A control and design method for an adaptive current control circuit of a parallel battery cluster

Abstract

This invention discloses a control and design method for an adaptive current control circuit of parallel battery clusters. When current or state of charge imbalance occurs between different parallel battery clusters, the current flow direction of the parallel battery cluster balancing circuit is controlled according to the upper-level control command. The power of the controlled parallel loop is transferred to other parallel loops through the parallel battery cluster balancing circuit, thereby achieving circulating current suppression and state of charge balancing control among the battery clusters. After balancing control, the parameters of the output inductor and series capacitor of the bidirectional converter of the parallel battery cluster are obtained based on the inductor current ripple rate and capacitor voltage ripple rate. At the same time, the switching transistors are selected based on the voltage and current stress of the bidirectional converter switching transistors. The method of this invention reduces the output inductor current and series capacitor voltage ripple rate, thereby better achieving circulating current suppression and state of charge balancing of the parallel battery clusters.

Description

Technical Field

[0001] This invention belongs to the field of automotive power battery technology, specifically relating to a control and design method for an adaptive current control circuit for parallel battery clusters. Background Technology

[0002] Currently, electric vehicle and hybrid vehicle technologies are developing rapidly. Their power source uses multiple battery clusters connected in parallel to supply power to the vehicle. Therefore, battery status monitoring is particularly important in this system. During charging and discharging, changes in the physical characteristics of the batteries can reduce the consistency of the individual battery clusters, leading to poor performance or even damage, and significantly reducing the lifespan of the battery clusters.

[0003] Meanwhile, the differences in voltage and physical characteristics of batteries during the production process will bring many problems to the control of the subsequent battery system. Furthermore, the energy difference of the battery system gradually increases due to the battery system operating in unequal current modes for a long time, resulting in a rapid decline in the energy utilization rate of the battery system. Therefore, it is very necessary to develop and design a battery balancing system.

[0004] The internal battery balancing process is slow and affected by the battery's external output characteristics. Manual balancing using equipment is labor-intensive, costly, and inefficient, with a long overall balancing time. Active balancing requires sophisticated chip design and has expensive management systems, making them unsuitable for high-efficiency battery balancing. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings and deficiencies of the prior art and propose a control and design method for an adaptive current control circuit of a parallel battery cluster, thereby reducing the output inductor current and the voltage ripple rate of the series capacitor, and thus better achieving circulating current suppression and state of charge balance of the parallel battery cluster.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A control and design method for an adaptive current control circuit for parallel battery clusters is disclosed. The parallel battery cluster balancing circuit topology consists of battery clusters, series capacitors, bidirectional converters, and bidirectional DC / DC converters. The control method is as follows: when current or state of charge imbalance occurs between different parallel battery clusters, the current flow direction of the parallel battery cluster balancing circuit is controlled according to the upper-level control command. The power of the controlled parallel loop is transferred to other parallel loops through the parallel battery cluster balancing circuit, thereby realizing the suppression of circulating current and the balancing control of the state of charge among the battery clusters.

[0008] After equalization control, the parameters of the output inductor and series capacitor of the bidirectional converter with parallel battery clusters are obtained based on the inductor current ripple rate and capacitor voltage ripple rate; at the same time, the switching transistors are selected based on the voltage and current stress of the bidirectional converter switching transistors.

[0009] Furthermore, the bidirectional converter is a composite chopper circuit with a load short-circuit switch.

[0010] Furthermore, the circulation suppression and state-of-charge equalization control are specifically as follows:

[0011] The parallel battery cluster balancing circuit learns the reference current of each battery cluster from the instructions of the superior unit. Then, based on the relationship between the current reference value and the actual output current value of the battery cluster, it controls the polarity of the output voltage of the corresponding series capacitor, thereby controlling the direction of power flow between parallel circuits. It transfers part of the power of the parallel circuit to other parallel circuits through the bidirectional converter and the intermediate bus, thereby achieving circulating current suppression or state of charge balancing of each battery cluster.

