Search

An analysis and design of a single-stage electronic ballast with a dc-side Class-DE low-dv/dt resonant rectifier is studied in this paper to improve a poor power-factor and low line harmonic. The power-factor correction is achieved by utilize an output characteristics of a Class-DE rectifier, which is inserted between the front-end bridge rectifier and the bulk-filter capacitor. The design procedure is based on the principle of the Class-DE rectifier, which also ensures more accurate results and the proposed scheme provided a more systematic and feasible analysis methodology. The active switches can be operated under the soft-switching condition. By employing an electromagnetic interference filter after bridge rectifier, the standard-recovery diode for bridge rectifier can be employed, the cost can be reduced, the conduction angle of the bridge-rectifier diode current was increased, and low line harmonic distortion and a power factor near unity were achieved. The dc-side Class-DE rectifier is driven by a high-frequency current source, which is obtained from the square-wave output voltage of the Class-D series-parallel resonant inverter through an LC-series circuit. A prototype of the ballast, operating at an 84-kHz fixed frequency and a 220-V rms, 50-Hz line voltage, was utilized to drive a T8-36 W fluorescent lamp. The validity of this approach was confirmed by simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents the use of a novel, single-stage high-power-factor electronic ballast with a symmetrical class-DE low-dv/dt resonant rectifier as a power-factor corrector for fluorescent lamps. The power-factor correction is achieved by using a bridge rectifier to utilize the function of a symmetrical class-DE resonant rectifier. By employing this topology, the peak and ripple values of the input current are reduced, allowing for a reduced filter inductor volume of the EMI filter. Since the conduction angle of the bridge rectifier diode current was increased, a low-line current harmonic and a power factor near unity can be obtained. A prototype ballast, operating at an 84-kHz fixed frequency and a 220-Vrms, 50-Hz line input voltage, was utilized to drive a T8-36W fluorescent lamp. Experimental results are presented which verify the theoretical analysis. [ABSTRACT FROM AUTHOR]