Complex Frequency-Domain Analysis of Inverter-Fed Induction Machines

An equivalent circuit of an induction machine in complex frequency domain is presented. This can be used to predetermine the performance of induction machine supplied with balanced nonsinusoidal voltages without obtaining the harmonic components of the supply voltage waveform as in classical approach. Moreover, a transfer admittance function has been defined between the line current and the line voltage of an induction machine with star- or delta-connected stator windings. The speed of the machine has been assumed to be constant to ``linearize´´ the system. The admittance function has been used to obtain the waveform of stator line current for a given line voltage waveform using fast Fourier transforms. The waveforms obtained using this method have been compared with the waveforms obtained in experimental investigations reported earlier. The two are in excellent agreement.