A control method for a vehicle high-voltage circuit

Abstract

This invention belongs to the field of high-voltage charging and discharging technology for new energy vehicles, specifically relating to a control method for a vehicle's high-voltage circuit. The method includes: acquiring control commands for charging / discharging the high-voltage circuit; switching the operating states of a switching unit and / or relay according to the control commands, so that a first battery pack and a second battery pack can begin charging or discharging via series / parallel connection; wherein, after the operating states of the switching unit and relay are switched, the voltage at sampling points on the high-voltage circuit is collected based on a preset reference point, and open-circuit fault diagnosis is performed on the sampling points and / or reference points based on the collected voltage. This invention can comprehensively diagnose open-circuit faults in the high-voltage circuit after different control commands are executed, causing corresponding actions of the switching unit and relay, thereby maintaining the safe and stable reliable operation of the high-voltage circuit.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage charging and discharging technology for new energy vehicles, and specifically relates to a control method for a vehicle's high-voltage circuit. Background Technology

[0002] With the rapid development of the new energy vehicle industry, in order to improve driving range and charging time, an 800V battery system platform has been launched based on the 400V battery system platform of the vehicle. The 800V battery system can effectively improve the driving range of the vehicle and shorten the charging time.

[0003] Currently, 800V battery systems require real-time monitoring of the voltage across high-voltage relays and fuses during operation to monitor system faults. However, high-voltage sampling for 800V battery systems is more complex than for 400V battery systems. Some Battery Management Systems (BMS) cannot provide comprehensive monitoring of 800V battery systems. When an open-circuit fault occurs in any part of the system, it can affect the normal operation of the battery pack, high-voltage relays, fuses, etc., and in severe cases, endanger the safety of the power battery pack and the entire vehicle.

[0004] Therefore, there is an urgent need for a control method for fault monitoring of vehicle 800V battery systems. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a fault detection method for a vehicle 800V battery system, which can comprehensively monitor open circuit faults in various circuits of the 800V battery system, thereby improving the safety and reliability of the vehicle 800V battery system.

[0006] To achieve the above and other related objectives, the present invention provides a control method for a vehicle high-voltage circuit. The high-voltage circuit includes: a first battery pack and a second battery pack, as well as multiple switching units and multiple relays; wherein, the positive terminal of the first battery pack is connected to the positive terminal of the second battery pack through a first switching unit, and is connected to the negative terminal of the second battery pack through a second switching unit, and the negative terminal of the first battery pack is connected to the negative terminal of the second battery pack through a third switching unit; one end of the main positive relay, the pre-charge relay, and the charging positive relay are all connected to the positive terminal of the second battery pack, the other end of the main positive relay and the pre-charge relay are used to connect to a load, and the other end of the charging positive relay serves as the DC charging positive terminal. The main negative relay and the charging negative relay are both connected at one end to the negative terminal of the second battery pack. The other end of the main negative relay is used to connect to the load, and the other end of the charging negative relay serves as the DC charging negative port. The control method includes: acquiring control commands for charging / discharging in the high-voltage circuit; driving the switching unit and / or relay to switch their operating states according to the control commands, so that the first battery pack and the second battery pack can start charging or discharging externally in series / parallel connection; wherein, after the operating states of the switching unit and the relay are switched, the voltage of the sampling point on the high-voltage circuit is collected based on a preset reference point, and open circuit fault diagnosis is performed on the sampling point and / or the reference point based on the collected voltage.

[0007] According to a specific embodiment of the present invention, when the control command is to apply high voltage or AC charging, based on the output voltage requirement or the input charging voltage, the first and third switching units are controlled to close, and the second switching unit is opened, so that the first battery pack and the second battery pack are discharged or charged in parallel; the pre-charge relay is sequentially controlled to close, the main negative relay is closed, the main positive relay is closed, and then the pre-charge relay is opened; wherein, after the first switching unit is closed, the voltage of the corresponding sampling point is collected based on a preset first reference point, and an open circuit fault diagnosis is performed on the first sampling point between the positive terminals of the first battery pack and the second battery pack; after both the first and third switching units are closed, the voltage of the corresponding sampling point is collected based on the preset first reference point. The voltage at the sampling point is collected, and an open-circuit fault diagnosis is performed on the second sampling point between the second battery pack and the main positive relay / pre-charge relay / charging positive relay; after the pre-charge relay is closed, the voltage at the corresponding sampling point is collected based on a preset first reference point, and an open-circuit fault diagnosis is performed on the third sampling point between the main positive relay / pre-charge relay and the load; after the main positive relay is closed, the voltage at the corresponding sampling point is collected based on a preset first reference point, and an open-circuit fault diagnosis is performed on the first reference point on the negative terminal of the first battery pack; after both the main positive relay and the main negative relay are closed, the voltage at the corresponding sampling point is collected based on a preset second reference point, and an open-circuit fault diagnosis is performed on the second reference point between the main negative relay and the load.

