Magnetic Saturation Self-Excited Drive Virtual Parallel Battery Equalization Circuit, System and Method

Abstract

The present invention discloses a magnetic saturation self-excited drive virtual parallel battery equalization circuit, system and method, which relates to the field of battery equalization. The circuit includes: a battery pack composed of n series-connected single-cell battery units, an equalization unit, a self-excited winding, a magnetic reset winding and an external drive signal; each single-cell battery unit includes a single-cell battery and a single-cell battery internal resistance connected in series, and each single-cell battery unit is connected in parallel with an equalization unit. Each equalization unit includes an equalization winding and a switching tube connected in series; the equalization windings are arranged in one-to-one correspondence with the self-excited windings, the same-named ends of each equalization winding and its corresponding self-excited winding are the same, and the same-named ends of the magnetic reset winding and the equalization winding are opposite; the external drive signal drives the switching tube in the first equalization unit starting from the negative electrode of the battery pack; the gate and source of the switching tube in the m-th equalization unit are respectively connected to the positive and negative electrodes of the self-excited winding corresponding to the m-th equalization unit. The present invention simplifies the drive circuit and reduces the cost of the equalization circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of battery equalization, and particularly to a magnetic saturation self-excited drive virtual parallel battery equalization circuit, system and method. Background Art

[0002] With the wide application of various green energy technologies, the energy storage link has become increasingly important. For some time now and in the future, using chemical batteries remains an important way of energy storage. In practical applications, multiple single cells are often connected in series to form a battery pack for use.

[0003] Due to the differences in consistency among each single cell and the differences in temperature, charge and discharge current, etc. during use, after long-term use, the degree of wear of each series-connected battery will vary greatly, resulting in different performances of each single cell, manifested as different voltages. When single cells with inconsistent performances are connected in series, it will lead to inconsistent charge and discharge degrees of each single cell in actual use, resulting in overcharge and over-discharge, seriously affecting the service life and performance of the entire battery pack, and even causing damage to the battery pack.

[0004] To solve the problem of voltage imbalance caused by inconsistent losses of each single cell in the battery pack after long-term use, the existing solution is the battery management system (BMS). This system uses a large number of voltage, current, and temperature sensors to monitor each battery pack in real time. The control unit will formulate a battery equalization plan according to the loss situation of each battery pack, and perform voltage equalization on each battery pack during charging and discharging to make the wear rates of each battery pack tend to be the same, so as to achieve the purpose of voltage equalization. However, the battery equalization system uses a large number of sensors, the circuit is complex, the voltage algorithm for managing and equalizing each single cell is complex, the system calculation and operation cost is high, and a large number of control parameters will lead to a reduction in reliability.

[0005] The virtual parallel battery equalization circuit uses a multi-winding transformer to achieve virtual parallel connection of each single cell. Each single cell corresponds to a winding and a switching tube. The parameters and turns of the windings are the same and are coupled together through a high-frequency magnetic core to achieve the function of automatic voltage equalization. The advantages of a common virtual parallel battery equalization circuit are:

[0006] ① Since each single cell is virtually paralleled, automatic voltage equalization can be achieved without a large number of sensors and complex equalization algorithms.

[0007] ② The virtually paralleled single cells can achieve voltage equalization with large currents.

[0008] ③ Voltage equalization can be achieved in all states of the battery pack, including static, charging, and discharging.

[0009] Disadvantages of a common virtual parallel battery equalization circuit:

[0010] ①A large number of switching tubes require a large number of mutually isolated external drive signals, and a complex isolation drive circuit needs to be designed. The circuit is bulky and costly.

[0011] ②It is difficult to quantitatively analyze and calculate parameters such as the equalizing current of the virtual parallel equalizing circuit. Summary of the Invention

[0012] The object of the present invention is to provide a magnetic saturation self-excited drive virtual parallel battery equalizing circuit, system and method, which simplifies the drive circuit and reduces the cost of the equalizing circuit.

