Research On Topology And Application Of Switched-controlled Capacitor SCC

The technology of switch-controlled capacitor(SCC)is to control the amount of charge in the capacitor for a period of time by controlling the turn-on and turn off of switch,then,the purpose of controlling the equivalent capacitance is achieved.SCC is widely used in the regulation and control of the LLC resonant converter with constant voltage source and the dimming of ballast or LED power supply.In this paper,the main research object of this paper is to study the application of the SCC in the resonant converter and the LED current sharing drive circuit:First,the topology research of SCC.Summarizes the existing SCC topology,and put forward two kinds of new SCC topology;a detailed analysis of the work cycle of various SCC topology is analyzed;and the application of SCC structure in the two-order and the third-order resonant converter is enumerated.Second,the research on the operating characteristics of the resonant converter with integrated SCC.Frequency conversion control is a common control method for resonant converters,but the wide range of operating frequency will reduce the performance of magnetic components and increase the design complexity.The output of the resonant converter can be controlled by changing the equivalent capacitance of the resonant circuit.The operating characteristics of SCC-LCL resonant converter based on PWM control and SCC-LCL-T resonant converter based on half bridge phase shifted control are analyzed in detail.The effectiveness and feasibility of the proposed SCC structure applied to the resonant converter topology are verified by simulation and experiment.Third,multi channel LED driver with integrated SCC.LED is a promising new generation of green lighting source,LED is usually used in series and parallel,but the LED is a negative temperature coefficient,which will aggravate the degree of uneven flow,and seriously reduce the reliability of LED.Therefore,the current sharing technology of LED module must be introduced.In this paper,a new kind of multi-channel LED driver circuit is proposed,which is based on the SCC and the charge-discharge balance.The working cycle of the drive circuit is analyzed in detail,and the SCC equivalent capacitance value is used to control the LED drive current.The prototype can be used to realize the accurate current sharing between four LED and LED modules in the module,and the module can be adjusted independently by SCC,which has good control performance and expansibility.