[0008] According to a specific embodiment of the present invention, when the control command is to apply high voltage or AC charging, based on the output voltage requirement or the input charging voltage, the second switching unit is controlled to close, and the first and third switching units are opened, so that the first battery pack and the second battery pack are discharged or charged in series; the pre-charge relay is sequentially controlled to close, the main negative relay is closed, the main positive relay is closed, and then the pre-charge relay is opened; wherein, after the second switching unit closes, the voltage of the corresponding sampling point is collected based on a preset first reference point, and an open circuit fault diagnosis is performed on the fourth sampling point between the positive terminal of the first battery pack and the negative terminal of the second battery pack, and the voltage of the second battery pack and the main positive relay are also checked. Open-circuit fault diagnosis is performed at the second sampling point between the main positive relay / pre-charge relay / positive charging relay; after the pre-charge relay is closed, the voltage of the corresponding sampling point is collected based on a preset first reference point, and open-circuit fault diagnosis is performed at the third sampling point between the main positive relay / pre-charge relay and the load; after the main positive relay is closed, the voltage of the corresponding sampling point is collected based on a preset first reference point, and open-circuit fault diagnosis is performed at the first reference point on the negative terminal of the first battery pack; after both the main positive relay and the main negative relay are closed, the voltage of the corresponding sampling point is collected based on a preset second reference point, and open-circuit fault diagnosis is performed at the second reference point between the main negative relay and the load.

[0009] According to a specific embodiment of the present invention, when the control command is DC charging, based on the output voltage requirement or the input charging voltage, the first and third switching units are controlled to close, and the second switching unit is opened, so that the first battery pack and the second battery pack are charged in parallel; the pre-charge relay is sequentially controlled to close, the main negative relay is closed, the main positive relay is closed, and then the pre-charge relay is opened, and the charging positive relay and the charging negative relay are closed; wherein, after the first switching unit is closed, the voltage of the corresponding sampling point is collected based on a preset first reference point, and an open circuit fault diagnosis is performed on the first sampling point between the positive terminal of the first battery pack and the positive terminal of the second battery pack; after both the first and third switching units are closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and an open circuit fault diagnosis is performed on the second sampling point between the second battery pack and the main positive relay / pre-charge relay / charging positive relay. The following steps are performed: After the pre-charge relay closes, the voltage at the corresponding sampling point is collected based on a preset first reference point, and an open-circuit fault diagnosis is performed on the third sampling point between the main positive relay / pre-charge relay and the load; after the main positive relay closes, the voltage at the corresponding sampling point is collected based on a preset first reference point, and an open-circuit fault diagnosis is performed on the first reference point on the negative terminal of the first battery pack; after both the main positive relay and the main negative relay close, the voltage at the corresponding sampling point is collected based on a preset second reference point, and an open-circuit fault diagnosis is performed on the second reference point between the main negative relay and the load; after the charging positive relay and the charging negative relay close, the voltage at the corresponding sampling point is collected based on a preset first reference point, and an open-circuit fault diagnosis is performed on the fifth sampling point between the charging positive relay and the DC charging positive port, and an open-circuit fault diagnosis is performed on the sixth sampling point between the charging negative relay and the DC charging negative port.

[0010] According to a specific embodiment of the present invention, when the control command is DC charging, based on the output voltage requirement or the input charging voltage, the second switching unit is controlled to close, and the first and third switching units are opened, so that the first battery pack and the second battery pack are charged in series; the pre-charge relay is sequentially controlled to close, the main negative relay is closed, the main positive relay is closed, the pre-charge relay is then opened, and the charging positive relay and the charging negative relay are closed; wherein, after the second switching unit is closed, the voltage of the corresponding sampling point is collected based on a preset first reference point, and an open circuit fault diagnosis is performed on the fourth sampling point between the positive terminal of the first battery pack and the negative terminal of the second battery pack, and an open circuit fault diagnosis is performed on the second sampling point between the second battery pack and the main positive relay / pre-charge relay / charging positive relay; after the pre-charge relay is closed, based on the preset first reference point... The system collects voltage data at corresponding sampling points and performs open-circuit fault diagnosis on the third sampling point between the main positive relay / pre-charge relay and the load. After the main positive relay closes, it collects voltage data at corresponding sampling points based on a preset first reference point and performs open-circuit fault diagnosis on the first reference point on the negative terminal of the first battery pack. After both the main positive relay and the main negative relay close, it collects voltage data at corresponding sampling points based on a preset second reference point and performs open-circuit fault diagnosis on the second reference point between the main negative relay and the load. After the charging positive relay and the charging negative relay close, it collects voltage data at corresponding sampling points based on a preset first reference point and performs open-circuit fault diagnosis on the fifth sampling point between the charging positive relay and the DC charging positive port, as well as on the sixth sampling point between the charging negative relay and the DC charging negative port.

[0011] According to a specific embodiment of the present invention, the high-voltage circuit further includes a fuse, which is connected in series between the main positive relay and the load.

[0012] According to a specific embodiment of the present invention, after the main positive relay is closed, the voltage of the corresponding sampling point is collected based on a preset first reference point, and an open circuit fault diagnosis is performed on the seventh sampling point at the rear end of the fuse.

[0013] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the seventh sampling point includes: acquiring the first voltage of the third sampling point at the rear end of the precharge relay / main positive relay and the second voltage of the seventh sampling point at the front end of the load based on a preset first reference point; if the first voltage is greater than a preset first voltage threshold and the second voltage is less than a preset second voltage threshold, then the seventh sampling point is considered to have an open circuit fault.

