An electric vehicle insulation resistance simulation circuit

Abstract

The utility model relates to electric automobile battery management system (BMS) test technical field discloses an electric automobile insulation resistance simulation circuit. The electric automobile insulation resistance simulation circuit includes communication module, control module and two way same connection to control module's insulation resistance simulation execution circuit, and each insulation resistance simulation execution circuit contains relay drive module and resistance array and relay module. The communication module transmits to control module generation control signal after receiving the instruction that host computer sends, and the control signal is driven to enhance through relay drive module, makes the relay in resistance array and relay module reliably attract and disconnect, to meet the test demand of BMS to different insulation resistance resistance value.

Description

Technical Field

[0001] This utility model relates to the technical field of testing electric vehicle battery management systems, and in particular to a simulation circuit for the insulation resistance of electric vehicles. Background Technology

[0002] The high-voltage system of an electric vehicle (voltage typically covers 300V-1000V) is the core of the vehicle's power output. The battery management system (BMS), as the "nerve center" of the high-voltage system, not only undertakes basic functions such as battery status monitoring (SOC, SOH) and charge and discharge control, but also needs to monitor the insulation resistance value between the high-voltage system and the vehicle chassis in real time. This is a key line of defense to prevent high-voltage leakage, ensure the safety of passengers and the stable operation of the vehicle's electrical system.

[0003] However, BMS development, factory testing, and maintenance calibration cannot rely on actual vehicle high-voltage system testing: firstly, actual vehicle testing is costly and complex, and insulation resistance is affected by factors such as aging, temperature, and humidity, making it difficult to stably reproduce different insulation states; secondly, actual vehicles cannot accurately control the insulation resistance value, resulting in the inability to fully verify the insulation monitoring function of the BMS. Utility Model Content

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, the invention provides an electric vehicle insulation resistance simulation circuit that can simulate the insulation resistance between the positive and negative terminals of the high-voltage system and the vehicle ground (outer casing ground). This allows engineers to set insulation parameters with different resistance values ​​to test the BMS's processing, diagnosis, and alarm functions for different resistance values, thereby improving testing efficiency.

[0005] The objective of this utility model can be achieved through the following technical solution: an electric vehicle insulation resistance simulation circuit, including a communication module, a control module, and two identical insulation resistance simulation execution circuits connected to the control module, wherein the control module is also connected to the communication module.

[0006] As one possible implementation, the communication module of the electric vehicle insulation resistance simulation circuit includes a CAN bus, which receives instructions from an external host computer and then transmits the instructions to the control module. The control module includes an MCU (microcontroller), which parses the instructions received from the CAN bus and generates control signals for the insulation resistance simulation execution circuit.

[0007] Furthermore, the insulation resistance simulation execution circuit includes a resistor array and relay module and a relay drive module. The resistor array and relay module includes several resistors connected in series in the main circuit and relays connected in parallel with the corresponding resistors. The relay drive module receives the control signal output by the MCU and then drives and enhances the control signal so that the relays can reliably engage and disengage, thereby realizing the dynamic simulation of different insulation resistances.

[0008] Furthermore, the resistor array and relay module includes an overcurrent protection module, which comprises a main circuit relay, a sampling resistor, a current-limiting resistor, a pull-up resistor, an optocoupler, and an overcurrent protection module interface. The sampling resistor is connected to the main circuit relay in series in the main circuit. The current-limiting resistor is connected to the optocoupler, and simultaneously, the current-limiting resistor and the optocoupler are connected in parallel across the sampling resistor. The pull-up resistor is connected to both the optocoupler and the overcurrent protection module interface. The overcurrent protection module interface is connected to the MCU.

[0009] The sampling resistor is a high-precision resistor. When current flows through the main circuit, a voltage difference will be generated across the sampling resistor according to Ohm's law, and this voltage difference is directly applied to the optocoupler. When the main circuit current exceeds the protection threshold, i.e., the voltage across the sampling resistor is high enough, the optocoupler conducts. After the optocoupler conducts, the optocoupler level switches from the high level of the pull-up resistor to the low level. The overcurrent protection module interface outputs a low level, and then outputs an overcurrent fault signal to the MCU through the overcurrent protection module interface. Upon receiving the fault signal, the MCU immediately controls the main circuit relay to disconnect the main circuit, thereby cutting off the current and realizing overcurrent protection.

[0010] In addition, the current-limiting resistor is connected to the optocoupler, providing a bypass path that can divert small interference currents to prevent false triggering. It can also limit the peak current flowing through the optocoupler, thus providing protection.

