One-Cycle Control for a Double-Input DC/DC Converter

In hybrid power systems, the use of a multiple-input converter (MIC) instead of several single-input converters leads to a simpler circuit and lower cost. Energy management is always required for the MICs in order to ensure the highest utilization of renewable energy. The MIC-based hybrid power system is a typical multiple-input multiple-output coupling system, and it has multiple operating modes. As a result, the design of the controllers is very complicated. This paper proposes one-cycle control (OCC) for double-input buck converter (DIBC) to eliminate the interactions of the control loops and, thus, to simplify the design of the controllers. The mode transition circuit is further proposed to realize seamless mode transition, according to the available renewable energy and the output power. Small signal models of DIBC in different operating modes are derived. It can be seen that with OCC, the two control loops are independent of each other, and no current regulator is required. Moreover, the design conditions of the output voltage regulator in different operating modes are the same. As a result, the controller design is greatly simplified. An 800-W prototype has been built and tested in the lab and the experimental results validate the proposed OCC.