Battery self-heating system, power drive system, control method, and vehicle

Abstract

The application relates to a battery self-heating system, which comprises a third switching circuit, a first power supply circuit, a second power supply circuit and a bidirectional direct-current conversion circuit, wherein the third switching circuit is electrically connected between the first power supply circuit and the second power supply circuit, the bidirectional direct-current conversion circuit is electrically connected with the first power supply circuit and the second power supply circuit, the battery self-heating system completes a heating cycle through charging and discharging of the first power supply circuit and the second power supply circuit once, that is, charging and discharging of the whole vehicle power battery twice, so that the heating efficiency of the battery self-heating system is improved. The application also relates to a control method of the battery self-heating system, a power driving system, a control method of the power driving system and a vehicle.

Description

Technical Field

[0001] This application relates to the field of electric vehicles, and more particularly to a battery self-heating system and its control method, a power drive system and its control method, and a vehicle. Background Technology

[0002] With the development of science and technology, new energy vehicles are gradually being widely used. As the core power source in new energy vehicles, power battery packs are often applied in various environments. However, the charging and discharging performance of power battery packs is easily affected by ambient temperature, especially at low temperatures where their charging capacity drops significantly. For example, when a power battery pack is in a low-temperature environment, its performance will be significantly reduced compared to normal temperatures. Furthermore, charging at low temperatures may cause permanent damage to the power battery pack, affecting its lifespan. To address the current shortcomings of power battery packs in terms of charging and discharging performance being easily affected by low temperatures, the industry typically employs external heating and self-heating methods. Common external heating methods include air heating, liquid heating, and electric heating wire heating.

[0003] However, commonly used external heating methods for power battery packs often suffer from low heating efficiency leading to energy waste, complex battery pack structures, and uneven heating causing localized rapid temperature increases. Currently, self-heating of the power battery is typically achieved by utilizing the different charge-discharge performance of two different types of power batteries at low temperatures. However, this method requires two different types of power batteries, increasing the complexity of the control system. Alternatively, self-heating of the power battery pack can be achieved by controlling the primary-to-secondary switching circuit of the on-board charger and using capacitors to cycle the charge and discharge of the battery. However, this self-heating method suffers from low heating efficiency, slow heating rate, and inability to control the heating time. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide a battery self-heating system and its control method, a power drive system and its control method, and a vehicle, which aims to solve the problems of low heating efficiency, slow heating rate, high complexity of battery management and control system, and inability to control heating as needed caused by the need to heat the power battery during the charging and discharging process in low temperature environment.

[0005] A battery self-heating system includes: a third switching circuit, a first power supply circuit, a second power supply circuit, and a bidirectional DC-DC converter circuit, wherein the third switching circuit is electrically connected between the first power supply circuit and the second power supply circuit, and the bidirectional DC-DC converter circuit is electrically connected to both the first power supply circuit and the second power supply circuit.

[0006] Optionally, the first power supply circuit and the second power supply circuit constitute a complete battery pack.

[0007] Optionally, the battery self-heating system further includes a first energy storage circuit and a second energy storage circuit, wherein the first energy storage circuit is electrically connected to the first power supply circuit and the bidirectional DC-DC converter circuit, and the second energy storage circuit is electrically connected to the second power supply circuit and the bidirectional DC-DC converter circuit.

[0008] Optionally, the bidirectional DC-DC converter circuit includes a bridge arm converter and a reactor. The bridge arm converter includes an N-phase bridge arm, the first ends of which are connected together to form a first bus terminal of the bridge arm converter, and the second ends of which are connected together to form a second bus terminal of the bridge arm converter. The first bus terminal of the bridge arm converter is electrically connected to the positive terminal of the second power supply circuit, and the second bus terminal of the bridge arm converter is electrically connected to the negative terminal of the second power supply circuit. The reactor includes an N-phase coil, the first ends of which are electrically connected to the midpoint of the bridge arm converter, and the second ends of which are connected together and electrically connected to the first power supply circuit.

[0009] Optionally, the bridge arm converter includes two-phase bridge arms, each phase bridge arm including an upper bridge arm and a lower bridge arm. The two upper bridge arms each include a first power switching unit and a third power switching unit, and the two lower bridge arms each include a second power switching unit and a fourth power switching unit. The first end of the first power switching unit and the first end of the third power switching unit are connected together to form a first bus terminal of the bridge arm converter. The second end of the second power switching unit and the second end of the fourth power switching unit are connected together to form a second bus terminal of the bridge arm converter. The second end of the first power switching unit is electrically connected to the first end of the second power switching unit, and the second end of the third power switching unit is electrically connected to the first end of the fourth power switching unit. The reactor includes a first coil and a second coil. The first end of the first coil is electrically connected to the first midpoint of the bridge arm converter, and the first end of the second coil is electrically connected to the second midpoint of the bridge arm converter. The second end of the first coil and the second end of the second coil are connected together and electrically connected to the first end of the first energy storage circuit.

[0010] Optionally, the battery self-heating system further includes a first switching circuit, a second switching circuit, and a fourth switching circuit, wherein one end of the first switching circuit is electrically connected to the positive terminal of the second power supply circuit and the third switching circuit, and the other end of the first switching circuit is electrically connected to the bidirectional DC-DC converter circuit; one end of the second switching circuit is electrically connected to the negative terminal of the first power supply circuit and the third switching circuit, and the other end is electrically connected to the first energy storage circuit and the bidirectional DC-DC converter circuit; one end of the fourth switching circuit is electrically connected to the negative terminal of the second power supply circuit, and the other end is electrically connected to the first energy storage circuit and the bidirectional DC-DC converter circuit.

[0011] Based on the same inventive concept, this application also provides a control method for a battery self-heating system, applied to the above-mentioned battery self-heating system. The control method includes: controlling a third switching circuit to disconnect, so as to divide the vehicle's entire battery pack into a first power supply circuit and a second power supply circuit; and controlling the first power supply circuit and / or the second power supply circuit to charge and discharge in a self-heating state through a bidirectional DC-DC converter circuit.

[0012] Optionally, controlling the charging and discharging of the first power supply circuit and / or the second power supply circuit to be in a self-heating state via the bidirectional DC-DC converter circuit includes: controlling the first power supply circuit to discharge to store energy in the first coil and the second coil in the bidirectional DC-DC converter circuit; controlling the first power supply circuit, the first coil, and the second coil to discharge to charge the second power supply circuit, the first energy storage circuit, and the second energy storage circuit; controlling the second power supply circuit and the second energy storage circuit to discharge to charge the first power supply circuit, the first coil, the second coil, and the first energy storage circuit; and controlling the first coil and the second coil to discharge to charge the first power supply circuit.

[0013] In summary, the control method for the battery self-heating system provided in this application controls the third switch circuit to disconnect, thereby dividing the vehicle's battery pack into a first power supply circuit and a second power supply circuit. The first power supply circuit and / or the second power supply circuit are then controlled to charge and discharge in a self-heating state through a bidirectional DC-DC converter circuit, thereby controlling the battery self-heating system and improving its heating efficiency.