[0013] To achieve the above object, the present invention provides the following solutions:

[0014] A magnetic saturation self-excited drive virtual parallel battery equalizing circuit includes: a battery pack composed of n series-connected single-cell battery units, n equalizing units, n self-excited windings, 1 magnetic reset winding, and an external drive signal; each of the single-cell battery units includes a single-cell battery and a single-cell battery internal resistance connected in series, each of the single-cell battery units is connected in parallel with one of the equalizing units, and each of the equalizing units includes an equalizing winding and a switching tube connected in series; the equalizing windings are arranged in one-to-one correspondence with the self-excited windings, the same-named ends of each of the equalizing windings and each of the self-excited windings are the same, the same-named end of the magnetic reset winding is opposite to that of the equalizing winding, and the magnetic reset winding is connected to the positive pole of the battery pack through a diode; the external drive signal is used to drive the switching tube in the first equalizing unit starting from the negative pole of the battery pack; the gate of the switching tube in the m-th equalizing unit is connected to the positive pole of the self-excited winding corresponding to the m-th equalizing unit, and the source of the switching tube in the m-th equalizing unit is connected to the negative pole of the self-excited winding corresponding to the m-th equalizing unit.

[0015] Optionally, the external drive signal is further used to control the duty cycle of the magnetic saturation self-excited drive virtual parallel battery equalizing circuit by controlling the cut-off time of the switching tube in the first equalizing unit, and the duty cycle is expressed as:

[0016]

[0017]

[0018] where D represents the duty cycle, t on represents the conduction time of the switching tube in the first equalizing unit, t off represents the cut-off time of the switching tube in the first equalizing unit, Ψ s represents the magnetic flux linkage at magnetic saturation, g mdenotes the conductance of the m-th equalization loop formed by the m-th single battery cell and the m-th equalization unit. The resistance of the m-th equalization loop is composed of the internal resistance of the single battery, the internal resistance of the equalization winding, and the internal resistance of the connecting wire in series, E m denotes the voltage of the m-th single battery cell.

[0019] Optionally, the magnetic flux Ψ at magnetic saturation s is expressed as: Ψ s = n 1 B S S;

[0020] where, n 1 denotes the number of turns of each of the equalization windings, B S denotes the magnetic induction intensity at magnetic core saturation, and S denotes the cross-sectional area of the magnetic core.

[0021] Optionally, the number of turns of the magnetic reset winding is

[0022] where, n 1 denotes the number of turns of each of the equalization windings.

[0023] Optionally, the self-excitation winding is sequentially connected in series with a first resistor and a second resistor. The positive electrode of the second resistor is connected to the gate of the corresponding switching transistor, and the negative electrode of the second resistor is connected to the source of the corresponding switching transistor.

[0024] The present invention also discloses a magnetic saturation type self-excitation drive virtual parallel battery equalization system, including the magnetic saturation type self-excitation drive virtual parallel battery equalization circuit described above.

[0025] The present invention also discloses a magnetic saturation type self-excitation drive virtual parallel battery equalization method, which applies the magnetic saturation type self-excitation drive virtual parallel battery equalization circuit described above. The method includes:

[0026] judging whether the battery pack is in a static state;

[0027] If the battery pack is in a static state, the duty cycle of the magnetic saturation type self-excitation drive virtual parallel battery equalization circuit of the battery pack remains unchanged;

[0028] If the battery pack is not in a static state, judging the charge and discharge state of the battery pack;

[0029] If the battery pack is in a discharge state, increasing the duty cycle according to a set ratio;

[0030] If the battery pack is in a charge state, reducing the duty cycle according to a set ratio.

[0031] Optionally, the range of the set ratio is 10% to 20%.

[0032] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0033] In the present invention, the switching tube in the first balancing unit starting from the negative electrode of the slave battery pack is driven by an externally input external driving signal, and the switching tubes in other balancing units are driven by positive feedback through corresponding self-exciting windings, realizing self-exciting drive for the on and off of the switching tubes, simplifying the driving circuit, reducing the circuit volume, and lowering the cost of the balancing circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 FIG. 1 is a schematic structural diagram of a magnetic saturation self-exciting drive virtual parallel battery balancing circuit provided by an embodiment of the present invention;

[0036] Figure 2 FIG. 2 is a schematic structural diagram of a series battery pack equivalent to a virtual parallel circuit provided by an embodiment of the present invention;

[0037] Figure 3 FIG. 3 is a schematic flowchart of a magnetic saturation self-exciting drive virtual parallel battery balancing method provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] The purpose of the present invention is to provide a magnetic saturation self-exciting drive virtual parallel battery balancing circuit, system and method, which simplifies the driving circuit and reduces the cost of the balancing circuit.

