Modular Snubberless Bidirectional Soft Switching 

This letter presents a modular naturally clamped snubberless bidirectional soft-switching current-fed dual 6-pack (CFD6P) dc/dc converter to interface two dc buses of large voltage difference such as 24 V and 380 V. It is therefore suitable for energy storage, uninterruptible power system, renewable energy system, vehicle, and micro-grid applications. The proposed novel secondary modulation technique forces the currents through the primary-side (low-voltage side) devices to reverse its direction resulting in zero-current switching (ZCS) or natural commutation of current-fed low-voltage side devices. Secondary-side (high-voltage side) devices are turned-on with zero-voltage switching (ZVS).

In addition, the resonance between the device parasitic capacitance and transformer leakage inductance achieves ZVS turn-on of the primary-side devices. Thus, the converter maintains a zero-voltage zero-current switching of the current-fed devices and ZVS of high-voltage devices. High-current applications needs short-circuit protection and that is built-in the converter inherently. It limits the peak current and circulating current through the devices resulting in low kVA rating devices. Steady-state operation, analysis, and design of the proposed converter have been studied and explained. Experimental results for 1-kW laboratory prototype have been demonstrated as a proof of concept to validate the claims.