PERMANENT MAGNET SYNCHRONOUS MOTOR DRIVE SYSTEM

Abstract

The modern high quality magnets have made compact motor designs possible. To• gether with the rapid achievements in the performance of microcontrollers and power electronics, permanent magnet AC motor drives have become competitive in increas• ing numbers of applications, both in servo drives and other industrial applications as well. These motors are used mainly where they may replace traditionally brushed electrically or permanent. magnet excited DC motor drives, but it is also a competitor to induction motor and reluctance motor in several applications. The control of a high performance PMSM drive for general industry applications has received wide spread research interests. In this thesis, a complete permanent magnet synchronous motor (PMSM) drive system is developed. Dynamic performance of the system is studied under different types of current controllers of voltage-source inverter. In this study, state space mathematical model of the motor, speed controller and the inverter in the d-q axis is devised. The nonlinear dynamic model of the PMSM is, effectively, converted to a linear model with the aid of the vector control principle. Based on this linear model, performance predication with the conventional and proposed speed controllers, is assessed. A novel current controller is introduced. This controller is a combination of hysteresis controller, to cater for high speed, and a modified ramp comparator controller, for low speed, operations. Hardware of this control system is implemented using digital signal processor (DSP) board. The software algorithms of the drive system are developed. The on-line implementation of these algorithms is accomplished on an experimental set up.