A control method for active discharge of a motor controller

Abstract

The application relates to the technical field of motor driving control, and discloses a control method for active discharge of a motor controller, which comprises the following steps: the motor controller receives a control request message based on active discharge; the motor controller enters an active discharge operation mode according to the control request message based on active discharge, carries out active discharge by injecting a high-frequency sinusoidal D-axis current into the motor, and controls the motor controller to complete active discharge when the bus voltage obtained within a preset time range is lower than a safety voltage during the active discharge process; the high-frequency sinusoidal D-axis current discharge can not only solve the torque pulsation problem caused by motor state deviation or position sensor installation error during discharge, but also improve the driving experience of the whole vehicle, so that the stability of the discharge process is improved without relying on a complex position error compensation algorithm and without increasing cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor drive control, more particularly, it relates to a motor controller active discharge control method. BACKGROUND

[0002] In the motor drive control system, the active discharge technology is the core link to ensure the safe operation of the system. When the motor system needs to be shut down or enter standby state, the energy stored in the DC bus capacitor needs to be quickly released through the inverter topology.

[0003] The traditional active discharge method is to discharge through the motor winding, that is, to add D-axis current. This method has fast discharge time, but when there is manufacturing deviation in motor parameters or calibration error in rotor position sensor installation, the discharge current is asymmetrically distributed in the three-phase winding, and the unbalanced current will produce periodic torque ripple, causing mechanical vibration of the motor body, which directly affects the driving experience at the vehicle end.

[0004] Therefore, there is an urgent need for an active discharge control method that can avoid the generation of periodic torque ripple to solve the above technical problems. SUMMARY

[0005] The present application provides a motor controller active discharge control method, which solves the technical problem of periodic torque ripple caused by manufacturing deviation in motor parameters or calibration error in rotor position sensor installation, which causes mechanical vibration of the motor body.

[0006] The present application provides a motor controller active discharge control method, comprising:

[0007] The motor controller receives a control request message based on active discharge;

[0008] The motor controller enters the active discharge operation mode according to the control request message, cuts off the PWM output to stop the original motor drive state, and after a short delay to stabilize, injects high-frequency sinusoidal D-axis current into the motor for active discharge. During the active discharge process, if the bus voltage obtained within the preset time range is lower than the safety voltage, the motor controller is controlled to complete the active discharge.

[0009] Further, the control request message based on active discharge is obtained by the motor controller monitoring the communication interface, hardware signal interface and internal state of the motor controller in real time to trigger the active discharge condition.

[0010] Further, the motor controller receives the control request message triggering the active discharge condition, analyzes the control request message, and enters an active discharge operation mode after obtaining the control request message meeting the charge and discharge condition, wherein the step of obtaining the control request message meeting the charge and discharge condition comprises:

[0011] Filtering invalid active discharge-based control request messages through message integrity, CRC check, timing check, source authentication and logical consistency verification;

[0012] According to the preset priority standard and the source of the active discharge-based control request message, priority judgment is performed, and the active discharge-based control request message is assigned a corresponding priority level, and the priority level includes P0 level, P1 level, P2 level and P3 level.

[0013] Then, the discharge strategy is adaptively adjusted according to the current motor speed, current value, bus voltage, inverter temperature and fault state of the motor controller.

[0014] Finally, redundant confirmation is performed on the key safety signal to exclude false touch behavior caused by sensor failure, communication interference and software exception, and the key safety signal refers to the P0 level control request message.

