Advanced Modeling Technique of Class-E Inverter Considering Low R_on of eGaN FETs and Different Design Procedures

Class-E inverters have been used extensively in high-frequency applications with eGaN (enhancement-mode Gallium Nitride) devices due to their high switching speed and low on-state resistance (in the order of a few mΩ). However, the developed generalized averaging model to control the class-E inverter in prior literature works only for a class-E inverter with a high-Q resonant output network and high on-state resistance (R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</inf> ≥ 0.5Ω) switches due to the presence of R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</inf> in the denominator in their state equations. Therefore, this paper first eliminates R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</inf> from the denominator of the state equations by incorporating u(t) appropriately in the state equations, where u(t) is the complementary function of the gate drive signal. Subsequently, leveraging the developed state equations, we propose a model suitable for a class-E inverter with a high-Q resonant output network. Lastly, due to the high distortion of the output current and the voltage across the eGaN FET, we develop another model for the class-E inverter with a DC-blocking output capacitor by adding more harmonic components in state variables without increasing complexity. Our simulation results from PLECS and experimental results with the 5MHz eGaN FET-based class-E inverter are provided to validate the efficacy of the proposed models.