Method and system for controlling three-phase circuit breaker of electric drive system

Abstract

The invention discloses a control method and system for a three-phase circuit breaker of an electric drive system. The control method comprises the following steps: acquiring a collision signal, a fault signal and a motor running state signal in the electric drive system in real time; when any two of the collision signal, the fault signal and the motor operation state signal are effective flag bits, performing grading risk assessment on the electric driving system based on a preset grading risk assessment strategy so as to output a protection instruction for the electric driving system; the protection instruction comprises a first-level response instruction, a second-level response instruction and a third-level response instruction; and executing corresponding torque limitation, PWM frequency adjustment or motor mode switching operation according to the level of the protection instruction so as to control a three-phase circuit breaker to complete graded protection of the electric drive system. According to the method and the system, the safety and the reliability of the electric driving system are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of safety of electric drive systems for electric vehicles, and in particular to a three-phase circuit breaker control method and system for an electric drive system. Background Art

[0002] With the rapid development of new energy vehicles, the reliability and safety of motor control modules (MCMs), core components of electric drive systems, are crucial. Three-phase circuit breakers, critical protection devices in MCMs, must quickly disconnect the circuit under fault conditions such as short circuits, overloads, and collisions to prevent serious failures such as power module damage and motor winding burnout. However, existing circuit breaker control technologies present numerous challenges. For example, existing technologies suffer from insufficient response speed. Traditional electromagnetic circuit breakers have a mechanical trip time >20ms, and electronic protection algorithms (RMS calculation) have a delay >10ms, making them unable to meet the μs-level short-circuit requirements of SiC power devices (e.g., an 800V platform short-circuit current rise rate >10kA / μs). Furthermore, existing technologies have fixed protection thresholds, unable to distinguish between a motor stall and a normal startup. Furthermore, they lack interlocking with airbag sensors and the BMS high-voltage interlock (post-collision disconnection delay >50ms), making them difficult to meet the high-dynamic and high-safety requirements of new energy vehicles.

[0003] Therefore, how to improve the response speed of circuit breaker control, enhance the adaptability to working conditions, and realize multi-system intelligent linkage has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0004] In order to solve the technical problems existing in the background technology, the present invention proposes a three-phase circuit breaker control method and system for an electric drive system.

[0005] The present invention proposes a three-phase circuit breaker control method for an electric drive system, comprising the following steps:

[0006] Real-time collection of collision signals, fault signals and motor operating status signals in the electric drive system;

[0007] When any two of the collision signal, fault signal, and motor operating status signal are valid flags, a hierarchical risk assessment is performed on the electric drive system based on a preset hierarchical risk assessment strategy to output a protection instruction for the electric drive system; the protection instruction includes a first-level response instruction, a second-level response instruction, and a third-level response instruction;

[0008] According to the level of the protection instruction, corresponding torque limitation, PWM frequency adjustment or motor mode switching operation is performed to control the three-phase circuit breaker to complete the hierarchical protection of the electric drive system.

[0009] Preferably, the preset hierarchical risk assessment strategy specifically includes:

[0010] When the detected temperature of the SiC module in the electric drive system is greater than a preset first threshold, generating a first-level response instruction;

[0011] When the detected current imbalance rate of the three-phase current is greater than the preset second threshold and lasts for x ms or the bus voltage fluctuation is greater than the preset third threshold and lasts for y ms, a secondary response instruction is generated;

[0012] When the collision signal and / or the fault signal is a valid flag and the hardware current in the electric drive system is greater than a preset fourth threshold, a third-level response instruction is generated.

[0013] Preferably, when the protection instruction is specifically a first-level response instruction, the motor torque in the electric drive system is limited to 300 Nm.

[0014] Preferably, when the protection instruction is specifically a secondary response instruction, the PWM carrier frequency in the electric drive system is stepped down, wherein when the current imbalance rate is between 15% and 20%, the PWM carrier frequency is lowered from 10kHz to 8kHz; when the current imbalance rate is greater than 20%, the PWM carrier frequency is lowered from 10kHz to 5kHz.

