| Abstract |
In a motor drive system, a voltage source converter with hard switches generate high dv/dt, which causes leakage currents due to stray capacitances of an electric motor. A high frequency model of an electric motor is an important issue for power electronic engineers, which helps them to analyze leakage and bearing currents and to design EMI filters. At low frequency, an equivalent circuit of an electric motor consists of inductances and resistances without considering stray capacitances and skin effect. These issues become more important at high frequency particularly for high speed switching applications due to high dv/dt. This paper presents a simple method to extract high frequency parameters of an electric motor. An impedance of a 5.5KW motor has been measured in terms of frequency using an impedance analyzer and the results have been used to extract high frequency parameters. It is recommended to estimate the behavior of the motor in a frequency range, when the motor acts as a capacitive or an inductive load according to the phase values of the impedance. Then, the parameters can be calculated directly from the magnitude and the phase values of the impedance. A simple model of an electric motor at high frequency used for high speed switching applications is discussed in this research work. |
