Evaluating the robustness of a sensorless controller for permanent magnet synchronous motor drives

A PMSM drive that does not require an encoder or some other direct rotor position sensor would be cheaper, require less space and possibly suffer from fewer mechanical reliability problems. In sensorless control, voltage and current measurements are used to estimate rotor position and speed. This paper evaluates the performance of a reduced order observer for PMSM rotor position estimation when applied in a closed loop configuration for speed control. The operation of the sensorless control strategy over a wide range of speed and load variation is presented and shown to be robust. Operation particularly at low speeds and under no load condition, where current measurements are difficult, is also presented in this paper