Multi-battery pack system, equalization method and control method of bidirectional direct current converter

Abstract

The invention discloses a multi-battery pack system, an equalization method and a control method, and each battery pack is provided with a switch unit and a bidirectional direct current converter, so that each battery pack is connected to an equalization bus through the switch unit and the bidirectional direct current converter. After entering the equalization state, the controller can firstly control the first switch unit corresponding to the first battery pack with the highest electric quantity and the second switch unit corresponding to the second battery pack with the lowest electric quantity to be switched on, and then control the first battery pack with the highest electric quantity to discharge to the equalization bus through the corresponding first bidirectional direct-current converter. And controlling the second battery pack with the lowest electric quantity to receive the voltage of the equalization bus through the corresponding second bidirectional direct-current converter for charging so as to realize the function that the first battery pack with the highest electric quantity performs active charging equalization on the second battery pack with the lowest electric quantity, thereby effectively solving the problem that the battery packs are unbalanced. The available capacity and the service life of the multi-battery pack system can be improved, and the system efficiency can be improved.

Description

Technical Field

[0001] This application relates to the technical field of energy storage, and particularly relates to a multi-battery-pack system, an equalization method, and a control method for a bidirectional DC converter. Background Art

[0002] In current energy storage devices, in order to achieve a large capacity, multiple battery packs are usually connected in series to form a multi-battery-pack system. Since the capacities and performances of individual battery packs may vary with the increase in usage time, ultimately the battery pack with the lowest capacity will limit the overall charging and discharging of the entire multi-battery-pack system, resulting in a reduction in the overall capacity and service life of the multi-battery-pack system. Summary of the Invention

[0003] In view of this, this application provides a multi-battery-pack system, an equalization method, and a control method for a bidirectional DC converter, which are used to effectively solve the problem of battery pack imbalance, are beneficial to improving the available capacity and service life of the multi-battery-pack system, and can improve system efficiency. The technical solutions of this application are as follows:

[0004] In a first aspect of this application, a multi-battery-pack system is provided, including at least two battery packs, at least two bidirectional DC converters, at least two switch units, and a controller; each battery pack is connected to one of the bidirectional DC converters through one of the switch units, and the bidirectional DC converter is connected to an equalization bus; the controller is connected to the battery packs, the bidirectional DC converters, and the switch units; the controller is configured to: obtain the power information of each battery pack; when it is determined according to the power information that the power difference between any battery packs is greater than a first preset difference, determine the first battery pack with the highest power and the second battery pack with the lowest power; control the first switch unit corresponding to the first battery pack to conduct, and send an equalization discharge instruction to the first bidirectional DC converter corresponding to the first battery pack, so that the first bidirectional DC converter operates in a discharge state according to the equalization discharge instruction; control the second switch unit corresponding to the second battery pack to conduct, and send an equalization charge instruction to the second bidirectional DC converter corresponding to the second battery pack, so that the second bidirectional DC converter operates in a charge state according to the equalization charge instruction; when the power difference between the first battery pack and the second battery pack is less than or equal to a second preset difference, control the first switch unit and the second switch unit to disconnect, and control the first bidirectional DC converter and the second bidirectional DC converter to stop working.

[0005] In an embodiment of the present application, the first bidirectional DC converter includes a first bidirectional DC conversion circuit and a first control circuit, and the second bidirectional DC converter includes a second bidirectional DC conversion circuit and a second control circuit; the first battery pack is connected to the first end of the first bidirectional DC conversion circuit through a first switch unit, and the second end of the first bidirectional DC conversion circuit is connected to the equalizing bus; the second battery pack is connected to the first end of the second bidirectional DC conversion circuit through a second switch unit, and the second end of the second bidirectional DC conversion circuit is connected to the equalizing bus; the first control circuit and the second control circuit are connected to a controller, and the first control circuit is configured to receive an equalizing discharge instruction and control the first bidirectional DC conversion circuit to operate in a discharge state according to the equalizing discharge instruction; the second control circuit is configured to receive an equalizing charge instruction and control the second bidirectional DC conversion circuit to operate in a charge state according to the equalizing charge instruction.

[0006] In an embodiment of the present application, after receiving the equalizing discharge instruction, the first control circuit is configured to: obtain the bus information of the equalizing bus in real time; generate a first driving signal according to the bus information; wherein, the first driving signal is used to drive the first bidirectional DC conversion circuit to operate in a discharge state.

[0007] In an embodiment of the present application, the first bidirectional DC conversion circuit is a resonant DAB conversion circuit; the first control circuit is configured to: obtain a first target phase shift angle according to the bus information; generate a first driving signal according to the first target phase shift angle.

[0008] In an embodiment of the present application, the bus information includes the bus voltage and the bus reference voltage of the equalizing bus, and correspondingly, the first target phase shift angle includes a first external phase shift angle; or the bus information includes the bus voltage, the bus current and the bus reference voltage of the equalizing bus, and correspondingly, the first target phase shift angle includes a first primary side internal phase shift angle, a first secondary side internal phase shift angle and a first external phase shift angle.

[0009] In an embodiment of the present application, after receiving the equalizing charge instruction, the second control circuit is configured to: obtain the bus information of the equalizing bus in real time, and the bus information includes the bus voltage of the equalizing bus; when the bus voltage reaches a preset voltage, obtain the battery information of the second battery pack in real time; generate a second driving signal according to the bus information and the battery information, or generate a second driving signal according to the battery information; wherein, the second driving signal is used to drive the second bidirectional DC conversion circuit to operate in a charge state.

[0010] In an embodiment of the present application, the second control circuit is configured to: obtain a second target phase shift angle according to the bus information and the battery information, or obtain a second target phase shift angle according to the battery information; generate a second driving signal according to the second target phase shift angle.

[0011] In an embodiment of the present application, the battery information includes the battery current and the current reference value of the second battery pack, or the battery information includes the battery power and the power reference value of the second battery pack; the bus information further includes the bus current of the equalization bus; the second target phase shift angle includes a second primary internal phase shift angle, a second secondary internal phase shift angle, and a second external phase shift angle.

[0012] A second aspect of the present application provides an equalization method for a multi-battery pack system. The multi-battery pack system includes at least two battery packs, at least two bidirectional DC converters, and at least two switch units; each battery pack is connected to one of the bidirectional DC converters through one of the switch units, and the bidirectional DC converter is connected to the equalization bus; the equalization method includes: obtaining the power information of each battery pack; when it is determined according to the power information that the power difference between any two battery packs is greater than a first preset difference, determining the first battery pack with the highest power and the second battery pack with the lowest power; controlling the first switch unit corresponding to the first battery pack to conduct, and sending an equalization discharge instruction to the first bidirectional DC converter corresponding to the first battery pack, so that the first bidirectional DC converter operates in a discharge state according to the equalization discharge instruction; controlling the second switch unit corresponding to the second battery pack to conduct, and sending an equalization charge instruction to the second bidirectional DC converter corresponding to the second battery pack, so that the second bidirectional DC converter operates in a charge state according to the equalization charge instruction; when the power difference between the first battery pack and the second battery pack is less than or equal to a second preset difference, controlling the first switch unit and the second switch unit to disconnect, and controlling the first bidirectional DC converter and the second bidirectional DC converter to stop working.

[0013] A third aspect of the present application provides a control method for a bidirectional DC converter. The bidirectional DC converter is applied to a multi-battery pack system, and one end of the bidirectional DC converter is connected to one of the battery packs through one of the switch units in the multi-battery pack system, and the other end of the bidirectional DC converter is connected to the equalization bus in the multi-battery pack system; the control method includes: when receiving an equalization discharge instruction, obtaining the bus information of the equalization bus in real time; wherein, the bus information includes the bus voltage of the equalization bus; generating a first driving signal according to the bus information; wherein, the first driving signal is used to drive the bidirectional DC converter to operate in a discharge state; when receiving an equalization charge instruction, obtaining the bus information in real time; when the bus voltage reaches a preset voltage, obtaining the battery information of the corresponding battery pack in real time;

[0014] Generating a second driving signal according to the bus information and the battery information, or generating a second driving signal according to the battery information; wherein, the second driving signal is used to drive the bidirectional DC converter to operate in a charge state.

[0015] In an embodiment of the present application, generating a first driving signal according to the bus information includes: obtaining a first target phase shift angle according to the bus information; generating a first driving signal according to the first target phase shift angle.

[0016] In an embodiment of the present application, the bus information further includes the bus reference voltage of the equalizing bus, and the first target phase shift angle includes a first external phase shift angle; obtaining the first target phase shift angle according to the bus information includes: obtaining the first external phase shift angle according to the difference between the bus voltage and the bus reference voltage; correspondingly, generating a first drive signal according to the first target phase shift angle includes: generating a first drive signal according to the first external phase shift angle.

