Spectral analysis of DC link ripple currents in three-phase AC/DC/AC PWM converters feeding AC machines

摘要

In this paper, DC link ripple currents for three-phase AC/DC/AC PWM converters feeding adjustable speed AC machine drives are analysed in a frequency domain. The expression of the harmonic currents is developed by using switching functions and exponential Fourier series expansion. The effect of the displacement angle between the switching periods of line-side converters and motor-side inverters on the DC link ripple currents is investigated. Also, the influence of asynchronization of PWM is observed. The result of analysis is compared with frequency spectrum which results from PSIM simulation.