Why does China Led High Bay Lights Factory need constant current?

The characteristics of LED lighting materials determine that they are greatly affected by the environment. For example, if the temperature changes, the LED current will increase, and the voltage will increase, and the LED current will also increase. Long-term operation exceeding the rated current will greatly shorten the service life of the LED Plant Light Factory. The LED constant current is to ensure that its operating current value remains unchanged when environmental factors such as temperature and voltage change.
The constant current accuracy of some power supplies on the market is poor, and the constant current solutions such as the popular recommended solutions on LED Plant Light Suppliers have an error of ±8%, and the constant current error is too large. The general requirement is within ±3%. According to the design scheme of 3%. The production power supply needs to be fine-tuned to achieve ±3% error.
Generally, the recommended working voltage of LED is 3.0-3.5V. After testing, most of them work at 3.2V, so the calculation formula based on 3.2V is more reasonable. The total voltage of N lamp beads in series = 3.2* N
For example, the rated working current of LED is 350mA, some factories use it up from the beginning, and design 350mA, in fact, the work heat is very serious under this current, after many comparison tests, it is ideal to design it as 320mA . Minimize heat generation, so that more electrical energy can be converted into visible light energy.
In order to make the LED lamp power supply work in a relatively wide input voltage range of AC85-265V, the LED series-parallel connection method of the lamp board is very important. Try not to use wide voltage, can be divided into AC220V, AC110V as much as possible, so as to ensure the reliability of power supply. Since the current power supply is generally a non-isolated step-down constant current power supply, when the required voltage is 110V, the output voltage should not exceed 70V, and the number of series connections should not exceed 23. When the input voltage is 220V, the output voltage can reach 156V. That is to say, the number of series connection does not exceed 45 strings. The number of parallel connections should not be too large, otherwise the working current will be too large and the power supply will heat up severely. There is also a wide voltage solution, APFC active power compensation is to first use L6561/7527 to raise the voltage to 400V, and then step down, which is equivalent to two switching power supplies. This program is only used under certain conditions.
If the general isolated power supply is made into 15W and placed in the power tube of the LED street lamp, the transformer is very large and it is difficult to put it in. It mainly depends on the space structure and depends on the specific situation. Generally, the isolation can only reach 15W, and the ones exceeding 15W are rare, and the price is very expensive. Therefore, the price-performance ratio of isolation is not high. Generally, non-isolation is the mainstream, and the volume can be made smaller, and the minimum height can be 8mm. In fact, there is no problem if non-isolation safety measures are taken well. If space permits, it can also be used as an isolated power supply.
220*1.414=312V, half of the peak voltage is 156V, on the basis of non-isolation, the output wave is the upper half wave and there is no lower half wave, so the number of LED street light power supply beads in series is the largest. Some customers design the light board first, and then find the power supply. It is difficult to have a suitable power supply, either the current is too large and the voltage is too small (such as 7X1WI>350mA, or V<20V); or the current is too small and the voltage is too high (such as I<200mA or V>25V), the result is Severe heat generation, low efficiency, or insufficient input voltage range. In fact, if you choose the best series-parallel connection, the voltage and current applied to each LED will be the same, but the effect of the power supply will be the best. The best way is to communicate with the power supply manufacturer first and make a tailor-made one. Or produce your own power supply.
The capacity of the electrolytic capacitor at the high voltage side of the isolated input AC220V is generally based on the input power of 1W=1UF, AC110V1W=2UF There are three types of power supply PFC on the market: one is without PFC and no power factor compensation dedicated circuit, and its PF value is generally 0.65 Left and right; the second is the passive power factor compensation PFC circuit, that is, the passive power factor compensation lamp, also known as the flow-by-flow circuit board, which is currently the most widely used and the best reliability, and the PF value is generally around 0.92; It is made with an active active 7527/6561 circuit, that is, active power factor compensation, which is called AC220V in the APFC circuit, and an electrolytic capacitor of the same capacity can be used for AC110V, and 1W=1.5UF is selected. The PF value can reach 0.99. But the cost of this scheme is twice as expensive as the second scheme, and the reliability is slightly worse. So the second option is used more. For passive PFC circuit: also known as valley-filling PFC circuit, its DC operating voltage range is half of the peak value of the AC input voltage. If the input is 220V, its peak value should be less than 45 strings. Therefore, in order to obtain a relatively large power factor, the number of series connection of lamp beads should not be too small, otherwise the optimal working condition will not be achieved. The number of series connection on the isolated power supply is related to the number of turns of the secondary winding, which must be done The power of the power supply must meet the output power. The smaller the operating current of the electronic components within the rated voltage operating range, the longer the heating time will be, and vice versa. LED street light power beads are very sensitive to AC power, the higher the AC power, the worse the light comfort. Generally, an electrolytic capacitor should be used to maintain the voltage, and the AC component of the output voltage should be reduced as much as possible. The capacity of the electrolytic capacitor at the bottom voltage end should not be too small, and the ratio of capacity to output current should be 1UF<1.5MA, otherwise the LED will flicker. The selection of the high-voltage electrolytic capacitor at the input end of the non-isolated type is the same as that of the isolated type, and the capacitance at the output end is selected at 1UF<6MA. The electrolytic capacitor at the output end of the dimming LED power supply must meet 1UF<0.5MA.

SLHBT Series LED High bay Light
■Matters needing attention
■Before installing the lighting fixtures, please read this instruction manual carefully.
■The lighting fixtures should be installed, connected and tested by a certified electrician based on the local regulations.
■Lamps should always be installed or replaced carefully.
■Please check the local voltage in accordance with the product requirements before installation.
■Revamping only can be done when the power is off and the lamp is completely cooled down.
■When clean the lamp, make the power off and let it cool down completely, clean the fixture with a soft cloth and a standard PH neutral detergent, stainless steel should be maintained regularly.
■Don't cover the fixtures with flammable materials.
■Replace should be made by the manufacturer or his service agent or certified electrician in order to avoid a hazard.