2012CCDC会议论文
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2 MATHEMATICAL MODEL OF INDUCTe asynchronous motor is a high-level, non-linear, strongly coupled multivariable system. In the establishment process of the mathematical model of asynchronous motors, often make the following assumptions:
(3) Ignore the magnetic saturation core loss, so that magnetic circuit can be expressed with a circuit in the form;
(4) Ignore the frequency and temperature's effects on the winding resistance;
Research on the Direct Torque Control for Asynchronous Motor Based on the Sliding Mode Variable Structure Control
Wei Jianhong, Li Xiaoqian, Zheng Yan
School of Information Science & Engineering, Northeastern University, Shenyang 110819, China. E-mail: zhengyan1@
此项工作得到国家自然科学基金资助, 项目批准号: 61174073
motor's direct torque control in recent years[6-8], to improve system robustness and the speed of response, to reduce the torque ripple and to keep switching frequency constant. This paper studies asynchronous motor's direct torque control problem which is based on sliding mode variable structure. Aimed at the problems of larger torque ripple and unconstant inverter switch frequency in the direct torque control for asynchronous motor, this paper puts forward a control scheme which combined sliding mode variable structure theory with Space Vector PWM technology (SVPWM) to reduce torque ripple and keeps switch frequency constant. The sliding mode variable structure controller is designed based on flux error and torque error, to make the torque and flux fast and accurate adjustment, controller outputs get inverter switch pulse signal by implementing SVPWM modulation which realized the constant frequency inverter switch. In order to reduce the steady-state error of the speed and improve control accuracy, the paper also designed a speed regulator based on sliding mode variable structure control, compared with the conventional PI control, system's response speed has been improved and steady-state error has been reduced.
Key Words: Asynchronous motors, Sliding mode variable structure control, Direct torque control, Torque ripple, Space vector PWM technology
1 INTRODUCTION
The research about reduces the torque ripple of induction motor's direct torque control system and keeps switching frequency constant has been the focus of attention and studied by some scholars at home and abroad. Literature [3] proposed a control scheme based on the duty cycle modulation technique which does not use conventional torque hysteresis comparator, it calculated the time through using mathematical sampling period in a non-zero voltage vector and the respective roles of the zero voltage vector, the simulation method enables the switching frequency approximately constant; Literature [4] designs a torque and flux controller to reduce torque ripple which is PI-based, the simulation results show that the solution reduce the torque ripple in some extent, but the difficulty lies in the selection of PI controller parameters; Literature [5] uses a space vector modulation technique, and abandons the switch table in the traditional direct torque control system, enabling the inverter switching frequency approximately constant.
(1) Ignore the space harmonics, the magnetic motive force generated by every phase current is sinusoidal distribution in space;
(2) Measurements of a rotor are converted to a stator, so that the stator and rotor windings have equal number of turns;
Abstract:Aimed at the problems of larger torque ripple and unconstant inverter switch frequency in the direct torque control for asynchronous motor this paper puts forward a control scheme which combined sliding mode variable structure theory with Space Vector PWM technology (SVPWM) to reduce torque ripple and keep switch frequency constant. The sliding mode variable structure controller is designed based on flux error and torque error, to make the torque and flux fast and accurate adjustment, controller outputs get inverter switch pulse signal by implementing SVPWM modulation which realized the constant frequency inverter switch. The simulation results showed the effectiveness of the proposed scheme.
Sliding mode variable structure control has the advantages of fast response, stronger robustness when facing the change of system parameters and external interference, it has been introduced to the asynchronous
In the field of AC drive, direct torque control (DTC) is a new control strategy after vector control. The direct torque control of asynchronous motors largely overcome these characteristics about computational complexity and the impact of vulnerability parameter changes, has become the second qualitative leap of speed control theory for exchange. Although traditional direct torque control has some advantages, such as simple control structure, rapid response, stronger robustness when there are parameters perturbations and external disturbances, etc, some questions are still exist in large torque ripple and the inverter switching frequency is not constant and so on[1,2].
