A method and system for controlling an electric machine

Abstract

The application relates to a motor control method and system, the method comprising: establishing a mapping relationship table of torque and load; obtaining a real-time load, and searching the mapping relationship table according to the real-time load to obtain corresponding torque; obtaining a D-axis current corresponding to an open-loop coordinate system according to the torque and a given power angle; obtaining an actual position angle of a motor rotor according to the power angle and an open-loop angle, and determining a ball screw stroke according to the actual position angle; and controlling the motor according to the ball screw stroke and the D-axis current. The scheme can realize high matching degree between the D-axis current and the actual system load to avoid damage of devices under step-out control, and meanwhile, the accuracy of ball screw stroke calculation is improved.

Description

Technical Field

[0001] This invention relates to the field of vehicles, and more specifically to a motor control method and system. Background Technology

[0002] Current and frequency control (I / F control) of motors is a commonly used open-loop control method. During control, a preset current value and a preset angle are given, achieving closed-loop current control and open-loop angle control. There are two strategies for selecting the I / F current: one is to use the Q-axis current Iq (Id = 0) for control, and the other is to use the D-axis current Id (Iq = 0) for control.

[0003] For an I / F control strategy with a given D-axis current Id (Iq = 0), to ensure that the open-loop drive does not lose synchronization, a D-axis current Id is assigned based on experimental experience to meet the torque requirements during the drive process. When the load changes, the actual D / Q coordinate system will shift angularly from the given D / Q coordinate system, causing the given D-axis current Id to generate an Iq component in the actual coordinate system. This enables the motor to have the torque capacity to carry the load, supporting the realization of open-loop I / F drive.

[0004] However, the above solution has the following problems: 1. The selection of the D-axis current Id is unreasonable: Selecting it based on empirical values, if too small, will result in insufficient torque components, unable to withstand the load, leading to loss of synchronization; if too large, will cause the controller / motor temperature to rise too quickly, leading to the risk of hardware failure. 2. Incorrect calculation of ball screw travel: The upper-level control of EHB / EMB relies on the calculation of ball screw travel, which in turn depends on the actual position of the motor rotor. When I / F drive control is used, due to the given position angle, the actual rotor position will deviate from the given angle to varying degrees depending on the load, affecting the final calculation result of the travel. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a motor control method and system that can improve the calculation accuracy of D-axis current and actual position of motor rotor.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A motor control method and system, comprising: Establish a mapping table between torque and load; Obtain the real-time load, and look up the corresponding torque in the mapping table based on the real-time load; Based on the torque and the given power angle, the D-axis current corresponding to the open-loop coordinate system is obtained; The actual position angle of the motor rotor is obtained based on the power angle and the open-loop angle, and the ball screw stroke is determined based on the actual position angle. The motor is controlled based on the ball screw travel and the D-axis current.

[0007] Based on the above technical solution, the present invention can be further improved as follows.

[0008] Furthermore, establishing the mapping table between torque and load includes: Perform closed-loop speed control on the motor and record the estimated torque curve and load curve of the motor; A mapping table between load and torque is established based on the estimated torque curve of the motor and the load curve.

[0009] Furthermore, based on the torque and the given power angle, the D-axis current corresponding to the open-loop coordinate system is obtained, including: The Q-axis current in the open-loop coordinate system is obtained based on the torque and torque equation. The required D-axis current is obtained based on the Q-axis current and the given power angle.

[0010] Furthermore, obtaining the Q-axis current in the open-loop coordinate system based on the torque and torque equation includes: According to the torque equation Thus, the Q-axis current in the open-loop coordinate system is obtained; in, This refers to the motor torque. This represents the number of pole pairs of the motor. For the rotor flux of the motor, For the D-axis inductance of the motor, For the Q-axis inductance of the motor, This represents the D-axis current.

[0011] Furthermore, obtaining the required D-axis current based on the Q-axis current and the given power angle includes: According to trigonometric functions To obtain the required D-axis current; in, This is the Q-axis current. Given the angle of attack.

