High frequency ballast for gaseous discharge lamps

摘要

An electronic circuit for receiving input electrical power at a lower frequency and for energizing a load at a higher frequency. The electronic circuit has a rectifier for rectifying the input electrical power received on an input thereof and a pre-regulator for changing the rectified AC voltage provided by the rectifier to a source voltage. The electronic circuit further has a non-resonant inverter for providing electrical power at the high frequency to the load and includes first and second switches and is connected to the pre-regulator and to the load circuit. A logic circuit is responsive to a sensed signal representing only current flowing in the first and second switches for operating the first and second switches. The frequency of current in the load circuit varies for any substantial change in the magnitude of the source voltage, for any change in load impedance, and for any change in a set point value. A device for setting the set point value is connected to the logic circuit. Finally, a reactance circuit is provided and connected in circuit with the load. The peak amplitude of current in the load has a peak value determined by the set point value. The device for setting the set point value can be a replaceable element having a predetermined relationship to the type of load connected to the electronic circuit or to the desired light output level. Also, the device for setting the set point value can be a variable element for selecting the set point value from a range of set point values and thereby changing the peak amplitude of current in the load. The variable element can also be controlled by a signal originating remotely from the logic circuit in the ballast.