Position Sensorless PMSM Drive System Including Square-Wave Operation at High-Speed

This paper proposes the position sensorless drive system for PMSM, in which the inverter is controlled by a six- step square-wave operation at high speed in order to increase the torque and power at high speed region and expand the operating range. The speed and position are estimated based on the estimation of an extended electromotive force, and the sensorless control is achieved not only in the current vector control region by the sinusoidal PWM of inverter but also in the voltage phase angle control region by the square-wave operation. The performance of the proposed drive system is evaluated by the experimental results.