[0017] In an embodiment of the present application, the bus information further includes the bus current and the bus reference voltage of the equalizing bus, and the first target phase shift angle includes a first primary internal phase shift angle, a first secondary internal phase shift angle, and a first external phase shift angle; obtaining the first target phase shift angle according to the bus information includes: obtaining the first primary internal phase shift angle, the first secondary internal phase shift angle, and a first initial external phase shift angle according to the bus voltage and the bus current; obtaining a first compensation phase shift angle according to the bus voltage and the bus reference voltage; compensating the first initial external phase shift angle with the first compensation phase shift angle to obtain the first external phase shift angle; correspondingly, generating a first drive signal according to the first target phase shift angle includes: generating a first drive signal according to the first primary internal phase shift angle, the first secondary internal phase shift angle, and the first external phase shift angle.

[0018] In an embodiment of the present application, obtaining the first primary internal phase shift angle, the first secondary internal phase shift angle, and the first initial external phase shift angle according to the bus voltage and the bus current includes: calculating the normalized bus-side power according to the bus voltage and the bus current, and calculating the resonant cavity gain according to the bus voltage; when the resonant cavity gain is less than or equal to 1 and the absolute value of the normalized bus-side power is less than or equal to the first bus power boundary value, calculating the first primary internal phase shift angle and the first initial external phase shift angle according to the normalized bus-side power and the resonant cavity gain; wherein, the first secondary internal phase shift angle is 0; when the resonant cavity gain is less than or equal to 1 and the absolute value of the normalized bus-side power is greater than the first bus power boundary value, calculating the first initial external phase shift angle according to the normalized bus-side power; wherein, the first primary internal phase shift angle and the first secondary internal phase shift angle are 0; when the resonant cavity gain is greater than 1 and the absolute value of the normalized bus-side power is less than or equal to the second bus power boundary value, calculating the first secondary internal phase shift angle and the first initial external phase shift angle according to the normalized bus-side power and the resonant cavity gain; wherein, the first primary internal phase shift angle is 0; when the resonant cavity gain is greater than 1 and the absolute value of the normalized bus-side power is greater than the second bus power boundary value, calculating the first initial external phase shift angle according to the normalized bus-side power; wherein, the first primary internal phase shift angle and the first secondary internal phase shift angle are 0.

[0019] In an embodiment of the present application, generating a second drive signal according to the bus information and the battery information, or generating a second drive signal according to the battery information includes: obtaining a second target phase shift angle according to the bus information and the battery information, or obtaining a second target phase shift angle according to the battery information; generating a second drive signal according to the second target phase shift angle.

[0020] In an embodiment of the present application, the battery information includes the battery current and the current reference value of the corresponding battery pack, and the second target phase shift angle includes a second external phase shift angle; obtaining the second target phase shift angle according to the battery information includes: obtaining the second external phase shift angle according to the battery current and the current reference value; correspondingly, generating a second drive signal according to the second target phase shift angle includes: generating a second drive signal according to the second external phase shift angle.

[0021] In an embodiment of the present application, the bus information further includes the bus current of the equalizing bus, the battery information includes the battery current and the current reference value of the corresponding battery pack, and the second target phase shift angle includes a second primary-side internal phase shift angle, a second secondary-side internal phase shift angle, and a second external phase shift angle; obtaining the second target phase shift angle according to the bus information and the battery information includes: obtaining the second primary-side internal phase shift angle, the second secondary-side internal phase shift angle, and a second initial external phase shift angle according to the bus voltage and the bus current; obtaining a second compensation phase shift angle according to the battery current and the current reference value; compensating the second initial external phase shift angle with the second compensation phase shift angle to obtain the second external phase shift angle; correspondingly, generating a second drive signal according to the second target phase shift angle includes: generating a second drive signal according to the second primary-side internal phase shift angle, the second secondary-side internal phase shift angle, and the second external phase shift angle.

[0022] In an embodiment of the present application, the bus information further includes the bus current of the equalizing bus, the battery information includes the battery power and the power reference value of the corresponding battery pack, and the second target phase shift angle includes a second primary-side internal phase shift angle, a second secondary-side internal phase shift angle, and a second external phase shift angle; obtaining the second target phase shift angle according to the bus information and the battery information includes: obtaining the second primary-side internal phase shift angle, the second secondary-side internal phase shift angle, and a second initial external phase shift angle according to the bus voltage and the bus current; obtaining a second compensation phase shift angle according to the battery power and the power reference value; compensating the second initial external phase shift angle with the second compensation phase shift angle to obtain the second external phase shift angle; correspondingly, generating a second drive signal according to the second target phase shift angle includes: generating a second drive signal according to the second primary-side internal phase shift angle, the second secondary-side internal phase shift angle, and the second external phase shift angle.

[0023] In the multi - battery - pack system according to the embodiments of the present application, by setting a switching unit and a bidirectional DC - DC converter for each battery pack, each battery pack is connected to the equalization bus through the switching unit and the bidirectional DC - DC converter. After entering the equalization state, the controller can first control the first switching unit corresponding to the first battery pack with the highest power and the second switching unit corresponding to the second battery pack with the lowest power to conduct, and then control the first battery pack with the highest power to discharge to the equalization bus through the corresponding first bidirectional DC - DC converter, and control the second battery pack with the lowest power to receive the voltage of the equalization bus through the corresponding second bidirectional DC - DC converter for charging, so as to achieve the function of the first battery pack with the highest power actively charging and equalizing the second battery pack with the lowest power, thereby effectively solving the problem of battery - pack imbalance, being beneficial to improving the available capacity and service life of the multi - battery - pack system, and being able to improve the system efficiency. Description of the Drawings

[0024] Figure 1 is a schematic block diagram of a multi - battery - pack system provided by an embodiment of the present application.

[0025] Figure 2 is a schematic block diagram of a second multi - battery - pack system provided by an embodiment of the present application.

[0026] Figure 3 is a schematic circuit diagram of the bidirectional DC - DC converter provided by an embodiment of the present application.

[0027] Figure 4 is a specific control block diagram of the first control circuit controlling the first bidirectional DC - DC conversion circuit to work in the discharging state in a specific example of the present application.

[0028] Figure 5 is a specific control block diagram of the first control circuit controlling the first bidirectional DC - DC conversion circuit to work in the discharging state in another specific example of the present application.

[0029] Figure 6 is a specific control block diagram of the second control circuit controlling the second bidirectional DC - DC conversion circuit to work in the charging state in a specific example of the present application.

[0030] Figure 7 is a specific control block diagram of the second control circuit controlling the second bidirectional DC - DC conversion circuit to work in the charging state in another specific example of the present application.

[0031] Figure 8 is a specific control block diagram of the second control circuit controlling the second bidirectional DC - DC conversion circuit to work in the charging state in yet another specific example of the present application.

[0032] Figure 9 is a schematic flow diagram of an equalization method provided by an embodiment of the present application.

[0033] Figure 10 It is a schematic flowchart of a control method provided by an embodiment of the present application.

[0034] Figure 11 It is Figure 10 a refined flowchart of step S200 in

[0035] Figure 12 It is Figure 11 a refined flowchart of step S210 in

[0036] Figure 13 It is Figure 12 a refined flowchart of step S211 in

[0037] Figure 14 It is Figure 10 a refined flowchart of step S500 in

[0038] Figure 15 It is Figure 14 a refined flowchart of step S510 in

[0039] Figure 16 It is a refined flowchart of step S510 in another specific example of the present application. Detailed implementation manners

[0040] It should be noted that in the embodiments of the present application, "at least one" means one or more, and "a plurality" means two or more than two. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims, and drawings of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0041] In addition, it should be noted that for the methods disclosed in the embodiments of the present application or shown in the flowcharts, including one or more steps for implementing the methods, without departing from the scope of the claims, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0042] Please refer to Figure 1 , Figure 1 which is a schematic block diagram of a multi-battery-pack system provided by an embodiment of the present application. Among them, the multi-battery-pack system 100 includes: at least two battery packs 110, at least two bidirectional DC converters 120, at least two switch units 130, and a controller 140.

[0043] Among them, each battery pack 110 is connected to one of the bidirectional DC converters 120 through one of the switch units 130, and the bidirectional DC converter 120 is connected to the equalization bus. The controller 140 is connected to the battery pack 110, the bidirectional DC converter 120, and the switch unit 130.

[0044] In the embodiment of the present application, at least two battery packs 110 can be connected in series to the bus (not shown in the figure) of the multi-battery pack system 100, so as to be connected to a power converter (not shown in the figure) through the bus and supply power to the load connected to the power converter, or the battery packs 110 can be charged by the power grid connected to the power converter. Alternatively, at least two battery packs 110 can also be connected in parallel to the bus of the multi-battery pack system 100.

