Electronic ballast for 250 W HPS lamps based on the LCC resonant inverter with soft start-up and quasi-optimum control

This paper presents the design and control of an electronic ballast based on the full-bridge series parallel (LCC) resonant inverter topology suitable for driving high-power high-intensity discharge lamps. By using the properties derived from the transfer functions of the LCC inverter, a soft start-up method is proposed. The lamp ignition is achieved keeping the voltage and current variables without exceeding pre-fixed peak values, with addition of no extra component to the power stage for this purpose. In steady state operation, the proposed control method minimizes the reactive volt-amperes in the resonant tank. The experimental results are given for high-pressure sodium lamps of the type Sylvania SHP250W