[0014] Based on the same inventive concept, this application also provides a power drive system, which includes: a drive circuit, a power generation circuit, and the above-mentioned battery self-heating system, wherein the drive circuit is electrically connected to the second energy storage circuit of the battery self-heating system and the bidirectional DC-DC converter circuit; the power generation circuit is electrically connected to the drive circuit.

[0015] Optionally, the battery self-heating system further includes a pre-charge switch circuit, which is electrically connected to the positive terminal of the first power supply circuit and the first energy storage circuit of the battery self-heating system, for pre-charging the first energy storage circuit and the second energy storage circuit.

[0016] Optionally, the driving circuit includes an M-phase bridge arm, with the first ends of the M-phase bridge arm connected together to form a third bus terminal, and the second ends of the M-phase bridge arm connected together to form a fourth bus terminal. The third bus terminal of the driving circuit is electrically connected to the first bus terminal of the bridge arm converter, and the fourth bus terminal of the driving circuit is electrically connected to the second bus terminal of the bridge arm converter.

[0017] Optionally, the power generation circuit includes a W-phase bridge arm, with the first end of the W-phase bridge arm connected to form a fifth bus terminal and the second end of the W-phase bridge arm connected to form a sixth bus terminal. The fifth bus terminal of the power generation circuit is electrically connected to the third bus terminal of the drive circuit, and the sixth bus terminal of the power generation circuit is electrically connected to the fourth bus terminal of the drive circuit, for realizing vehicle power generation.

[0018] In summary, in the power drive system provided by this application, under the control of the first switch circuit, the second switch circuit, the third switch circuit, and the fourth switch circuit, the first power supply circuit and / or the second power supply circuit are controlled by the bidirectional DC-DC converter circuit in conjunction with the drive circuit and the generator circuit to realize the power supply and drive of the whole vehicle, so that the whole vehicle can still work normally when the first power supply circuit or the second power supply circuit fails.

[0019] Based on the same inventive concept, this application also provides a control method for a power drive system, applied to the aforementioned power drive system. The control method includes: controlling a third switching circuit to open or close, so as to separate or combine the first power circuit and the second power circuit into a complete battery pack for the vehicle; under the control of the first switching circuit, the second switching circuit, and the fourth switching circuit, controlling the first power circuit and / or the second power circuit through a bidirectional DC-DC converter circuit in conjunction with a drive circuit and a generator circuit to realize vehicle power-on and vehicle drive.

[0020] Optionally, the step of controlling the first power supply circuit and / or the second power supply circuit to achieve vehicle power-on and vehicle drive under the control of the first switch circuit, the second switch circuit, and the fourth switch circuit, through the bidirectional DC-DC converter circuit in conjunction with the drive circuit and the generator circuit, includes: controlling the first switch circuit and the second switch circuit to be disconnected, and the third switch circuit and the fourth switch circuit to be closed and connected, so that the first power supply circuit, the third switch circuit, the second power supply circuit, the fourth switch circuit, the first energy storage circuit, the bidirectional DC-DC converter circuit, the second energy storage circuit, the drive circuit, and the generator circuit constitute the vehicle high-voltage circuit, thereby achieving vehicle power-on and vehicle drive.

[0021] Optionally, the step of controlling the first power supply circuit and / or the second power supply circuit to achieve vehicle power-on and vehicle drive under the control of the first switch circuit, the second switch circuit, and the fourth switch circuit, through the bidirectional DC-DC converter circuit in conjunction with the drive circuit and the generator circuit, includes: controlling the first switch circuit, the third switch circuit, and the fourth switch circuit to be disconnected, and the second switch circuit to be closed and turned on, so that the first power supply circuit, the first energy storage circuit, the bidirectional DC-DC converter circuit, the second energy storage circuit, the drive circuit, the generator circuit, and the second switch circuit constitute the high-voltage circuit of the vehicle, thereby achieving vehicle power-on and vehicle drive.

[0022] Optionally, the step of controlling the first power supply circuit and / or the second power supply circuit to achieve vehicle power-on and vehicle drive under the control of the first switch circuit, the second switch circuit, and the fourth switch circuit, through the bidirectional DC-DC converter circuit in conjunction with the drive circuit and the generator circuit, includes: controlling the second switch circuit and the third switch circuit to be disconnected, and the first switch circuit and the fourth switch circuit to be closed and connected, so that the second power supply circuit, the first switch circuit, the bidirectional DC-DC converter circuit, the second energy storage circuit, the drive circuit, the generator circuit, the first energy storage circuit, and the fourth switch circuit constitute the high-voltage circuit of the vehicle, thereby achieving vehicle power-on and vehicle drive.

[0023] In summary, the control method for the power drive system provided in this application controls the third switch circuit to open or close, so as to separate or merge the first power circuit and the second power circuit into the vehicle's battery pack. Under the control of the first switch circuit, the second switch circuit, and the fourth switch circuit, the first power circuit and / or the second power circuit are controlled by the bidirectional DC-DC converter circuit in conjunction with the drive circuit and the generator circuit to realize the power supply and driving of the whole vehicle. This allows the power drive system to be controlled to realize the power supply and driving of the whole vehicle when the first power circuit or the second power circuit fails.

[0024] Based on the same inventive concept, this application also provides a vehicle that includes the above-described battery self-heating system or the above-described power drive system.

[0025] In summary, the battery self-heating system provided in this application completes one heating cycle by charging and discharging the vehicle's power battery once each through the first power circuit and the second power circuit, i.e., charging and discharging the power battery twice. This improves the heating efficiency of the battery self-heating system. Furthermore, the third switching circuit allows the vehicle battery to be divided into a first power circuit and a second power circuit as power batteries to provide power to the entire battery self-heating system. This eliminates the need for two different types of power batteries, and the heating effect of the first and second power circuits as power batteries with the same medium is similar. This reduces the complexity of the battery management and control system, eliminates the need for additional DC-DC voltage conversion devices, reduces the number of power devices used, saves circuit costs, reduces the complexity of the high-voltage system, and improves system reliability. Therefore, the battery self-heating system of this application solves the problems of high cost and poor safety caused by the need for power batteries to be charged and discharged in low-temperature environments in traditional technologies. Simultaneously, by controlling the charging and discharging current, the heating power can be adjusted in real time, thereby allowing for control of the heating time as needed. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the circuit structure of a power drive system disclosed in an embodiment of this application;

[0028] Figure 2 for Figure 1 The diagram shows the working topology of the battery self-heating system.

[0029] Figure 3 for Figure 2 The diagram shows a simplified circuit topology of the battery self-heating system.

[0030] Figure 4 for Figure 3 The diagram shows the current flow path of the first operating mode of the battery self-heating system.

[0031] Figure 5 for Figure 3 The diagram shows the current flow path in the second operating mode of the battery self-heating system.

[0032] Figure 6 for Figure 3 The diagram shows the current flow path for the third operating mode of the battery self-heating system.

[0033] Figure 7 for Figure 3 The diagram shows the current flow path for the fourth operating mode of the battery self-heating system.

[0034] Figure 8 This is a schematic flowchart of a control method for a battery self-heating system disclosed in an embodiment of this application;

[0035] Figure 9 for Figure 8 A flowchart illustrating step S20 in the control method shown;

[0036] Figure 10 for Figure 1 A schematic diagram of the current flow path in the first operating mode of the power drive system shown.

