BEV electric drive system and active discharge control method thereof

Abstract

The invention discloses a BEV electric drive system and an active discharge control method thereof, and the method comprises the steps: entering an active discharge execution mode when a motor controller receives a closing signal and a main relay state signal is disconnection; if the rotating speed of the motor controller is smaller than or equal to the preset rotating speed, entering a motor winding to execute an active discharging strategy; if the rotating speed is greater than the preset rotating speed, entering a hardware active discharge resistor to execute an active discharge strategy, and setting an active discharge resistor protection strategy; detecting a bus voltage value sampled and fed back by a bus voltage sampling sensor in real time, and if a preset time difference value from entering the active discharge execution mode to the moment that the bus voltage is smaller than a preset voltage value is smaller than preset time and a closing signal is still received, entering an active discharge completion mode; and if the closing signal is not received after entering the active discharge completion mode, entering an active discharge non-execution mode. The high-voltage safety performance of the whole vehicle and a power system is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of safety of power systems of new energy vehicles, and in particular relates to a BEV electric drive system and an active discharge control method thereof. Background Art

[0002] GB / T 18488-2024, Drive Motor System for Electric Vehicles, defines that the electric drive system should discharge the high voltage of the bus support capacitor to below 60V within 5 seconds when performing the active discharge function; in order to quickly reduce the bus support capacitor voltage to below the safe voltage, some existing methods in current technology mainly use the motor winding coil as the discharge energy carrier, and the discharge current flows through the motor winding, and the energy on the bus capacitor is converted from electrical energy to heat energy and consumed in the form of winding heating; however, the above method has certain limitations. In scenarios such as vehicle operation or collision, active discharge through the motor winding will be limited, and active discharge through the motor winding is more suitable for ultra-low speed or stationary vehicle conditions. Summary of the invention

[0003] The purpose of the present invention is to provide a BEV electric drive system and an active discharge control method thereof, which can safely and reliably realize the active release of high-voltage energy of the busbar support capacitor in the full speed range, greatly improving the high-voltage safety performance of the whole vehicle and the power system.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a BEV electric drive system active discharge control method, comprising: When the motor controller receives the shutdown signal and the main relay status signal sent by the battery management system is disconnected, the motor controller enters the active discharge execution mode; If the motor controller's own speed is less than or equal to the preset speed, the motor controller enters the motor winding to execute an active discharge strategy and determines the stator current torque current component and the stator current excitation component; If the motor controller's own speed is greater than the preset speed, the motor controller executes an active discharge strategy through the active discharge resistor in the hardware loop; The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the preset time difference from the time the motor controller enters the active discharge execution mode to the time the bus voltage is less than the preset voltage value is less than the preset time and the shutdown signal is still received, the motor controller enters the active discharge completion mode; if the preset time difference from the time the motor controller enters the active discharge execution mode to the time the bus voltage is less than the preset voltage value is greater than the preset time and the shutdown signal is still received, the motor controller enters the active discharge failure mode.

[0005] The method to determine the stator current excitation component is: Calculate the maximum storage energy of the busbar support capacitor based on the busbar support capacitor capacitance and product specification parameters; The stator current is calculated based on the maximum storage energy of the busbar support capacitor, the total resistance of the motor winding coil, and the preset high-voltage active discharge aging requirements of the electric drive system; The stator current torque current component is preset and assigned, and the stator current excitation component is determined according to the motor vector control principle and the stator current.

[0006] The active discharge strategy is specifically as follows: the motor controller activates the hardware active discharge circuit, performs active discharge through the active discharge resistor on the hardware active discharge circuit, sets the active discharge resistor protection strategy, that is, sets the logic that the active discharge resistor cannot repeatedly perform active discharge within the interval time, and determines the interval time of the active discharge resistor protection strategy.

[0007] The following steps are also included: If the shutdown signal is not received after the motor controller enters the active discharge completion mode, the motor controller enters the active discharge non-execution mode; If the shutdown signal is not received after the motor controller enters the active discharge failure mode, the motor controller enters the active discharge non-execution mode.

[0008] The preset speed range is 300~800rpm, and the interval time range is 30~90s.

[0009] The preset voltage value is 30~150V, and the preset time difference of the preset voltage value is 3~10s.

