High-voltage pre-charging device, new energy electric vehicle, and control method for pre-charging circuit

Abstract

The present invention discloses a high-voltage pre-charging device, a new energy electric vehicle, and a control method for a pre-charging circuit. The high-voltage pre-charging device includes a high-voltage pre-charging circuit and a high-voltage filter. The high-voltage pre-charging circuit is used to prevent reverse polarity and buffer the voltage received from the battery high-voltage power supply; the high-voltage filter is connected to the high-voltage pre-charging circuit to filter out high- and low-frequency interference signals of the buffered voltage. The present invention solves the technical problems of relay adhesion, excessive inrush current, and damage to pre-charging resistors in thermal management systems.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to a high-voltage pre-charging device, a new energy electric vehicle, and a control method for a pre-charging circuit. Background Art

[0002] In new energy vehicle systems, the power battery thermal management system (TMS or unit) is used to cool the battery pack. This system includes a compressor. Because the compressor requires a high-voltage capacitor, a high-voltage pre-charge device is installed within the thermal management unit to prevent the high current surge generated when the unit's high voltage is powered on. However, existing thermal management systems are prone to problems such as relay sticking, excessive inrush current, and damage to the pre-charge resistor.

[0003] To address the above-mentioned problems, no effective solutions have been proposed so far. Summary of the Invention

[0004] The embodiments of the present invention provide a high-voltage pre-charging device, a new energy electric vehicle, and a control method for a pre-charging circuit, so as to at least solve the technical problems of relay adhesion, excessive inrush current, and damage to the pre-charging resistor in the thermal management system.

[0005] According to one aspect of an embodiment of the present invention, a high-voltage pre-charging device is provided, including: a high-voltage pre-charging circuit, used to prevent reverse connection of positive and negative poles and to buffer the voltage received from the high-voltage power supply of the battery; a high-voltage filter, connected to the high-voltage pre-charging circuit, used to filter out high and low frequency interference signals of the buffered voltage.

[0006] Optionally, the high-voltage pre-charging circuit includes: a high-voltage fuse module, a pre-charging relay, a main positive relay, an anti-reverse polarity diode and a pre-charging resistor, wherein the first end of the high-voltage fuse module is used to connect to the battery, the second end of the high-voltage fuse module is respectively connected to the first end of the pre-charging relay and the first end of the main positive relay, the second end of the pre-charging relay is connected to the first end of the anti-reverse polarity diode, the first end of the pre-charging resistor is connected to the second end of the anti-reverse polarity diode, and the second end of the pre-charging resistor is connected in parallel with the second end of the main positive relay to form the first output end of the high-voltage pre-charging circuit.

[0007] Optionally, the high-voltage pre-charging circuit further includes: a main negative relay, wherein a first end of the main negative relay is used to be connected to a battery, and a second end of the main negative relay serves as a second output end of the high-voltage pre-charging circuit.

[0008] Optionally, the high-voltage pre-charge circuit further includes: a pre-charge capacitor, wherein a first end of the pre-charge capacitor is connected to the first output end of the high-voltage pre-charge circuit, and a second end of the pre-charge capacitor is connected to the second output end of the high-voltage pre-charge circuit.

[0009] Optionally, the high-voltage filter includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a common-mode inductor, wherein the first input end of the common-mode inductor is connected to the first output end of the high-voltage pre-charging circuit, the second input end of the common-mode inductor is connected to the second output end of the high-voltage pre-charging circuit, the first end of the first capacitor is connected to the first input end of the common-mode inductor, the second end of the first capacitor is connected to the second input end of the common-mode inductor, the first end of the second capacitor is connected to the first output end of the common-mode inductor, the second end of the second capacitor is connected to the second output end of the common-mode inductor, the first end of the third capacitor is connected to the second input end of the common-mode inductor, the first end of the fourth capacitor is connected to the second output end of the common-mode inductor, and the second end of the third capacitor and the second end of the fourth capacitor are grounded.

[0010] According to another aspect of an embodiment of the present invention, a new energy electric vehicle is provided, comprising a unit for cooling a battery pack, wherein the unit comprises any one of the high-voltage pre-charging devices described above.