[0015] Preferably, when the protection instruction is specifically a third-level response instruction, if the motor speed is less than 1500rpm, the motor in the electric drive system is controlled to enter the free sliding mode; if the motor speed is ≥1500rpm, the motor is controlled to enter the active short-circuit mode; if the collision signal and the fault signal are both valid flags, the circuit breaker in the electric drive system is controlled to disconnect.

[0016] Preferably, the collision signal is a hard-wired signal of the airbag control module or collision sensor in the electric drive system that has been de-jittered and filtered; the fault signal includes CAN message signals of battery overtemperature, sensor failure, and torque abnormality; the motor operating status signal includes motor speed, bus voltage, phase current, and SiC module temperature.

[0017] Preferably, it also includes:

[0018] When any one of the collision signal, fault signal and motor operation status signal triggers the valid flag, the system checks the other two types of signals in parallel. If any one of the other two types of signals triggers the valid flag at the same time, the circuit breaker is disconnected, otherwise the current state is maintained and no action is taken.

[0019] The present invention proposes a three-phase circuit breaker control system for an electric drive system, comprising:

[0020] Signal acquisition module, used to collect collision signals, fault signals and motor operation status signals in the electric drive system in real time;

[0021] a control module configured to, when any two of the collision signal, the fault signal, and the motor operating status signal are valid flags, perform a hierarchical risk assessment on the electric drive system based on a preset hierarchical risk assessment strategy to output a protection instruction for the electric drive system; the protection instruction includes a first-level response instruction, a second-level response instruction, and a third-level response instruction;

[0022] The output module is used to execute corresponding torque limitation, PWM frequency adjustment or motor mode switching operations according to the level of the protection instruction to control the three-phase circuit breaker to complete the hierarchical protection of the electric drive system.

[0023] In the present invention, a three-phase circuit breaker control method and system for an electric drive system are proposed. This solution realizes short-circuit protection, high-voltage arc suppression and aging adaptation of SiC modules through an electronic-mechanical hybrid disconnection architecture, combined with a safety decision-making mechanism of hierarchical risk assessment, anti-false triggering verification and multi-signal linkage control, and significantly improves the safety and reliability of the electric drive system. Through hierarchical protection logic and dynamic threshold adjustment, different fault types and motor operating states can be identified, motor stalling and normal startup can be distinguished, and corresponding protection actions can be taken for different fault levels, thereby improving the system's adaptability to complex working conditions. It is linked with multiple systems such as airbag sensors, BMS, VCU, etc., and the circuit breaker is disconnected after the collision signal is triggered, which solves the problem of disconnection delay after collision in the prior art. It has a complete anti-false triggering mechanism to ensure the safe and reliable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the working process of a three-phase circuit breaker control method for an electric drive system proposed by the present invention;

[0025] Figure 2 This is a schematic diagram of the system architecture of a three-phase circuit breaker control system for an electric drive system proposed by the present invention;

[0026] Figure 3 This is a structural schematic diagram of an implementation scheme of a three-phase circuit breaker control system for an electric drive system proposed by the present invention;

[0027] Figure 4 This is a waveform diagram of an implementation of a three-phase circuit breaker control system for an electric drive system proposed by the present invention. DETAILED DESCRIPTION

[0028] Reference Figure 1-4 The present invention proposes a three-phase circuit breaker control method for an electric drive system, comprising the following steps:

[0029] S1. Real-time collection of collision signals, fault signals and motor operation status signals in the electric drive system.

[0030] Specifically, the collision signal is the hard-wired signal of the airbag control module or collision sensor in the electric drive system after de-jitter filtering; the fault signal includes the CAN message signal of battery overtemperature, sensor failure, and torque abnormality; the motor operating status signal includes the motor speed, bus voltage, phase current and SiC module temperature.

[0031] S2. When any two of the collision signal, fault signal, and motor operating status signal are valid flags, a hierarchical risk assessment is performed on the electric drive system based on a preset hierarchical risk assessment strategy to output protection instructions for the electric drive system; the protection instructions include a first-level response instruction, a second-level response instruction, and a third-level response instruction.

