Motor controller active discharge method and device and storage medium

Abstract

The present application relates to the field of motor drive control of electric engineering machinery vehicles, commercial vehicles, passenger vehicles and the like, and particularly relates to a motor controller active discharge method, device and storage medium. The active discharge method of the present application sets the direct-axis current command value and the quadrature-axis current command value to zero to control the motor to not generate a fundamental frequency current, and the high-frequency current generated by the positive and negative symmetric high-frequency square wave voltage superimposed with the direct-axis fundamental frequency voltage command value consumes the DC side capacitor energy, the average value of the high-frequency current is zero, and whether the rotor position is correct or not, the average value of the generated current and the average value of the torque are also zero, thereby realizing safe discharge in the case of position sensor failure or without a position sensor.

Description

Technical Field

[0001] This invention relates to the field of motor drive control for electric engineering machinery vehicles, commercial vehicles, passenger vehicles, etc., and specifically to a method, device, and storage medium for active discharge of a motor controller. Background Technology

[0002] The motor controller is a crucial component of the main drive and auxiliary drive systems in pure electric vehicles, hybrid electric vehicles, and range-extended electric vehicles. With the development of new energy vehicles, industry and regulations are imposing increasingly stringent safety requirements. When a vehicle stops and loses power or malfunctions, it is essential to quickly and safely discharge any residual high-voltage electricity on the DC bus capacitor of the motor controller to prevent electric shock accidents to the vehicle owner or maintenance personnel.

[0003] A widely used technology in the industry is to control the direct-axis current output of the motor through a current loop, allowing the motor to dissipate the energy of the bus capacitor through current without generating quadrature-axis torque current. This solution is simple to implement, and the discharge rate can be adjusted by setting the magnitude of the direct-axis current.

[0004] However, the correct implementation of this solution depends on the correct rotor position. If the position sensor is damaged or malfunctions, the position sensor zero position deviates, or there is no position sensor, the direct shaft position will be incorrectly positioned, causing the motor to generate torque current on the actual quadrature shaft. This results in the motor outputting unexpected torque, which can lead to abnormal gear meshing noise in the reduction mechanism or, in severe cases, vehicle jerking, endangering personal safety and property. Furthermore, if this motor controller is used in hybrid transmissions or range extenders where the motor is connected to the engine, it may cause the engine to slightly reverse.

[0005] Existing technical solutions mainly fall into three categories. The first category uses a dedicated hardware discharge circuit to control the conduction of a transistor and discharge resistors to dissipate the energy of the bus capacitor. The second category dissipates the energy of the bus capacitor without outputting quadrature-axis torque current by controlling the motor to generate direct-axis current. The third category achieves discharge by controlling the self-dissipation of IGBTs (Insulated Gate Bipolar Transistors, which form a three-phase inverter circuit that converts DC power from the battery into three-phase AC power to drive an AC motor).

[0006] Solution 1: This solution is typical of the first major category. Addressing the issue of active discharge in motor controllers, the invention patent "CN201810689686.8 - Discharge Control Circuit and Active Discharge Circuit for Capacitors in Motor Controllers" provides a solution through a specially designed hardware discharge circuit. This discharge control circuit includes a capacitor C1, a transistor Q1, and an optocoupler U1. One end of capacitor C1 receives the active discharge signal transmitted by the motor controller in square wave form, and the other end is connected to the base of transistor Q1. The emitter of transistor Q1 is grounded, and the collector is connected to the input terminal of optocoupler U1. The output terminal of optocoupler U1 is connected to the control terminal of the active discharge circuit of the capacitor in the motor controller. This embodiment of the invention, through the cooperation of capacitor C1 and transistor Q1, uses the capacitor charging and discharging process to transmit the active discharge signal, thereby controlling the transistor to conduct the optocoupler to achieve active discharge control of the bus capacitor. This enables rapid active discharge of the bus capacitor while effectively preventing false triggering of the discharge control circuit.

