In order to describe the generation of harmonics and interharmonics (that are defined as non-integer multiplies of fundamental or switching frequencies and have several different effects in power utility connected VSI systems compared to known harmonics) in generalized power converters, a new approach is proposed based on the “Non-Linear Modulator” concept in frequency-domain; and the analytical model is derived and discussed for commonly used control scheme of d-q reference frame. Afterwards, several effects of feedback control and compensation blocks are explained, analyzed and simulated. Moreover, experimental results are also provided to approve the validity of analysis and simulation.