Active equalization circuit of series battery pack based on Boost converter

Abstract

The invention discloses a series battery pack active equalization circuit based on a Boost converter. The equalization circuit comprises an n-path output boost converter, n-1 bridging capacitors and n battery units, the n-path output boost converter comprises an inductor L, a power switch S, a first-path output diode D1 and a first-path output capacitor C1; the circuit comprises a first-path output diode D1, a second-path output diode D2, a second-path output capacitor C2, a first-path bridging capacitor Cp1 and a first-path clamping diode Dp1. A third output triode D2, a third output capacitor C3, a second bridging capacitor Cp2 and a second clamping diode Dp2; and the like, an nth output diode Dn, an nth output capacitor Cn, an (n-1) th bridging capacitor Cp (n-1) and an (n-1) th clamping diode Dp (n-1). According to the invention, automatic voltage sharing among the battery units is realized through the bridging capacitor, no complex sampling and control algorithm is needed, the problem of terminal voltage imbalance caused by cross adjustment rate during multi-winding output of the transformer is avoided, the voltage deviation is effectively reduced, and the battery equalization precision is improved.

Description

Technical Field

[0001] The invention relates to a battery pack balancing circuit, and in particular to an active balancing circuit for a series battery pack based on a Boost converter. Background Art

[0002] Lithium-ion batteries dominate the field of electric vehicle power batteries due to their excellent energy density, long cycle life, no memory effect, and high efficiency and environmental protection. However, the voltage and capacity of single cells limit their ability to directly meet the high performance requirements of electric vehicles. Therefore, a battery pack consisting of multiple batteries connected in series and parallel becomes a necessary choice. However, this combination also brings new challenges: manufacturing differences, usage environments, and different charging and discharging modes lead to different performance of single cells in the battery pack, such as mismatch in capacity, voltage, and internal resistance, which not only affects the durability and reliability of the battery pack, but also poses a threat to safety.

[0003] To solve this problem, battery balancing technology came into being, aiming to ensure the performance balance of each single cell in the battery pack. At present, balancing technology is mainly divided into two categories: passive balancing and active balancing. Passive balancing consumes excess energy through resistance, but this method not only causes energy waste, but also may damage battery performance due to high temperature environment. In contrast, active balancing technology is achieved through energy transfer, such as the balancing control method based on buck-boost converter proposed in CN113489083A patent. This method introduces energy storage inductors, diodes and balancing control switches into the battery pack, and realizes energy transfer from high-energy batteries to low-energy batteries by controlling the opening and closing of the switch, effectively promoting battery balancing. Furthermore, by combining single cells into modules of different levels and achieving balancing between each level through logical control, not only the energy distribution between adjacent batteries is optimized, but also the balancing of non-adjacent batteries is indirectly achieved, significantly improving the balancing efficiency of the battery pack. However, the complexity of this method lies in its balancing circuit design, which involves fine logical control of multiple control switches, which undoubtedly increases the difficulty of technical implementation. Summary of the invention

[0004] In order to solve the shortcomings of the existing battery pack balancing technology, the present invention proposes an active balancing circuit for a series battery pack based on a Boost converter, which is composed of a multi-output boost converter and a plurality of cross-over capacitors. Based on the boost circuit, a multi-output boost circuit topology is adopted, and the terminal voltage balance (same) of the battery cells inside the battery pack is achieved by adding a cross-over capacitor between each output. Compared with the traditional multi-series boost circuit balancing structure, the active balancing circuit of the present invention realizes automatic voltage balancing between battery cells through cross-over capacitors, without the need for complex sampling and control algorithms; and avoids the problem of terminal voltage imbalance caused by the cross-regulation rate when the multi-series boost circuit is output, effectively reducing voltage deviation and improving battery balancing accuracy.

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

[0006] The active balancing circuit of a series battery pack based on a Boost converter comprises:

[0007] An n-output boost converter, n-1 cross-capacitors and n battery cells;

[0008] The n-channel output boost converter includes an inductor L, a power switch S, a first channel output diode D1, and a first channel output capacitor C1;

[0009] The second output diode D2, the second output capacitor C2, the first jumper capacitor C p1 , the first clamping diode D p1 ;

[0010] The third output transistor D2, the third output capacitor C3, the second jumper capacitor C p2 , the second clamping diode D p2 ;

[0011] ... and so on.

