Double Fourier Series-Based Sideband Harmonic Analysis of a Full-Bridge Converter

To respond to carbon-neutrality policies, interest in transportation powered by eco-friendly energy has increased. These systems require high-efficiency power conversion stages that enable bidirectional operation for driving and regenerative braking, where full-bridge converter topologies are widely adopted. However, harmonics in full-bridge converters can degrade efficiency and power density and cause electromagnetic compatibility issues. Therefore, the harmonic frequency bands and amplitudes must be accurately predicted. A single-variable Fourier series can estimate the baseband and carrier harmonics. However, the fundamental frequency of motor drive systems and railway vehicles generates the sideband harmonic which is determined by the baseband and carrier harmonics. Therefore, accurately predicting the sideband harmonics is difficult when using a single-variable Fourier series. This paper proposes a double Fourier series (DFS)-based sideband harmonic analysis of a full-bridge converter. To validate the applicability of the proposed method to various full-bridge based systems, four sets of results are compared over multiple combinations of the fundamental and carrier frequencies, including DFS without deadtime, DFS with deadtime, simulation results, and experimental results.