LED lighting is the mainstream of the global energy conservation, and high-power LED lighting is the main trend of the future world of lighting lighting system. High-power LED with high brightness, energy saving and environmental protection, safety and high stability, energy-saving than traditional light sources 60% to 70%.
The traditional sound and light control delay controller can achieve good control of the lights in the dark, or come in the evening when the light comes, can effectively achieve "people to light, people go lights out", but because of its switch is used relay like mechanical controllers, so many places in the flow of people due to frequent switching, relatively easily damaged.
According to the existing high-power led high bay light manufacturers products on the market, designed to be applied in corridors, staircases, classrooms and other places of intelligent lighting systems.
The system uses 24 V / 3 A switching power supply, the lower level can be distributed multiple LED intelligent lighting module (see Figure 1). Controller using AT89C2051, constant current drive using PT4115 chip. Bright lights off and brightness by dimming realization and change.
DIM end PT4115 chip available to achieve the output current PWM dimming from 0-100% adjustment, according to the characteristics, design a set of voice control, light control, time control in one of the intelligent dimming module. Its functions are:
(1) When the light (natural light) time, with or without sound, light does not shine.
(2) When no light (natural light) when, if a man produces sound through the controller to determine the time period, if the sky is completely dark down time (defined as the first period), then the LED emitted 100% brightness. The rest of the time period that the sky still bright, the controller can output a 50% duty cycle square wave, so that the brightness of LED 50% will be issued, which can further save energy, improve energy efficiency.
A constant current driver based PT4115
1. 1 PT4115 chip introduced
PT4115 is a step-down constant current source inductor current continuous conduction mode for driving single or multiple series LED.PT4115 input voltage range of 6 V ~ 30 V, adjustable output current of up to 1. 2A Depending on the input voltage and external components, PT4115 can drive up to tens of watts LED.PT4115 built-in power switch, the use of high-current sample set average LED current, and by D IM pin can accept analog dimming and a wide range of PWM dimming. D IM when the voltage is lower than 0. 3 V, the power switch is turned off, PT4115 enters a low current standby mode.
1. 2 LED spotlights drive circuit
When V IN power-inductance (L) and the current sense resistor (RS) of the initial current is zero, LED output current is zero (see Figure 2). At this time, the output switch is turned on, the potential SW is low. Current through the inductor (L), current sense resistor (RS), LED and internal power switch from V IN to ground, the slope of the current rise from V IN, inductance (L) and LED drop decided to produce a pressure in RS poor VCSN, when (V IN-VCSN) "115 mV, the internal power switch is turned off, the current flowing through the inductor to another slope (L), current sense resistor (RS), LED and Schottky diode (D); as (V IN-VCSN) "when 85mV, power switch back on, which makes the average current in the LED is IOUT = (0. 085+ 0. 015) / 2? RS = 0. 1 / R S. If you do not use the dimming function enables DIM pin floating, then set the maximum output current.
2 Based Top249Y of 72W switching power adapter design
2.1 Transformer Design
High-frequency transformer design should pay attention to: 1) the high-frequency transformer design, at maximum output power, the core of the magnetic flux density should reach saturation, in order to avoid distortion at large signal. 2) In the transient process, the high-frequency leakage inductance and stray capacitance chain will cause inrush current and peak voltage and pulse oscillation top, so the loss increases, the switch will cause serious damage. Meanwhile, the output winding turns and more layers for a long time, you should consider the impact of distributed capacitance, reducing the distributed capacitance help to curb high-frequency signal to interference load. The same high-frequency transformer while reducing the distributed capacitance and leakage inductance is difficult, depending on the job requirements should ensure proper capacitance and inductance.
2.2 switching power supply circuit
Figure 3 C 6 for X-type capacitors, filter series mode interference between the grid. L2 is the common mode suppressor, can filter out common mode interference, C 1 is the input filter capacitor. Use a resistance value R 11 2MΩ realization undervoltage and overvoltage detection, while providing lower output voltage ripple frequency voltage feedforward.
TOP249Y in this circuit DC voltage range of 100 ~ 450 V, once beyond the voltage range, TOP249Y will automatically shut down. Resistor R 10 20. 5 K using an external resistor value from the current limit set to full peak current is only slightly higher than the low-voltage work, allowing the use of smaller transformer core, while avoiding the start and output load transients the core saturation. VR1 that instantaneous voltage suppression tube model is P6KE200, in parallel with the capacitor C 11 in order to reduce the loss of Zener clamp. Models available for blocking diode D1 UF4006. Target clamping voltage averages about 180 VR 4, R 5, R 6 is the output voltage of the sampling resistor, after sampling and TL431 internal reference voltage to generate an error voltage, and then PC817A optocoupler feedback to the control pin C, and then change the output duty TOP249Y to stabilize the output voltage.
3 AT89C2051 based intelligent controller
Shown, which is mainly composed of a sensor unit, A \ D conversion unit, the controller unit 4 based composition AT89C2051 intelligent controller circuit. AT89C2051 chip for voice and light control signals from the sensor detects the signal data through plastic surgery done after treatment, and then control the LED driver. The circuit of AT89C2051 p3. 0 and p3. 1 as an input signal detecting port, and the remaining 13 ports selectable output control. Software flow chart shown in Figure 5.
4 Summary
led high bay light for sale designed by the author, can effectively monitor, detect changes in the surrounding environment, and promptly closed, open source, and dimming lights. The system as compared with conventional sound and light control delay switch illumination system, not only can save a lot of energy, but its unique dimming module using the electricity efficiency is greatly improved. The system is in the works have a good prospect.
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