[0012] The nth output diode D n , the nth output capacitor C n , the n-1th cross-connect capacitor C p(n-1) , the n-1th clamping diode D p(n-1) ;

[0013] One end of the inductor L is connected to the cathode of the output diode D1, one end of the first output capacitor C1, and the positive electrode of the battery B1.

[0014] The other end of the inductor L is connected to the drain of the switch S and the positive electrode of the output diode D1 respectively, and the negative electrode of the battery B1 is connected to the other end of the first output capacitor C1 and the source of the switch S respectively;

[0015] Among the n-1 jumper capacitors,

[0016] The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the second output diode D2 is connected to one end of the second output capacitor C2 and the positive electrode of the battery B2, and the negative electrode of the battery B2 is connected to the other end of the second output capacitor C2 and the first clamping diode D p1 anode;

[0017] The second bridge capacitor C p2 The other end is connected to the second clamping diode D p2 The cathode of the third output diode D2 is connected to one end of the third output capacitor C3 and the positive electrode of the battery B3 respectively, and the negative electrode of the battery B3 is connected to the other end of the third output capacitor C3 and the second clamping diode D p2 anode;

[0018] The third bridge capacitor C p3 The other end is connected to the third clamping diode D p3 The cathode of the fourth output diode D4 is connected to one end of the fourth output capacitor C4 and the positive electrode of the battery B4 respectively, and the negative electrode of the battery B4 is connected to the other end of the fourth output capacitor C4 and the third clamping diode D p3 anode;

[0019] ... and so on.

[0020] The n-1th cross-connect capacitor C p(n-1) The other end is connected to the n-1th clamping diode D p(n-1) Cathode, nth output diode D n Anode, nth output diode D n The cathode is connected to the nth output capacitor C n One end, battery B n Positive electrode, battery B n The negative electrode is connected to the nth output capacitor C n The other end, the n-1th clamping diode D p(n-1) anode;

[0021] The anode of the first output diode D1 is connected to the first jumper capacitor C p1 One end, the second cross-connect capacitor C p2 One end, the third way cross-connect capacitor C p3 One end, ... and so on, the n-1th path is connected across the capacitor C p(n-1) one end;

[0022] The other end of the first output capacitor C1 is connected to one end of the second output capacitor C2;

[0023] The other end of the second output capacitor C2 is connected to one end of the third output capacitor C3;

[0024] The other end of the third output capacitor C3 is connected to one end of the fourth output capacitor C4;

[0025] ... and so on.

[0026] Output capacitor C of the n-1th channel n-1 The other end is connected to the nth output capacitor C n one end;

[0027] The nth output capacitor C n The other end is connected to the source of switch S.

[0028] The gate of the power switch S is connected to a controller, and its duty cycle can be changed between 0 and 1.

[0029] An active balancing circuit based on a Boost converter and containing four single batteries connected in series, the balancing circuit comprising:

[0030] A 4-way output boost converter, 3 jumper capacitors and 4 battery cells;

[0031] The 4-way output boost converter includes an inductor L, a power switch S, a first output diode D1, and a first output capacitor C1;

[0032] The second output diode D2, the second output capacitor C2, the first jumper capacitor C p1 , the first clamping diode D p1 ;

[0033] The third output transistor D2, the third output capacitor C3, the second jumper capacitor C p2 , the second clamping diode D p2 ;

[0034] The fourth output transistor D4, the fourth output capacitor C4, the third jumper capacitor C p3 , the third clamping diode D p3 ;

[0035] One end of the inductor L is connected to the cathode of the output diode D1, one end of the first output capacitor C1, and the positive electrode of the battery B1.