[0037] Figure 11 for Figure 1 A schematic diagram of the current flow path in the second operating mode of the power drive system shown.

[0038] Figure 12 for Figure 1 A schematic diagram of the current flow path in the third operating mode of the power drive system shown.

[0039] Figure 13 This is a flowchart illustrating a control method for a power drive system disclosed in an embodiment of this application;

[0040] Figure 14 for Figure 13 The flowchart of step S200 in the control method shown is illustrated. Detailed Implementation

[0041] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0042] The following descriptions of the embodiments are based on the accompanying illustrations and are used to illustrate specific embodiments in which this application can be implemented. The component designations used herein, such as "first," "second," etc., are merely for distinguishing the described objects and do not have any sequential or technical meaning. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages). Directional terms used in this application, such as "up," "down," "front," "rear," "left," "right," "inner," "outer," "side," etc., are merely for reference to the accompanying drawings. Therefore, the use of directional terms is for better and clearer explanation and understanding of this application, and does not indicate or imply that the referred device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this application.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order.

[0044] Furthermore, the terms "comprising," "may include," "include," or "may include" as used in this application indicate the presence of the corresponding functions, operations, elements, etc., disclosed, but do not limit one or more other functions, operations, elements, etc. Moreover, the terms "comprising" or "include" indicate the presence of the corresponding features, numbers, steps, operations, elements, components, or combinations thereof disclosed in the specification, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, and are intended to cover non-exclusive inclusion. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application.

[0045] As the core power source in new energy vehicles, power battery packs are often used in various environments. However, their charging and discharging performance is easily affected by ambient temperature, especially at low temperatures where their charging capacity drops significantly. For example, when a power battery pack is in a low-temperature environment, its performance will be significantly reduced compared to normal temperatures, and charging at low temperatures may cause permanent damage to the battery pack, affecting its lifespan. To address the current shortcomings of power battery packs in terms of charging and discharging performance being easily affected by low temperatures, the industry typically employs external heating and self-heating methods. Common external heating methods include air heating, liquid heating, and electric heating wire heating.

[0046] However, heating power batteries via air or liquid heating suffers from low heating efficiency, resulting in energy waste. Heating power batteries with heating wires requires additional heating equipment, increasing the overall vehicle cost, and also suffers from uneven heating, causing localized rapid temperature increases in the power battery, which can easily lead to safety accidents. Furthermore, self-heating of the power battery is often achieved by utilizing the different charging and discharging performance of two different types of power batteries at low temperatures, but this method requires two different types of power batteries, increasing the complexity of the control system. Controlling the power battery self-heating based on the primary / secondary switching circuit of the on-board charger and using capacitors to cycle the charge and discharge of the battery has shortcomings such as low heating efficiency, slow heating rate, and inability to control the heating time. Therefore, how to solve the problems of low heating efficiency, slow heating rate, and high complexity of battery management and control systems caused by the need to heat the power battery during charging and discharging in low-temperature environments in traditional technologies has become an urgent problem for engineers to solve.

[0047] This application aims to provide a self-heating solution for power batteries that solves the aforementioned technical problems. It addresses issues such as low heating efficiency, slow heating rate, high complexity of the battery management and control system, and inability to control heating as needed during the charging and discharging process of power batteries in low-temperature environments. Details will be elaborated in subsequent embodiments. This application provides a detailed description of a battery self-heating system and its control method, a power drive system and its control method, and a vehicle.

[0048] Please see Figure 1 This is a schematic diagram of the circuit structure of a power drive system disclosed in an embodiment of this application. Figure 1As shown, this application provides a power drive system 10, which may include at least a battery self-heating system 100, a drive circuit 160, and a power generation circuit 180. The drive circuit 160 is electrically connected to the battery self-heating system 100, and the power generation circuit 180 is electrically connected to the drive circuit 160.

[0049] In this embodiment of the application, the battery self-heating system 100 includes a first switching circuit 101, a second switching circuit 102, a third switching circuit 104, a fourth switching circuit 106, a first energy storage circuit 107, a second energy storage circuit 108, a first power supply circuit 111, a second power supply circuit 112, a pre-charge switching circuit 120, and a bidirectional direct current (DC) converter circuit 130.

[0050] In this embodiment, the first switching circuit 101 includes a first switching unit K1, the second switching circuit 102 includes a second switching unit K4, the third switching circuit 104 includes a third switching unit K5, and the fourth switching circuit 106 includes a fourth switching unit K6. The first terminal of the first switching unit K1 is electrically connected to the positive terminal of the second power supply circuit 112 and the second terminal of the third switching unit K5, and the second terminal of the first switching unit K1 is electrically connected to the first bus terminal of the bidirectional DC converter circuit 130. The first terminal of the second switching unit K4 is electrically connected to the negative terminal of the first power supply circuit 111 and the first terminal of the third switching unit K5, and the second terminal of the second switching unit K4 is electrically connected to the second terminal of the first storage capacitor C1, the bidirectional DC converter circuit 130, and the second terminal of the fourth switching unit K6. The first terminal of the third switching unit K5... One end of the third switch unit K5 is electrically connected to the negative terminal of the first power supply circuit 111 and the first end of the second switch unit K4. The second end of the third switch unit K5 is electrically connected to the positive terminal of the second power supply circuit 112 and the first end of the first switch unit K1, that is, the third switch unit K5 is electrically connected between the first power supply circuit 111 and the second power supply circuit 112. The first end of the fourth switch unit K6 is electrically connected to the negative terminal of the second power supply circuit 112. The second end of the fourth switch unit K6 is electrically connected to the second end of the first storage capacitor C1 and the second bus terminal of the bidirectional DC conversion circuit 130.

[0051] In this embodiment, the first energy storage circuit 107 includes a first storage capacitor C1, and the second energy storage circuit 108 includes a second storage capacitor C2. The first terminal of the first storage capacitor C1 is electrically connected to the bidirectional DC-DC converter circuit 130 and to the first power supply circuit 111 via the pre-charge switch circuit 120. The second terminal of the first storage capacitor C1 is electrically connected to the second terminal of the second switch unit K4, the second terminal of the fourth switch unit K6, and the second bus terminal of the bidirectional DC-DC converter circuit 130. The first terminal of the second storage capacitor C2 is electrically connected to the first bus terminal of the bidirectional DC-DC converter circuit 130 and the third bus terminal of the drive circuit 160. The second terminal of the second storage capacitor C2 is electrically connected to the second bus terminal of the bidirectional DC-DC converter circuit 130 and the fourth bus terminal of the drive circuit 160, and is electrically connected to the second power supply circuit 112 via the second bus terminal of the bidirectional DC-DC converter circuit 130 and the fourth switch unit K6.

[0052] The positive terminal of the first power supply circuit 111 is electrically connected to the pre-charge switch circuit 120, and the negative terminal of the first power supply circuit 111 is electrically connected to the first terminal of the second switch unit K4 and the first terminal of the third switch unit K5. The first power supply circuit 111 is used to provide power to the entire battery self-heating system 100, realizing functions such as vehicle driving, power generation, charging, feedback, and voltage boosting.

