High frequency signal injection method is the most available method to achieve low speed and zero speed operations in mechanical sensor-less control of PMSM. The difficulty in HF signal injection method is how to pick up the HF components from the measured currents. Kalman filter is an adaptive filter and has been widely used in signal detections and processing. In this paper, a HF signal injection method using fuzzy Kalman filter for signal processing is proposed to realize the low speed operation in mechanical sensor-less control of PMSM. The Kalman filtering algorithm combined with a fuzzy inference system can efficiently adjust the covariance matrix of system measurement noise. Simulations and experiments are performed on PMSM, the results show that this method is a simple and direct signal processing method for HF signal injection method with very good stability and precision.