[0036] The other end of the inductor L is connected to the drain of the switch S and the positive electrode of the output diode D1 respectively, and the negative electrode of the battery B1 is connected to the other end of the first output capacitor C1 and the source of the switch S respectively;

[0037] Among the 3 jumper capacitors,

[0038] The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the second output diode D2 is connected to one end of the second output capacitor C2 and the positive electrode of the battery B2, and the negative electrode of the battery B2 is connected to the other end of the second output capacitor C2 and the first clamping diode D p1 anode;

[0039] The second bridge capacitor C p2 The other end is connected to the second clamping diode D p2 The cathode of the third output diode D2 is connected to one end of the third output capacitor C3 and the positive electrode of the battery B3 respectively, and the negative electrode of the battery B3 is connected to the other end of the third output capacitor C3 and the second clamping diode D p2 anode;

[0040] The third bridge capacitor C p3 The other end is connected to the third clamping diode D p3 The cathode of the fourth output diode D4 is connected to one end of the fourth output capacitor C4 and the positive electrode of the battery B4 respectively, and the negative electrode of the battery B4 is connected to the other end of the fourth output capacitor C4 and the third clamping diode D p3 anode;

[0041] The anode of the first output diode D1 is connected to the first jumper capacitor C p1 One end, the second cross-connect capacitor C p2 One end, the third way cross-connect capacitor C p3 one end;

[0042] The other end of the first output capacitor C1 is connected to one end of the second output capacitor C2;

[0043] The other end of the second output capacitor C2 is connected to one end of the third output capacitor C3;

[0044] The other end of the third output capacitor C3 is connected to one end of the fourth output capacitor C4;

[0045] The other end of the fourth output capacitor C4 is connected to the source of the switch S.

[0046] Take a battery pack consisting of four single cells B1, B2, B3, and B4 in series as an example. When the power switch S is turned on, the clamping diode D p1 , clamping diode D p2 and clamping diode D p3The first output diode D1, the second output diode D2, the third output diode D3 and the fourth output diode D4 are turned off. The power supply charges the energy storage inductor L, and the current of the inductor L increases. The output capacitor C1 charges the battery B1, and the cross-connected capacitor C p1 To charge the output capacitor C2 and battery B2, the capacitor C p2 To charge the output capacitor C3 and battery B3, the cross-capacitor C p3 Charge the output capacitor C4 and the battery B4.

[0047] When the power switch S is turned off, the clamping diode D p1 , clamping diode D p2 and clamping diode D p3 The first output diode D1, the second output diode D2, the third output diode D3 are turned off, and the fourth output diode D4 is turned on. The power supply and the energy storage inductor L jointly supply the output capacitor C1, the battery B1, and the jumper capacitor C p1 , cross-capacitor C p2 , cross-capacitor C p3 The output capacitor C2 charges the battery B2, the output capacitor C3 charges the battery B3, and the output capacitor C4 charges the battery B4.

[0048] The principle of battery balancing is to keep each battery cell in a series-connected battery pack in a balanced state. Currently, the balance of the entire battery pack is mainly determined by whether the terminal voltage of the battery cell is balanced.

[0049] When the switch S is turned on, there is a loop C1→B1. According to the KVL theorem, we know that u B1 =u C1 ; There is a loop C p1 →S→D p1 →C2, C2→B2, according to the KVL theorem, we know that the cross-over capacitor C p1 The voltage u Cp1 Equal to the voltage u of the output capacitor C2 C2 , which is also equal to the voltage u of battery B2 B2 , that is u B2 =u C2 =u Cp1 ; There is a loop C p1 →D p1 →C3→D p2 →C p2 , C3→B3, KVL theorem shows that u B3 =u C3 =u Cp2 -u Cp1 ; There is a loop C p2 →D p2 →C4→Dp3 →C p3 , C4→B4, KVL theorem shows that u B4 =u C4 =u Cp3 -u Cp2 .

[0050] When switch S is turned off, there is a loop C p1 →D1→C1→D2, C1→B1. According to the KVL theorem, the voltage of the output capacitor C1 is equal to the voltage of the cross-capacitor C p1 The voltage, that is, u B1 =u C1 =u Cp1 ; There is a loop C p2 →C p1 →D2→C2→D3, C2→B2, according to the KVL theorem, that is, u B2 =u C2 =u Cp2 -u Cp1 ; There is a loop C p3 →C p2 →D3→C3→D4, C3→B3, according to the KVL theorem, that is, u B3 =u C3 =u Cp3 -u Cp2 ; There is a loop C4→B4. From the KVL theorem, we know that u B4 =u C4 .

