| Abstract |
The field oriented control of an induction motor has been widely used in high performance servo systems. As well known, it has two major problems; the system is complex and strongly sensitive to the motor parameters. The authors proposed the direct torque control and ultra-wide speed control of an induction motor. The direct torque control realized the torque response as high as 2(kHz) without a position sensor, and the ultra-wide speed control enable the motor to operate at l(rpd) by introducing the impulsive torque drive and using high loop gain which decreasing the lag time of the control circuit. In this paper, a combined approach of the two methods is presented. It makes possible both ultra-low speed control under l(rph) and high torque response corresponding to field oriented control. By adjusting the PI gain, the speed control range is obtained over 1:200000. Implementing with a digital signal processor (DSP 320C25), the control system is made very simple and free from adjustment of the circuit parameters. |
