A parallel battery cluster state control system and a circulating current suppression method and a state of charge equalization method thereof

Abstract

The application discloses a parallel battery cluster state control system and a circulating current suppression method and a state of charge equalization method thereof. The state control system comprises a plurality of bus capacitors corresponding to battery clusters one by one, bypass switches, a control circuit and a common bus capacitor. Each battery cluster is connected with the bus capacitor in series as a whole. The input end of the control circuit is connected with the corresponding bus capacitor. The output end of the control circuit is connected with the common bus capacitor. The control circuit can control the positive and negative of the voltage of the corresponding bus capacitor, thereby adjusting the current of the corresponding battery cluster. The state control system comprises the bus capacitor, the control circuit and the common bus capacitor, can realize the circulating current suppression and the state of charge equalization control of the parallel battery cluster, and provides the circulating current suppression method and the state of charge equalization method of the parallel battery cluster state control system.

Description

Technical Field

[0001] This invention relates to the field of battery management systems for automotive power batteries, energy storage power stations, and battery cascade utilization, and in particular to a parallel battery cluster state control system and its circulating current suppression method and state-of-charge balancing method. Background Technology

[0002] Due to inconsistencies in battery manufacturing, operating environment, and aging, the open-circuit voltage and equivalent series resistance of each battery cell vary to varying degrees. This leads to inconsistent states of charge (SOCs) among parallel battery clusters during operation. During charging, one cluster may be fully charged while others are not. To prevent overcharging of the charged cluster, the remaining clusters will not be fully charged. Similarly, during discharging, one cluster may reach its minimum permissible SOC while others can still discharge. To prevent damage from over-discharging the charged cluster, all parallel and series-connected battery cells will stop discharging. Therefore, the usable capacity of parallel battery clusters can only reach the capacity of the weakest cluster, resulting in a severe parallel mismatch problem. This prevents the full utilization of the capacity of other parallel battery clusters, reducing the overall system capacity. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a parallel battery cluster state control system. This system achieves circulating current suppression and state-of-charge balancing of the battery cluster by introducing a bus capacitor, a control circuit, and a common bus capacitor. It employs a series converter architecture, achieving full power balancing of the battery cluster with only a small portion of the control circuit power. The circuit is simple and highly efficient. The invention also provides a circulating current suppression method and a state-of-charge balancing method for this parallel battery cluster state control system.

[0004] According to a first aspect of the present invention, a parallel battery cluster state control system is provided, characterized in that it includes: a plurality of bus capacitors corresponding one-to-one with each battery cluster, a bypass switch and a control circuit, and a common bus capacitor;

[0005] The positive ends of the battery clusters are connected to each other to form the positive ends of the parallel battery clusters;

[0006] The positive terminal of the bus capacitor is connected to the negative terminal of the corresponding battery cluster.

[0007] The negative terminals of the bus capacitors are connected to each other to serve as the negative terminals of the parallel battery cluster.

[0008] The positive terminal of the bypass switch is connected to the positive terminal of the corresponding bus capacitor, and the negative terminal of the bypass switch is connected to the negative terminal of the corresponding bus capacitor.

[0009] The positive input terminal of the control circuit is connected to the positive terminal of the corresponding bus capacitor, and the negative input terminal of the control circuit is connected to the negative terminal of the corresponding bus capacitor.

[0010] The positive output terminals of the control circuit are interconnected and connected to the positive terminal of the common bus capacitor.

[0011] The negative output terminals of the control circuit are interconnected and connected to the negative terminal of the common bus capacitor.

[0012] The control circuit can control the positive and negative voltage of the corresponding bus capacitor, thereby adjusting the current of the corresponding battery cluster.

[0013] Preferably, the plurality of control circuits can be controlled to adjust the voltage of the common bus capacitor;

[0014] When the voltage of the bus capacitor is positive, the corresponding control circuit can controllably adjust the magnitude of the positive voltage of the bus capacitor.

