Abstract:
This research proposes an analysis and design of a DC-side symmetrical zerocurrent-
switching (ZCS) Class-D current-source driven resonant rectifier to improve a
low power-factor and a high line current harmonic distortion for the lighting
applications. The analysis of a junction capacitance effect of the Class-D ZCS rectifier
diode, which has a significant impact to the line current harmonic distortion, is
discussed in this paper. The design procedure is based on the principle of the
symmetrical Class-D ZCS rectifier, which also ensures more accurate results and
provided a more systematic and feasible analysis methodology. Improvement of the
power quality is achieved by using the output characteristics of the DC-side Class-D
ZCS rectifier, which is inserted between the front-end bridge-rectifier and the bulk-filter
capacitor. By using this symmetrical topology, the conduction angle of the bridgerectifier
diode current is increased and low line harmonic distortion and power-factor
near unity were naturally achieved, the peak and ripple values of the line current are
also reduced, allowing for a reduced filter-inductor volume of an electromagnetic
interference (EMI) filter. In additional, low-cost standard-recovery diodes can be
employed as bridge-rectifier. A prototype of the ballast, operating at a 220-Vrms, 50-Hz
line voltage, was utilized to drive a T8-36W fluorescent lamp. The validity of
theoretical analysis is confirmed by simulation and circuit experiment.