An electric vehicle bus voltage bleed control method and system

Abstract

This invention provides a method and system for controlling bus voltage discharge in electric vehicles. The method includes the following steps: determining the bus voltage status based on the high-voltage safety detection module, whereby the bus voltage status includes the presence of a bus voltage comparison fault and the absence of a bus voltage comparison fault; combining the bus voltage status with a discharge request signal received by the motor controller to discharge the bus voltage, and feeding back the discharge completion status to the vehicle controller. The discharge request signal includes an active discharge request signal and a collision signal. This invention, while controlling development costs, uses the motor controller to determine the presence of a bus voltage comparison fault and a collision signal, enabling the design of corresponding bus voltage discharge strategies based on different discharge conditions. This ensures the reliability of active discharge of the entire vehicle in the event of a collision during driving, improving the high-voltage safety of the vehicle and the safety of the user.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and specifically to a method and system for controlling bus voltage discharge in electric vehicles. Background Technology

[0002] Pure electric vehicles are electric vehicles powered entirely by batteries, with operating voltages reaching hundreds of volts, far exceeding safe voltage levels. Furthermore, the discharge current of the high-voltage system can reach tens or even hundreds of amperes during operation. When insulation failure, short circuits, or leakage occur in the high-voltage circuit, it can directly cause significant harm to the personal safety and property of the driver and passengers. Therefore, the electrical system safety of pure electric vehicles has become a crucial indicator for evaluating their overall safety.

[0003] Chinese invention patent CN113619393A discloses an active discharge control method and system for electric vehicles. The control method includes, after the vehicle is normally powered down, the vehicle controller sends a power-down request to the battery manager and a first active discharge request to the motor controller. Upon receiving the power-down request, the battery manager controls the vehicle to unload; upon completion of unloading, it controls the main positive and main negative contactors to disconnect and feeds back the disconnection status information of the main positive and main negative contactors to the motor controller and the vehicle controller. Upon receiving the first active discharge request, the motor controller unloads the motor; upon completion of unloading, if the aforementioned disconnection status information is present, a first discharge is performed; if the first discharge fails, a second discharge is performed; if the second discharge also fails, discharge is prohibited and a failure fault message is issued. This method aims to improve the high-voltage safety of the vehicle and the safety of the user by sending power-down requests to the battery manager and second active discharge requests to the motor controller. However, this solution does not consider the potential dangers of insulation failure and short circuits caused by accidents such as collisions, rollovers, or collisions with other vehicles while the vehicle is charging. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for controlling bus voltage discharge in electric vehicles, the method comprising the following steps:

[0005] S1. Determine if there is a bus voltage comparison fault in the bus voltage status, then determine if the motor controller has received a collision signal, and discharge the bus voltage according to the discharge request signal received by the motor controller.

[0006] S11. When a bus voltage comparison fault exists in the bus voltage status, if the motor controller receives a collision signal, it performs resistor discharge; if the motor controller does not receive a collision signal, it performs corresponding bus voltage discharge according to the type of bus voltage comparison fault.

[0007] S12. When there is no bus voltage comparison fault in the bus voltage status, if the motor controller receives a collision signal, it will perform resistor discharge; if the motor controller does not receive a collision signal, it will perform winding discharge.

[0008] S2. Detect whether the bus voltage after discharge is a safe voltage and report the discharge completion status to the vehicle controller.

[0009] Furthermore, the bus voltage comparison fault in S1 includes two types: two-way bus voltage comparison verification fault and one-way bus voltage range verification fault. The one-way bus voltage range verification fault includes a high-precision bus voltage range verification fault and a low-precision bus voltage range verification fault. When the one-way bus voltage range verification fault occurs, one bus voltage can be selected for zero torque control.

[0010] Furthermore, the phrase "when there is a bus voltage comparison fault in the bus voltage state and the motor controller does not receive a collision signal" in S11 specifically includes:

[0011] When the type of bus voltage comparison fault is a two-way bus voltage comparison verification fault, resistor discharge is performed.

[0012] If the type of bus voltage comparison fault is a bus voltage range verification fault, then winding discharge is performed.

[0013] Furthermore, S2, "detecting whether the bus voltage after discharge is a safe voltage and feeding back the discharge completion status to the vehicle controller," includes:

[0014] S21. When the motor controller does not receive a collision signal, if the bus voltage after the winding discharge is detected to be a safe voltage, a discharge success signal is fed back to the vehicle controller; if the bus voltage after the winding discharge is detected to be a non-safe voltage, resistor discharge is further performed, and the bus voltage after the resistor discharge is further detected to be a safe voltage. If the bus voltage after the resistor discharge is detected to be a safe voltage, a discharge success signal is fed back to the vehicle controller; if the bus voltage after the resistor discharge is detected to be a non-safe voltage, a discharge failure signal is fed back to the vehicle controller.

