Start-Up and Dynamic Modeling of the Multilevel Modular Capacitor-Clamped Converter

Electr. & Comput. Eng. Dept., Univ. of Utah, Salt Lake City, UT, USA
IEEE Transactions on Power Electronics (Impact Factor: 6.01). 03/2010; 25(2):519 - 531. DOI: 10.1109/TPEL.2009.2025273
Source: IEEE Xplore


This paper will present the analytical proof of concept of the multilevel modular capacitor-clamped converter (MMCCC). The quantitative analysis of the charge transfer mechanism among the capacitors of the MMCCC explains the start-up and steady-state voltage balancing. Once these capacitor voltages are found for different time intervals, the start-up and steady-state voltages at various nodes of the MMCCC can be obtained. This analysis provides the necessary proof that explains the stable operation of the converter when a load is connected to the low-voltage side of the circuit. In addition, the analysis also shows how the LV side of the converter is (1/ N )th of the HV side excitation when the conversion ratio of the circuit is N . In addition to the analytical and simulation results, experimental results are included to support the analytical proof of concept.

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    • "Without any measurements or special control algorithms the capacitor voltages balance to the required values. This natural balancing mechanism was analyzed before in many papers, [7]–[13], mostly using frequency domain analysis. "
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    ABSTRACT: Magnetic-less multilevel dc-dc converter attracts much attention in automotive application due to its small size and high temperature operation features. Multilevel modular switched-capacitor dc-dc converter (MMSCC) is one of the most promising topologies among them with simple control and reduced switch current stress. This paper presents an optimal design method for MMSCC to achieve the highest efficiency with smallest size. In order to design the converter with the highest efficiency, the analytical power loss equation of MMSCC should be derived. By considering the stray inductance existing in the circuit, the optimal design point should be considered in two cases, over-damped and under-damped. The converter can be designed to achieve the highest efficiency in both cases. However, in under-damped case, small size multilayer ceramic capacitor can be utilized due to the low capacitance requirement. Although higher switching frequency is required in under- damped case due to practical considerations, zero current switching (ZCS) can be achieved for all the devices. Therefore, the optimal design point of MMSCC with the smallest size and the highest efficiency should be chosen at under-damped case with ZCS. Experimental results of designing MMSCC at under- damped case with ZCS are provided to demonstrate the validity of the proposed method.
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