The fluorescent electronic ballast was developed by Philips Electronics in the early 1980s,
Compared with traditional inductor ballasts,
It is more unique in electrical performance.
Therefore, electronic ballast has a strong vitality.
There are many kinds of circuit design for electronic ballast of fluorescent lamp.
At present, with the rapid development of science and technology,
The design of electronic ballasts for fluorescent lamps tends to be integrated or modular,
To simplify the circuit structure.
Electrical performance is more reliable, stable and safe. The following describes the circuit diagram of the electronic ballast composed of modules and a small number of electronic components.
Hd9712 module is mainly composed of rectifier, current tracking and hierarchical filtering.
The power factor, current peak factor and current harmonic content of fluorescent lamp electronic ballast are collectively referred to as three technical indicators.
It is difficult to reach the standards issued by MIIT at the same time.
The electronic ballast of hd9712 module has reached three targets,
It meets the requirements of "H" in the standard.
Turn on the power supply and input the current into "1, 2" pin of hd9712 circuit through F1 and C1.
After hd9712 circuit rectification, current tracking and graded filtering,
The "3" pin outputs about 300V DC voltage as the working power supply of the ballast,
After R2 depressurization, it is added to C3 and D2 sawtooth wave generators.
C3 and D2 generate sawtooth pulse to trigger the oscillator circuit and make the oscillator work.
After the high frequency voltage with working frequency of 2530khz is sent to L4 and C4 for boosting,
The gas in the fluorescent lamp is ionized and the lamp is on.
At the same time, a small amount of current through C4 circuit plays an auxiliary heating role on the filament to maintain stable lighting.
R5 is a soft starter that can extend the life of the lamp. R1 is the over-voltage protection resistance.