Design-Time and Run-Time Minimization of Device Losses in a Wide-Range Composite DC-DC Converter

Optimization of power converters throughout their operating range is essential for wide-range applications, such as dc-dc conversion in hybrid and electric vehicles. This paper proposes the use of a two-module composite converter architecture configured in an input-parallel output-series arrangement for such a wide range of applications. An optimization algorithm is proposed to minimize the worst-case device loss across the entire operating range of the composite converter. The algorithm leads to the selection of design-time parameters, which are selected once and held constant across all operating points, and run-time variables, which adapt dynamically based on the operating conditions and chosen design-time parameters. For a given set of design-time parameters, the corresponding run-time variables are optimized to minimize overall device loss. The algorithm is applied to design and operate a composite converter over a wide input range of 150 V-500 V and output range of 300 V-900 V with power levels up to 40 kW. The proposed design and operation of the composite converter are verified using a hardware prototype demonstrating a peak efficiency of 98.8% at a load of 10 kW.