Pulsewidth modulation control of electronic ballast for dimming control of fluorescent lamps

The design of a resonant-inverter for the control of high efficiency lamps is presented. The topology of the circuit is a full-bridge parallel resonant-converter that switches at fixed frequency, and incorporates a pulsewidth modulation (PWM) method to control the output power. Expressions are provided that are fundamental for the design and the understanding of the operational principle. With a proposed lamp model and using it as the load of the inverter, the circuit operation is analysed. The experimental results of the design are compared with calculations and HSPICE simulations.