[0007] Option 2: This option is typical of the second major category of winding discharge schemes. Regarding the issue of active discharge by the motor controller, the invention patent "CN201911342375.5 - Bus Voltage Control Method and System for Vehicle Motors" is the most common winding discharge scheme in the industry. After receiving the active discharge command, the motor controller sets the q-axis current to 0A and the d-axis current to a fixed current. By generating a weak magnetic current in the motor without generating torque current, the energy of the bus capacitor is dissipated as heat in the motor windings. This scheme is the simplest to implement, requiring no additional hardware costs or overly complex program logic.

[0008] Option 3: This option belongs to the third category of IGBT self-dissipation discharge. The invention patent "CN201710433871.6 - An Active Discharge System for a Motor Controller" controls the upper bridge IGBT to enter the shoot-through state and the lower bridge IGBT to enter the linear region, thereby dissipating the energy of the bus capacitor without using additional hardware current.

[0009] The main drawback of Scheme 1 is the need for additional hardware circuitry to implement the discharge function, increasing both hardware costs and system complexity. Furthermore, this scheme cannot control the discharge speed, and the discharge capacity cannot be debugged or modified after the hardware design is finalized. Scheme 2, with its advantages of no hardware cost and adjustable discharge speed via the quadrature-axis current, is widely used in the industry. However, in sensorless control scenarios or when the position sensor is damaged, there is a possibility of failure to locate the direct axis or random deviations in positioning. If the output discharge current vector differs from the actual d-axis by approximately ±90°, a large quadrature-axis current component will be generated, resulting in uncontrollable torque pulses. This can cause abnormal noise in the reducer meshing or, in severe cases, vehicle jerking. Scheme 3 is more difficult to implement and carries the risk of IGBT up-and-down bridge shoot-through. Summary of the Invention

[0010] The purpose of this invention is to provide a method, device, and storage medium for active discharge of a motor controller. The direct-axis current command value and the quadrature-axis current command value are both set to zero to control the motor to not generate the base frequency current. Then, the high-frequency current generated by the positive and negative symmetrical high-frequency square wave voltage consumes the energy of the DC side capacitor. The average value of the high-frequency current is zero. Regardless of whether the rotor position is correct, the average value of the generated current and the average value of the torque are also zero, thereby achieving safe discharge in the case of position sensor failure or no position sensor, and without relying on additional hardware current.

[0011] In a first aspect, the present invention provides an active discharge method for a motor controller, comprising: In response to the active discharge command, if the current bus voltage is greater than the active discharge voltage threshold, the collected AC side current in the three-phase stationary coordinate system will be transformed to obtain the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system. The direct-axis current and quadrature-axis current are low-pass filtered to obtain the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current; The difference signal between the direct-axis fundamental frequency current and the pre-set zero direct-axis current command value, and the difference signal between the quadrature-axis fundamental frequency current and the pre-set zero quadrature-axis current command value are calculated by current closed-loop regulation to obtain the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. The direct-axis fundamental frequency voltage command value is obtained by superimposing the pre-generated positive and negative symmetrical high-frequency square wave voltage signal, and the quadrature-axis fundamental frequency voltage command value is used as the quadrature-axis voltage command value. The direct-axis voltage command value and the quadrature-axis voltage command value are transformed to obtain the voltage command value in the two-phase stationary coordinate system. The voltage command value in the two-phase stationary coordinate system is modulated and calculated, and the corresponding voltage command value is output through the three-phase inverter to act on the motor so that the motor actively discharges. If the collected bus voltage is less than the active discharge voltage threshold, the active discharge is determined to be over and the discharge is terminated.

[0012] Optionally, the active discharge command is issued by the vehicle control unit (VCU).

[0013] Optionally, converting the collected AC current of the motor in the three-phase stationary coordinate system into direct-axis current and quadrature-axis current in the two-phase rotating coordinate system includes: The three-phase currents acquired by the current sensor in the three-phase stationary coordinate system are transformed by Clarke to the α-axis current and β-axis current in the two-phase stationary coordinate system: By performing the Park transformation on the α-axis current and β-axis current in the two-phase stationary coordinate system, the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system are obtained.

