Motor torque control device and method

Abstract

The invention relates to a motor torque control device, which comprises a control unit and an inverter circuit, and is characterized in that the control unit further comprises a current detection module used for detecting phase current flowing through each phase winding of a motor; the current correction module is used for adjusting the gain coefficient of each phase current detected by the current detection module according to at least one current operation parameter of the motor; the torque correction module is used for correcting a torque request value according to the operation parameters so as to obtain compensated control torque; the reference current determination module is used for determining a current reference value for controlling the motor according to the compensated control torque; and the single chip microcomputer is configured to control the output torque of the motor based on the corrected phase current and the current reference value. The invention further relates to an electric drive system comprising the device and a motor torque control method.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control, and more specifically, to a motor torque control device and method, and an electric drive system for a vehicle including the motor torque control device. Background Art

[0002] In the process of motor drive control of the vehicle, the phase current detection of the motor is a key link, and its measurement results directly affect the control accuracy of the motor torque and even the overall driving performance of the vehicle. For example, for permanent magnet synchronous motors, its phase current detection mostly adopts direct measurement method, that is, the three-phase line current after the drive circuit is inverted is directly measured by current sensor. The specific measurement circuit can usually be divided into resistance sampling, current transformer sampling and sampling through Hall current sensor. The current detection accuracy of these measurement circuits has certain limitations.

[0003] For the motor products currently on the market, the same gain coefficient is used to measure the current of each phase. Due to the random errors, temperature and speed differences in different hardware in the current detection loop, applying the same gain coefficient to all phase currents will lead to a decrease in current detection accuracy, which in turn will lead to a decrease in motor torque control accuracy, which affects the overall performance of the vehicle. Summary of the invention

[0004] In view of this, according to a first aspect of the present invention, a motor torque control device is provided, the device comprising a control unit and an inverter circuit, the control unit being configured to output a corresponding DC control signal to the inverter circuit based on a torque request value received from a vehicle bus, the inverter circuit being configured to output a corresponding AC drive signal to the motor based on the DC control signal received from the control unit to control the output torque of the motor, wherein the control unit further comprises:

[0005] A current detection module, the current detection module is used to detect the phase current flowing through each phase winding of the motor;

[0006] A current correction module, the current correction module is used to adjust the gain coefficient of each phase current detected by the current detection module according to at least one current operating parameter of the motor to obtain a corrected phase current;

[0007] a torque correction module, the torque correction module being used to correct the torque request value according to at least one current operating parameter of the motor to obtain a compensated control torque;

[0008] A reference current determination module, the reference current determination module is used to determine a current reference value i for controlling the motor according to the compensated control torque dref ,i qref ;as well as

[0009] The single chip microcomputer is configured to dref ,i qref To control the output torque of the motor.

[0010] Advantageously, the single chip microcomputer is configured to use a motor vector control algorithm to adjust the output torque of the motor.

[0011] Advantageously, the current reference value i dref ,i qref is the current in the dq coordinate system, and the single chip is further configured to convert the corrected phase current into a current value i in the dq coordinate system d ,i q Based on the current value i d ,i q With the current reference value i dref ,i qref The comparison result is used to adjust the output torque of the motor.

[0012] Advantageously, the motor vector control algorithm comprises: converting the corrected phase current into a current value i in the dq coordinate system by means of Clarke transformation and Park transformation. d ,i q .

[0013] Advantageously, the motor vector control algorithm further comprises: using a PI regulator based on the current value i d ,i q With the current reference value i dref ,i qref The comparison result between them determines the control voltage u in the dq coordinate system. dref ,u qref , and based on the control voltage u dref ,u qref SVPWM is used to control the state of each switch tube in the inverter circuit, thereby adjusting the output torque of the motor.

[0014] Advantageously, the at least one operating parameter includes a current rotational speed and an operating temperature of the motor.

[0015] According to a second aspect of the present invention, an electric drive system for a vehicle is also proposed, the electric drive system comprising:

[0016] Motor; and

[0017] The motor torque control device as described above.

[0018] Advantageously, the motor is a permanent magnet synchronous motor.

[0019] Advantageously, the control unit forms part of a motor controller.

[0020] According to a third aspect of the present invention, a motor torque control method is also provided. The method controls the output torque of the motor based on a torque request value received from a vehicle bus. The method comprises the following steps:

[0021] Detecting the phase current flowing through each phase winding of the motor;

[0022] Determine at least one current operating parameter of the motor, and adjust the gain coefficient of each detected phase current based on the at least one operating parameter to obtain a corrected phase current;

[0023] Correcting the torque request value according to at least one current operating parameter of the motor to obtain a compensated control torque;

[0024] Determine the current reference value i for controlling the motor according to the compensated control torque dref ,i qref ;as well as

[0025] Based on the corrected phase current and the current reference value i dref ,i qref To control the output torque of the motor.

