Achieving Soft-Charging and Over 20% Input Current Ripple Reduction in a 48-to-6 V Dickson Converter Using 3-Phase Split-Phase Control

Hybrid switched-capacitor (HSC) converters can outperform conventional switched-capacitor and switched-inductor converters by incorporating inductors within capacitor charging/discharging loops, thereby eliminating hard-charging losses. Among these, the Dickson HSC topology achieves the minimum possible switch VA stress, resulting in superior efficiency compared to other HSC topologies. While odd-conversion-ratio Dickson topologies can achieve complete soft-charging using two-phase operation, even-conversion-ratio topologies cannot. Previous work has introduced a 4-phase split-phase control scheme to enable soft-charging operation. However, the 4-phase scheme increases the input current RMS due to reduced conduction time of the input switch. This poses challenges in applications where line losses are significant, buffer capacitor volume is critical, or minimal input noise and electromagnetic interference (EMI) are required. This work presents a 3-phase split-phase control scheme that maintains input current conduction for a constant 50% of the switching period, regardless of the conversion ratio. The method is also extendable to any even-ratio Dickson topology. Hardware validation of the proposed scheme on a 48-to-6 V Dickson converter confirms significant reductions in input current ripple compared to prior techniques.