Method and system for detecting adhesion of high-voltage relay of new energy automobile

Abstract

The invention discloses a high-voltage relay adhesion detection method and system for a new energy automobile, and belongs to the field of new energy automobiles. The power battery output circuit comprises a power battery positive electrode, a main positive relay, a load, a main negative relay and a power battery negative electrode which are sequentially connected in series, and a whole formed by connecting a pre-charging resistor and a pre-charging relay in series is connected to the two ends of the main positive relay in parallel. According to the method, the voltage at the two ends of the power battery and the voltage at the input end of the load are obtained through the battery management system and compared, and meanwhile adhesion detection of the high-voltage relay is conducted by combining action control over the main positive relay, the main negative relay and the pre-charging relay. Compared with the traditional technology, the method is safer, more efficient and lower in cost.

Description

Technical Field

[0001] The present invention belongs to the field of new energy vehicles, and in particular, relates to a method and system for detecting adhesion of a high-voltage relay of a new energy vehicle. Background Art

[0002] With the rapid development of the new energy vehicle industry, the safety and reliability of high-voltage electrical systems have become the focus of the industry. During the high-voltage power-on process, the adhesion problem of high-voltage relays may cause serious safety hazards and affect the safety of vehicles and personnel.

[0003] The comparative document (CN117825940A) provides a contactor adhesion detection circuit and detection method thereof, a high-voltage power distribution circuit and a vehicle, wherein the adhesion detection circuit includes a battery voltage sampling unit, a bus voltage sampling unit, a front-end voltage sampling unit, a rear-end voltage sampling unit and a processing unit; the processing unit can refer to the battery voltage Vbat collected by the battery voltage sampling unit, the bus voltage Vbus collected by the bus voltage sampling unit, the front-end voltage Vq collected by the front-end voltage sampling unit and the rear-end voltage Vh collected by the rear-end voltage sampling unit, to detect the adhesion of the main negative contactor and / or the distribution contactor, thereby improving the safety of traffic power. Moreover, the adhesion detection circuit provided by the present invention realizes adhesion detection only through a few simple voltage sampling units, namely, a battery voltage sampling unit, a bus voltage sampling unit, a front-end voltage sampling unit and a rear-end voltage sampling unit, so that the structure of the adhesion detection circuit is simpler and the cost is lower.

[0004] However, the above-mentioned reference documents, like the traditional high-voltage relay adhesion detection method, rely on the multi-channel high-voltage detection circuit integrated in the battery management system to obtain the voltage across the main positive relay or the main negative relay, which not only increases the complexity of the system, but also significantly increases the cost. Therefore, it is particularly important to develop a safer, more efficient and lower-cost adhesion detection method. Summary of the invention

[0005] The present invention aims to overcome the shortcomings of the prior art and proposes a high-voltage relay adhesion detection method and system for new energy vehicles to achieve the following objectives: by obtaining the voltage across the power battery and the voltage at the load input terminal, combined with the precise control of the main positive, main negative and pre-charge relay action sequence, the adhesion detection of the high-voltage relay is realized, thereby simplifying the high-voltage detection circuit of the battery management system, reducing the unit cost, and improving the safety and stability of the system. .

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for detecting adhesion of a high-voltage relay of a new energy vehicle, wherein a power battery output circuit comprises a power battery positive electrode, a main positive relay, a load, a main negative relay, and a power battery negative electrode connected in series in sequence, wherein a pre-charging resistor and a pre-charging relay are connected in series as a whole and connected in parallel at both ends of the main positive relay. The method obtains and compares the voltage at both ends of the power battery and the voltage at the input end of the load through a battery management system, and simultaneously performs high-voltage relay adhesion detection in combination with the action control of the main positive relay, the main negative relay, and the pre-charging relay.

[0008] Preferably, the voltage across the power battery is directly sampled by the battery management system.

[0009] Preferably, the load is provided with a voltage sampling unit, and the voltage sampling unit is used to sample the voltage at the load input terminal, and the battery management system communicates with the load via CAN to obtain the voltage at the load input terminal.

[0010] Preferably, the load includes a motor controller, an on-board charger, and a DC / DC converter.