[0026] According to the motor torque control device of the present invention, it can perform gain compensation on each phase current measured based on working parameters such as motor speed and temperature to obtain a corrected phase current, which is further converted to the dq rotating coordinate system, that is, the current value i in the dq coordinate system is obtained. d ,i q , so as to compare with the reference current i obtained by looking up the torque table dref ,i qref For comparison, based on the comparison results of the two, the dq axis voltage can be obtained by means of the PI regulator, and then the control signal for controlling the switching state of the inverter can be obtained through the Park inverse transformation and SVPWM, that is, the actual current of the stator winding of the control motor is obtained, thereby controlling the torque output of the motor. Compared with the traditional torque control scheme in which each phase current adopts the same gain coefficient, the motor torque control device according to the present invention can reduce the difference between the measurement results of each phase current, thereby improving the torque control accuracy and control efficiency of the motor, thereby improving the stability and safety of vehicle driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] By incorporating the accompanying drawings and Figure 1 With reference to the specific embodiments used to illustrate certain principles of the present invention, other features and advantages of the method of the present invention will become clear or be described in more detail.

[0028] Figure 1 A schematic diagram of a conventional vehicle electric drive system is shown.

[0029] Figure 2 A structural diagram of a motor torque control device according to an exemplary embodiment of the present invention is shown.

[0030] Figure 3 A schematic diagram of a motor vector control algorithm according to an exemplary embodiment of the present invention is shown.

[0031] Figure 4 An operation flow chart of a motor torque control method according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0032] The motor torque control device according to the present invention will be described below with reference to the accompanying drawings and by way of example. In the following description, many specific details are set forth so that a person skilled in the art can more fully understand the present invention. However, it is obvious to a person skilled in the art that the present invention may be implemented without some of these specific details. Instead, it is contemplated that the present invention may be implemented with any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following various aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims.

[0033] Figure 1 FIG. 1 shows a schematic diagram of a conventional vehicle electric drive system. Figure 1 As shown in the figure, the electric drive system is mainly composed of a motor M, an inverter circuit H, a control unit ECU and an electric HV.

[0034] Here, the motor M may be a three-phase motor, in particular, a permanent magnet synchronous motor M (abbreviated as "PMSM") that can be applied to the BSG system of a hybrid vehicle. The motor may be driven by an inverter circuit, which specifically includes an electronic control unit ECU and an inverter bridge H composed of a plurality of bridge arms T1, T2, T3, T4, T5, and T6, wherein the switch tubes T1, T3, and T5 form an upper bridge arm, and the switch tubes T2, T4, and T6 form a lower bridge arm.

[0035] Here, each bridge arm may be selected from the group consisting of a field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT) and a bipolar junction transistor (BJT). Figure 1 The N-channel MOS tube is used as an example for illustration.

[0036] The gate control end of each switch tube in the inverter bridge H can be connected to the motor control circuit board ECU, and the control circuit board ECU controls the conduction of each switch tube by outputting a PWM duty cycle signal to the switch tube, thereby controlling the running speed and direction of the motor.

[0037] During the operation of the above motor, the detection of the motor phase current is particularly important, and the detection accuracy of the phase current directly affects the control accuracy of the motor torque. For the motor products currently on the market, the same gain coefficient is used for the detection process of each phase current. Due to the random errors, temperature and speed differences of different hardware in the current detection loop, applying the same gain coefficient to all phase currents will lead to a decrease in current detection accuracy, which in turn leads to a decrease in motor torque control accuracy, which affects the overall performance of the vehicle.

[0038] In order to ensure the consistency of detection results of different phase currents of a motor and to improve the control accuracy of the motor torque, the present invention proposes a new motor torque control device. Figure 2 A structural diagram of a motor torque control device according to an exemplary embodiment of the present invention is shown.

[0039] like Figure 2 As shown in , the torque control device mainly includes two parts: a control unit and an inverter circuit. The control unit is configured to output a corresponding DC control signal to the inverter circuit based on a torque request value received from a vehicle bus (such as a CAN bus), and the inverter circuit is configured to output a corresponding AC drive signal to the motor based on the DC control signal received from the control unit to control the output torque of the motor.

[0040] The control unit is the core of the torque control device, see Figure 2 , which includes a current detection module, a current correction module, a torque correction module, a reference current determination module and a single-chip microcomputer. The current detection module is used to detect the phase current flowing through each phase winding of the motor (for example, the three-phase winding of U, V, and W). For the measurement results of each phase current, the same gain coefficient is used. Since there are random errors between different hardware in the current detection loop, the phase current measurement accuracy is reduced due to temperature changes, and there are deviations in the current measurement accuracy at different speeds. Therefore, it is considered to use the current correction module to dynamically adjust the gain coefficient of each phase current.