[0012] Furthermore, series capacitors C1, C2, ..., C N When the required output voltage is positive, the current reference value of the battery cluster is compared with the sampled current value. The difference is then compared with a triangular carrier wave after passing through a PI regulator, and finally the first switch S of the composite chopper circuit is obtained. i1 Second switch S i2 Third switch S i3 Fourth switch S i4 Drive signal, where the third switch S i3 During this process, the fourth switch S remains off. i4 During this process, the first switch S remains on. i1 Second switch S i2 Based on the modulation result, complementary conduction occurs, with the duty cycle being the first duty cycle D1, thereby controlling the series voltage source U. C1 U C2 ... U CN The average voltage over one cycle is positive.

[0013] Furthermore, when the output voltage of the series capacitor is positive, the parameter design of the bidirectional converter includes the following steps:

[0014] Calculate the series capacitors C1, C2, ..., C based on the battery output current reference value. n Average voltage U C1 =I ref1 ·R eq -U Boc +U o ;

[0015] The output power of the corresponding bidirectional converter can be determined based on the series capacitor voltage value and the corresponding battery cluster output current reference value.

[0016] The duty cycle of the bidirectional converter can be determined based on the voltage values ​​of the intermediate bus capacitor and the series capacitor.

[0017] Based on the ampere-second balance principle of inductor current, the peak-to-peak value of inductor current fluctuation and the minimum inductance value are obtained as follows:

[0018]

[0019] Calculate the peak-to-peak value of the capacitor voltage fluctuation based on the capacitor current, and then determine the minimum capacitance value of the series capacitor:

[0020]

[0021] The switching transistor is selected based on the inductor current and the intermediate bus voltage.

[0022] Furthermore, series capacitors C1, C2, ..., C N When the required output voltage is negative, the current reference value of the battery cluster is compared with the sampled current value. The difference is then compared with a triangular carrier wave after passing through a PI regulator, and finally the first switch S of the composite chopper circuit is obtained. i1 Second switch S i2 Third switch S i3 Fourth switch S i4 Drive signal, wherein the first switch S i1 During this process, the second switch S remains off. i2 During this process, the third switch S remains on. i3 Fourth switch S i4 Based on the complementary conduction of the modulation result, the duty cycle is the second duty cycle D2, thereby controlling the series capacitors C1, C2, ..., C N The average voltage over one cycle is negative.

[0023] Furthermore, when the output voltage of the series capacitor is negative, the parameter design of the bidirectional converter includes the following steps:

[0024] Calculate the series capacitors C1, C2, ..., C based on the battery output current reference value. n Average voltage U C2 =I ref2 ·R eq -U Boc +U o ;

[0025] The output power of the corresponding bidirectional converter can be determined based on the series capacitor voltage value and the corresponding battery cluster output current reference value.

[0026] The duty cycle of the bidirectional converter can be determined based on the voltage values ​​of the intermediate bus capacitor and the series capacitor.

[0027] Based on the ampere-second balance principle of inductor current, the peak-to-peak value of inductor current fluctuation and the minimum inductance value are obtained as follows:

[0028]

[0029] Calculate the peak-to-peak value of the capacitor voltage fluctuation based on the capacitor current, and then determine the minimum capacitance value of the series capacitor:

[0030]

[0031] Finally, the switching transistor is selected based on the inductor current and the intermediate bus voltage.

[0032] Furthermore, when series capacitors C1, C2, ..., C... n When the output voltage is zero, the current or state of charge of the corresponding battery cluster does not need to be balanced, and the corresponding load short-circuit switch is turned on.

[0033] Furthermore, the reference value of the intermediate bus capacitor voltage is compared with the sampled actual intermediate capacitor voltage value. The result is processed by a PI regulator to obtain the reference current value required for balancing the intermediate bus capacitor voltage. This reference current value is then provided to the bidirectional DC / DC converter to stabilize the intermediate bus capacitor voltage. Finally, this reference current value is compared with the actual current value of the bidirectional DC / DC converter, and the PI regulator is used to obtain the drive signal for the bidirectional DC / DC converter. This ensures that the fluctuation amplitude of the intermediate bus capacitor voltage is zero during system operation, satisfying the equation...