[0010] A BEV electric drive system is also provided, which includes at least a motor controller, a vehicle controller, a bus voltage sampling sensor, a bus support capacitor and a motor winding coil; wherein, When the motor controller receives a shutdown signal from the vehicle controller and the main relay status signal from the battery management system is disconnected, the motor controller enters the active discharge execution mode; If the motor controller's own speed is less than or equal to the preset speed, the motor controller enters the motor winding to execute an active discharge strategy and determines the stator current torque current component and the stator current excitation component; If the motor controller's own speed is greater than the preset speed, the motor controller enters the hardware active discharge resistor to execute the active discharge strategy, the motor controller activates the hardware active discharge loop, and executes active discharge through the active discharge resistor on the hardware active discharge loop, sets the active discharge resistor protection strategy, that is, sets the logic that the active discharge resistor cannot be repeatedly executed within the interval time, and determines the interval time of the active discharge resistor protection strategy; The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the preset time difference from when the motor controller enters the active discharge execution mode to when the bus voltage is less than the preset voltage value is less than the preset time and a shutdown signal is still received, the motor controller enters the active discharge completion mode; if the motor controller does not receive a shutdown signal after entering the active discharge completion mode, the motor controller enters the active discharge non-execution mode; The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the preset time difference from the time when the motor controller enters the active discharge execution mode to the time when the bus voltage is less than the preset voltage value is greater than the preset time and the shutdown signal is still received, the motor controller enters the active discharge failure mode; if the motor controller does not receive a shutdown signal after entering the active discharge failure mode, the motor controller enters the active discharge non-execution mode.

[0011] The method to determine the stator current excitation component is: Calculate the maximum storage energy of the busbar support capacitor based on the busbar support capacitor capacitance and product specification parameters; The stator current is calculated based on the maximum storage energy of the busbar support capacitor, the total resistance of the motor winding coil, and the preset high-voltage active discharge aging requirements of the electric drive system; The stator current torque current component is preset and assigned, and the stator current excitation component is determined according to the motor vector control principle and the stator current.

[0012] A computer device is also provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above methods when executing the computer program.

[0013] A computer-readable storage medium is also provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention combines the active discharge of motor windings implemented by software with the active discharge of hardware active discharge resistors by setting an active discharge resistor protection strategy, thereby safely and reliably realizing the active release of high-voltage energy of the busbar support capacitor over the full speed range, greatly improving the high-voltage safety performance of the entire vehicle and the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of a flow chart of an embodiment of the present invention; Figure 2 Schematic diagram of the execution of the control method in the embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0017] In various embodiments of the present invention, the motor controller has the following characteristics in various modes: Active discharge not executed mode: The active discharge mode signal fed back by the motor controller to the bus is in the active discharge not executed state; Active discharge execution mode: The motor controller performs winding active discharge or hardware resistor active discharge after logical judgment. At the same time, the active discharge mode signal fed back by the motor controller to the bus is in the active discharge execution state; Active discharge completion mode: The motor controller reduces the high voltage to less than 60V within 5 seconds, and the active discharge mode signal fed back by the motor control to the bus is in the active discharge completion state; Active discharge failure mode: If the motor controller fails to reduce the high voltage to less than 60V within 5 seconds, the motor control will report an active discharge failure fault, and the active discharge mode signal fed back to the bus will be in the active discharge failure state.

[0018] The technical solution of the present invention is: Embodiment 1: A BEV electric drive system active discharge control method, such as Figure 1 and Figure 2 As shown, including: S1. The motor controller receives a shutdown signal from the vehicle controller, which is a shutdown signal (or a collision signal from the body controller, which is an activation signal, or other equivalent signals), and the main relay status signal from the battery management system is disconnected; the motor controller enters the active discharge execution mode from the active discharge non-execution mode; S2. If the motor controller detects and determines that its own speed signal value is less than or equal to 500rpm (calibrable), the motor controller enters the motor winding to execute the active discharge strategy. The motor controller performs a table lookup output control method through the id current table under 336V voltage and the iq current table under 336V voltage as shown in Table 1 and Table 2 (the id / iq current table lookup method is widely used in permanent magnet synchronous motor current control. It mainly presets the id / iq current value under the condition of a fixed voltage and takes the speed / torque command of equal gradient as the horizontal / vertical axis. When controlling the current output, the preset id / iq current value is searched according to the current voltage value and the torque command value, and output as the target current value; wherein the parameter values ​​in Table 1 and Table 2 are only example values ​​when the voltage value is 336V), the output stator current is transmitted on the motor winding coil, and the high-voltage energy on the busbar support capacitor of the motor controller is quickly discharged by the way that the current flows through the wire to generate heat; Table 1