[0041] Specifically, the current correction module can adjust the gain coefficient of each phase current detected by the current detection module according to at least one current operating parameter of the motor (especially the current speed and operating temperature of the motor) to obtain a corrected phase current.

[0042] Due to the parameter errors of various components in the hardware circuit, there is a certain error between the actual torque value and the torque request value received from the CAN bus. Therefore, the torque correction module can be used to correct the torque request value received from the CAN bus according to at least one current operating parameter of the motor to obtain a compensated control torque, and the reference current determination module can be used to determine the current reference value i for controlling the motor according to the compensated control torque. dref ,i qref .

[0043] The current reference value i dref ,i qref The same can also be further transmitted to the single chip microcomputer to control the output torque of the motor based on the corrected phase current and the current reference value.

[0044] The control process of the motor output torque of the single chip microcomputer can be executed by using a motor vector control algorithm. Figure 3 A schematic diagram of a motor vector control algorithm according to an exemplary embodiment of the present invention is shown.

[0045] The electromagnetic torque equation of the permanent magnet synchronous motor is as follows. The torque of the permanent magnet synchronous motor can be controlled by controlling the torque component of the stator current:

[0046]

[0047] In the above formula, T e is the given torque of the motor, is the rotor flux, i d ,i q is the direct-axis current in the dq coordinate system, L d , L q is the motor inductance.

[0048] The current reference value i obtained by the reference current determination module dref ,i qref is the current in the dq coordinate system. The corrected phase current obtained by the current correction module can be further sent to the single-chip microcomputer, where the phase current can be converted into the current value i in the dq coordinate system (for example, by using Clarke transformation and Park transformation). d ,i q .

[0049] The microcontroller can be based on the current value i d , f q With the current reference value i dref ,i qref Specifically, in the motor vector control algorithm, the PI regulator is used to adjust the output torque of the motor based on the current value i d , fq With the current reference value i dref ,i qref The comparison result between them is used to generate the control voltage u in the dq coordinate system. dref ,u qref , and convert it based on Park inverse transform, and finally use SVPWM (space voltage vector pulse width modulation technology) to control the state of each switch tube in the inverter circuit, thereby adjusting the output torque of the motor.

[0050] An exemplary embodiment of the present invention also relates to an electric drive system for a vehicle, comprising a motor and a motor torque control device as described above. The motor may be, for example, a permanent magnet synchronous motor M (abbreviated as "PMSM"), and the control unit may, for example, form part of a motor controller.

[0051] Figure 4 The operation flow chart of the motor torque control method according to an exemplary embodiment of the present invention is shown. The method can control the output torque of the motor based on the torque request value received from the vehicle bus.

[0052] First, in step S101, the phase current flowing through each phase winding of the motor is detected, and the gain coefficient of each phase current can be determined (for example, by looking up a table) according to the detection data. Then, in step S102, at least one current operating parameter of the motor (including motor speed, motor temperature, etc.) can be further determined, and based on the operating parameter, the gain coefficient corresponding to each phase current can be adjusted accordingly to obtain a corrected phase current.

[0053] Further, in step S103, the torque request value may be corrected according to at least one current operating parameter of the motor to obtain a compensated control torque. Subsequently, in step S104, a current reference value i for controlling the motor may be determined based on the compensated control torque. dref ,i qref Based on the current reference value and the phase current after the power supply correction determined in step S102, the output torque of the motor can be adjusted accordingly.

[0054] It can be understood that the current reference value i determined in step S104 is dref ,i qref is the current in the dq coordinate system. In order to compare with this current, the corrected phase current needs to be converted into the current value i in the dq coordinate system in step S105. d ,i q In step S106, based on the current value i d ,i q With the current reference value i dref ,i qref The comparison result between them can adjust the output torque of the motor.

[0055] According to the motor torque control device of the present invention, gain compensation can be performed on each phase current measured based on working parameters such as motor speed and temperature to obtain a corrected phase current, which is further converted to a dq rotating coordinate system, that is, the current value i in the dq coordinate system is obtained. d ,i q , so as to compare with the reference current i obtained by looking up the torque table dref ,i qref For comparison, based on the comparison results of the two, the dq axis control voltage u can be obtained with the help of the PI regulator dref ,u qref , and then the control signal for controlling the switching state of the inverter is obtained through Park inverse transformation and SVPWM, that is, the actual current of the stator winding of the motor is obtained to control the torque output of the motor. Compared with the traditional torque control scheme in which each phase current adopts the same gain coefficient, the motor torque control device according to the present invention can reduce the difference between the measurement results of each phase current, thereby improving the torque control accuracy and control efficiency of the motor, and thus improving the stability and safety of vehicle driving.