[0015] When the voltage of the bus capacitor is negative, the corresponding control circuit can controllably adjust the magnitude of the negative voltage of the bus capacitor.

[0016] Preferably, each of the control circuits can switch between bypass mode and access mode;

[0017] When the bypass switch is connected, the corresponding control circuit operates in bypass mode;

[0018] When the bypass switch is disconnected, the corresponding control circuit operates in access mode.

[0019] Preferably, each of the control circuits is a bidirectional full-bridge converter circuit, comprising: a full-bridge circuit, a first inductor, and a second inductor;

[0020] One end of the first inductor serves as the positive input terminal of the control circuit;

[0021] The other end of the first inductor is connected to a midpoint of the full-bridge circuit;

[0022] One end of the second inductor is connected to the negative input terminal of the control circuit;

[0023] The other end of the second inductor is connected to the other midpoint of the full-bridge circuit;

[0024] The positive terminal of the DC terminal of the full-bridge circuit serves as the positive output terminal of the control circuit.

[0025] The negative terminal of the DC terminal of the full-bridge circuit serves as the negative output terminal of the control circuit.

[0026] Preferably, each of the control circuits adjusts the voltage magnitude and the positive / negative value of the voltage of the common bus capacitor by controlling the switching transistor of the full-bridge circuit.

[0027] According to a second aspect of the present invention, a circulating current suppression method is provided for the parallel battery cluster state control system, comprising:

[0028] S101: Collect the battery current, corresponding bus capacitor voltage, and common bus voltage of each battery cluster through sampling elements;

[0029] S102: Based on the battery current and corresponding bus capacitor voltage of each battery cluster, determine the operating mode of the corresponding control circuit, and obtain the battery current setpoint and common bus voltage setpoint for each battery cluster.

[0030] S103: Control the battery status of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage.

[0031] Preferably, in step S102, the operating mode of the corresponding control circuit is determined based on the battery current and the corresponding bus capacitor voltage of each battery cluster, and the battery current setpoint and the common bus voltage setpoint for each battery cluster are obtained. Specifically, this includes:

[0032] The average battery current is obtained by averaging the battery currents of all collected battery clusters.

[0033] If the difference between the battery current and the average battery current of the battery cluster is less than a certain difference, the corresponding control circuit is determined to be in bypass mode, and the other control circuits are determined to be in access mode.

[0034] The given value of the battery current for each battery cluster is determined as the average value of the battery current;

[0035] The absolute values ​​of the bus capacitor voltages corresponding to all battery clusters are sorted or compared, and the voltage setpoint of the common bus voltage is determined as the highest absolute value of the bus capacitor voltage.

[0036] Preferably, in step S103, the battery state of each battery cluster is controlled according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage, specifically including:

[0037] If the operating mode of the control circuit is bypass mode, the corresponding bypass switch is connected, and all the switching transistors of the full-bridge circuit of the control circuit are disconnected.

[0038] If the operating mode of the control circuit is the access mode, the bypass switch is opened, and the control circuit adjusts the battery current of the corresponding battery cluster to the battery current setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the voltage setpoint.

[0039] Preferably, in S103, the control circuit adjusts the battery current of the corresponding battery cluster to a given battery current value by controlling the switching transistor of the full-bridge circuit, and the parallel battery cluster status control system adjusts the common bus voltage to a given voltage value, specifically including:

[0040] The common bus capacitor voltage setpoint is compared with the collected common bus capacitor voltage, and the result is passed through a proportional-integral regulator to obtain the common current reference value.

[0041] Divide the common current reference value by the number of control circuits operating in access mode, and add it to the battery current setpoint to obtain the actual battery current setpoint.

[0042] The actual given value of the battery current is compared with the battery current of the collected battery cluster. The result is passed through a proportional-integral regulator to obtain the duty cycle, which controls the switching of the switching transistors of the full-bridge circuit.