[0053] The positive terminal of the second power supply circuit 112 is electrically connected to the second terminal of the third switching unit K5 and the first terminal of the first switching unit K1, and the negative terminal of the second power supply circuit 112 is electrically connected to the first terminal of the fourth switching unit K6. The second power supply circuit 112 is used to provide power to the entire battery self-heating system 100, realizing functions such as vehicle driving, power generation, charging, feedback, and voltage boosting.

[0054] In an exemplary embodiment, the first power circuit 111 and the second power circuit 112 may be batteries with the same dielectric material, constituting the vehicle's complete battery pack. It is understood that when the first power circuit 111 and the second power circuit 112 operate independently, the battery self-heating system 100 activates the sub-pack battery self-heating control mode; when the first power circuit 111 and the second power circuit 112 are connected in series and operate simultaneously, the battery self-heating system 100 does not activate the sub-pack battery self-heating control mode.

[0055] In an exemplary embodiment, the DC conversion circuit 130, the drive circuit 160, and the power generation circuit 180 constitute the power control section of the vehicle.

[0056] The precharge switching circuit 120 includes a fifth switching unit K8, a sixth switching unit K9, and a precharge resistor R. The first terminal of the fifth switching unit K8 is electrically connected to the positive terminal of the first power supply circuit 111 and the first terminal of the sixth switching unit K9. The second terminal of the fifth switching unit K8 is electrically connected to the second terminal of the precharge resistor R, the first terminal of the first storage capacitor C1, and the bidirectional DC conversion circuit 130.

[0057] The first end of the sixth switching unit K9 is electrically connected to the first end of the fifth switching unit K8 and the positive terminal of the first power supply circuit 111, and the second end of the sixth switching unit K9 is electrically connected to the first end of the pre-charge resistor R.

[0058] The first end of the pre-charge resistor R is electrically connected to the second end of the sixth switching unit K9, and the second end of the pre-charge resistor R is electrically connected to the second end of the fifth switching unit K8 and the first end of the first storage capacitor C1.

[0059] In this embodiment of the application, the precharge switch circuit 120 is used to precharge the first storage capacitor C1 and the second storage capacitor C2 to prevent the first storage capacitor C1 and the second storage capacitor C2 from being damaged by current surges when powered on.

[0060] The bidirectional DC-DC converter 130 is electrically connected to both the first power supply circuit 111 and the second power supply circuit 112. The bidirectional DC-DC converter 130 includes a bridge arm converter 131 and a reactor 133. The bridge arm converter 131 comprises N-phase bridge arms, with the first ends of the N-phase bridge arms forming a common first bus terminal, and the second ends of the N-phase bridge arms forming a common second bus terminal. The first bus terminal of the bridge arm converter 131 is electrically connected to the positive terminal of the second power supply circuit 112 via the first switching unit K1, and the second bus terminal of the bridge arm converter 131 is electrically connected to the negative terminal of the second power supply circuit 112 via the fourth switching unit K6.

[0061] In an exemplary embodiment, each phase bridge arm includes an upper bridge arm and a lower bridge arm, which are connected in series, and the midpoint of the bridge arm is formed between the upper and lower bridge arms. In this embodiment, the midpoints of the bridge arm converter 131 are points A and B. It is understood that, for ease of description, point A can be defined as the first midpoint A, and point B can be defined as the second midpoint B.

[0062] Each phase bridge arm includes a power switching unit in both its upper and lower arms. The power switching unit can be a transistor, an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or a combination thereof.

[0063] In this embodiment, for ease of description of the phase bridge arm connection method in the bridge arm converter 131, a two-phase bridge arm is used as an example. Specifically, the bridge arm converter 131 includes two phase bridge arms, each including an upper bridge arm and a lower bridge arm, specifically two upper bridge arms and two lower bridge arms. The two upper bridge arms each include a first power switch unit Q1 and a third power switch unit Q3, and the two lower bridge arms each include a second power switch unit Q2 and a fourth power switch unit Q4. The first terminal of the first power switch unit Q1 and the first terminal of the third power switch unit Q3 are connected together to form the first bus terminal of the bridge arm converter 131. The second terminal of the second power switch unit Q2 and the second terminal of the fourth power switch unit Q4 are connected together to form the second bus terminal of the bridge arm converter 131. The second terminal of the first power switch unit Q1 is electrically connected to the first terminal of the second power switch unit Q2, and the second terminal of the third power switch unit Q3 is electrically connected to the first terminal of the fourth power switch unit Q4.

[0064] The reactor 133 includes an N-phase coil. The first end of the N-phase coil is electrically connected to the midpoint of the N-phase bridge arm of the bridge arm converter 131. The second end of the N-phase coil is shared and electrically connected to the negative terminal of the second power supply circuit 112 through the pre-charge switch circuit 120. In this embodiment, for ease of description of the connection method of the N-phase coil in the reactor 133, a two-phase coil is used as an example. Specifically, the reactor 133 includes a first coil L1 and a second coil L2. The first end of the first coil L1 is electrically connected to the first midpoint A, and the first end of the second coil L2 is electrically connected to the second midpoint B. The second end of the first coil L1 and the second end of the second coil L2 are shared and electrically connected to the first end of the first storage capacitor C1 and the second end of the fifth switch unit K8.

[0065] In this embodiment of the application, under the control of the first switching circuit 101, the second switching circuit 102, the third switching circuit 104 and the fourth switching circuit 106, the bidirectional DC-DC converter circuit 130, in conjunction with the first energy storage circuit 107 and the second energy storage circuit 108, controls the charging and discharging of the first power supply circuit 111 and / or the second power supply circuit 112, so that the first power supply circuit 111 and / or the second power supply circuit 112 perform self-heating.

[0066] The driving circuit 160 includes M-phase bridge arms. The first ends of the M-phase bridge arms are connected to form the third bus terminal, and the second ends of the M-phase bridge arms are connected to form the fourth bus terminal. The third bus terminal of the driving circuit 160 is electrically connected to the first bus terminal of the bridge arm converter 131, and the fourth bus terminal of the driving circuit 160 is electrically connected to the second bus terminal of the bridge arm converter 131. In an exemplary embodiment, each phase bridge arm includes an upper bridge arm and a lower bridge arm, which are connected in series. Each phase bridge arm includes a power switching unit in both its upper and lower bridge arms. The power switching unit can be a transistor, an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or a combination thereof.

[0067] In this embodiment of the application, the drive circuit 160 is used to drive the entire vehicle.

[0068] The power generation circuit 180 includes W-phase bridge arms. The first ends of the W-phase bridge arms are connected together to form a fifth bus terminal, and the second ends of the W-phase bridge arms are connected together to form a sixth bus terminal. The fifth bus terminal of the power generation circuit 180 is electrically connected to the third bus terminal of the drive circuit 160, and the sixth bus terminal of the power generation circuit 180 is electrically connected to the fourth bus terminal of the drive circuit 160. In an exemplary embodiment, each phase bridge arm includes an upper bridge arm and a lower bridge arm, which are connected in series. Each phase bridge arm includes a power switching unit in both its upper and lower bridge arms. The power switching unit can be a transistor, an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or a combination thereof.

