One-Cycle Control For Double-Input Buck Converter

In hybrid power systems, the use of a multiple-input converter (MIC) instead of several single-input converters leads to simpler circuit and lower cost. The energy management is always required for the MICs to make the most utilization of renewable energy. So, the MIC-based hybrid power system is a typical multiple-input multiple-output (MIMO) 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 the double-input buck converter (DIBC) to eliminate the interactions of the control loops and thus to simplify the design of the controller.In the thesis, the operating principle and the operating modes of the DIBC are analyzed. Then the implementation of the OCC for the DIBC under different operating modes is proposed, and the mode transfering circuit is further proposed to realize seamless mode transition, according to available renewable energy and the output power.In order to minimize the inductor current ripple, this thesis discusses the relationship between the inductor current ripple and the phase difference among the drive signals of the two switches, and an interleaved dual-edge modulation is proposed. And then the implementation of the interleaved dual-edge modulation for OCC is proposed.Small signal models of DIBC with conventional linear feedback control technique and OCC are derived for the control design in this thesis. It is shown that, with conventional linear feedback control technique, the output voltage loop and the input current loop are coupled each other; and with OCC, the two control loops are independent 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 control design is greatly simplified.An 800 W prototype has been built and tested in the lab. The experimental results verify the effectiveness of the proposed OCC and interleaved dual-edge modulation.