Fluorescent lamps operate most efficiently if driven by AC (alternating current) power at a frequency of around 30 KHz (kilohertz). To operate efficiently from standard power distribution systems, an electronic ballast converts AC line power at 50 Hz (hertz) to 60 Hz to higher frequency AC power. The ballast must have a low power factor (PF) and produce little total harmonic distortion (THD) at the input AC line.
To accomplish these tasks, an electronic ballasts has a rectifier to convert AC power to DC power, a boost converter for increasing the voltage of the DC power above peak of the line as well as providing power factor correction, and an inverter for converting voltage; boosted DC power into AC power at around 30 KHz.
The boost converter consists of a boost inductor and a transistor operated as a switch. The output of the boost converter is connected to a half-bridge two transistors inverter. The output of the half-bridge inverter, through a transformer, drives the fluorescent lamps.
The usual topology of such a boost converter coupled to an inverter requires three power transistors. The result is a circuit with a large number of parts, and thus increased complexity and increased assembly costs.