Design of an electronic ballast based on a resonant converter controlled by a variable capacitance strategy

The design of an electronic ballast based on a Class D voltage switching resonant inverter is presented. A new control strategy based on a variable capacitance diode used to regulate the resonant converter frequency is proposed. The control allows the lamp to start by increasing the frequency to the resonant point, producing the necessary high voltage, then varying the frequency value to a minimal current consumption operating point. The ballast includes a power factor corrector and the experimental results show energy savings of about 30% at a very competitive cost when compared to an electromagnetic ballast