[0032] In this embodiment, the preset hierarchical risk assessment strategy specifically includes:

[0033] When the detected temperature of the SiC module in the electric drive system is greater than a preset first threshold, generating a first-level response instruction;

[0034] When the detected current imbalance rate of the three-phase current is greater than the preset second threshold and lasts for x ms or the bus voltage fluctuation is greater than the preset third threshold and lasts for y ms, a secondary response instruction is generated;

[0035] When the collision signal and / or the fault signal is a valid flag and the hardware current in the electric drive system is greater than a preset fourth threshold, a third-level response instruction is generated.

[0036] Specifically, the preset first threshold is 105° C., and the threshold is adjustable. When the detected current imbalance rate of the three-phase current is greater than 15% and lasts for 10 ms or the bus voltage fluctuation is greater than ±10% and lasts for 5 ms, a secondary response instruction is generated.

[0037] In this embodiment, when the protection instruction is specifically a first-level response instruction, the motor torque in the electric drive system is limited to 300 Nm.

[0038] In this embodiment, when the protection instruction is specifically a secondary response instruction, the PWM carrier frequency in the electric drive system is stepped down, wherein, when the current imbalance rate is between 15% and 20%, the PWM carrier frequency is reduced from 10kHz to 8kHz; when the current imbalance rate is greater than 20%, the PWM carrier frequency is reduced from 10kHz to 5kHz.

[0039] In this embodiment, when the protection instruction is specifically a third-level response instruction, if the motor speed is less than 1500rpm, the motor in the electric drive system is controlled to enter the free sliding mode; if the motor speed is ≥1500rpm, the motor is controlled to enter the active short-circuit mode; if the collision signal and the fault signal are both valid flags, the circuit breaker in the electric drive system is controlled to disconnect.

[0040] S3. According to the protection instruction level, the corresponding torque limit, PWM frequency adjustment or motor mode switching operation is executed to control the three-phase circuit breaker to complete the hierarchical protection of the electric drive system.

[0041] In this embodiment, it also includes:

[0042] S4. When any one of the collision signal, fault signal and motor operation status signal triggers the valid flag, the system checks the other two types of signals in parallel. If any one of the other two types of signals triggers the valid flag at the same time, the circuit breaker is disconnected; otherwise, the current state is maintained and no action is taken.

[0043] In this embodiment, the method further includes: storing the protection operation in a non-volatile memory (MSC); and sending the fault code to the vehicle network via CANFD.

[0044] Reference Figure 1-4 The present invention proposes a three-phase circuit breaker control system for an electric drive system, comprising:

[0045] Signal acquisition module, used to collect collision signals, fault signals and motor operation status signals in the electric drive system in real time;

[0046] a control module configured to, when any two of the collision signal, the fault signal, and the motor operating status signal are valid flags, perform a hierarchical risk assessment on the electric drive system based on a preset hierarchical risk assessment strategy to output a protection instruction for the electric drive system; the protection instruction includes a first-level response instruction, a second-level response instruction, and a third-level response instruction;

[0047] The output module is used to execute corresponding torque limitation, PWM frequency adjustment or motor mode switching operations according to the protection instruction level to control the three-phase circuit breaker to complete the hierarchical protection of the electric drive system.

[0048] Specifically, the circuit breaker uses a hybrid disconnection strategy: first, electronic disconnection is achieved through the MOS tube on the SiC module (response time < 1μs); then mechanical disconnection is completed through the magnetic arc blowing mechanism (operation time < 2ms). The circuit breaker can use excitation fuses and pyrotechnic circuit breakers. Figure 3 As shown, the control module uses a dual-core lockstep MCU for signal redundancy. The hardware comparator CMP in the control module directly triggers emergency disconnection. A safe state retention circuit ensures that the contacts remain in the disconnected position after power failure. The time from collision signal triggering to full circuit breaker disconnection is ≤ 3ms. This system works in conjunction with the BMS high-voltage interlock, with an error of ≤ ±100μs.