[0034] Furthermore, comparing the minimum inductance and capacitance design values ​​for the first, second, ..., nth bidirectional converters when the series capacitors are of positive and negative polarity, the larger value is selected as the minimum standard for inductance and capacitance design:

[0035] L 0min =max(L +min ,L -min ),C 0min =max(C +min C -min ).

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] 1. The method of the present invention limits the output inductor current ripple, series capacitor voltage ripple rate, and voltage and current stress of the bidirectional converter switching transistor. It designs and selects the output inductor, series capacitor, and switching transistor of the bidirectional converter, which helps to reduce the corresponding output inductor current ripple and series capacitor voltage ripple and reduce losses. Attached Figure Description

[0038] Figure 1 This is a block diagram of the parallel battery cluster circulating current suppression control method of the present invention;

[0039] Figure 2 This is a block diagram of the parallel battery cluster state-of-charge equalization control method of the present invention;

[0040] Figure 3 This is a topology diagram of a parallel battery cluster that integrates circulating current suppression and state-of-charge balancing circuits according to the present invention.

[0041] Figure 4 This is a topology diagram of an embodiment of the present invention;

[0042] Figure 5 This is a diagram showing the positive polarity series capacitor voltage output drive signal and related waveforms according to an embodiment of the present invention.

[0043] Figure 6 This is a diagram showing the negative polarity series capacitor voltage output drive signal and related waveforms in an embodiment of the present invention. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0045] Example

[0046] like Figure 1 As shown, the present invention provides a control and design method for an adaptive current control circuit of a parallel battery cluster, comprising:

[0047] The parallel battery cluster balancing circuit topology consists of battery clusters, series capacitors, bidirectional converters, and bidirectional DC / DC converters. The control method is as follows: when there is an imbalance in current or state of charge between different parallel battery clusters, the balancing circuit will obtain the reference current value of each battery cluster according to the instructions from the upper level. Then, based on the relationship between the current reference value and the actual output current value of the battery cluster, it will control the polarity of the output voltage of the corresponding series capacitor, thereby controlling the direction of power flow between parallel circuits. The power of some parallel circuits will be transferred to other parallel circuits through the bidirectional converter and the intermediate bus, thereby achieving circulating current suppression or state of charge balancing of each battery cluster.

[0048] After equalization control, the parameters of the output inductor and series capacitor of the bidirectional converter with parallel battery clusters are obtained based on the inductor current ripple rate and capacitor voltage ripple rate; at the same time, the switching transistors are selected based on the voltage and current stress of the bidirectional converter switching transistors.

[0049] In this embodiment, as Figure 1 As shown, when there is an imbalance in the state of charge or current among the battery clusters, by controlling the switching of the switching transistors in each bidirectional converter and the bidirectional DC / DC converter, the power of some parallel circuits can be transferred to other parallel circuits through the common output bus of the parallel battery clusters. This achieves the suppression of circulating current and the balance of the state of charge among the battery clusters. For circuits that do not require current or state of charge balancing, it is only necessary to turn on the load short-circuit switch of the bidirectional converter of the module and turn on and off the relevant switching transistors to achieve the blocking of the battery cluster.

[0050] like Figure 1 As shown, the reference value of the intermediate bus capacitor voltage is compared with the sampled actual voltage value. The result is passed through a PI regulator to obtain the reference value of the current required to balance the intermediate bus capacitor voltage. Then, it is given to the bidirectional DC / DC converter to stabilize the current value required to stabilize the intermediate bus capacitor voltage. The result is then compared with the actual current value to obtain the drive signal of the bidirectional DC / DC converter, thereby maintaining the intermediate bus capacitor voltage fluctuation amplitude at zero during system operation.