[0069] In this embodiment of the application, the power generation circuit 180 is used to generate electricity for the entire vehicle.

[0070] Therefore, in the power drive system provided in this application, the battery self-heating system completes one heating cycle by charging and discharging once each through the first power circuit 111 and the second power circuit 112, i.e., the vehicle power battery is charged and discharged twice. This improves the heating efficiency of the battery self-heating system. Simultaneously, due to the high power of the bidirectional DC-DC converter circuit 130 and its non-isolated topology design, the power devices have strong overcurrent capability, and the effective self-heating current of the battery can reach over 100A, thus increasing the heating rate of the battery self-heating system. Furthermore, the third switching circuit 104 can divide the vehicle battery into the first power circuit 111 and the second power circuit 112 as power batteries to provide power to the entire battery self-heating system 100. This eliminates the need for two different power batteries, and since the first power circuit 111 and the second power circuit 112, as power batteries with the same medium, have similar heating effects, the complexity of the battery management and control system is reduced. This eliminates the need for additional DC-DC voltage conversion devices, reduces the number of power devices used, saves circuit costs, reduces the complexity of the high-voltage system, and improves system reliability. Therefore, the battery self-heating system of this application solves the problems of high cost and poor safety caused by the need for power batteries to be heated during the charging and discharging process in low-temperature environments in traditional technologies. At the same time, by controlling the charging and discharging current, the heating power can be adjusted in real time, and the heating time can be controlled as needed.

[0071] Please see Figure 2 and Figure 3 , Figure 2 for Figure 1 The diagram shows the working topology of the battery self-heating system. Figure 3 for Figure 2 The diagram shows a simplified circuit topology of the battery self-heating system. Figure 2 and Figure 3 As shown, the first switch unit K1, the second switch unit K4, the fourth switch unit K6, and the fifth switch unit K8 are closed and conducting, while the third switch unit K5 and the sixth switch unit K9 are open, and both the drive circuit 160 and the power generation circuit 180 are in the off state. (Combined with...) Figure 2 and Figure 3 It is understood that the control methods of the bidirectional DC conversion circuit 130 of the battery self-heating system include, but are not limited to: single-phase conduction, two-phase conduction and two-phase interleaved conduction. This application embodiment uses two-phase conduction as an example to describe the battery self-heating control. It can be understood that single-phase conduction and two-phase interleaved conduction are both within the protection scope of this application.

[0072] Please see Figure 4 , Figure 4 for Figure 3The diagram shows the current flow path for the first operating mode of the battery self-heating system. Figure 4 As shown, the first power circuit 111 discharges, the second power switch unit Q2 and the fourth power switch unit Q4 are turned on, and the first power switch unit Q1 and the third power switch unit Q3 are turned off. The current flows out of the first power circuit 111, through the fifth switch unit K8 to the first coil L1 and the second coil L2. The current through the first coil L1 flows to the second power switch unit Q2, and the current through the second coil L2 flows to the fourth power switch unit Q4. The currents flowing through the second power switch unit Q2 and the fourth power switch unit Q4 are combined at the second bus terminal of the bridge arm converter 131, and finally flow back to the first power circuit 111 through the second switch unit K4. In this stage, the first coil L1 and the second coil L2 act as energy storage elements, storing energy. The first power circuit 111 discharges, storing energy in the first coil L1 and the second coil L2. That is, this stage is the inductor energy storage stage.

[0073] Please see Figure 5 , Figure 5 for Figure 3 The diagram shows the current flow path for the second operating mode of the battery self-heating system. Figure 5 As shown, the first power supply circuit 111 discharges, the second power supply circuit 112 charges, the second power switch unit Q2 and the fourth power switch unit Q4 are turned off, and the first power switch unit Q1 and the third power switch unit Q3 are turned on. The current flows out of the first power supply circuit 111, passes through the fifth switch unit K8 to the first coil L1 and the second coil L2, the current passing through the first coil L1 flows to the first power switch unit Q1, and the current passing through the second coil L2 flows to the third power switch unit Q3. The currents flowing through the first power switch unit Q1 and the third power switch unit Q3 are combined at the first bus terminal of the bridge arm converter 131, and then flow to the second storage capacitor C2 and the second power supply circuit 112 respectively. Finally, the current passing through the second storage capacitor C2 flows back to the first power supply circuit 111 through the second switch unit K4. During this stage, the first power supply circuit 111, the first coil L1, and the second coil L2 discharge, meaning that the first power supply circuit 111, the first coil L1, and the second coil L2 simultaneously charge the second storage capacitor C2 and the second power supply circuit 112. In other words, this stage is the boost stage.

[0074] Please see Figure 6 , Figure 6 for Figure 3The diagram shows the current flow path for the third operating mode of the battery self-heating system. Figure 6 As shown, the first power circuit 111 is charging, the second power circuit 112 is discharging, the second power switch unit Q2 and the fourth power switch unit Q4 are off, and the first power switch unit Q1 and the third power switch unit Q3 are on. The current flows from the positive terminal of the second power circuit 112, through the first switch unit K1 to the first power switch unit Q1 and the third power switch unit Q3 respectively. The current through the first power switch unit Q1 flows to the first coil L1, and the current through the third power switch unit Q3 flows to the second coil L2. The currents flowing through the first coil L1 and the second coil L2 are combined, then flow through the fifth switch unit K8 to the first power circuit 111, and finally flow through the second switch unit K4 and the fourth switch unit K6 back to the negative terminal of the second power circuit 112. During this stage, the second power circuit 112 and the second storage capacitor C2 discharge, charging the first power circuit 111, the first coil L1, the second coil L2, and the first storage capacitor C1. That is, this stage is the step-down stage.

[0075] Please see Figure 7 , Figure 7 for Figure 3 The diagram shows the current flow path for the fourth operating mode of the battery self-heating system. Figure 7 As shown, the first power supply circuit 111 is charging, the first coil L1 and the second coil L2 are discharging, the second power switch unit Q2 and the fourth power switch unit Q4 are conducting, and the first power switch unit Q1 and the third power switch unit Q3 are turning off. The current flows out from the first coil L1 and the second coil L2 respectively to complete the convergence, flows through the fifth switch unit K8 to the positive terminal of the first power supply circuit 111, and then through the negative terminal of the first power supply circuit 111 and the second switch unit K4 to the second power switch unit Q2 and the fourth power switch unit Q4 respectively. The current through the second power switch unit Q2 flows to the first coil L1, and the current through the fourth power switch unit Q4 flows to the second coil L2. During this stage, the first coil L1 and the second coil L2 discharge, and the induced electromotive force charges the first power supply circuit 111. That is, this stage is the inductor freewheeling stage.

