Current zero cross detection-based position sensorless control of synchronous reluctance motors

This paper presents a novel position sensorless control method of synchronous reluctance motors (SynRM) for low cost variable speed drives in automotive applications. In the proposed scheme, the controller outputs the voltage RMS value and its lead angle as a pair of control commands which realizes the maximum torque/ampere ratio operation of the motor for the given operating conditions. The proposed method is focused on an error between the detected power factor angle at current zero cross point in the controller and the experimentally modeled power factor angle. For the above position estimation algorithm, it is analytically cleared that SynRM have a helpful behavior contributing for the stability improvement of the position sensorless control. The experimental studies using 4-pole SynRM with multi-flux barrier rotor show that the proposed scheme realizes the stable sensorless control for the variable speed operation including starting.