[0051] During the entire switching cycle, according to the capacitance ampere-second balance principle and the above analysis, the cross-connected capacitor C p1 The voltage is equal to 1 times the voltage of battery B1, that is, u Cp1 =u B1 ; Cross-connect capacitor C p2 The voltage is equal to twice the voltage of battery B1, that is, u Cp2 =2*u B1 ; Cross-connect capacitor C p3 The voltage is equal to 3 times the voltage of battery B1, that is, u Cp3 =3*u B1 . At the same time, there is u B1 =u B2 =u B3 =u B4 , that is, the voltage of each battery cell is equal, achieving the balance of the battery pack.

[0052] The present invention provides an active balancing circuit for a series battery pack based on a Boost converter, and the technical effects are as follows:

[0053] 1) The active balancing circuit of the present invention can effectively reduce the terminal voltage imbalance problem caused by the cross regulation rate in the multi-output boost converter, reduce the voltage deviation, and improve the battery balancing accuracy.

[0054] 2) The active balancing circuit of the present invention is simple to control and realizes automatic voltage balancing between battery cells through cross-connected capacitors without the need for complex sampling and control algorithms. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0056] Figure 1 It is the circuit principle diagram of the present invention;

[0057] Figure 2 The circuit schematic diagram of the present invention is to realize the balancing of a battery pack with four battery units connected in series.

[0058] Figure 3 This is a simulation diagram of the present invention realizing balancing of a battery pack with four battery cells connected in series. DETAILED DESCRIPTION

[0059] like Figure 2 As shown, an active balancing circuit based on a Boost converter with four single batteries connected in series, the balancing circuit includes:

[0060] A 4-way output boost converter, 3 jumper capacitors and 4 battery cells;

[0061] The 4-way output boost converter includes an inductor L, a power switch S, a first output diode D1, and a first output capacitor C1;

[0062] The second output diode D2, the second output capacitor C2, the first jumper capacitor C p1 , the first clamping diode D p1 ;

[0063] The third output transistor D2, the third output capacitor C3, the second jumper capacitor C p2 , the second clamping diode D p2 ;

[0064] The fourth output transistor D4, the fourth output capacitor C4, the third jumper capacitor C p3 , the third clamping diode D p3 ;

[0065] One end of the inductor L is connected to the cathode of the output diode D1, one end of the first output capacitor C1, and the positive electrode of the battery B1.

[0066] The other end of the inductor L is connected to the drain of the switch S and the positive electrode of the output diode D1 respectively, and the negative electrode of the battery B1 is connected to the other end of the first output capacitor C1 and the source of the switch S respectively;

[0067] Among the 3 jumper capacitors,

[0068] The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the second output diode D2 is connected to one end of the second output capacitor C2 and the positive electrode of the battery B2, and the negative electrode of the battery B2 is connected to the other end of the second output capacitor C2 and the first clamping diode D p1 anode;

[0069] The second bridge capacitor C p2 The other end is connected to the second clamping diode D p2 The cathode of the third output diode D2 is connected to one end of the third output capacitor C3 and the positive electrode of the battery B3 respectively, and the negative electrode of the battery B3 is connected to the other end of the third output capacitor C3 and the second clamping diode D p2 anode;

[0070] The third bridge capacitor C p3 The other end is connected to the third clamping diode D p3 The cathode of the fourth output diode D4 is connected to one end of the fourth output capacitor C4 and the positive electrode of the battery B4 respectively, and the negative electrode of the battery B4 is connected to the other end of the fourth output capacitor C4 and the third clamping diode D p3 anode;

[0071] The anode of the first output diode D1 is connected to the first jumper capacitor C p1 One end, the second cross-connect capacitor C p2 One end, the third way cross-connect capacitor C p3 one end;

[0072] The other end of the first output capacitor C1 is connected to one end of the second output capacitor C2;

[0073] The other end of the second output capacitor C2 is connected to one end of the third output capacitor C3;

[0074] The other end of the third output capacitor C3 is connected to one end of the fourth output capacitor C4;

[0075] The other end of the fourth output capacitor C4 is connected to the source of the switch S.

[0076] The gate of the power switch S is connected to a controller whose duty cycle can be varied between 0 and 1.

[0077] When the power switch S is turned on, the clamping diode D p1 , clamping diode D p2 and clamping diode D p3 The first output diode D1, the second output diode D2, the third output diode D3 and the fourth output diode D4 are turned off. The power supply charges the energy storage inductor L, and the current of the inductor L increases. The output capacitor C1 charges the battery B1, and the cross-connected capacitor C p1 To charge the output capacitor C2 and battery B2, the capacitor C p2 To charge the output capacitor C3 and battery B3, the cross-capacitor C p3 Charge the output capacitor C4 and the battery B4.

