Abstract—This paper proposes twomethods of reducing the storage
capacitance in the ac/dc power supplies for light emitting diode
(LED) lighting. In doing so, film capacitors can be adopted instead
of electrolytic capacitors to achieve a long power supplies’ lifetime.
The voltage ripple of the storage capacitor is intentionally
increased to reduce the storage capacitance. The method of determining
the storage capacitance for ensuring that the boost power
factor correction converter operates normally in the whole input
voltage range is also discussed. For the purpose of further reducing
the storage capacitance, a method of injecting the third harmonic
current into the input current flow is proposed. While ensuring
that the input power factor is always higher than 0.9 to comply
with regulation standards such as ENERGY STAR, the storage
capacitance can be reduced to 65.6% of that with an input power
factor of 1. A 60-W experimental prototype is built to verify the
proposed methods.
Index Terms—Harmonic current injection, LED, power factor
correction (PFC), power supply, voltage ripple.