[0015] Further, the step of actively discharging by injecting high-frequency sinusoidal D-axis current into the motor comprises:

[0016] The motor controller enters an active discharge operation mode according to the control request message, and controls the Q-axis current to be 0 and the D-axis to be a given high-frequency sinusoidal current when the motor controller actively discharges. :

[0017] ;

[0018] By injecting high-frequency sinusoidal D-axis current into the motor, based on the deviation between the rotor angle and the detection angle in the motor controller The Q-axis coupling high-frequency current component can be obtained :

[0019] ;

[0020] Wherein represents the actual Q-axis current, i.e. the Q-axis component in the actual coordinate system; represents the given D-axis current; represents the sinusoidal function; represents the installation deviation angle of the rotor position sensor; represents the angular frequency of the given high-frequency sinusoidal current, i.e. the frequency parameter of the high-frequency sinusoidal D-axis current. represents the amplitude of the given D-axis high-frequency sinusoidal current; represents a time variable.

[0021] Further, the amplitude of the given D-axis high-frequency sinusoidal current is 30% to 50% of the rated current of the motor.

[0022] Further, the high-frequency sinusoidal D-axis current for active discharge is used to raise the angular frequency of the current component coupled on the Q-axis to a frequency band outside the sensitive frequency band of the mechanical system.

[0023] Further, the motor controller monitors the DC bus voltage in real time, and the discharge state is determined when the DC bus voltage drops below a safe voltage, and the discharge is determined to fail and a fault handling process is triggered when the DC bus voltage does not reach the safe voltage within a specified time.

[0024] Further, the safe voltage when the discharge is determined to be completed when the DC bus voltage drops below the safe voltage is 60V, and the specified time when the discharge is determined to fail and the fault handling process is triggered when the DC bus voltage does not reach the safe voltage is 3 seconds.

[0025] Further, the fault handling process includes: self-diagnosing the reason for the discharge failure; recording the discharge failure event and system state information to the memory; sending the discharge failure warning information to the vehicle control system through the vehicle communication network; returning to the un-discharged state.

[0026] The application provides a computer storage medium, comprising a memory and one or more processors, the memory stores executable code, and the one or more processors execute the executable code to implement the control method of the motor controller active discharge according to any one of claims 1-9.

[0027] The application has the beneficial effect that: through the high-frequency sinusoidal D-axis current discharge, not only the torque pulsation problem caused by the motor state deviation or the position sensor installation error during discharge can be solved, the driving experience of the vehicle is improved, and the stability of the discharge process is improved without relying on complex position error compensation algorithm and without increasing cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flowchart for the active discharge of the application.

[0029] Figure 2 The DQ-axis current component diagram when the rotor position has an error and the D-axis current discharge is requested.

[0030] Figure 3Fig. 1 is a schematic diagram of a given D-axis high-frequency sinusoidal current when discharging a motor winding according to the present application. DETAILED DESCRIPTION

[0031] The subject matter described herein will now be discussed with reference to example implementations. It should be understood that discussions of these implementations are intended to serve as examples of the subject matter described herein and should not be construed as limiting the subject matter described herein to these example implementations. Various examples can omit, substitute, or add various procedures or components as appropriate, and the modifications should be interpreted as falling within the scope of the claims. In addition, a variety of changes could be made to the examples described herein without departing from the scope of the subject matter described herein. For instance, the elements or acts of any of the examples described herein could be performed in a variety of orders not otherwise explicitly discussed or implied.

[0032] A method for controlling active discharge of a motor controller is disclosed in at least one embodiment of the present application, as shown in Figure 1 including:

[0033] Step 1, the motor controller receives a control request message based on active discharge;

[0034] Step 1.1, obtain a control request based on active discharge;

[0035] The control request message based on active discharge is obtained by real-time monitoring of the communication interface, hardware signal interface and internal state of the motor controller to obtain the control request message triggering the active discharge condition, including:

[0036] Communication interface acquisition:

[0037] The motor controller receives instructions from the vehicle control unit (VCU), battery management system (BMS) or vehicle diagnostic system through the vehicle communication network (such as CAN bus, LIN bus or FlexRay, etc.). The communication module of the motor controller continuously monitors the information on the bus, and identifies the instructions related to active discharge according to the preset communication protocol and message ID. For example:

[0038] Vehicle power-off message sent by VCU (usually contains a specific control byte, such as 0xA5 indicating a request for active discharge);

[0039] Battery protection message sent by BMS (when the battery system detects an anomaly);

[0040] Service request sent by diagnostic equipment through diagnostic protocol (such as UDS).

