Anti-flicker digital PFC controller for HID lamp electronic ballast

HID lamps are sensitive to voltage supply fluctuations producing an effect on human visual perception, known as flicker. The fluctuations are typically caused by the repetitive variation in the power consumed by loads, or by the connection and disconnection of significant loads. New improvements are presented in the power factor correction (PFC) stage for electronic ballasts of high intensity discharge (HID) lamps. A universal low frequency voltage fluctuation detection algorithm is proposed, consistent with the maximum human light flickering perception. A correct actuation on the output voltage loop of a current sensorless digital control for the PFC stage reduces the lamp sensitivity to utility fluctuations. Simulation and experimental results show how lamp flicker is avoided and power factor correction is achieved without measuring the input current.