Series battery pack active equalization circuit based on Zeta converter

Abstract

The invention discloses a series battery pack active equalization circuit based on a Zeta converter. The equalization circuit comprises an n-path output zeta converter, n bridging capacitors and n battery units, the n-path output zeta converter comprises an inductor L, a power switch S, a first-path output diode D1, a first-path output capacitor C1, a first-path bridging capacitor Cp1 and a first-path clamping diode Dp1, a second path of output diode D2, a second path of output capacitor C2, a second path of bridging capacitor Cp2 and a second path of clamping diode Dp2; a third-path output diode D3, a third-path output capacitor C3, a third-path bridging capacitor Cp3 and a third-path clamping diode Dp3; and the like, an nth output diode Dn, an nth output capacitor Cn, an nth bridging capacitor Cpn and an nth clamping diode Dpn. 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 equalization circuit, and in particular to an active equalization circuit for a series battery pack based on a Zeta 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 resistors, 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 patent CN113489083A. 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 levels 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.

[0004] However, the complexity of this method lies in its balancing circuit design, which involves sophisticated logic control of multiple control switches, which undoubtedly increases the difficulty of technical implementation. Summary of the invention

[0005] 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 Zeta converter, which is composed of a multi-channel output converter and a plurality of cross-over capacitors. The active balancing circuit is based on the zeta circuit and adopts a multi-output zeta circuit topology structure. By adding a cross-over capacitor between each output, the terminal voltage of the battery cells inside the battery pack is balanced (same). Compared with the traditional multi-series zeta circuit balancing structure, 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 zeta circuit outputs, effectively reducing voltage deviation and improving battery balancing accuracy.

[0006] The technical solution adopted by the present invention is:

[0007] The active balancing circuit of a series battery pack based on a Zeta converter comprises:

[0008] An n-output zeta converter, n cross-capacitors and n battery cells;

[0009] The n-way output zeta converter includes an inductor L, a power switch S, and:

[0010] The first output diode D1, the first output capacitor C1, the first jumper capacitor C p1 , the first clamping diode D p1 ;

[0011] The second output diode D2, the second output capacitor C2, the second jumper capacitor C p2 , the second clamping diode D p2 ;

[0012] The third output diode D3, the third output capacitor C3, the third jumper capacitor C p3 , the third clamping diode D p3 ;

[0013] ... and so on.

[0014] The nth output diode D n , the nth output capacitor C n , the nth bridge capacitor C pn , the nth clamping diode D pn ;

[0015] The drain of switch S is connected to the cathode of output diode D1 and one end of output capacitor C1 respectively; the source of switch S is connected to one end of inductor L and the first bridge capacitor C1 respectively. p1 One end,

[0016] The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the output diode D1 is connected to one end of the output capacitor C1 and the positive electrode of the lithium battery B1. The negative electrode of the lithium battery B1 is connected to the other end of the output capacitor C1 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 output diode D2 is connected to one end of the output capacitor C2 and the positive electrode of the lithium battery B2. The negative electrode of the lithium battery B2 is connected to the other end of the output capacitor C2 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 output diode D3 is connected to one end of the output capacitor C3 and the positive electrode of the lithium battery B3. The negative electrode of the lithium battery B3 is connected to the other end of the output capacitor C3 and the third clamping diode D p3 anode;

[0019] ... and so on.

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

[0021] The first bridge capacitor C p1 One end is connected to the second bridge capacitor C p2 One end, the third way cross-connect capacitor C p3 One end, ... and so on, the nth path is connected across the capacitor C pn one end;

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

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

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

[0025] ... and so on.

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

[0027] The drain of switch S is connected to the positive electrode of lithium battery B1, and the other end of inductor L is connected to lithium battery B n negative electrode.

[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 for a battery pack of four single cells connected in series in a Zeta converter includes:

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

[0031] The n-way output zeta converter includes an inductor L, a power switch S, and:

[0032] The first output diode D1, the first output capacitor C1, the first jumper capacitor C p1 , the first clamping diode D p1 ;

[0033] The second output diode D2, the second output capacitor C2, the second jumper capacitor C p2 , the second clamping diode D p2 ;

[0034] The third output diode D3, the third output capacitor C3, the third jumper capacitor C p3 , the third clamping diode D p3 ;

[0035] The fourth output diode D4, the fourth output capacitor C4, the fourth jumper capacitor C p4 , the fourth clamping diode D p4 ;

[0036] The drain of switch S is connected to the cathode of output diode D1 and one end of output capacitor C1 respectively; the source of switch S is connected to one end of inductor L and the first bridge capacitor C1 respectively. p1 One end,

