Efficiency Analysis of Bridgeless Three-Level PFC Circuits Based on Modal Segment Integration Method

Traditional methods for evaluating power electronic converter efficiency heavily rely on simulations and often lack theoretical support, which can lead to inaccuracies and limit effective design optimization. To address these shortcomings, this paper proposes a modal segment integration method based on a device loss model. The analysis begins with the operating principles of the proposed circuit topology. A detailed power loss model is then established and applied to representative operating modes. Using the modal segment integration method, the total loss over a full operating cycle is calculated. Theoretical analysis estimates the system efficiency exceeds 98%. To validate the proposed method, a 1 kW experimental prototype with a 400 V DC output is built. The results show that the maximum error between the theoretical and experimental efficiency is less than 0.4%. This method offers a reliable theoretical basis for efficiency evaluation of three-level converter topologies and supports the structural design and performance optimization of power electronic systems.