A Novel Sensorless Initial Position Estimation and Startup Method

In this article, a low noise and simple initial position estimation and startup method based on high-frequency rotating sinusoidal voltage injection is proposed for interior permanent magnet synchronous machine. Different from the conventional method that uses negative sequence current and closed-loop position observer, the proposed method simply compares the three-phase high-frequency current amplitudes calculated by discrete Fourier transform to detect the rotor sector. The initial position can be obtained within only half of the injection cycle without parameter tuning. Thus, it is fast and simple compared to the conventional method. Both discrete and continuous rotor positions can be obtained and used for startup. Furthermore, to mitigate the acoustic noise during starting, a multifrequency injection strategy is introduced to reduce the noise emission caused by high-frequency voltage injection. Experiments are carried out to verify the effectiveness of the proposed method.