New soft-switching phase-shifted PWM high-frequency inverter-linked cycloconverter incorporating voltage-clamped quasi-resonant technique

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Abstract
A sinewave CVCF power conversion conditioning system (PCS) based on a high-frequency (HF)-isolated AC-link cycloconversion circuit using soft-switching phase-shifted PWM (PSM) and instantaneous voltage regulation schemes is presented. This advanced circuit topology of voltage-clamped quasi-resonant (QR) switch concept, which comprises two-cascaded power conversion stages operating under the principle of zero-voltage switching (ZVS), is introduced in order to minimize switching losses, device stresses, and EMI noise, and to remove a complicated HFAC snubber. A considerable improvement in power-density output performance and power conversion efficiency is achieved employing HF-link soft-switched cycloinversion concept. Its working principle is described, including the control processing strategy. A voltage-clamped QR sinewave PSM HFAC-inverter is analyzed under load-dependent current-source model and its approximate circuit design approach is discussed theoretically. The computer-aided simulation and experimental results are illustrated and evaluated for uninterruptible power supply (UPS) and utility line-interfaced power supply systems.