BALLAST SELF OSCILLATING INVERTER WITH PHASE CONTROLLED VOLTAGE FEEDBACK

摘要

A self-oscillating ballast inverter circuit for powering a gas discharge lamp. The circuit is used in a ballast inverter to compensate positive resonance frequency shift in the inverter load during lamp starting. The circuit is built on low power components and incorporated in a DC to AC inverter, providing transient advance angle for inverter switching transistors (M1, M2). This angle advance is increased in proportion to incremental output inverter voltage that is above a selected threshold voltage. Therefore, the inverter operates above resonance frequency during lamp starting, avoiding transient cross conduction in transistors in the circuit. The feedback circuit limits voltage and current stresses that may destroy some ballast components over time. The circuit also generates a signal for a protection circuit that is activated if the lamp fails to start.