[0051] like Figure 1 As shown, when capacitors C1, C2, ..., C are connected in series... N When the required output voltage is positive, simply compare the current reference value of the battery cluster with the sum of the sampled current value and the additional current reference value required for each parallel battery cluster to maintain the voltage balance of the intermediate bus. The difference is then compared with the triangular carrier wave after passing through the PI regulator to obtain the first switch S of the composite chopper circuit. i1 Second switch S i2 Third switch S i3 Fourth switch S i4 Drive signal, where the third switch S i3 During this process, the fourth switch S remains off. i4 During this process, the first switch S remains on. i1 Second switch S i2 The first switch S is turned on complementaryly according to the modulation result. i1 The duty cycle is D1, thereby controlling the series capacitors C1, C2, ..., C N The average voltage over one cycle is positive.

[0052] like Figure 1As shown, the bidirectional converter is a composite chopper circuit with a load short-circuit switch. When the series capacitors C1, C2, ..., C... N When the required output voltage is negative, simply compare the current reference value of the battery cluster with the sum of the sampled current value and the additional current reference value required for each parallel battery cluster to maintain the voltage balance of the intermediate bus. The difference is then compared with the triangular carrier wave after passing through the PI regulator, and finally obtains the first switch S of the composite chopper circuit. i1 Second switch S i2 Third switch S i3 Fourth switch S i4 Drive signal, wherein the first switch S i1 During this process, the second switch S remains off. i2 During this process, the third switch S remains on. i3 Fourth switch S i4 Based on the complementary conduction of the modulation result, the duty cycle is D2, thereby controlling the series capacitors C1, C2, ..., C N The average voltage over one cycle is negative.

[0053] When capacitors C1, C2, ..., C are connected in series... N When the required output voltage is zero, i.e., when the battery cluster does not require current or state-of-charge equalization control, only the fifth switch M of the composite chopper circuit needs to be controlled. i Enabling this will enable the blocking of the connected bidirectional converters, allowing the series capacitors C1, C2, ..., C to... N The output voltage is zero, thus preventing power balancing in the parallel circuit.

[0054] like Figure 1 and Figure 2 As shown, the reference value of the intermediate bus capacitor voltage is compared with the sampled actual voltage value. The result is passed through a PI regulator to obtain the reference current value required for balancing the intermediate bus capacitor voltage. This reference current value is then given to the bidirectional DC / DC converter to stabilize the intermediate bus capacitor voltage. The reference current value is then compared with the actual current value to obtain the drive signal for the bidirectional DC / DC converter. This ensures that the fluctuation amplitude of the intermediate bus capacitor voltage is zero during system operation, satisfying the equation...

[0055] like Figure 3 The diagram shown is a topology diagram of an adaptive current control circuit for a parallel battery cluster according to the present invention. The parallel battery cluster balancing circuit topology consists of a battery cluster, a series capacitor, a bidirectional converter, and a bidirectional DC / DC converter, wherein the bidirectional converter is a composite chopper circuit with a load short-circuit switch.

[0056] like Figure 4The diagram shown is a specific circuit topology diagram of one embodiment of the present invention.

[0057] like Figure 3 , Figure 4 , Figure 5 as well as Figure 6 As shown, the design steps of this parallel battery cluster balancing circuit embodiment are as follows:

[0058] Let the output voltage of the parallel battery pack before adjustment be U. o The adjusted output voltage is U o * The rated open-circuit voltage of the i-th battery cluster is U. Boc_i The equivalent internal resistance is R. eq_i The output voltage of the i-th battery cluster in the working state is U. B_i The output current is I i The voltage across the i-th series capacitor is U. Ci The voltage of the intermediate bus capacitor is U. C0 Assume that the discharge currents of the first and second battery clusters before current equalization are I1 and I2, respectively. If I1 < I2, then the discharge currents of the first and second battery clusters after current equalization are I1 and I2, respectively. ref1 =I1+ΔI,I ref2 =I2-ΔI, and the duty cycles of the bidirectional converter are D1 and D2, respectively.

[0059] If the parameters of the n battery clusters are all identical, then the rated open-circuit voltage of the battery cluster can be set as U. Boc The equivalent internal resistance is R. eq ;

[0060] For a voltage source where the voltage is positive:

[0061] Step 1: Calculate the first series capacitor C1, the second series capacitor C2, ..., the nth series capacitor C based on the battery output current reference value. n Average voltage.

