Online Stator Inductance Estimation for Permanent Magnet Motors Using PWM Excitation

The permanent-magnet motors are widely used especially in traction and power steering motor drive applications in automotive. Accurate knowledge of machine parameters, such as the 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 with the current derivative. 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 pulsewidth modulation excitation used for normal motor drive control. The simulation and experimental results show the feasibility and performance of the proposed technique.