Kalman filters unifying model-based and HF injection-based sensorless control of PMSM drives

Methods of sensorless control of PMSM drives are commonly divided into model-based and high-frequency injection based approaches. Each of these approaches uses a different algorithm for estimation of the rotor position and speed. Typically a Kalman filter is used for the model-based approach and phase-locked loop (PLL) for the hf injection based approach. In this paper, we show that the PLL is a steady state solution of the Kalman filter for a special state space model. Since this model has a commonly used state equations, we can easily combine the observation equations from the model-based approach with those from the hf injections. Several possibilities of combination are described and tested in the paper.We illustrate properties of these algorithms on experimental data in sensored mode. Sensorless control strategy based on the presented models is demonstrated on a laboratory prototype of surface mounted permanent magnet synchronous motor (PMSM) drive of rated power of 10.7kW.