Spectral composition of input voltage of the asynchronous drive with valve cascade converter

Nowadays, a controlled electric drives (ED) are widely used in different fields of industry. Well-known that about 10 per cent of all electric power is consumed by controlled ED. In an asynchronous drive with valve cascade converter-asynchronous-valve cascade (AVC), the smooth start and speed control of the phase-wound rotor motor are realised. However, the frequency converter as a part of electric drive can have adverse effect on the supply network. Therefore, the problems with applying AVC are possible. This article presents the results of modeling and analysis of AVC in MATLAB environment. The proposed model can be used to investigate different characteristics of AVC as well as influence of circuitry parameters on the power quality indices of supply network. The input voltage spectra based on the application of fast Fourier transform to simulated waveforms are provided. Results of simulation show that in addition to the higher harmonics, spectra contain interharmonics. It was concluded that ignoring of interharmonics in estimation of total harmonic distortion causes significant inaccuracy. This can lead to problems with eliminating the harmonic distortion.