The principle of the rectifier
The inductance ballast When the switch is closed circuit of 220 v, 50 hz ac power, the electric current flows through the ballast, lamp filament to the starter filament heating (at the beginning of the starter is broken, due to exert a greater than 190 v ac voltage, the starter has jump of gas inside the bubble inside the arc discharge, the bimetallic strip heating deformation, two electrodes together, form a path to the filament heating), when the starter of the two electrodes together, since there is no arc discharge, bimetallic strip cooling, poles apart, due to the inductance ballasts are perceptual, when the circuit is suddenly interrupted, duration on both ends of the lamp will produce about 1 ms pulse voltage 600 v to 600 v, the exact voltage value depends on the kind of light, in the case of discharge, the ends of the lamp voltage drop, immediately the lamp current limiting effect on the ballast on the one hand, on the other hand make the supply voltage and the working current of the lamp produces 55. - 65. The phase difference of the lamp, which keeps the lamp's secondary start voltage, makes the lamp more stable.
Inductance ballast because of its simple structure, coordination as the first kind of fluorescent lamp ballasts, its market share is still relatively large, because of its low power factor, low voltage startup performance is poor, heavy energy consumption, stroboscopic, and many other shortcomings, its market is slowly being replaced by electronic ballast, the inductance ballast energy loss: 40 w (lamp power) + 10 w heat loss itself (ballast) is equal to the total power consumption of lamps and lanterns of a complete set of 50 w.
In two basic types of rectifier, based on a large power diode or thyristor, the voltage ac power of the grid is converted to dc power by the rectifier. Referred to in the future, near or far) other types of rectifier, on the basis of the uncontrolled diode cutting-edge products of chopper, chopping dc/dc converter or a current source inverter active rectifier. Obviously, this is the latest rectifier contains more on technology to the development of content, but it can show the advantages, for example it in a very small harmonic interference and 1 the power factor of load in power grid.
Electronic ballast is a converter that converts the frequency ac power to high frequency ac power supply. The mains power supply is converted into a dc power source by rf interference (RFI) filter, full wave rectifier and passive (or active) power factor corrector (PPFC or APFC). Through the DC/AC converter, the output of 20 k - 100 KHZ high frequency AC power, added to the LC series resonance circuit, which is connected with lamp heating filament, but make tubes "discharge" "conduction" state, then enter a state of luminescence, high frequency inductive limit the increase of current role at this time, guarantee the normal work of the tubes for the lamp voltage and lamp current, in order to improve the reliability, often add various protection circuit, such as abnormal protection and surge voltage and current protection, temperature protection and so on.
