ABSTRACT
The rotor position is sensed with an optical encoder or a resolver for high-performance applications. The position sensors cost as much as a low-power motor, thus making the total system cost very noncompetitive compared to other types of motor drives. The control and operation of permanent magnet synchronous machine drive without a rotor position sensor would enhance its applicability to many other cost-sensitive applications and to provide a backup control in sensor-based drives during sensor failures. The input of initial values of speed and rotor position serves to help the transition process from initial starting to estimation process for continued operation and control. To implement such a sensing strategy, the injected signal is a high-frequency sinusoid in the estimated rotor reference frames. The rotor reference q- and d-axes, which constitute the rotor reference frames, are away from the corresponding stator q- and d-axes by the rotor position and these axes constitute the stator reference frames.