[0015] S22. When the motor controller receives a collision signal, if the bus voltage after the resistor discharges is detected to be a safe voltage, a discharge success signal is fed back to the vehicle controller; if the bus voltage after the resistor discharges is detected to be an unsafe voltage, a discharge failure signal is fed back to the vehicle controller.

[0016] Furthermore, when there is a bus voltage comparison fault in the bus voltage status, and the type of the bus voltage comparison fault is a two-way bus voltage comparison verification fault, a discharge failure signal is fed back to the vehicle controller after the resistor discharge is performed.

[0017] Furthermore, the safe voltage is below 55V.

[0018] An electric vehicle bus voltage discharge control system is provided, applied in the aforementioned electric vehicle bus voltage discharge control method, the system comprising:

[0019] The vehicle controller is used to determine the vehicle's discharge status and send active discharge requests.

[0020] The high-voltage safety detection module is used to detect whether there is a bus voltage comparison fault in the bus voltage status; and

[0021] The motor controller is used to receive collision signals, and the vehicle controller sends an active discharge request to the motor controller according to the vehicle's discharge status.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention, while controlling development costs, uses a motor controller to determine whether there is a bus voltage comparison fault and collision signal, and implements a bus voltage discharge strategy designed according to different discharge conditions. This ensures the reliability of the vehicle's active discharge in the event of a collision accident during driving, and improves the high voltage safety of the vehicle and the safety of the user. Attached Figure Description

[0024] Figure 1 To develop a flowchart for active discharge conditions;

[0025] Figure 2 A flowchart for the invention of collision discharge conditions. Detailed Implementation

[0026] To make the technical solutions and effects of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0027] This invention aims to provide a method for controlling bus voltage discharge in electric vehicles. The electric drive system includes a vehicle controller, a motor controller, and a high-voltage safety detection module. The high-voltage safety detection module determines whether to activate the active discharge function and discharge monitoring function based on the discharge request signal and the collision signal input signal. It judges whether the electric drive system has generated unexpected high voltage by whether the bus voltage drops below the safe voltage of 55V within 5 seconds, and feeds back the discharge status signal to the vehicle controller.

[0028] Depending on whether the motor controller receives a collision signal, the operation is divided into active discharge mode and collision discharge mode, and different bus discharge strategies are executed.

[0029] During the discharge process, the high-voltage safety detection module determines the bus voltage status, specifically whether a bus voltage comparison fault has occurred. A bus voltage comparison fault can be categorized into two bus voltage comparison verification faults and one bus voltage range verification fault. The bus voltage range verification fault includes both high-precision and low-precision bus voltage range verification faults. When a bus voltage range verification fault occurs, one bus voltage can be selected for zero-torque control. The vehicle controller sends an active discharge request signal, which includes both an active discharge request signal and a collision signal. The motor controller receives the discharge request signal and performs bus voltage discharge. The high-voltage safety detection module then feeds back the discharge completion status information to the vehicle controller based on the bus voltage detection results.

[0030] There are two methods for discharging bus voltage: winding discharge and resistor discharge. Winding discharge utilizes the losses in the stator windings and power devices of the motor, given a given motor D-axis current Id, to release the energy within the capacitor. The winding discharge method is designed to reduce the bus voltage from the maximum allowable operating voltage to below 55V within time t1. Resistor discharge, on the other hand, uses a designed discharge resistor to reduce the bus voltage from the maximum allowable operating voltage to below 55V within time t2.

[0031] like Figure 1 As shown, the bus voltage discharge strategy under active discharge conditions has the following three cases:

[0032] If the high-voltage safety detection module determines that there is a bus voltage comparison fault, and it is a bus voltage range verification fault, and the motor controller receives an active discharge request signal, it will perform winding discharge. If the high-voltage safety detection module detects that the bus voltage after winding discharge is a safe voltage, it will send a discharge success signal to the vehicle controller; otherwise, it will perform resistor discharge. If the high-voltage safety detection module detects that the bus voltage after resistor discharge is a safe voltage, it will send a discharge success signal to the vehicle controller; otherwise, it will send a discharge failure signal to the vehicle controller.

[0033] If the high-voltage safety detection module determines that there is a bus voltage comparison fault, and it is a two-bus voltage comparison verification fault, and the motor controller receives an active discharge request signal, it will perform resistor discharge and send a discharge failure signal back to the vehicle controller.

[0034] If the high-voltage safety detection module determines that there is no bus voltage comparison fault, and the motor controller receives an active discharge signal, it will discharge the windings. If the high-voltage safety detection module detects that the bus voltage after the winding discharge is a safe voltage, it will send a discharge success signal to the vehicle controller; otherwise, it will perform resistor discharge. If the high-voltage safety detection module detects that the bus voltage after the resistor discharge is a safe voltage, it will send a discharge success signal to the vehicle controller; otherwise, it will send a discharge failure signal to the vehicle controller.