[0045] In the embodiment of the present application, the controller 140 can be used to obtain the power information of each battery pack 110. When it is determined according to the power information that the power difference between any two battery packs 110 is greater than a first preset difference, the first battery pack with the highest power and the second battery pack with the lowest power are determined. Furthermore, the controller 140 controls the first switch unit corresponding to the first battery pack to turn on, and sends an equalization discharge instruction to the first bidirectional DC converter corresponding to the first battery pack, so that the first bidirectional DC converter operates in a discharge state according to the equalization discharge instruction.

[0046] Moreover, the controller 140 controls the second switch unit corresponding to the second battery pack to turn on. Thus, a series system is formed between the first battery pack and the second battery pack. The controller 140 also sends an equalization charge instruction to the second bidirectional DC converter corresponding to the second battery pack, so that the second bidirectional DC converter operates in a charge state according to the equalization charge instruction.

[0047] In this way, when the power difference between any two battery packs 110 is greater than the first preset difference, the controller 140 enters the equalization state. The controller 140 can control two of the battery packs 110 to perform mutual charge equalization, that is, the battery pack 110 with the highest power can be used to charge the battery pack 110 with the lowest power. Therefore, after entering the equalization state, the controller 140 can also sort according to the power of each battery pack 110. For example, after sorting the powers from largest to smallest, the highest power and the lowest power are determined to determine the above-mentioned first battery pack and second battery pack. Among them, the multi-battery pack system 100 can also enter the above-mentioned equalization state during the normal charging or discharging working state. In the equalization state, the first battery pack and the second battery pack may not participate in the normal discharging or charging work of the multi-battery pack system 100, or the first battery pack and the second battery pack may not participate in the normal discharging or charging work of the multi-battery pack system 100 during the equalization process at the same time, which is not limited here.

[0048] When the power difference between the first battery pack and the second battery pack is less than or equal to the second preset difference, the controller 140 controls the first switch unit and the second switch unit to disconnect, and controls the first bidirectional DC converter and the second bidirectional DC converter to stop working, completing the balancing between the first battery pack and the second battery pack.

[0049] It can be understood that the first preset difference and the second preset difference can be the same value or different values. When they are different values, the second preset difference is less than the first preset difference. The first preset difference and the second preset difference can be set according to the requirements for the power difference between battery packs in the multi-battery pack system.

[0050] Among them, the battery pack 110 includes a battery cell unit and a battery management unit. The battery cell unit is used to store electrical energy, and the battery management unit is used to collect the working information of the battery cell unit. For example, the battery management unit can collect the voltage value, temperature, and SOC value (SOC, State of charge) of the battery cell unit in real time. The above-mentioned controller 140 can be a programmable microprocessor and its peripheral circuits, and is connected to the battery management unit of each battery pack 110 through a communication line to obtain data such as the SOC value and voltage value of the battery pack 110 in real time as power information. Thus, the controller 140 can monitor the SOC difference between each battery pack 110, that is, the power difference between each battery pack 110, and execute the above steps when it is determined that the SOC difference between any battery packs 110 is greater than the preset difference. For example, when the controller 140 monitors that the SOC difference between any two battery packs 110 is greater than 5, it starts to execute the above steps. Among them, in this example, the value range of the SOC value of the battery pack 110 is from 0 to 100. In addition, the controller 140 can also be communicatively connected to each bidirectional DC converter 120 to send a balancing discharge instruction or a balancing charge instruction to the bidirectional DC converter 120.

[0051] It can be understood that in the embodiments of the present application, by providing a switching unit 130 and a bidirectional DC converter 120 for each battery pack 110, each battery pack 110 is connected to the equalization bus through the switching unit 130 and the bidirectional DC converter 120. After entering the equalization state, the controller 140 can first control the first switching unit corresponding to the first battery pack with the maximum SOC value and the second switching unit corresponding to the second battery pack with the minimum SOC value to conduct, and then control the first battery pack with the maximum SOC value to discharge to the equalization bus through the corresponding first bidirectional DC converter, and control the second battery pack with the minimum SOC value to receive the voltage of the equalization bus through the corresponding second bidirectional DC converter to charge, so as to realize the function of the first battery pack with the maximum SOC value actively charging and equalizing the second battery pack with the minimum SOC value, thereby effectively solving the problem of imbalance of the battery packs 110, being beneficial to improving the available capacity and service life of the multi-battery pack system 100, and capable of improving the system efficiency. Moreover, during the equalization process, the power of the first battery pack and the second battery pack undergoing equalization is also monitored in real time. The equalization process continues only when the power difference between the first battery pack and the second battery pack is greater than the second preset difference. When the power difference between the first battery pack and the second battery pack is less than or equal to the second preset difference, the first switching unit and the second switching unit are controlled to disconnect, and the first bidirectional DC converter and the second bidirectional DC converter are controlled to stop working, completing the equalization between the first battery pack and the second battery pack.

[0052] In some embodiments, as Figure 2 shown, each bidirectional DC converter 120 may include a bidirectional DC conversion circuit 121 and a control circuit 122. The battery pack 110 is connected to the first end of the bidirectional DC conversion circuit 121 through the switching unit 130. The second end of the bidirectional DC conversion circuit 121 is connected to the equalization bus, and the control circuit 122 is connected to the controller 140 and the bidirectional DC conversion circuit 121. When the control circuit 122 receives the equalization discharge instruction sent by the controller 140, it controls the bidirectional DC conversion circuit 121 to operate in the discharge state according to the equalization discharge instruction. When the control circuit 122 receives the equalization charge instruction sent by the controller 140, it controls the bidirectional DC conversion circuit 121 to operate in the charge state according to the equalization charge instruction.

[0053] Specifically, the first bidirectional DC converter includes a first bidirectional DC conversion circuit and a first control circuit, and the second bidirectional DC converter includes a second bidirectional DC conversion circuit and a second control circuit. The first control circuit is configured to receive an equalizing discharge instruction and control the first bidirectional DC conversion circuit to operate in a discharge state according to the equalizing discharge instruction; the second control circuit is configured to receive an equalizing charge instruction and control the second bidirectional DC conversion circuit to operate in a charge state according to the equalizing charge instruction. Thus, the first battery pack discharges to the equalizing bus through the first switch unit and the first bidirectional DC conversion circuit, and the second battery pack receives the voltage on the equalizing bus through the second bidirectional DC conversion circuit and the second switch unit for charging.

[0054] Among them, after receiving the equalizing discharge instruction, the first control circuit real-time obtains the bus information of the equalizing bus and generates a first driving signal according to the bus information. The first control circuit sends the first driving signal to the first bidirectional DC conversion circuit to drive the first bidirectional DC conversion circuit to operate in a discharge state.

[0055] In some embodiments, the bus information may include the bus voltage and the bus reference voltage of the equalizing bus, and the first control circuit may generate the first driving signal according to the bus voltage loop.

[0056] In some embodiments, such as Figure 3As shown, the switch unit 130 may include two controllable switches. Specifically, the controllable switches may be relays, namely a positive relay K1 and a negative relay K2. The bidirectional DC conversion circuit 121 may be a resonant DAB conversion circuit. Based on this, the bidirectional DC conversion circuit 121 includes a first switch tube S1, a second switch tube S2, a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5, a sixth switch tube S6, a seventh switch tube S7, an eighth switch tube S8, a battery capacitor C1, a resonant capacitor Cr, a resonant inductor Lr, a transformer T, and a bus capacitor C2. The first end of the first switch tube S1 is connected to the positive pole of the battery pack 110 through the positive relay K1. The second end of the first switch tube S1 is connected to the first end of the second switch tube S2. The second end of the second switch tube S2 is connected to the negative pole of the battery pack 110 through the negative relay K2. And the battery capacitor C1 is connected between the positive and negative poles of the battery pack 110. The first end of the third switch tube S3 is connected to the first end of the first switch tube S1. The second end of the third switch tube S3 is connected to the first end of the fourth switch tube S4. The second end of the fourth switch tube S4 is connected to the second end of the second switch tube S2. The first end of the fifth switch tube S5 is connected to the first end of the seventh switch tube S7. The second end of the fifth switch tube S5 is connected to the first end of the sixth switch tube S6. The second end of the seventh switch tube S7 is connected to the first end of the eighth switch tube S8. The second end of the eighth switch tube S8 is connected to the second end of the sixth switch tube S6. The first end of the resonant capacitor Cr is connected to the second end of the first switch tube S1. The second end of the resonant capacitor Cr is connected to the first end of the resonant inductor Lr. The second end of the resonant inductor Lr is connected to the first end of the primary side of the transformer T. The second end of the primary side of the transformer T is connected to the second end of the third switch tube S3. The first end of the secondary side of the transformer T is connected to the second end of the fifth switch tube S5. The second end of the secondary side of the transformer T is connected to the second end of the seventh switch tube S7. The bus capacitor C2 is connected between the first end of the seventh switch tube S7 and the second end of the eighth switch tube S8 and is connected to the equalizing bus.