[0019] Table 2

[0020] According to the motor vector control principle, the q-axis current is the stator current torque current component. In the active discharge scenario of the electric drive system, in order to ensure the safety of the vehicle, no torque output is allowed. Therefore, when the motor winding active discharge id / iq table output is executed, the q-axis current is assigned a value of 0A. Confirm the stator current excitation component ID when the motor winding actively discharges ID / IQ and looks up the output table: The maximum storage energy of the busbar support capacitor is calculated as E according to the busbar support capacitor capacitance and product specification parameters; Calculate the total resistance of the motor winding coil as R; According to the energy formula I²Rt=Q, calculate the value of the stator current I, substitute Q=E, then I²Rt=E; According to the high-voltage active discharge time requirement of the electric drive system, t≤5S; Then the stator current, according to the product design and the application requirements of the electric drive product, confirm the value of the expected target active discharge time t, so as to obtain the value of the stator current I; I²=id²+iq², where iq is assigned a value of 0A when performing the winding active discharge table lookup, then |id|=I. Through the above calculation, the value a of id when performing the winding active discharge table lookup is obtained; When the winding active discharge id and iq table lookup is executed, id is assigned a and iq is assigned 0.

[0021] S3. If the motor controller detects and determines that its own speed is greater than 500rpm (calibrable), the motor controller enters the hardware active discharge resistor to execute the active discharge strategy. The motor controller activates the hardware active discharge circuit and executes active discharge through the active discharge resistor on the hardware active discharge circuit. At the same time, in order to avoid repeated active discharge through the active discharge resistor, which may cause overheating or life loss of the active discharge resistor, it is necessary to set the active discharge resistor protection strategy: the logic that the active discharge resistor cannot be repeatedly executed within the software-set interval time b; therefore, when the speed is greater than 500rpm (calibrable) and the time interval from the last active discharge resistor to the active discharge is less than the interval time b, the hardware active discharge will not be executed. It is necessary to wait for the cooling period of the interval time b to make a conditional judgment or wait for the speed to drop below 500rpm (calibrable) to execute active discharge through the motor winding; Confirm the interval time b value of the hardware active discharge resistor protection strategy: The interval time b needs to be confirmed through a large number of tests based on the selection of active discharge resistors, product service life, and high-temperature working characteristics. Considering the service life of the active discharge resistor, it is recommended to reserve sufficient margin to ensure the use time of the resistor. It is generally recommended to set the interval time b to 60 seconds (calibrable). The present invention focuses on the control method of the active discharge logic strategy of the electric drive system, and the calibration confirmation of the above interval time b only provides a calibration idea.

[0022] S4. The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the time difference from when the motor controller enters the active discharge execution mode to when the bus voltage is less than 60V is less than 5s and the mode request command issued by the vehicle controller is still shutdown, the motor controller exits the active discharge execution mode and enters the active discharge completion mode. After the motor controller enters the active discharge completion mode, if the mode command request issued by the vehicle controller is not in shutdown state, the motor controller exits the active discharge completion mode and enters the active discharge non-execution mode. The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the time difference from the motor controller entering the active discharge execution mode to the bus voltage being less than 60V is greater than 5s and the mode request command issued by the vehicle controller is still shutdown, the motor controller exits the active discharge execution mode and enters the active discharge failure mode. When the motor controller is in the active discharge failure mode, if the mode command request issued by the vehicle controller is not in the shutdown state, the motor controller exits the active discharge failure mode and enters the active discharge non-execution mode.

