High frequency ballast for gaseous discharge lamps

摘要

An electronic frequency inverter circuit receives input electrical power at a lower frequency and energizes in a range of higher frequencies a load circuit (36)(37) including gaseous discharge lamps which varies with frequency. First and second switches (30)(31) are operated alternately by a logic circuit mode control (40) such that the switches operate at the high frequency range and the frequency of current in the load circuit varies as the magnitude of said source voltage (10) varies. The load circuit has an impedance such that the peak amplitude of the load current remains substantially constant despite variations in the magnitude of said source voltage to achieve a desirable crest factor for the load current. A high current limit circuit rapidly turns off the switches when excessively high current begins to flow through the switches. Low voltage is supplied in port from the high frequency current. Normal operation is ensured during start-up, for reduced line voltage and for a semiconductor chip embodiment.