Prediction and Mitigation of Common Mode Noise in a Four-Switch Buck-Boost Converter

The Four-Switch Buck-Boost (FSBB) converter can function as a buck, boost, or buck-boost converter and employ various modulation schemes to reduce the electrical stresses of active and passive components and enhance efficiency. However, switching power devices in the FSBB converter generate electromagnetic interference (EMI), influenced by factors such as modulation techniques and the physical layout of the converter. There is a need to address EMI - related aspects during the design phase to ensure compliance with standards and avoid costly design changes and repetitive EMI tests. This paper proposes an equivalent circuit-based analytical model to predict conducted emissions from an FSBB converter. The simplified model aids the first-pass EMI filter design process. A hardware prototype of the FSBB converter is constructed. EMI measurements are presented from pre-compliance tests conducted at the laboratory to validate the effectiveness of proposed modelling and filter design approaches.