Inductances and resistance measurement of a permanent magnet synchronous motor

This paper proposes an approach to the measurement of the inductances and the resistance of a PMSM without any fixture to lock the rotor. It was announced that the measurement of the inductances and the resistance should be carried out by the locked-rotor test, i.e., the rotor was fixed with a fixture to avoid the swing of the PMSM. The proposed method of this paper uses a biased sinusoidal current to excite only one phase of the PMSM such that the motor is in standstill. Under such a condition, the inductances and the resistance are simply related to the phasors of the voltage and the current. The salient feature of this method is a technique to maintain the motor at standstill. The stability condition for the standstill of the PMSM is studied by Lyapunov stability theory. Some experiments verify the theory and demonstrate the powerfulness of this method.