[0014] Optionally, the expression for the Clarke transform is: ; in, i α and i β Let represent the α-axis current and β-axis current in a two-phase stationary coordinate system, respectively. i A , i B and i C These represent the AC currents of phases A, B, and C in a three-phase stationary coordinate system, respectively. The expression for the Park transformation is: ; in, i d and i q Let represent the direct-axis current and quadrature-axis current in a two-phase rotating coordinate system, respectively. θ e This indicates the rotor angle of the motor.

[0015] Optionally, the expressions for the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current in the two-phase rotating coordinate system are obtained by low-pass filtering the direct-axis current and the quadrature-axis fundamental frequency current: ; in, i d and i q These represent the direct-axis current and quadrature-axis current in a two-phase rotating coordinate system, respectively, and LPF represents a low-pass filter. i d0 and i q0These represent the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current, respectively. The expressions for the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value are as follows: ; in, u* d0 and u* q0 These represent the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. i d—ref and i q—ref These represent the direct-axis current command value and the quadrature-axis current command value, respectively. ACR represents the current regulator.

[0016] Optionally, the expression for the positive and negative symmetrical high-frequency square wave voltage signal is: ; in, u inj This represents a high-frequency square wave voltage signal. U inj Indicates voltage amplitude. t Indicates time, T inj This indicates the period, where n is a positive integer.

[0017] Optionally, the expressions for the direct-axis voltage command value and the quadrature-axis voltage command value are: ; in, u* d and u* q These represent the direct-axis voltage command value and the quadrature-axis voltage command value, respectively. u inj This represents a high-frequency square wave voltage signal. u* d0 and u* q0 These represent the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively.

[0018] Optionally, the expression for transforming the direct-axis voltage command value and the quadrature-axis voltage command value to obtain the voltage command value in the two-phase stationary coordinate system is as follows: ; in, u* α0 and u* β0 These represent the α-axis voltage command value and the β-axis voltage command value in the two-phase stationary coordinate system, respectively. θ e This indicates the rotor angle of the motor.

[0019] In a second aspect, the present invention provides an active discharge device for a motor controller, comprising: The acquisition module is used to respond to the active discharge command. If the current bus voltage is greater than the active discharge voltage threshold, the acquired AC side current in the three-phase stationary coordinate system is transformed into the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system. A low-pass filter processing module is used to perform low-pass filtering on the direct-axis current and quadrature-axis current to obtain the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current; The current closed-loop regulation module is used to calculate the difference signal between the direct-axis fundamental frequency current and the preset zero direct-axis current command value, and the difference signal between the quadrature-axis fundamental frequency current and the preset zero quadrature-axis current command value through current closed-loop regulation to obtain the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. The first processing module is used to superimpose the direct-axis fundamental frequency voltage command value with a pre-generated positive and negative symmetrical high-frequency square wave voltage signal to obtain the direct-axis voltage command value, and use the quadrature-axis fundamental frequency voltage command value as the quadrature-axis voltage command value; The second processing module is used to transform the direct-axis voltage command value and the quadrature-axis voltage command value to obtain the voltage command value in the two-phase stationary coordinate system, perform modulation calculation on the voltage command value in the two-phase stationary coordinate system, and output the corresponding voltage command value through the three-phase inverter to act on the motor so that the motor actively discharges. The judgment module is used to determine the end of active discharge and terminate the discharge if the collected bus voltage is less than the active discharge voltage threshold.

[0020] Thirdly, the present invention provides a computer-readable storage medium storing computer instructions for causing the computer to execute the motor controller active discharge method.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention performs low-pass filtering on the direct-axis and quadrature-axis currents to obtain direct-axis and quadrature-axis fundamental frequency currents that have been filtered out of high-frequency current. Based on these filtered direct-axis and quadrature-axis fundamental frequency currents, and the direct-axis and quadrature-axis current command values ​​set to zero, closed-loop current regulation calculations are performed to obtain direct-axis and quadrature-axis fundamental frequency voltage command values, respectively. This allows the motor to be controlled to prevent the generation of any fundamental frequency current, thus avoiding motor malfunctions caused by unexpected torque. Furthermore, after pre-processing with low-pass filtering, this invention superimposes the fundamental frequency voltage command value with a pre-generated positive and negative symmetrical high-frequency square wave voltage signal to obtain the direct-axis voltage command value. The high-frequency current generated by the high-frequency square wave voltage then consumes the DC-side capacitor energy. The average high-frequency current is zero and exceeds the motor's response range. Therefore, regardless of whether the rotor position is correct, the average current and average torque are also zero, thereby achieving safe discharge in the event of position sensor failure or absence. Attached Figure Description