[0056] In this article, the "dq axis" of the motor refers to the direct axis and quadrature axis of the motor, wherein the direct axis is also called the d axis, which is aligned with the direction of the motor rotor magnetic field; and the quadrature axis is also called the q axis, which is perpendicular to the direction of the motor rotor magnetic field. Therefore, those skilled in the art can understand that the term "dq axis current (or inductance)" refers to the d axis current (or inductance) and the q axis current (or inductance).

[0057] It will be appreciated by those skilled in the art that the various steps of the method according to the present invention can be performed in a given order. However, it should be noted that different orders are also possible. The method may include other method steps that are not listed. In addition, one or more of the method steps may be performed once or repeated. In addition, two or more of the method steps may be performed simultaneously or in a temporally overlapping manner. In addition, it should be noted that the term "at least one", "one or more" or similar expressions indicating that a feature or element may exist one or more than one are usually used only once when introducing the corresponding feature or element. As further used herein, in most cases, when referring to the corresponding feature or element, the expression "at least one" or "one or more" is not repeatedly mentioned, but this does not exclude that the corresponding feature or element may exist once or more than once.

[0058] Although the present invention has been disclosed as above with preferred embodiments, the present invention is not limited thereto. Any changes and modifications made by any person skilled in the art without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention, and therefore the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A motor torque control device, characterized in that: The device includes a control unit and an inverter circuit, wherein the control unit is configured to output a corresponding DC control signal to the inverter circuit based on a torque request value received from a vehicle bus, and the inverter circuit is configured to output a corresponding AC drive signal to the motor based on the DC control signal received from the control unit to control the output torque of the motor, wherein the control unit further includes: A current detection module, the current detection module is used to detect the phase current flowing through each phase winding of the motor; A current correction module, the current correction module is used to adjust the gain coefficient of each phase current detected by the current detection module according to at least one current operating parameter of the motor to obtain a corrected phase current; a torque correction module, the torque correction module being used to correct the torque request value according to at least one current operating parameter of the motor to obtain a compensated control torque; A reference current determination module, the reference current determination module is used to determine a current reference value i for controlling the motor according to the compensated control torque dref ,i qref ;as well as The single chip microcomputer is configured to dref ,i qref To control the output torque of the motor.

2. The motor torque control device according to claim 1, characterized in that: The single chip microcomputer is configured to use a motor vector control algorithm to adjust the output torque of the motor.

3. The motor torque control device according to claim 2, characterized in that: The current reference value i dref ,i qref is the current in the dq coordinate system, and the single chip is further configured to convert the corrected phase current into a current value i in the dq coordinate system d ,i q Based on the current value i d ,i q With the current reference value i dref ,i qref The comparison result is used to adjust the output torque of the motor.

4. The motor torque control device according to claim 3, characterized in that: The motor vector control algorithm includes: using Clarke transformation and Park transformation to convert the corrected phase current into the current value i in the dq coordinate system d ,i q .

5. The motor torque control device according to claim 3, characterized in that: The motor vector control algorithm further includes: using a PI regulator based on the current value i d ,i q With the current reference value i dref ,i qref The comparison result between them determines the control voltage u in the dq coordinate system. dref ,u qref , and based on the control voltage u dref ,u qref SVPWM is used to control the state of each switch tube in the inverter circuit, thereby adjusting the output torque of the motor.

6. The motor torque control device according to any one of claims 1 to 5, characterized in that: The at least one operating parameter includes a current rotation speed and an operating temperature of the motor.

7. An electric drive system for a vehicle, characterized in that: The electric drive system includes: Motor; and The motor torque control device according to any one of claims 1 to 6.

8. The electric drive system according to claim 7, characterized in that: The motor is a permanent magnet synchronous motor.

9. The electric drive system according to claim 7 or 8, characterized in that: The control unit forms part of a motor controller.

10. A motor torque control method, the method controlling the output torque of a motor based on a torque request value received from a vehicle bus, characterized in that: The method comprises the following steps: Detecting the phase current flowing through each phase winding of the motor; Determine at least one current operating parameter of the motor, and adjust the gain coefficient of each detected phase current based on the at least one operating parameter to obtain a corrected phase current; Correcting the torque request value according to at least one current operating parameter of the motor to obtain a compensated control torque; Determine the current reference value i for controlling the motor according to the compensated control torque dref ,i qref ;as well as Based on the corrected phase current and the current reference value i dref ,i qref To control the output torque of the motor.

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