Stator Inductance Estimation for Permanent Magnet Motors Using the PWM Excitation

The permanent-magnet (PM) motors are widely used in many industrial drives. Accurate knowledge of machine parameters, such as inductance is essential for efficient and optimal control of the machine. There are numerous methods proposed in the literature for online as well as off line learning of machine parameters. They differ in accuracy and measurement techniques. This paper proposes an online measurement of inductance using the relationship between derivative of current with respect to time and flux linkage. An adaptive observer is used to calculate the inductance parameters from the current measured. The proposed method uses no external injection but relies on the PWM excitation used for normal motor drive control. The simulation and experimental results show the feasibility and performance of the proposed technique.