Issues related to interharmonics

Some of the most remarkable issues related to interharmonic modelling and simulation are presented. Starting from the basic mathematical aspects, attention is firstly devoted to interharmonic frequency and amplitude variability. Then, the extension of the classical models developed for harmonic modelling to include interharmonics is discussed with particular attention to the problem of the frequency resolution and of the computational burden. Numerical results for all the issues presented are given with reference to case-studies constituted by two popular schemes of adjustable speed drives.