Effective phase utilization and efficiency improvement of high power interleaved DC–DC converter using modified rotating phase shedding control

Abstract

The interleaved bidirectional DC–DC converters (IBC’s) have a poor efficiency profile at light load conditions because the switching and core losses are more dominant than conduction losses. A phase shedding control (PSC) approach is one of the methods for multi-phase IBC to maintain a good efficiency profile across all load circumstances. However, in a PSC of IBC, one phase remains active throughout the load change while the remaining phases only operate at the significant load change. This uneven utilization of phases causes the aging problem of over-exploited phase, which also may cause thermal instability and long-term reliability issues of the converter. This paper proposes an efficiency-based modified rotating phase-shedding control (MRPSC) algorithm for 3−ϕ IBC with an automatic phase selection to improve efficiency across all loading conditions and minimize the uneven aging effect in all phases by proper phase utilization. In addition, an auto-change inner loop-average current mode control (ACIL-ACMC) has been included in the proposed MRPSC algorithm to maintain equal current sharing and voltage regulations. The sampling and computational delay of ADC have also been considered for designing adequate inner and outer loop PI controllers of ACIL-ACMC. The proposed MRPSC algorithm has been implemented in the DSP (TMS320F28335) for 7.5kW IBC.