[0078] When the power switch S is turned off, the clamping diode D p1 , clamping diode D p2 and clamping diode D p3 The first output diode D1, the second output diode D2, the third output diode D3 are turned off, and the fourth output diode D4 is turned on. The power supply and the energy storage inductor L jointly supply the output capacitor C1, the battery B1, and the jumper capacitor C p1 , cross-capacitor C p2 , cross-capacitor C p3 The output capacitor C2 charges the battery B2, the output capacitor C3 charges the battery B3, and the output capacitor C4 charges the battery B4.

[0079] The principle of battery balancing is to keep each battery cell in a series-connected battery pack in a balanced state. Currently, the balance of the entire battery pack is mainly determined by whether the terminal voltage of the battery cell is balanced.

[0080] When the switch S is turned on, there is a loop C1→B1. According to the KVL theorem, we know that u B1 =u C1 ; There is a loop C p1 →S→D p1 →C2, C2→B2, according to the KVL theorem, we know that the cross-over capacitor C p1 The voltage u Cp1 Equal to the voltage u of the output capacitor C2 C2 , which is also equal to the voltage u of battery B2 B2 , that is u B2 =u C2 =u Cp1 ; There is a loop C p1 →D p1 →C3→D p2 →C p2 , C3→B3, KVL theorem shows that u B3 =uC3 =u Cp2 -u Cp1 ; There is a loop C p2 →D p2 →C4→D p3 →C p3 , C4→B4, KVL theorem shows that u B4 =u C4 =u Cp3 -u Cp2 .

[0081] When switch S is turned off, there is a loop C p1 →D1→C1→ D2 , C1→B1, according to the KVL theorem, the voltage of the output capacitor C1 is equal to the voltage across the capacitor C p1 The voltage, that is, u C1 =u Cp1 ; There is a loop C p2 →C p1 →D2→C2→D3, C2→B2, according to the KVL theorem, that is, u B2 =u C2 =u Cp2 -u Cp1 ; There is a loop C p3 →C p2 →D3→C3→D4, C3→B3, according to the KVL theorem, that is, u B3 =u C3 =u Cp3 -u Cp2 ; There is a loop C4→B4. From the KVL theorem, we know that u B4 =u C4 .

[0082] During the entire switching cycle, according to the capacitance ampere-second balance principle and the above analysis, the cross-connected capacitor C p1 The voltage is equal to 1 times the voltage of battery B1, that is, u Cp1 =u B1 ; Cross-connect capacitor C p2 The voltage is equal to twice the voltage of battery B1, that is, u Cp2 =2*u B1 ; Cross-connect capacitor C p3 The voltage is equal to 3 times the voltage of battery B1, that is, u Cp3 =3*uB1. Then we have u B1 =u B2 =u B3 =u B4 , that is, the voltage of each battery cell is equal, achieving the balance of the battery pack.

[0083] Figure 3This is a simulation diagram of the present invention to achieve balancing of a battery pack with four battery cells in series. Figure 3 It can be seen that when charging multiple groups of batteries, due to the different initial state of charge (SOC) of each battery, under the action of the balanced topology, the charging rate of each battery is different, and as the charging progresses, the SOC of each group of batteries continues to converge and quickly reaches a relatively stable and close SOC value, indicating that the topology has a good balanced charging effect and a fast speed.

[0084] Compared with the traditional multi-channel series balancing structure, the present invention realizes automatic voltage balancing between battery cells through jumper capacitors, does not require complex sampling and control algorithms, and avoids the terminal voltage imbalance problem caused by the cross-regulation rate of the transformer when multiple windings are output, effectively reduces voltage deviation, and improves battery balancing accuracy.

