A Pulse Igniting Circuit for Electronic Ballast With the ZVS-QSW Converter

In the paper, a novel pulse ignition circuit is proposed for electronic ballast with the zero-voltage-switching quasi-square wave (ZVS-QSW) converter; the voltage pulse of the proposed igniting circuit contains both a high frequency part and a low frequency part; the high frequency part made it easy to exit the gas in the ionization conduction state in the high-intensity discharge lamp, and the low frequency part makes it easy to lower the igniting potential and provides the continuous pulse energy. The circuit is with few components, low costs, high reliability, and easy to control. The circuit model is analyzed in detail and the influence of the circuit parameters on the pulse amplitude and width is given in this paper. The peak current is limited and the amplitude variation caused by the deviation of the parasitic capacitor for the transformer is restricted by the auxiliary inductor. The auxiliary inductor and the transformer parasitic capacitor form another resonant circuit. As a result, an igniting pulse sequence with two different frequencies is applied to the lamp and both pulse amplitude and width are guaranteed. In the laboratory, the circuit is used in a 70-W metal halide lamp electronic ballast with the ZVS-QSW converter, and the lamp can be ignited reliably.