[0023] Embodiment 2: A BEV electric drive system is also provided, which includes at least a motor controller, a vehicle controller, a bus voltage sampling sensor, a bus support capacitor and a motor winding coil; wherein, The motor controller receives a shutdown mode request command from the vehicle controller (or an activation collision signal from the body controller, or other equivalent signals) and the main relay status signal from the battery management system is disconnected; the motor controller enters the active discharge execution mode from the active discharge non-execution mode; If the motor controller detects and determines that its own speed signal value is less than or equal to 500rpm (calibrable), the motor controller enters the motor winding to execute the active discharge strategy. The motor controller outputs the stator current through the ID / IQ current table lookup control method, and transmits it on the motor winding coil. The high-voltage energy on the busbar support capacitor of the motor controller is quickly discharged by the current flowing through the wire to generate heat; According to the motor vector control principle, the q-axis current is the stator current torque current component. In the active discharge scenario of the electric drive system, in order to ensure the safety of the vehicle, no torque output is allowed. Therefore, when the motor winding active discharge id / iq table output is executed, the q-axis current is assigned a value of 0A. Confirm the stator current excitation component ID when the motor winding actively discharges ID / IQ and looks up the output table: The maximum storage energy of the busbar support capacitor is calculated as E according to the busbar support capacitor capacitance and product specification parameters; Calculate the total resistance of the motor winding coil as R; According to the energy formula I²Rt=Q, calculate the value of the stator current I, substitute Q=E, then I²Rt=E; According to the high-voltage active discharge time requirement of the electric drive system, t≤5S; Then the stator current, according to the product design and the application requirements of the electric drive product, confirm the value of the expected target active discharge time t, so as to obtain the value of the stator current I; I²=id²+iq², where iq is assigned a value of 0A when performing the winding active discharge table lookup, then |id|=I. Through the above calculation, the value a of id when performing the winding active discharge table lookup is obtained; When the winding active discharge id and iq table lookup is executed, id is assigned a and iq is assigned 0.

[0024] If the motor controller detects and determines that its own speed is greater than 500rpm (calibrable), the motor controller enters the hardware active discharge resistor to execute the active discharge strategy, and the motor controller activates the hardware active discharge circuit, and performs active discharge through the active discharge resistor on the hardware active discharge circuit; at the same time, in order to avoid repeated active discharge through the active discharge resistor, which may cause overheating damage or life reduction of the active discharge resistor, it is necessary to set the active discharge resistor protection strategy: the logic that the active discharge resistor cannot be repeated within the software-set interval time b; therefore, when the speed is greater than 500rpm (calibrable) and the time interval from the last active discharge resistor to perform active discharge is less than the interval time b, the hardware active discharge will not be performed, and it is necessary to wait for the interval time b cooling period to make a condition judgment or wait for the speed to drop below 500rpm (calibrable) to perform active discharge through the motor winding; Confirm the interval time b value of the hardware active discharge resistor protection strategy: The interval time b needs to be confirmed through a large number of tests based on the selection of active discharge resistors, product service life, and high-temperature working characteristics. Considering the service life of the active discharge resistor, it is recommended to reserve sufficient margin to ensure the use time of the resistor. It is generally recommended to set the interval time b to 60 seconds (calibrable). The present invention focuses on the control method of the active discharge logic strategy of the electric drive system, and the calibration confirmation of the above interval time b only provides a calibration idea.

[0025] The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the time difference from when the motor controller enters the active discharge execution mode to when the bus voltage is less than 60V is less than 5s and the mode request command issued by the vehicle controller is still shutdown, the motor controller exits the active discharge execution mode and enters the active discharge completion mode. After the motor controller enters the active discharge completion mode, if the mode command request issued by the vehicle controller is not in shutdown state, the motor controller exits the active discharge completion mode and enters the active discharge non-execution mode. The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the time difference from the motor controller entering the active discharge execution mode to the bus voltage being less than 60V is greater than 5s and the mode request command issued by the vehicle controller is still shutdown, the motor controller exits the active discharge execution mode and enters the active discharge failure mode. When the motor controller is in the active discharge failure mode, if the mode command request issued by the vehicle controller is not in the shutdown state, the motor controller exits the active discharge failure mode and enters the active discharge non-execution mode.

[0026] Embodiment 3: A computer device is also provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above methods when executing the computer program.

