The difference between LED street lamps and conventional street lamps is that the LED light source uses low-voltage DC power supply, high-efficiency white light synthesized by GaN-based power blue LEDs and yellow. It has high efficiency, safety, energy saving, environmental protection, long life, fast response, high color rendering index, etc. Unique advantages can be widely used in roads. High temperature resistance up to 135 degrees, low temperature resistance up to -45 degrees. LED street light design has the following requirements:
1. The biggest feature of LEDs for lighting is the function of directional light emission, because almost all power LEDs are equipped with reflectors, and the efficiency of such reflectors is significantly higher than that of lamps.
In addition, the efficiency of the self-reflector has been included in the detection of LED light efficiency.
Road lamps using LEDs should make full use of the characteristics of the directional emitted light of LEDs, so that each LED in the road lamps directly directs light to various areas of the illuminated road surface, and then uses the auxiliary light distribution of the lamp reflector to achieve Very reasonable comprehensive light distribution of road lamps.
It should be said that road lamps must truly meet the illuminance and illuminance uniformity requirements of CJJ45-2006 and CIE31 and CIE115 standards. The luminaire should include the function of three times light distribution in order to achieve better. The LEDs with reflectors and reasonable beam output angles themselves have a good primary light distribution function.
In the lamp, the installation position of each LED and the direction of the emitted light can be designed according to the height of the road lamp and the width of the road surface to achieve a good secondary light distribution function. The reflector in this type of lamp is only used as an auxiliary third light distribution method to ensure better uniformity of road illumination.
When determining the power and beam output angle of each LED, according to E (lx) = I (cd) / D (m) 2 (the law of inverse square ratio of light intensity and illuminance distance), calculate the basic selection of each LED separately The power that should be available at the beam output angle, and the light output of each LED can reach the expected value by adjusting the power of each LED and the different power output from the LED drive circuit to each LED.
These adjustment methods are unique to road lamps that use LED light sources. Taking full advantage of these features can achieve a reduction in lighting power density and energy saving on the premise of satisfying the illuminance and uniformity of road surfaces.
2. The power supply system of LED street lamps is also different from traditional light sources. The constant current drive power required by LEDs is a cornerstone to ensure their normal operation. Simple switching power supply solutions often cause damage to LED devices.
How to make a group of LEDs tightly packed together safe is also an indicator for investigating LED street lights. The requirement of the LED on the drive circuit is to ensure the characteristics of constant current output. Because the relative change area of ​​the junction voltage during the forward operation of the LED is very small, the constant of the LED drive current and the constant output power of the LED are basically guaranteed.
For the current situation of unstable power supply in China, it is very necessary for the driving circuit of the road lamp LED to have a constant current output characteristic, which can ensure a constant light output and prevent the LED from running over power.
To make the LED drive circuit exhibit constant current characteristics, the output internal impedance must be high from the output end of the drive circuit.
During operation, the load current also passes through this output internal impedance. If the drive circuit is composed of a DC constant current source circuit after buck, rectification and filtering, or a general switching power supply plus a resistance circuit, it must also consume a lot of active power on it. Power, so the efficiency of these two types of drive circuits can not be high under the premise of basically meeting the constant current output.
The correct design scheme is to use active electronic switching circuits or high-frequency currents to drive LEDs. Using the above two schemes can make the drive circuit still have high conversion efficiency while maintaining good constant current output characteristics.
The road lamps in China basically adopt the mode of HID light source plus trigger and inductive ballast. Although this mode has the problems of low energy efficiency and strobe. An important aspect that threatens the plasticity of LED lamps that use electronic drive circuits when used in outdoor lighting is the lightning induction problem.
As we all know, the lightning in the air emits a broad spectrum of radio waves, and the overhead road lamp power supply line is well-accepted for wireless.
The radio waves emitted by the same lightning received by the two power lines are common-mode interference signals to the drive circuit. This common-mode interference can reach hundreds of volts to thousands of volts to the ground, and it is easy to break through the drive circuit. EMC grounding capacitors or small electrical clearances to the ground (to the housing) cause damage to the drive circuit.
In addition, because China's power supply line is a three-phase four-wire neutral grounded polar power supply, at the instant when a radio wave of lightning is induced in each section of the two overhead power supply lines, due to the two power supply lines to the ground The difference in instantaneous impedance causes a differential mode interference voltage between the two power supply lines. This instantaneous differential mode interference voltage can also reach hundreds of volts to more than 3000 volts. This voltage often breaks the power supply rectifier diode and printed circuit of the drive circuit. The LED controller will also damage the drive circuit due to the electrical gap between electrodes of different polarities on the circuit board.
Yangzhou solar street lamp manufacturers, solar street lamp prices, the price of various series of street lamp consultation telephone is the same
Website: http: //
Outdoor Landscape Lights,Outdoor Led Motif Lights,Solar Led Motif Lights,Outdoor Solar Garden Lamp
Tianjin Jinji Optoelectronic Technology Co., Ltd. , https://www.tjjjgd.com