Generalized Averaging Method for Power Electronics Modeling from DC to above Half the Switching Frequency

TL;DR

This paper introduces a generalized averaging method using moving Fourier coefficients to accurately model power electronic converters at frequencies near or above half the switching frequency, overcoming previous limitations.

Contribution

The paper develops a novel generalized averaging approach that extends modeling capabilities beyond half the switching frequency for various switching signals in power electronics.

Findings

Higher modeling accuracy near and above half the switching frequency.

Validated models on different converters show improved precision.

Applicable to nearly all power electronic converter types.

Abstract

Modeling power electronic converters at frequencies close to or above half the switching frequency has been difficult due to the time-variant and discontinuous switching actions. This paper uses the properties of moving Fourier coefficients to develop the generalized averaging method, breaking though the limit of half the switching frequency. The paper also proposes the generalized average model for various switching signals, including pulse-width modulation (PWM), phase-shift modulation, pulse-frequency modulation (PFM), and state-dependent switching signals, so that circuits and modulators/controllers can be modeled separately and combined flexibly. Using the Laplace transform of moving Fourier coefficients, the coupling of signals and their sidebands at different frequencies is clearly described as the coupling of moving Fourier coefficients at the same frequency in a linear time-invariant system framework. The modeling method is applied to a PWM controlled boost converter, a V2 constant on-time controlled buck converter, and a PFM controlled LLC converter, for demonstration and validation. Experimental results of the converters in different operating modes show that the proposed models have higher accuracy than exiting models, especially in the frequency range close to or above half the switching frequency. The developed method can be applied to almost all types of power electronic converters.