(3) Ignore the magnetic saturation core loss, so that magnetic circuit can be expressed with a circuit in the form;
(4) Ignore the frequency and temperature's effects on the winding resistance;
Research on the Direct Torque Control for Asynchronous Motor Based on the Sliding Mode Variable Structure Control
Wei Jianhong, Li Xiaoqian, Zheng Yan
School of Information Science & Engineering, Northeastern University, Shenyang 110819, China. E-mail: zhengyan1@
此项工作得到国家自然科学基金资助, 项目批准号: 61174073
motor's direct torque control in recent years[6-8], to improve system robustness and the speed of response, to reduce the torque ripple and to keep switching frequency constant. This paper studies asynchronous motor's direct torque control problem which is based on sliding mode variable structure. Aimed at the problems of larger torque ripple and unconstant inverter switch frequency in the direct torque control for asynchronous motor, this paper puts forward a control scheme which combined sliding mode variable structure theory with Space Vector PWM technology (SVPWM) to reduce torque ripple and keeps switch frequency constant. The sliding mode variable structure controller is designed based on flux error and torque error, to make the torque and flux fast and accurate adjustment, controller outputs get inverter switch pulse signal by implementing SVPWM modulation which realized the constant frequency inverter switch. In order to reduce the steady-state error of the speed and improve control accuracy, the paper also designed a speed regulator based on sliding mode variable structure control, compared with the conventional PI control, system's response speed has been improved and steady-state error has been reduced.
Key Words: Asynchronous motors, Sliding mode variable structure control, Direct torque control, Torque ripple, Space vector PWM technology
1 INTRODUCTION
The research about reduces the torque ripple of induction motor's direct torque control system and keeps switching frequency constant has been the focus of attention and studied by some scholars at home and abroad. Literature [3] proposed a control scheme based on the duty cycle modulation technique which does not use conventional torque hysteresis comparator, it calculated the time through using mathematical sampling period in a non-zero voltage vector and the respective roles of the zero voltage vector, the simulation method enables the switching frequency approximately constant; Literature [4] designs a torque and flux controller to reduce torque ripple which is PI-based, the simulation results show that the solution reduce the torque ripple in some extent, but the difficulty lies in the selection of PI controller parameters; Literature [5] uses a space vector modulation technique, and abandons the switch table in the traditional direct torque control system, enabling the inverter switching frequency approximately constant.
(1) Ignore the space harmonics, the magnetic motive force generated by every phase current is sinusoidal distribution in space;
(2) Measurements of a rotor are converted to a stator, so that the stator and rotor windings have equal number of turns;
Abstract:Aimed at the problems of larger torque ripple and unconstant inverter switch frequency in the direct torque control for asynchronous motor this paper puts forward a control scheme which combined sliding mode variable structure theory with Space Vector PWM technology (SVPWM) to reduce torque ripple and keep switch frequency constant. The sliding mode variable structure controller is designed based on flux error and torque error, to make the torque and flux fast and accurate adjustment, controller outputs get inverter switch pulse signal by implementing SVPWM modulation which realized the constant frequency inverter switch. The simulation results showed the effectiveness of the proposed scheme.
Sliding mode variable structure control has the advantages of fast response, stronger robustness when facing the change of system parameters and external interference, it has been introduced to the asynchronous
In the field of AC drive, direct torque control (DTC) is a new control strategy after vector control. The direct torque control of asynchronous motors largely overcome these characteristics about computational complexity and the impact of vulnerability parameter changes, has become the second qualitative leap of speed control theory for exchange. Although traditional direct torque control has some advantages, such as simple control structure, rapid response, stronger robustness when there are parameters perturbations and external disturbances, etc, some questions are still exist in large torque ripple and the inverter switching frequency is not constant and so on[1,2].