TW200617844A - DC/AC conversion fluorescent lamp driving circuit - Google Patents

Abstract

This invention provides a DC/AC converting fluorescent lamp driving circuit. It converts a DC power supply into an AC power supply using for drive a load. The DC/AC converting driving circuit comprises a full-bridge switch, a resonance trough circuit, and a driving circuit. The full-bridge switch electric connects with the DC power supply and switches to the DC power supply to output a pulse signal. The full-bridge switch contains a first power switch, a second power switch, a third power switch, and a fourth switch, the first power switch and the second power switch, the third power switch and the fourth power switch electrically and respectively are connected to form two straight arms. The resonance trough electric connects between the full-bridge switch and the load to boost and filter the pulse signal so as to convert into the AC power supply and supply power to the load. The driving circuit feeds an output of the load to provide four sets of pulse width modulation (PWM) signals for controlling turn-on and turn-off of the first power switch, the second power switch, the third power switch and the fourth switch. The four sets of PWM signals utilize the same frequency, two sets of turning-on duty cycles of the four sets of PWM signals are less than 50%. In addition, another two sets of turning-on duty cycles are greater than 50%. PWM signals utilize the same frequency, two sets of turning-on duty cycles of the four sets of PWM signals are less than 50%. In addition, another two sets of turning-on duty cycles are greater than 50%.