Abstract
This paper presents a zero-voltage and zero-current switching (ZVZCS) capacitor-clamped half bridge (HB) three-level dc-dc converter (TLDC), which is well fit for high input voltage dc-dc industrial applications. The maximum voltage stress of the primary switches is limited by the flying capacitor and input capacitors, which is very close to Vin/2. Two unsymmetrical bidirectional switches are used to replace two of the primary switches in a conventional capacitor-clamped HB TLDC, which ensure ZVZCS of the main switches in wide load range. The reverse direction MOSFETs in the unsymmetrical bidirectional switches have low on-state resistance and are controlled with soft-switching mode irrelevant to the load current. Therefore, the additional power loss can be omitted. The current of the flying capacitor is greatly reduced due to ZVZCS operation, which would result in a smaller volume flying capacitor and high system reliability. Furthermore, the current imbalance problem of the power devices is also well solved. The circuit, basic operation principles and some important technical analyses are discussed in this paper, and experimental results from a 1-kW prototype are provided to evaluate the proposed converter.
Highlights
Three-level (TL) dc-dc converters (TLDCs) can be widely used in plenty of existing and upcoming industrial applications, e.g., dc-dc converters for distributed power systems, micro-grids, renewable energy power systems, and electric vehicles [1,2,3,4]
The most outstanding attribute of three-level dc-dc converter (TLDC) is reduced voltage stress of the primary switches, and both dynamic and static voltages on the main switches can be confined below Vin /2 by the clamping devices, such as clamping diodes or capacitors
A secondary active reset zero-voltage and zero-current switching (ZVZCS) TLDC was reported in Reference [6], wherein an extra capacitor is added to the primary side to realize a phase-shift (PS) switching scheme
Summary
Three-level (TL) dc-dc converters (TLDCs) can be widely used in plenty of existing and upcoming industrial applications, e.g., dc-dc converters for distributed power systems, micro-grids, renewable energy power systems, and electric vehicles [1,2,3,4]. A secondary active reset zero-voltage and zero-current switching (ZVZCS) TLDC was reported in Reference [6], wherein an extra capacitor is added to the primary side to realize a phase-shift (PS) switching scheme. Other to TLDCs with reduced volume of the output filter were which has the minimum primary switches generate a TL secondary-rectified waveform [18]. Q and Q cannot achieve minimize the voltage ripple on it, which increases the volume of Css. Q11 and Q33 cannot achieve zero-voltage switching in a wide load range due to less energy reserved in Llk. New capacitor-clamped zero-voltage switching in a wide load range due to less energy reserved in Llk. New capacitorTLDC without the above-mentioned drawbacks is an interesting problem. This paper proposes a novel ZVZCS capacitor-clamped HB TLDC, which overcomes all abovementioned shortcomings.
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