[0011] According to another aspect of an embodiment of the present invention, a control method for a pre-charging circuit is also provided, wherein the pre-charging circuit comprises: a high-voltage pre-charging device as described in any one of the above; a controller, communicatively connected to the high-voltage pre-charging device, for controlling the high-voltage pre-charging device to perform the following steps: obtaining a feedback voltage value and a voltage difference of the unit, wherein the voltage difference is the difference between the voltage value sent by the controller message and the power-on voltage threshold; when the feedback voltage value is less than the voltage difference, controlling the pre-charging relay and the main negative relay to close; and when the preset pre-charging conditions are met, controlling the main positive relay to close.

[0012] Optionally, the control method also includes: when the feedback voltage value is greater than or equal to the voltage difference, delaying according to a first preset time; if the feedback voltage value after the delay is greater than or equal to the voltage difference, a bonding fault occurs in the pre-charging circuit; if the feedback voltage value after the delay is less than the voltage difference, controlling the pre-charging relay and the main negative relay to close.

[0013] Optionally, the voltage difference includes at least: a first voltage difference, a second voltage difference and a third voltage difference. When the preset pre-charge condition is met, the main positive relay is controlled to close, including: delaying according to the second preset time, and if the feedback voltage value after the delay is greater than the first voltage difference, delaying according to the third preset time, and if the feedback voltage value after the delay is greater than the second voltage difference, delaying according to the fourth preset time, and if the feedback voltage value after the delay is greater than the third voltage difference, controlling the main positive relay to close.

[0014] Optionally, the voltage difference includes at least: a first voltage difference, a second voltage difference and a third voltage difference, and the control method further includes: delaying according to a second preset time, and if the feedback voltage value after the delay is less than or equal to the first voltage difference, the pre-charging fails; or, delaying according to a third preset time, and if the feedback voltage value after the delay is less than or equal to the second voltage difference, the pre-charging fails; or, delaying according to a fourth preset time, and if the feedback voltage value after the delay is less than or equal to the third voltage difference, the pre-charging fails.

[0015] Optionally, the control method also includes: when the preset pre-charging conditions are met and the delay according to the fourth preset time has been completed, continuing to delay according to the fifth preset time; disconnecting the main positive relay after the fifth preset time delay is completed; continuing to delay according to the sixth preset time, disconnecting the pre-charging relay, and pre-charging is completed.

[0016] In an embodiment of the present invention, the high-voltage pre-charging device used includes a high-voltage pre-charging circuit and a high-voltage filter, wherein the high-voltage pre-charging circuit is used to prevent the positive and negative poles from being reversed and to buffer the voltage received from the high-voltage power supply of the battery; the high-voltage filter is connected to the high-voltage pre-charging circuit and is used to filter out the high and low-frequency interference signals of the buffered voltage. The high-voltage pre-charging device can effectively avoid relay adhesion, excessive impact current, and damage to the pre-charging resistor, thereby achieving the technical effect of improving the reliability, maintainability and controllability of the thermal management system, and thus solving the technical problem that the thermal management system is prone to relay adhesion, excessive impact current, and damage to the pre-charging resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 is a schematic diagram of a high-voltage pre-charging device according to an embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of a high-voltage pre-charging device according to an optional embodiment of the present invention;

[0020] Figure 3 is a flow chart of a method for controlling a pre-charging circuit according to an optional embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] Example 1

[0024] According to one aspect of an embodiment of the present invention, a high-voltage pre-charging device is provided. Figure 1 Schematic diagram of a high-voltage pre-charging device according to an embodiment of the present invention. Figure 1 As shown, the high-voltage pre-charging device includes: a high-voltage pre-charging circuit 10 and a high-voltage filter 12, wherein the high-voltage pre-charging circuit 10 is used to prevent the positive and negative poles from being reversed and to buffer the voltage received from the battery high-voltage power supply; the high-voltage filter 12 is connected to the high-voltage pre-charging circuit 10 and is used to filter out high and low frequency interference signals of the buffered voltage.

