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)×(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)×(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.