Analysis and design of a dimmable electronic ballast controlled by a switch-controlled capacitor

This paper presents the related principle and analysis of the dimmable electronic ballast controlled by the switch-controlled capacitor (SCC). A Fourier-series expansion is used to derive the operational principle of the zero-voltage-switching Class-D series-parallel-load-resonant dimmable electronic ballast regulated by the SCC. By the adaptation of the SCC, the lightness of the system can be adjusted, while the operation frequency of the Class-D converter can be kept constant. The dimmable effect controlled by the variable SCC is examined. The analytical results are verified by simulations and experiments. Furthermore, the design considerations for the dimmable electronic ballast with SCC control are also presented in this paper.