[0037] The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1The cathode of the output diode D1 is connected to one end of the output capacitor C1 and the positive electrode of the lithium battery B1. The negative electrode of the lithium battery B1 is connected to the other end of the output capacitor C1 and the first clamping diode D p1 anode;

[0038] The second bridge capacitor C p2 The other end is connected to the second clamping diode D p2 The cathode of the output diode D2 is connected to one end of the output capacitor C2 and the positive electrode of the lithium battery B2. The negative electrode of the lithium battery B2 is connected to the other end of the output capacitor C2 and the second clamping diode D p2 anode;

[0039] The third bridge capacitor C p3 The other end is connected to the third clamping diode D p3 The cathode of the output diode D3 is connected to one end of the output capacitor C3 and the positive electrode of the lithium battery B3. The negative electrode of the lithium battery B3 is connected to the other end of the output capacitor C3 and the third clamping diode D p3 anode;

[0040] The fourth bridge capacitor C p4 The other end is connected to the fourth clamping diode D p4 The cathode of the output diode D4 is connected to one end of the output capacitor C4 and the positive electrode of the lithium battery B4. The negative electrode of the lithium battery B4 is connected to the other end of the output capacitor C4 and the fourth clamping diode D p4 anode;

[0041] The first bridge capacitor C p1 One end is connected to the second bridge capacitor C p2 One end, the third way cross-connect capacitor C p3 One end, the fourth path crosses the capacitor C p4 one end;

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

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

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

[0045] The drain of the switch S is connected to the positive electrode of the lithium battery B1, and the other end of the inductor L is connected to the negative electrode of the lithium battery B4.

[0046] Take a battery pack consisting of four single batteries B1, B2, B3, and B4 connected in series as an example. When the power switch S is turned on, the first output diode D1, the second output diode D2, the third output diode D3, and the fourth output diode D4 are turned on, and the clamping diode D p1 , clamping diode D p2 , clamping diode D p3 and clamping diode D p4 Turn off. The power supply is supplied to the energy storage inductor L and the cross-connected capacitor C p2 , cross-capacitor C p3 and the cross-over capacitor C p4 Charge. The cross-capacitor C p1 The output capacitor C1 and the lithium battery B1 are charged. The output capacitor C2 charges the lithium battery B2, the output capacitor C3 charges the lithium battery B3, and the output capacitor C4 charges the lithium battery B4.

[0047] 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 off, the clamping diode D p1 , clamping diode D p2 , clamping diode D p3 and clamping diode D p4 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 energy storage inductor L gives the jumper capacitor C p1 Charging; cross-capacitor C p2 Charge the output capacitor C2 and lithium battery B2; connect the capacitor C p3 Charge the output capacitor C3 and lithium battery B3; connect the capacitor C p4 Charge the output capacitor C4 and the lithium battery B4.

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

[0049] When switch S is turned on, there is a loop C1→B1, C p1 →D1→C1→D2→C p2 , from the KVL theorem we know that u B1 =u C1 =u Cp2 -u Cp1 ; There is a loop C p2 →D2→C2→D3→C p3 , C2→B2, from KVL theorem we know that u B2 =u C2 =u Cp3-uCp2; there is a loop; there is a loop Cp3→D3→C3→D4→Cp4, C3→B3, from the KVL theorem we know that u B3 =u C3 =u Cp4 -u Cp3 ; There is a loop C4→B4. From the KVL theorem, we know that u B4 =u C4 .

[0050] When the switch S is turned off, there is a loop C1→B1. According to the KVL theorem, the voltage of the lithium battery B1 is equal to the voltage of the output capacitor C1, that is, u B1 =u C1 ; There is a loop C p1 →D p1 →C2→D p2 →C p2 , C2→B2, from KVL theorem we know that u B2 =u C2 =u Cp2 -u Cp1 ; There is a loop C p2 →D p2 →C3→D p3 →C p3 , C3→B3, from KVL theorem we know that u B3 =u C3 =u Cp3 -u Cp2 ; There is a loop C p3 →D p3 →C4→D p4 →C p4 , C4→B4, from KVL theorem we know that uB4=uC4=uC p 4-uC p 3.

[0051] During the entire switching cycle, according to the capacitance ampere-second balance principle and the above analysis, the voltage of lithium battery B1 is equal to the voltage of lithium battery B2, equal to the voltage of lithium battery B3, and equal to the voltage of lithium battery B4, that is, u B1 =u B2 =u B3 =u B4 , the voltage of each lithium battery cell is equal, achieving the balance of the lithium battery pack.

