Variable-Frequency Controlled Interleaved Boost Converter

Efficiency over the entire power range is an important performance metric for traction applications since electric vehicles (EVs) operate at very different power levels, in particular, lower power levels are more common for city driving. DC-DC converters operated under conventional pulse-width modulation (PWM) techniques at constant switching frequency experience significantly lower efficiencies at low power levels. To cope with this issue, this work addresses a bidirectional discontinuous-conduction mode (DCM) and variable-frequency control strategy for a three-phase interleaved boost converter to provide an improvement of the system efficiency at low power levels. The validity and effectiveness of the proposed approach are demonstrated by both simulation and experimental results on a 10-kW prototype.