Modelling of AC/DC/AC conversion systems with PWM inverter

Modelling of AC/DC/AC power conversion systems with PWM inverters is considered and a new model is presented and discussed. The new model is based on the modulation function theory and uses the iterative harmonic and interharmonic analysis (IHIA), taking advantage of a new inverter model. The proposed model can be applied successfully to adjustable speed drives (ASD) for asynchronous motors, achieving better modelling accuracy with respect to approaches based on simplified inverter modelling. It also allows sensible reduction of computational burdens with respect to the time domain models. For this reason, it constitutes an attractive tool inside Monte Carlo simulations for the probabilistic analysis of harmonic and interharmonic distortion. Numerical experiments demonstrate the good performances of the proposed method and the need of accounting for the presence of interharmonics for high power PWM drives.