[0027] Embodiment 4: A computer-readable storage medium is also provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0028] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A BEV electric drive system active discharge control method, characterized in that: include: When the motor controller receives the shutdown signal and the main relay status signal sent by the battery management system is disconnected, the motor controller enters the active discharge execution mode; If the motor controller's own speed is less than or equal to the preset speed, the motor controller enters the motor winding to execute an active discharge strategy and determines the stator current torque current component and the stator current excitation component; If the motor controller's own speed is greater than the preset speed, the motor controller executes an active discharge strategy through the active discharge resistor in the hardware loop; The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the preset time difference from when the motor controller enters the active discharge execution mode to when the bus voltage is less than the preset voltage value is less than the preset time and the shutdown signal is still received, the motor controller enters the active discharge completion mode; If the preset time difference from when the motor controller enters the active discharge execution mode to when the bus voltage is less than the preset voltage value is greater than the preset time and the shutdown signal is still received, the motor controller enters the active discharge failure mode.

2. The BEV electric drive system active discharge control method according to claim 1, characterized in that: The method to determine the stator current excitation component is: Calculate the maximum storage energy of the busbar support capacitor based on the busbar support capacitor capacitance and product specification parameters; The stator current is calculated based on the maximum storage energy of the busbar support capacitor, the total resistance of the motor winding coil, and the preset high-voltage active discharge aging requirements of the electric drive system; The stator current torque current component is preset and assigned, and the stator current excitation component is determined according to the motor vector control principle and the stator current.

3. The BEV electric drive system active discharge control method according to claim 1, characterized in that: The active discharge strategy is specifically as follows: the motor controller activates the hardware active discharge circuit, performs active discharge through the active discharge resistor on the hardware active discharge circuit, sets the active discharge resistor protection strategy, that is, sets the logic that the active discharge resistor cannot repeatedly perform active discharge within the interval time, and determines the interval time of the active discharge resistor protection strategy.

4. The BEV electric drive system active discharge control method according to claim 1, characterized in that: The following steps are also included: If the shutdown signal is not received after the motor controller enters the active discharge completion mode, the motor controller enters the active discharge non-execution mode; If the shutdown signal is not received after the motor controller enters the active discharge failure mode, the motor controller enters the active discharge non-execution mode.

5. The BEV electric drive system active discharge control method according to claim 1, characterized in that: The preset speed range is 300~800rpm, and the interval time range is 30~90s.

6. The BEV electric drive system active discharge control method according to claim 1, characterized in that: The preset voltage value is 30~150V, and the preset time difference of the preset voltage value is 3~10s.

7. A BEV electric drive system, characterized in that: At least includes a motor controller, a vehicle controller, a bus voltage sampling sensor, a bus support capacitor and a motor winding coil; wherein, When the motor controller receives a shutdown signal from the vehicle controller and the main relay status signal from the battery management system is disconnected, the motor controller enters the active discharge execution mode; If the motor controller's own speed is less than or equal to the preset speed, the motor controller enters the motor winding to execute an active discharge strategy and determines the stator current torque current component and the stator current excitation component; If the motor controller's own speed is greater than the preset speed, the motor controller enters the hardware active discharge resistor to execute the active discharge strategy, the motor controller activates the hardware active discharge loop, and executes active discharge through the active discharge resistor on the hardware active discharge loop, sets the active discharge resistor protection strategy, that is, sets the logic that the active discharge resistor cannot be repeatedly executed within the interval time, and determines the interval time of the active discharge resistor protection strategy; The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the preset time difference from when the motor controller enters the active discharge execution mode to when the bus voltage is less than the preset voltage value is less than the preset time and a shutdown signal is still received, the motor controller enters the active discharge completion mode; if the motor controller does not receive a shutdown signal after entering the active discharge completion mode, the motor controller enters the active discharge non-execution mode; The motor controller detects the bus voltage value sampled and fed back by the bus voltage sampling sensor in real time. If the preset time difference from the time when the motor controller enters the active discharge execution mode to the time when the bus voltage is less than the preset voltage value is greater than the preset time and the shutdown signal is still received, the motor controller enters the active discharge failure mode; if the motor controller does not receive a shutdown signal after entering the active discharge failure mode, the motor controller enters the active discharge non-execution mode.

8. The BEV electric drive system according to claim 7, characterized in that: The method to determine the stator current excitation component is: Calculate the maximum storage energy of the busbar support capacitor based on the busbar support capacitor capacitance and product specification parameters; The stator current is calculated based on the maximum storage energy of the busbar support capacitor, the total resistance of the motor winding coil, and the preset high-voltage active discharge aging requirements of the electric drive system; The stator current torque current component is preset and assigned, and the stator current excitation component is determined according to the motor vector control principle and the stator current.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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