[0014] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the first sampling point includes: acquiring the first voltage of the first sampling point at the front end of the first switching unit and the second voltage of the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay based on a preset first reference point, and calculating their difference: if the difference is greater than a preset second voltage threshold and the first voltage is less than the preset second voltage threshold, then the first sampling point is considered to have an open circuit fault.

[0015] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the fourth sampling point includes: acquiring the first voltage of the fourth sampling point at the rear end of the second switching unit and the second voltage of the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay based on a preset first reference point; if the first voltage is less than a preset second voltage threshold and the second voltage is greater than a preset third voltage threshold, then the fourth sampling point is considered to have an open circuit fault.

[0016] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the second sampling point includes: acquiring the first voltage of the fourth sampling point at the rear end of the second switching unit and the second voltage of the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay based on a preset first reference point; if the first voltage is greater than a preset first voltage threshold and the second voltage is less than a preset second voltage threshold, then the second sampling point is considered to have an open circuit fault.

[0017] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the second sampling point includes: acquiring the first voltage of the first sampling point at the front end of the first switching unit and the second voltage of the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay based on a preset first reference point; if the first voltage is greater than a preset first voltage threshold and the second voltage is less than a preset second voltage threshold, then the second sampling point is considered to have an open circuit fault.

[0018] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the third sampling point includes: acquiring the first voltage of the third sampling point at the rear end of the precharge relay / main positive relay and the second voltage of the seventh sampling point at the front end of the load based on a preset first reference point; if the first voltage is less than a preset second voltage threshold and the second voltage is greater than a preset first voltage threshold, then the open circuit fault is considered to have occurred at the third sampling point.

[0019] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the first reference point includes: acquiring the first voltage of the first sampling point at the front end of the first switching unit, the second voltage of the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay, and the third voltage of the third sampling point at the rear end of the pre-charge relay / main positive relay based on the preset first reference point; if the first voltage, the second voltage, and the third voltage are all less than the preset second voltage threshold, then the first reference point is considered to have an open circuit fault.

[0020] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the second reference point includes: acquiring the first voltage of the first sampling point at the front end of the first switching unit and the second voltage of the third sampling point at the rear end of the precharge relay / main positive relay based on the preset second reference point; if both the first voltage and the second voltage are less than the preset second voltage threshold, then the second reference point is considered to have an open circuit fault.

[0021] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the fifth sampling point includes: acquiring the first voltage of the fifth sampling point at the rear end of the charging positive relay and the second voltage of the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay based on a preset first reference point; if the first voltage is less than a preset second voltage threshold and the second voltage is greater than a preset first voltage threshold, then the fifth sampling point is considered to have an open circuit fault.

[0022] According to a specific embodiment of the present invention, the open circuit fault diagnosis step of the sixth sampling point includes: collecting the voltage of the sixth sampling point at the rear end of the charging negative relay based on a preset first reference point; if the voltage is less than a preset second voltage threshold, the sixth sampling point is considered to have an open circuit fault.

[0023] This invention provides a control method for a vehicle high-voltage circuit, which can perform comprehensive open-circuit fault diagnosis on the high-voltage circuit after different control commands are executed and the switching unit and relays act accordingly, so as to maintain the safe and stable reliable operation of the high-voltage circuit. Attached Figure Description

[0024] Figure 1 A flowchart illustrating a specific embodiment of a vehicle high-voltage circuit control method provided by the present invention;

[0025] Figure 2 This is a schematic diagram of the circuit topology of a specific embodiment of the high-voltage circuit for vehicles provided by the present invention. Detailed Implementation

[0026] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0027] 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 belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0028] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0029] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0030] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0031] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0032] Please see Figure 1 As shown, a control method for a vehicle high-voltage circuit can be applied to the vehicle's 800V battery system, i.e., the vehicle high-voltage circuit mentioned in this embodiment. In practical applications, the high-voltage circuit can be used to supply power to electrical equipment on the vehicle or to charge the vehicle through a charging pile connected to the vehicle.

[0033] It is understood that although this embodiment is aimed at the current 800V voltage level battery system of vehicles, in the future, with the continuous development of the field of new energy vehicle power battery technology, the voltage level of vehicle battery systems will gradually increase, such as 1000V battery systems or 1200V battery systems, etc. The control method provided in this embodiment is also applicable. It can comprehensively monitor whether open circuit faults occur at multiple locations on the high voltage circuit of the vehicle, so as to maintain the safety and reliability of the battery system. No further restrictions are imposed on this. Modifications and refinements made by those skilled in the art to the embodiments of the present invention without departing from the spirit of the present invention still fall within the scope of the invention application patent of the present invention.

[0034] It should also be noted that the high-voltage circuit mentioned in this embodiment consists of at least a first battery pack, a second battery pack, and several switching units and relays. Since current development of vehicle battery systems is limited to an 800V voltage level, switching between 400V and 800V voltage can be achieved using two 400V battery packs. However, when a vehicle is equipped with battery systems of different voltage levels, or even higher voltage levels, the high-voltage circuit can be composed of more battery packs, not just two. Therefore, the vehicle high-voltage circuit control method provided in this embodiment is only used to illustrate the technical solution with an 800V battery system as a preferred example, and is not intended to limit the scope of application of the method.

