Dead-time Compensation On SVPWM For PMSM System And Research On Speed Sensorless Control

With the fast development of modern AC motor control techniques, power electronics and microprocessors, permanent magnet synchronous machine (PMSM) drive systems are widely applied in industrial robots, electrical vehicles and household appliances. In order to improve the performance of the motor drive system, reduce the cost of hardware and satisfy the need of some certain circumstances, lots of attention has been given to dead-time compensation and sensorless control by the researchers of electrical machine control system.The main work of this thesis is concluded as two parts:first, this thesis presents a detailed analysis of the adverse effect that caused by the dead-time on the motor drive system. Then a dead-time compensation control scheme, which is based on the extended state observer (ESO), is proposed. Simulations and experiments are carried out to verify the effectiveness of the proposed control scheme. In the meanwhile, the existing sensorless control techniques are analyzed and studied in this thesis. Also, a new sensorless control method that based on the control of power factor angle is proposed. And experiments are conducted on a top-load washing machine.In the beginning, this thesis gives a brief introduction of the development of AC motor drive systems as well as the existing techniques of dead-time compensation and sensorless control. Then a detailed analysis of the mathematical model of PMSM is provided, which is followed by a brief introduction of the two main basic control strategies of PMSM. Also, the reason of imposing dead-time on the inverter and its adverse effect are discussed systematically, based on which an equivalent mathematical model of dead-time is presented. Then a dead-time compensation control scheme, which is based on the ESO, is proposed. In order to validate the effectiveness of the proposed control scheme, simulations and experiments are carried out on MATLAB/SIMULINK and a servo system respectively. The results show that the proposed control scheme has a better inhibition of the dead-time effect compared with the PI control scheme. In the meantime, this thesis gives a study of the two main sensorless control methods, which are methods based on back EMF and methods based on high frequency carrier injection respectively. And some typical sensorless control schemes are analyzed in detail, which includes open-loop estimate method based on mathematical model of motor, closed-loop estimate method based on sliding mode observer and pulsating voltage injection method based on saliency. In the end, a new sensorless control scheme that based on the control of power factor angle is proposed and experiments are implemented on a top-load washing machine to verify its effectiveness. Meanwhile, a practical rotor position estimator is also proposed for the closed-loop operation.