[0041] In addition to the communication interface, the motor controller also directly monitors the key safety signals through a dedicated hardware interface, i.e. hardware signal acquisition, including:

[0042] Collision sensor signal: Directly connected to the motor controller through a high-priority hardware interrupt line, triggers the discharge procedure immediately when a collision is detected;

[0043] Emergency stop signal: Monitors the emergency stop button state through a dedicated safety input port;

[0044] Power management unit signal: Monitors the key switch position or control signals of the power management unit.

[0045] The motor controller itself also monitors the internal system status and actively triggers the discharge procedure when serious faults are detected, including:

[0046] Detection of serious overcurrent, overvoltage or overtemperature faults;

[0047] System software detects an unrecoverable control anomaly;

[0048] Safety handling procedure after watchdog circuit reset.

[0049] Step 1.2, analyze the control request based on active discharge;

[0050] After the motor controller receives the control request message that triggers the active discharge condition, it performs control request message analysis. After obtaining a control request message that meets the charge and discharge conditions, the motor controller enters the active discharge operation mode. The step of obtaining a control request message that meets the charge and discharge conditions specifically includes:

[0051] Signal validity check, verify the integrity and validity of the signal, prevent false triggering, specific check items include:

[0052] Communication message integrity verification: For instructions received through CAN bus, etc., check the data length field, frame format, whether it conforms to the protocol specification, whether there is bus error or frame loss;

[0053] CRC check code verification: Perform cyclic redundancy check on critical safety instructions to ensure that data has not been corrupted or tampered with during transmission;

[0054] Signal timing check: Verify whether the arrival time of the signal is within the expected range to prevent long-delay invalid instructions from being executed;

[0055] Signal source identity verification: Confirm whether the node ID sending the instruction is an authorized device to prevent false instructions from being sent by illegal devices;

[0056] Signal logic consistency check: Verify whether the current received instruction is logically consistent with the system historical state, such as not receiving a run instruction in the motor stopped state.

[0057] Signal priority judgment: Different sources of discharge requests have different priorities, and the system adopts a hierarchical response mechanism:

[0058] Highest priority (P0 level, critical safety signals): Collision sensor signals, airbag controller signals, and other hardware signals directly related to personal safety, with a response time <5ms and unconditional execution;

[0059] High priority (P1 level): Battery management system emergency power-off instructions, vehicle controller fault protection instructions, and other communication instructions related to device safety, with a response time <20ms;

[0060] Medium priority (P2 level): Vehicle controller normal power-off instructions, diagnostic device maintenance instructions, and other instructions in normal operating state, with a response time <100ms;

[0061] Low priority (P3 level): Maintenance discharge triggered by timing tasks, test discharge triggered manually by users, etc., which can be interrupted by higher priority instructions. When multiple instructions of different priorities arrive at the same time, the system responds to high priority instructions first, and low priority instructions enter the waiting queue or are discarded directly.

[0062] State condition judgment: Determine the specific discharge strategy and parameters based on the current motor drive control system state:

[0063] Motor speed state judgment: When the motor speed >50rpm, the brake stop process needs to be executed first, and the active discharge is started after the speed drops below 10rpm; When the speed is between 10-50rpm, the discharge can be started directly but the discharge current amplitude needs to be appropriately reduced; When the speed <10rpm, the discharge can be executed according to standard parameters;

[0064] Current state evaluation: Check the current three-phase current effective value. If the current >20% of the motor rated current, it means that the motor is still in the driving state, and the discharge needs to be started after the current drops to a safe range;

[0065] DC bus voltage evaluation: Check if the current DC bus voltage is within the normal range (usually 300-850V). If the voltage is too low (<300V), there is no need to discharge, and if the voltage is too high (>850V), a larger discharge current needs to be used;

[0066] Inverter temperature monitoring: Check the IGBT module temperature. If the temperature >85°C, the discharge interval time needs to be appropriately extended or the discharge current needs to be reduced to prevent overheating protection;

[0067] System fault state check: If a hardware fault of the inverter, a fault of the current sensor, or a fault of the position sensor is detected, a backup discharge strategy or discharge inhibition is used to prevent secondary damage.

