 , D 22 , single cell u battery2 ; Capacitor C 11 The positive end of each diode is connected to the switching diode D 21 The cathode of the switching diode D 22 Anode of the switching diode D 22 The cathode of each capacitor is connected to 22 The positive terminal of the battery u battery2 The positive electrode of the battery battery2 The negative poles of the switching diodes D 21 Anode, capacitor C 22 The negative terminal; The third module unit includes capacitor C 31 , C 32 , diode D 31 , D 32 , single cell u battery3 ; Capacitor C 31 The positive end of each diode is connected to the switching diode D 31 The cathode of the switching diode D 32 Anode of the switching diode D 32 The cathode of each capacitor is connected to 32 The positive terminal of the battery u battery3 The positive electrode of the battery battery3 The negative poles of the switching diodes D 31 Anode, capacitor C 32 The negative terminal; .......and so on; The mth module unit includes a capacitor C m1 , C m2 , diode D m1 , D m2 , single cell u batterym ; Capacitor C m1 The positive end of each diode is connected to the switching diode D m1 The cathode of the switching diode D m2 The anode of the switching diode D m2 The cathode of each capacitor is connected to m2 The positive terminal of the battery u batterym The positive electrode of the battery batterym The negative poles of the switching diodes D m1 Anode, capacitor C m2 The negative terminal; The connection between m module units is as follows: Capacitor C 11 The positive terminal of the capacitor C 21 The negative terminal of the capacitor C 21 The positive terminal of the capacitor C 31 The negative terminal of the capacitor C 31 The positive terminal of the capacitor C 41 The negative terminal of capacitor C (m-1)1 The positive terminal of the capacitor C m1 The negative terminal; Capacitor C 12 The positive terminal of the capacitor C 22 The negative terminal of the capacitor C 22 The positive terminal of the capacitor C 32 The negative terminal of the capacitor C 32 The positive terminal of the capacitor C 42 The negative terminal of capacitor C (m-1)2 The positive terminal of the capacitor C m2 The negative terminal; The connection form of m single cells is as follows: Battery battery1 The positive terminal of the battery is connected to battery2 The negative electrode of the battery battery2 The positive terminal of the battery is connected to battery3 The negative electrode of the battery battery3 The positive terminal of the battery is connected to battery4 The negative electrode of the battery u battery(m-1) The positive terminal of the battery is connected to batterym of the negative electrode.

2. A modular isolated full-bridge battery pack self-balancing circuit according to claim 1, characterized in that: The upper and lower switches of the same bridge arm of the full-bridge port are complementary turned on, and the diagonal switches in the bridge are turned on at the same time to achieve a boost inverter effect, and a square wave voltage with a duty cycle of 50% will be obtained at the winding port of the transformer T.

3. A modular isolated full-bridge battery pack self-balancing circuit, characterized in that The circuit includes: an isolated front-stage circuit based on a full-bridge circuit, and a rear-stage series voltage group SOC self-balancing rectification circuit; The isolated front-stage circuit constructed based on the full-bridge circuit includes field effect transistors S1, S2, S3, S4, and a battery pack u battery1 、u battery2 、u battery3 、u battery4 , transformer T, the specific connection form is as follows: Battery Pack battery1 、u battery2 、u battery3 、u battery4 The battery pack is connected in series to form a battery pack, the battery pack is used as an input source, the positive electrode of the battery pack is connected to the drain of the field effect tubes S1 and S3, and the negative electrode of the battery pack is connected to the source of the field effect tubes S2 and S4; the primary winding L of the transformer T p The positive end of the transformer is connected to the source of the field effect tube S1 and the drain of the field effect tube S2. p The negative end is connected to the source of the field effect tube S3 and the drain of the field effect tube S4 respectively; The rear-stage series voltage group SOC self-balancing rectification circuit includes a switching diode D 11 , D 12 , D 21 , D 22 , D 31 , D 32 , D 41 , D 42 , capacitor C 11 , C 12 , C 21 , C 22 , C 31 , C 32 , C 41 , C 42 , battery pack u battery1 、u battery2 、u battery3 、u battery4 , transformer T, the specific connection form is as follows: The first module unit includes capacitor C 11 , C 12 , diode D 11 , D 12 , single cell u battery1 ; Capacitor C 11 The negative end of the transformer T is connected to the secondary winding L s The positive terminal of capacitor C 11 The positive end of each diode is connected to the switching diode D 11 The cathode of the switching diode D 12 Anode of the switching diode D 12 The cathode of each capacitor is connected to 12 The positive terminal of the battery u battery1 The positive electrode of the battery battery1 The negative pole of the transformer T is connected to the secondary winding L s The negative terminal of the switching diode D 11 Anode, capacitor C 12 The negative terminal; The second module unit includes capacitor C 21 , C 22 , diode D 21 , D 22 , single cell u battery2 ; Capacitor C 11 The positive end of each diode is connected to the switching diode D 21 The cathode of the switching diode D 22 Anode of the switching diode D 22 The cathode of each capacitor is connected to 22 The positive terminal of the battery u battery2 The positive electrode of the battery battery2 The negative poles of the switching diodes D 21 Anode, capacitor C 22 The negative terminal; The third module unit includes capacitor C 31 , C 32 , diode D 31 , D 32 , single cell u battery3 ; Capacitor C 31 The positive end of each diode is connected to the switching diode D 31 The cathode of the switching diode D 32 The anode of the switching diode D 32 The cathode of each capacitor is connected to 32 The positive terminal of the battery u battery3 The positive electrode of the battery battery3 The negative poles of the switching diodes D 31 Anode, capacitor C 32 The negative terminal; The fourth module unit includes capacitor C 41 , C 42 , diode D 41 , D 42 , single cell u battery4 ; Capacitor C 41 The positive end of each diode is connected to the switching diode D 41 The cathode of the switching diode D 42 Anode of the switching diode D 42 The cathode of each capacitor is connected to 42 The positive terminal of the battery u battery4 The positive electrode of the battery battery4 The negative poles of the switching diodes D 41 Anode, capacitor C 42 The negative terminal; The connection between the 4 module units is as follows: Capacitor C 11 The positive terminal of the capacitor C 21 The negative terminal of capacitor C 21 The positive terminal of the capacitor C 31 The negative terminal of capacitor C 31 The positive terminal of the capacitor C 41 The negative terminal; Capacitor C 12 The positive terminal of the capacitor C 22 The negative terminal of capacitor C 22 The positive terminal of the capacitor C 32 The negative terminal of capacitor C 32 The positive terminal of the capacitor C 42 The negative terminal; The connection form of 4 single batteries is as follows: Battery battery1 The positive terminal of the battery is connected to battery2 The negative electrode of the battery battery2 The positive terminal of the battery is connected to battery3 The negative electrode of the battery battery3 The positive terminal of the battery is connected to battery4 of the negative electrode.