[0035] For details, please refer to Figure 2 The high-voltage circuit of the vehicle shown includes battery pack 1 (the first battery pack), whose positive terminal is connected to battery pack 2 (the second battery pack) via a first switching unit S1. To protect the high-voltage circuit, a fuse (Fuse1) is connected in series between battery pack 1 and the first switching unit S1. Furthermore, the positive terminal of battery pack 1 is also connected to the negative terminal of battery pack 2 via a second switching unit S2. To suppress active power oscillations in the high-voltage circuit, an active fuse (PSS, Pyrotechnical safety switches) is connected in series between the second switching unit S2 and the negative terminal of battery pack 2. The negative terminal of battery pack 2 is also connected to the negative terminal of battery pack 1 via a third switching unit S2. Similarly, a fuse (Fuse2) is connected in series between the negative terminal of battery pack 2 and the third switching unit S3. Therefore, by controlling the closing and opening of the first switching unit S1, the second switching unit S2, and the third switching unit S3, battery packs 1 and 2 can be connected in series or parallel to discharge or charge, allowing the high-voltage circuit to switch between 400V and 800V.

[0036] Furthermore, one end of the main positive relay, pre-charge relay, and charging positive relay are all connected to the positive terminal of battery pack 2, and the other end of the main positive relay and pre-charge relay are used to connect to the load, while the other end of the charging positive relay serves as a DC charging positive port, which can be used for DC charging of battery pack 1 and battery pack 2. One end of the main negative relay and charging negative relay are both connected to the negative terminal of battery pack 2, and the other end of the main negative relay is used to connect to the load, while the other end of the charging negative relay serves as a DC charging negative port. Meanwhile, to protect the safety of the high-voltage line and prevent overcurrent from burning out the line or load, a fuse Fuse3 is connected in series between the main positive relay and the load.

[0037] Based on the above-described high-voltage circuit, the control method for the vehicle high-voltage circuit in this embodiment specifically includes:

[0038] Step S100: Obtain control commands for charging / discharging from the high-voltage circuit, such as vehicle high voltage connection, high voltage disconnection, AC charging, DC charging, etc.

[0039] Step S200: The operating states of the drive unit and / or relay are switched according to the control command, so that the first battery pack and the second battery pack begin charging or discharging via series / parallel connection. It is understood that when the vehicle is connected to high voltage, or when charging begins, it is necessary to control the series or parallel connection of battery pack 1 and battery pack 2 according to the output or input voltage level to meet actual needs. Therefore, the corresponding switch unit and relay are controlled to operate, i.e., to close and close.

[0040] In this process, after the operating states of the switching unit and the relay are switched, the voltage at a sampling point on the high-voltage circuit is collected based on a preset reference point, and open-circuit fault diagnosis is performed on the sampling point and / or the reference point according to the collected voltage. It is understood that the closing times of the switching unit and the relay differ depending on the different operating states of the high-voltage circuit. Therefore, after a certain switching unit or relay closes, an open-circuit fault diagnosis can be performed on its corresponding line, i.e., the sampling point, to ensure that the switching unit or relay and its corresponding line are operating normally and without faults after closure, thereby improving the safety and reliability of the high-voltage circuit.

[0041] Specifically, when the control command is to apply high voltage or perform AC charging, based on the required output voltage or input charging voltage (e.g., a 400V voltage requirement), the first switch unit S1 and the third switch unit S3 are closed, while the second switch unit S2 is opened, allowing battery pack 1 and battery pack 2 to discharge or charge in parallel. It's understandable that connecting only battery pack 1 or battery pack 2 to the high-voltage circuit would also meet the requirement, but this is not typically done and will not be discussed further. Alternatively, if an 800V voltage requirement is required, the second switch unit S2 is closed, while the first switch unit S1 and the third switch unit S3 are opened, allowing battery pack 1 and battery pack 2 to discharge or charge in series.

[0042] Furthermore, the pre-charge relay is closed sequentially, followed by the main negative relay, then the main positive relay, and finally the pre-charge relay is disconnected.

[0043] Therefore, when a vehicle starts to connect to high voltage or AC charging, multiple switching units and relays need to be closed. Accordingly, after the corresponding switching unit or relay is closed, open circuit fault diagnosis can be performed on the corresponding sampling point to maintain the safe and stable operation of the high voltage circuit.

[0044] In one specific embodiment, it can be as follows Figure 2 As shown, after the first switching unit S1 is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point R1, and an open-circuit fault diagnosis is performed on the first sampling point V1 between the positive terminals of battery pack 1 and battery pack 2. Specifically, based on the first reference point R1, the first voltage of the first sampling point V1 at the front end of the first switching unit S1 and the second voltage of the second sampling point V3 at the front end of the main positive relay / pre-charge relay / charging positive relay are collected, and their difference is calculated: if the difference is greater than the preset second voltage threshold and the first voltage is less than the preset second voltage threshold, then the first sampling point V1 is considered to have an open-circuit fault. For example, if both battery pack 1 and battery pack 2 are 400V, then when the voltage deviation is greater than 50V and the first voltage is less than 50V, V1 is considered to have an open-circuit fault. At the same time, when the first voltage is greater than 150V, V1 is considered to be normal.