Claims

1. Active balancing circuit of series battery pack based on Boost converter, characterized by The equalization circuit includes: An n-output boost converter, n-1 cross-capacitors and n battery cells; The n-channel output boost converter includes an inductor L, a power switch S, a first channel output diode D1, and a first channel output capacitor C1; The second output diode D2, the second output capacitor C2, the first jumper capacitor C p1 , the first clamping diode D p1 ; The third output transistor D2, the third output capacitor C3, the second jumper capacitor C p2 , the second clamping diode D p2 ; ... and so on. The nth output diode D n , the nth output capacitor C n , the n-1th cross-connect capacitor C p(n-1) , the n-1th clamping diode D p(n-1) ; One end of the inductor L is connected to the cathode of the output diode D1, one end of the first output capacitor C1, and the positive electrode of the battery B1. The other end of the inductor L is connected to the drain of the switch S and the positive electrode of the output diode D1 respectively, and the negative electrode of the battery B1 is connected to the other end of the first output capacitor C1 and the source of the switch S respectively; Among the n-1 jumper capacitors, The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the second output diode D2 is connected to one end of the second output capacitor C2 and the positive electrode of the battery B2, and the negative electrode of the battery B2 is connected to the other end of the second output capacitor C2 and the first clamping diode D p1 anode; The second bridge capacitor C p2 The other end is connected to the second clamping diode D p2 The cathode of the third output diode D2 is connected to one end of the third output capacitor C3 and the positive electrode of the battery B3 respectively, and the negative electrode of the battery B3 is connected to the other end of the third output capacitor C3 and the second clamping diode D p2 anode; The third bridge capacitor C p3 The other end is connected to the third clamping diode D p3 The cathode of the fourth output diode D4 is connected to one end of the fourth output capacitor C4 and the positive electrode of the battery B4 respectively, and the negative electrode of the battery B4 is connected to the other end of the fourth output capacitor C4 and the third clamping diode D p3 anode; ... and so on. The n-1th cross-connect capacitor C p(n-1) The other end is connected to the n-1th clamping diode D p(n-1) Cathode, nth output diode D n Anode, nth output diode D n The cathode is connected to the nth output capacitor C n One end, battery B n Positive electrode, battery B n The negative electrode is connected to the nth output capacitor C n The other end, the n-1th clamping diode D p(n-1) anode; The anode of the first output diode D1 is connected to the first jumper capacitor C p1 One end, the second cross-connect capacitor C p2 One end, the third way cross-connect capacitor C p3 One end, ... and so on, the n-1th path is connected across the capacitor C p(n-1) one end; The other end of the first output capacitor C1 is connected to one end of the second output capacitor C2; The other end of the second output capacitor C2 is connected to one end of the third output capacitor C3; The other end of the third output capacitor C3 is connected to one end of the fourth output capacitor C4; ... and so on. Output capacitor C of the n-1th channel n-1 The other end is connected to the nth output capacitor C n one end; The nth output capacitor C n The other end is connected to the source of switch S.

2. The active balancing circuit of series-connected battery packs based on a Boost converter according to claim 1, characterized in that: The gate of the power switch S is connected to a controller, and its duty cycle can be changed between 0 and 1.

3. An active balancing circuit based on a Boost converter with four single batteries connected in series, characterized in that: The equalization circuit includes: A 4-way output boost converter, 3 jumper capacitors and 4 battery cells; The 4-way output boost converter includes an inductor L, a power switch S, a first output diode D1, and a first output capacitor C1; The second output diode D2, the second output capacitor C2, the first jumper capacitor C p1 , the first clamping diode D p1 ; The third output transistor D2, the third output capacitor C3, the second jumper capacitor C p2 , the second clamping diode D p2 ; The fourth output transistor D4, the fourth output capacitor C4, the third jumper capacitor C p3 , the third clamping diode D p3 ; One end of the inductor L is connected to the cathode of the output diode D1, one end of the first output capacitor C1, and the positive electrode of the battery B1. The other end of the inductor L is connected to the drain of the switch S and the positive electrode of the output diode D1 respectively, and the negative electrode of the battery B1 is connected to the other end of the first output capacitor C1 and the source of the switch S respectively; Among the 3 jumper capacitors, The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the second output diode D2 is connected to one end of the second output capacitor C2 and the positive electrode of the battery B2, and the negative electrode of the battery B2 is connected to the other end of the second output capacitor C2 and the first clamping diode D p1 anode; The second bridge capacitor C p2 The other end is connected to the second clamping diode D p2 The cathode of the third output diode D2 is connected to one end of the third output capacitor C3 and the positive electrode of the battery B3 respectively, and the negative electrode of the battery B3 is connected to the other end of the third output capacitor C3 and the second clamping diode D p2 anode; The third bridge capacitor C p3 The other end is connected to the third clamping diode D p3 The cathode of the fourth output diode D4 is connected to one end of the fourth output capacitor C4 and the positive electrode of the battery B4 respectively, and the negative electrode of the battery B4 is connected to the other end of the fourth output capacitor C4 and the third clamping diode D p3 anode; The anode of the first output diode D1 is connected to the first jumper capacitor C p1 One end, the second cross-connect capacitor C p2 One end, the third way cross-connect capacitor C p3 one end; The other end of the first output capacitor C1 is connected to one end of the second output capacitor C2; The other end of the second output capacitor C2 is connected to one end of the third output capacitor C3; The other end of the third output capacitor C3 is connected to one end of the fourth output capacitor C4; The other end of the fourth output capacitor C4 is connected to the source of the switch S.