[0022] Picture 1 This is a schematic diagram of the motor coordinate system used in the active discharge method of the motor controller according to an embodiment of the present invention; Picture 2 Overall block diagram of the active discharge method for motor controller according to an embodiment of the present invention; Picture 3 for Picture 2 Hardware topology diagram of a three-phase inverter in the diagram; Picture 4 This is a flowchart of the active discharge method for a motor controller according to an embodiment of the present invention. Detailed Implementation

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0025] This embodiment provides a method for active discharge of a motor controller. The active discharge function is used to quickly dissipate the remaining electrical energy stored in the DC filter capacitor on the bus side of the motor controller after the vehicle is powered off, so as to prevent vehicle maintenance personnel from being electrocuted. like Picture 1 The diagram shown is a schematic of the motor coordinate system involved in this embodiment, which includes the relative relationships of the permanent magnet NS poles, the three-phase stationary ABC coordinate system, the two-phase stationary α-β coordinate system, and the two-phase rotating dq coordinate system.

[0026] In this system, the α-axis of the two-phase stationary coordinate system is defined to be in the same direction as the A-axis of the three-phase stationary coordinate system, the d-axis of the two-phase rotating coordinate system (i.e., the direct axis) is in the same direction as the N pole of the permanent magnet, and the q-axis (i.e., the quadrature axis) leads the direct axis by 90°. θ eThe angle between the direct axis and the A-axis is typically obtained using a position sensor connected to the rotor. The direct axis is defined in motor control as being aligned with the direction of the rotor's permanent magnets. Current flowing along this axis only weakens / strengthens the magnetic field and does not generate torque. Therefore, in winding discharge schemes, the d-axis current is controlled to a certain magnitude to achieve discharge. The quadrature axis is the axis that leads the direct axis by 90°. Current flowing along this axis generates motor torque. Therefore, in winding discharge schemes, the current along this axis is controlled to be zero.

[0027] like Picture 2 The figure shown is an overall block diagram of the present invention; in the figure, u* d , u* q The voltage command value is the superimposed high-frequency square wave voltage signal in a two-phase rotating coordinate system. u* α and u* β This represents the voltage command value in a two-phase stationary coordinate system. i A , i B , i C These are the sampled values ​​of the motor current for phases A, B, and C. i α , i β Let α-axis current and β-axis current be defined in a two-phase stationary coordinate system. i d , i q Let be the direct-axis current and quadrature-axis current in a two-phase rotating coordinate system.

[0028] Picture 3 for Picture 2 The hardware topology of the three-phase inverter is described. This topology adopts a general three-phase inverter bridge structure, consisting of a DC-side support capacitor, upper and lower bridge arms for phase A, upper and lower bridge arms for phase B, and upper and lower bridge arms for phase C. The three-phase inverter is connected to the motor junction box via a three-phase power harness.

[0029] like Picture 4 The diagram shown is a flowchart of an active discharge method for a motor controller in this embodiment. U dc This is the current DC bus voltage value. U dc_Throld The active discharge completion voltage threshold is typically below 60V; the method specifically includes: Step S1: In response to the active discharge command issued by the vehicle controller (VCU), if the current bus voltage is greater than the active discharge voltage threshold, the collected AC side current in the three-phase stationary coordinate system is transformed to obtain the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system. Step S1 specifically includes: performing a Clarke transformation on the three-phase currents acquired by the current sensor in the three-phase stationary coordinate system to obtain α-axis and β-axis currents in the two-phase stationary coordinate system. The Clarke transformation, used in motor control, converts voltage or current signals in the two-phase stationary coordinate system to those in the three-phase stationary coordinate system. The Park transformation is then performed on the α-axis and β-axis currents in the two-phase stationary coordinate system to obtain the direct-axis and quadrature-axis currents in the two-phase rotating coordinate system. The Park transformation, also used in motor control, converts voltage or current signals in the two-phase stationary coordinate system to those in the two-phase rotating coordinate system.

