Electronic ballast and power controller

Abstract

A relatively high efficiency, relatively light weight, relatively small electronic ballast or AC power controller for use in aircraft and elsewhere for controlling a fluorescent lamp load or other load includes an EMI filter, a multi-purpose transformer, a power conversion stage and a control circuitry stage. The ballast or controller operates to increase or decrease the voltage of the incoming sine wave AC voltage through a charging path for an energy storage inductor choke cooperating with an energy storage capacitor wherein the charging path for the capacitor is different from the discharge path of the capacitor to isolate the load from the charging of the capacitor and thus to provide an output to the load which is independent of the charging path and which is out of phase with the incoming waveform. This is achieved through conversion of the incoming AC power to a higher frequency and to a higher or lower voltage, under the control of a switching system, and reconversion to the input frequency, followed by filtering to remove the high frequency components. The system includes various novel feedback loops for the lamp current and the like for control of lamp current and dimming control. Various forms are described including a high efficiency form in which the incoming power is added to the ballast output for operation of the lamp load.