Inductance measurement of doubly salient permanent magnet motors

The inductance characteristic of a doubly salient permanent magnet (DSPM) motor is the basis of design, analysis and control of the motor. Due to the nonlinear operation and doubly salient structure of the motor, this characteristic is a function of not only the rotor position, but also the strengthening and weakening actions of the armature flux to the PM flux, making the measurement of inductance difficult. This paper aims to propose new methods for the measurement of the motor inductance for any rotor positions and level of excitation. The proposed method is applied to the two newly developed DSPM motors and the results are compared with those obtained by finite element analysis. It is shown that the proposed method can effectively reflect the influence of the strengthening and weakening actions of the armature flux to the PM flux on the inductance of the DSPM motors.