[0011] Preferably, the method comprises:

[0012] After receiving the high-voltage power-on command, the battery management system obtains and compares the voltage Ub at both ends of the power battery and the voltage Um at the load input end without closing any relay;

[0013] If Um>n*Ub, where n is the preset proportional coefficient, it means that the main positive relay and the main negative relay are simultaneously adhered; otherwise, only the pre-charge relay is closed, and after the preset first delay time, the Um voltage is obtained and then compared;

[0014] If Um>n*Ub is satisfied at this time, it means that the main negative relay is stuck; otherwise, disconnect the pre-charge relay, close the main negative relay, obtain the Um voltage at this time and then compare;

[0015] If Um>n*Ub is satisfied at this time, it means that the main positive relay or the pre-charging relay is stuck; otherwise, the pre-charging relay is closed, and the main positive relay is closed after Um>n*Ub, and then the pre-charging relay is disconnected after the second delay time to complete the pre-charging;

[0016] Finally, the battery management system completes high voltage power-up and adhesion detection.

[0017] Preferably, the proportionality coefficient n is 95%.

[0018] Preferably, when the relay sticks, the battery management system controls the power battery to be powered off and sends a fault signal to the instrument, and the instrument reminds the user according to the fault signal.

[0019] Preferably, the first delay time is 500ms.

[0020] Preferably, the second delay time is 50ms.

[0021] At the same time, the present application also proposes a high-voltage relay adhesion detection system for new energy vehicles, the system including a power battery output circuit and a battery management system, wherein the battery management system is communicatively connected to the load in the power battery output circuit, and the battery management system is used to execute a program constructed according to the above-mentioned high-voltage relay adhesion detection method for new energy vehicles.

[0022] The technical effects of the present invention are:

[0023] (1) This application realizes adhesion detection of high-voltage relays by obtaining the voltage across the power battery and the voltage at the load input terminal, combined with precise control of the action sequence of the main positive, main negative and pre-charge relays, thereby simplifying the high-voltage detection circuit of the battery management system, reducing the unit cost, and improving the safety and stability of the system.

[0024] (2) The present application can share the high-voltage sampling function of the load, so that the battery management system does not need to design a complex multi-channel high-voltage detection circuit, which greatly reduces the hardware investment cost of the battery management system.

[0025] (3) The battery management system hardware circuit of the present application is simple and reliable, and supports communication with the load to obtain the load input voltage. Different from the prior art which is limited by the number of BMS high-voltage detection circuits, the voltage detection method of the present application is efficient and low-cost, and can realize adhesion detection of all relays. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a power battery output circuit diagram of an embodiment of the present invention;

[0027] Figure 2 This is a flow chart of a method for detecting adhesion of a high-voltage relay of a new energy vehicle according to an embodiment of the present invention;

[0028] Figure 1 In the middle: 1 is the power battery; 2 is the main negative relay; 3 is the main positive relay; 4 is the pre-charge relay; 5 is the pre-charge resistor. DETAILED DESCRIPTION

[0029] The following is a further detailed description of the specific implementation of the present invention through the description of the embodiments with reference to the accompanying drawings, with the purpose of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation. It should be noted that the words "first", "second" and the like described in this application are only for the convenience of describing the technical solution to distinguish different components, modules, ingredients, data, etc., and are not used to limit this application. In order to make the technical solution of the present invention clearer, the present invention is explained by the following embodiments.

[0030] In the related technology of new energy vehicles, the output circuit of the power battery (battry) is often configured with a main positive relay and a main negative relay to control the output of the power battery, and to cut off the circuit in time when either the power battery or the load fails, thereby protecting the circuit safety between the power battery and the load. With the development of new energy technology and higher circuit safety requirements, in the current power battery output circuit, a pre-charge relay and a pre-charge resistor are configured to charge the load capacitor (pre-charge capacitor) to reduce spark arcing when the relay is closed, reduce impact, increase safety, and avoid adhesion damage caused by overcurrent and overheating of the relay. Among them, the main positive relay, the main negative relay, and the pre-charge relay are all uniformly controlled by the battery management system (BMS), but with the increase of service life, the relay will inevitably still have adhesion damage, which brings safety hazards to the power battery output circuit.

[0031] Specifically, the power battery output circuit of this embodiment is as follows: Figure 1 As shown, it includes the negative electrode of the power battery 1, the main negative relay 2, the load, the main positive relay 3, and the positive electrode of the power battery 1 connected in series in sequence. At the same time, the power battery output circuit also includes a pre-charge relay 4 and a pre-charge resistor 5, and the pre-charge relay 4 and the pre-charge resistor 5 are connected in series as a whole in parallel at both ends of the main positive relay 3. Similarly, the main negative relay 2, the main positive relay 3, and the pre-charge relay 4 are all controlled by the battery management system. Among them, the voltage across the power battery is represented as Ub, and the voltage at the load input end is represented as Um.