[0040] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0041] Embodiment 1

[0042] This embodiment provides a magnetic saturation self-exciting drive virtual parallel battery balancing circuit, as Figure 1As shown in the figure, a magnetic saturation self-excited drive virtual parallel battery equalization circuit of the present invention includes: a battery pack composed of n series-connected single battery units, n equalization units, n self-excited windings, 1 magnetic reset winding, and an external drive signal; each of the single battery units includes a single battery and a single battery internal resistance connected in series, each of the single battery units is connected in parallel with one of the equalization units, and each of the equalization units includes an equalization winding and a switching tube connected in series; the equalization windings are arranged in one-to-one correspondence with the self-excited windings, the same-named ends of each of the equalization windings and each of the self-excited windings are the same, the same-named end of the magnetic reset winding is opposite to that of the equalization winding, and the magnetic reset winding is connected to the positive electrode of the battery pack through a diode; the external drive signal is used to drive the switching tube in the first equalization unit starting from the negative electrode of the battery pack; the gate of the switching tube in the m-th equalization unit is connected to the positive electrode of the self-excited winding corresponding to the m-th equalization unit, and the source of the switching tube in the m-th equalization unit is connected to the negative electrode of the self-excited winding corresponding to the m-th equalization unit, where n is an integer greater than 3.

[0043] The external drive signal is further used to control the duty cycle of the magnetic saturation self-excited drive virtual parallel battery equalization circuit by controlling the cut-off time of the switching tube in the first equalization unit.

[0044] The drive signal of the switching tube S in the first equalization unit 1 includes an external drive signal and positive feedback drive generated by the self-excited winding corresponding to the switching tube S 1 , and the drive signals of the switching tubes S 1 ~switching tubes S n in the 2nd to the nth equalization units are only driven by positive feedback through the corresponding self-excited windings, that is, the switching tube S 1 has two drives, one external drive and one self-excited drive. The switching tubes S 2 ~switching tubes S n only have one self-excited drive. The external drive signal triggers the switching tube S 1 to conduct, and through positive feedback, the switching tubes S 1 ~switching tubes S n are conducted. After magnetic saturation, the switching tubes S 1 ~switching tubes S n are cut off.

[0045] Figure 1 In, V B1 , V B2 and V Bn are the first single battery, the second single battery, and the nth single battery respectively, and the first single battery, the second single battery, and the nth single battery are located in the first single battery unit, the second single battery unit, and the nth single battery unit respectively. R 1 , R 2 , Rn are the internal resistances of the first single cell, the second single cell, and the nth single cell, respectively. Switch S 1 , switch S 2 , and switch S n are the switches in the first balancing unit, the second balancing unit, and the nth balancing unit, respectively. The inductance of each balancing winding is L, and the number of turns is n 1 .

[0046] G 1 , G 2 , G n are the drive signals of switch S 1 , switch S 2 , and switch S n , respectively. Among them, the drive signal G 1 includes the external drive signal controlled by the external circuit for switch S 1 and also includes the positive feedback drive through the corresponding self-excited winding. The drive signals G 2 to G n include the positive feedback drive through the corresponding self-excited winding. The number of turns of the self-excited winding is n 3 .

[0047] The drive signal of the switch in the present invention is provided through the self-excited winding, and there is no need to design an independent drive circuit additionally. The circuit is simple, small in size, and low in cost.

[0048] Self-excited drive principle: The drive of switch S 1 is provided with a conduction trigger signal by the external circuit to drive conduction. The magnetic flux of the magnetic core increases, and voltage is induced in each self-excited winding to drive the respective switches S 1 , S 2 , S n to conduct. The circuit enters the virtual parallel automatic balancing state. The exciting current of each balancing winding also continues to increase until the magnetic core saturates, the magnetic flux linkage no longer increases, and the induced voltage in each self-excited winding decreases to zero, thereby driving the switches S 2 ...S n to cut off. The circuit exits the virtual parallel automatic balancing state.