[0030] The expression for the Clarke transform is: ; in, i α and i β Let represent the α-axis current and β-axis current in a two-phase stationary coordinate system, respectively. i A , i B and i C These represent the AC currents of phases A, B, and C in a three-phase stationary coordinate system, respectively. The expression for the Park transformation is: ; in, i d and i q Let represent the direct-axis current and quadrature-axis current in a two-phase rotating coordinate system, respectively. θ e This indicates the rotor angle of the motor.

[0031] Step S2: Perform low-pass filtering on the direct-axis current and quadrature-axis current to obtain the direct-axis fundamental frequency current and quadrature-axis fundamental frequency current, expressed as: ; in, i d and i q These represent the direct-axis current and quadrature-axis current in a two-phase rotating coordinate system, respectively. LPF (Low Pass Filter) represents a low-pass filter, which can filter out high-frequency signals from the original signal and retain low-frequency signals and the motor's fundamental frequency signal. i d0 and i q0 These represent the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current, respectively. Step S3: The difference signal between the direct-axis fundamental frequency current and the preset zero direct-axis current command value, and the difference signal between the quadrature-axis fundamental frequency current and the preset zero quadrature-axis current command value are calculated by current closed-loop regulation to obtain the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. The expressions for the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value are as follows: ; in, u* d0 and u* q0 These represent the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. i d—ref and i q—ref These represent the direct-axis current command value and the quadrature-axis current command value, respectively. ACR (Auto Current Regulator): a current regulator used to adjust the motor current so that the actual current matches the commanded current. It is generally in the form of PI (proportional-integral). Step S4: Superimpose the direct-axis fundamental frequency voltage command value with the pre-generated positive and negative symmetrical high-frequency square wave voltage signal to obtain the direct-axis voltage command value, and use the quadrature-axis fundamental frequency voltage command value as the quadrature-axis voltage command value; The expression for the positive and negative symmetrical high-frequency square wave voltage signal is: ; in, u inj This represents a high-frequency square wave voltage signal. U inj Indicates voltage amplitude. t Indicates time, T inj This indicates the period, where n is a positive integer.

[0032] The expressions for the direct-axis voltage command value and the quadrature-axis voltage command value are: ; in, u* d and u* q These represent the direct-axis voltage command value and the quadrature-axis voltage command value, respectively. u inj This represents a high-frequency square wave voltage signal. u* d0 and u* q0 These represent the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively.

[0033] Step S5: Transform the direct-axis voltage command value and the quadrature-axis voltage command value to obtain the voltage command value in the two-phase stationary coordinate system. ; in, u* α0 and u* β0 These represent the α-axis voltage command value and the β-axis voltage command value in the two-phase stationary coordinate system, respectively. θ e This indicates the rotor angle of the motor.

[0034] Furthermore, the voltage command value in the two-phase stationary coordinate system is subjected to PWM (Pulse Width Modulation, which converts the DC signal into a pulse signal with adjustable width to drive the three-phase inverter circuit to generate a voltage pulse with a fixed amplitude and adjustable pulse width) modulation operation, and the corresponding voltage command value is output by the three-phase inverter to act on the motor so that the motor actively discharges. In this embodiment, the active discharge method adjusts the base frequency voltage in the two-phase rotating coordinate system so that the motor does not generate any base frequency current to avoid motor abnormalities caused by unexpected torque, and the high-frequency current generated by the high-frequency square wave voltage signal consumes the energy of the DC-side capacitor. Since the average value of the high-frequency current is zero and its frequency exceeds the mechanical response range of the motor, it does not affect the motor's operation regardless of the rotor position. θ e Whether this is correct or not, the average value of the generated current and the average value of the torque are also zero, thus achieving safe discharge in the event of position sensor failure or absence of position sensor.