[0035] like Figure 2 As shown, the bus voltage discharge strategy under collision discharge conditions has the following three cases:

[0036] If the high-voltage safety detection module determines that there is a bus voltage comparison fault, and it is a bus voltage range verification fault, when the motor controller receives the collision signal, the motor controller receives the active discharge request signal and performs resistor discharge. If the high-voltage safety detection module detects that the bus voltage after resistor discharge is a safe voltage, it sends a discharge success signal to the vehicle controller; otherwise, it sends a discharge failure signal to the vehicle controller.

[0037] If the high-voltage safety detection module determines that there is a bus voltage comparison fault, and it is a two-bus voltage comparison verification fault, when the motor controller receives the collision signal, the motor controller receives the active discharge request signal, performs resistor discharge, and sends a discharge failure signal back to the vehicle controller.

[0038] If the high-voltage safety detection module determines that there is no bus voltage comparison fault, and the motor controller receives a collision signal, the motor controller receives an active discharge request signal and performs resistor discharge. If the high-voltage safety detection module detects that the bus voltage after resistor discharge is a safe voltage, it sends a discharge success signal to the vehicle controller; otherwise, it sends a discharge failure signal to the vehicle controller.

[0039] This invention, while controlling development costs, uses a motor controller to determine whether there is a bus voltage comparison fault and collision signal, and implements a bus voltage discharge strategy designed according to different discharge conditions. This ensures the reliability of the vehicle's active discharge in the event of a collision accident during driving, and improves the high voltage safety of the vehicle and the safety of the user.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling bus voltage discharge in electric vehicles, characterized in that, The method includes the following steps: S1. Determine if a bus voltage comparison fault exists, then determine if the motor controller receives a collision signal, and discharge the bus voltage according to the discharge request signal received by the motor controller; the bus voltage comparison fault in S1 includes two types: two-way bus voltage comparison verification fault and one-way bus voltage range verification fault. The one-way bus voltage range verification fault includes high-precision bus voltage range verification fault and low-precision bus voltage range verification fault; when the one-way bus voltage range verification fault occurs, one bus voltage can be selected for zero torque control; S11. When a bus voltage comparison fault exists in the bus voltage state, if the motor controller receives a collision signal, it performs resistor discharge; if the motor controller does not receive a collision signal, it performs corresponding bus voltage discharge according to the type of the bus voltage comparison fault. Specifically, S11 includes: when the type of the bus voltage comparison fault is a two-way bus voltage comparison verification fault, resistor discharge is performed; when the type of the bus voltage comparison fault is a one-way bus voltage range verification fault, winding discharge is performed. S12. When there is no bus voltage comparison fault in the bus voltage status, if the motor controller receives a collision signal, it will perform resistor discharge; if the motor controller does not receive a collision signal, it will perform winding discharge. S2. Detect whether the bus voltage after discharge is a safe voltage, and report the discharge completion status to the vehicle controller; specifically including: S21. When the motor controller does not receive a collision signal, if the bus voltage after the winding discharge is detected to be a safe voltage, a discharge success signal is fed back to the vehicle controller; if the bus voltage after the winding discharge is detected to be a non-safe voltage, resistor discharge is further performed, and the bus voltage after the resistor discharge is further detected to be a safe voltage. If the bus voltage after the resistor discharge is detected to be a safe voltage, a discharge success signal is fed back to the vehicle controller; if the bus voltage after the resistor discharge is detected to be a non-safe voltage, a discharge failure signal is fed back to the vehicle controller. S22. When the motor controller receives a collision signal, if the bus voltage after the resistor discharges is detected to be a safe voltage, a discharge success signal is fed back to the vehicle controller; if the bus voltage after the resistor discharges is detected to be an unsafe voltage, a discharge failure signal is fed back to the vehicle controller.

2. The electric vehicle bus voltage discharge control method according to claim 1, characterized in that, When a bus voltage comparison fault exists in the bus voltage status, and the type of the bus voltage comparison fault is a two-way bus voltage comparison verification fault, a discharge failure signal is fed back to the vehicle controller after resistor discharge is performed.

3. The electric vehicle bus voltage discharge control method according to claim 1, characterized in that, The safe voltage is below 55V.

4. An electric vehicle bus voltage discharge control system, applied in the electric vehicle bus voltage discharge control method according to any one of claims 1-3, characterized in that, The system includes: The vehicle controller is used to determine the vehicle's discharge status and send active discharge requests. The high-voltage safety detection module is used to detect whether there is a bus voltage comparison fault in the bus voltage status; and The motor controller is used to receive collision signals, and the vehicle controller sends an active discharge request to the motor controller according to the vehicle's discharge status.

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