Pulse width modulation algorithm and system for automobile motor control
The inverter efficiency and torque control accuracy are optimized through the segmented algorithm, and the half-frequency, Flat-Top SVPWM and seven-segment SVPWM are adopted to solve the problem that traditional algorithms are difficult to take into account efficiency and accuracy, and the efficient control of the motor under different working conditions is achieved.
Patent Information
- Application Number
- CN202510672894.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-08-12
AI Technical Summary
The traditional pulse width modulation algorithm is difficult to achieve low inverter power loss and high torque control accuracy at the same time under all operating conditions of the motor, and is of low practicality.
The segmentation algorithm is adopted, including half-frequency SVPWM, Flat-Top SVPWM and seven-segment SVPWM, and the common-mode voltage and zero-vector action time are calculated through mathematical formulas, and combined with the M68HC08 microcontroller and communication control module, frequency switching and PWM waveform output are realized.
Under different working conditions, the inverter efficiency and torque control accuracy are optimized through the segmented algorithm, which improves the practicality of the motor. The inverter efficiency is increased by 4.23% to 0.44%, and the torque control accuracy is increased by 0.24% to 0.35%.
Smart Images
Figure CN120474412A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of modulation algorithms, and in particular to a pulse width modulation algorithm and system for controlling an automobile motor. Background Art
[0002] Pulse-width modulation technology is widely used in motor control. By varying the pulse width to adjust the average voltage, precise control of motor speed and torque is achieved. PWM controllers, such as PWMMC, are typically integrated into microcontrollers or integrated circuits, and are particularly prominent in the M68HC08 microcontroller. This controller generates PWM signals by configuring timers and compare registers, and can perform closed-loop control using software algorithms such as PID controllers. Motor control strategies include unipolar PWM, bipolar PWM, vector control, and torque control.
[0003] Pulse width modulation is a commonly used technology, especially in the field of motor control. It controls the speed and torque of the motor by adjusting the width of the pulse. PWM allows the motor to provide high-efficiency output while consuming low power, which makes it an ideal choice for driving motors. The main advantage of PWM technology is that it can control complex analog circuits through simple digital signals, which greatly simplifies the design of the motor drive circuit. By using the duty cycle of the PWM control signal, the average voltage and current of the motor can be accurately adjusted, thereby achieving fine control of the motor speed and torque.
[0004] However, the traditional pulse width modulation algorithm has the following disadvantages:
[0005] Under all working conditions of the motor, it is difficult to achieve both low inverter power loss and high torque control accuracy by using a single type of SVPWM modulation method, and its practicality is low. Summary of the Invention
[0006] The purpose of the present invention is to provide a pulse width modulation algorithm and system for automobile motor control, so as to solve the problem raised in the above background art that it is difficult to achieve both low inverter power loss and high torque control accuracy under all motor operating conditions using a single type of SVPWM modulation method, and the problem of low practicality.
[0007] To achieve the above objectives, the present invention provides the following technical solutions: a pulse width modulation algorithm for automobile motor control, including a segmented algorithm, wherein the segmented algorithm includes half-frequency SVPWM, Flat-Top SVPWM and seven-segment SVPWM.
[0008] As a preferred technical solution of the present invention, the common-mode voltage formula of the SVPWM in the half-frequency SVPWM is derived through mathematical derivation. In the standard three-phase SVPWM, the following formula is used to calculate the common-mode voltage:
[0009]
[0010] Where V0 represents the common-mode voltage, and V1, V2, and V3 represent the A-phase, B-phase, and C-phase voltages of the inverter, respectively, indicating that the common-mode voltage is the average value of the three-phase voltages.