[0012] Further, the actual position angle of the motor rotor is obtained based on the power angle and open-loop angle, and the ball screw stroke is determined based on the actual position angle, including: according to Calculate the actual position angle of the motor rotor; in, This refers to the actual position angle. This is the open-loop angle.

[0013] This application also provides a motor control system, including: a relationship construction module, a data acquisition module, a data processing module, and a control module; The relationship building module is used to establish and store a mapping relationship table between torque and load; The data acquisition module is used to acquire real-time load signals, given power angles, open-loop angles, and to look up the corresponding torque based on the real-time load. The data processing module is used to obtain the D-axis current corresponding to the open-loop coordinate system based on the torque and the given power angle, obtain the actual position angle of the motor rotor based on the power angle and the open-loop angle, and determine the ball screw stroke based on the actual position angle. The control module is used to control the motor according to the ball screw stroke and the D-axis current.

[0014] Furthermore, the control module is also used for closed-loop speed control of the motor; The relationship building module is also used to record the estimated torque curve and load curve of the motor, and to establish a mapping relationship table between load and torque based on the estimated torque curve and the load curve.

[0015] Furthermore, the data processing module is also used to obtain the Q-axis current in the open-loop coordinate system based on the torque and the torque equation, and to obtain the required D-axis current based on the Q-axis current and the given power angle.

[0016] Furthermore, the data processing module is also used for: According to the torque equation Obtain the Q-axis current in the open-loop coordinate system. And according to trigonometric functions Obtain the required D-axis current.

[0017] The advantages of adopting the above scheme are: by using the force sensor in EHB / EMB, the system load status can be obtained, and the D-axis current and the actual position of the motor rotor required for I / F sensorless control can be calculated based on the load. This can achieve a high degree of matching between the D-axis current and the actual system load to avoid damage to the device under out-of-step control, while also improving the accuracy of ball screw stroke calculation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the open-loop coordinate system of the present invention.

[0019] Figure 2 This is a schematic diagram of the motor control method of the present invention.

[0020] Figure 3 This is a schematic diagram of the motor control system of the present invention.

[0021] Figure 4 This is a schematic diagram of the vehicle of the present invention. Detailed Implementation

[0022] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0023] This application can be used in sensorless control systems for EHB / EMB motors. Motor I / F control (current-frequency ratio control) is a common strategy in sensorless control for low-speed applications. However, this strategy encounters some problems in online control applications. Especially under different motor loads, conditions such as pressure holding and clamping force maintenance can lead to problems such as inappropriate I / F current causing motor step loss, excessive temperature rise damaging components, and incorrect ball screw stroke calculation. Therefore, in the above application scenarios, it is particularly important to avoid the systemic impact of load on sensorless I / F control.

[0024] Figure 1 This is a schematic diagram of the open-loop coordinate system of the present invention, as shown below. Figure 1 In open-loop I / F drive control of a motor, the algorithm references the open-loop coordinate system, and the D-axis current Id is also controlled within this coordinate system. If the Q-axis current Iq is zero, no torque is applied to the motor rotor. When the load increases, the torque acting on the motor rotor is too small, and the actual rotor angle cannot follow the open-loop angle. Therefore, the actual D / Q coordinate system will have an angular offset relative to the open-loop coordinate system. After this offset, the D-axis current Id of the open-loop coordinate axis will map onto the actual coordinate axis to represent the true D and Q current components. The current component on the Q-axis will then generate torque to resist the load. The larger the coordinate system offset angle, the larger the Q-axis current component in the actual coordinate system, the greater the motor torque, and the stronger the load-carrying capacity. The coordinate system offset angle can be considered as the power angle. Therefore, the traditional solution using D-axis current for I / F control is essentially a process of power angle adaptation based on the load.

[0025] Example 1 Figure 2 This is a schematic diagram of the motor control method of the present invention, as shown below. Figure 1 and 2 This application provides a motor control method and system, the method comprising: Establish a mapping table between torque and load; Obtain the real-time load and look up the corresponding torque in the mapping table based on the real-time load. Based on the torque and the given power angle, the D-axis current corresponding to the open-loop coordinate system is obtained; The actual position angle of the motor rotor is obtained based on the power angle and the open-loop angle, and the ball screw stroke is determined based on the actual position angle. The motor is controlled based on the ball screw travel and the D-axis current.

