A Bridgeless BHB ZVS-PWM AC–AC Converter for High-Frequency Induction Heating Applications

Abstract

A new prototype of a zero voltage soft-switching (ZVS) utility frequency ac (UFAC) to high-frequency ac (HFAC) resonant power converter for induction heating (IH) applications is presented in this paper. The series resonant ac-ac converter proposed herein can process the frequency conversion without any diode bridge rectifier (DBR), thereby reducing the relevant conduction power losses. In addition, power factor correction (PFC) can be naturally achieved by the inductor-based boost halfbridge (BHB) circuit with the non-smoothed dc (NSDC)-link. The operation principle together with a IH load power regulation scheme is described, and the converter performances including ZVS operations and PFC are demonstrated in an experiment with a 3.0 kW-30 kHz prototype by comparing with the previouslydeveloped converter. Finally, the feasibility of the proposed ac-ac converter is evaluated from a practical point of view.Keywords-Utility-frequency (UF)-high frequency (HF) ac-ac power converter, diode full-bridge rectifier-less (bridgeless), boost half-bridge (BHB), non-smoothed dc (NSDC)-link, power factor correction (PFC), zero voltage soft-switching (ZVS), pulse-widthmodulation (PWM), induction heating (IH).

Single‐Stage ZVS‐PWM AC‐AC Power Converter Using All SiC Power Module for High‐Frequency Induction Heating Applications

“…9(a) to (c). Here, output control is implemented by asymmetric PWM applied to open loop to select active switches that control on-time ratio D depending on the polarity of v in at fixed operating frequency [4,6]. It should be noted that maximum output and maximum voltage (effective value) are obtained with respect to D, which means that both prototypes are designed at same conditions, and proper comparison is possible.…”

“…Now, "Q 1 turn-on loss" in Fig. 11(b) pertains to loss caused by residual voltage of the lossless snubber capacitor in on-duty control at the reduced output; however, this loss is a relatively small part of total loss [4,6].…”

“…Here, Q 1 and Q 2 are provided with lossless snubber capacitors C s1 , C s2 to enhance partial resonant ZVS, especially under heavy load, irrespective of output parasitic capacitance, as will be explained later. Now, the operating principle of the proposed ac-ac converter was explained in detail in previous reports [4][5][6], thus being omitted in the paper.…”

“…A number of schemes of power conversion from single-phase utility-frequency ac (UFAC) to highfrequency ac for home and professional induction heating (IH) appliances were proposed so far [2,3]; particularly, we proposed a bridgeless single-stage zero voltage soft-switching (ZVS) pulse-width modulation (PWM) controlled ac-ac converter (below referred to as merely "proposed ac-ac converter") as shown in Fig. 1 [4][5][6]. Experimental verification using prototypes confirmed high efficiency and improvement in power factor (PFC) due to the single-stage conversion using trench-gate high-speed reverse-conduction Si-IGBT module (Si-IGBT/Si-PN diode) as an active switch; however, switch conduction loss caused by higher voltage and switching loss caused by tail current specific to minority-carrier power devices were a problem.…”

Resonant Power Converters: An Overview with Multiple Elements in the Resonant Tank Network

“…Usually the operation is conducted at a frequency above the resonant frequency to achieve ZVS condition. Improvements in this field by the adoption of RPCs are presented in [51]- [53].…”