Interpretation: Electronic ballasts are applied in stage lighting

With the promotion of green lighting, AC electronic ballasts began to emerge. After the 1990s, electronic ballasts for various gas discharge lamps and various new electric light sources emerged worldwide, forming what is called “green lighting”. "Emerging industries." As the main light source of stage computer lights, gas discharge lamps are equipped with AC electronic ballasts.

The use of conventional inductive ballasts has major drawbacks. When the AC power crosses zero, the lamp will generate fire extinguishing, which will cause the lamp to produce 100Hz illuminating flicker, thereby reducing the luminous efficiency of the lamp. At the same time, the inductive ballast needs to fill the asphalt in order to avoid the vibration of the core, and the result is an audio "click" sound during operation. In addition, the inductive ballast is heavier. Usually, a 1200W magnetic ballast weighs 13 kilograms, and the inductive ballast has large losses, and the heat is severe. When the grid voltage fluctuates, the current of the lamp also fluctuates. When the power supply voltage increases by 10%, the current of the lamp increases by 17%, which will greatly shorten the service life of the lamp and the lamp.

Compared with traditional magnetic ballasts, electronic ballasts have many advantages, such as improved lamp and circuit efficiency, energy saving, easy dimming control, no stroboscopic, and non-inductive ballasts. "å—¡å—¡" sound, the disadvantages of magnetic ballasts can be overcome in electronic ballasts. The electronic ballast is actually a high-frequency self-excited (excited) oscillator, the discharge lamp is the load of the converter, and a series resonant circuit is often set in the load circuit.

The advantages of electronic ballasts are reflected in the following aspects:

1. High-frequency self-excited (excited) oscillatory converter circuit plus this series resonance, its load can be applied to various gas discharge lamps, only changing the capacitance and inductance parameters of the resonant circuit to select the appropriate Q value, which can drive each Different types of gas discharge lamp loads, whether it is a fluorescent lamp with a low ignition voltage or a high-pressure sodium lamp or a metal halide lamp with a very high ignition voltage.

2. The voltage supplied to the lamp by the series resonant load circuit is a high-frequency sine wave. The sinusoidal voltage drives the lamp to make the electrode loss small, and the arc is stable: the high-frequency relative power frequency will increase the luminous efficiency of the lamp by about 15%.

3. The combination of the high frequency converter and the series resonant inductor converts the discharge lamp into a high impedance current source from a low impedance voltage source to achieve choke and constant power supply.

4. Connect the power factor correction circuit (active or passive) on the grid side of the high-frequency converter to increase the power factor of the grid side to 0.95 or more, even up to 0.99.