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A single-stage high-power-factor electronic ballast with a Class-DE low-dv/dt rectifier as a power-factor corrector is proposed in this paper. The power-factor corrector is achieved by using a bridge rectifier that acts as the Class-DE low-dv/dt rectifier. The Class-DE low-dv/dt rectifier is driven by a high-frequency current source, which is obtained from the square-wave output voltage of the Class-D parallel resonant inverter through an LC -series circuit. By using this topology, the conduction angle of the bridge rectifier diode current is increased, and a low line-current harmonic is obtained. A prototype ballast is implemented to drive a 36-W fluorescent lamp. The switching frequency is fixed at about 84 kHz. Experimental results verify the theoretical analysis. The designed electronic ballast has a power factor of 0.99, a total harmonic distortion of 1.3%, a lamp current crest factor of 1.42, and 90% efficiency at full power.
Date of Publication: Oct. 2010