[0032] Based on the above-mentioned power battery output circuit, this embodiment proposes a high-voltage relay adhesion detection method for new energy vehicles. The relay adhesion detection method in the prior art mainly relies on the multi-channel high-voltage detection circuit integrated in the battery management system for voltage detection. However, when the high-voltage detection circuit of the battery management system is insufficient, it is impossible to realize adhesion detection of some relays. Therefore, different from the prior art, this embodiment only needs to obtain the voltage across the power battery and the voltage at the load input terminal, and then, combined with the precise control of the action sequence of the main negative relay 2, the main positive relay 3, and the pre-charge relay 4, the adhesion detection of the high-voltage relay is realized, thereby simplifying the high-voltage detection circuit of the battery management system, reducing the unit cost, and improving the safety and stability of the system.

[0033] Specifically, the battery management system is an electronic system for monitoring and managing the performance of the battery pack. Its main functions include monitoring the status of the battery, protecting the battery safety, optimizing the battery performance and extending the service life of the battery. It has become the norm to equip the power battery of new energy vehicles with a battery management system. Therefore, the voltage across the power battery of this embodiment can be directly sampled and obtained by the battery management system, which is efficient and reliable. Among them, if the power battery is a battery pack composed of multiple power battery cells connected in series, the total voltage value after the power battery cell voltages are accumulated is used as the voltage across the power battery. Similarly, if multiple power battery cells are connected in parallel or mixed (series-parallel mixed) to form a battery pack, the total voltage after the cell voltages are connected in parallel or mixed (series-parallel mixed) is used as the voltage across the power battery.

[0034] For the voltage across the load, traditional technology often relies on the battery management system to add a high-voltage detection circuit to detect the voltage at the load input terminal. However, the loads of existing new energy vehicles are highly integrated and have various functions. For example, the motor controller (MCU), the on-board charger (OBC), the DC / DC converter, etc. are all equipped with a voltage sampling unit, which is used to sample the voltage at the load input terminal. If another high-voltage detection circuit is added, repeated sampling of the load input terminal voltage will result, resulting in a waste of resources, increased hardware costs and system complexity. Therefore, in this embodiment, the battery management system is configured to communicate with the load through CAN, so that the load input terminal voltage can be directly read from the load, which is more efficient, more accurate and significantly reduces costs. The battery management system of the present application does not require a complex multi-channel high-voltage detection circuit, the hardware circuit is simple and reliable, and supports communication with the load to obtain the load input terminal voltage. Different from the prior art, which is limited by the number of BMS high-voltage detection circuits, the voltage detection method of the present application is efficient and low-cost, and can achieve adhesion detection of all relays.

[0035] At the same time, in order to further improve the accuracy of load input voltage sampling, the battery management system can communicate with multiple loads at the same time. In this case, the load input voltage values ​​read from multiple loads form redundant backup and verification with each other, so that obviously abnormal data can be eliminated. At the same time, combined with conventional data processing methods such as average method, filter filtering, data fusion, etc., the reliability and accuracy of the load input voltage sampling data can be effectively improved.

[0036] In this embodiment, the load is the motor controller MCU, and the MCU is connected to the battery management system via the CAN bus (in specific implementation, other buses can also be used according to actual conditions). The CAN bus is a communication protocol widely used in the fields of automobiles and industrial automation. It has stable data transmission, fast data transmission speed, low deployment cost, and flexible network topology, that is, it supports communication between multiple electronic control units, and retains the possibility of communication between the battery management system and other electronic control units. In short, this embodiment shares the high-voltage sampling function of the motor controller MCU, so that the battery management system does not need to design a complex multi-channel high-voltage detection circuit, which greatly reduces the hardware investment cost of the battery management system.

[0037] like Figure 2 As shown in the method flow chart, a high-voltage relay adhesion detection method proposed in this embodiment specifically includes:

[0038] After the new energy vehicle power-on initialization (including vehicle hardware self-test, software parameter initialization, etc.) is completed, the battery management system receives the high-voltage power-on command and starts high-voltage relay adhesion detection;

[0039] First, without closing any relay, that is, all relays remain open, the battery management system obtains the voltage Ub across the power battery and the voltage Um at the load input terminal and compares them;

