Full Speed Range Hybrid Sensorless Control of Permanent Magnet Synchronous Motor Based on Weighting Dual EKF and Signal Injection

In the field of speed sensorless control of permanent magnet synchronous motors, it is difficult to accurately estimate the speed via a single algorithm for full speed range because there are many non-ideal factors when the algorithms are realized. In this paper, high frequency pulse signal injection method is applied in the low speed region, and dual EKF is used in the medium and high speed region. The switching of these two algorithms is achieved by the weighted averaging rule. This hybrid estimation strategy avoids detecting the back-electromotive force which is hard to be measured in low-speed region, and also avoids the adverse effects of the filter delay in the mid-high speed region. Therefore, it enables the sensorless control effective over the full speed range. Moreover, the dual EKF algorithm can estimate the motor parameters with a relatively small amount of calculation. Validity and effectiveness of the proposed scheme is shown in the simulation results.