subject: Electronic ballast with crest factor correction [print this page] Electronic ballast with crest factor correction
In those conventional arts, the low cost electronic ballast with high power factor does not have the capability of regulating the lamp current and so the life span of the lamp is shortened. Moreover, the cost of the electronic ballast having the capable of high power factor and regulating the lamp current simultaneously is very high. One of objectives of the present invention is to provide simple low cost electronic ballast controller for electronic ballast with capable of crest factor correction for efficiently lengthening the life span of a lamp.
Another objective of present invention is employ a electronic ballast controller to correct the crest factor of lamp current for reducing the crest factor of the lamp current.
As aforementioned, the present invention provides an electronic ballast. The electronic ballast comprises a full-wave rectifier, an inverter, a power factor correction means, a voltage signal generator, a controller, a L-C resonant circuit. Wherein when a rectified voltage increases, the inverter increases a resonant frequency of a output AC voltage according to a switch signal for reducing a current passing through a inductor of the L-C resonant circuit, and when the rectified voltage decreases, the inverter decreases the resonant frequency of the output AC voltage according to the switch signal for increasing the current passing through the inductor.
The present invention also provides an electronic ballast with crest factor correction for a fluorescent lamp. The electronic ballast comprises a full-wave rectifier, an inverter, a valley fill circuit, a voltage signal generator, a controller, and a L-C resonant circuit. Wherein when a rectified voltage increases, the inverter increases a resonant frequency of a output AC voltage according to a switch signal for reducing a current passing through a inductor of the L-C resonant circuit, and when the rectified voltage decreases, the inverter decreases the resonant frequency of the output AC voltage according to the switch signal for increasing the current passing through the inductor.
Compared with the low cost electronic ballast with high power factor does not have the capability of regulating the lamp current in those conventional arts and so the life span of the lamp is shortened. On the other hand, the cost of the electronic ballast having the capable of high power factor and regulating the lamp current simultaneously is very high. The present invention employs a voltage feedback signal to adjust the operating frequency for simply controlling the lamp current. Hence, a simple low cost electronic ballast controller with capable of crest factor correction is used for electronic ballast to efficiently reduce the crest factor of the lamp current and lengthen the life span of a lamp.
