Symmetric Dual-Buck Front-End Current-Source Converter with Low Common-Mode EMI

Common-mode (CM) electromagnetic interference (EMI) is one of the most vexing issues with pulse-width modulated (PWM) power converters and is further exacerbated by adoption of wide bandgap (WBG) devices. To tackle the challenge, this paper proposes a dual-buck DC-DC converter with symmetric circuit topology and gate signal implementation. Such topology is fed to a series-connected current source inverter (CSI) to form a buck-boost type current-source converter (CSC) system. The unique circuit topology and gate signal arrangement make the proposed CSC achieve inherent CM voltage cancellation and consequently leads to significantly lower CM EMI than conventional CSC, while maintaining CSC’s benefits such as reduced output dv/dt and higher fault-tolerance. An experimental setup has been built to comparatively evaluate the proposed converter, with results showing more than 20 dB (100 times) CM EMI reduction than conventional converters from 150 kHz to 2 MHz.