Resonant Switched-capacitor Converters With High Power Density And Full-range Regulation

Resonant switched-capacitor conveters(RSCCs)are known to have the advantages of light weight,low cost,high power density,potential for integration,soft-switching and high efficiency.Thus,RSCCs are promising to be compact converters.However,prior studies show the narrow line regulation range of RSCCs dictated by circuit configurations,as well as the parasitic ringing problem.As a result,RSCCs suffer from extremely wide switching frequency band for voltage regulation,alone with significant switching loss,low utilization of inductor,turn-off overvoltage,and electromagnetic noise.Here,a comprehensive study of RSCCs is conducted in the aspects of circuit configurations and control methods.This thesis is organized as follows.Firstly,2X dual resonant switched-capacitor converters(DRSCs)with integrated passive regenerative snubber(PRS)are proposed to improve the light-load regulation capability and eliminate the parasitic ringing.In order to achieve full-range regulation with switching frequency varied below 2 times of resonant frequency for light loads,the new DRSCs are derived from (?)uk DRSCs by relocating the resonant inductors with rearranged operation principle.Furthermore,the integrated passive regenerative snubber,consisting of clamping capacitors and auxiliary diodes,features the eliminated parasitic ringing,declined turn-off overvoltage and reduced switching loss.A propotype was built to validate the full-range regulation capability and eliminated parasitic ringing of proposed converter under light load and heavy load conditions.Secondly,step-up series-parallel dual resonant switched-capacitor converters(SP-DRSCs)are proposed to extend the conversion ratio of 2X step-up DRSC.The step-up voltage conversion for SP-DRSCs is obtained by merging the 2X step-up DRSC with multiple series-parallel switched-capacitor cells.Then,the conversion ratio can be further extened by cascading techniques.In addition,the maximum capacity of SP-DRSCs is calculated to obtain the boundary of stable regulation region.Thus,the close-loop stability is discussed in terms of the circuit configurations and parameters.A propotype was built to validate the high step-up voltage gain and full-range regulation of proposed converter under light load and heavy load conditions.Then,the power density of step-up DRSCs is analyzed.On this basis,a guideline to improve the power density of step-up DRSCs is presented.The capacitance of resonant capacitors is calculated according to the voltage ripple and the operation principle of step-up DRSCs,while the maximum energy stored in capacitors and inductors can be determined.Then,the theoretical volume is obtained according to the stored energy and energy density of passive components,which provides the quantified power density of DRSCs.In addition,the volume of 2X step-up DRSC and step-up SP-DRSC is evaluated as examples.Consequently,the effect of SP cell counts to the inductor stored energy is discussed.Then,the design method is proposed to select the SP cell counts to improve the power density of step-up DRSCs.A propotype was built to validate the effectiveness of proposed method.Finally,inspired by the regulation principle of DRSCs,a practical full-range regulation(FR)method is proposed for RSCCs.As the operation principle of RSCCs is demonstrated by operation states in spatial dimension and by operation waveforms in time dimension,an analytical method is presented by decomposing the converter into capacitor charge and discharge sub-circuits,which can be rearranged similar to Buck converter.Thus,the FR method is proposed with full-range adjustment of duty cycle in sub-circuits under light load and heavy load conditions.A 3X step-up Ladder RSCC was built to validate the effectiveness of FR method.