[0011] The resistance output terminals (positive and negative) of the electric vehicle insulation resistance simulation circuit described in this invention are directly connected to the high-voltage sampling interface of the BMS, serving as an insulation resistance generator. This allows for precise control of the insulation resistance value, facilitating the testing of the BMS's insulation monitoring function. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the structure of an electric vehicle insulation resistance simulation circuit according to some embodiments of the present invention.

[0014] Figure 2 This is a schematic diagram of a single-channel electric vehicle insulation resistance simulation circuit according to some embodiments of the present invention.

[0015] Figure 3 This is another structural schematic diagram of a single-channel electric vehicle insulation resistance simulation circuit according to some embodiments of this utility model.

[0016] Explanation of reference numerals in the attached figures

[0017] 100—Electric vehicle insulation resistance simulation circuit, 10—Communication module, 20—Control module, 30—Insulation resistance simulation execution circuit 1, 40—Insulation resistance simulation execution circuit 2, 31—Relay drive module, 32—Resistor array and relay, 32-1—Overcurrent protection module, R1~R20—High-precision fixed resistors, K1~K20—Control relays corresponding to R1~R20, K21—Main circuit relay, R21—Sampling resistor, R22—Current limiting resistor, R23—Pull-up resistor, U1—Optocoupler, CH+—Positive terminal of resistor output, CH-—Negative terminal of resistor output, IM2—Overcurrent protection module interface, GND—Ground. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0019] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this utility model should have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar words used in the embodiments of this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] The specific solution of the electric vehicle insulation resistance simulation circuit provided by this utility model is described in detail below with reference to the accompanying drawings.

[0021] Please see Figure 1 An embodiment of the present invention provides an electric vehicle insulation resistance simulation circuit 100, which includes a communication module 10, a control module 20, an insulation resistance simulation execution circuit 1 (30) and an insulation resistance simulation execution circuit 2 (40). The control module 20 is connected to the communication module 10, the insulation resistance simulation execution circuit 1 (30) and the insulation resistance simulation execution circuit 2 (40) respectively, and the insulation resistance simulation execution circuit 1 (30) and the insulation resistance simulation execution circuit 2 (40) are the same circuit.

[0022] Further, please refer to Figure 2 A schematic diagram of a single-channel structure of an electric vehicle insulation resistance simulation circuit 100 provided in one embodiment of the present invention is shown. The insulation resistance simulation execution circuit 1 (30) includes a relay drive module 31 and a resistor array and relay module 32. The relay drive module 31 is connected to the control module 20, and the resistor array and relay module 32 is connected to the relay drive module 31.

[0023] Furthermore, please refer to Figure 3 In this embodiment of the invention, the control module 20 of the electric vehicle insulation resistance simulation circuit 100 includes a CAN bus and a microcontroller (MCU). The resistor array and relay module 32 includes high-precision custom resistors R1~R20 connected in series in the main circuit and relays K1~K20 connected in parallel with the corresponding resistors R1~R20. The communication module 10 (CAN) receives instructions from an external host computer and then transmits the instructions to the control module 20 (MCU). The MCU parses the instructions received from the CAN bus and generates control signals for the insulation resistance simulation execution circuit 30. The relay drive module 31 then receives the control signals output by the MCU and amplifies the control signals, enabling the relays to reliably engage and disengage, thereby achieving dynamic simulation of different insulation resistances.

[0024] In this embodiment of the invention, resistor R1 has a resistance of 100Ω, resistor R2 has a resistance of 200Ω, resistor R3 has a resistance of 400Ω, ..., resistor R20 has a resistance of 52428.8kΩ, and the power supply is a 12V DC power supply. It can simulate a resistance range of 100Ω to 100 MΩ, in 100Ω increments, to meet the testing requirements of BMS for different insulation resistances.

[0025] Furthermore, the insulation resistance simulation execution circuit 1 (30) also includes an overcurrent protection module 32-1. The overcurrent protection module 32-1 includes a main circuit relay K21, a sampling resistor R21, a current-limiting resistor R22, a pull-up resistor R23, an optocoupler U1, and an overcurrent protection module interface IM2. The sampling resistor R21 (with a resistance of 100Ω) is connected to the main circuit relay K21 in series in the main circuit; the current-limiting resistor R22 is connected to the optocoupler U1, and at the same time, the current-limiting resistor R22 and the optocoupler U1 are connected in parallel with the sampling resistor R21; the pull-up resistor R23 is connected to both the optocoupler U1 and the overcurrent protection module interface IM2; the overcurrent protection module interface IM2 is connected to the MCU.