[0045] After the second switching unit S2 is closed, the voltage at the corresponding sampling point is collected based on the preset first reference point R1, and an open-circuit fault diagnosis is performed on the fourth sampling point between the positive terminal of battery pack 1 and the negative terminal of battery pack 2. Specifically, based on the first reference point R1, the first voltage of the fourth sampling point V2 at the rear end of the second switching unit S2 and the second voltage of the second sampling point V3 at the front end of the main positive relay / pre-charge relay / charging positive relay are collected: if the first voltage is less than the preset second voltage threshold and the second voltage is greater than the preset third voltage threshold, then the fourth sampling point V2 is considered to have an open-circuit fault. For example, if both battery pack 1 and battery pack 2 are 400V, then V2 is considered to have an open-circuit fault when the first voltage is less than 50V and the second voltage is greater than 300V. At the same time, V2 is considered to be normal when the first voltage is greater than 150V.

[0046] Furthermore, after both the first switch unit S1 and the third switch unit S3 are closed, or after the second switch unit S2 is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point R1, and an open-circuit fault diagnosis is performed on the second sampling point V3 between the battery pack 2 and the main positive relay / pre-charge relay / charging positive relay. Specifically, after both the first switch unit S1 and the third switch unit S3 are closed, the first voltage of the first sampling point V1 at the front end of the first switch unit S1 and the second voltage of the second sampling point V3 at the front end of the main positive relay / pre-charge relay / charging positive relay are collected based on the preset first reference point R1. If the first voltage is greater than the preset first voltage threshold and the second voltage is less than the preset second voltage threshold, then the second sampling point V3 is considered to have an open-circuit fault. For example, if both battery pack 1 and battery pack 2 are 400V, then when the first voltage is greater than 150V and the second voltage is less than 50V, V3 is considered to have an open-circuit fault. At the same time, when the second voltage is greater than 150V, V3 is considered to be normal. After the second switching unit S2 is closed, the first voltage of the fourth sampling point V2 at the rear end of the second switching unit S2 and the second voltage of the second sampling point V3 at the front end of the main positive relay / pre-charge relay / charging positive relay are collected based on the preset first reference point R1. If the first voltage is greater than the preset first voltage threshold and the second voltage is less than the preset second voltage threshold, then the second sampling point V3 is considered to have an open circuit fault. For example, if both battery pack 1 and battery pack 2 are 400V, then if the first voltage is greater than 150V and the second voltage is less than 50V, then V3 is considered to have an open circuit fault. At the same time, if the second voltage is greater than 150V, then V3 is considered to be normal.

[0047] Furthermore, after the pre-charge relay closes, the voltage at the corresponding sampling point is acquired based on the preset first reference point R1, and an open-circuit fault diagnosis is performed on the third sampling point V4 between the main positive relay / pre-charge relay and the load. Specifically, based on the preset first reference point R1, the first voltage of the third sampling point V4 at the rear end of the pre-charge relay / main positive relay and the second voltage of the seventh sampling point V7 at the front end of the load are acquired: if the first voltage is less than the preset second voltage threshold and the second voltage is greater than the preset first voltage threshold, then the third high-voltage sampling point V4 is considered to have an open-circuit fault. For example, if both battery pack 1 and battery pack 2 are 400V, then V4 is considered to have an open-circuit fault when the first voltage is less than 50V and the second voltage is greater than 150V. At the same time, V4 is considered to be normal when the first voltage is greater than 150V.

[0048] After the main positive relay closes, the voltage at the corresponding sampling point is collected based on the preset first reference point R1, and an open-circuit fault diagnosis is performed on the first reference point R1 on the negative terminal of battery pack 1. Specifically, based on the preset first reference point R1, the first voltage of the first sampling point V1 at the front end of the first switching unit S1, the second voltage of the second sampling point V3 at the front end of the main positive relay / pre-charge relay / charging positive relay, and the third voltage of the third sampling point V4 at the rear end of the pre-charge relay / main positive relay are collected. If the first voltage, the second voltage, and the third voltage are all less than the preset second voltage threshold, then an open-circuit fault is considered to have occurred at the first reference point R1. For example, if both battery pack 1 and battery pack 2 are 400V, then an open-circuit fault is considered to have occurred when the first voltage, the second voltage, and the third voltage are all less than 50V. At the same time, R1 is considered normal when the first voltage, the second voltage, and the third voltage are all greater than 150V.

[0049] In addition, it includes collecting the voltage at the corresponding sampling point based on a preset first reference point R1, and performing open-circuit fault diagnosis on the seventh sampling point after fuse 3. Specifically, based on the preset first reference point R1, it collects the first voltage of the third high-voltage sampling point V4 after the pre-charge relay / main positive relay, and the second voltage of the seventh high-voltage sampling point V7 at the front end of the load: if the first voltage is greater than a preset first voltage threshold and the second voltage is less than a preset second voltage threshold, then the seventh high-voltage sampling point V7 is considered to have an open-circuit fault. For example, if both battery pack 1 and battery pack 2 are 400V, then V7 is considered to have an open-circuit fault when the first voltage is greater than 150V and the second voltage is less than 50V. At the same time, V7 is considered to be normal when the second voltage is greater than 150V.