[0057] Based on this, after the controller 140 confirms the first battery pack and the second battery pack, it can control the two relays in the first switch unit to conduct, and control the two relays in the second switch unit to conduct. After receiving the equalizing discharge instruction, the first control circuit 122 can obtain the bus information of the equalizing bus in real time, and obtain the first target phase shift angle according to the bus information, and then generate a first driving signal according to the first target phase shift angle.

[0058] Among them, the first control circuit 122 can output the voltage of the first battery pack to the equalizing bus through phase shift control and bus voltage loop control of the first bidirectional DC conversion circuit 121.

[0059] In a specific example, the bus information may include the bus voltage and the bus reference voltage of the equalizing bus, and the first target phase shift angle may include a first external phase shift angle Dssa Correspondingly, after receiving the equalizing discharge instruction, the first control circuit 122 can obtain the bus voltage and the bus reference voltage of the equalizing bus in real time, and then obtain the first external phase shift angle D according to the difference between the bus voltage and the bus reference voltage. ssa Then, according to the first external phase shift angle D ssa a first drive signal is generated. Among them, the first external phase shift angle D ssa refers to the phase shift angle between the first switch tube S1 and the fifth switch tube S5 in the first bidirectional DC conversion circuit 121.

[0060] In this example, the first control circuit 122 controls the first bidirectional DC conversion circuit 121 through the bus voltage loop and the single phase shift control.

[0061] Please refer to Figure 4 , Figure 4 which shows the specific control block diagram of the first control circuit controlling the first bidirectional DC conversion circuit to work in the discharge state in this example. As Figure 4 shown, the first control circuit includes a first subtractor 141a, a first PI (Proportional Integral) controller 142a, a first phase shifter 143a, and a first pulse width modulator 144a. When the first control circuit receives the equalizing discharge instruction, the first subtractor 141a subtracts the bus reference voltage Vbus_Ref from the bus voltage Vbus to obtain a voltage deviation value. The first PI controller 142a performs deviation adjustment on the voltage deviation value to obtain a voltage compensation value. The first phase shifter 143a calculates the voltage compensation value to obtain the first external phase shift angle Dssa. The first pulse width modulator 144a modulates according to the first external phase shift angle Dssa to generate a first drive signal. It can be understood that the first drive signal is a PWM control signal, which is used to control the on and off of the first switch tube S1, the second switch tube S2, the third switch tube S3, the fourth switch tube S4, the fifth switch tube S5, the sixth switch tube S6, the seventh switch tube S7, and the eighth switch tube S8 of the first bidirectional DC conversion circuit, so that the voltage output by the first bidirectional DC conversion circuit to the equalizing bus can reach the bus reference voltage Vbus_Ref. Thus, the first control circuit uses the bus voltage Vbus of the equalizing bus as the control object, and establishes the bus voltage Vbus of the equalizing bus through the bus voltage Vbus loop and the single phase shift control, which can realize the stable output of the first bidirectional DC conversion circuit and the control method is simple.

[0062] Of course, the control method of the first control circuit for the first DC conversion circuit in the embodiment of the present application is not limited to this.

[0063] For example, in another specific example, the bus information may further include the bus current I_bus of the equalizing bus, and the first target phase shift angle includes the first primary internal phase shift angle Dpa 1. The first secondary internal phase-shift angle D sa and the first external phase-shift angle D ssa . Correspondingly, after receiving the equalizing discharge instruction, the first control circuit can obtain the bus voltage Vbus and the bus current I_bus of the equalizing bus in real time. Then, based on the bus voltage Vbus and the bus current I_bus, the first primary internal phase-shift angle D pa , the first secondary internal phase-shift angle D sa and the first initial external phase-shift angle D ssa1 are obtained. Then, based on the bus voltage Vbus and the bus reference voltage Vbus_Ref, the first compensation phase-shift angle D ssa2 is obtained. Using the first compensation phase-shift angle D ssa2 to compensate the first initial external phase-shift angle D ssa1 to obtain the first external phase-shift angle D ssa . Finally, based on the first primary internal phase-shift angle D pa , the first secondary internal phase-shift angle D sa and the first external phase-shift angle D ssa , the first drive signal is generated. Among them, the first primary internal phase-shift angle D pa refers to the phase-shift angle between the first switch tube S1 and the fourth switch tube S4 in the first bidirectional DC conversion circuit. The first secondary internal phase-shift angle D sa refers to the phase-shift angle between the fifth switch tube S5 and the eighth switch tube S8 in the first bidirectional DC conversion circuit. The first external phase-shift angle D ssa refers to the phase-shift angle between the first switch tube S1 and the fifth switch tube S5 in the first bidirectional DC conversion circuit.

[0064] In this example, the first control circuit controls the first bidirectional DC conversion circuit through a bus voltage loop and triple phase-shift (TPS) control.

[0065] Please refer to Figure 5 , Figure 5 , which shows the specific control block diagram of the first control circuit controlling the first bidirectional DC conversion circuit to work in the discharge state in this example. As Figure 5 shown, the first control circuit includes a first subtractor 141a, a first PI (Proportional Integral) controller 142a, a first phase shifter 143a, a first TPS controller 145a, a first adder 146a and a first pulse width modulator 144a. When the first control circuit receives the equalizing discharge instruction, the first subtractor 141a subtracts the bus reference voltage Vbus_Ref from the bus voltage Vbus to obtain a voltage deviation value. The first PI controller 142a performs deviation adjustment on the voltage deviation value to obtain a voltage compensation value. The first phase shifter 143a calculates the voltage compensation value to obtain the first compensation phase-shift angle D ssa2. The first TPS controller 145a calculates the first primary internal phase shift angle D based on the bus voltage Vbus and the bus current I_bus. pa , the first secondary internal phase shift angle D sa and the first initial external phase shift angle D ssa1 . The first adder 146a adds the first initial external phase shift angle D ssa1 and the first compensation phase shift angle D ssa2 to obtain the first external phase shift angle D ssa . The first pulse width modulator 144a modulates according to the first primary internal phase shift angle D pa , the first secondary internal phase shift angle D sa and the first external phase shift angle D ssa to generate the first drive signal.

[0066] In this example, the first TPS controller 145a can calculate a set of optimal internal and external phase shift angle solutions (i.e., the first primary internal phase shift angle D pa , the first secondary internal phase shift angle D sa and the first external phase shift angle D ssa ) that minimize the effective value of the resonant cavity current based on the bus voltage Vbus and the bus current I_bus of the balanced bus. The bus voltage Vbus loop compensates according to the error between the bus voltage Vbus and the bus reference voltage Vbus_Ref to ensure the dynamic performance of the loop and ensure the establishment and maintenance of the bus voltage Vbus. By minimizing the effective value of the resonant cavity current, the first TPS controller 145a can reduce the conduction loss and thus improve the efficiency.

[0067] Specifically, the first TPS controller 145a calculates the effective value of the resonant cavity current of the first bidirectional DC-DC converter circuit and the per-unitized expression of the average output power P bus.pu on the secondary side according to the fundamental wave analysis method:

[0068]

[0069] Among them, M is the resonant cavity gain of the first bidirectional DC-DC converter circuit, N is the turns ratio of the transformer T in the first bidirectional DC-DC converter circuit, and V1 is the input voltage of the first bidirectional DC-DC converter circuit, that is, the voltage provided by the first battery pack to the first bidirectional DC-DC converter circuit.

[0070] With the minimum effective value of the resonant cavity current as the optimization goal, a Lagrangian equation is constructed to convert the problem of optimizing and solving the phase shift angle into the problem of solving the extreme value of a multi-variable function, and the following formula is obtained:

[0071]

[0072] Among them, p is the normalized bus-side power, and -1 ≤ p ≤ 1. Finally, through mathematical solution, it can be obtained that:

[0073] When M ≤ 1,

[0074]

[0075] And when M > 1,

[0076]

[0077] Combined with the above formulas, the first TPS controller 145a receives the bus voltage Vbus and the bus current I_bus, and then calculates the normalized bus-side power p according to the bus voltage Vbus and the bus current I_bus, and calculates the resonant cavity gain M according to the bus voltage Vbus. When the resonant cavity gain M ≤ 1, it is judged whether the absolute value of the normalized bus-side power p is less than or equal to the first bus power boundary value. If the absolute value of the normalized bus-side power p is less than or equal to the first bus power boundary value, the first primary-side internal phase shift angle D pa and the first initial external phase shift angle D ssa1 are calculated according to the above formula (1), while the first secondary-side internal phase shift angle D sa is 0. If the absolute value of the normalized bus-side power p is greater than the first bus power boundary value, the first initial external phase shift angle D ssa1 is calculated according to the above formula (2), while the first primary-side internal phase shift angle D pa and the first secondary-side internal phase shift angle D sa are 0. Among them, the first bus power boundary value is the absolute value of (1 - M 2 ) in the above formula (1) and formula (2).