[0052] The present invention provides an active balancing circuit for a series battery pack based on a Zeta 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 zeta 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] The present invention will be further described in detail below in conjunction with the accompanying drawings. Figure 2 As shown, the present invention is a battery pack active balancing circuit containing 4 battery cells, the circuit includes a 4-way output zeta converter, 4 cross-connected capacitors and 4 battery cells, wherein:

[0060] The n-way output zeta converter includes an inductor L, a power switch S, and:

[0061] The first output diode D1, the first output capacitor C1, the first jumper capacitor C p1 , the first clamping diode D p1 ;

[0062] The second output diode D2, the second output capacitor C2, the second jumper capacitor C p2 , the second clamping diode D p2 ;

[0063] The third output diode D3, the third output capacitor C3, the third jumper capacitor C p3 , the third clamping diode D p3 ;

[0064] The fourth output diode D4, the fourth output capacitor C4, the fourth jumper capacitor C p4 , the fourth clamping diode D p4 ;

[0065] The drain of switch S is connected to the cathode of output diode D1 and one end of output capacitor C1 respectively; the source of switch S is connected to one end of inductor L and the first bridge capacitor C1 respectively. p1 One end,

[0066] The first bridge capacitor Cp1 The other end is connected to the first clamping diode D p1 The cathode of the output diode D1 is connected to one end of the output capacitor C1 and the positive electrode of the lithium battery B1. The negative electrode of the lithium battery B1 is connected to the other end of the output capacitor C1 and the first clamping diode D p1 anode;

[0067] The second bridge capacitor C p2 The other end is connected to the second clamping diode D p2 The cathode of the output diode D2 is connected to one end of the output capacitor C2 and the positive electrode of the lithium battery B2. The negative electrode of the lithium battery B2 is connected to the other end of the output capacitor C2 and the second clamping diode D p2 anode;

[0068] The third bridge capacitor C p3 The other end is connected to the third clamping diode D p3 The cathode of the output diode D3 is connected to one end of the output capacitor C3 and the positive electrode of the lithium battery B3. The negative electrode of the lithium battery B3 is connected to the other end of the output capacitor C3 and the third clamping diode D p3 anode;

[0069] The fourth bridge capacitor C p4 The other end is connected to the fourth clamping diode D p4 The cathode of the output diode D4 is connected to one end of the output capacitor C4 and the positive electrode of the lithium battery B4. The negative electrode of the lithium battery B4 is connected to the other end of the output capacitor C4 and the fourth clamping diode D p4 anode;

[0070] The first bridge capacitor C p1 One end is connected to the second bridge capacitor C p2 One end, the third way cross-connect capacitor C p3 One end, the fourth path crosses the capacitor C p4 one end;

[0071] The other end of the output capacitor C1 is connected to one end of the output capacitor C2;

[0072] The other end of the output capacitor C2 is connected to one end of the output capacitor C3;

[0073] The other end of the output capacitor C3 is connected to one end of the output capacitor C4;

[0074] The drain of the switch S is connected to the positive electrode of the lithium battery B1, and the other end of the inductor L is connected to the negative electrode of the lithium battery B4.

[0075] When the power switch S is turned on, the first output diode D1, the second output diode D2, the third output diode D3 and the fourth output diode D4 are turned on, and the clamping diode D p1 , clamping diode D p2 , clamping diode D p3 and clamping diode D p4 Turn off. The power supply is supplied to the energy storage inductor L and the cross-connected capacitor C p2 , cross-capacitor C p3 and the cross-over capacitor C p4 Charge. The cross-capacitor C p1 The output capacitor C1 and the lithium battery B1 are charged. The output capacitor C2 charges the lithium battery B2, the output capacitor C3 charges the lithium battery B3, and the output capacitor C4 charges the lithium battery B4.

[0076] When the power switch S is turned off, the clamping diode D p1 , clamping diode D p2 , clamping diode D p3 and clamping diode D p4 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 energy storage inductor L gives the jumper capacitor C p1 Charging; cross-capacitor C p2 Charge the output capacitor C2 and lithium battery B2; connect the capacitor C p3 Charge the output capacitor C3 and lithium battery B3; connect the capacitor C p4 Charge the output capacitor C4 and the lithium battery B4.

[0077] The principle of battery balancing is to keep the lithium battery cells in the series battery pack in a balanced state. Currently, the balance of the entire lithium battery pack is mainly determined by whether the terminal voltage of the lithium battery cells is balanced.