[0062] During the current equalization process of the first battery cluster:

[0063]

[0064] Solving

[0065] U C1 =I ref1 ·R eq -U Boc +U o >0 (2)

[0066] Step 2: Calculate the output power of the corresponding bidirectional converter based on the series capacitor voltage value and the corresponding battery cluster output current reference value.

[0067] The actual power of the bidirectional converter is:

[0068] P1 = U C1 ·I ref1 =I ref1 2 ·R eq -U Boc ·I ref1 +U o ·I ref1 >0 (3)

[0069] Since the voltage across the series capacitor is kept stable after stabilization, the average current across the series capacitor is 0. Therefore, the average inductor current across the output inductor of the bidirectional converter is I. ref1 ;

[0070] Step 3: Determine the duty cycle of the bidirectional converter based on the voltage values ​​of the intermediate bus capacitor and the series capacitor.

[0071] Assuming the voltage across the series capacitor remains constant during the subsequent cycle after stabilization, the duty cycle of the bidirectional converter is:

[0072]

[0073] Step 4: Based on the ampere-second balance principle of inductor current, determine the peak-to-peak value of the inductor current fluctuation and the minimum inductance value;

[0074] In steady state, the peak-to-peak value of the inductor current fluctuation is:

[0075]

[0076] Substituting into equation (2), we get:

[0077]

[0078] If we calculate based on a 40% inductor current ripple rate:

[0079]

[0080] The minimum inductance when the voltage across the series capacitor is positive is obtained:

[0081]

[0082] Step 5: Calculate the peak-to-peak value of the capacitor voltage fluctuation based on the capacitor current, and obtain the minimum capacitance value of the series capacitor:

[0083] i C =iL -I ref1 (9)

[0084] The peak-to-peak value of its capacitor voltage fluctuation is the integral area in the figure:

[0085]

[0086] If calculated based on a 15% capacitor voltage ripple rate:

[0087]

[0088] The minimum series capacitance can be obtained when the voltage source voltage is positive:

[0089]

[0090] Step 6: Select the switching transistor based on the inductor current and the intermediate bus voltage;

[0091] The maximum current flowing through the switching transistor is:

[0092] I s =1.2I ref1 (13)

[0093] The voltage that the switching transistor withstands is:

[0094] U s =U C0 (14)

[0095] Therefore, the selected switching transistor should meet the following conditions regarding rated voltage and rated current:

[0096] U N ≈2U s =2U C0 (15)

[0097] I N =2I s =2.4I ref1 (16)

[0098] For a voltage source with a negative polarity:

[0099] Step 1: Calculate the first series capacitor C1, the second series capacitor C2, ..., the nth series capacitor C based on the battery output current reference value. n Average voltage.

[0100] During the current equalization process of the first battery cluster:

[0101]

[0102] Solving

[0103] UC2 =I ref2 ·R eq -U Boc +U o <0 (18)

[0104] Step 2: Calculate the output power of the corresponding bidirectional converter based on the series capacitor voltage value and the corresponding battery cluster output current reference value.

[0105] The actual power of the bidirectional converter is:

[0106] P2 = U C2 ·I ref2 =I ref2 2 ·R eq -U Boc ·I ref2 +U o ·I ref2 <0 (19)

[0107] Since the voltage across the series capacitor is kept stable after stabilization, the average current across the series capacitor is 0. Therefore, the average inductor current across the output inductor of the bidirectional converter is I. ref2 ;

[0108] Step 3: Determine the duty cycle of the bidirectional converter based on the voltage values ​​of the intermediate bus capacitor and the series capacitor.