[0068] For critical safety signals, a redundant design is adopted, that is, multiple independent signal paths and detection channels are set in the system to prevent single-point failure from causing safety function failure. The specific implementation includes: double-channel signal comparison (such as two independent collision sensor signals triggering simultaneously to execute discharge), signal integrity verification (verifying the correctness of the communication message through CRC check code), time window confirmation (the signal needs to be continuously effective within the preset time window to be identified as a real instruction); preventing false triggering or missed triggering due to sensor failure, communication interference or software anomaly, ensuring that the active discharge function can be reliably executed when needed and never misoperated when not needed.

[0069] When the motor controller receives any of the above instructions and passes the validity verification, it immediately enters the active discharge state.

[0070] Step 2, the motor controller enters the active discharge operation mode according to the active discharge-based control request message, cuts off the PWM output to stop the original motor driving state, stabilizes for a short delay, and then actively discharges by injecting high-frequency sinusoidal D-axis current into the motor. During the active discharge process, if the bus voltage obtained within the preset time range is lower than the safety voltage, the motor controller actively discharges is completed.

[0071] Step 2.1, inject high-frequency sinusoidal D-axis current;

[0072] When there is an installation deviation of the rotor position sensor, a fixed deviation exists between the detected rotor angle and the actual angle When the traditional discharge method uses constant D-axis current discharge, this deviation will cause the actual control coordinate system and the ideal DQ coordinate system not to coincide, and the current decomposed to the actual Q-axis is:

[0073] ;

[0074] where represents the actual Q-axis current, i.e., the Q-axis component in the actual coordinate system; represents the given D-axis current, i.e., the D-axis current expected to be output by the controller; represents the sine function; represents the installation deviation angle of the rotor position sensor, i.e., the difference between the detected rotor angle and the actual angle.

[0075] In the ideal coordinate system, the given Q-axis current should be zero (no torque is needed during discharge), but due to the existence of the angle error , an unexpected Q-axis current component is actually generated. This Q-axis component will generate an unexpected torque, causing torque pulsation during the discharge process of the motor.

[0076] Similarly, the actual D-axis current will also deviate from the given value , which is related by:

[0077]

[0078] where represents the actual D-axis current, i.e. the D-axis component in the actual coordinate system; represents the given D-axis current, i.e. the D-axis current that the controller expects to output; represents the cosine function; represents the installation deviation angle of the rotor position sensor.

[0079] As Figure 2 shown in the figure, which is a schematic diagram of DQ-axis current components when the rotor position has an error and the D-axis current is discharged, where d-q axis is the ideal DQ coordinate system, d'-q' axis is the actual coordinate system with error , the given pure D-axis current in the ideal DQ coordinate system will be decomposed into D-axis component and Q-axis component , so that the Q-axis current generates torque pulsation, so a high-frequency sinusoidal D-axis current is used for discharge, i.e.

[0080]

[0081] where represents the given D-axis current; represents the amplitude of the given D-axis high-frequency sinusoidal current; represents the sine function; represents the angular frequency of the given high-frequency sinusoidal current; represents the time variable;

[0082] As Figure 3 shown in the figure, which is a schematic diagram of the given D-axis high-frequency sinusoidal current when discharging through the motor winding, showing the waveform characteristics of the high-frequency sinusoidal current.

