Phase-controlled quadruple LCp resonant inverter to drive 600W HPS lamps

This paper presents the analysis and design of a new configuration of a resonant inverter suitable for high-intensity discharge (HID) lamp ballast applications. The proposed inverter results from the parallel connection of four class D LC_p resonant inverters, sharing the total load current. In this way, the conduction losses are reduced and high frequency operation is achieved for high power lamps. The power control is implemented at constant frequency, modifying the phase displacement among the output voltage of each inverter section. Considering that the deviation of the operation point caused by the control action deteriorates the converter efficiency, this design guarantees minimum control action to correct the lamp power deviation caused by the lamp aging. A 600W prototype has been built to validate the design proposal.