4. A modular isolated full-bridge battery pack self-balancing circuit according to claim 3, characterized in that: Contains four modes: Mode 1: FETs S1 and S4 are turned off, FETs S2 and S3 are turned on, in the negative half cycle, the voltage of the secondary winding of transformer T is negative at the top and positive at the bottom, and diode D 11 , D 21 , D 31 , D 41 Conducting, diode D 12 , D 22 , D 32 , D 42 Turn off; the secondary side current of transformer T is connected by the secondary winding L s The negative terminal of the capacitor C 12 , C 22 , C 32 , C 42 Discharge, capacitor C 11 , C 21 , C 31 , C 41 Charge; Mode 2: FETs S1 and S4 are turned on, FETs S2 and S3 are turned off, in the positive half cycle, the voltage on the secondary winding of transformer T is positive at the top and negative at the bottom, and diode D 12 , D 22 , D 32 , D 42 Conducting, diode D 11 , D 21 , D 31 , D 41 Turn off; the secondary side current of transformer T is connected by the secondary winding L s The positive terminal of the capacitor C 11 , C 21 , C 31 , C 41 Discharge, capacitor C 12 , C 22 , C 32 , C 42 Charge; where k = n s :n p According to the above modal analysis, combined with the inductor volt-second balance characteristics, the relationship between the capacitor voltages can be obtained:

5. A modular isolated full-bridge battery pack self-balancing circuit according to claim 3, characterized in that: Field effect tubes S1 and S4 are turned on and in the positive half cycle, diode D 11 , D 21 , D 31 , D 41 When the reverse voltage is cut off, the battery pack is connected in series through the transformer T and the loop L s C 11 D 12 , L s C 11 C 21 D 22 , L s C 11 C 21 C 31 D 32 , L s C 11 C 21 C 31 C 41 D 42 To capacitor C 12 , C 22 , C 32 , C 42 Charging; Capacitor C 21 Through the diode D 12 , D 22 With capacitor C 22 In parallel, the capacitor C 21 Voltage u C21 Equal to capacitance C 22 Voltage u C22 Similarly, capacitor C 31 Voltage u C31 Equal to capacitance C 32 Voltage u C32 , capacitor C 41 Voltage u C41 Equal to capacitance C 42 Voltage u C42 ; Field effect tubes S2 and S4 are turned on and in the negative half cycle, diode D 12 , D 22 , D 32 , D 42 When the reverse voltage is cut off, the battery pack is connected in series through the transformer T and the loop L s D 11 , L s C 12 D 21 , L s C 12 C 22 D 31 , L s C 12 C 22 C 32 D 41 To capacitor C 11 , C 21 , C 31 , C 42 Charging; Capacitor C 21 Through the diode D 11 , D 21 With capacitor C 12 In parallel, the capacitor C 21 Voltage u C21 Equal to capacitance C 12 Voltage u C12 Similarly, capacitor C 31 Voltage u C31 Equal to capacitance C 22 Voltage u C22 , capacitor C 41 Voltage u C41 Equal to capacitance C 32 Voltage u C32 ; When the capacitor is large enough, the capacitor voltage ripple can be ignored, u C21 =u C31 =u C41 =u C12 =u C22 =u C32 =u C42 , the voltage of each battery cell is equal; therefore, when the SOC of the single battery in the battery pack is unevenly distributed, the battery pack is connected in series as the input source of the front stage of the full bridge, and the excess energy can be redistributed through the rear stage circuit, so that part of the energy of the series battery pack can be transmitted to the battery cells with lower energy, achieving SOC balance of the battery pack.

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