Small signal model of Triangular Current Mode (TCM) operation for Bidirectional Source/Sink Buck and Boost Power Converters

This paper presents a small signal model for bidirectional source/sink buck and boost power converters operating in Triangular Current Mode (TCM) and controlled with a variable-width Hysteretic Current Mode Control (HCMC). The well-known current injected equivalent circuit approach (CIECA) has been applied to derive the canonical circuit. For the sake of simplicity, the resonant intervals during the dead-times have been obtained using a linear approximation. The theoretical small signal model has been validated using two different source/sink power converters: an 80 W synchronous buck converter from 48 V to 24 V and a 100 W synchronous boost converter from 24 V to 48 V. The transfer functions of this power converter have been measured using a Venable Frequency Response Analyzer (FRA6340) and compared to the theoretical ones.