Active Power Analysis of PWM-driven Induction Motor in Frequency Domain

Pulse-width-modulated (PWM) voltage source inverters (VSI) are a common way to drive induction motors in variable speed applications. As switching hardware improves, motors are driven with increasing switching frequencies, extending the frequency range of PWM harmonics. Discrete Fourier Transform (DFT) can be used to analyze the differences in the active power spectrum as switching frequency is changed. This paper covers the basic methodology on DFT-based analysis of input power measurements. Analysis on the input active power spectrum of a PWM VSI driven 5-kW induction motor is conducted at different switching frequencies.