[0043] According to a third aspect of the present invention, a state-of-charge balancing method is provided for the parallel battery cluster state control system, comprising:

[0044] S201: Collect the battery current, state of charge, corresponding bus capacitor voltage and common bus voltage of each battery cluster through sampling elements;

[0045] S202: Based on the battery current, state of charge, and corresponding bus capacitor voltage of each battery cluster, determine the operating mode of the corresponding control circuit, and obtain the battery current setpoint and the common bus voltage setpoint for each battery cluster.

[0046] S203: Control the battery status of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage.

[0047] Preferably, in step S202, the operating mode of the corresponding control circuit is determined based on the battery current, state of charge, and corresponding bus capacitor voltage of each battery cluster, and the given values ​​of the battery current and common bus voltage for each battery cluster are obtained. Specifically, this includes:

[0048] The average battery current is obtained by averaging the battery currents of all collected battery clusters.

[0049] The average state of charge (SOC) of all collected battery clusters is obtained by averaging the SOC values.

[0050] The given value of the battery current for each battery cluster is determined as the average value of the battery current;

[0051] The given battery current value for each battery cluster is calculated using the following relationship:

[0052]

[0053]

[0054] I refk =I avg +λ(SOC k -SOC avg )

[0055] Among them, I Batk The SOC represents the battery current, k = 1, ..., n, where k is the kth battery cluster. k λ represents the state of charge, and λ represents the adjustment parameter for the state of charge.

[0056] If the difference between the state of charge of the battery cluster and the given value of the battery current is less than a certain difference, the operating mode of the corresponding control circuit is determined to be bypass mode, and the operating mode of the other control circuits is determined to be access mode.

[0057] The absolute values ​​of the bus capacitor voltages corresponding to all battery clusters are sorted or compared, and the voltage setpoint of the common bus voltage is determined as the highest absolute value of the bus capacitor voltage.

[0058] Preferably, in step S203, the battery state of each battery cluster is controlled according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage, specifically including:

[0059] If the operating mode of the control circuit is bypass mode, the corresponding bypass switch is connected, and all the switching transistors of the full-bridge circuit of the control circuit are disconnected.

[0060] If the operating mode of the control circuit is the access mode, the bypass switch is opened, and the control circuit adjusts the battery current of the corresponding battery cluster to the battery current setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the voltage setpoint.

[0061] Preferably, in S203, the control circuit adjusts the battery current of the corresponding battery cluster to a given battery current value by controlling the switching transistor of the full-bridge circuit, and the parallel battery cluster status control system adjusts the common bus voltage to a given voltage value, specifically including:

[0062] The common bus capacitor voltage setpoint is compared with the collected common bus capacitor voltage, and the result is passed through a proportional-integral regulator to obtain the common current reference value.

[0063] Divide the common current reference value by the number of control circuits operating in access mode, and add it to the battery current setpoint to obtain the actual battery current setpoint.

[0064] The actual given value of the battery current is compared with the battery current of the collected battery cluster. The result is passed through a proportional-integral regulator to obtain the duty cycle, which controls the switching of the switching transistors of the full-bridge circuit.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] (1) The parallel battery cluster state control system provided by the present invention achieves circulating current suppression and state-of-charge balance of the battery cluster by introducing a bus capacitor, a control circuit and a common bus capacitor. It adopts a series converter architecture and can achieve full power balance of the battery cluster with only a very small part of the power control circuit. The circuit is simple and efficient.

[0067] (2) The parallel battery cluster state control system provided by the present invention transmits part of the power of the parallel circuit to other parallel circuits through the bidirectional converter and the common bus by simultaneously controlling the switching of the switching transistors in each bidirectional converter, thereby realizing the suppression of circulating current and the balanced control of the state of charge between each battery cluster.

[0068] (3) The parallel battery cluster status control system provided by the present invention allows the control circuit to switch between bypass mode and access mode via a bypass switch, making the control simple and the switching flexible.