[0035] Step S6: If the collected bus voltage is less than the active discharge voltage threshold, the active discharge is determined to be over and the discharge is terminated. The discharge method in this embodiment repeats steps S1 to S5, using base frequency current adjustment and high-frequency voltage superposition to ensure the motor only generates a high-frequency current with an average value of zero, thereby achieving safe discharge in the event of position sensor failure or absence of a position sensor.

[0036] In summary, the discharge method of this embodiment can achieve safe discharge without generating unexpected torque in situations where the motor rotor position analysis is incorrect, such as when the motor position sensor is damaged or malfunctioning, there is no position sensor, or the position sensor zero position is deviated.

[0037] Another embodiment provides an active discharge device for a motor controller, comprising: The acquisition module is used to respond to the active discharge command. If the current bus voltage is greater than the active discharge voltage threshold, the acquired AC side current in the three-phase stationary coordinate system is transformed into the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system. A low-pass filter processing module is used to perform low-pass filtering on the direct-axis current and quadrature-axis current to obtain the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current; The current closed-loop regulation module is used to calculate the difference signal between the direct-axis fundamental frequency current and the preset zero direct-axis current command value, and the difference signal between the quadrature-axis fundamental frequency current and the preset zero quadrature-axis current command value through current closed-loop regulation to obtain the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. The first processing module is used to superimpose the fundamental frequency voltage command value with a pre-generated positive and negative symmetrical high-frequency square wave voltage signal to obtain a direct-axis voltage command value, and use the quadrature-axis fundamental frequency voltage command value as the quadrature-axis voltage command value; The second processing module is used to transform the direct-axis voltage command value and the quadrature-axis voltage command value to obtain the voltage command value in the two-phase stationary coordinate system, perform modulation calculation on the voltage command value in the two-phase stationary coordinate system, and output the corresponding voltage command value through the three-phase inverter to act on the motor so that the motor actively discharges. The judgment module is used to determine the end of active discharge and terminate the discharge if the collected bus voltage is less than the active discharge voltage threshold.

[0038] Another embodiment provides a computer-readable storage medium storing computer instructions for causing the computer to perform the active discharge method of the motor controller according to any one of claims 1-8.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for active discharge of a motor controller, characterized in that, include: In response to the active discharge command, if the current bus voltage is greater than the active discharge voltage threshold, the collected AC side current in the three-phase stationary coordinate system will be transformed to obtain the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system. The direct-axis current and quadrature-axis current are low-pass filtered to obtain the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current; The difference signal between the direct-axis fundamental frequency current and the pre-set zero direct-axis current command value, and the difference signal between the quadrature-axis fundamental frequency current and the pre-set zero quadrature-axis current command value are calculated by current closed-loop regulation to obtain the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. The direct-axis fundamental frequency voltage command value is obtained by superimposing the pre-generated positive and negative symmetrical high-frequency square wave voltage signal, and the quadrature-axis fundamental frequency voltage command value is used as the quadrature-axis voltage command value. The direct-axis voltage command value and the quadrature-axis voltage command value are transformed to obtain the voltage command value in the two-phase stationary coordinate system. The voltage command value in the two-phase stationary coordinate system is modulated and calculated, and the corresponding voltage command value is output through the three-phase inverter to act on the motor so that the motor actively discharges. If the collected bus voltage is less than the active discharge voltage threshold, the active discharge is determined to be over and the discharge is terminated.

2. The active discharge method for a motor controller according to claim 1, characterized in that, The active discharge command is issued by the vehicle control unit (VCU).

3. The active discharge method for a motor controller according to claim 1, characterized in that, The process of converting the collected AC current of the motor in the three-phase stationary coordinate system into the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system includes: The three-phase currents acquired by the current sensor in the three-phase stationary coordinate system are transformed by Clarke to the α-axis current and β-axis current in the two-phase stationary coordinate system: By performing the Park transformation on the α-axis current and β-axis current in the two-phase stationary coordinate system, the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system are obtained.