[0025] It should be noted that the above-mentioned high-pressure pre-charging device is arranged in the thermal management system.

[0026] In the above embodiment, the high-voltage pre-charging device can effectively avoid relay adhesion, excessive inrush current, and damage to the pre-charging resistor, thereby achieving the technical effect of improving the reliability, maintainability and controllability of the thermal management system, and further solving the technical problems of the thermal management system that are prone to relay adhesion, excessive inrush current, and damage to the pre-charging resistor.

[0027] Optionally, the high-voltage pre-charging circuit 10 includes: a high-voltage fuse module, a pre-charging relay, a main positive relay, an anti-reverse polarity diode and a pre-charging resistor, wherein the first end of the high-voltage fuse module is used to connect to the battery, the second end of the high-voltage fuse module is respectively connected to the first end of the pre-charging relay and the first end of the main positive relay, the second end of the pre-charging relay is connected to the first end of the anti-reverse polarity diode, the first end of the pre-charging resistor is connected to the second end of the anti-reverse polarity diode, and the second end of the pre-charging resistor is connected in parallel with the second end of the main positive relay to form the first output end of the high-voltage pre-charging circuit 10.

[0028] Optionally, the high-voltage pre-charging circuit 10 further includes: a main negative relay, wherein a first end of the main negative relay is used to be connected to the battery, and a second end of the main negative relay serves as a second output end of the high-voltage pre-charging circuit 10 .

[0029] Optionally, the high-voltage pre-charging circuit 10 further includes: a pre-charging capacitor, wherein a first end of the pre-charging capacitor is connected to the first output end of the high-voltage pre-charging circuit 10 , and a second end of the pre-charging capacitor is connected to the second output end of the high-voltage pre-charging circuit 10 .

[0030] Optionally, the high-voltage filter 12 includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a common-mode inductor, wherein the first input end of the common-mode inductor is connected to the first output end of the high-voltage pre-charging circuit 10, the second input end of the common-mode inductor is connected to the second output end of the high-voltage pre-charging circuit 10, the first end of the first capacitor is connected to the first input end of the common-mode inductor, the second end of the first capacitor is connected to the second input end of the common-mode inductor, the first end of the second capacitor is connected to the first output end of the common-mode inductor, the second end of the second capacitor is connected to the second output end of the common-mode inductor, the first end of the third capacitor is connected to the second input end of the common-mode inductor, the first end of the fourth capacitor is connected to the second output end of the common-mode inductor, and the second end of the third capacitor and the second end of the fourth capacitor are grounded.

[0031] Example 2

[0032] According to another aspect of an embodiment of the present invention, a new energy electric vehicle is provided, comprising a unit for cooling a battery pack, wherein the unit comprises any one of the above-mentioned high-voltage pre-charging devices.

[0033] The types of new energy electric vehicles mentioned above include but are not limited to logistics vehicles, heavy trucks, light trucks, etc. Power batteries are used for power supply in new energy electric vehicles. The cooling of the power batteries involved in the present invention adopts an external power battery thermal management system (TMS controller for short). Its control circuit integrates multiple modules such as high-voltage pre-charging device, DCDC module and wireless module, thereby greatly improving the reliability, maintainability and intelligent controllability of the product.

[0034] It should be noted that the TMS (thermal management system) is mainly a battery thermal management unit, including a compressor, fan, electronic water pump, etc.; the TMS controller is the controller of the battery thermal management unit.

[0035] Example 3

[0036] According to another aspect of an embodiment of the present invention, a control method for a pre-charging circuit is also provided, and the pre-charging circuit includes: a high-voltage pre-charging device of any one of the above items; a controller, which is communicatively connected to the high-voltage pre-charging device, and is used to control the high-voltage pre-charging device to perform the following steps: obtaining the feedback voltage value and voltage difference of the unit, wherein the voltage difference is the difference between the voltage value sent by the controller message and the power-on voltage threshold; when the feedback voltage value is less than the voltage difference, controlling the pre-charging relay and the main negative relay to close; and when the preset pre-charging conditions are met, controlling the main positive relay to close.