[0069] (4) The circulating current suppression method of the parallel battery cluster state control system provided by the present invention realizes the switching of the operating mode of each battery cluster control circuit, the generation of the battery current setpoint, and the control of the battery current and common capacitor voltage of the battery cluster by comparing and calculating the battery current and the battery setpoint.

[0070] (5) The state-of-charge balancing method of the parallel battery cluster state control system provided by the present invention realizes the switching of the operating mode of each battery cluster control circuit, the generation of the battery current setpoint, and the control of the battery cluster battery current and the common capacitor voltage by comparing and calculating the battery current and the battery setpoint, and comparing and calculating the battery cluster state of charge and the average state of charge.

[0071] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0072] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0073] Figure 1 This is a topology diagram of a parallel battery cluster state control system according to an embodiment of the present invention;

[0074] Figure 2 This is a topology diagram of a parallel battery cluster state control system and control circuit according to an embodiment of the present invention;

[0075] Figure 3 This is a flowchart of a circulating current suppression method for a parallel battery cluster state control system according to an embodiment of the present invention;

[0076] Figure 4 This is a control block diagram of a circulating current suppression method for a parallel battery cluster state control system according to an embodiment of the present invention;

[0077] Figure 5 This is a flowchart of a state-of-charge balancing method for a parallel battery cluster state control system according to an embodiment of the present invention.

[0078] Figure 6 This is a control block diagram of a state-of-charge balancing method for a parallel battery cluster state control system according to an embodiment of the present invention. Detailed Implementation

[0079] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0080] In one embodiment, a parallel battery cluster state control system is provided, the topology of which is shown in the figure below. Figure 1 As shown, it includes: multiple bus capacitors corresponding to each battery cluster, bypass switches and control circuits, and a common bus capacitor;

[0081] The positive terminals of each battery cluster are connected to each other, serving as the positive terminals of the parallel battery clusters;

[0082] The positive terminal of each bus capacitor is connected to the negative terminal of the corresponding battery cluster.

[0083] The negative terminals of each bus capacitor are connected to each other, serving as the negative terminals of the parallel battery cluster;

[0084] The positive terminal of each bypass switch is connected to the positive terminal of the corresponding bus capacitor, and the negative terminal of each bypass switch is connected to the negative terminal of the corresponding bus capacitor.

[0085] The positive input terminal of each control circuit is connected to the positive terminal of the corresponding bus capacitor, and the negative input terminal of each control circuit is connected to the negative terminal of the corresponding bus capacitor.

[0086] The positive output terminals of each control circuit are interconnected and connected to the positive terminal of the common bus capacitor.

[0087] The negative output terminals of each control circuit are interconnected and connected to the negative terminal of the common bus capacitor.

[0088] Each control circuit can control the positive or negative voltage of the corresponding bus capacitor, thereby adjusting the current of the corresponding battery cluster.

[0089] Specifically, refer to Figure 1 As shown, the total number of battery clusters is m (m is a positive integer), and the battery clusters include the first battery cluster B1, the second battery cluster B2, ..., the m-th battery cluster B... m Battery clusters B1, B2, ..., B m The positive terminals are interconnected, serving as the positive terminals of the parallel battery cluster; the bus capacitors include the first bus capacitor C1, the second bus capacitor C2, ..., the m-th bus capacitor C... m Battery clusters B1, B2, ..., B m The negative terminals are respectively connected to the bus capacitors C1, C2, ..., C m Connect the positive terminals, and the bus capacitors C1, C2, ..., C m The negative terminals are interconnected to serve as the negative terminals of the parallel battery cluster; the control circuit includes the first control circuit, the second control circuit, ..., the m-th control circuit, and bus capacitors C1, C2, ..., C... m Each is connected to the common bus capacitor C0 through its corresponding control circuit; bypass switches M1, M2, ..., M m They are connected in parallel with the corresponding bus capacitors.