[0049] 1) The calculation process of the balancing current is as follows:

[0050]

[0051] Since the exciting current is relatively small compared to the balancing current, the exciting current can be ignored when calculating the balancing current.

[0052] Among them, E 1 , E 2 , E n respectively represent the single cells V B1 , VB2 , the voltage of V Bn , where U is the virtual parallel voltage. g 1 , g 2 , g m respectively represent the conductance of the first equalizing circuit, the second equalizing circuit, and the m-th equalizing circuit. The conductance of the equalizing circuit is the reciprocal of the resistance of the equalizing circuit. The value range of m is from 1 to n. The resistance of each equalizing circuit is composed of the internal resistance of the battery, the internal resistance of the equalizing winding, and the internal resistance of the connecting wire in series.

[0053] I 1 represents the equalizing current of the first equalizing winding, I 2 represents the equalizing current of the second equalizing winding, I m represents the equalizing current of the m-th equalizing winding.

[0054] The exciting current of each equalizing winding is expressed as follows.

[0055]

[0056] Among them, i em is the exciting current of the m-th equalizing winding, i e is the total exciting current, and t is time.

[0057] Since the virtual parallel voltage U is basically constant and the change amplitude is small, the exciting current can increase approximately linearly.

[0058] The exciting current starts from zero in each cycle.

[0059]

[0060] It can be obtained that:

[0061]

[0062] The virtual parallel voltage U is expressed as:

[0063]

[0064] Each equalizing current is expressed as:

[0065]

[0066]

[0067]

[0068] 2) The magnetically saturated exciting current i es and the conduction time t on The calculation process is as follows.

[0069] The total exciting current is expressed as:

[0070]

[0071] The exciting current of each balancing winding is expressed as:

[0072]

[0073] The magnetic flux linkage of each balancing winding is expressed as:

[0074] Ψ 1 = L ie 1 ;

[0075] Ψ 2 = L ie 2 ;

[0076] Ψ n = L i en ;

[0077]

[0078] Among them, Ψ 1 , Ψ 2 , Ψ n are the magnetic flux linkages of the 1st balancing winding, the 2nd balancing winding and the nth balancing winding respectively, Ψ is the total magnetic flux linkage of each balancing winding, the magnetic flux linkage at magnetic saturation is Ψ s , and the exciting current is i es .

[0079] Ψ s = L i es ;

[0080]

[0081] Among them, t on is the conduction time.

[0082] Then,

[0083]

[0084] Among them, D represents the duty cycle, t on represents the conduction time of the switching device in the 1st balancing unit, t off is the cut-off time of the switching device in the 1st balancing unit, Ψ s represents the magnetic flux linkage at magnetic saturation, g m represents the conductance of the mth balancing loop formed by the mth single battery unit and the mth balancing unit. The resistance of the mth balancing loop is composed of the internal resistance of the single battery, the internal resistance of the balancing winding and the internal resistance of the connecting wire in series, and E m represents the voltage of the mth single battery.

[0085] The magnetic flux linkage Ψ at magnetic saturation s is expressed as: Ψ s = n 1 B S S;

[0086] where n 1 represents the number of turns of each of the said balancing windings, B S represents the magnetic induction intensity at magnetic core saturation, and S represents the cross-sectional area of the magnetic core.

[0087] Figure 1 In Figure 1 , i 1 , i 2 , i n are all the superposition of the exciting current and the balancing current.

[0088] 3) The magnetic reset time t f The calculation process is as follows.

[0089] After n switching tubes are turned off, the magnetic reset winding (also called the demagnetizing winding) starts the magnetic reset operation. The exciting energy of the balancing winding is fed to the battery pack through the magnetic reset winding, and the current in the magnetic reset winding gradually decreases to zero, and the magnetic reset is completed. This period is the magnetic reset time t f .

[0090] When n switching tubes are turned off, the exciting current of n balancing windings is all i e / n, and the magnetic reset current

[0091]

[0092] The magnetic reset time t f and the number of turns n 2 of the magnetic reset winding satisfy:

[0093]

[0094] Also, E represents the rated operating voltage of a single battery, and E is approximately equal to U / n (the virtual parallel voltage divided by n).

[0095] So t f and n 2 satisfy:

[0096] 4) The cut-off time t off The control requirements are as follows.