[0076] Therefore, in the battery self-heating system provided in this application, the vehicle battery can be divided into a first power circuit 111 and a second power circuit 112 through the third switching unit K5. The first power circuit 111 is electrically connected to the first storage capacitor C1 through the second switching unit K4, and the second power circuit 112 is electrically connected to the second storage capacitor C2 through the first switching unit K1. This allows the first power circuit 111 and the second power circuit 112 to each charge and discharge once, meaning the vehicle power battery is charged and discharged twice, and the battery self-heating system completes one heating cycle, thus improving the heating efficiency of the battery self-heating system. Simultaneously, due to the high power of the bidirectional DC converter circuit 130 and its non-isolated topology design, the power devices have strong overcurrent capability, and the effective self-heating current of the battery can reach over 100A, thereby improving the heating rate of the battery self-heating system. Therefore, the battery self-heating system of this application solves the problems of high cost and poor safety caused by the need for power batteries to be heated during the charging and discharging process in low-temperature environments in traditional technologies. At the same time, by controlling the charging and discharging current, the heating power can be adjusted in real time, and the heating time can be controlled as needed.

[0077] Please see Figure 8 , Figure 8 This is a flowchart illustrating the control method for a battery self-heating system. Figure 8 As shown, the control method of the battery self-heating system includes at least the following steps.

[0078] S10, the third switch circuit 104 is disconnected to divide the vehicle's battery pack into the first power circuit 111 and the second power circuit 112.

[0079] S20, the first power supply circuit 111 and / or the second power supply circuit 112 are controlled to charge and discharge through the bidirectional DC-DC converter circuit 130 so as to be in a self-heating state.

[0080] Please see Figure 9 In this embodiment, step S20 includes at least the following steps.

[0081] S21. Control the first power supply circuit 111 to discharge, so as to store energy for the first coil L1 and the second coil L2 in the bidirectional DC-DC converter circuit 130.

[0082] S22. Control the first power supply circuit 111, the first coil L1 and the second coil L2 to discharge, so as to charge the second power supply circuit 112, the first energy storage circuit 107 and the second energy storage circuit 108.

[0083] S23, control the second power supply circuit 112 and the second energy storage circuit 108 to discharge, so as to charge the first power supply circuit 111, the first coil L1, the second coil L2 and the first energy storage circuit 107.

[0084] S24. Control the first coil L1 and the second coil L2 to discharge so as to charge the first power supply circuit 111.

[0085] Please see Figure 10 , Figure 10 for Figure 1 The diagram shows the current flow path for the first operating mode of the power drive system. Figure 10 As shown, the first switch unit K1 and the second switch unit K4 are both open, and the third switch unit K5 is closed and conducting. The first power circuit 111 and the second power circuit 112 are electrically connected through the third switch unit K5, and the first power circuit 111 and the second power circuit 112 are connected in series. At this time, the battery self-heating system 100 does not activate the battery self-heating control mode. When the fourth switch unit K6 is closed and conducting, the sixth switch unit K9 is first closed and conducting. Then, the first power circuit 111 pre-charges the first storage capacitor C1 through the sixth switch unit K9 and the pre-charging resistor R. When the voltage across the first storage capacitor C1 is consistent with the voltage of the first power circuit 111, the pre-charging is completed. At this time, the sixth switch unit K9 is opened, and the fifth switch unit K8 is closed and conducting, completing the high-voltage power supply of the entire vehicle. The first power supply circuit 111, the third switch unit K5, the second power supply circuit 112, the fourth switch unit K6, the first storage capacitor C1, the bidirectional DC conversion circuit 130, the second storage capacitor C2, the drive circuit 160, the power generation circuit 180, and the fifth switch unit K8 form a battery self-heating circuit, which simultaneously realizes the functions of vehicle driving, power generation, charging, feedback, and voltage boosting.

[0086] Please see Figure 11 , Figure 11 for Figure 1 The diagram shows the current flow path for the second operating mode of the power drive system. Figure 11As shown, when the second power supply circuit 112 malfunctions, in order to ensure the normal operation of the vehicle, the third switch unit K5 needs to be disconnected to break the electrical connection between the first power supply circuit 111 and the second power supply circuit 112. Then, both the first switch unit K1 and the fourth switch unit K6 are disconnected to break the electrical connection between the second power supply circuit 112 and the first storage capacitor C1, the second storage capacitor C2, the bidirectional DC converter circuit 130, the drive circuit 160, and the generator circuit 180. The first storage capacitor C1, the second storage capacitor C2, the bidirectional DC converter circuit 130, the drive circuit 160, and the generator circuit 180 constitute the high-voltage circuit of the vehicle. Simultaneously, the second switch unit K4 is closed and turned on, electrically connecting the negative terminal of the first power supply circuit 111 to the second terminal of the first storage capacitor C1, the second bus terminal of the bidirectional DC conversion circuit 130, the second terminal of the second storage capacitor C2, the fourth bus terminal of the drive circuit 160, and the sixth bus terminal of the generator circuit 180 through the second switch unit K4. That is, the negative terminal of the first power supply circuit 111 is electrically connected to the high-voltage circuit of the vehicle through the second switch unit K4. Then, the sixth switch unit K9 is closed and turned on, so the first power supply circuit 111 precharges the first storage capacitor C1 through the sixth switch unit K9 and the pre-charging resistor R. When the voltage across the first storage capacitor C1 is consistent with the voltage of the first power supply circuit 111, the pre-charging is completed. At this time, the sixth switch unit K9 is disconnected, and the fifth switch unit K8 is closed and turned on, completing the high-voltage power supply of the vehicle. The first power supply circuit 111, the fifth switching unit K8, the first storage capacitor C1, the bidirectional DC conversion circuit 130, the second storage capacitor C2, the drive circuit 160, the power generation circuit 180, and the second switching unit K4 form a battery self-heating circuit, which simultaneously realizes the functions of vehicle driving, power generation, charging, feedback, and voltage boosting.

[0087] Please see Figure 12 , Figure 12 for Figure 1 The diagram shows the current flow path for the third operating mode of the power drive system. Figure 12As shown, when the first power supply circuit 111 fails, in order to ensure the normal operation of the vehicle, the third switch unit K5 needs to be disconnected to break the electrical connection between the first power supply circuit 111 and the second power supply circuit 112. Then, the fifth switch unit K8, the sixth switch unit K9, and the second switch unit K4 are all disconnected to break the electrical connection between the first power supply circuit 111 and the first storage capacitor C1, the second storage capacitor C2, the bidirectional DC converter circuit 130, the drive circuit 160, and the generator circuit 180. The first storage capacitor C1, the second storage capacitor C2, the bidirectional DC converter circuit 130, the drive circuit 160, and the generator circuit 180 constitute the high-voltage circuit of the vehicle. Simultaneously, the fourth switch unit K6 is closed and turned on, electrically connecting the negative terminal of the second power supply circuit 112 to the second terminal of the first storage capacitor C1, the second bus terminal of the bidirectional DC converter circuit 130, the second terminal of the second storage capacitor C2, the fourth bus terminal of the drive circuit 160, and the sixth bus terminal of the generator circuit 180 through the fourth switch unit K6. Finally, the first switch unit K1 is closed and turned on, completing the high-voltage power supply to the vehicle. The second power supply circuit 112, the first switch unit K1, the bidirectional DC converter circuit 130, the second storage capacitor C2, the drive circuit 160, the generator circuit 180, the first storage capacitor C1, and the fourth switch unit K6 form a battery self-heating circuit, simultaneously realizing the functions of vehicle driving, power generation, charging, feedback, and voltage boosting.