[0090] In one embodiment, multiple control circuits can be controlled to adjust the voltage of the common bus capacitor;

[0091] When the voltage of the bus capacitor is positive, the corresponding control circuit can adjust the magnitude of the positive voltage of the bus capacitor in a controlled manner.

[0092] When the voltage of the bus capacitor is negative, the corresponding control circuit can adjust the magnitude of the negative voltage of the bus capacitor.

[0093] In one embodiment, each control circuit can switch between bypass mode and access mode;

[0094] When the bypass switch is connected, the corresponding control circuit operates in bypass mode;

[0095] When the bypass switch is disconnected, the corresponding control circuit operates in access mode.

[0096] In one embodiment, each control circuit is a bidirectional full-bridge converter circuit, and its topology diagram is as follows: Figure 2 As shown, it includes: a full-bridge circuit, a first inductor, and a second inductor;

[0097] One end of the first inductor serves as the positive input terminal of the control circuit;

[0098] The other end of the first inductor is connected to a midpoint of the full-bridge circuit;

[0099] One end of the second inductor is connected to the negative input terminal of the control circuit;

[0100] The other end of the second inductor is connected to the other midpoint of the full-bridge circuit;

[0101] The positive terminal of the DC terminal of the full-bridge circuit is used as the positive output terminal of the control circuit;

[0102] The negative terminal of the DC terminal of the full-bridge circuit serves as the negative output terminal of the control circuit.

[0103] In one embodiment, each control circuit adjusts the voltage magnitude and the positive / negative value of the bus capacitor by controlling the switching transistors of the full-bridge circuit.

[0104] In one embodiment, a circulating current suppression method for a parallel battery cluster state control system is also provided, the flowchart of which is shown below. Figure 3 As shown, it includes:

[0105] S101: Collect the battery current, corresponding bus capacitor voltage, and common bus voltage of each battery cluster through sampling elements;

[0106] S102: Based on the battery current and corresponding bus capacitor voltage of each battery cluster, determine the operating mode of the corresponding control circuit, and obtain the battery current setpoint and common bus voltage setpoint for each battery cluster.

[0107] S103: Control the battery status of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage.

[0108] In one embodiment, S102 determines the operating mode of the corresponding control circuit based on the battery current of each battery cluster and the corresponding bus capacitor voltage, and obtains the battery current setpoint and the common bus voltage setpoint for each battery cluster, specifically including:

[0109] The average battery current is obtained by averaging the battery currents of all collected battery clusters.

[0110] If the difference between the battery current and the average battery current of the battery cluster is less than a certain difference, the corresponding control circuit is determined to be in bypass mode, and the other control circuits are determined to be in access mode.

[0111] The given value of the battery current for each battery cluster is determined as the average value of the battery current;

[0112] The absolute values ​​of the bus capacitor voltages corresponding to all battery clusters are sorted or compared, and the voltage setpoint of the common bus voltage is determined as the highest absolute value of the bus capacitor voltage.

[0113] In one embodiment, S103 controls the battery state of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage, specifically including:

[0114] If the control circuit operates in bypass mode, the corresponding bypass switch is connected, and all the switching transistors of the full-bridge circuit of the control circuit are disconnected.

[0115] If the control circuit operates in access mode, the bypass switch is opened, and the control circuit adjusts the battery current of the corresponding battery cluster to the battery current setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the voltage setpoint.

[0116] In one embodiment, the specific control block diagram is as follows: Figure 4 As shown, in S103, the control circuit adjusts the battery current of the corresponding battery cluster to the setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the setpoint, specifically including:

[0117] The common bus capacitor voltage setpoint is compared with the collected common bus capacitor voltage, and the result is passed through a proportional-integral regulator to obtain the common current reference value.

[0118] Divide the common current reference value by the number of control circuits operating in access mode, and add it to the battery current setpoint to obtain the actual battery current setpoint.

