Protection circuit for electronic ballasts which use charge pump power factor correction

A circuit for powering a gas discharge lamp from a source of AC power comprising:

• a first rectifier having a first rectifier input and a first rectifier output, the first rectifier input coupled to the source of AC power;
• a smoothing capacitor coupled in parallel with the first rectifier output;
• a diode with a shunt resistor;
• a second rectifier having a second rectifier input and a second rectifier output;
• the second rectifier input coupled to a high frequency inverter;
• a switch across the second rectifier output;
• a storage capacitor in parallel with an inverter for driving a gas discharge lamp;
• a sensor for sensing conditions when the voltage on the energy storage capacitor is excessively high;
• the smoothing capacitor, the diode with shunt resistor,
• the energy storage capacitor and the second rectifier output connected in series.

A method of a powering a gas discharge lamp from a source of AC power at a first frequency comprising the steps of:

• rectifying the AC power into a first DC power;
• inverting the first DC power into AC power at a second higher frequency;
• rectifiying some of the AC power at a second high frequency into a second DC power;
• storing some of the first DC power and second DC power in an energy storage capacitor;
• energizing the gas discharge lamp with the AC power at the second frequency;
• sensing when the voltage on the energy storage capacitor is excessively high
• disabling the rectifying of some of the AC power at a second higher frequency into a second DC power if the voltage on the energy storage capacitor is excessively high.