The intention of this work is to introduce a new method for measuring the induction motor parameters by the help of a standard PWM-frequency converter, and to compare the results with those from a variable frequency test with sinusoidal voltage and also with a variable speed test. The purpose of measuring parameters of a deep bar motor is to design suitable equivalent circuits and mathematical models that take skin effect and saturation into account. Only in particular cases the T-parameter's variation with frequency and current are given by the manufacturer, in most cases the customer has to find a method to determine them.
The method is discussed on the base of the motor's equivalent circuit for harmonic voltage components when a non-sinusoidal voltage is impressed, and losses, saturation and skin effect are taken into account. The variable frequency test with inverter supply has been performed on different motors and by inverters of different design. Measurements in the laboratory show good agreement between inverter supply tests and variable speed- and sinusoidal voltage tests. The rotor impedance calculated from inverter tests is practically the same as for the sinusoidal voltage or variable speed test, provided the fundamental values of voltages, currents and powers are used in the calculations.
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