[0011] The calculation formula for the time of zero vector action is:
[0012]
[0013] As a preferred technical solution of the present invention, the Flat-Top SVPWM; since each PWM cycle is divided into seven segments, the action time of each vector should also be adjusted. Here, the action time of the zero vector is:
[0014]
[0015] Since the DSP event manager EV has three comparison registers, each comparison unit controls two groups of PWM pulses, which just realizes the seven-segment SVPWM. Some time variables T are introduced. a , T b , T c , the calculation formula is as follows:
[0016]
[0017] As a preferred technical solution of the present invention, the seven-segment SVPWM is based on the basic principle of SVPWM. As long as the action time t1 and t2 of two adjacent non-zero voltage vectors are kept constant, the synthesized space voltage vector is kept constant. For the zero vectors 000 and 111, only the total action time (T PWM -t1-t2) remains unchanged, and their respective action times are not constrained. This involves the problem of optimizing the distribution of zero vectors. In order to accurately calculate the action time of each zero vector, a zero vector distribution factor calculation formula is defined as follows:
[0018]
[0019] Where: T0 is the action time of zero vector 000; T1 is the action time of zero vector 111.
[0020] The present invention provides a pulse width modulation algorithm system for automobile motor control, comprising an algorithm system, wherein the algorithm system comprises a frequency switching module, an M68HC08 single chip microcomputer and a communication control module;
[0021] The frequency switching module determines the algorithm based on the actual operating frequency of the motor. The M68HC08 microcontroller controls the operation of the algorithm in real time. The communication control module provides multiple communication interfaces, such as SPI, SCI, and I2C, through which data exchange and control with external devices are realized.
[0022] As a preferred technical solution of the present invention, the frequency switching module includes a Flat-Top SVPWM and seven-segment SVPWM frequency switching submodule, a half-frequency SVPWM and Flat-Top SVPWM frequency switching submodule, and a seven-segment SVPWM and half-frequency SVPWM frequency switching submodule;
[0023] The Flat-Top SVPWM and seven-segment SVPWM frequency switching submodule performs Flat-Top SVPWM and seven-segment SVPWM algorithm conversion within a fixed frequency. The half-frequency SVPWM and Flat-Top SVPWM frequency switching submodule performs half-frequency SVPWM and Flat-Top SVPWM algorithm conversion within a fixed frequency. The seven-segment SVPWM and half-frequency SVPWM frequency switching submodule performs seven-segment SVPWM and half-frequency SVPWM algorithm conversion within a fixed frequency.
[0024] As a preferred technical solution of the present invention, the M68HC08 single chip microcomputer includes a PWM control register, a comparison register and an output control logic module;
[0025] The PWM control register is used to configure the PWM mode, polarity, and dead time. The compare register is used to set the PWM period and pulse width. The output control logic module generates a PWM waveform output based on the compare register value and the control register settings.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] 1. Determine 45.17 Hz as the switching point between half-frequency SVPWM and Flat-Top SVPWM, and 310.09 Hz as the switching point between Flat-Top SVPWM and seven-segment SVPWM;
[0028] 2. When the automotive motor controller does not have high requirements for inverter efficiency but has high requirements for torque control accuracy, the seven-segment SVPWM is used in the entire speed range;
[0029] 3. When the automotive motor controller does not have high requirements for torque control accuracy but has high requirements for inverter efficiency, half-frequency SVPWM is used in the entire speed range;
[0030] 4. When the automotive motor controller needs to take into account both inverter efficiency and motor torque control accuracy, a combined SVPWM modulation algorithm is used. That is, half-frequency SVPWM is used in the low-speed range, Flat-Top SVPWM is used in the medium-speed range, and seven-segment SVPWM is used in the high-speed range, which is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 Schematic diagram of the architecture of the algorithm system of the present invention;
[0032] Figure 2 Schematic diagram of the frequency switching module of the present invention;
[0033] Figure 3 Schematic diagram of the architecture of the M68HC08 single-chip microcomputer of the present invention. DETAILED DESCRIPTION
[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0035] See also Figure 1-3 The present invention provides a pulse width modulation algorithm for automobile motor control, including a segmented algorithm, which includes a half-frequency SVPWM, a Flat-Top SVPWM and a seven-segment SVPWM.
[0036] The common-mode voltage formula of SVPWM in half-frequency SVPWM is derived through mathematical derivation. In standard three-phase SVPWM, the following formula is used to calculate the common-mode voltage:
[0037]
[0038] Where V0 represents the common-mode voltage, and V1, V2, and V3 represent the A-phase, B-phase, and C-phase voltages of the inverter, respectively, indicating that the common-mode voltage is the average value of the three-phase voltages.
