Seamless transition of the operating zones for the extended-Duty-Ratio boost converter

An extended-duty-ratio (EDR) boost is a unique combination of interleaved, multiphase boost converter and switched capacitor configuration that achieves a high converter gain without increased switching losses as most of the switches experience only fractions of the output voltage depending on the number of phases M. For an M-phase EDR converter with different combinations of the operating modes, M operating zones can be identified, with each zone having distinct converter gain and current sharing properties. Inherent current sharing is possible in only one operating zone ((M − 1)/M ≤ D ≤ 1), whereas, the duty ratio modification is required to ensure the same for other operating zones. This duty ratio adjustment is unique in each zone with varying phase shift of the carrier signal. The adjustment scheme also affects the converter gain, thus making the operating zone transition a complex assignment. A controller has been designed to detect the zone transition and ensuring a smooth transition of the operating zones for a 3-phase EDR boost converter. The proposed concept is validated with simulation and experimental results from a 250 W, 3-phase EDR boost, GaN-based hardware prototype.