[0026] In this embodiment of the invention, the maximum allowable current through each main circuit channel is 10mA. When the current exceeds 10mA, optocoupler U1 conducts, and the voltage level of optocoupler U1 switches from high to low due to the pull-up resistor R23 (5.1kΩ). At this time, the overcurrent protection module interface IM2 outputs a low level, and then outputs an overcurrent fault signal to the MCU through the overcurrent protection module interface IM2. Upon receiving the fault signal, the MCU immediately controls the main circuit relay K21 to disconnect the main circuit, thereby cutting off the current and achieving overcurrent protection. In addition, the current-limiting resistor R22 (22Ω) is connected to optocoupler U1, providing a bypass path to divert small interference currents and prevent false triggering. It also limits the peak current flowing through optocoupler U1, thus providing protection.

[0027] In summary, the electric vehicle insulation resistance simulation circuit proposed in this utility model has a simple circuit structure. As a resistance generator, it can simulate a wide range of resistances, accurately control the insulation resistance value, facilitate insulation monitoring testing, save BMS testing costs, and improve testing efficiency.

[0028] Furthermore, although the circuit structure features of this invention are described in a specific combination in the accompanying drawings, this does not require or imply that the structure of this invention must be constructed in that combination, or that all the modules shown must be applied to achieve the desired result.

[0029] While the spirit and principles of this invention have been described with reference to several specific embodiments, it should be understood that this invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that features in these aspects cannot be combined for benefit; such division is merely for ease of description. This invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the appended claims is to be interpreted in the broadest sense, thereby encompassing all such modifications and equivalent structures and functions.

Claims

1. A simulation circuit for the insulation resistance of an electric vehicle, characterized in that, It includes a communication module, a control module, and two identical insulation resistance simulation execution circuits connected to the control module; wherein the control module is connected to the communication module.

2. The electric vehicle insulation resistance simulation circuit according to claim 1, characterized in that, The communication module includes CAN, which receives instructions sent by an external host computer and transmits them to the control module; The control module includes an MCU (microcontroller) that parses the instructions received from the CAN bus and generates control signals. The insulation resistance simulation execution circuit includes a relay drive module and a resistor array and relay module; the resistor array and relay module includes several high-precision custom resistors connected in series in the main circuit and relays connected in parallel to the corresponding high-precision custom resistors, and the resistor array and relay module is connected to the relay drive module. The relay driving module is connected to the MCU. The relay driving module receives the control signal output by the MCU and then drives and enhances the control signal to reliably engage and disengage the relays corresponding to the resistor array in the relay module, thereby realizing the dynamic simulation of different insulation resistances.

3. The electric vehicle insulation resistance simulation circuit according to claim 2, characterized in that, The resistor array and relay module also includes an overcurrent protection module, which includes a main relay, a sampling resistor, a current limiting resistor, a pull-up resistor, an optocoupler, and an overcurrent protection module interface. The sampling resistor is connected in series with the main circuit relay on the main circuit; the current limiting resistor is connected in parallel with the optocoupler and the sampling resistor; the pull-up resistor is connected to both the optocoupler and the overcurrent protection module interface; the overcurrent protection module interface is connected to the MCU.

4. The electric vehicle insulation resistance simulation circuit according to claim 3, characterized in that, The overcurrent protection module has a protection threshold of 10mA. The sampling resistor is a high-precision resistor. When current flows through the main circuit, a voltage difference will be generated across the sampling resistor according to Ohm's law, and this voltage difference is directly applied to the optocoupler. When the main circuit current exceeds the protection threshold, i.e., the voltage across the sampling resistor is high enough, the optocoupler conducts. After the optocoupler conducts, the optocoupler level switches from the high level of the pull-up resistor to the low level. The overcurrent protection module interface outputs a low level, and then outputs an overcurrent fault signal to the MCU through the overcurrent protection module interface. Upon receiving the fault signal, the MCU immediately controls the main circuit relay to disconnect the main circuit, thereby cutting off the current and realizing overcurrent protection.

5. The electric vehicle insulation resistance simulation circuit according to claim 2, characterized in that, The resistor array in the resistor array and relay module includes R1, R2, R3, ..., R20, where R1 has a resistance of 100Ω, R2 has a resistance of 200Ω, R3 has a resistance of 400Ω, ..., and R20 has a resistance of 52428.8kΩ, which can simulate a resistance range of 100Ω to 100MΩ in 100Ω increments, meeting the BMS's testing requirements for different insulation resistances.

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