[0083] In practical applications, the current amplitude is usually selected to be 30% to 50% of the rated current of the motor, considering the balance between discharge efficiency and system safety. The angular frequency needs to be higher than the mechanical system response bandwidth, usually selected in the range of 100 to 500 Hz. The mechanical system response bandwidth refers to the frequency range within which the mechanical system can effectively respond to input changes. For a typical electric vehicle drive system, the mechanical response bandwidth is usually below 10 to 30 Hz.

[0084] By injecting high-frequency sinusoidal D-axis current into the motor, the rotor angle deviation in the motor controller is based on the detection angle The Q-axis coupling high-frequency current component can be obtained :

[0085] ;

[0086] wherein represents the actual Q-axis current, i.e. the Q-axis component in the actual coordinate system; represents the given D-axis current; represents the sinusoidal function; represents the installation deviation angle of the rotor position sensor; represents the angular frequency of the given high-frequency sinusoidal current, i.e. the frequency parameter of the high-frequency sinusoidal D-axis current; represents the time variable.

[0087] Due to the existence of the angle deviation , the high-frequency sinusoidal current that should have been completely acting on the D-axis will generate a coupling component on the Q-axis, if the angle deviation is 5°, then about 8.7% of the D-axis current ( ) will be coupled to the Q-axis;

[0088] The Q-axis coupling current has a high-frequency characteristic, and its angular frequency is the same as that of the injected D-axis current , unlike the constant Q-axis component generated by the traditional constant D-axis current method, this high-frequency Q-axis current will generate a high-frequency electromagnetic torque component.

[0089] The high-frequency electromagnetic torque acts on the rotor through the air gap, but since the rotor and the entire transmission system have mechanical inertia, when the torque pulsation angular frequency is much higher than the inherent angular frequency of the mechanical system, the actual angular velocity and angular displacement of the rotor cannot follow the high-frequency torque changes, and the mechanical system behaves as a low-pass filter, with a cutoff frequency usually in the range of 10 to 30 Hz.

[0090] When a high-frequency sinusoidal current corresponding to a frequency of 100 to 500 Hz is injected, the generated torque pulsation angular frequency is far beyond the response bandwidth of the mechanical system, so the actual torque experienced by the rotor is close to the average value of the high-frequency torque, and since the average value of the sinusoidal function in a complete cycle is zero, the average effect of the high-frequency torque pulsation tends to zero, thereby reducing the vibration transmitted to the shaft and the vehicle body.

[0091] In contrast, the Q-axis current component generated by the traditional constant D-axis current discharge method is a constant value, which will result in a low-frequency or constant torque deviation, completely within the response bandwidth of the mechanical system, so the torque pulsation is obvious and the vibration is strong.

[0092] In addition to the low-pass filtering characteristics of the mechanical system, the high-frequency sinusoidal D-axis current discharge method also effectively avoids the problem of low-frequency error amplification. When using constant D-axis current for discharge, the Q-axis current component caused by angle deviation is a low-frequency component, and its corresponding frequency usually falls within the sensitive frequency band of the mechanical system (10-30 Hz). This low-frequency disturbance can resonate with the natural angular frequency of the mechanical system, causing torque pulsation to be amplified and further exacerbating periodic vibration.

[0093] However, with high-frequency sinusoidal D-axis current, the angular frequency of the coupled current component on the Q-axis is raised to a range outside the sensitive frequency band of the mechanical system (100-500 Hz), effectively avoiding the resonance region of the mechanical system, thereby suppressing low-frequency torque pulsation.

[0094] In the present application, the average discharge power of the high-frequency sinusoidal D-axis current discharge method is comparable to that of constant D-axis current, so it does not affect the discharge speed, while avoiding the problem of torque pulsation.

[0095] Step 2.2, the motor controller monitors the DC bus voltage in real time to determine the discharge state;

[0096] The motor controller monitors the DC bus voltage in real time. When the DC bus voltage drops below the safe voltage (usually 60V), it is determined that the discharge is complete, and the PWM output is stopped. The system enters a low-power sleep state.

