Design of electronic ballast based on self-coupled transformer for low power high pressure sodium lamp

This paper researches the electronic ballast based on self-coupled transformer for 70W high pressure sodium lamp. The original power source comes from the grid, a boost pre-regulator between the input rectifier bridge and the filter capacitor serves unity power factor purpose. A buck topology with the LCpCs resonant circuit, which consists of self-coupled transformer and capacitors, satisfies the high voltage requirement during ignition and the normal operation of the high pressure sodium lamp. This paper analyses the circuit designs and their operation principles in detail. The proposed electronic ballast has small volume and light weight; hence it can be packed in lamp holder directly.