Regenerative signal amplifying gate driver of self-excited electronic ballast for high pressure sodium (HPS) lamp

A regenerative signal amplifying gate driver of a self-excited electronic ballast is presented. It can be used for a high pressure sodium (HPS) lamp without an auxiliary external ignitor. Since the HPS lamp requires very high ignition voltage at start up, the resonant frequency of the circuit must be increased to obtain high voltage oscillations in spite of relatively small resonant current. The presented gate driver amplifies the current of the gate drive transformer and raises the gate-source voltage quickly to turn on the MOSFET switches. Hence, the resonant frequency can be increased more than 100 kHz for large size switching devices. Besides, to protect the ballast from being destroyed, overvoltage/current protection and trigger delay circuits are designed. The HPS lamp used in the simulation and experiment has the rating of 400 W input power at 220 V input AC voltage source. The experiments show that the resonant frequency is above 150 kHz at start up and the inverter stops its operation by the overvoltage/current protection at nearly 3000 V.