[0078] When switch S is turned on, there is a loop C1→B1, C p1 →D1→C1→D2→C p2 , from the KVL theorem we know that u B1 =u C1 =u Cp2 -u Cp1 ; There is a loop C p2 →D2→C2→D3→C p3 , C2→B2, from KVL theorem we know that u B2 =u C2 =u Cp3 -uCp2; there is a loop; there is a loop Cp3→D3→C3→D4→Cp4, C3→B3, from the KVL theorem we know that u B3 =uC3 =u Cp4 -u Cp3 ; There is a loop C4→B4. From the KVL theorem, we know that u B4 =u C4 .

[0079] When the switch S is turned off, there is a loop C1→B1. According to the KVL theorem, the voltage of the lithium battery B1 is equal to the voltage of the output capacitor C1, that is, u B1 =u C1 ; There is a loop C p1 →D p1 →C2→D p2 →C p2 , C2→B2, from KVL theorem we know that u B2 =u C2 =u Cp2 -u Cp1 ; There is a loop C p2 →D p2 →C3→D p3 →C p3 , C3→B3, from KVL theorem we know that u B3 =u C3 =u Cp3 -u Cp2 ; There is a loop C p3 →D p3 →C4→D p4 →C p4 , C4→B4, from KVL theorem we know that uB4=uC4=uC p 4-uC p 3.

[0080] During the entire switching cycle, according to the capacitance ampere-second balance principle and the above analysis, the voltage of lithium battery B1 is equal to the voltage of lithium battery B2, equal to the voltage of lithium battery B3, and equal to the voltage of lithium battery B4, that is, u B1 =u B2 =u B3 =u B4 , the voltage of each lithium battery cell is equal, achieving the balance of the lithium battery pack.

[0081] Figure 3 This 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 battery continues to converge and soon reaches a relatively stable and close SOC value, indicating that the topology has a good balanced charging effect and a fast speed.

[0082] 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 for series connected battery pack based on Zeta converter, characterized in that The equalization circuit includes: An n-output zeta converter, n cross-capacitors and n battery cells; The n-way output zeta converter includes an inductor L, a power switch S, and: The first output diode D1, the first output capacitor C1, the first jumper capacitor C p1 , the first clamping diode D p1 ; The second output diode D2, the second output capacitor C2, the second jumper capacitor C p2 , the second clamping diode D p2 ; The third output diode D3, the third output capacitor C3, the third jumper capacitor C p3 , the third clamping diode D p3 ; ... and so on. The nth output diode D n , the nth output capacitor C n , the nth cross-connect capacitor C pn , the nth clamping diode D pn ; The drain of switch S is connected to the cathode of output diode D1 and one end of output capacitor C1 respectively; the source of switch S is connected to one end of inductor L and the first bridge capacitor C1 respectively. p1 One end, The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the output diode D1 is connected to one end of the output capacitor C1 and the positive electrode of the lithium battery B1. The negative electrode of the lithium battery B1 is connected to the other end of the output capacitor C1 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 output diode D2 is connected to one end of the output capacitor C2 and the positive electrode of the lithium battery B2. The negative electrode of the lithium battery B2 is connected to the other end of the output capacitor C2 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 output diode D3 is connected to one end of the output capacitor C3 and the positive electrode of the lithium battery B3. The negative electrode of the lithium battery B3 is connected to the other end of the output capacitor C3 and the third clamping diode D p3 anode; ... and so on. The nth cross-connect capacitor C pn The other end is connected to the nth clamping diode D pn Cathode, output diode D n Anode, output diode D n The cathode is connected to the output capacitor C n One end, lithium battery B n Positive electrode, lithium battery B n The negative pole is connected to the output capacitor C n The other end, the nth clamping diode D pn anode; The first bridge capacitor C p1 One end is connected to the second bridge capacitor C p2 One end, the third way cross-connect capacitor C p3 One end, ... and so on, the nth path is connected across the capacitor C pn one end; The other end of the output capacitor C1 is connected to one end of the output capacitor C2; The other end of the output capacitor C2 is connected to one end of the output capacitor C3; The other end of the output capacitor C3 is connected to one end of the output capacitor C4; ... and so on. Output capacitor C n-1 The other end is connected to the output capacitor C n one end; The drain of switch S is connected to the positive electrode of lithium battery B1, and the other end of inductor L is connected to lithium battery B n negative electrode.

