A new multiresonant three-phase utility frequency ac (UFAC) to high-frequency ac (HFAC) direct power converter for the industrial metal hardening induction heating (IH) applications is presented in this article. The proposed ac–ac converter features direct frequency conversion with the wide range of soft switching by means of the minimized numbers of bidirectional switches. The conducting current of bidirectional switches can be reduced effectively owing to the multiresonant tank while keeping a high power in the IH load. Accordingly, the practical power converter with simplicity, cost-effectiveness, and high efficiency can be realized on the basis of a simple pulse-frequency modulation (PFM). The circuit topology and operating principle of the proposed converter are described, after which the design procedure of the multiresonant tank and switching frequency is presented. The performances on the soft switching and the steady-state PFM characteristics of the ac–ac converter are evaluated in experiment with the 1.7 kW/85–90-kHz prototype. Finally, the feasibility of the proposed ac–ac converter is evaluated from a practical view point.

中文翻译：

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适用于金属硬化高频感应加热应用的三相至单相多谐振直接交流转换器


本文介绍了一种用于工业金属硬化感应加热 (IH) 应用的新型多谐振三相工频交流 (UFAC) 至高频交流 (HFAC) 直接功率转换器。所提出的交流-交流转换器的特点是通过最少数量的双向开关实现直接频率转换和广泛的软开关。多谐振回路可以有效降低双向开关的导通电流，同时保持IH负载的高功率。因此，可以基于简单的脉冲频率调制(PFM)来实现具有简单性、成本效益和高效率的实用功率变换器。描述了所提出的转换器的电路拓扑和工作原理，然后介绍了多谐振回路和开关频率的设计过程。通过 1.7 kW/85-90-kHz 原型机的实验评估了 ac-ac 转换器的软开关性能和稳态 PFM 特性。最后，从实际角度评估了所提出的交流-交流转换器的可行性。