Frequency response power function of PWM DC/DC converter. I

Frequency response characterization is a principal tool for sensitivity analysis of an open loop and closed loop stable system. The small signal average and classical sampled-data models are suitable ways of measuring the sensitivity of a converter system at low frequencies. However they are not a suitable means of characterizing a system when there is a significant amplitude of ripple in the system output and also the validity of the model is limited to half of the sampling frequency. After an introduction to the notion of frequency response of a lifted system, we introduce the idea of frequency response power function for the time lifted system. The frequency response power function provides an extended means to characterize a system with large ripples. We then develop the expressions for estimating the frequency response power function of an open and closed loop converter system. Several examples have been given to demonstrate the advantages of the present notion of frequency response power function.