[0088] Please see Figure 13 , Figure 13 This is a flowchart illustrating the control method for a power drive system. (Example:) Figure 13 As shown, the control method of the power drive system includes at least the following steps.

[0089] S100, control the third switch circuit 104 to open or close, so as to separate or combine the first power circuit 111 and the second power circuit 112 into the vehicle's battery pack.

[0090] S200, under the control of the first switch circuit 101, the second switch circuit 102 and the fourth switch circuit 106, the bidirectional DC-DC converter circuit 130, in conjunction with the drive circuit 160 and the generator circuit 180, controls the first power supply circuit 111 and / or the second power supply circuit 112 to realize the power supply and drive of the whole vehicle.

[0091] Please see Figure 14 In this embodiment, step S200 includes at least the following steps.

[0092] S210, the first switch circuit 101 and the second switch circuit 102 are both disconnected, and the third switch circuit 104 and the fourth switch circuit 106 are closed and connected, so that the first power supply circuit 111, the third switch circuit 104, the second power supply circuit 112, the fourth switch circuit 106, the first energy storage circuit 107, the bidirectional DC-DC converter circuit 130, the second energy storage circuit 108, the drive circuit 160 and the generator circuit 180 constitute the high-voltage circuit of the whole vehicle, realizing the power supply and drive of the whole vehicle.

[0093] S220, the first switch circuit 101, the third switch circuit 104 and the fourth switch circuit 106 are all disconnected, and the second switch circuit 102 is closed and turned on, so that the first power supply circuit 111, the first energy storage circuit 107, the bidirectional DC-DC converter circuit 130, the second energy storage circuit 108, the drive circuit 160, the generator circuit 180 and the second switch circuit 102 constitute the high voltage circuit of the whole vehicle, realizing the power supply and drive of the whole vehicle.

[0094] S230, the control second switch circuit 102 and the third switch circuit 104 are both disconnected, and the first switch circuit 101 and the fourth switch circuit 106 are closed and connected, so that the second power supply circuit 112, the first switch circuit 101, the bidirectional DC-DC converter circuit 130, the second energy storage circuit 108, the drive circuit 160, the power generation circuit 180, the first energy storage circuit 107 and the fourth switch circuit 106 constitute the high-voltage circuit of the whole vehicle, realizing the power supply and drive of the whole vehicle.

[0095] In summary, the battery self-heating system provided in this application divides the vehicle battery into a first power circuit 111 and a second power circuit 112 via the third switching unit K5. The first power circuit 111 is electrically connected to the first storage capacitor C1 via the second switching unit K4, and the second power circuit 112 is electrically connected to the second storage capacitor C2 via the first switching unit K1. This allows each of the first and second power circuits 111 and 112 to be charged and discharged once, meaning the vehicle power battery is charged and discharged twice, completing one heating cycle for the battery self-heating system, thus improving its heating efficiency. Furthermore, due to the high power of the bidirectional DC converter circuit 130 and its non-isolated topology design, the power devices have strong overcurrent capabilities, and the effective self-heating current can reach over 100A, thereby increasing the heating rate of the battery self-heating system. Therefore, the battery self-heating system of this application solves the problems of high cost and poor safety caused by the need for power batteries to be heated during the charging and discharging process in low-temperature environments in traditional technologies. At the same time, by controlling the charging and discharging current, the heating power can be adjusted in real time, and the heating time can be controlled as needed.

[0096] This application also provides a vehicle, including the above-mentioned... Figures 2 to 9 The battery self-heating system 100 in the illustrated embodiment may include the above-described features. Figure 1 The power drive system in the illustrated embodiment. The vehicle provided in this application includes the above-described... Figures 2 to 9 The battery self-heating system 100 in the illustrated embodiment can have the beneficial effects described in the above embodiments.

[0097] Furthermore, in the vehicle provided in this application, the battery self-heating system completes one heating cycle by charging and discharging once each through the first power circuit 111 and the second power circuit 112, i.e., the entire vehicle's power battery is charged and discharged twice. This improves the heating efficiency of the battery self-heating system. Simultaneously, due to the high power of the bidirectional DC-DC converter circuit 130 and its non-isolated topology design, the power devices have strong overcurrent capabilities, and the effective self-heating current of the battery can reach over 100A, thus increasing the heating rate of the battery self-heating system. Moreover, the third switching circuit 104 can divide the vehicle battery into the first power circuit 111 and the second power circuit 112 as power batteries to provide power to the entire battery self-heating system 100. This eliminates the need for two different power batteries, and since the first power circuit 111 and the second power circuit 112, as power batteries with the same medium, have similar heating effects, the complexity of the battery management and control system is reduced. This eliminates the need for additional DC-DC voltage conversion devices, reduces the number of power devices used, saves circuit costs, reduces the complexity of the high-voltage system, and improves system reliability. Therefore, the battery self-heating system of this application solves the problems of high cost and poor safety caused by the need for power batteries to be heated during the charging and discharging process in low-temperature environments in traditional technologies. At the same time, by controlling the charging and discharging current, the heating power can be adjusted in real time, and the heating time can be controlled as needed.

[0098] The flowchart described in this invention is merely one embodiment, and various modifications and variations can be made to this illustration or the steps in this invention without departing from the spirit of the invention. For example, these steps can be performed in different orders, or certain steps can be added, deleted, or modified. Those skilled in the art will understand that implementing all or part of the processes of the above embodiments, and making equivalent changes in accordance with the claims of this invention, still falls within the scope of the invention.

[0099] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A battery self-heating system, characterized by, include: The system comprises a first switching circuit, a second switching circuit, a third switching circuit, a fourth switching circuit, a first energy storage circuit, a second energy storage circuit, a first power supply circuit, a second power supply circuit, and a bidirectional DC-DC converter circuit. One end of the first switching circuit is electrically connected to the positive terminal of the second power supply circuit and the third switching circuit. The other end of the first switching circuit is electrically connected to the bidirectional DC-DC converter circuit. One end of the second switching circuit is electrically connected to the negative terminal of the first power supply circuit and the third switching circuit. The other end of the second switching circuit is electrically connected to both the first energy storage circuit and the bidirectional DC-DC converter circuit. The third switching circuit is electrically connected between the first power supply circuit and the second power supply circuit. One end of the fourth switching circuit is electrically connected to the negative terminal of the second power supply circuit. The other end of the fourth switching circuit is electrically connected to both the first energy storage circuit and the bidirectional DC-DC converter circuit. The first energy storage circuit is electrically connected to both the first power supply circuit and the bidirectional DC-DC converter circuit. The second energy storage circuit is electrically connected to both the second power supply circuit and the bidirectional DC-DC converter circuit. The bidirectional DC-DC converter circuit is electrically connected to both the first power supply circuit and the second power supply circuit.

2. The battery self-heating system of claim 1, wherein, The first power supply circuit and the second power supply circuit constitute a complete battery pack.