[0039] The calculation formula for the time of zero vector action is:
[0040]
[0041] Flat-Top SVPWM; Since each PWM cycle is divided into seven segments, the action time of each vector should also be adjusted. Here, the action time of the zero vector is:
[0042]
[0043] Since the DSP event manager EV has three comparison registers, each comparison unit controls two groups of PWM pulses, which just realizes the seven-segment SVPWM. Some time variables T are introduced. a , T b , T c , the calculation formula is as follows:
[0044]
[0045] According to the basic principle of SVPWM, the seven-segment SVPWM can ensure that the composite space voltage vector remains unchanged as long as the action time t1, t2 of two adjacent non-zero voltage vectors remains unchanged. For the zero vectors 000 and 111, only the total action time (T PWM -t1-t2) remains unchanged, and their respective action times are not constrained. This involves the problem of optimizing the distribution of zero vectors. In order to accurately calculate the action time of each zero vector, a zero vector distribution factor calculation formula is defined as follows:
[0046]
[0047] Where: T0 is the action time of zero vector 000; T1 is the action time of zero vector 111.
[0048] The present invention provides a pulse width modulation algorithm system for automobile motor control, comprising an algorithm system, wherein the algorithm system comprises a frequency switching module, an M68HC08 single chip microcomputer and a communication control module;
[0049] The frequency switching module determines the algorithm based on the actual operating frequency of the motor. The M68HC08 microcontroller controls the operation of the algorithm in real time. The communication control module provides multiple communication interfaces, such as SPI, SCI, and I2C, through which data exchange and control with external devices are realized.
[0050] The frequency switching module includes Flat-Top SVPWM and seven-segment SVPWM frequency switching submodule, half-frequency SVPWM and Flat-Top SVPWM frequency switching submodule, and seven-segment SVPWM and half-frequency SVPWM frequency switching submodule;
[0051] The Flat-Top SVPWM and seven-segment SVPWM frequency switching submodule performs Flat-Top SVPWM and seven-segment SVPWM algorithm conversion within a fixed frequency. The half-frequency SVPWM and Flat-Top SVPWM frequency switching submodule performs half-frequency SVPWM and Flat-Top SVPWM algorithm conversion within a fixed frequency. The seven-segment SVPWM and half-frequency SVPWM frequency switching submodule performs seven-segment SVPWM and half-frequency SVPWM algorithm conversion within a fixed frequency.
[0052] The M68HC08 microcontroller includes PWM control registers, comparison registers and output control logic modules;
[0053] The PWM control register is used to configure the PWM mode, polarity, and dead time. The compare register is used to set the PWM period and pulse width. The output control logic module generates a PWM waveform output based on the compare register value and the control register settings.
[0054] In the present invention, 45.17 Hz is determined as the switching point between half-frequency SVPWM and Flat-Top SVPWM, and 310.09 Hz is determined as the switching point between Flat-Top SVPWM and seven-segment SVPWM. The PWM control register is used to configure the PWM mode, polarity, and dead time. The comparison register is used to set the PWM period and pulse width. The output control logic module generates a PWM waveform output based on the value of the comparison register and the setting of the control register. The communication control module provides multiple communication interfaces, such as SPI, SCI, and I2C, through which data exchange and control with external devices are achieved. The combined SVPWM modulation algorithm is applied to the automotive motor prototype used in the test, that is, half-frequency SVPWM is used when the motor stator frequency is below 45.17 Hz, and Flat-Top SVPWM is used when the motor stator frequency is between 45.17 and 310.09 Hz. SVPWM, using seven-segment SVPWM above the motor stator frequency of 310.09Hz, obtains the performance comparison of the combined SVPWM and the other three SVPWMs. Compared with the three SVPWM modulation algorithms used alone, the seven-segment method has the highest torque control accuracy and the half-frequency method has the highest inverter efficiency. After using the combined SVPWM modulation algorithm, its torque control accuracy is higher in the low frequency band, close to that of the seven-segment SVPWM, and the inverter efficiency is significantly improved, with a maximum improvement of 4.23%. In the medium frequency band, the torque control accuracy of the combined SVPWM is in the middle, and the inverter efficiency is still greatly improved, only 0.24%-0.35% lower than the half-frequency SVPWM. In the high frequency band, the combined SVPWM has the highest torque control accuracy. Although the inverter efficiency is the lowest, it is only 0.32%-0.44% lower than the half-frequency SVPWM, which is far less than the inverter efficiency value that can be improved in the low and medium frequency bands. The combined SVPWM modulation algorithm plays a role in balancing inverter efficiency and torque control accuracy.
