Analyze the shortcomings and problems of electroless capacitor LED light engine

In fact, it is very simple to define the light engine: that is, the combination of the LED light source and the LED driving power supply into one module can be called the light engine. Thus it may be more popular, the constant current drive source all the aluminum plate up into the LED light engine becomes.

Some people call the COB LED a light engine, which is obviously wrong! Because it does not have a constant current drive source, there is no "drive", how can it be called "engine"?

The types of power sources can be divided into two categories: DC light engine and AC light engine. However, due to the large number of light engines currently used in indoor lighting, we are paying more attention to the light engine of AC power.

So is the entire LED luminaire also called a light engine? Of course not. Just as the whole car can't be called an engine, the engine is the powertrain of the car, but it doesn't equal the car, and it needs to be added to the car to become a car. Products such as light engines are needed because all lamps have a variety of appearances. Some fixtures can even be called artwork. Take the incandescent lamp, it can be said that it has only one form of the simplest light bulb, at most plus a candle light or a tiny Christmas light. However, its shape can be varied. In particular, the crystal lamp is a variety of arts and crafts, extremely gorgeous. But the LED must also be equipped with an extremely complex constant current drive source to work as an incandescent lamp (it can be illuminated by connecting 220V). If the LED is made into a light engine, it will be brighter when it is connected to 220V like an incandescent lamp (of course, it needs a matching radiator). This on the one hand contributes to standardization and on the other hand greatly facilitates the design of the enclosure (and radiator) designers.

Benefits of using a light engine

Many people believe that the main purpose of promoting light engines is to standardize to increase their interchangeability. In fact, this standardization should not only start with the light engine, but should start with the interface between the unified heat sink and the light engine. In the case of an LED bulb , the size of the light engine and the heat sink is basically the same, and specifically relates to the size position of the positioning screw hole and the positioning screw hole of the heat sink. Even with such specific problems, there are still many difficulties. Because it is related to the wattage and the heat dissipation capability of the heat sink. Therefore, the promotion of the light engine can not only focus on the benefits of interchangeability.

It can be said that the biggest benefits of promoting the light engine are as follows:

1. Reduce the R&D expenses of LED lighting manufacturers and shorten the production cycle

Because the optical and electrical specifications of all LED luminaires are set by the light engine manufacturer. Even the corresponding heat sink is recommended. Lamp manufacturers only need to install the light engine inside the radiator. Lamp manufacturers do not even need experienced optical and electronics engineers, nor do they need to purchase expensive optical and electronic equipment. In other words, the light engine can greatly reduce the entry limit of the LED lighting factory, but it will not reduce the quality of the LED lighting. Of course, this requires the manufacturer of the light engine to have a very high level.

2. Promotion of light engine can greatly accelerate the promotion of LED lamps

In recent years, with the ban on incandescent lamps, LED lamps are about to explode. LED lighting factories have sprung up like mushrooms. Although this is an inevitable trend, it also brings a lot of problems, especially the performance of LED lamps and the disorderly price war between various manufacturers. The emergence of LED light engines can solve such problems to a large extent. Because the quality is determined by several big manufacturers that produce light engines, the price is not likely to have much difference. This greatly reduces the internal friction caused by disorderly competition. Help the rapid development of the LED lighting industry.

3. Improve the overall performance of LED lamps

For example, the overall light efficiency (lm/W) is increased, here is the overall light efficiency including power efficiency, of course, the whole lamp should also include the light transmittance of the lampshade (but this is not the company that produces the light engine). Responsible, but responsible for the company that produces the radiator). It can also increase the color temperature, color rendering index and other indicators.

4. Reduced costs

At least the printed board of the constant current driving source can be omitted, and the production cost thereof.

For now, the simplest and most important is the light engine for LED bulbs. Let's take a look at the composition of this light engine.

LED bulb light engine

For a bulb, its composition is very close to standardization. It consists mainly of three major components: LED light source, constant current drive power supply, heat sink and housing (including lamp holder and lamp cover).

So if you take the LED bulb, if you want to make a light engine, you must combine its power board and LED board into one board. It can be seen that the difficulty is very big.

1, switching power supply is not suitable for light engine

Although the switching power supply has better performance and higher efficiency, the biggest disadvantage is that the number of components is very large, and it is very difficult to integrate with the LED light board. Some people have tried to do this, and the result is very crowded (see Figure 2).

As can be seen from this photo, the entire switching power supply occupies almost 70% of the area, while minimizing the space of the LED. This structure is obviously not feasible because it not only reduces the light-emitting area of ​​the LED, but also blocks part of the light. And the biggest problem is to reduce the heat dissipation area of ​​the LED. It seems likely that there are five 1W LEDs in the picture. If you want to make a 9W or 10W bulb, it is completely impossible to achieve.

2, linear power supply can reduce the number of components but the efficiency is too low

In order to reduce the number of components, the easiest way is to use a linear power supply. Usually, the linear power supply has only 5-6 components, which can greatly reduce the occupied area. At present, most of the light engines on the market are linear constant current sources using electroless capacitors. The electroless capacitor solution was proposed by ExClara in the United States in August 2011. Later, 6-7 companies imitated their ideas. A similar chip. Its basic principle is to connect LED strings driven with different constant current values ​​when inputting different values ​​of the AC voltage waveform to obtain a current waveform matching the half sinusoidal waveform after AC rectification, so that power close to 1 can be obtained. Factor. This can be understood from the internal structure diagram and waveform diagram of this chip. Figure 3 is the internal structure of the CL8801 chip of Supertex Corporation of the United States.

Here are a few light engines that use a non-electrolytic linear constant current source: