Electric lamp and discharge devices: systems – Current and/or voltage regulation
Reexamination Certificate
2000-03-29
2001-07-03
Le, Hoanganh (Department: 2821)
Electric lamp and discharge devices: systems
Current and/or voltage regulation
C315S224000, C315S2090SC
Reexamination Certificate
active
06255785
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a high frequency electronic ballast and particularly to a high power factor electronic ballast with low lamp current peak ratio.
2. Description of Related Art
As is now known in the art, the input power factor of an electronic ballast depends on the distortion of input current thereof. The lower the input current distortion, the higher the input power factor. In the passive type high-power-factor electronic ballasts available today, such as current pursuing type or double pumping type electronic ballasts, their input parameters are out of the range of low distortion requirement in L group standard of IEC 929 and GB/T15144, since their performances are only compliant with H group thereof.
Furthermore, the lamp current peak ratio in current pursuing circuit is larger than 1.7. Thus, the application requiring high power factor with low distortion can not be reached by the electronic ballast described above.
SUMMARY OF THE INVENTION
In view of the above mentioned problems, the object of the invention is to provide a high power factor electronic ballast with low lamp current peak ratio.
The high-power-factor electronic ballast with low lamp current peak ratio according to the invention comprises a bridge rectifier for rectifying the commercial power supply voltage, a high frequency oscillator using the output voltage from the bridge rectifier as its supply voltage, and a first supplementary power source to supply the high frequency oscillator a voltage by superimposing two supplementary voltages generated from a portion of high frequency current in the loads on the output voltage from the bridge rectifier. Further, the electronic ballast comprises a second supplementary power source to supply the high frequency oscillator a direct offset voltage generated from a portion of high frequency current in the load to improve the input current waveform of the bridge rectifier. The second supplementary power source comprises a diode and a capacitor having its one terminal connected to the load terminal, linked with the load and the first supplementary source power, and another terminal connected to the voltage output terminal of the bridge rectifier and linked with one terminal of the diode. The diode is connected serially in a feed branch from the bridge rectifier to the high frequency oscillator with its other terminal connected to the oscillator.
By means of the technical solution according the invention, the purpose of the invention stated above can be attained with simple configuration. In particular, the passive type electronic ballast configured according to the invention has the advantages of low output lamp current peak ratio (<1.7) and high power factor (i.e. with a pf up to 0.97-0.99).
REFERENCES:
patent: 5068573 (1991-11-01), Bruning et al.
patent: 5223767 (1993-06-01), Kulka
patent: 5949199 (1999-09-01), Qian et al.
patent: 6118224 (2000-09-01), Murakami et al.
Yang Changgen
Yu William
Dowell & Dowell , P.C.
Le Hoang-anh
Lee Wilson
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