[0078] When the resonant cavity gain M > 1, it also first judges whether the absolute value of the normalized bus-side power p is less than or equal to the second bus power boundary value. If the absolute value of the normalized bus-side power p is less than or equal to the second bus power boundary value, the first secondary-side internal phase shift angle D sa and the first initial external phase shift angle D ssa1 are calculated according to the above formula (3), while the first primary-side internal phase shift angle D pa is 0. If the absolute value of the normalized bus-side power p is greater than the second bus power boundary value, the first initial external phase shift angle D ssa1 is calculated according to the above formula (4), while the first primary-side internal phase shift angle D pa and the first secondary-side internal phase shift angle D sa are 0. Among them, the second bus power boundary value is the absolute value of in the above formula (3) and formula (4).

[0079] Thus, the phase-shift control of the first bidirectional resonant conversion circuit is realized.

[0080] In some embodiments, after receiving the equalizing charge command, the second control circuit can obtain the bus information of the equalizing bus in real time. When the bus voltage reaches the preset voltage, the second control circuit obtains the battery information of the second battery pack in real time, and the second control circuit generates a second driving signal according to the bus information and the battery information, or generates a second driving signal according to the battery information. Wherein, the second driving signal is used to drive the second bidirectional DC conversion circuit to work in the charging state.

[0081] In this embodiment, after receiving the equalizing charge command, the second control circuit drives the second bidirectional DC conversion circuit only when the bus voltage reaches the preset voltage, so that the second bidirectional DC conversion circuit charges the second battery pack after the bus voltage of the equalizing bus is established, enabling the stable flow of energy between the first battery pack and the second battery pack. When the second control circuit receives the equalizing charge command but the bus voltage does not reach the preset voltage, the second control circuit does not control the second bidirectional DC conversion circuit to operate. In this embodiment, the preset voltage can be set according to the actual performance.

[0082] Based on the bidirectional DC conversion circuit 121 being a resonant DAB conversion circuit, the second control circuit can obtain a second target phase-shift angle according to the bus information and the battery information, and then generate a second driving signal according to the second target phase-shift angle.

[0083] Wherein, the second control circuit can output the voltage on the equalizing bus to the second battery pack through phase-shift control and battery current loop control to charge the second battery pack.

[0084] In a specific example, the battery information includes the battery current I_Pack and the current reference value I_Pack_Ref of the second battery pack. The second target phase-shift angle may include a second external phase-shift angle D ssb . Correspondingly, after receiving the equalizing charge command, the second control circuit can obtain the battery current I_Pack of the second battery pack in real time, and then obtain the second external phase-shift angle D according to the difference between the battery current I_Pack and the current reference value I_Pack_Ref ssb , and then generate a second driving signal according to the second external phase-shift angle D ssb . Wherein, the second external phase-shift angle D ssb refers to the phase-shift angle between the first switch tube S1 and the fifth switch tube S5 in the second bidirectional DC conversion circuit.

[0085] In this example, the second control circuit controls the second bidirectional DC conversion circuit through the battery current I_Pack loop and single phase-shift control.

[0086] Please refer to Figure 6 , Figure 6 which shows the specific control block diagram of the second control circuit controlling the second bidirectional DC conversion circuit to operate in the charging state in this example. As Figure 6 shown, the second control circuit includes a second subtractor 141b, a second PI controller 142b, a second phase shifter 143b, and a second pulse width modulator 144b. When the second control circuit receives the equalization charging instruction and the bus voltage Vbus reaches the preset voltage, the second subtractor 141b subtracts the current reference value I_Pack_Ref from the battery current I_Pack to obtain the current deviation value. The second PI controller 142b performs deviation adjustment on the current deviation value to obtain the current compensation value. The second phase shifter 143b calculates the current compensation value to obtain the second external phase shift angle D ssb , and the second pulse width modulator 144b performs modulation according to the second external phase shift angle D ssb to generate the second drive signal. It can be understood that the second drive signal is a PWM control signal, which is used to control the on and off of the first switch tube S1, the second switch tube S2, the third switch tube S3, the fourth switch tube S4, the fifth switch tube S5, the sixth switch tube S6, the seventh switch tube S7, and the eighth switch tube S8 of the second bidirectional DC conversion circuit, so that the second bidirectional DC conversion circuit can stably charge the second battery pack with the voltage on the equalization bus. Thus, the second control circuit takes the battery current I_Pack as the control object, and charges the second battery pack through the battery current I_Pack loop and single-phase shift control, which can adjust the power level in the series system formed by the first battery pack and the second battery pack, and can realize the stable power supply of the second bidirectional DC conversion circuit to the second battery pack and the control method is simple.

[0087] Of course, the control method of the second control circuit for the second DC conversion circuit in the embodiment of the present application is not limited to this.

[0088] For example, in another specific example, the bus information may further include the bus current I_bus of the equalization bus, the battery information includes the battery current I_Pack and the current reference value I_Pack_Ref of the second battery pack, and the second target phase shift angle includes the second primary side internal phase shift angle D pb , the second secondary side internal phase shift angle D sb , and the second external phase shift angle D ssb . Correspondingly, after receiving the equalization charging instruction, when the bus voltage Vbus reaches the preset voltage, the second control circuit can obtain the bus voltage Vbus, the bus current I_bus of the equalization bus, and the battery current I_Pack of the second battery pack in real time. Furthermore, according to the bus voltage Vbus and the bus current I_bus, the second primary side internal phase shift angle D pb , the second secondary side internal phase shift angle D sb , and the second initial external phase shift angle Dssb1 Then, based on the battery current I_Pack and the current reference value I_Pack_Ref, the second compensation phase shift angle D is obtained. ssb2 Using the second compensation phase shift angle D ssb2 to compensate the second initial external phase shift angle D ssb1 to obtain the second external phase shift angle D ssb Finally, based on the second primary internal phase shift angle D pb , the second secondary internal phase shift angle D sb and the second external phase shift angle D ssb a second drive signal is generated. Among them, the second primary internal phase shift angle D pb refers to the phase shift angle between the first switch tube S1 and the fourth switch tube S4 in the second bidirectional DC conversion circuit. The second secondary internal phase shift angle D sb refers to the phase shift angle between the fifth switch tube S5 and the eighth switch tube S8 in the second bidirectional DC conversion circuit. The second external phase shift angle D ssb refers to the phase shift angle between the first switch tube S1 and the fifth switch tube S5 in the second bidirectional DC conversion circuit.

[0089] In this example, the second control circuit controls the second bidirectional DC conversion circuit through a battery current loop and triple phase shift (TPS) control.

[0090] Please refer to Figure 7 , Figure 7 which shows the specific control block diagram of the second control circuit controlling the second bidirectional DC conversion circuit to operate in the discharging state in this example. As Figure 7 shown, the second control circuit includes a second subtractor 141b, a second PI controller 142b, a second phase shifter 143b, a second TPS controller 145b, a second adder 146b, and a second pulse width modulator 144b. When the second control circuit receives an equalization charging instruction and the bus voltage Vbus reaches a preset voltage, the second subtractor 141b subtracts the battery current I_Pack from the current reference value I_Pack_Ref to obtain a current deviation value. The second PI controller 142b performs deviation adjustment on the current deviation value to obtain a current compensation value. The second phase shifter 143b calculates the current compensation value to obtain the second compensation phase shift angle D ssb2 . The second TPS controller 145b calculates the second primary internal phase shift angle D pb , the second secondary internal phase shift angle D sb and the second initial external phase shift angle D ssb1 based on the bus voltage Vbus and the bus current I_bus. The second adder 146b adds the second initial external phase shift angle D ssb1 and the second compensation phase shift angle D ssb2 to obtain the second external phase shift angle D ssb。The second pulse width modulator 144b performs modulation according to the second primary side internal phase shift angle D pb , the second secondary side internal phase shift angle D sb and the second external phase shift angle D ssb to generate a second driving signal.

[0091] In this example, the second TPS controller 145b can calculate a set of optimal internal and external phase shift angle solutions that minimize the effective value of the resonant cavity current based on the bus voltage Vbus and the bus current I_bus of the equalizing bus (i.e., the second primary side internal phase shift angle D pb , the second secondary side internal phase shift angle D sb and the second external phase shift angle D ssb ). The battery current I_Pack loop compensates according to the error between the battery current I_Pack and the current reference value I_Pack_Ref to ensure the dynamic performance of the loop and ensure the establishment and maintenance of the battery current I_Pack. By minimizing the effective value of the resonant cavity current, the second TPS controller 145b can reduce the conduction loss and thus improve the efficiency.

[0092] It can be understood that in this example, the second TPS controller 145b implements triple phase shift control of the second bidirectional DC conversion circuit in the same way as the first TPS controller 145a, and will not be elaborated here.

