Sensorless Control of Surface Mounted PMSM and BDCM with New Starting Technique

In this paper, an accurate method for sensorless control of permanent magnet brushless motors is explained. The method doesn´t include any modification to the classical construction of such motors and can be easily integrated within the drive electronics. It is applicable to both motor types, i.e. those with sinusoidal or trapezoidal back EMF.. The back EMF waveform is extracted on-line using simple algebraic expression through a newly proposed measurement setup. It is then used within the corrective phase of an extended Kalman filter (EKF). A method is proposed to detect rotor position at starting to enable maximum starting torque/ampere at the required direction of rotation. The method functionality is tested by simulation for both motor types. Simulation results show a good performance at very low speed.