Dimming Control of Electronic Ballast with High Power Factor for Lighting Applications
Due to the high costs of expanding generation and transmission capacities; utilities have been initiating programs to reduce peak power demand by the customer. A number of these programs, which are commonly referred to as demand side management programs, have turned to the promotion of electronic ballast as an alternative to traditional inductive ballast. A novel single-stage high power factor dimmable electronic ballast with very high power factor is presented in this paper. The proposed lamp power circuit combines the SEPIC converter and a half bridge resonant inverter to form a single-stage inverter to power the lamp. The resulting circuit provides a compact and cost-effective circuit configuration for electronic ballast designs. By operating the SEPIC power factor corrector in discontinuous conduction mode, the average line current is in phase with the line voltage and a very high power factor is achieved at the input. In the proposed design, zero current switching (ZCS) is achieved at the turn-on of the MOSFET switches to maintain high efficiency for the overall circuit. Dimming control is used to control the lamp power. The dimming feature can be achieved through different methods: frequency modulation, pulse width modulation changing the output filter parameters and by controlling the bus voltage. The duty cycle of the integrated switch is varied in order to control the bus voltage and, consequently, the power delivered to the lamp. Simulation results are provided for a different values of duty ratio.
Author Name: Nisha B. Kumar and B. Aswathy
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Keywords: Electronic Ballast, High Power Factor, Dimming Control