[0040] If the battery management system determines that Um>n*Ub, where n is a preset proportional coefficient (preset to 95% in this embodiment, the same below, and can be flexibly set according to actual conditions during specific implementation), it means that the main positive relay and the main negative relay are simultaneously stuck. At this time, the battery management system controls the power battery to power off and sends a fault signal to the instrument, and the instrument reminds the user according to the fault signal; if the battery management system determines that Um≤n*Ub, only the pre-charge relay is closed, and after a preset first delay time (preset to 500ms in this embodiment, and can be flexibly set according to actual conditions during specific implementation), the Um voltage is obtained for comparison;

[0041] If the battery management system determines that Um>n*Ub at this time, it means that the main negative relay is stuck. At this time, the battery management system controls the power battery to power off and sends a fault signal to the instrument. The instrument reminds the user according to the fault signal; if the battery management system determines that Um≤n*Ub at this time, the pre-charge relay is disconnected, the main negative relay is closed, and the Um voltage at this time is obtained for comparison;

[0042] If the battery management system determines that Um>n*Ub at this time, it means that the main positive relay or the pre-charging relay is stuck. At this time, the battery management system controls the power battery to power off and sends a fault signal to the instrument. The instrument reminds the user according to the fault signal; if the battery management system determines that Um≤n*Ub at this time, it means that all relays are normal, and the power battery output circuit can start pre-charging, that is, close the pre-charging relay, and close the main positive relay after Um>n*Ub, and then disconnect the pre-charging relay after the second delay time (preset to 50ms in this embodiment, and can be flexibly set according to actual conditions during specific implementation), thereby completing the pre-charging; finally, the battery management system completes high-voltage power-on and adhesion detection.

[0043] At the same time, this embodiment also proposes a high-voltage relay adhesion detection system for new energy vehicles, the system including a power battery output circuit and a battery management system, wherein the battery management system is communicatively connected to the load in the power battery output circuit, and is used to execute a program constructed according to the above-mentioned high-voltage relay adhesion detection method for new energy vehicles.

[0044] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for detecting adhesion of a high-voltage relay of a new energy vehicle, wherein the power battery output circuit comprises a power battery positive electrode, a main positive relay, a load, a main negative relay, a power battery negative electrode, which are connected in series in sequence. The pre-charging resistor and the pre-charging relay are connected in series and connected in parallel at both ends of the main positive relay. The method is characterized in that: the method obtains the voltage at both ends of the power battery and the voltage at the load input end through a battery management system and compares them, and at the same time combines the action control of the main positive relay, the main negative relay, and the pre-charging relay to perform high-voltage relay adhesion detection.

2. A method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 1, characterized in that: The voltage across the power battery is directly sampled by the battery management system.

3. The method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 1, characterized in that: The load is provided with a voltage sampling unit, and the voltage sampling unit is used to sample the voltage at the load input terminal. The battery management system communicates with the load via CAN to obtain the voltage at the load input terminal.

4. The method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 3, characterized in that: The load includes a motor controller, an on-board charger, and a DC / DC converter.

5. The method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 1, characterized in that: The method comprises: After receiving the high-voltage power-on command, the battery management system obtains and compares the voltage Ub at both ends of the power battery and the voltage Um at the load input end without closing any relay; If Um>n*Ub, where n is the preset proportional coefficient, it means that the main positive relay and the main negative relay are simultaneously adhered; otherwise, only the pre-charge relay is closed, and after the preset first delay time, the Um voltage is obtained and then compared; If Um>n*Ub is satisfied at this time, it means that the main negative relay is stuck; otherwise, disconnect the pre-charge relay, close the main negative relay, obtain the Um voltage at this time and then compare; If Um>n*Ub is satisfied at this time, it means that the main positive relay or the pre-charging relay is stuck; otherwise, the pre-charging relay is closed, and the main positive relay is closed after Um>n*Ub, and then the pre-charging relay is disconnected after the second delay time to complete the pre-charging; Finally, the battery management system completes high voltage power-up and adhesion detection.

6. The method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 5, characterized in that: The proportionality coefficient n is set to 95%.

7. The method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 5, characterized in that: When the relay sticks, the battery management system controls the power battery to be powered off and sends a fault signal to the instrument, and the instrument reminds the user according to the fault signal.

8. The method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 5, characterized in that: The first delay time is 500ms.

9. The method for detecting adhesion of a high-voltage relay of a new energy vehicle according to claim 5, characterized in that: The second delay time is 50ms.

10. A high-voltage relay adhesion detection system for new energy vehicles, characterized in that: The system includes a power battery output circuit and a battery management system, wherein the battery management system is communicatively connected to a load in the power battery output circuit, and the battery management system is used to execute a program constructed according to a high-voltage relay adhesion detection method for a new energy vehicle according to any one of claims 1-9.

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