Development of a Light Emitting Diode Lighting System with Power Factor Correction for Domestic Applications

摘要

The incandescent and fluorescent lighting systems which have been the most prominent electrical lighting choice for over 150 years are gradually being replaced in most homes with Light Emitting Diode (LED) Lighting Systems. This is due to their relatively low power consumption and good luminous intensity. LED lighting systems have revolutionized energy – efficient lighting. The significant feature of LEDs is that the light is directional with very low lagging power factor (0.2 – 0.6) as opposed to incandescent bulbs which spread the light more spherically with high power factor almost approaching unity. New LED designs address the directional limitation by using diffuser lenses and reflectors to disperse the light more. Since LED lighting represents a green technology, the issue of high power factor becomes very important. Power factor, defined as the ratio of real power consumed by a load (expressed in Watts) to apparent power (expressed in Volt-amperes), is a figure that ranges from zero to unity, it indicates the degree of distortion and phase shift in the current waveform. The work reported here proposes LED lighting system equipped with power factor correction driving circuit fed with dc – dc converter circuit. The power factor correction function is achieved by using switching converters circuit that operate directly from a full-wave rectified DC bus on a passive valley fill (PVF) circuit operating in Discontinuous Inductor Current Mode (DICM) for Power Factor Correction (PFC). This converter is simple to control, easy to construct and attractive for low cost application for domestic lighting. The results obtained have shown a LED lighting system with a lagging power factor of 0.85 that is energy – efficient compared to its conventional counterpart in domestic lighting applications.