[0109] Assuming the voltage across the series capacitor remains constant during one cycle, the duty cycle of the bidirectional converter is:

[0110]

[0111] Step 4: Based on the ampere-second balance principle of inductor current, determine the peak-to-peak value of the inductor current fluctuation and the minimum inductance value;

[0112] In steady state, the peak-to-peak value of the inductor current fluctuation is:

[0113]

[0114] Substituting into formula (2), we get:

[0115]

[0116] If we calculate based on a 40% inductor current ripple rate:

[0117]

[0118] The minimum inductance when the voltage across the series capacitor is positive is obtained:

[0119]

[0120] Step 5: Calculate the peak-to-peak value of the capacitor voltage fluctuation based on the capacitor current, and obtain the minimum capacitance value of the series capacitor:

[0121] i C =i L -I ref2 (25)

[0122] The peak-to-peak value of its capacitor voltage fluctuation is the integral area in the figure:

[0123]

[0124] If calculated based on a 15% capacitor voltage ripple rate:

[0125]

[0126] The minimum series capacitance can be obtained when the voltage across the series capacitor is positive:

[0127]

[0128] Step 6: Select the switching transistor based on the inductor current and the intermediate bus voltage;

[0129] The maximum current flowing through the switching transistor is:

[0130] I s =1.2I ref2 (29)

[0131] The voltage that the switching transistor withstands is:

[0132] U s =U C0 (30)

[0133] The selected switching transistor should meet the following conditions regarding rated voltage and rated current:

[0134] U N ≈2U s =2U C0 (31)

[0135] I N =2I s =2.4I ref2 (32)

[0136] Finally, let

[0137] L0 = max(L + ,L - ),C0=max(C + C - (33)

[0138] The parameters of the actual inductor and series capacitor should satisfy:

[0139] L≥L0, C≥C0 (34)

[0140] It should also be noted that, in this specification, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0141] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of control and design of adaptive current control circuit for parallel battery clusters, characterized by, The parallel battery cluster equalization circuit topology is composed of a battery cluster, a series capacitor, a bidirectional converter and a bidirectional DC / DC converter; the control method is that when the current or state of charge is unbalanced between different parallel battery clusters, the current flow direction of the parallel battery cluster equalization circuit is controlled according to the upper control instruction, and the power of part of the parallel loops is transmitted to other parallel loops through the parallel battery cluster equalization circuit, so as to realize the circulation suppression and the state of charge equalization control between the battery clusters; After the equalization control, the parameters of the output inductor of the bidirectional converter of the parallel battery cluster and the series capacitor are obtained according to the inductor current ripple ratio and the capacitor voltage ripple ratio, including the following steps: The average value of the series capacitor voltage is calculated according to the battery output current reference value; The output power of the corresponding bidirectional converter is obtained according to the series capacitor voltage value and the corresponding battery cluster output current reference value; The working duty cycle of the bidirectional converter is obtained according to the intermediate bus capacitor voltage and the series capacitor voltage value; The inductor current fluctuation peak-to-peak value and the minimum inductance value are obtained according to the inductor current ampere-second balance principle; The capacitor voltage fluctuation peak-to-peak value is calculated according to the capacitor current, and the minimum value of the series capacitor capacitance is obtained; Meanwhile, the switch tube is selected according to the voltage and current stress of the switch tube of the bidirectional converter.

2. The method of claim 1, wherein the method is characterized by: The bidirectional converter is a composite chopper circuit with load short circuit switch.

3. The method of control and design of an adaptive current control circuit for a parallel battery cluster of claim 1, wherein, The circulation suppression and the state of charge equalization control are as follows: The parallel battery cluster equalization circuit obtains the reference current value of each battery cluster according to the upper instruction, and then controls the polarity of the output voltage of the corresponding series capacitor according to the size relationship between the current reference value and the actual output current value of the battery cluster, so as to control the flow direction of the power between the parallel loops, and transmit part of the power of the parallel loops to other parallel loops through the bidirectional converter and the intermediate bus, so as to realize the circulation suppression or the state of charge equalization of each battery cluster.

4. The method of control and design of an adaptive current control circuit for a parallel battery cluster of claim 3, wherein, series capacitors C1, C2,..., C N When the required output voltage is positive, the current reference value of the battery cluster is compared with the sampled current value, the difference is compared with the triangular carrier after PI regulator, and the first switch S i1 , the second switch S i2 , the third switch S i3 , the fourth switch S i4 drive signal, where the third switch S i3 is continuously off, the fourth switch S i4 is continuously on, the first switch S i1 , the second switch S i2 is complementary on according to the modulation result, and the duty cycle is the first duty cycle D1, thereby controlling the series voltage source U C1 , U C2 ,..., U CN The average voltage in a period is positive.

