Analysis on the efficiency and heat dissipation of professional dimming system

Light is the life of TV art. The safety and reliability of the dimming system is a powerful guarantee for shaping the objective world with light. The power of any professional dimming system is very large, a single light bulb is 5kW or even 10kW, and a performance can use thousands of light bulbs. It can be seen that the total power consumption of a dimming system is staggering. Therefore, the efficiency and heat dissipation of the dimming system are very important, which is the key to maintaining the reliability of the dimming system for a long time.
Dimming equipment has gone through four generations: the first generation is a resistive dimmer. The second generation is a transformer-type dimming device. The third generation is the electromagnetic amplifier type dimming device. The fourth generation is the thyristor dimming device. The first generation is the least efficient and the fourth generation is the most efficient.
If the efficiency of the dimming system is not high, the power consumed by itself is considerable. Assuming it’s 96% efficient (which already seems like a pretty good number), when it’s trying to drive a 6kW load, its own power consumption is already:
6×(100%-96%)=0.24kW
Assuming that a dimming vertical cabinet has 60 loads of 6kW, then its total power consumption is as high as:
0.24×60＝14.4kW
Therefore, it is very important to improve the efficiency of the dimming system. It not only reduces the temperature rise of the dimming cabinet (because the temperature rise is directly proportional to the power consumption), but also reduces the power consumption, thereby reducing the operating cost. Currently, more advanced dimming systems use the latest solid state switches and are highly efficient.
The choke coil, whose efficiency is as high as 98%, reduces the great interference caused by the sharp rise of the current due to non-100% dimming. (The thyristor adjusts the voltage by changing the conduction angle, and its conduction time is only about 1μs. This current waveform is actually a pulse with a very steep front.)
However, even with a very efficient dimming system, the performance and design of the cooling system are still very important. Even with 98% efficiency, taking the above as an example, its own power consumption is still as high as 7.2kW. In order to effectively drain such a large power consumption out of the system and keep the internal components of the system working in a reasonable temperature environment, the rational design of the cooling system cannot be ignored.
At present, there are three types of cooling systems for vertical cabinets popular in the world: forced air supply, forced ventilation and intelligent ventilation.
(1) Forced air supply
This heat dissipation system is to install the blower at the bottom of the cabinet, so that the fresh air enters from the bottom of the cabinet and accelerates to blow upwards, thereby taking away the heat generated by the thyristor.
The advantage of this approach is that it is highly efficient, and a large amount of heat can be removed with a small fan. Its disadvantage is that the cold air drawn in from below is continuously heated by the power consumption of the thyristor on the way up, so the temperature of the top thyristor is much higher than that of the bottom, resulting in the top of the thyristor Reliability and lifetime decrease.
(2) Forced ventilation
The design of this system is to install the exhaust fan on the top of the vertical cabinet. Through proper process design, fresh air enters from the front of each thyristor, and then the hot air is exhausted out of the vertical cabinet through ventilation.
This method, through precision design (fluid dynamics) and rigorous process control, can make the air intake of each thyristor from the top to the bottom roughly the same, so that each thyristor can be controlled at an acceptable Operating within a wide temperature range ensures the reliability of each SCR. But this design also has disadvantages, that is, the wind resistance is relatively large, and the power of the exhaust fan needs to be increased, so the noise is also relatively large.
(3) Intelligent ventilation
Because under normal operating conditions, the dimming system is seldom fully loaded, so the required extraction volume can be relatively reduced. Intelligent ventilation is based on this theory, by detecting the temperature rise in the cabinet, and then determining the ventilation volume, under normal operating conditions, the fan only needs to run at a low speed, and the noise is relatively low, but when the load increases, the fan speeds up accordingly. In this way, the advantage of forced ventilation is preserved, and the disadvantage of high noise is also solved.
Finally, it is worth mentioning that although there is a high dimming efficiency and a good heat dissipation system, the dimming system is always a very powerful electrical system. Phenomena such as high temperature and arc ignition cannot be completely avoided. Only on the basis of high efficiency and good heat dissipation, supplemented by necessary anti-high temperature and fire prevention measures (such as using high temperature flame retardant wires), can the safe use of the entire dimming system be guaranteed