Reduction of voltage stress in charge pump electronic ballast

The charge pump electronic ballast circuit, which employs a charging capacitor and a high frequency AC source to implement the power factor correction (PFC), has become an attractive topology for ballasting the fluorescent lamps because it eliminates the use of a bulky boost inductor. But this circuit has the problem of high voltage stress at light load operations especially during the preheat and startup operations of the lamps. Based on the analysis of the operation principle, the following solution was proposed. With the introduction of a second resonance stage, the voltage stress in this ballast was reduced by half. The experimental results are provided for verification.