[0026] Optionally, in the embodiments of this application, by using the force sensor in EHB / EMB to obtain the system load state, and calculating the D-axis current and the actual position of the motor rotor required for I / F sensorless control based on the load, a high degree of matching between the D-axis current and the actual system load can be achieved to avoid device damage under out-of-step control, while improving the accuracy of ball screw stroke calculation.

[0027] Based on the above technical solution, the present invention can be further improved as follows.

[0028] Furthermore, a mapping table between torque and load is established, including: Perform closed-loop speed control on the motor and record the estimated torque curve and load curve of the motor; Establish a mapping table between load and torque based on the estimated torque curve and load curve of the motor.

[0029] Optionally, establishing a mapping table between torque and load is a prerequisite for this application. In this embodiment, the load is represented by pressure / clamping force. Specifically, the current motor load status of the wire-controlled actuator system, i.e., pressure / clamping force, can be obtained in real time through the hydraulic sensor on the EHB and the clamping force sensor on the EMB.

[0030] Before implementing I / F control, the pressure / clamping force to torque mapping table needs to be calibrated. The calibration method is as follows: Use the motor position sensor signal to perform closed-loop control of the motor speed, rotating the motor forward at a low speed (e.g., 10 rpm), and record the estimated torque curve and pressure / clamping force curve of the motor during this process. Finally, use the above two curves to establish a mapping table and write it into the software.

[0031] Based on the above steps, the load torque at the motor end under different system loads can be obtained by calibrating the mapping relationship.

[0032] Furthermore, based on the torque and the given power angle, the D-axis current corresponding to the open-loop coordinate system is obtained, including: The Q-axis current in the open-loop coordinate system is obtained based on the torque and the torque equation. The required D-axis current is obtained based on the Q-axis current and the given power angle.

[0033] Furthermore, the Q-axis current in the open-loop coordinate system is obtained based on the torque and the torque equation, including: According to the torque equation Thus, the Q-axis current in the open-loop coordinate system is obtained; in, This refers to the motor torque. This represents the number of pole pairs of the motor. For the rotor flux of the motor, For the D-axis inductance of the motor, For the Q-axis inductance of the motor, This represents the D-axis current.

[0034] Alternatively, the actual required Q-axis current to counteract this load can be obtained using the electromagnetic torque formula. (Right now Figure 1 (The actual Q-axis current component in the data).

[0035] Furthermore, the required D-axis current is obtained based on the Q-axis current and the given power angle, including: According to trigonometric functions To obtain the required D-axis current; in, This is the Q-axis current. Given the angle of attack.

[0036] Optionally, different operating power angle commands can be set according to different load conditions. These commands contain different given power angles. Then, based on the Q-axis current Iq and power angle required by the actual conditions, the D-axis current value Id driven by the open-loop I / F can be calculated.

[0037] Furthermore, the actual position angle of the motor rotor is obtained based on the power angle and open-loop angle, and the ball screw stroke is determined based on the actual position angle, including: according to Calculate the actual position angle of the motor rotor; in, This refers to the actual position angle. This is the open-loop angle.

[0038] Alternatively, following the above method, the D-axis current Id that varies with the load can be obtained, as well as the actual rotor position angle of the motor: that is, actual rotor angle = open-loop given angle - given power angle, and finally the stroke is calculated based on the actual rotor angle.

[0039] The solution in this embodiment uses the pressure / clamping force sensor in the EHB / EMB line control product to obtain the system load status, and accurately calculates the D-axis current and the actual position of the motor rotor required for I / F contactless control based on the load status, thereby improving the matching degree between the D-axis current and the actual system load and the accuracy of the ball screw stroke calculation.

[0040] Example 2 Figure 3 This is a schematic diagram of the motor control system of the present invention, as shown below. Figure 3 This application also provides a motor control system, including: a relationship construction module, a data acquisition module, a data processing module, and a control module.

[0041] The relationship building module is used to create and store a mapping table between torque and load.

