Wide-Speed-Range Sensorless Vector Control of Synchronous Reluctance Motors Based on Extended Programmable Cascaded Low-Pass Filters

This paper proposes a new sensorless vector control of a synchronous reluctance motor for a wide range of speeds. The estimation of speed and rotor angle is based on extended programmable cascaded low-pass filters (LPFs), which effectively reduce the effects of direct-current (dc) offsets at low speeds. The effect of the number of LPF stages on output dc offset, estimation accuracy, and dynamic performance are determined, and their equations are developed. The determination of the number of LPF stages is based on these developed equations. Because the estimate of the rotor angle near-zero speed is possible, the motor start-up procedure can be done without complexity. The experimental results show that the estimated and the actual rotor angles are in agreement at very low and high speeds. Thus, sensorless vector control can be achieved over a wide range of speeds. In addition, motor start-up in a standstill condition is possible, and the transient response at low and high speeds is acceptable.