[0050] After both the main positive relay and the main negative relay are closed, the voltage at the corresponding sampling point is collected based on the preset second reference point R2, and an open-circuit fault diagnosis is performed on the second reference point R2 between the main negative relay and the load. Specifically, the first voltage of the first sampling point V1 at the front end of the first switching unit S1 and the second voltage of the third sampling point V4 at the rear end of the pre-charge relay / main positive relay are collected based on the preset second reference point R2. If both the first voltage and the second voltage are less than the preset second voltage threshold, then an open-circuit fault is considered to have occurred at the second reference point R2. For example, if both battery pack 1 and battery pack 2 are 400V, then R2 is considered normal if the first voltage or the second voltage is greater than 150V.

[0051] It should also be noted that when the control command is DC charging, the battery pack 1 and battery pack 2 are controlled to connect in series or parallel for charging based on the output voltage requirement or the input charging voltage. Secondly, the pre-charge relay, main negative relay, and main positive relay must be closed sequentially before the pre-charge relay is opened to ensure high voltage in the high-voltage circuit, meeting the charging requirements. Finally, the charging positive and charging negative relays are closed to initiate DC charging.

[0052] Similarly, after the first switching unit, second switching unit, third switching unit, main positive relay, main negative relay, and pre-charge relay are closed, open-circuit fault diagnosis is performed on the corresponding sampling points and reference points, which will not be detailed here. It should be noted that after the charging positive relay and charging negative relay are closed, the voltage of the corresponding sampling point is collected based on the preset first reference point R1, and open-circuit fault diagnosis is performed on the fifth sampling point V5 between the charging positive relay and the DC charging positive port. Specifically, based on the preset first reference point R1, the first voltage of the fifth sampling point V5 at the rear end of the charging positive relay and the second voltage of the second sampling point V3 at the front end of the main positive relay / pre-charge relay / charging positive relay are collected: if the first voltage is less than the preset second voltage threshold and the second voltage is greater than the preset first voltage threshold, then the fifth sampling point V5 is considered to have an open-circuit fault. For example, if battery pack 1 and battery pack 2 are both 400V, then V5 is considered to have an open-circuit fault when the first voltage is less than 50V and the second voltage is greater than 150V. At the same time, V5 is considered normal when the first voltage is greater than 150V.

[0053] In addition, it includes open-circuit fault diagnosis of the sixth sampling point V6 between the charging negative relay and the DC charging negative port. Specifically, the voltage of the sixth sampling point V6 at the rear end of the charging negative relay is collected based on a preset first reference point R1: if the voltage is less than a preset second voltage threshold, the sixth sampling point V6 is considered to have an open-circuit fault. For example, if both battery pack 1 and battery pack 2 are 400V, then V6 is considered to have an open-circuit fault when the voltage is less than 50V. Meanwhile, V6 is considered normal when the voltage is greater than 150V.

[0054] It can also be understood that when the control command is to lower the high voltage or when AC charging is finished, the main positive relay, the main negative relay, and then the first and third switching units or the second switching unit are disconnected in sequence. When the control command is to finish DC charging, the charging negative relay is disconnected first, then the charging positive relay is disconnected, and finally the main positive relay, the main negative relay, and the first and third switching units or the second switching unit are disconnected accordingly.

[0055] Therefore, after the corresponding switch unit and relay in the vehicle's high-voltage circuit are closed, open-circuit fault diagnosis will be performed on the sampling points on them, which can monitor the working status of the high-voltage circuit in all aspects to maintain its safe and stable reliable operation.

[0056] In summary, this invention provides a control method for a vehicle high-voltage circuit, which can perform comprehensive open-circuit fault diagnosis on the high-voltage circuit after different control commands are executed and the switching unit and relays operate accordingly, thereby maintaining the safe and stable reliable operation of the high-voltage circuit.

[0057] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0058] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A control method for a vehicle high-voltage circuit, characterized in that, The high-voltage circuit includes: a first battery pack and a second battery pack, as well as multiple switching units and multiple relays; wherein, the positive terminal of the first battery pack is connected to the positive terminal of the second battery pack through a first switching unit, and to the negative terminal of the second battery pack through a second switching unit, and the negative terminal of the first battery pack is connected to the negative terminal of the second battery pack through a third switching unit; one end of the main positive relay, the pre-charge relay, and the charging positive relay are all connected to the positive terminal of the second battery pack, the other end of the main positive relay and the pre-charge relay are used to connect to the load, and the other end of the charging positive relay serves as a DC charging positive port; one end of the main negative relay and the charging negative relay are all connected to the negative terminal of the second battery pack, the other end of the main negative relay is used to connect to the load, and the other end of the charging negative relay serves as a DC charging negative port; the control method includes: Obtain control commands from the high-voltage circuit for charging / discharging; The operating states of the drive unit and / or relay are switched according to the control command, so that the first battery pack and the second battery pack can start charging or discharging externally in series / parallel connection. Among them, after the working state of the switching unit and the relay is switched, the voltage of the sampling point on the high voltage circuit is collected based on the preset reference point, and the open circuit fault diagnosis is performed on the sampling point and / or the reference point according to the collected voltage. When the control command is to apply high voltage or AC charging, the first battery pack and the second battery pack are connected in series to charge / discharge or in parallel to charge / discharge through the first switch unit, the second switch unit, and the third switch unit, and the pre-charge relay is closed, the main negative relay is closed, the main positive relay is closed, and then the pre-charge relay is disconnected. Furthermore, after the pre-charge relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the third sampling point between the main positive relay / pre-charge relay and the load based on the voltage. After the main positive relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the first reference point on the negative terminal of the first battery pack based on the voltage. After both the main positive relay and the main negative relay are closed, the voltage at the corresponding sampling point is collected based on the preset second reference point, and an open circuit fault diagnosis is performed on the second reference point between the main negative relay and the load based on the voltage.