[0037] Optionally, the above control method also includes: when the feedback voltage value is greater than or equal to the voltage difference, delaying according to a first preset time; if the feedback voltage value after the delay is greater than or equal to the voltage difference, a bonding fault occurs in the pre-charging circuit; if the feedback voltage value after the delay is less than the voltage difference, controlling the pre-charging relay and the main negative relay to close.

[0038] Optionally, the voltage difference includes at least: a first voltage difference, a second voltage difference and a third voltage difference. When the preset pre-charging conditions are met, the main positive relay is controlled to close, including: delaying according to the second preset time, and if the feedback voltage value after the delay is greater than the first voltage difference, delaying according to the third preset time, and if the feedback voltage value after the delay is greater than the second voltage difference, delaying according to the fourth preset time, and if the feedback voltage value after the delay is greater than the third voltage difference, controlling the main positive relay to close.

[0039] Optionally, the voltage difference includes at least: a first voltage difference, a second voltage difference and a third voltage difference, and the above control method also includes: delaying according to a second preset time, and if the feedback voltage value after the delay is less than or equal to the first voltage difference, the pre-charging fails; or, delaying according to a third preset time, and if the feedback voltage value after the delay is less than or equal to the second voltage difference, the pre-charging fails; or, delaying according to a fourth preset time, and if the feedback voltage value after the delay is less than or equal to the third voltage difference, the pre-charging fails.

[0040] Optionally, the above control method also includes: when the preset pre-charging conditions are met and the delay according to the fourth preset time has been completed, continuing to delay according to the fifth preset time; disconnecting the main positive relay after the fifth preset time delay is completed; continuing to delay according to the sixth preset time, disconnecting the pre-charging relay, and pre-charging is completed.

[0041] An optional implementation manner of the present invention is described in detail below.

[0042] Figure 2 Schematic diagram of a high-voltage pre-filling device according to an optional embodiment of the present invention. Figure 2 As shown, the high-voltage pre-charging device can be composed of a high-voltage pre-charging circuit and a high-voltage filter. Among them, the high-voltage pre-charging circuit integrates a FUSE high-voltage fuse, a K1 pre-charging relay, a K2 main positive relay, a K3 main negative relay, a D1 anti-reverse polarity diode, an Rs pre-charging resistor and a C1 pre-charging capacitor. The high-voltage filter is composed of an X1 capacitor, an X2 capacitor, a Y1 capacitor, a Y2 capacitor and an L common-mode inductor. It should be noted that the high-voltage pre-charging circuit can avoid the high-voltage instantaneous high-current impact on the high-voltage components, and prevent the high-voltage line fuse, compressor and other high-voltage equipment from being damaged by the impact current; the D1 anti-reverse polarity diode of the high-voltage pre-charging circuit can prevent the high-voltage positive and negative poles from being reversed; the high-voltage filter can filter out high and low-frequency interference of the high-voltage line and improve the electromagnetic compatibility of the product.

[0043] Figure 3 : is a flow chart of a control method for a pre-charging circuit according to an optional embodiment of the present invention. Figure 3 As shown, the closing of the pre-charge circuit is divided into multiple steps and is determined by the values ​​of three parameters:

[0044] 1) The voltage value (BMS_HV) sent by the BMS (vehicle battery management controller) message;

[0045] 2) The voltage value of the high-voltage feedback inside the unit (COMP_HV);

[0046] 3) Power-on voltage threshold (HV_Threshold) set by software;

[0047] Wherein, (POWER_ON_BMS_HV) is the difference between the (BMS_HV) voltage and the (HV_Threshold) voltage; T represents time, T=RC, C is the size of the pre-charge capacitor, and R is the size of the pre-charge resistor.

[0048] The pre-charging circuit has a set of power-on logic. The specific power-on logic is described as follows:

[0049] When the high voltage command is received from the BMS, pre-charging starts.