[0119] The actual given value of the battery current is compared with the battery current of the collected battery cluster. The result is passed through a proportional-integral regulator to obtain the duty cycle, which controls the switching of the switching transistors of the full-bridge circuit.

[0120] In one embodiment, a state-of-charge balancing method for a parallel battery cluster state control system is also provided, the flowchart of which is shown below. Figure 5 As shown, it includes:

[0121] S201: Collect the battery current, state of charge, corresponding bus capacitor voltage and common bus voltage of each battery cluster through sampling elements;

[0122] S202: Based on the battery current, state of charge, and corresponding bus capacitor voltage of each battery cluster, determine the operating mode of the corresponding control circuit, and obtain the battery current setpoint and the common bus voltage setpoint for each battery cluster.

[0123] S203: Control the battery status of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage.

[0124] In one embodiment, in step S202, the operating mode of the corresponding control circuit is determined based on the battery current, state of charge, and corresponding bus capacitor voltage of each battery cluster, and the given values ​​of the battery current and common bus voltage for each battery cluster are obtained. Specifically, this includes:

[0125] The average battery current is obtained by averaging the battery currents of all collected battery clusters.

[0126] The average state of charge (SOC) of all collected battery clusters is obtained by averaging the SOC values.

[0127] The given value of the battery current for each battery cluster is determined as the average value of the battery current;

[0128] The given battery current value for each battery cluster is calculated using the following relationship:

[0129]

[0130]

[0131] I refk =I avg +λ(SOC k -SOC avg )

[0132] Among them, I Batk The SOC represents the battery current, k = 1, ..., n, where k is the kth battery cluster. k λ represents the state of charge, and λ represents the adjustment parameter for the state of charge.

[0133] If the difference between the state of charge of the battery cluster and the given value of the battery current is less than a certain difference, the operating mode of the corresponding control circuit is determined to be bypass mode, and the operating mode of the other control circuits is determined to be access mode.

[0134] The absolute values ​​of the bus capacitor voltages corresponding to all battery clusters are sorted or compared, and the voltage setpoint of the common bus voltage is determined as the highest absolute value of the bus capacitor voltage.

[0135] In one embodiment, S203 controls the battery state of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage, specifically including:

[0136] If the control circuit operates in bypass mode, the corresponding bypass switch is connected, and all the switching transistors of the full-bridge circuit of the control circuit are disconnected.

[0137] If the control circuit operates in access mode, the bypass switch is opened, and the control circuit adjusts the battery current of the corresponding battery cluster to the battery current setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the voltage setpoint.

[0138] In one embodiment, the specific control block diagram is as follows: Figure 6 As shown, in S203, the control circuit adjusts the battery current of the corresponding battery cluster to the setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the setpoint, specifically including:

[0139] The common bus capacitor voltage setpoint is compared with the collected common bus capacitor voltage, and the result is passed through a proportional-integral regulator to obtain the common current reference value.

[0140] Divide the common current reference value by the number of control circuits operating in access mode, and add it to the battery current setpoint to obtain the actual battery current setpoint.

[0141] The actual given value of the battery current is compared with the battery current of the collected battery cluster. The result is passed through a proportional-integral regulator to obtain the duty cycle, which controls the switching of the switching transistors of the full-bridge circuit.