[0097] The discharge process must be completed within 3 seconds. If it exceeds the time limit, it is determined that the discharge has failed, and the system will trigger a fault handling process.

[0098] The fault handling process includes:

[0099] Discharge failure diagnosis: the system first performs self-diagnosis on the reasons for discharge failure, including detecting the motor winding connection state, inverter power device state, and voltage sensor working state;

[0100] Fault information recording: record the discharge failure event, DC bus voltage value, current value and system state information at the time of failure to the non-volatile memory of the controller, for subsequent fault analysis;

[0101] Fault information reporting: send discharge failure warning information to the vehicle controller and battery management system through the vehicle communication network (such as CAN bus), so that the vehicle system understands the current high-voltage system state;

[0102] Return to the un-discharged state: the system returns to the un-discharged state, waiting for the next discharge command or maintenance personnel's processing.

[0103] A computer storage medium comprises a memory and one or more processors, the memory stores executable code, and the one or more processors execute the executable code to implement the control method of the motor controller active discharge of any one of claims 1-9.

[0104] Here, the application provides an implementation example:

[0105] A new energy automobile Co., Ltd. applied the motor controller active discharge method of the application to its flagship electric SUV model A. The vehicle model adopts 800V high voltage platform architecture, equipped with high performance permanent magnet synchronous motor drive system, while ensuring the driving performance, higher requirements are put forward for system safety.

[0106] The electric drive system of model A adopts single motor rear drive layout, and the main technical parameters are as follows:

[0107] Battery system: ternary lithium battery pack, nominal voltage 800V, capacity 100kWh;

[0108] Motor type: permanent magnet synchronous motor (PMSM), surface mount (SPMSM);

[0109] Motor controller: self-developed MCU-H800 controller based on TI TMS320F28388D dual-core DSP platform;

[0110] Inverter: silicon carbide power device, switching frequency 20kHz;

[0111] Cooling system: water cooling system, controller and motor share cooling loop.

[0112] In the following three typical scenarios, the system will trigger the active discharge process:

[0113] Normal parking scenario: after the driver stops the vehicle and presses the power button to turn off the vehicle, the VCU sends the power-off command, and the motor controller enters the active discharge process after receiving the command;

[0114] Emergency safety scenario: when the vehicle is in collision, the airbag control unit triggers the high voltage cut-off signal, and sends the emergency power-off command to each high voltage component through the CAN bus, and the motor controller immediately executes the active discharge;

[0115] Maintenance scenario: maintenance personnel send specific commands through diagnostic equipment to make the vehicle enter maintenance mode, at which time the motor controller executes active discharge to ensure maintenance safety.

[0116] The main parameter table of the system is shown in Table 1:

[0117] Table 1: Main parameter table of the system

[0118]

[0119] The main parameters of the torque ripple comparison data system under different position sensor biases are shown in Table 2:

[0120] Table 2: Torque ripple comparison data under different position sensor biases

[0121]

[0122] The high-frequency sinusoidal current parameter selection and effect comparison are shown in Table 3:

[0123] Table 3: High-frequency sinusoidal current parameter selection and effect comparison

[0124]

[0125] The discharge time and voltage drop relationship data are shown in Table 4:

[0126] Table 4: Discharge time and voltage drop relationship data

[0127]

[0128] The comparison results of different discharge methods are shown in Table 5:

[0129] Table 5: Comparison results of different discharge methods

[0130]

[0131] The controller hardware configuration is:

[0132] The MCU-H800 controller uses TI TMS320F28388D dual-core DSP as the main control chip, and its hardware configuration is as follows:

[0133] CPU1: main control core, responsible for current loop, speed loop control and active discharge algorithm execution;

[0134] CPU2: monitoring core, responsible for communication, fault diagnosis and safety monitoring;

[0135] Sampling frequency: 20 kHz (synchronized with PWM);

[0136] ADC resolution: 12 bits;

[0137] Current sampling: three-phase current sampling, Hall current sensor;

[0138] Voltage sampling: DC bus voltage sampling, precision resistance voltage dividing network;

[0139] Position sensor: resolver, accuracy ±0.1°.

