Naturally clamped snubberless soft-switching bidirectional current-fed three-phase push-pull DC/DC converter for DC micro-grid application

A bidirectional current-fed three-phase push-pull dc/dc converter is proposed for DC micro-grid application. The proposed converter is analyzed and designed to interface two dc buses of 48 V and 380 V in a microgrid. An innovative novel modulation technique is proposed to clamp the device voltage spike across primary side current-fed devices at turn-off solving traditional problem. The proposed modulation helps achieve natural zero current commutation of low voltage side (LVS) devices and zero voltage switching (ZVS) turn-on of high voltage side (HVS) devices. This eliminates the use of passive/active snubbers in conventional current-fed topologies to mitigate the voltage-spike across the devices. The steady-state operation, analysis, and design of the converter with proposed modulation are explained. Soft-switching conditions are derived. Simulation results obtained using PSIM 9.3 have been illustrated to verify the operation, analysis and design. Experimental results for full load (1kW) and partial load (500W) as a proof-of-concept are demonstrated to validate the claims and show the converter performance.