2. The active balancing circuit for series-connected battery packs based on a Zeta 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 for a battery pack of four single cells connected in series based on a Zeta converter, characterized in that: The equalization circuit includes: A 4-way output zeta converter, 4 jumper capacitors and 4 battery cells; The n-way output zeta converter includes an inductor L, a power switch S, and: The first output diode D1, the first output capacitor C1, the first jumper capacitor C p1 , the first clamping diode D p1 ; The second output diode D2, the second output capacitor C2, the second jumper capacitor C p2 , the second clamping diode D p2 ; The third output diode D3, the third output capacitor C3, the third jumper capacitor C p3 , the third clamping diode D p3 ; The fourth output diode D4, the fourth output capacitor C4, the fourth jumper capacitor C p4 , the fourth clamping diode D p4 ; The drain of switch S is connected to the cathode of output diode D1 and one end of output capacitor C1 respectively; the source of switch S is connected to one end of inductor L and the first bridge capacitor C1 respectively. p1 One end, The first bridge capacitor C p1 The other end is connected to the first clamping diode D p1 The cathode of the output diode D1 is connected to one end of the output capacitor C1 and the positive electrode of the lithium battery B1. The negative electrode of the lithium battery B1 is connected to the other end of the output capacitor C1 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 output diode D2 is connected to one end of the output capacitor C2 and the positive electrode of the lithium battery B2. The negative electrode of the lithium battery B2 is connected to the other end of the output capacitor C2 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 output diode D3 is connected to one end of the output capacitor C3 and the positive electrode of the lithium battery B3. The negative electrode of the lithium battery B3 is connected to the other end of the output capacitor C3 and the third clamping diode D p3 anode; The fourth bridge capacitor C p4 The other end is connected to the fourth clamping diode D p4 The cathode of the output diode D4 is connected to one end of the output capacitor C4 and the positive electrode of the lithium battery B4. The negative electrode of the lithium battery B4 is connected to the other end of the output capacitor C4 and the fourth clamping diode D p4 anode; The first bridge capacitor C p1 One end is connected to the second bridge capacitor C p2 One end, the third way cross-connect capacitor C p3 One end, the fourth cross-connect capacitor C p4 one end; The other end of the output capacitor C1 is connected to one end of the output capacitor C2; The other end of the output capacitor C2 is connected to one end of the output capacitor C3; The other end of the output capacitor C3 is connected to one end of the output capacitor C4; The drain of the switch S is connected to the positive electrode of the lithium battery B1, and the other end of the inductor L is connected to the negative electrode of the lithium battery B4.

4. The active balancing circuit of a battery pack of four single cells connected in series based on a Zeta converter according to claim 3 is characterized in that: When the power switch S is turned on, the first output diode D1, the second output diode D2, the third output diode D3 and the fourth output diode D4 are turned on, and the clamping diode D p1 , clamping diode D p2 , clamping diode D p3 and clamping diode D p4 Turn off; power is supplied to the energy storage inductor L and the cross-connected capacitor C p2 , cross-capacitor C p3 and the cross-over capacitor C p4 Charging; cross-capacitor C p1 The output capacitor C1 and the lithium battery B1 are charged; the output capacitor C2 charges the lithium battery B2, the output capacitor C3 charges the lithium battery B3, and the output capacitor C4 charges the lithium battery B4; When the power switch S is turned off, the clamping diode D p1 , clamping diode D p2 , clamping diode D p3 and clamping diode D p4 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 energy storage inductor L is connected to the jumper capacitor C p1 Charging; cross-capacitor C p2 Charge the output capacitor C2 and lithium battery B2; connect the capacitor C p3 Charge the output capacitor C3 and lithium battery B3; connect the capacitor C p4 Charge the output capacitor C4 and the lithium battery B4.

5. The active balancing circuit of four single-cell series-connected battery pack based on Zeta converter according to claim 3 is characterized in that: When switch S is turned on, there is a loop C1→B1, C p1 →D1→C1→D2→C p2 , from the KVL theorem we know that u B1 =u C1 =u Cp2 -u Cp1 ; There is a loop C p2 →D2→C2→D3→C p3 , C2→B2, from KVL theorem we know that u B2 =u C2 =u Cp3 -uCp2; there is a loop; there is a loop Cp3→D3→C3→D4→Cp4, C3→B3, from the KVL theorem we know that u B3 =u C3 =u Cp4 -u Cp3 ; There is a loop C4→B4. From the KVL theorem, we know that u B4 =u C4 ; When the switch S is turned off, there is a loop C1→B1. According to the KVL theorem, the voltage of the lithium battery B1 is equal to the voltage of the output capacitor C1, that is, u B1 =u C1 ; There is a loop C p1 →D p1 →C2→D p2 →C p2 , C2→B2, from KVL theorem we know that u B2 =u C2 =u Cp2 -u Cp1 ; There is a loop C p2 →D p2 →C3→D p3 →C p3 , C3→B3, from KVL theorem we know that u B3 =u C3 =u Cp3 -u Cp2 ; There is a loop C p3 →D p3 →C4→D p4 →C p4 , C4→B4, from KVL theorem we know that uB4=uC4=uC p 4-uC p 3.

Images