[0042] The data acquisition module is used to acquire real-time load signals, given power angles, open-loop angles, and to look up the corresponding torque based on the real-time load. The data processing module is also used to obtain the D-axis current corresponding to the open-loop coordinate system based on the torque and given power angles, to obtain the actual position angle of the motor rotor based on the power angle and open-loop angles, and to determine the ball screw stroke based on the actual position angle.

[0043] The control module is used to control the motor based on the ball screw travel and D-axis current.

[0044] Furthermore, the control module is also used for closed-loop speed control of the motor; The relationship building module is also used to record the estimated torque curve and load curve of the motor, and to establish a mapping relationship table between load and torque based on the estimated torque curve and load curve of the motor.

[0045] Furthermore, the data processing module is also used to obtain the Q-axis current in the open-loop coordinate system based on the torque and torque equation, and to obtain the required D-axis current based on the Q-axis current and the given power angle.

[0046] Furthermore, the data processing module is also used for: According to the torque equation Obtain the Q-axis current in the open-loop coordinate system. And according to trigonometric functions Obtain the required D-axis current.

[0047] Optionally, the data processing module also includes a ball screw stroke calculation module, used for: according to Calculate the actual position angle of the motor rotor, and determine the ball screw stroke based on the actual position angle.

[0048] Example 3 This application also provides a vehicle including the aforementioned motor control system.

[0049] Specifically, the motor control system includes a relationship building module, a data acquisition module, a data processing module, and a control module.

[0050] The relationship building module is used to create and store a mapping table between torque and load.

[0051] The data acquisition module is used to acquire real-time load signals, given power angles, open-loop angles, and to look up the corresponding torque based on the real-time load. The data processing module is also used to obtain the D-axis current corresponding to the open-loop coordinate system based on the torque and given power angles, to obtain the actual position angle of the motor rotor based on the power angle and open-loop angles, and to determine the ball screw stroke based on the actual position angle.

[0052] The control module is used to control the motor based on the ball screw travel and D-axis current.

[0053] Furthermore, the control module is also used for closed-loop speed control of the motor; The relationship building module is also used to record the estimated torque curve and load curve of the motor, and to establish a mapping relationship table between load and torque based on the estimated torque curve and load curve of the motor.

[0054] Furthermore, the data processing module is also used to obtain the Q-axis current in the open-loop coordinate system based on the torque and torque equation, and to obtain the required D-axis current based on the Q-axis current and the given power angle.

[0055] Furthermore, the data processing module is also used for: According to the torque equation Obtain the Q-axis current in the open-loop coordinate system. And according to trigonometric functions Obtain the required D-axis current.

[0056] Optionally, the data processing module also includes a ball screw stroke calculation module, used for: according to Calculate the actual position angle of the motor rotor, and determine the ball screw stroke based on the actual position angle.

[0057] Figure 4 This is a schematic diagram of the vehicle of the present invention, as shown below. Figure 4 As shown, the vehicle also includes: an EHB / EMB system, a sensor, a PI regulator, a 2r / 2s converter, a pulse width modulation module, and a motor controller; the EHB / EMB system is electrically connected to the sensor, the sensor and the PI regulator are communicatively connected to the system of this application, the PI regulator is connected to the pulse width modulation module through the 2r / 2s converter, and the pulse width modulation module is electrically connected to the motor through the motor controller; the motor controller is also connected to a DC power supply.

[0058] In the vehicle provided in this application, a sensor is installed on the EHB / EMB system to acquire the current motor load of the actuator system and output it as pressure / clamping force to the motor control system of this application. By calibrating the mapping relationship, the load torque at the motor end under different system loads can be obtained. Using the electromagnetic torque formula, the actual Q-axis current Iq required to counteract the load can be obtained. Finally, different operating power angle commands are set according to different load conditions, and the open-loop I / F driven D-axis current Id is calculated based on the actual Q-axis current Iq and the power angle. While obtaining the D-axis current Id that varies with the load, the actual rotor position angle of the motor is also obtained. Finally, this actual rotor angle is sent to the ball screw stroke calculation module for stroke calculation.

