High-power-factor light-emitting diode lamp power supply without electrolytic capacitors for high-pressure-sodium lamp retrofit applications

A long-life high-power-factor integrated converter able to supply light-emitting diode (LED) lamps in high-pressure-sodium lamp retrofitting applications is presented. The proposed converter is the integration of a buck-boost converter with a buck converter, thus providing the necessary high input power factor and voltage transformation ratio to supply the low-voltage LED array from the mains. The analysis of the converter is carried out, and a design procedure is proposed. The design is also performed so that low capacitances are needed at the output of each semi-stage. This allows for the use of long-life film capacitors, thus matching the converter lifetime to that of the LED lamp. A laboratory prototype supplied from 230 V_rms/50 Hz mains used to drive two LED arrays in series with a total output power of 100 W is presented.