Designing a dimmable electronic ballast with voltage control for fluorescent lamp

This paper provides a design guideline for the high-frequency dimmable electronic ballast with voltage control for fluorescent lamps. The dimming feature is accomplished by controlling the DC-link voltage of the inverter stage of the electronic ballast. Based on the power-dependent lamp model, the control equations are derived by fundamental approximation, and then the dimming characteristics of the fluorescent lamp can be calculated. Satisfied performances are achieved by properly choosing the circuit parameters under the considerations of the filament heating, the starting voltage, switching losses, circuit component stresses and the applicable DC-link voltage range. An electronic ballast with the half-bridge series-resonant parallel-load inverter for the rapid-start fluorescent lamp is used as an example for illustrating the design procedure. A laboratory circuit was built and tested. The experimental results agree well with the analytical values