Design and digital hardware implementation of a sensorless controller for PMSM drives using LF signal injection and EKF

To obtain a wide-speed range control from a standstill to a high speed region, combining the approaches - LF (Low Frequency) signal injection and EKF (Extended Kalman Filter) in sensorless PMSM drive is proposed in this paper. The LF signal injection algorithm is applied to the startup and low-speed mode for the SPMSM; then it will transfer to the medium or high speed mode using the EKF algorithm. The LF signal injection algorithm doesn't need to consider the issue of “saturation saliency”; therefore it is very suitable for surface PMSM. Further, it also prevent from the sound-noise problem. In addition, the EKF is basically a full-order stochastic observer for the recursive optimum state estimation of a nonlinear dynamic system in real time by using signals that are in noisy environment. In this paper, the mathematical modelling of PMSM and the rotor position estimation algorithms of LF signal injection and EKF are firstly derived. Secondly, a Very high speed IC Hardware Description Language (VHDL) is presented to describe the behavior of the adopted estimation algorithm. Thirdly, to verify the correctness of the designed VHDL code of the estimation algorithm, based on Electronic Design Automation (EDA) simulator link, a co-simulation work is constructed by Simulink and ModelSim. Finally, some simulation results verify the correctness of the proposed hybrid approaches using LF signal injection and EKF for the sensorless PMSM speed control system.