[0140] The selection of discharge current amplitude and frequency needs to consider the following factors comprehensively:

[0141] Current amplitude selection:

[0142] Discharge time requirement: According to the data in Table 4, a current amplitude of 150A can complete discharge within 2.7 seconds, meeting the national standard requirements;

[0143] Current stress consideration: The current amplitude should not be too large to avoid excessive stress on power devices;

[0144] Frequency selection:

[0145] Mechanical system response bandwidth: The mechanical system response bandwidth of vehicle A is about 25Hz;

[0146] Optimal frequency selection: It should be at least 10 times higher than the mechanical response bandwidth, i.e. above 250Hz;

[0147] According to the data in Table 3, 300Hz is the best frequency selection for comprehensive effect.

[0148] 10 sets of experimental data on vehicle A were conducted under the test conditions of ambient temperature 25℃ and initial DC bus voltage 800V, as shown in Table 6:

[0149] Table 6: 10 sets of experimental data on vehicle A under the test conditions of ambient temperature 25℃ and initial DC bus voltage 800V

[0150]

[0151] Discharge performance under different temperature conditions is shown in Table 7:

[0152] Table 7: Discharge performance under different temperature conditions

[0153]

[0154] Through frequency spectrum analysis of the vibration during vehicle discharge, the following results are obtained:

[0155] Traditional constant D-axis current discharge:

[0156] Main vibration frequency: within 0-30Hz range;

[0157] Vibration amplitude: 1.8 to 1.9mm / s²;

[0158] Human perception: obvious perceptible vibration.

[0159] High-frequency sinusoidal D-axis current discharge:

[0160] Main vibration frequency: 300 Hz (higher than the human perception sensitive area);

[0161] Vibration amplitude: 0.08-0.10 mm / s²;

[0162] Human perception: almost imperceptible.

[0163] Vibration spectrum analysis shows that the high-frequency sinusoidal D-axis current discharge method shifts the vibration frequency to the high-frequency area that is not sensitive to the human body, while reducing the vibration amplitude and improving the passenger comfort.

[0164] A new energy automobile Co., Ltd. successfully applied the high-frequency sinusoidal D-axis current active discharge method on the A electric SUV, and achieved the following technical effects:

[0165] The discharge time meets the national standard requirements, and the average discharge to the safe voltage is completed within 2.7 seconds;

[0166] The torque ripple peak value is reduced by 86.5% compared with the traditional method, significantly improving the comfort of the driver and passengers;

[0167] The system vibration amplitude is reduced by 95%, and the vibration frequency is shifted to the human body insensitive area;

[0168] No additional hardware is needed, and it can be realized through software algorithm upgrade, with obvious cost advantage;

[0169] It can work stably in a wide temperature range of-20°C to 60°C, with strong adaptability.

[0170] The above describes the embodiments of the present application, but the embodiments are not limited to the specific implementation described above, which is only illustrative and not limiting. Those skilled in the art can make more forms of equivalent embodiments under the inspiration of the embodiments, which are all within the protection scope of the embodiments.