[0093] In another specific example of this application, the second control circuit can also control the second bidirectional DC conversion circuit through a power control loop and triple phase shift control. At this time, the battery information includes the battery power P_Pack of the second battery pack and the power reference value P_Pack_Ref. Correspondingly, after receiving the equalizing charge command, when the bus voltage Vbus reaches the preset voltage, the second control circuit can obtain the bus voltage Vbus, the bus current I_bus and the battery power P_Pack of the second battery pack of the equalizing bus in real time. Furthermore, the second primary side internal phase shift angle D pb , the second secondary side internal phase shift angle D sb and the second initial external phase shift angle D ssb1 are obtained according to the bus voltage Vbus and the bus current I_bus. Then, the second compensation phase shift angle D ssb2 is obtained according to the battery power P_Pack and the power reference value P_Pack_Ref, and the second initial external phase shift angle D ssb2 is compensated with the second compensation phase shift angle D ssb1 to obtain the second external phase shift angle D ssb . Finally, according to the second primary side internal phase shift angle D pb , the second secondary side internal phase shift angle D sb and the second external phase shift angle D ssbGenerate a second drive signal. It can be understood that in this embodiment, the second control circuit can calculate the battery power P_Pack by obtaining the battery current I_Pack and battery voltage of the second battery pack.

[0094] Please refer to Figure 8 , Figure 8 which shows the specific control block diagram of the second control circuit controlling the second bidirectional DC conversion circuit to operate in the discharging state in this embodiment. As Figure 8 shown, the second control circuit includes a second subtractor 141b, a second PI controller 142b, a second phase shifter 143b, a second TPS controller 145b, a second adder 146b, and a second pulse width modulator 144b. When the second control circuit receives an equalizing charge command and the bus voltage Vbus reaches a preset voltage, the second subtractor 141b subtracts the power reference value P_Pack_Ref from the battery power P_Pack to obtain a power deviation value. The second PI controller 142b performs deviation adjustment on the power deviation value to obtain a power compensation value. The second phase shifter 143b calculates the power compensation value to obtain a second compensation phase shift angle D ssb2 . The second TPS controller 145b calculates a second primary side internal phase shift angle D pb , a second secondary side internal phase shift angle D sb , and a second initial external phase shift angle D ssb1 based on the bus voltage Vbus and the bus current I_bus. The second adder 146b adds the second initial external phase shift angle D ssb1 and the second compensation phase shift angle D ssb2 to obtain a second external phase shift angle D ssb . The second pulse width modulator 144b modulates based on the second primary side internal phase shift angle D pb , the second secondary side internal phase shift angle D sb , and the second external phase shift angle D ssb to generate a second drive signal.

[0095] In this embodiment, the control object of the second control circuit is the battery power P_Pack of the second battery pack, which can achieve stable operation of charging the second battery pack. The effect is similar to that of the Figure 7 embodiment, and will not be elaborated here.

[0096] In the embodiments of the present application, when the power difference between any two battery packs 110 is greater than a preset difference, the controller 140 can control the first battery pack with the highest power to form a series system with the second battery pack with the lowest power, so that the first battery pack charges the second battery pack, solving the problem of imbalance between the battery packs 110, which is beneficial to improving the available capacity and service life of the multi-battery pack system 100.

[0097] When the first bidirectional DC converter corresponding to the first battery pack receives the equalizing discharge command, it takes the bus voltage of the equalizing bus as the control object and adopts the bus voltage loop and phase-shift control to establish and maintain the voltage of the equalizing bus. After the second bidirectional DC converter corresponding to the second battery pack receives the equalizing charge command and confirms that the bus voltage reaches the preset voltage, it then takes the current or power of the second battery pack as the control object and adopts the battery current loop and phase-shift control or the battery power loop and phase-shift control to stably provide the voltage on the equalizing bus to the second battery pack to achieve the impulse of the second battery pack. Among them, through phase-shift control, the first bidirectional DC converter and the second bidirectional DC converter can effectively reduce the conduction loss of the switching tubes, and the system efficiency can be improved without changing the hardware circuit.

[0098] Please refer to Figure 9 , Figure 9 FIG. is a schematic flowchart of an equalizing method provided by an embodiment of the present application. Among them, the equalizing method is applicable to the multi-battery pack system 100 of any of the above embodiments. In at least one implementation manner, the equalizing method is executed by the controller 140 in any of the above embodiments.

[0099] As Figure 9 shown, the equalizing method specifically includes the following steps:

[0100] Step S11: Obtain the power information of each battery pack.

[0101] Step S12: When it is determined according to the power information that the power difference between any two battery packs is greater than the first preset difference, determine the first battery pack with the highest power and the second battery pack with the lowest power.

[0102] Step S13: Control the first switch unit corresponding to the first battery pack to conduct, and send an equalizing discharge command to the first bidirectional DC converter corresponding to the first battery pack, so that the first bidirectional DC converter operates in the discharge state according to the equalizing discharge command.

[0103] Step S14: Control the second switch unit corresponding to the second battery pack to conduct, and send an equalizing charge command to the second bidirectional DC converter corresponding to the second battery pack, so that the second bidirectional DC converter operates in the charge state according to the equalizing charge command.

[0104] Step S15: When the power difference between the first battery pack and the second battery pack is less than or equal to the second preset difference, control the first switch unit and the second switch unit to disconnect, and control the first bidirectional DC converter and the second bidirectional DC converter to stop working.

[0105] Please refer to Figure 10 , Figure 10Schematic diagram of a control method provided by an embodiment of the present application. The control method is applicable to the multi-battery-pack system 100 of any of the above embodiments. In at least one implementation, the control method is executed by the control circuit 122 in the bidirectional DC converter 120 of any of the above embodiments.

[0106] Step S100: When receiving an equalization discharge command, obtain the bus information of the equalization bus in real time.

[0107] Among them, the bus information includes the bus voltage Vbus of the equalization bus.

[0108] Step S200: Generate a first drive signal according to the bus information.

[0109] Among them, the first drive signal is used to drive the bidirectional DC converter 120 to operate in the discharge state.

[0110] Step S300: When receiving an equalization charge command, obtain the bus information in real time.

[0111] Step S400: When the bus voltage reaches the preset voltage, obtain the battery information of the corresponding battery pack in real time.

[0112] Among them, the corresponding battery pack 110 refers to the battery pack 110 connected to the bidirectional DC converter 120 of the control circuit 122 that receives the equalization charge command, that is, the aforementioned second battery pack.

[0113] Step S500: Generate a second drive signal according to the bus information and the battery information, or generate a second drive signal according to the battery information.

[0114] Among them, the second drive signal is used to drive the bidirectional DC converter 120 to operate in the charge state.

[0115] It can be understood that in the embodiments of the present application, the same control circuit 122 will not execute steps S100 - S200 and steps S300 - S400 simultaneously. When the control circuit 122 receives an equalization discharge command, the control circuit 122 corresponds to the aforementioned first control circuit 122, corresponding to the first bidirectional DC conversion circuit 121 and the first battery pack. When the control circuit 122 receives an equalization charge command, the control circuit 122 corresponds to the aforementioned second control circuit 122, corresponding to the second bidirectional DC conversion circuit 121 and the second battery pack.

[0116] As Figure 11 shown, in some embodiments, step S200 may include:

[0117] Step 210: Obtain a first target phase shift angle according to the bus information.

[0118] In some specific examples, the first target phase shift angle includes a first external phase shift angle. Based on this, the control circuit can obtain the first external phase shift angle according to the difference between the bus voltage and the bus reference voltage.

[0119] In some other specific examples, the first target phase shift angle includes a first primary-side internal phase shift angle, a first secondary-side internal phase shift angle, and a first external phase shift angle. Correspondingly, as Figure 12 shown, step S210 may include:

[0120] Step 211: Obtain the first primary-side internal phase shift angle, the first secondary-side internal phase shift angle, and the first initial external phase shift angle according to the bus voltage and the bus current.

[0121] Step 212: Obtain the first compensation phase shift angle according to the bus voltage and the bus reference voltage.

[0122] Step 213: Compensate the first initial external phase shift angle with the first compensation phase shift angle to obtain the first external phase shift angle.

[0123] Step 220: Generate a first drive signal according to the first target phase shift angle.

[0124] Among them, when the first target phase shift angle only includes the first external phase shift angle, the control circuit 122 generates the first drive signal according to the first external phase shift angle.

[0125] When the first target phase shift angle includes the first primary-side internal phase shift angle, the first secondary-side internal phase shift angle, and the first external phase shift angle, the control circuit generates the first drive signal according to the first primary-side internal phase shift angle, the first secondary-side internal phase shift angle, and the first external phase shift angle.

[0126] As Figure 13 shown, in some embodiments, step S211 may include:

[0127] Step S211a: Calculate the normalized bus-side power according to the bus voltage and the bus current, and calculate the resonant cavity gain according to the bus voltage.