2. The control method for the vehicle high-voltage circuit according to claim 1, characterized in that, When the control command is to apply high voltage or to perform AC charging. Based on the output voltage requirement or the input charging voltage, the first and third switching units are controlled to close, and the second switching unit is opened, so that the first battery pack and the second battery pack are connected in parallel for discharge or charging; The precharge relay is closed sequentially, followed by the main negative relay, then the main positive relay, and finally the precharge relay is disconnected. Wherein, after the first switch unit is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the first sampling point between the positive electrode of the first battery pack and the positive electrode of the second battery pack based on the voltage. After both the first switch unit and the third switch unit are closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the second sampling point between the second battery pack and the main positive relay / pre-charge relay / charging positive relay based on the voltage. After the precharge relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the third sampling point between the main positive relay / precharge relay and the load based on the voltage. After the main positive relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the first reference point on the negative terminal of the first battery pack based on the voltage. After both the main positive relay and the main negative relay are closed, the voltage at the corresponding sampling point is collected based on the preset second reference point, and an open circuit fault diagnosis is performed on the second reference point between the main negative relay and the load based on the voltage.

3. The control method for the vehicle high-voltage circuit according to claim 1, characterized in that, When the control command is to apply high voltage or AC charging. Based on the output voltage requirement or the input charging voltage, the second switching unit is controlled to close, while the first and third switching units are opened, so that the first battery pack and the second battery pack are connected in series for discharge or charging; The pre-charge relay is closed sequentially, followed by the main negative relay, then the main positive relay, and finally the pre-charge relay is disconnected. Specifically, after the second switch unit is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the fourth sampling point between the positive terminal of the first battery pack and the negative terminal of the second battery pack based on the voltage, and the open circuit fault diagnosis is performed on the second sampling point between the second battery pack and the main positive relay / pre-charge relay / charging positive relay. After the precharge relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the third sampling point between the main positive relay / precharge relay and the load based on the voltage. After the main positive relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the first reference point on the negative terminal of the first battery pack based on the voltage. After both the main positive relay and the main negative relay are closed, the voltage at the corresponding sampling point is collected based on the preset second reference point, and an open circuit fault diagnosis is performed on the second reference point between the main negative relay and the load based on the voltage.

4. The control method for the vehicle high-voltage circuit according to claim 1, characterized in that, When the control command is DC charging Based on the output voltage requirement or the input charging voltage, the first and third switching units are controlled to close, and the second switching unit is opened, so that the first battery pack and the second battery pack are charged in parallel; The system sequentially controls the pre-charge relay to close, the main negative relay to close, the main positive relay to close, and then disconnects the pre-charge relay, and closes the charging positive relay and the charging negative relay. Wherein, after the first switch unit is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the first sampling point between the positive electrode of the first battery pack and the positive electrode of the second battery pack based on the voltage. After both the first switch unit and the third switch unit are closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the second sampling point between the second battery pack and the main positive relay / pre-charge relay / charging positive relay based on the voltage. After the precharge relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the third sampling point between the main positive relay / precharge relay and the load based on the voltage. After the main positive relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the first reference point on the negative terminal of the first battery pack based on the voltage. After both the main positive relay and the main negative relay are closed, the voltage at the corresponding sampling point is collected based on the preset second reference point, and an open circuit fault diagnosis is performed on the second reference point between the main negative relay and the load based on the voltage. After the positive charging relay and the negative charging relay are closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the fifth sampling point between the positive charging relay and the DC charging positive port based on the voltage, and the open circuit fault diagnosis is performed on the sixth sampling point between the negative charging relay and the DC charging negative port.

5. The control method for the vehicle high-voltage circuit according to claim 1, characterized in that, When the control command is DC charging Based on the output voltage requirement or the input charging voltage, the second switching unit is controlled to close, while the first and third switching units are opened, so that the first battery pack and the second battery pack are charged in series. The system sequentially controls the pre-charge relay to close, the main negative relay to close, the main positive relay to close, then disconnects the pre-charge relay, and then closes the charging positive relay and the charging negative relay. Specifically, after the second switch unit is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the fourth sampling point between the positive terminal of the first battery pack and the negative terminal of the second battery pack based on the voltage, and the open circuit fault diagnosis is performed on the second sampling point between the second battery pack and the main positive relay / pre-charge relay / charging positive relay. After the precharge relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the third sampling point between the main positive relay / precharge relay and the load based on the voltage. After the main positive relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the first reference point on the negative terminal of the first battery pack based on the voltage. After both the main positive relay and the main negative relay are closed, the voltage at the corresponding sampling point is collected based on the preset second reference point, and an open circuit fault diagnosis is performed on the second reference point between the main negative relay and the load based on the voltage. After the positive charging relay and the negative charging relay are closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the fifth sampling point between the positive charging relay and the DC charging positive port based on the voltage, and the open circuit fault diagnosis is performed on the sixth sampling point between the negative charging relay and the DC charging negative port.