[0055] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A pulse width modulation algorithm for automobile motor control, including a segmented algorithm, characterized in that: The segmented algorithms include half-frequency SVPWM, Flat-Top SVPWM and seven-segment SVPWM.
2. The pulse width modulation algorithm for automobile motor control according to claim 1, characterized in that: The common-mode voltage formula of the SVPWM in the half-frequency SVPWM is derived through mathematical derivation. In the standard three-phase SVPWM, the common-mode voltage is calculated using the following formula: Where V0 represents the common-mode voltage, and V1, V2, and V3 represent the A-phase, B-phase, and C-phase voltages of the inverter, respectively, indicating that the common-mode voltage is the average value of the three-phase voltages. The calculation formula for the time of zero vector action is:
3. The pulse width modulation algorithm for automobile motor control according to claim 1, characterized in that: The Flat-Top SVPWM; Since each PWM cycle is divided into seven segments, the action time of each vector should also be adjusted. Here, the action time of the zero vector is: Since the DSP event manager EV has three comparison registers, each comparison unit controls two groups of PWM pulses, which just realizes the seven-segment SVPWM. Some time variables T are introduced. a , T b , T c , the calculation formula is as follows:
4. The pulse width modulation algorithm for automobile motor control according to claim 1, characterized in that: According to the basic principle of SVPWM, the seven-segment SVPWM can ensure that the synthesized space voltage vector remains unchanged as long as the action time t1, t2 of two adjacent non-zero voltage vectors remains unchanged. However, for the zero vectors 000 and 111, only the total action time (T PWM -t1-t2) remains unchanged, and their respective action times are not constrained. This involves the problem of optimizing the distribution of zero vectors. In order to accurately calculate the action time of each zero vector, a zero vector distribution factor calculation formula is defined as follows: Where: T0 is the action time of zero vector 000; T1 is the action time of zero vector 111.
5. A pulse width modulation algorithm system for automobile motor control according to any one of claims 1 to 4, comprising an algorithm system, characterized in that: The algorithm system includes a frequency switching module, an M68HC08 single chip microcomputer and a communication control module; The frequency switching module determines the algorithm based on the actual operating frequency of the motor. The M68HC08 microcontroller controls the operation of the algorithm in real time. The communication control module provides multiple communication interfaces, such as SPI, SCI, and I2C, through which data exchange and control with external devices are realized.
6. The pulse width modulation algorithm system for automobile motor control according to claim 5, characterized in that: The frequency switching module includes a Flat-Top SVPWM and seven-segment SVPWM frequency switching submodule, a half-frequency SVPWM and Flat-Top SVPWM frequency switching submodule, and a seven-segment SVPWM and half-frequency SVPWM frequency switching submodule; The Flat-Top SVPWM and seven-segment SVPWM frequency switching submodule performs Flat-Top SVPWM and seven-segment SVPWM algorithm conversion within a fixed frequency. The half-frequency SVPWM and Flat-Top SVPWM frequency switching submodule performs half-frequency SVPWM and Flat-Top SVPWM algorithm conversion within a fixed frequency. The seven-segment SVPWM and half-frequency SVPWM frequency switching submodule performs seven-segment SVPWM and half-frequency SVPWM algorithm conversion within a fixed frequency.
7. The pulse width modulation algorithm system for automobile motor control according to claim 5, characterized in that: The M68HC08 single chip microcomputer includes a PWM control register, a comparison register and an output control logic module; The PWM control register is used to configure the PWM mode, polarity, and dead time. The compare register is used to set the PWM period and pulse width. The output control logic module generates a PWM waveform output based on the compare register value and the control register settings.