Power profile based selection and operation optimization of parallel-connected power converter combinations

Abstract

Many electrical sources and loads are operating at different power levels, partly with full and partly with only a small percentage of their rated power (e.g. photovoltaic systems, elevators or electric heaters). For such devices the connection to the grid can be more efficient with several parallel-connected converters instead of a larger single one. A system of parallel-connected converters facilitates the potential to increase the overall efficiency of the system, either by the selection of different topologies and switching devices of the particular converters or by different operating strategies to split the power between the single converters. This paper presents a method to optimize the operating strategy of such systems with different parallel-operating converters, including the optimal choice of an arrangement based on a specific power demand profile. These two topics sound different but the optimal converter combination can only be selected if the most efficient operation strategy is available. Therefore these topics are interrelated.