Special Issue Article Open Access

Optimal Design of a Multi-Level Modular Capacitor-Clamped Dc-Dc Converter

Abstract

Magnetic-less multilevel dc–dc converters attract much attention in automotive industry due to their small size, high efficiency, and high temperature operation features. A multilevel modular capacitor-clamped dc–dc converter (MMCCC) is one of the most promising topologies among them with simple control and reduced switch current stress. This paper presents a quasi-resonant technique for multi-level modular switched capacitor dc-dc converter (MMSCC) to achieve zero current switching (ZCS) without increasing cost and Sacrificing reliability. In order to design the converter with the highest efficiency, the analytical power loss equation of an MMCCC should be derived. Also, by considering the stray inductance in the circuit, the optimal design approach should be divided into two cases, over damped case and under damped case. The converter can be designed to achieve high efficiency in both cases by varying circuit parameters. If the circuit is designed in over damped case, huge electrolytic capacitor bank has to be used whereas in under damped cases mall-size multilayer ceramic capacitor can be utilized due to the low capacitance requirement. This ZCS-MMSCC employs the stray inductance distributed in the circuit as the resonant inductor to resonate with the capacitor and provide low dv/dt and di/dt switching transition for the device. The ZCSMMSCC does not utilize any additional components to achieve ZCS, and meanwhile solves the current and voltage spike problem during the switching transition, thus leading to reliable and high efficiency advantages over traditional MMSCC. Furthermore, the ZCS-MMSCC reduces the capacitance needed in the circuit to attain high efficiency. In this case, the bulky capacitor bank with high capacitance in traditional MMSCC to reduce voltage difference and achieve high efficiency is not necessary any more.

Sujith K, Eldhose K A, Babu Paul

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