[0128] The control circuit 122 can calculate the normalized bus-side power according to the fundamental wave analysis method, and calculate the resonant cavity gain according to the turns ratio of the transformer T and the input voltage provided by the battery pack 110 to the bidirectional DC conversion circuit.

[0129] Step S211b: Determine whether the resonant cavity gain is less than or equal to 1.

[0130] Step S211c: When the resonant cavity gain is less than or equal to 1, determine whether the absolute value of the normalized bus-side power is less than or equal to the first bus power boundary value.

[0131] Step S211d: When the absolute value of the normalized bus-side power is less than or equal to the first bus power boundary value, calculate the first primary internal phase shift angle and the first initial external phase shift angle according to the normalized bus-side power and the resonator gain.

[0132] Among them, the first secondary internal phase shift angle is 0.

[0133] Step S211e: When the absolute value of the normalized bus-side power is greater than the first bus power boundary value, calculate the first initial external phase shift angle according to the normalized bus-side power.

[0134] Among them, the first primary internal phase shift angle and the first secondary internal phase shift angle are 0.

[0135] Step S211f: When the resonator gain is greater than 1, determine whether the absolute value of the normalized bus-side power is less than or equal to the second bus power boundary value.

[0136] Step S211h: When the absolute value of the normalized bus-side power is less than or equal to the second bus power boundary value, calculate the first secondary internal phase shift angle and the first initial external phase shift angle according to the normalized bus-side power and the resonator gain.

[0137] Among them, the first primary internal phase shift angle is 0.

[0138] Step S211i: When the absolute value of the normalized bus-side power is greater than the second bus power boundary value, calculate the first initial external phase shift angle according to the normalized bus-side power.

[0139] Among them, the first primary internal phase shift angle and the first secondary internal phase shift angle are 0.

[0140] In this embodiment, the calculation methods of the first primary internal phase shift angle, the first secondary internal phase shift angle, and the first external phase shift angle can refer to the description of the first TPS controller above, and will not be repeated here.

[0141] As Figure 14 shown, in some embodiments, step S500 includes:

[0142] Step S510: Obtain the second target phase shift angle according to the bus information and the battery information, or obtain the second target phase shift angle according to the battery information.

[0143] In some embodiments, the battery information includes the battery current and the current reference value corresponding to the battery pack 110, and the second target phase shift angle includes the second external phase shift angle. Correspondingly, the control circuit can obtain the second external phase shift angle according to the battery current and the current reference value, and then generate a second drive signal according to the second external phase shift angle.

[0144] In some embodiments, the bus information further includes the bus current of the equalizing bus, the battery information includes the battery current and the current reference value of the corresponding battery pack, and the second target phase shift angle includes a second primary inner phase shift angle, a second secondary inner phase shift angle, and a second outer phase shift angle. Correspondingly, as Figure 15 shown, step S510 may include:

[0145] Step S511: Obtain the second primary inner phase shift angle, the second secondary inner phase shift angle, and the second initial outer phase shift angle according to the bus voltage and the bus current.

[0146] Step S512: Obtain the second compensation phase shift angle according to the battery current and the current reference value.

[0147] Step S513: Compensate the second initial outer phase shift angle with the second compensation phase shift angle to obtain the second outer phase shift angle.

[0148] Among them, the specific implementation of step S511 may refer to Figure 13 steps S211a - S211i shown, that is, the calculation methods of the second primary inner phase shift angle, the second secondary inner phase shift angle, and the second initial outer phase shift angle are the same as those of the first primary inner phase shift angle, the first secondary inner phase shift angle, and the first outer phase shift angle, and this embodiment will not elaborate further on this.

[0149] In some other embodiments, the bus information further includes the bus current of the equalizing bus, the battery information includes the battery power and the power reference value of the corresponding battery pack, and the second target phase shift angle includes a second primary inner phase shift angle, a second secondary inner phase shift angle, and a second outer phase shift angle. Correspondingly, as Figure 16 shown, step S510 may include:

[0150] Step S515: Obtain the second primary inner phase shift angle, the second secondary inner phase shift angle, and the second initial outer phase shift angle according to the bus voltage and the bus current.

[0151] Step S516: Obtain the second compensation phase shift angle according to the battery power and the power reference value.

[0152] Step S517: Compensate the second initial outer phase shift angle with the second compensation phase shift angle to obtain the second outer phase shift angle.

[0153] Step S520: Generate a second drive signal according to the second target phase shift angle.

[0154] Among them, when the second target phase shift angle only includes the second outer phase shift angle, the control circuit generates a second drive signal according to the second outer phase shift angle.

[0155] When the second target phase-shifting angle includes a second primary-side internal phase-shifting angle, a second secondary-side internal phase-shifting angle, and a second external phase-shifting angle, the control circuit 122 can generate a second driving signal according to the second primary-side internal phase-shifting angle, the second secondary-side internal phase-shifting angle, and the second external phase-shifting angle.

[0156] It can be understood that the specific implementation content and beneficial effects of the above-mentioned equalization method and control method can refer to the corresponding content of the multi-battery-pack system 100 in any of the foregoing embodiments, and will not be elaborated herein.

[0157] The embodiment of the present application further provides a computer storage medium, which stores a computer program. When the computer program is executed by a processor, the processor is caused to execute the above-mentioned equalization method or control method.

[0158] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions according to the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer storage medium or transmitted through a computer storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired manner (such as coaxial cable, optical fiber, Digital Subscriber Line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a Digital Versatile Disc (DVD)), or a semiconductor medium (for example, a solid-state disk (SSD)), etc.

[0159] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. The foregoing storage media include: ROM, RAM, magnetic disks, or optical disks and other media that can store program codes. Without conflict, the technical features in this embodiment and the implementation solutions can be combined arbitrarily.

[0160] The above embodiments are only described in terms of the preferred embodiments of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present application shall fall within the protection scope determined by the claims of the present application.

Claims

1. A multi-battery pack system, characterized in that, Comprising at least two battery packs, at least two bidirectional DC converters, at least two switch units and a controller; Each of the battery packs is connected to one of the bidirectional DC converters through one of the switch units, and the bidirectional DC converter is connected to the equalization bus; the controller is connected to the battery packs, the bidirectional DC converters and the switch units; The controller is configured to: Obtain the power information of each of the battery packs; When it is determined according to the power information that the power difference between any of the battery packs is greater than a first preset difference, determine a first battery pack with the highest power and a second battery pack with the lowest power; Control the first switch unit corresponding to the first battery pack to conduct, and send an equalization discharge instruction to the first bidirectional DC converter corresponding to the first battery pack, so that the first bidirectional DC converter operates in a discharge state according to the equalization discharge instruction; Control the second switch unit corresponding to the second battery pack to conduct, and send an equalization charge instruction to the second bidirectional DC converter corresponding to the second battery pack, so that the second bidirectional DC converter operates in a charge state according to the equalization charge instruction; When the power difference between the first battery pack and the second battery pack is less than or equal to a second preset difference, control the first switch unit and the second switch unit to disconnect, and control the first bidirectional DC converter and the second bidirectional DC converter to stop working.

2. The multi-battery-pack system according to claim 1, wherein The first bidirectional DC converter includes a first bidirectional DC conversion circuit and a first control circuit, and the second bidirectional DC converter includes a second bidirectional DC conversion circuit and a second control circuit; The first battery pack is connected to the first end of the first bidirectional DC conversion circuit through the first switch unit, and the second end of the first bidirectional DC conversion circuit is connected to the equalization bus; the second battery pack is connected to the first end of the second bidirectional DC conversion circuit through the second switch unit, and the second end of the second bidirectional DC conversion circuit is connected to the equalization bus; The first control circuit and the second control circuit are connected to the controller. The first control circuit is configured to receive the equalization discharge instruction and control the first bidirectional DC conversion circuit to operate in a discharge state according to the equalization discharge instruction; the second control circuit is configured to receive the equalization charge instruction and control the second bidirectional DC conversion circuit to operate in a charge state according to the equalization charge instruction.

3. The multi-battery-pack system according to claim 2, wherein When receiving the equalization discharge instruction, the first control circuit is configured to: Obtain the bus information of the equalization bus in real time; Generate a first driving signal according to the bus information; wherein, the first driving signal is used to drive the first bidirectional DC conversion circuit to operate in a discharge state.

4. The multi-battery-pack system according to claim 3, wherein, The first bidirectional DC conversion circuit is a resonant DAB conversion circuit; the first control circuit is configured to: Obtain a first target phase shift angle according to the bus information; Generate the first driving signal according to the first target phase shift angle.

