Constant Switch Stress Control of Hybrid Switched Capacitor DC-DC Converters

Abstract

This work proposes the constant switch stress (CSS) control algorithm to achieve both active balance and output regulation for hybrid switched capacitor (SC) DC-DC converters. CSS control is a hysteresis-based solution that highlights simple implementation and fast transient response. Discontinuous conduction mode (DCM) is possible at light load to reduce the switching loss. Another unique operation mode (CSS mode) protects semiconductor devices from overstress at heavy load. For load levels in between, pseudo constant switching frequency can be maintained by dynamically adjusting the hysteresis window. The performance of CSS control is validated on a 5-level flying capacitor multilevel (FCML) converter prototype.