Offline method for determination of non-linear dependence of machine magnetising inductance utilising parallel operation of current and voltage model

The simplest mathematical models of the induction motor (IM) use the presumption of the machine's linear magnetising characteristics. However, this may hold only in a limited operating range of the electric drive. It is well known that the magnetising inductance saturates as a function of the magnetising current due to the non-linear properties of the magnetic circuit. However, this is not the only type of saturation. Depending on the design of the rotor, the machine's magnetising and leakage inductances may also saturate as a function of the rotor current. A new experimental method is proposed here. It identifies the dependence of the T equivalent circuit magnetising inductance on the rotor flux and torque producing current component using parallel operation of the so-called current and voltage model of the IM.