3. The battery self-heating system of claim 1, wherein, The bidirectional DC-DC converter circuit includes a bridge arm converter and a reactor. The bridge arm converter includes an N-phase bridge arm. The first ends of the N-phase bridge arms are connected to form a first bus terminal of the bridge arm converter, and the second ends of the N-phase bridge arms are connected to form a second bus terminal of the bridge arm converter. The first bus terminal of the bridge arm converter is electrically connected to the positive terminal of the second power supply circuit, and the second bus terminal of the bridge arm converter is electrically connected to the negative terminal of the second power supply circuit. The reactor includes an N-phase coil. The first end of the N-phase coil is electrically connected to the midpoint of the bridge arm converter, and the second end of the N-phase coil is connected to the first power supply circuit.

4. The battery self-heating system of claim 3, wherein, The bridge arm converter includes two phase bridge arms, each phase bridge arm including an upper bridge arm and a lower bridge arm. The two upper bridge arms each include a first power switch unit and a third power switch unit, and the two lower bridge arms each include a second power switch unit and a fourth power switch unit. The first end of the first power switch unit and the first end of the third power switch unit are connected together to form the first bus terminal of the bridge arm converter. The second end of the second power switch unit and the second end of the fourth power switch unit are connected together to form the second bus terminal of the bridge arm converter. The second end of the first power switch unit is electrically connected to the first end of the second power switch unit, and the second end of the third power switch unit is electrically connected to the first end of the fourth power switch unit. The reactor includes a first coil and a second coil, wherein a first end of the first coil is electrically connected to a first midpoint of the bridge arm converter, a first end of the second coil is electrically connected to a second midpoint of the bridge arm converter, and a second end of the first coil is shared with a second end of the second coil and electrically connected to a first end of the first energy storage circuit.

5. A control method of a battery self-heating system, applied to the battery self-heating system according to any one of claims 1 to 4, characterized in that, The control method includes: The third switch circuit is disconnected to separate the vehicle's battery pack into a first power circuit and a second power circuit. The first power supply circuit and / or the second power supply circuit are controlled to charge and discharge in a self-heating state by a bidirectional DC-DC converter circuit.

6. The method of claim 5, wherein the battery self-heating system is controlled by the controller based on the temperature of the battery and the temperature of the battery compartment. The step of controlling the charging and discharging of the first power supply circuit and / or the second power supply circuit through a bidirectional DC-DC converter circuit to achieve a self-heating state includes: Control the first power supply circuit to discharge so as to store energy in the first coil and the second coil in the bidirectional DC-DC converter circuit; Control the first power circuit, the first coil and the second coil to discharge, so as to charge the second power circuit, the first energy storage circuit and the second energy storage circuit; Control the second power supply circuit and the second energy storage circuit to discharge, so as to charge the first power supply circuit, the first coil, the second coil and the first energy storage circuit; The first coil and the second coil are controlled to discharge in order to charge the first power supply circuit.

7. A power drive system characterized by, include: The driving circuit, the power generation circuit, and the battery self-heating system as described in any one of claims 1-4, wherein the driving circuit is electrically connected to the second energy storage circuit of the battery self-heating system and the bidirectional DC-DC converter circuit; and the power generation circuit is electrically connected to the driving circuit.

8. The power drive system of claim 7, wherein, The battery self-heating system further includes a pre-charge switch circuit, which is electrically connected to the positive terminal of the first power supply circuit and the first energy storage circuit of the battery self-heating system, and is used to pre-charge the first energy storage circuit and the second energy storage circuit.

9. The power drive system of claim 7, wherein, The drive circuit includes an M-phase bridge arm, with the first ends of the M-phase bridge arm connected together to form a third bus terminal, and the second ends of the M-phase bridge arm connected together to form a fourth bus terminal. The third bus terminal of the drive circuit is electrically connected to the first bus terminal of the bridge arm converter of the bidirectional DC-DC converter, and the fourth bus terminal of the drive circuit is electrically connected to the second bus terminal of the bridge arm converter.

10. The power drive system of claim 9, wherein, The power generation circuit includes a W-phase bridge arm, with the first end of the W-phase bridge arm connected to form a fifth bus terminal and the second end of the W-phase bridge arm connected to form a sixth bus terminal. The fifth bus terminal of the power generation circuit is electrically connected to the third bus terminal of the drive circuit, and the sixth bus terminal of the power generation circuit is electrically connected to the fourth bus terminal of the drive circuit, for the purpose of realizing vehicle power generation.

11. A control method of a power drive system, applied to the power drive system according to any one of claims 7 to 10, characterized in that, The control method includes: The third switch circuit is controlled to open or close to separate or combine the first power circuit and the second power circuit into the vehicle's battery pack. Under the control of the first switching circuit, the second switching circuit, and the fourth switching circuit, the first power supply circuit and / or the second power supply circuit are controlled by the bidirectional DC-DC converter circuit in conjunction with the drive circuit and the generator circuit to realize the power supply and drive of the whole vehicle.

12. The control method of the power drive system according to claim 11, characterized by, Under the control of the first switching circuit, the second switching circuit, and the fourth switching circuit, the first power supply circuit and / or the second power supply circuit are controlled by a bidirectional DC-DC converter circuit in conjunction with a drive circuit and a generator circuit to achieve vehicle power-on and vehicle drive, including: The first and second switching circuits are both disconnected, while the third and fourth switching circuits are closed and connected, so that the first power supply circuit, the third switching circuit, the second power supply circuit, the fourth switching circuit, the first energy storage circuit, the bidirectional DC-DC converter circuit, the second energy storage circuit, the drive circuit, and the generator circuit constitute the high-voltage circuit of the whole vehicle, realizing the power supply and drive of the whole vehicle.

13. The control method of the power drive system according to claim 11, characterized by, Under the control of the first switching circuit, the second switching circuit, and the fourth switching circuit, the first power supply circuit and / or the second power supply circuit are controlled by a bidirectional DC-DC converter circuit in conjunction with a drive circuit and a generator circuit to achieve vehicle power-on and vehicle drive, including: The first, third, and fourth switch circuits are all disconnected, while the second switch circuit is closed and conducting, so that the first power supply circuit, the first energy storage circuit, the bidirectional DC-DC converter circuit, the second energy storage circuit, the drive circuit, the generator circuit, and the second switch circuit constitute the high-voltage circuit of the whole vehicle, realizing the power supply and driving of the whole vehicle.

14. The control method of the power drive system according to claim 11, characterized by, Under the control of the first switching circuit, the second switching circuit, and the fourth switching circuit, the first power supply circuit and / or the second power supply circuit are controlled by a bidirectional DC-DC converter circuit in conjunction with a drive circuit and a generator circuit to achieve vehicle power-on and vehicle drive, including: The second and third switch circuits are both disconnected, while the first and fourth switch circuits are closed and connected, so that the second power supply circuit, the first switch circuit, the bidirectional DC-DC converter circuit, the second energy storage circuit, the drive circuit, the power generation circuit, the first energy storage circuit, and the fourth switch circuit constitute the high-voltage circuit of the whole vehicle, realizing the power supply and drive of the whole vehicle.

15. A vehicle characterized by comprising: It includes the battery self-heating system as described in any one of claims 1 to 4, or the power drive system as described in any one of claims 7 to 10.

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