[0142] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A parallel battery cluster state control system, characterized in that, include: Multiple bus capacitors, bypass switches and control circuits corresponding to each battery cluster, and a common bus capacitor; The positive ends of the battery clusters are connected to each other to form the positive ends of the parallel battery clusters; The positive terminal of the bus capacitor is connected to the negative terminal of the corresponding battery cluster. The negative terminals of the bus capacitors are connected to each other to serve as the negative terminals of the parallel battery cluster. The positive terminal of the bypass switch is connected to the positive terminal of the corresponding bus capacitor, and the negative terminal of the bypass switch is connected to the negative terminal of the corresponding bus capacitor. The positive input terminal of the control circuit is connected to the positive terminal of the corresponding bus capacitor, and the negative input terminal of the control circuit is connected to the negative terminal of the corresponding bus capacitor. The positive output terminals of the control circuit are interconnected and connected to the positive terminal of the common bus capacitor. The negative output terminals of the control circuit are interconnected and connected to the negative terminal of the common bus capacitor. The control circuit can control the voltage of the corresponding bus capacitor, thereby adjusting the current of the corresponding battery cluster. Each of the control circuits is a bidirectional full-bridge converter circuit, comprising: a full-bridge circuit, a first inductor, and a second inductor; One end of the first inductor serves as the positive input terminal of the control circuit; The other end of the first inductor is connected to a midpoint of the full-bridge circuit; One end of the second inductor is connected to the negative input terminal of the control circuit; The other end of the second inductor is connected to the other midpoint of the full-bridge circuit; The positive terminal of the DC terminal of the full-bridge circuit serves as the positive output terminal of the control circuit. The negative terminal of the DC terminal of the full-bridge circuit serves as the negative output terminal of the control circuit. Each of the control circuits adjusts the voltage magnitude and the positive / negative value of the bus capacitor by controlling the switching transistors of the full-bridge circuit.

2. The parallel battery cluster state control system according to claim 1, characterized in that: The multiple control circuits are capable of controlling and adjusting the voltage of the common bus capacitor; When the voltage of the bus capacitor is positive, the corresponding control circuit can controllably adjust the magnitude of the positive voltage of the bus capacitor. When the voltage of the bus capacitor is negative, the corresponding control circuit can controllably adjust the magnitude of the negative voltage of the bus capacitor.

3. The parallel battery cluster state control system according to claim 1, characterized in that, Each of the control circuits can switch between bypass mode and access mode; When the bypass switch is connected, the corresponding control circuit operates in bypass mode; When the bypass switch is disconnected, the corresponding control circuit operates in access mode.

4. A circulating current suppression method for a parallel battery cluster state control system as described in any one of claims 1-3, comprising: S101: Collect the battery current, corresponding bus capacitor voltage, and common bus voltage of each battery cluster through sampling elements; S102: Based on the battery current and corresponding bus capacitor voltage of each battery cluster, determine the operating mode of the corresponding control circuit, and obtain the battery current setpoint and common bus voltage setpoint for each battery cluster. S103: Control the battery status of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage.

5. The circulating current suppression method for a parallel battery cluster state control system according to claim 4, characterized in that, In step S102, the operating mode of the corresponding control circuit is determined based on the battery current and the corresponding bus capacitor voltage of each battery cluster, and the battery current setpoint and the common bus voltage setpoint for each battery cluster are obtained. Specifically, this includes: The average battery current is obtained by averaging the battery currents of all collected battery clusters. If the difference between the battery current and the average battery current of the battery cluster is less than a certain difference, the corresponding control circuit is determined to be in bypass mode, and the other control circuits are determined to be in access mode. The given value of the battery current for each battery cluster is determined as the average value of the battery current; The absolute values ​​of the bus capacitor voltages corresponding to all battery clusters are sorted or compared, and the voltage setpoint of the common bus voltage is determined as the highest absolute value of the bus capacitor voltage.

6. The circulating current suppression method for a parallel battery cluster state control system according to claim 4, characterized in that, In step S103, the battery state of each battery cluster is controlled according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage, specifically including: If the operating mode of the control circuit is bypass mode, the corresponding bypass switch is connected, and all the switching transistors of the full-bridge circuit of the control circuit are disconnected. If the operating mode of the control circuit is the access mode, the bypass switch is opened, and the control circuit adjusts the battery current of the corresponding battery cluster to the battery current setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the voltage setpoint.

