Sensorless operation of permanent magnet AC (PMAC) motors with modified stator windings

A sensorless field oriented control scheme for permanent magnet AC (PMAC) motor with split phase stator windings is presented. This motor is obtained by splitting the phase windings of a conventional three phase motor. The six-phase motor, however, is run as a three-phase motor by connecting the split phase stator windings in series, while the taps are made available for voltage measurements. By measuring the terminal voltages and the line currents, absolute position of the permanent magnet AC motor driven by a current regulated PWM inverter with a hysteresis controller is estimated. The estimated position information is independent of the stator resistance, thus this scheme is even applicable at low speeds. Simulation results are presented to show the effectiveness of the new controller, and it is shown that the position error is negligible.