A Gain/Efficiency-Improved Serial-Parallel Switched-Capacitor Step-Up DC-DC Converter

A new scheme of a gain/efficiency-improved serial-parallel switched-capacitor converter (SPSCC) is proposed by combining an adaptive-conversion-ratio (ACR) and pulse-width-modulation (PWM) control for step-up DC-DC conversion. For improving gain, the power part consists of one m(c)-stage cell and one n(c)-stage cell in cascade to obtain the step-up gain of (m(c) + 1) x (n(c) + 1) at most. For improving efficiency, the ACR control with adapting stage number m, n is presented to select a proper gain of (m + 1) x (n + 1) (m = 1, 2, ..., m(c), n = 1, 2, ..., n(c)) according to the desired output. Further, the PWM control is adopted to enhance output regulation as well as robustness to source/loading variation. Some theoretical analysis and control design include: formulation, steady-state analysis, conversion ratio, efficiency, output ripple, stability, capacitance selection, and control design. Finally, the performance of this scheme is verified experimentally on a SPSCC prototype, and all results are illustrated to show the efficacy of this scheme.