Novel Bidirectional Three-Switch Single-Stage Single-Phase AC-DC Buck-Boost Converter With Ground-Referenced Output
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2025-06
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Journal Article
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Abstract
DC loads or sources like motor drives, batteries, and strings of photovoltaic (PV) panels with power levels up to the lower single-digit kilowatt range are typically connected to the single-phase mains using bidirectional ac-dc converters providing power factor correction (PFC) functionality. Often, a dc output voltage range spanning from values lower than to values greater than the grid voltage amplitude is required, and hence, the ac-dc converter must provide buck-boost capability. As an alternative to conventionally used two-stage systems, single-stage converters promise lower realization effort and, in particular, fewer active components like power transistors. This article, therefore, analyzes a new bidirectional single-stage single-phase ac-dc buck-boost converter with only three power transistors, whose topology is identified using a systematic approach that is briefly summarized. Advantageously, the new ac-dc converter's negative dc output terminal is connected to the mains neutral, i.e., there is no common-mode (CM) voltage at the dc output. The operating principle is explained in detail, and a new advanced modulation method is proposed, which reduces the switching losses by more than 33% and lowers the component stresses. A 3.3-kW proof-of-concept (non-optimized) demonstrator is developed, which connects to the single-phase European ac mains (230 V rms, line-to-neutral) and provides a wide dc output voltage range of 300-450 V. Both the conventional and the proposed advanced modulation method are experimentally verified, confirming an improvement of the peak efficiency from 95.9% to 96.7% (300 V dc output, 2.5 kW output power) for the advanced modulation method.
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published
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13 (3)
Pages / Article No.
3094 - 3106
Publisher
IEEE
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Subject
AC-DC converter; buck-boost; electric vehicle (EV) charger; low-switch-count converter topologies; photovoltaic (PV) inverter; single phase; topology synthesis; zero common mode (CM)
Organisational unit
02294 - Mechatronische Systeme / Mechatronic Systems
03573 - Kolar, Johann W. (emeritus) / Kolar, Johann W. (emeritus)