Performance comparison of electronic ballast topologies for low power compact fluorescent lamp application

The ballast provides a sufficient high voltage to ignite the lamp and then a proper lamp voltage to sustain the discharge under steady state operation. All the gas discharge lamps have negative incremental impedance thus they require a ballast to run it properly. The magnetic ballast are compact, reliable and operate at power frequency of 50 or 60 Hz, but they have few demerits like flicker, audible noise, high power loss, bulky in size and heavy in weight. As compared to magnetic ballasts, high frequency (20-100KHz) electronic ballasts offer more efficient, smaller, lighter and quieter operation. The electronic ballast comprises of a diode bride rectifier (DBR) and high frequency inverter circuit. The resonant circuit enables a high ignition voltage to be generated and makes the lamp current essentially sinusoidal. This simple scheme is still widely used because of its lower cost. However, it has very low power factor (PF) and large total harmonic distortion (THD) of ac main current. The low Power Factor increases the harmonic current and large THD pollutes the ac mains. In order to solve this problem, active PFC such as interleaved-boost PFC is used to improve the efficiency and power factor. Electronic ballast with the half bridge series resonant parallel loaded inverter is the most popular choice in many commercial products due to its simple configuration. The interleaved-boost power factor corrector (PFC) improves the input power factor and half bridge resonant inverter feeds the high frequency current to the compact fluorescent lamp.