A Wide-Regulation-Range Hybrid Switched-Capacitor Converter for 48V Automotive Power Systems

TL;DR

This paper introduces a novel hybrid switched-capacitor converter with multi-mode modulation for efficient wide-range voltage regulation in 48V automotive systems, validated by hardware experiments.

Contribution

The paper proposes a new multi-mode modulation scheme enabling wide regulation range and high efficiency in hybrid switched-capacitor converters for automotive applications.

Findings

Achieved ZCS operation over 0.2--0.4 voltage ratios with over 92% efficiency at 100W.

Demonstrated both ZCS and ZVS operation experimentally.

Extended the practical regulation range of resonant switched-capacitor converters.

Abstract

This paper presents a hybrid switched-capacitor converter (HSCC) with a novel multi-mode modulation (3M) scheme for wide-range voltage regulation in 48-V automotive power systems. By introducing a three-state operating sequence beyond the conventional 2:1 resonant operation, the proposed converter achieves variable step-down conversion ratios while preserving soft-switching operation in most transitions. The proposed modulation supports both zero-current switching (ZCS) and zero-voltage switching (ZVS) modes, enabling efficient operation over a broad range of load and conversion conditions. To enable voltage regulation, a closed-loop control configuration is proposed with a linear proportional-integral (PI) controller, with gain tuning assisted by reinforcement learning (RL) to address the converter's nonlinear and variable-frequency nature while maintaining good transient performance. A hardware prototype was built to validate the proposed modulation scheme. The measured results verify ZCS operation over voltage conversion ratios of 0.2--0.4, with a peak efficiency exceeding 92\% at 100~W, and efficiency above 88\% over a wide operating range for 3:1 conversion. The feasibility of both ZCS and ZVS operation is also experimentally demonstrated. These results show that the proposed HSCC significantly extends the practical regulation range of resonant switched-capacitor converters while maintaining high efficiency.