Very Low Speed Sensorless Vector Control of Synchronous Reluctance Motors with a Novel Startup Scheme

In this paper a very low speed sensorless vector control of synchronous reluctance motor with a novel startup scheme is presented. The estimation of speed and rotor angle is based on extended programmable cascaded low pass filter (EPCLPF) which reduces the dc-offset effect at low speed area effectively. Thus the sensorless control at very low speed area is possible. At startup condition, the rotor angle is assumed rotating at synchronous speed, and because the estimation rotor angle is valid at very low speed, its error decreases rapidly after the initial rotor movement. Thus motor start up without torque jerk is achieved. The experimental results, which are done by a RT-Linux pc based system, show the estimated and the actual rotor angle at very low speed region are agreed and sensorless vector control is achieved at very low speed area as well as high speed. Also the motor startup at standstill condition is possible.