Abstract:
The thesis will focus on the power factor correction and harmonic reduction circuit for
an electronic ballast of fluorescent lamp. At first different power factor correction
techniques are investigated and compared. Among them the valley-fill (VF) passive
power factor correction method is used to improve the power factor and THD. The basic
VF circuit is studied in detail and it is modified with four different schemes and the
effects of different circuit components are analyzed. The VF circuit is used because of
its simplicity, high efficiency and less expensive. The modified VF circuit with better
performance is proposed in this thesis. It is combined with a current fed resonant
inverter as a power circuit, which provides isolation to the driver circuit without the use
of any isolation devices. When the inverter is cascaded with the valley fill circuit, the
input inductor inherits the boost inductor characteristics and allows the line current to
achieve close to sinusoidal shape. As a result the total harmonic distortion reduced.
Lastly the modified VF ballast with extended conduction angle is analyzed with three
different configurations to have a suitable design which will enhance the performance.
In this work, the best result is achieved where the power factor (PF) is 0.995, efficiency
is 98.79 % and the THD is 9.83 %. The ORCAD PSPICE simulation results for each
configuration are presented in the thesis to highlight the performance of the proposed
circuit.