[0049] In this embodiment, a current sensor is provided between the circuit breaker and the control module to feedback the breaking current change of the circuit breaker, such as Figure 4FIG. 1 shows a waveform diagram of an embodiment of a circuit breaker breaking test, wherein the phase current is 100A.

[0050] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A three-phase circuit breaker control method for an electric drive system, characterized in that: The following steps are involved: Real-time collection of collision signals, fault signals and motor operating status signals in the electric drive system; When any two of the collision signal, fault signal, and motor operating status signal are valid flags, a hierarchical risk assessment is performed on the electric drive system based on a preset hierarchical risk assessment strategy to output a protection instruction for the electric drive system; the protection instruction includes a first-level response instruction, a second-level response instruction, and a third-level response instruction; According to the level of the protection instruction, corresponding torque limitation, PWM frequency adjustment or motor mode switching operation is performed to control the three-phase circuit breaker to complete the hierarchical protection of the electric drive system.

2. The electric drive system three-phase circuit breaker control method according to claim 1, characterized in that: The preset hierarchical risk assessment strategy specifically includes: When the detected temperature of the SiC module in the electric drive system is greater than a preset first threshold, generating a first-level response instruction; When the detected current imbalance rate of the three-phase current is greater than the preset second threshold and lasts for x ms or the bus voltage fluctuation is greater than the preset third threshold and lasts for y ms, a secondary response instruction is generated; When the collision signal and / or the fault signal is a valid flag and the hardware current in the electric drive system is greater than a preset fourth threshold, a third-level response instruction is generated.

3. The electric drive system three-phase circuit breaker control method according to claim 2, characterized in that: When the protection instruction is specifically a first-level response instruction, the motor torque in the electric drive system is limited to 300 Nm.

4. The electric drive system three-phase circuit breaker control method according to claim 2, characterized in that: When the protection instruction is specifically a secondary response instruction, the PWM carrier frequency in the electric drive system is stepped down. When the current imbalance rate is between 15% and 20%, the PWM carrier frequency is reduced from 10kHz to 8kHz; when the current imbalance rate is greater than 20%, the PWM carrier frequency is reduced from 10kHz to 5kHz.

5. The electric drive system three-phase circuit breaker control method according to claim 2, characterized in that: When the protection instruction is specifically a third-level response instruction, if the motor speed is less than 1500rpm, the motor in the electric drive system is controlled to enter the free sliding mode; if the motor speed is ≥1500rpm, the motor is controlled to enter the active short-circuit mode; if the collision signal and the fault signal are both valid flags, the circuit breaker in the electric drive system is controlled to disconnect.

6. The electric drive system three-phase circuit breaker control method according to claim 1, characterized in that: in, The collision signal is a hard-wired signal of the airbag control module or collision sensor in the electric drive system that has been de-jittered and filtered; the fault signal includes CAN message signals of battery overtemperature, sensor failure, and torque abnormality; the motor operating status signal includes motor speed, bus voltage, phase current, and SiC module temperature.

7. The electric drive system three-phase circuit breaker control method according to claim 1, characterized in that: Also includes: When any one of the collision signal, fault signal and motor operation status signal triggers the valid flag, the system checks the other two types of signals in parallel. If any one of the other two types of signals triggers the valid flag at the same time, the circuit breaker is disconnected, otherwise the current state is maintained and no action is taken.

8. A three-phase circuit breaker control system for an electric drive system, characterized in that: include: Signal acquisition module, used to collect collision signals, fault signals and motor operation status signals in the electric drive system in real time; a control module configured to, when any two of the collision signal, the fault signal, and the motor operating status signal are valid flags, perform a hierarchical risk assessment on the electric drive system based on a preset hierarchical risk assessment strategy to output a protection instruction for the electric drive system; the protection instruction includes a first-level response instruction, a second-level response instruction, and a third-level response instruction; The output module is used to execute corresponding torque limitation, PWM frequency adjustment or motor mode switching operations according to the level of the protection instruction to control the three-phase circuit breaker to complete the hierarchical protection of the electric drive system.

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