[0050] ①When (COMP_HV) is less than (POWER_ON_BMS_HV);

[0051] Close the K1 pre-charge relay and the K3 main negative relay (i.e., the auxiliary relay, which is connected in series to the pre-charge resistor to control the pre-charge current to be less than 500mA);

[0052] ②When (COMP_HV) is greater than or equal to (POWER_ON_BMS_HV);

[0053] Delay 8T until (COMP_HV) is less than (POWER_ON_BMS_HV). Otherwise, it is judged as a sticking fault and pre-charging is not continued.

[0054] ③After the first 2T delay;

[0055] Determine whether the compressor feedback value COMP_HV is greater than POWER_ON_BMS_HV / 4. If so, continue charging; otherwise, pre-charging fails to prevent the subsequent wiring harness, compressor, or PTC from short-circuiting and continuing to supply high voltage power.

[0056] ④After the second 2T delay;

[0057] Determine whether the compressor feedback value COMP_HV is greater than POWER_ON_BMS_HV / 2. If so, continue; otherwise, pre-charge fails, which is a normal condition.

[0058] ⑤After 4T delay;

[0059] Determine whether the compressor feedback value COMP_HV is greater than POWER_ON_BMS_HV. If it is, delay for another 3T to close the K2 main positive relay. After a delay of 4T, the pre-charge capacitor charging has basically reached balance to prevent deviation of the internal AD sampling value.

[0060] ⑥ Delay another 1T to disconnect the pre-charge relay, and a complete pre-charge is completed.

[0061] In the above embodiment, the K1 pre-charging relay is closed for pre-charging, wherein the K2 main relay is disconnected, and the K3 main negative relay is closed; when the final set pressure difference is reached, the K1 pre-charging relay is closed for pre-charging, wherein the K2 main positive relay is closed and opened, and the K3 main negative relay remains closed; it should be noted that this embodiment can minimize the pre-charging pressure difference and reduce the impact current; in addition, since the current is charged in a parabolic manner, the initial current is very large, and this implementation step can prevent the pre-charging resistance from causing serious heat during the charging time, and charging can be stopped immediately if a fault is determined; in addition, the predetermined time is delayed to allow the pressure difference to further decrease or disappear, and then the K1 pre-charging relay is disconnected, and the K3 and K2 relays are kept closed, so that the pre-charging is completed; in addition, by setting multiple predetermined times, the pre-charging completion time is shortened.

[0062] It should be noted that the three steps can be divided into POWER_ON_BMS_HV / 4, POWER_ON_BMS_HV / 2 and POWER_ON_BMS_HV / 1. If any of the steps are not met, the process cannot proceed. This method is mainly used to prevent voltage abnormalities or pre-charge current failures, which may cause the pre-charge resistor to heat up and the inrush current to be large.

[0063] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0064] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0065] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only exemplary. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0066] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0067] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0068] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, etc. Various media that can store program codes.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high-pressure pre-filling device, characterized in that: include: A high-voltage pre-charging circuit, used to prevent reverse connection of the positive and negative poles and to buffer the voltage received from the battery high-voltage power supply, wherein the high-voltage pre-charging circuit includes: a first output end and a second output end; A high-voltage filter is connected to the high-voltage pre-charging circuit and is used to filter out high and low-frequency interference signals of the buffered voltage. The high-voltage filter includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a common-mode inductor, wherein the first input end of the common-mode inductor is connected to the first output end of the high-voltage pre-charging circuit, the second input end of the common-mode inductor is connected to the second output end of the high-voltage pre-charging circuit, the first end of the first capacitor is connected to the first input end of the common-mode inductor, the second end of the first capacitor is connected to the second input end of the common-mode inductor, the first end of the second capacitor is connected to the first output end of the common-mode inductor, the second end of the second capacitor is connected to the second output end of the common-mode inductor, the first end of the third capacitor is connected to the second input end of the common-mode inductor, the first end of the fourth capacitor is connected to the second output end of the common-mode inductor, and the second end of the third capacitor and the second end of the fourth capacitor are grounded.