6. The control method for the vehicle high-voltage circuit according to claim 1, characterized in that, The high-voltage circuit also includes a fuse, which is connected in series between the main positive relay and the load.

7. The control method for the vehicle high-voltage circuit according to claim 6, characterized in that, After the main positive relay is closed, the voltage of the corresponding sampling point is collected based on the preset first reference point, and the open circuit fault diagnosis is performed on the seventh sampling point at the back end of the fuse based on the voltage.

8. The control method for the vehicle high-voltage circuit according to claim 7, characterized in that, The open-circuit fault diagnosis steps for the seventh sampling point include: The first voltage at the third sampling point at the rear end of the precharge relay / main positive relay and the second voltage at the seventh sampling point at the front end of the load are acquired based on the preset first reference point: If the first voltage is greater than a preset first voltage threshold and the second voltage is less than a preset second voltage threshold, then the seventh sampling point is considered to have an open circuit fault.

9. The control method for the vehicle high-voltage circuit according to claim 2 or 4, characterized in that, The open-circuit fault diagnosis steps for the first sampling point include: The first voltage at the first sampling point at the front end of the first switching unit is acquired based on a preset first reference point, and the second voltage at the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay is acquired, and the difference between them is calculated: If the difference is greater than a preset second voltage threshold and the first voltage is less than the preset second voltage threshold, then the first sampling point is considered to have an open circuit fault.

10. The control method for a vehicle high-voltage circuit according to claim 3 or 5, characterized in that, The open-circuit fault diagnosis steps for the fourth sampling point include: The first voltage at the fourth sampling point at the rear end of the second switching unit and the second voltage at the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay are collected based on a preset first reference point. If the first voltage is less than a preset second voltage threshold and the second voltage is greater than a preset third voltage threshold, then the fourth sampling point is considered to have an open circuit fault.

11. The control method for the vehicle high-voltage circuit according to claim 2 or 4, characterized in that, The open-circuit fault diagnosis steps for the second sampling point include: The first voltage at the fourth sampling point at the rear end of the second switching unit and the second voltage at the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay are collected based on a preset first reference point. If the first voltage is greater than a preset first voltage threshold and the second voltage is less than a preset second voltage threshold, then the second sampling point is considered to have an open circuit fault.

12. The control method for the vehicle high-voltage circuit according to claim 3 or 5, characterized in that, The open-circuit fault diagnosis steps for the second sampling point include: The first voltage at the first sampling point at the front end of the first switching unit and the second voltage at the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay are collected based on a preset first reference point. If the first voltage is greater than a preset first voltage threshold and the second voltage is less than a preset second voltage threshold, then the second sampling point is considered to have an open circuit fault.

13. The control method for a vehicle high-voltage circuit according to any one of claims 2 to 5, characterized in that, The open-circuit fault diagnosis steps for the third sampling point include: The first voltage at the third sampling point at the rear end of the precharge relay / main positive relay and the second voltage at the seventh sampling point at the front end of the load are acquired based on a preset first reference point: If the first voltage is less than a preset second voltage threshold and the second voltage is greater than a preset first voltage threshold, then the third sampling point is considered to have an open circuit fault.

14. The control method for a vehicle high-voltage circuit according to any one of claims 2 to 5, characterized in that, The open-circuit fault diagnosis steps for the first reference point include: The first voltage at the first sampling point at the front end of the first switching unit, the second voltage at the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay, and the third voltage at the third sampling point at the rear end of the pre-charge relay / main positive relay are collected based on a preset first reference point. If the first voltage, the second voltage, and the third voltage are all less than a preset second voltage threshold, then the first reference point is considered to have an open circuit fault.

15. The control method for a vehicle high-voltage circuit according to any one of claims 2 to 5, characterized in that, The open-circuit fault diagnosis steps for the second reference point include: The first voltage at the first sampling point at the front end of the first switching unit and the second voltage at the third sampling point at the rear end of the precharge relay / main positive relay are collected based on a preset second reference point. If both the first voltage and the second voltage are less than a preset second voltage threshold, then the second reference point is considered to have an open circuit fault.

16. The control method for a vehicle high-voltage circuit according to claim 4 or 5, characterized in that, The open-circuit fault diagnosis steps for the fifth sampling point include: The first voltage at the fifth sampling point at the rear end of the charging positive relay and the second voltage at the second sampling point at the front end of the main positive relay / pre-charge relay / charging positive relay are collected based on a preset first reference point. If the first voltage is less than a preset second voltage threshold and the second voltage is greater than a preset first voltage threshold, then the fifth sampling point is considered to have an open circuit fault.

17. The control method for a vehicle high-voltage circuit according to claim 4 or 5, characterized in that, The open-circuit fault diagnosis steps for the sixth sampling point include: The voltage at the sixth sampling point at the rear end of the charging negative relay is acquired based on a preset first reference point: If the voltage is less than the preset second voltage threshold, then the sixth sampling point is considered to have an open circuit fault.

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