[0097] The conduction time of the magnetic saturation self-excited drive virtual parallel balancing circuit is determined by the magnetic core saturation magnetic flux linkage and the virtual parallel voltage, and is not controlled by the external control signal G 1 . The external control signal G 1 only triggers S 1Conduction. The external control signal G 1 can only control the duty cycle D by controlling the cut-off time t off .

[0098] The duty cycle D of the equalization circuit is expressed as:

[0099]

[0100] The cut-off time t off must be greater than or equal to the magnetic reset time t f . Therefore, the maximum duty cycle of the external control signal is: Generally, the number of turns n of the magnetic reset winding 2 is taken and the maximum duty cycle is about 80%.

[0101] During the cut-off time t off , the battery stops equalizing, which is beneficial to depolarization and beneficial to extending the battery life.

[0102] Figure 2 The series battery pack is equivalent to a circuit of virtual parallel connection. V B1 ~V Bn are individual cells, and R 1 ~R n are the internal resistances of individual cells, and i b1 , i b2 , i bn are all the superposition of the charge-discharge current and the equalization current. Figure 2 In it, U T is the virtual parallel voltage after equivalence.

[0103] The self-excited windings are sequentially connected in series with a first resistor and a second resistor. The positive pole of the second resistor is connected to the gate of the corresponding switching tube, and the negative pole of the second resistor is connected to the source of the corresponding switching tube.

[0104] Due to various reasons, the aging degrees of the performances of individual cells are not the same, which is manifested as the obvious increase in the internal resistance of the individual cell with poor performance.

[0105] When the battery pack is in the charging state, the charging currents of individual cells are the same, but the terminal voltage of the individual cell with poor performance is significantly higher. At this time, the equalization circuit works, and the equalization current of the individual cell with higher terminal voltage is larger and is significantly offset by the charging current, seriously affecting the charging effect.

[0106] Therefore, when the battery pack is in the charging state, the duty cycle of controlling the equalization current should be appropriately reduced, that is, it should be appropriately reduced compared with the duty cycle of the equalization current when the battery pack is in the static state.

[0107] When the battery pack is in the discharge state, the discharge current of each single battery is the same. The terminal voltage of the single battery with poor performance is significantly lower, and the energy supply is significantly insufficient. At this time, the equalization circuit works, and the duty cycle of the equalization current needs to be appropriately increased, that is, the duty cycle of the equalization current is appropriately increased compared with that when the battery pack is in the static state, so as to make up for the insufficient energy supply of the single battery with poor performance. The control strategy of the duty cycle of the equalization current during the charge and discharge of the battery pack is as Figure 3 shown.

[0108] The present invention uses the magnetic saturation of the self-excited winding and the equalization winding to realize the self-excited drive circuit and method for the on and off of the switching tube, without a complex isolation drive circuit. The drive circuit is simple in circuit, small in size and low in cost.

[0109] The present invention realizes the quantitative analysis of parameters such as the equalization current of the virtual parallel equalization circuit, the magnetic saturation excitation current i es and the conduction time ton, the magnetic reset time t f etc., and gives specific calculation methods and requirements.

[0110] The present invention provides an equalization control strategy based on the change of the duty cycle of the equalization current with the charge and discharge state of the series battery pack, which can reasonably adjust the duty cycle under different working states to realize the optimization of voltage equalization in the static state and the charge and discharge state.

[0111] A magnetic saturation type self-excited drive virtual parallel battery equalization circuit of the present invention is applicable to the voltage equalization of various lithium batteries, lead-acid batteries and supercapacitors.

[0112] The self-excited drive circuit of the present invention is applicable to other multi-winding isolation drive circuits.

[0113] Embodiment 2

[0114] This embodiment provides a magnetic saturation type self-excited drive virtual parallel battery equalization system, which includes the magnetic saturation type self-excited drive virtual parallel battery equalization circuit described in Embodiment 1.

[0115] Embodiment 3

[0116] This embodiment provides a magnetic saturation type self-excited drive virtual parallel battery equalization method, which applies the magnetic saturation type self-excited drive virtual parallel battery equalization circuit described in Embodiment 1, as Figure 3 shown, and this method includes the following steps.