2. The device according to claim 1, characterized in that The high-voltage pre-charging circuit includes: a high-voltage fuse module, a pre-charging relay, a main positive relay, an anti-reverse polarity diode and a pre-charging resistor, wherein the first end of the high-voltage fuse module is used to connect to the battery, the second end of the high-voltage fuse module is respectively connected to the first end of the pre-charging relay and the first end of the main positive relay, the second end of the pre-charging relay is connected to the first end of the anti-reverse polarity diode, the first end of the pre-charging resistor is connected to the second end of the anti-reverse polarity diode, and the second end of the pre-charging resistor is connected in parallel with the second end of the main positive relay to form the first output end of the high-voltage pre-charging circuit.

3. The device according to claim 2, characterized in that The high-voltage pre-charging circuit further includes: a main negative relay, wherein a first end of the main negative relay is used to be connected to a battery, and a second end of the main negative relay serves as a second output end of the high-voltage pre-charging circuit.

4. A new energy electric vehicle, comprising a unit for cooling a battery pack, characterized in that: The unit includes the high-pressure pre-charging device according to any one of claims 1 to 3.

5. The new energy electric vehicle according to claim 4, characterized in that: The high-voltage pre-charging circuit in the high-voltage pre-charging device further includes: a pre-charging capacitor, wherein a first end of the pre-charging capacitor is connected to a first output end of the high-voltage pre-charging circuit, and a second end of the pre-charging capacitor is connected to a second output end of the high-voltage pre-charging circuit.

6. A control method for a pre-charge circuit, characterized in that: The pre-charge circuit comprises: The high-pressure pre-charging device according to any one of claims 2 to 3; A controller is in communication with the high-pressure pre-filling device and is configured to control the high-pressure pre-filling device to perform the following steps: Obtaining a feedback voltage value and a voltage difference of the unit, wherein the voltage difference is the difference between the voltage value sent by the controller message and the power-on voltage threshold; When the feedback voltage value is less than the voltage difference value, controlling the pre-charge relay and the main negative relay to be closed; When the preset pre-charge conditions are met, the main positive relay is controlled to close.

7. The control method according to claim 6, characterized in that: The control method further includes: When the feedback voltage value is greater than or equal to the voltage difference value, delaying according to a first preset time; If the feedback voltage value after the delay is greater than or equal to the voltage difference, a sticking fault occurs in the pre-charging circuit; If the feedback voltage value after the delay is less than the voltage difference, the pre-charge relay and the main negative relay are controlled to close.

8. The control method according to claim 6, characterized in that: The voltage difference includes at least: a first voltage difference, a second voltage difference, and a third voltage difference. When a preset pre-charge condition is met, controlling the main positive relay to close includes: Delay according to the second preset time, if the feedback voltage value after the delay is greater than the first voltage difference, delay according to the third preset time, if the feedback voltage value after the delay is greater than the second voltage difference, delay according to the fourth preset time, if the feedback voltage value after the delay is greater than the third voltage difference, control the main positive relay to close.

9. The control method according to claim 6, characterized in that: The voltage difference includes at least a first voltage difference, a second voltage difference, and a third voltage difference. The control method further includes: If the delay is performed according to the second preset time and the feedback voltage value after the delay is less than or equal to the first voltage difference, the pre-charging fails; or, if the delay is performed according to the third preset time and the feedback voltage value after the delay is less than or equal to the second voltage difference, the pre-charging fails; or, if the delay is performed according to the fourth preset time and the feedback voltage value after the delay is less than or equal to the third voltage difference, the pre-charging fails.

10. The control method according to claim 8, characterized in that: The control method further includes: When the preset pre-charging conditions are met and the delay according to the fourth preset time has been completed, continue to delay according to the fifth preset time; after the fifth preset time delay is completed, disconnect the main positive relay; continue to delay according to the sixth preset time, disconnect the pre-charging relay, and pre-charging is completed.

11. The control method according to claim 6, characterized in that: The high-voltage pre-charging circuit in the high-voltage pre-charging device further includes: a pre-charging capacitor, wherein a first end of the pre-charging capacitor is connected to a first output end of the high-voltage pre-charging circuit, and a second end of the pre-charging capacitor is connected to a second output end of the high-voltage pre-charging circuit.

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