Predicting fast-scale instabilities in switching power converters:: a ripple-based unified perspective

This paper presents a re-examination of conditions for lost of period-1 bifurcation appearance in switching power converters. A unified index based on the ripple level in the PWM modulator is able to predict first occurrence of fast-scale instability. Previous parametric design space explorations have been presented to explore the rich complex behaviour phenomena in switching power converters. The bifurcation-avoiding design-oriented index presented herein allows the designer to collect in a unified index the effect of several circuit parameters, such as input and output voltage, reactive component values and switching frequency, together with feedback parameters. The approach is validated through time domain simulations and bifurcation diagrams for a basic proportional voltage feedback PWM buck converter. Alternative topologies such as multilevel converters and interleaved parallel-connected converters, as well as more practical control methods such dynamic compensators, current-mode control, and hysteretic control are discussed as well. Proof-of-concept experimental results are reported to demonstrate the approach.