5. The multi-battery-pack system according to claim 4, wherein, The bus information includes the bus voltage and the bus reference voltage of the equalization bus. Correspondingly, the first target phase shift angle includes a first external phase shift angle; or The bus information includes the bus voltage, bus current, and bus reference voltage of the equalizing bus. Correspondingly, the first target phase shift angle includes a first primary internal phase shift angle, a first secondary internal phase shift angle, and a first external phase shift angle.

6. The multi-battery-pack system according to any one of claims 3 to 5, characterized in that After receiving the equalizing charge command, the second control circuit is configured to: Obtain the bus information of the equalizing bus in real time, where the bus information includes the bus voltage of the equalizing bus; When the bus voltage reaches a preset voltage, obtain the battery information of the second battery pack in real time; Generate a second drive signal based on the bus information and the battery information, or generate a second drive signal based on the battery information; wherein, the second drive signal is used to drive the second bidirectional DC conversion circuit to operate in a charging state.

7. The multi-battery-pack system according to claim 6, wherein The second control circuit is configured to: Obtain a second target phase shift angle based on the bus information and the battery information, or obtain a second target phase shift angle based on the battery information; Generate the second drive signal according to the second target phase shift angle.

8. The multi-battery-pack system according to claim 7, wherein The battery information includes the battery current and current reference value of the second battery pack, or the battery information includes the battery power and power reference value of the second battery pack; The bus information further includes the bus current of the equalizing bus; The second target phase shift angle includes a second primary internal phase shift angle, a second secondary internal phase shift angle, and a second external phase shift angle.

9. An equalization method for a multi-battery-pack system, characterized in that, The multi-battery pack system includes at least two battery packs, at least two bidirectional DC converters, and at least two switch units; Each of the battery packs is connected to one of the bidirectional DC converters through one of the switch units, and the bidirectional DC converter is connected to the equalizing bus; The equalizing method includes: Obtain the power information of each battery pack; When it is determined according to the power information that the power difference between any two battery packs is greater than a first preset difference, determine the first battery pack with the highest power and the second battery pack with the lowest power; Control the first switch unit corresponding to the first battery pack to turn on, and send an equalizing discharge command to the first bidirectional DC converter corresponding to the first battery pack, so that the first bidirectional DC converter operates in a discharging state according to the equalizing discharge command; Control the second switch unit corresponding to the second battery pack to turn on, and send an equalizing charge command to the second bidirectional DC converter corresponding to the second battery pack, so that the second bidirectional DC converter operates in a charging state according to the equalizing charge command; When the power difference between the first battery pack and the second battery pack is less than or equal to a second preset difference, control the first switch unit and the second switch unit to turn off, and control the first bidirectional DC converter and the second bidirectional DC converter to stop working.

10. A control method for a bidirectional DC converter, characterized in that, The bidirectional DC converter is applied to a multi-battery pack system, and one end of the bidirectional DC converter is connected to one of the battery packs through one of the switch units in the multi-battery pack system, and the other end of the bidirectional DC converter is connected to the equalizing bus in the multi-battery pack system; the control method includes: When receiving an equalizing discharge command, obtain the bus information of the equalizing bus in real time; wherein, the bus information includes the bus voltage of the equalizing bus. Generate a first driving signal according to the bus information; wherein, the first driving signal is used to drive the bidirectional DC converter to operate in a discharge state. When receiving an equalizing charge command, obtain the bus information in real time. When the bus voltage reaches a preset voltage, obtain the battery information corresponding to the battery pack in real time. Generate a second driving signal according to the bus information and the battery information, or generate a second driving signal according to the battery information; wherein, the second driving signal is used to drive the bidirectional DC converter to operate in a charging state.

11. The control method according to claim 10, characterized in that, The generating the first driving signal according to the bus information includes: Obtain a first target phase shift angle according to the bus information. Generate the first driving signal according to the first target phase shift angle.

12. The control method according to claim 11, characterized in that, The bus information further includes the bus reference voltage of the equalizing bus, and the first target phase shift angle includes a first external phase shift angle; the obtaining the first target phase shift angle according to the bus information includes: Obtain a first external phase shift angle according to the difference between the bus voltage and the bus reference voltage. Correspondingly, the generating the first driving signal according to the first target phase shift angle includes: Generate the first driving signal according to the first external phase shift angle.

13. The control method according to claim 11, characterized in that, The bus information further includes the bus current and the bus reference voltage of the equalizing bus, and the first target phase shift angle includes a first primary side internal phase shift angle, a first secondary side internal phase shift angle, and a first external phase shift angle; the obtaining the first target phase shift angle according to the bus information includes: Obtain the first primary side internal phase shift angle, the first secondary side internal phase shift angle, and a first initial external phase shift angle according to the bus voltage and the bus current. Obtain a first compensation phase shift angle according to the bus voltage and the bus reference voltage. Compensate the first initial external phase shift angle with the first compensation phase shift angle to obtain a first external phase shift angle. Correspondingly, the generating the first driving signal according to the first target phase shift angle includes: Generate the first driving signal according to the first primary side internal phase shift angle, the first secondary side internal phase shift angle, and the first external phase shift angle.

14. The control method according to claim 13, wherein The obtaining the first primary side internal phase shift angle, the first secondary side internal phase shift angle, and the first initial external phase shift angle according to the bus voltage and the bus current includes: Calculate the normalized bus side power according to the bus voltage and the bus current, and calculate the resonant cavity gain according to the bus voltage. When the resonant cavity gain is less than or equal to 1 and the absolute value of the normalized bus side power is less than or equal to a first bus power boundary value, calculate the first primary side internal phase shift angle and the first initial external phase shift angle according to the normalized bus side power and the resonant cavity gain; wherein, the first secondary side internal phase shift angle is 0. When the resonator gain is less than or equal to 1 and the absolute value of the normalized bus-side power is greater than the first bus power boundary value, calculate the first initial external phase shift angle according to the normalized bus-side power; wherein, the first primary-side internal phase shift angle and the first secondary-side internal phase shift angle are 0; When the resonator gain is greater than 1 and the absolute value of the normalized bus-side power is less than or equal to the second bus power boundary value, calculate the first secondary-side internal phase shift angle and the first initial external phase shift angle according to the normalized bus-side power and the resonator gain; wherein, the first primary-side internal phase shift angle is 0; When the resonator gain is greater than 1 and the absolute value of the normalized bus-side power is greater than the second bus power boundary value, calculate the first initial external phase shift angle according to the normalized bus-side power; wherein, the first primary-side internal phase shift angle and the first secondary-side internal phase shift angle are 0.

15. The control method according to claim 10, characterized in that, Generating the second drive signal according to the bus information and the battery information, or generating the second drive signal according to the battery information includes: Obtaining a second target phase shift angle according to the bus information and the battery information, or obtaining a second target phase shift angle according to the battery information; Generating the second drive signal according to the second target phase shift angle.

16. The control method according to claim 15, wherein, The battery information includes the battery current and the current reference value of the corresponding battery pack, and the second target phase shift angle includes a second external phase shift angle; obtaining the second target phase shift angle according to the battery information includes: Obtaining the second external phase shift angle according to the battery current and the current reference value; Correspondingly, generating the second drive signal according to the second target phase shift angle includes: Generating the second drive signal according to the second external phase shift angle.

17. The control method according to claim 15, wherein The bus information further includes the bus current of the equalizing bus, the battery information includes the battery current and the current reference value of the corresponding battery pack, and the second target phase shift angle includes a second primary-side internal phase shift angle, a second secondary-side internal phase shift angle, and a second external phase shift angle; obtaining the second target phase shift angle according to the bus information and the battery information includes: Obtaining the second primary-side internal phase shift angle, the second secondary-side internal phase shift angle, and the second initial external phase shift angle according to the bus voltage and the bus current; Obtaining a second compensation phase shift angle according to the battery current and the current reference value; Compensating the second initial external phase shift angle with the second compensation phase shift angle to obtain the second external phase shift angle; Correspondingly, generating the second drive signal according to the second target phase shift angle includes: Generating the second drive signal according to the second primary-side internal phase shift angle, the second secondary-side internal phase shift angle, and the second external phase shift angle.

18. The control method according to claim 15, wherein The bus information further includes the bus current of the equalizing bus, the battery information includes the battery power and the power reference value of the corresponding battery pack, and the second target phase shift angle includes a second primary-side internal phase shift angle, a second secondary-side internal phase shift angle, and a second external phase shift angle; obtaining the second target phase shift angle according to the bus information and the battery information includes: Obtaining the second primary-side internal phase shift angle, the second secondary-side internal phase shift angle, and the second initial external phase shift angle according to the bus voltage and the bus current; Obtain a second compensation phase shift angle according to the battery power and the power reference value; Compensate the second initial external phase shift angle with the second compensation phase shift angle to obtain a second external phase shift angle; Correspondingly, the generating the second drive signal according to the second target phase shift angle includes: Generate the second drive signal according to the second primary internal phase shift angle, the second secondary internal phase shift angle, and the second external phase shift angle.

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