An optimized I-F startup method for BEMF-based sensorless control of SPMSM

BEMF-based methods, with the purpose of estimating the position and speed of the permanent magnet synchronous machine (PMSM), cannot be applied in low- speed range. Though the high frequency injection (HFI) methods can be operated in low- speed range, they are complicated. For low cost SPMSM applications, it is not necessary to be operated in low- speed range. Thus, an I-f starting method was introduced to accelerate the machine to a desired speed. This paper proposes an optimized starting procedure for sensorless control of SPMSM. The proposed transition procedure, including a nonlinear current reduction function, allows a more smooth transition between the startup accelerating mode (low- speed range) and the back-EMF-based sensorless control mode (medium- and high- speed range). The simulation results verify the effectiveness and robustness of the proposed method.