Field oriented control CSI synchronous motor drive without shaft sensors

This paper presents a high performance CSI-fed synchronous motor drive without using shaft sensors. The control algorithm is based on the estimated stator flux from the measured voltages and currents. A modified integrator suitable for AC drives is proposed in this paper, based on which the magnitude and position of the motor flux can be accurately determined even at very low motor speeds. A prototype with a DSP controller has been built to drive a 6 poles, 6 HP synchronous motor. The experimental results show that the drive system has a fast dynamic response during motor startup and speed reversal. The proposed drive can operate over a wide speed range from its rated value down to 10 rpm.