4. According to claim 3, a Boost converter-based active balancing circuit comprising four single cells connected in series, characterized in that: When the power switch S is turned on, the clamping diode D p1 , clamping diode D p2 and clamping diode D p3 The first output diode D1, the second output diode D2, the third output diode D3 and the fourth output diode D4 are turned off; the power supply charges the energy storage inductor L, and the current of the inductor L increases; the output capacitor C1 charges the battery B1, and the jumper capacitor C p1 To charge the output capacitor C2 and battery B2, the capacitor C p2 To charge the output capacitor C3 and battery B3, the cross-capacitor C p3 Charge the output capacitor C4 and battery B4; When the power switch S is turned off, the clamping diode D p1 , clamping diode D p2 and clamping diode D p3 The first output diode D1, the second output diode D2, the third output diode D3 are turned off, and the fourth output diode D4 is turned on; the power supply and the energy storage inductor L jointly supply the output capacitor C1, the battery B1, and the jumper capacitor C p1 , cross-capacitor C p2 , cross-capacitor C p3 Charging; output capacitor C2 charges battery B2, output capacitor C3 charges battery B3, and output capacitor C4 charges battery B4.

5. According to claim 3, a Boost converter-based active balancing circuit comprising four single batteries connected in series, characterized in that: When the switch S is turned on, there is a loop C1→B1. According to the KVL theorem, we know that u B1 =u C1 ; There is a loop C p1 →S→D p1 →C2, C2→B2, according to the KVL theorem, we know that the cross-over capacitor C p1 The voltage u Cp1 Equal to the voltage u of the output capacitor C2 C2 , which is also equal to the voltage u of battery B2 B2 , that is u B2 =u C2 =u Cp1 ; There is a loop C p1 →D p1 →C3→D p2 →C p2 , C3→B3, KVL theorem shows that u B3 =u C3 =u Cp2 -u Cp1 ; There is a loop C p2 →D p2 →C4→D p3 →C p3 , C4→B4, KVL theorem shows that u B4 =u C4 =u Cp3 -u Cp2 ; When switch S is turned off, there is a loop C p1 →D1→C1→D2, C1→B1. According to the KVL theorem, the voltage of the output capacitor C1 is equal to the voltage of the cross-capacitor C p1 The voltage, that is, u B1 =u C1 =u Cp1 ; There is a loop C p2 →C p1 →D2→C2→D3, C2→B2, according to the KVL theorem, that is, u B2 =u C2 =u Cp2 -u Cp1 ; There is a loop C p3 →C p2 →D3→C3→D4, C3→B3, according to the KVL theorem, that is, u B3 =u C3 =u Cp3 -u Cp2 ; There is a loop C4→B4. From the KVL theorem, we know that u B4 =u C4 ; During the entire switching cycle, according to the capacitance ampere-second balance principle and the above analysis, the cross-connected capacitor C p1 The voltage is equal to 1 times the voltage of battery B1, that is, u Cp1 =u B1 ; Cross-connect capacitor C p2 The voltage is equal to twice the voltage of battery B1, that is, u Cp2 =2*u B1 ; Cross-connect capacitor C p3 The voltage is equal to 3 times the voltage of battery B1, that is, u Cp3 =3*u B1 ; At the same time, there is u B1 =u B2 =u B3 =u B4 , that is, the voltage of each battery cell is equal, achieving the balance of the battery pack.

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