Duty phase shift technique for extended-duty-ratio boost converter for reducing device voltage stress over wider operating range

This paper proposes a modified duty phase shift technique for an M-phase extended-duty-ratio (EDR) boost converter to facilitate the inherent current sharing property and reduced voltage stress on the switching devices of the EDR converter over wider operating region. With conventional phase shift of (360/M)° among the operating phases, a reduced voltage stress and inherent current share between the interleaved boost phases is only possible for the operating region of duty ratio given by (M - 1)/M ≤ D ≤ 1, with a minimum gain of M². However, for a wide range of input-output application with the need of extended range of voltage conversion gain, the converter will operate over broader duty ratio range. With the proposed duty phase shift technique, the advantages of EDR converter of inherent current sharing and reduced voltage stress on the active devices can be restored over wider operating range allowing a minimum gain of 2 M. The method is validated with extensive simulation results from multi-phase EDR boost and experimental results from a 250 W 3-phase EDR boost with GaN-based hardware prototype operating at 200 kHz switching frequency.