7. The circulating current suppression method for a parallel battery cluster state control system according to claim 6, characterized in that, In S103, the control circuit adjusts the battery current of the corresponding battery cluster to the given battery current value by controlling the switching transistor of the full-bridge circuit, and the parallel battery cluster status control system adjusts the common bus voltage to the given voltage value, specifically including: The common bus capacitor voltage setpoint is compared with the collected common bus capacitor voltage, and the result is passed through a proportional-integral regulator to obtain the common current reference value. Divide the common current reference value by the number of control circuits operating in access mode, and add it to the battery current setpoint to obtain the actual battery current setpoint. The actual given value of the battery current is compared with the battery current of the collected battery cluster. The result is passed through a proportional-integral regulator to obtain the duty cycle, which controls the switching of the switching transistors of the full-bridge circuit.

8. A method for state-of-charge balancing in a parallel battery cluster state control system as described in any one of claims 1-3, comprising: S201: Collect the battery current, state of charge, corresponding bus capacitor voltage and common bus voltage of each battery cluster through sampling elements; S202: Based on the battery current, state of charge, and corresponding bus capacitor voltage of each battery cluster, determine the operating mode of the corresponding control circuit, and obtain the battery current setpoint and the common bus voltage setpoint for each battery cluster. S203: Control the battery status of each battery cluster according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage.

9. The method for state-of-charge balancing in a parallel battery cluster state control system according to claim 8, characterized in that, In step S202, the operating mode of the corresponding control circuit is determined based on the battery current, state of charge, and corresponding bus capacitor voltage of each battery cluster, and the given values ​​of the battery current and common bus voltage for each battery cluster are obtained. Specifically, this includes: The average battery current is obtained by averaging the battery currents of all collected battery clusters. The average state of charge (SOC) of all collected battery clusters is obtained by averaging the SOC values. The given value of the battery current for each battery cluster is determined as the average value of the battery current; The given battery current value for each battery cluster is calculated using the following relationship: Among them, I Batk The SOC represents the battery current, k=1,…,n, representing the k-th battery cluster. k λ represents the state of charge, and λ represents the adjustment parameter for the state of charge. If the difference between the state of charge of the battery cluster and the given value of the battery current is less than a certain difference, the operating mode of the corresponding control circuit is determined to be bypass mode, and the operating mode of the other control circuits is determined to be access mode. The absolute values ​​of the bus capacitor voltages corresponding to all battery clusters are sorted or compared, and the voltage setpoint of the common bus voltage is determined as the highest absolute value of the bus capacitor voltage.

10. The method for state-of-charge balancing in a parallel battery cluster state control system according to claim 8, characterized in that, In step S203, the battery state of each battery cluster is controlled according to the operating mode of each control circuit, the battery current setpoint of each battery cluster, and the voltage setpoint of the common bus voltage, specifically including: If the operating mode of the control circuit is bypass mode, the corresponding bypass switch is connected, and all the switching transistors of the full-bridge circuit of the control circuit are disconnected. If the operating mode of the control circuit is the access mode, the bypass switch is opened, and the control circuit adjusts the battery current of the corresponding battery cluster to the battery current setpoint by controlling the switching transistor of the full-bridge circuit. The parallel battery cluster status control system adjusts the common bus voltage to the voltage setpoint.

11. The method for state-of-charge balancing in a parallel battery cluster state control system according to claim 10, characterized in that, In S203, the control circuit adjusts the battery current of the corresponding battery cluster to the given battery current value by controlling the switching transistor of the full-bridge circuit, and the parallel battery cluster status control system adjusts the common bus voltage to the given voltage value, specifically including: The common bus capacitor voltage setpoint is compared with the collected common bus capacitor voltage, and the result is passed through a proportional-integral regulator to obtain the common current reference value. Divide the common current reference value by the number of control circuits operating in access mode, and add it to the battery current setpoint to obtain the actual battery current setpoint. The actual given value of the battery current is compared with the battery current of the collected battery cluster. The result is passed through a proportional-integral regulator to obtain the duty cycle, which controls the switching of the switching transistors of the full-bridge circuit.

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