[0059] In this embodiment, the calculated D-axis current Id is output to a PI regulator, which adjusts and changes the output DC control voltage Ud to a 2r / 2s converter. The 2r / 2s converter then converts the DC control voltage Ud into an AC voltage Ub through an inverse Park converter. Finally, the AC voltage Ub is converted into a PWM waveform by a pulse width modulation module. The motor controller then drives and controls the motor based on the PWM waveform and the ball screw travel.

[0060] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0061] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and represent a limitation on a specific order or sequence. Where appropriate, the order of use for similar objects can be interchanged so that the embodiments of this application described herein can be implemented in an order other than that shown or described.

[0062] Those skilled in the art will recognize that this invention can be implemented as a system, method, or computer program product. Therefore, this invention can be specifically implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, this invention can also be implemented as a computer program product contained in one or more computer-readable media, which includes computer-readable program code.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A motor control method, characterized in that, include: Establish a mapping table between torque and load; Obtain the real-time load, and look up the corresponding torque in the mapping table based on the real-time load; Based on the torque and the given power angle, the D-axis current corresponding to the open-loop coordinate system is obtained; The actual position angle of the motor rotor is obtained based on the power angle and the open-loop angle, and the ball screw stroke is determined based on the actual position angle. The motor is controlled based on the ball screw travel and the D-axis current.

2. The method according to claim 1, characterized in that, The establishment of the mapping table between torque and load includes: Perform closed-loop speed control on the motor and record the estimated torque curve and load curve of the motor; A mapping table between load and torque is established based on the estimated torque curve of the motor and the load curve.

3. The method according to claim 2, characterized in that, Based on the torque and the given power angle, the D-axis current corresponding to the open-loop coordinate system is obtained, including: The Q-axis current in the open-loop coordinate system is obtained based on the torque and torque equation. The required D-axis current is obtained based on the Q-axis current and the given power angle.

4. The method according to claim 3, characterized in that, The Q-axis current in the open-loop coordinate system is obtained based on the torque and torque equation, including: According to the torque equation Thus, the Q-axis current in the open-loop coordinate system is obtained; in, This refers to the motor torque. This represents the number of pole pairs of the motor. For the rotor flux of the motor, For the D-axis inductance of the motor, For the Q-axis inductance of the motor, This represents the D-axis current.

5. The method according to claim 4, characterized in that, The required D-axis current is obtained based on the Q-axis current and the given power angle, including: According to trigonometric functions To obtain the required D-axis current; in, This is the Q-axis current. Given the angle of attack.

6. The method according to claim 5, characterized in that, The actual position angle of the motor rotor is obtained based on the power angle and open-loop angle, and the ball screw stroke is determined based on the actual position angle, including: according to Calculate the actual position angle of the motor rotor; in, This refers to the actual position angle. This is the open-loop angle.

7. A motor control system, characterized in that, include: Relationship building module, data acquisition module, data processing module, control module; The relationship building module is used to establish and store a mapping relationship table between torque and load; The data acquisition module is used to acquire real-time load signals, given power angles, open-loop angles, and to look up the corresponding torque based on the real-time load. The data processing module is used to obtain the D-axis current corresponding to the open-loop coordinate system based on the torque and the given power angle, obtain the actual position angle of the motor rotor based on the power angle and the open-loop angle, and determine the ball screw stroke based on the actual position angle. The control module is used to control the motor according to the ball screw stroke and the D-axis current.

8. The system according to claim 7, characterized in that, The control module is also used for closed-loop speed control of the motor; The relationship building module is also used to record the estimated torque curve and load curve of the motor, and to establish a mapping relationship table between load and torque based on the estimated torque curve and the load curve.

9. The system according to claim 8, characterized in that, The data processing module is also used to obtain the Q-axis current in the open-loop coordinate system based on the torque and the torque equation, and to obtain the required D-axis current based on the Q-axis current and the given power angle.

10. The system according to claim 9, characterized in that, The data processing module is also used for: According to the torque equation Obtain the Q-axis current in the open-loop coordinate system. And according to trigonometric functions Obtain the required D-axis current.

Images