5. The method of control and design of an adaptive current control circuit for a parallel battery cluster of claim 4, wherein, When the series capacitor output voltage is positive, the parameter design of the bidirectional converter includes the following steps: The series capacitor C1, series capacitor C2,..., series capacitor Cn are calculated from the battery output current reference value. n Voltage average value ; The output power of the corresponding bidirectional converter is obtained according to the series capacitor voltage value and the corresponding battery cluster output current reference value; The duty cycle of the bidirectional converter is derived from the intermediate bus capacitor voltage and the series capacitor voltage value ; The inductor current fluctuation peak-to-peak value and the minimum inductance value are obtained according to the inductor current ampere-second balance principle: ； The capacitor voltage fluctuation peak-to-peak value is calculated according to the capacitor current, and the minimum value of the series capacitor capacitance is obtained: ； The switch tube is selected according to the inductor current and the intermediate bus voltage.

6. The method of control and design of an adaptive current control circuit for parallel battery clusters according to claim 2, wherein, series capacitors C1, C2,..., C N When the required output voltage is negative, the current reference value of the battery cluster is compared with the sampled current value, and the difference is compared with a triangular carrier after PI regulator, and finally the first switch S i1 , the second switch S i2 , the third switch S i3 , the fourth switch S i4 drive signal, wherein the first switch S i1 is continuously off during this process, the second switch S i2 is continuously on during this process, the third switch S i3 , the fourth switch S i4 is complementary on according to the modulation result, and the duty cycle is the second duty cycle D2, thereby controlling the series capacitors C1, C2,..., C N The average voltage in a period is negative.

7. The method of control and design of an adaptive current control circuit for a parallel battery cluster of claim 2, wherein, When the series capacitor output voltage is negative, the parameter design of the bidirectional converter includes the following steps: The series capacitor C1, series capacitor C2,..., series capacitor Cn are calculated from the battery output current reference value n Voltage average value ; The output power of the corresponding bidirectional converter is obtained according to the series capacitor voltage value and the corresponding battery cluster output current reference value; The duty cycle of the bidirectional converter is derived from the intermediate bus capacitor voltage and the series capacitor voltage value ; The inductor current fluctuation peak-to-peak value and the minimum inductance value are obtained according to the inductor current ampere-second balance principle: ； The capacitor voltage fluctuation peak-to-peak value is calculated according to the capacitor current, and the minimum value of the series capacitor capacitance is obtained: ； Finally, the switch tube is selected according to the inductor current and the intermediate bus voltage.

8. The method of control and design of an adaptive current control circuit for parallel battery clusters according to claim 1, wherein, When the series capacitor C1, series capacitor C2,..., series capacitor C n When the output voltage is zero, the current or state of charge of the corresponding battery cluster does not need to be balanced, and the corresponding load short-circuit switch is turned on.

9. The method of control and design of an adaptive current control circuit for parallel battery clusters according to claim 1, wherein, The intermediate bus capacitor voltage reference value is compared with the actual intermediate capacitor voltage value obtained by sampling, the result is subjected to PI regulator to obtain the current reference value required for intermediate bus capacitor voltage balance, then given to the bidirectional DC / DC converter to stabilize the current value required for intermediate bus capacitor voltage stabilization, finally compared with the actual current value of the bidirectional DC / DC converter to obtain the driving signal of the bidirectional DC / DC converter through the PI regulator, so as to maintain the intermediate bus capacitor voltage fluctuation amplitude to be zero during the system operation, satisfying the equation .

10. The method of control and design of an adaptive current control circuit for parallel battery clusters according to claim 1, wherein, The minimum values of the inductance and the capacitance of the corresponding series capacitor of the first bidirectional converter, the second bidirectional converter, …, the nth bidirectional converter are compared when the series capacitor is positive and negative, and the larger one is selected as the minimum standard of the inductance and the capacitance design: 。

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