Claims

1. A control method of active discharge of a motor controller, characterized by, The application relates to a motor controller and a method for controlling the motor controller. The motor controller receives a control request message based on active discharge; The motor controller parses the received control request message, filters invalid control request messages through message integrity, CRC check, timing check, source authentication and logic consistency verification, and then performs priority judgment according to preset priority standards and the source of the control request message to assign corresponding priority levels, wherein the priority levels include P0 level, P1 level, P2 level and P3 level; then the discharge strategy is adaptively adjusted according to the current motor speed, current value, bus voltage, inverter temperature and fault state of the motor controller; finally, the key safety signal of the P0 level is subjected to redundant confirmation to exclude false touch behaviors caused by sensor failure, communication interference and software exception; and after the control request message meeting the charging and discharging conditions is obtained, the active discharge operation mode is entered; When the discharge strategy is adaptively adjusted according to the current motor speed of the motor controller, if the motor speed is greater than 50 rpm, the brake parking process is first performed, the motor speed is reduced to below 10 rpm, and then the active discharge is started; if the motor speed is between 10 rpm and 50 rpm, the discharge is directly started but the discharge current amplitude is reduced; and if the motor speed is less than 10 rpm, the discharge is performed according to standard parameters; After the motor controller enters the active discharge operation mode, the PWM output is cut off to stop the original motor driving state, and after a short time delay for stabilization, high-frequency sinusoidal D-axis current is injected into the motor for active discharge; the frequency of the high-frequency sinusoidal D-axis current is 100-500 Hz, which is 10-30 Hz higher than the mechanical system response bandwidth of the electric vehicle driving system; and the amplitude of the high-frequency sinusoidal D-axis current is 30%-50% of the rated current of the motor, so that the torque ripple angle frequency generated by the high-frequency current component coupled out of the Q axis is far higher than the mechanical system response bandwidth, thereby making the actual torque felt by the rotor close to the average value of the high-frequency torque. In the active discharge process, if the bus voltage obtained within a preset time range is lower than a safety voltage, the motor controller is controlled to complete the active discharge.

2. The method of claim 1, wherein the method further comprises: The control request message based on active discharge is obtained by the motor controller in real time monitoring of a communication interface, a hardware signal interface and internal states of the motor controller.

3. The method of claim 1, wherein the method further comprises: The step of injecting high-frequency sinusoidal D-axis current into the motor for active discharge includes the following steps: The motor controller enters an active discharge operation mode according to the control request message, and when the motor controller is in active discharge, the Q-axis current is controlled to be 0, and the D-axis is given a high-frequency sinusoidal current : By injecting high frequency sinusoidal D-axis current into the motor, based on the rotor angle and detected angle deviation in the motor controller The Q-axis coupling can get high frequency current component out : wherein represents the actual Q-axis current, i.e. the Q-axis component in the actual coordinate system; represents the given D-axis current; sin denotes the sine function; represents the installation deviation angle of the rotor position sensor; W represents the angular frequency of the given high-frequency sinusoidal current, i.e. the frequency parameter of the high-frequency sinusoidal D-axis current; A represents the amplitude of the given D-axis high-frequency sinusoidal current; t represents the time variable.

4. The method of claim 1, wherein the method further comprises: After the high-frequency sinusoidal D-axis current is injected into the motor for active discharge, the angular frequency of the current component coupled on the Q axis is lifted out of the corresponding mechanical system sensitive frequency band.

5. The method of claim 1, wherein the method further comprises: The motor controller monitors the DC bus voltage in real time, and the discharge state is determined as follows: when the DC bus voltage is reduced to below a safety voltage, the discharge is determined to be completed; and when the DC bus voltage exceeds a safety voltage for a specified time, the discharge is determined to fail and a fault handling process is triggered.

6. The method of claim 5, wherein the method further comprises: The safety voltage when the discharge is determined to be completed is 60 V, and the specified time when the discharge is determined to fail and the fault handling process is triggered is 3 seconds.

7. The method of claim 6, wherein the method further comprises: The fault processing flow comprises: self-diagnosis of the discharge failure cause; recording of the discharge failure event and system state information into a memory; sending of a discharge failure warning message to a vehicle control system through a vehicle-mounted communication network; and returning to an un-discharged state.

8. A computer storage medium, characterized in that The memory stores executable code, and the one or more processors execute the executable code to implement the control method for active discharge of the motor controller according to any one of claims 1 to 7.

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