Opportunities for China's LED drive power industry are coming
As a supporting industry for LED, the industry dynamics of LED driving power supply are closely related to the demand for LED products.
With the gradual popularization of LED lighting and the improvement of the prosperity of the LED industry, it has brought good growth opportunities to the LED drive power industry.
As far as the current technology is concerned, LED driving power supply has become an indispensable part of LED products due to the mismatch between the civilian standard voltage value and the lower working voltage of LED devices.
The stability of LED driving power supply is an important factor that determines the performance and service life of LED products, especially in the field of outdoor LED lighting with harsh environment (Such as LED street lamp, LED tunnel lamp)
, Need to be able to resist wind and rain, lightning, high temperature and other interference to LED products.
Industry insiders have shown that 60% of LED street lamp necrosis is due to the problem of driving power supply.
The design of LED driving power supply is not difficult, but one must know fairly well.
As long as it is calculated before debugging, measured during debugging, and aged after debugging, I believe anyone can do a good job of LED.
1, LED current size, we all know that LEDripple is too large, LED life will be affected, how much impact, and have not seen any experts said.
I asked the LED factory about this data before, and they said it was acceptable within 30, but it was not verified later. It is recommended to control as little as possible.
If the heat dissipation solution is not good, the LED must be used in derating.
I also hope that some experts can give a specific indicator, otherwise it will affect the promotion of LED.
2. Chip heating, which is mainly aimed at the high voltage drive chip with built-in power modulator.
If the current consumed by the chip is 2mA and a voltage of 300V is applied to the chip, the power consumption of the chip is 0. 6 W, of course, will cause the chip to heat up.
The large current of the drive chip comes from the consumption of the drive power MOS tube. The simple calculation formula is I = cvf (
Considering the resistance benefit of charging, the actual I = 2cvf, where c is the cgs capacitor of the power MOS tube and v is the gate voltage when the Power Tube is on, so in order to reduce the power consumption of the chip, we must find ways to reduce c, v and f.
If c, v and f cannot be changed, please find a way to divide the power consumption of the chip into devices outside the chip, and be careful not to introduce additional power consumption.
To be simpler, consider better heat dissipation.
3. The Power Tube is hot. On this issue, I have also seen someone posting on the forum.
The power consumption of the Power Tube is divided into two parts, switching loss and conduction loss.
It should be noted that in most occasions, especially LED Mains Drive applications, switch damage is much greater than conduction loss.
The switching loss is related to the cgd and cgs of the Power Tube and the driving capability and working frequency of the chip, so the heating of the Power Tube can be solved from the following aspects: a. MOS power tube cannot be selected unilaterally according to the on-resistance, because the smaller the internal resistance, the larger the cgs and cgd capacitors.
For example, the cgs of 1N60 is about 250pF, the cgs of 2N60 is about 350pF, and the cgs of 5N60 is about 1200pF. The difference is too big. When selecting a power tube, it is enough.
B, the rest is the frequency and chip driving capability, here only talk about the influence of frequency.
The frequency is also proportional to the conduction loss, so when the Power Tube heats up, first think about whether the frequency selection is a bit high. Find a way to reduce the frequency!
However, it should be noted that when the frequency decreases, in order to obtain the same load capacity, the peak current must become larger or the inductance must also become larger, which may cause the inductance to enter the saturation region.
If the inductor saturation current is large enough, CCM (Continuous current mode)Change to DCM (Discontinuous current mode), So you need to add a load capacitor.
4. Frequency reduction is also a common phenomenon in the debugging process. Frequency reduction is mainly caused by two aspects.
The ratio of input voltage to load voltage is small and system interference is large.
For the former, be careful not to set the load voltage too high, although the load voltage is high, the efficiency will be high.
For the latter, you can try the following aspects: a, set the small current to a smaller point;
B. Clean wiring, especially the critical path of sense;
C, select the small point of inductance or the inductance of closed magnetic circuit;
D, add RC low-pass filtering, this effect is a bit bad, C consistency is not good, deviation is a bit big, but for lighting should be enough.
No matter how to reduce the frequency, there is no advantage, only the harm, so we must solve it.
Compared with other LED sub-industries, there are relatively few enterprises participating in the LED drive power market, with high industrial concentration and less fierce market competition.
At present, mainland LED drive power supply enterprises are mainly engaged in the production of street lamp drive power supply, and the market for high-power LED street lamp drive power supply is mainly concentrated in large-scale enterprises.
As the market for public lighting such as LED street lamps will grow rapidly in the next few years, the high-power LED driving power supply will continue to grow. In addition, with the volume of indoor lighting, the demand for indoor small compact power supplies will also gradually increase.