High performance current sensorless speed servo system of PM motor based on current estimation

This paper proposes a new speed servo system of SPMSM (surface permanent magnet synchronous motor) without current sensor. This system is constructed by the current simulator of SPMSM, which is a software algorithm by DSP (digital signal processor). The sensor of the proposed system is only a position sensor such as a rotary encoder. The proposed speed servo system is simple and economical. Moreover, when SPMSM has parameter variations, the proposed current sensorless speed servo system keeps the stable speed response and has no steady state error. The experimental results point out that the proposed current sensorless speed servo system has the desired current response and the desired speed response. The actual current waveform of the proposed system is smooth and clean.