[0117] Judge whether the battery pack is in the static state.

[0118] If the battery pack is in the static state, the duty cycle of the magnetic saturation type self-excited drive virtual parallel battery equalization circuit of the battery pack remains unchanged.

[0119] If the battery pack is not in a static state, then determine the charge and discharge state of the battery pack.

[0120] If the battery pack is in a discharge state, then increase the duty ratio according to a set ratio.

[0121] If the battery pack is in a charging state, then decrease the duty ratio according to a set ratio.

[0122] The range of the set ratio is from 10% to 20%.

[0123] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, reference can be made to each other.

[0124] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A magnetic saturation self-excited drive virtual parallel battery equalization circuit, characterized in that, it includes: a battery pack composed of n series-connected single battery cells, n equalization units, n self-excited windings, 1 magnetic reset winding, and an external drive signal; each of the single battery cells includes a single battery and a single battery internal resistance connected in series, and each of the single battery cells is connected in parallel with one of the equalization units, and each of the equalization units includes an equalization winding and a switching tube connected in series; the equalization windings are arranged in one-to-one correspondence with the self-excited windings, the same-named ends of each of the equalization windings and each of the self-excited windings are the same, the same-named end of the magnetic reset winding is opposite to that of the equalization winding, and the magnetic reset winding is connected to the positive pole of the battery pack through a diode; the external drive signal is used to drive the switching tube in the first equalization unit starting from the negative pole of the battery pack; the gate of the switching tube in the mth equalization unit is connected to the positive pole of the self-excited winding corresponding to the mth equalization unit, and the source of the switching tube in the mth equalization unit is connected to the negative pole of the self-excited winding corresponding to the mth equalization unit; the external drive signal is also used to control the duty cycle of the magnetic saturation self-excited drive virtual parallel battery equalization circuit by controlling the cut-off time of the switching tube in the first equalization unit, and the duty cycle is expressed as: Among them, D represents the duty cycle, t on represents the conduction time of the switching transistor in the first equalization unit, t off the cut-off time of the switching transistor in the first equalization unit, Ψ s represents the magnetic flux when magnetic saturation occurs, g m represents the conductance of the m-th equalization loop formed by the m-th single battery unit and the m-th equalization unit. The resistance of the m-th equalization loop is composed of the internal resistance of the single battery, the internal resistance of the equalization winding, and the internal resistance of the connecting wire in series, E m represents the voltage of the m-th single battery; each self-excited winding is sequentially connected in series with a first resistor and a second resistor, the positive pole of the second resistor is connected to the gate of the corresponding switching tube, and the negative pole of the second resistor is connected to the source of the corresponding switching tube.

2. The magnetic saturation self-excited drive virtual parallel battery equalization circuit according to claim 1, characterized in that, The magnetic flux linkage Ψ at magnetic saturation s is expressed as: Ψ s = n 1 B S S; where n 1 represents the number of turns of each of the balance windings, B S represents the magnetic induction intensity when the magnetic core is saturated, and S represents the cross-sectional area of the magnetic core.

3. The magnetic saturation self-excited drive virtual parallel battery equalization circuit according to claim 1, characterized in that, The number of turns of the magnetic reset winding is Among them, n 1 represents the number of turns of each of the balance windings.

4. A magnetic saturation self-excited drive virtual parallel battery equalization system, characterized in that, it includes the magnetic saturation self-excited drive virtual parallel battery equalization circuit according to any one of claims 1-3.

5. A magnetic saturation self-excited drive virtual parallel battery equalization method, applying the magnetic saturation self-excited drive virtual parallel battery equalization circuit according to any one of claims 1-3, characterized in that, this method includes: judging whether the battery pack is in a static state; if the battery pack is in a static state, the duty cycle of the magnetic saturation self-excited drive virtual parallel battery equalization circuit of the battery pack remains unchanged; if the battery pack is not in a static state, judging the charge and discharge state of the battery pack; if the battery pack is in a discharge state, increasing the duty cycle according to a set ratio; if the battery pack is in a charging state, reducing the duty cycle according to a set ratio.

6. The magnetic saturation self-excited drive virtual parallel battery equalization method according to claim 5, characterized in that, the range of the set ratio is 10% to 20%.

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