The wavelength of plant lights is very suitable for the growth, flowering and fruiting of plants. Generally, indoor plants and flowers will grow worse and worse with time. The main reason is the lack of light irradiation. The LED lamps suitable for the required spectrum of plants are irradiated, not only It can promote its growth, and it can also extend the flowering period and improve the quality of the flowers. The application of this high-efficiency light source system to agricultural production such as greenhouses, greenhouses and other facilities on the one hand can solve the shortcomings of the lack of sunlight leading to the decrease in the taste of tomatoes, cucumbers and other greenhouse vegetables, and on the other hand, it can also advance the winter solanum vegetables in the greenhouse. It will be listed around the Spring Festival, so as to achieve the purpose of off-season cultivation.
Since the junction temperature can be determined by the average power consumption, even a large ripple current has little effect on power consumption. For example, in a buck converter, a peak-to-peak ripple current equal to the DC output current (Ipk-pk=Iout) will increase the total power loss by no more than 10%. If the above loss level is far exceeded, then the AC ripple current from the power supply needs to be reduced in order to keep the junction temperature and operating life constant. A very useful rule of thumb is that for every 10 degrees Celsius decrease in junction temperature, semiconductor lifetime will increase twice. In fact, due to the inhibitory effect of inductors, most designs tend to have lower ripple currents. In addition, the peak current in the LED should not exceed the maximum safe working current rating specified by the manufacturer.
When driving an LED through a buck regulator, the LED often conducts the AC ripple current and DC current of the inductor according to the selected output filter arrangement. This will not only increase the RMS amplitude of the current in the LED, but also increase its power consumption. This can increase the junction temperature and have an important impact on the life of the LED. If we set a 70% light output limit as the lifetime of the LED, the lifetime of the LED will be extended from 15,000 hours at 74 degrees Celsius to 40,000 hours at 63 degrees Celsius. The power loss of the LED is determined by the LED resistance multiplied by the square of the RMS current plus the average current multiplied by the forward voltage drop.
When it is lower than the LED turn-on threshold (the turn-on voltage threshold of a white light LED is about 3.5V), the current passing through the LED is very small. Above this threshold, the current will increase exponentially in the form of a forward voltage. This allows the LED to be shaped as a voltage source with a series resistor, with a warning note: this model is only valid under a single working DC current. If the DC current in the LED changes, then the resistance of the model should also change immediately to reflect the new operating current. Under a large forward current, the power dissipation in the LED will cause the device to heat up, which will change the forward voltage drop and dynamic impedance. It is very important to fully consider the heat dissipation environment when determining the LED impedance.
Adjustable brightness requires a constant current to drive the LED, and the current must be kept constant regardless of the input voltage. This is more challenging than simply connecting an incandescent bulb to a battery to power it.
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