Impact of Nonlinear Parasitic Capacitance on Class-DE Inverters: Analysis and Research Methodologies

Class-DE inverters with low voltage stress are highly efficient and compact. High-frequency resonance is commonly used for soft switching. However, at high frequencies, MOSFET nonlinear parasitic capacitance can disrupt soft-switching and reduce energy conversion efficiency. This study analyzes the effects of MOSFET parasitic capacitance on class-DE inverter parameters through simulations and analytical analysis. Two key findings emerge: Firstly, achieving soft switching in class-DE inverters depends on load variations and requires adjusting the duty cycle (D). Secondly, the output voltage amplitude is proportional to the input voltage for a given duty cycle, indicating the dominant influence of MOSFET parasitic capacitance on soft-switching performance and energy conversion efficiency. This analysis contemplates a design methodology that accounts for nonlinear capacitance to identify the optimal duty cycle and resonance parameters within a class-DE inverter. Experimental validation confirms the impact of nonlinear capacitance, demonstrating the feasibility and effectiveness of the proposed approach.