Investigation of multiple-input converters bi-directional power flow characteristics

This paper analyses the composition and structure of five multiple-input converter (MIC) families, and then identifies possible bi-directional applications for these MIC families. Among these five MIC families, the bi-directional power flow capability of pulsating voltage source cell MICs, push-pull connected MICs, and time-sharing (TS) MICs were not identified in past works. In particular, TS-MICs are originally considered unidirectional. With a new driving strategy and components arrangement, TS-MICs can also perform bi-directional operations. The operation states of a bi-directional TS-MIC are analyzed and the voltage transfer ratios (VTRs) are derived. A prototype of TS dual-input SEPIC is built to verify the bi-directional operation analysis. The measured VTRs match with the prediction in the analysis, and both input cells simultaneously change their input current direction when the operation status changes between discharge-mode and charge-mode.