4. The active discharge method for a motor controller according to claim 3, characterized in that, The expression for the Clarke transform is: ； in, i α and i β Let represent the α-axis current and β-axis current in a two-phase stationary coordinate system, respectively. i A , i B and i C These represent the AC currents of phases A, B, and C in a three-phase stationary coordinate system, respectively. The expression for the Park transformation is: ； in, i d and i q Let represent the direct-axis current and quadrature-axis current in a two-phase rotating coordinate system, respectively. θ e This indicates the rotor angle of the motor.

5. The active discharge method for a motor controller according to claim 1, characterized in that, The expressions for the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current in the two-phase rotating coordinate system are obtained by low-pass filtering the direct-axis current and the quadrature-axis fundamental frequency current: ； in, i d and i q These represent the direct-axis current and quadrature-axis current in a two-phase rotating coordinate system, respectively, and LPF represents a low-pass filter. i d0 and i q0 These represent the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current, respectively. The expressions for the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value are as follows: ； in, u* d0 and u* q0 These represent the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. i d_ref' and i q_ref' These represent the direct-axis current command value and the quadrature-axis current command value, respectively. ACR represents the current regulator.

6. The active discharge method for a motor controller according to claim 1, characterized in that, The expression for the positive and negative symmetrical high-frequency square wave voltage signal is: ； in, u inj This represents a high-frequency square wave voltage signal. U inj Indicates voltage amplitude. t Indicates time, T inj This indicates the period, where n is a positive integer.

7. The active discharge method for a motor controller according to claim 6, characterized in that, The expressions for the direct-axis voltage command value and the quadrature-axis voltage command value are: ； in, u* d and u* q These represent the direct-axis voltage command value and the quadrature-axis voltage command value, respectively. u inj This represents a high-frequency square wave voltage signal. u* d0 and u* q0 These represent the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively.

8. The active discharge method for a motor controller according to claim 7, characterized in that, The expression for the voltage command value in the two-phase stationary coordinate system obtained by transforming the direct-axis voltage command value and the quadrature-axis voltage command value is as follows: ； in, u* α0 and u* β0 These represent the α-axis voltage command value and the β-axis voltage command value in the two-phase stationary coordinate system, respectively. θ e This indicates the rotor angle of the motor.

9. An active discharge device for a motor controller, characterized in that, include: The acquisition module is used to respond to the active discharge command. If the current bus voltage is greater than the active discharge voltage threshold, the acquired AC side current in the three-phase stationary coordinate system is transformed into the direct-axis current and quadrature-axis current in the two-phase rotating coordinate system. A low-pass filter processing module is used to perform low-pass filtering on the direct-axis current and quadrature-axis current to obtain the direct-axis fundamental frequency current and the quadrature-axis fundamental frequency current; The current closed-loop regulation module is used to calculate the difference signal between the direct-axis fundamental frequency current and the preset zero direct-axis current command value, and the difference signal between the quadrature-axis fundamental frequency current and the preset zero quadrature-axis current command value through current closed-loop regulation to obtain the direct-axis fundamental frequency voltage command value and the quadrature-axis fundamental frequency voltage command value, respectively. The first processing module is used to superimpose the direct-axis fundamental frequency voltage command value with a pre-generated positive and negative symmetrical high-frequency square wave voltage signal to obtain the direct-axis voltage command value, and use the quadrature-axis fundamental frequency voltage command value as the quadrature-axis voltage command value; The second processing module is used to transform the direct-axis voltage command value and the quadrature-axis voltage command value to obtain the voltage command value in the two-phase stationary coordinate system, perform modulation calculation on the voltage command value in the two-phase stationary coordinate system, and output the corresponding voltage command value through the three-phase inverter to act on the motor so that the motor actively discharges. The judgment module is used to determine the end of active discharge and terminate the discharge if the collected bus voltage is less than the active discharge voltage threshold.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the motor controller active discharge method according to any one of claims 1-8.

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