Load Observing System Based on Wave Reflection for Soft-Switching Control of MHz-Frequency Resonant Inverter Against Load Fluctuations | Zendy

Aoi Oyane | Zendy; Kazuhiro Umetani | Zendy; Eiji Hiraki | Zendy

Open Access

Load Observing System Based on Wave Reflection for Soft-Switching Control of MHz-Frequency Resonant Inverter Against Load Fluctuations

Author(s) -

Aoi Oyane,

Kazuhiro Umetani,

Eiji Hiraki

Publication year - 2025

Publication title -

ieee access

Language(s) - English

Resource type - Magazines

SCImago Journal Rank - 0.587

H-Index - 127

eISSN - 2169-3536

DOI - 10.1109/access.2025.3587595

Subject(s) - aerospace , bioengineering , communication, networking and broadcast technologies , components, circuits, devices and systems , computing and processing , engineered materials, dielectrics and plasmas , engineering profession , fields, waves and electromagnetics , general topics for engineers , geoscience , nuclear engineering , photonics and electrooptics , power, energy and industry applications , robotics and control systems , signal processing and analysis , transportation

Applying MHz-frequency inverters to radio frequency (RF) power sources for plasma applications has been challenging because capacitive loads caused by load fluctuations cause destructive hard-switching. This paper proposes a MHz-frequency load impedance estimation method for soft-switching control. The proposed system estimates the load impedance by utilizing a directional coupler that is typically built into an RF power source to observe traveling and reflected waves. Therefore, unlike typical low-frequency power electronics systems, the proposed system does not require output current sensors which are not suitable for MHz-frequencies. In the experiment, the proposed method was tested using the auxiliary switch-inductor circuit of a 3.75MHz gallium nitride (GaN) full-bridge inverter as the control target. Capacitive load detection by the proposed method was experimentally verified, and soft-switching control was realized under capacitive load. The transient response of the control under a fluctuating load that changes from inductive to capacitive was also measured. The inverter transitioned to soft-switching within 2.31μs after a load change, and hard-switching took only 8 cycles.

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