CN211429568U

CN211429568U - LED light system

Info

Publication number: CN211429568U
Application number: CN201921785049.7U
Authority: CN
Inventors: 张会昌; 王岚; 李皛
Original assignee: Liaoning Golden Carbon Management Co ltd
Current assignee: Liaoning Golden Carbon Management Co ltd
Priority date: 2019-10-23
Filing date: 2019-10-23
Publication date: 2020-09-04
Anticipated expiration: 2029-10-23

Abstract

The utility model discloses a LED lighting system, including main circuit, dimmer circuit and feedback circuit, the main circuit with the equal electrical property of dimmer circuit and feedback circuit meets, the main circuit is including the rectifier filter circuit that connects gradually, flyback converter circuit, secondary rectifier circuit and constant current source transform circuit, dimmer circuit includes infrared receiving module and single chip module, infrared receiving module receives infrared information, feeds back to the singlechip, and the LED dimmer system simple structure that designs, stable performance, circuit efficiency height.

Description

LED light system

Technical Field

The utility model relates to a LED device specifically is a LED lighting system.

Background

For the LED light source, the application of the dimming technology can effectively improve the energy saving effect, so the dimming technology driven by the LED is particularly important. In the research of the existing LED dimming technology, the improvement of the LED dimming technology and the application of the LED dimming technology in other mature technologies are mainly focused.

At present, the silicon-controlled dimming is commonly adopted in incandescent lamps and other energy-saving lamps, and the silicon-controlled dimming can be matched to adjust the light, so that the defect that when a silicon-controlled dimmer and an LED lamp are used, if the conduction angle of a silicon-controlled is very small, the LED lamp can be extinguished; the LED lamp may flicker during the adjustment process, especially at the edge where the LED lamp is going to go out. And the wired regulation and control mode needs to reserve the switch position at the construction wall, and regulation and control are inconvenient, and the convenience is relatively poor.

To above problem, the utility model designs a LED dimming system based on swashing transform topology: the method comprises the following steps that (1) a constant current driving power supply based on Boost is adopted, and high efficiency is achieved; (2) the TL494 control chip is adopted to carry out PWM dimming, so that the working performance is stable, the driving capability is strong, and the dimming effect is good; (3) and wireless dimming is realized by adopting infrared remote control.

SUMMERY OF THE UTILITY MODEL

Because of this, the utility model aims to provide a LED lighting system, dimming system simple structure, stable performance, circuit efficiency height.

The LED lighting system comprises a main circuit, a dimming circuit and a feedback circuit, wherein the main circuit is electrically connected with the dimming circuit and the feedback circuit, the main circuit comprises a rectifying and filtering circuit, a flyback conversion circuit, a secondary rectification circuit and a constant current source conversion circuit which are sequentially connected, the dimming circuit comprises an infrared receiving module and a single chip microcomputer module, and the infrared receiving module receives infrared information and feeds the infrared information back to the single chip microcomputer module.

Furthermore, the output of the flyback conversion circuit is connected with the sampling voltage Vom of the negative feedback closed loop to be compared with the reference voltage, the generated error signal controls the conduction time of the Q1, and the output sampling voltage changes along with the reference voltage when the load changes and the input voltage changes.

Further, the constant current source conversion circuit is a constant current driving circuit designed based on Boost, and adopts a switching regulator LM 2577.

Further, the main output end of the LED samples a voltage signal through a voltage division network and inputs the sampled voltage signal to the reference end of the TL 494.

Furthermore, the sampling circuit adopts TL431 and an optical coupler PC817A as reference, isolation and sampling, a pin 2 at the reverse input end of an error amplifier in UC3843 is directly grounded in the circuit, a collector of a triode of the optical coupler PC817A is directly connected to a pin 1 at the output end of the error amplifier, the error amplifier in a chip is skipped, the pin 1 is directly used as feedback, and then the feedback is compared with a pin 3 of current detection input, and a PWM driving signal is output through a latching pulse width modulator.

Further, the PWM control circuit selects a TL494 chip.

Further, STM32 singlechip is selected for the dimming circuit.

Further, the infrared emission module comprises a keyboard matrix, code modulation and an LED infrared transmitter, and a remote control emission circuit of the LED infrared transmitter adopts a TC9012 chip.

The technical effects of the utility model:

the utility model discloses a LED dimming system simple structure, stable performance, circuit efficiency are high to can realize the multistage light modulation to LED, the cost is lower, has solved the inconvenient problem of traditional mechanical switch, has certain practical value.

Drawings

FIG. 1 is a diagram of a power supply system according to the present invention;

fig. 2 is a schematic diagram of a flyback converter of the present invention;

fig. 3 is a constant current source driving circuit of the present invention;

fig. 4 is a feedback circuit of the present invention;

fig. 5 is a control circuit of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The structure of the LED dimming system is shown in fig. 1: the circuit consists of a main circuit, a feedback circuit and a dimming circuit. The main circuit is used for realizing constant current drive of converting alternating current into a direct current stabilized power supply and a load; the feedback circuit samples and feeds back the voltage of the main circuit to realize voltage stabilization; the infrared remote controller in the dimming circuit sends a signal to generate PWM with different duty ratios through TL494 to realize the adjustment of the LED brightness, as shown in fig. 1:

fig. 2 is a main circuit of the flyback converter, which compares the sampled voltage Vom connected to the negative feedback closed loop with the reference voltage, and generates an error signal to control the on-time of Q1, and the output sampled voltage follows the reference voltage when the load and input voltages change. When the Q1 is conducted, the primary winding has current passing, the voltage of Np is constant, the current linearly rises, the rectifier diode D1 is cut off due to reverse bias, therefore, no current passes through the secondary winding, the energy of the primary winding to the secondary winding exists in the form of magnetic energy in the secondary winding, when the Q1 is cut off, the voltage induced by the transformer is just opposite to the input voltage, the diode is conducted in forward bias, the magnetic energy stored in the secondary winding is released to a load circuit in the form of electric energy, and after a few switching cycles, the secondary direct current voltage rises to Vom. When the Q1 is turned off, the NS dotted terminal voltage is positive, the current flows out from the terminal and linearly drops, and drops to zero before the Q1 is turned on again, and the energy stored in the transformer is completely transferred to the load terminal before the Q1 is turned on again.

The constant current driving circuit designed based on the Boost is shown in fig. 3, wherein a control chip of the Boost adopts a switching regulator LM2577, a rated current of an NPN output switch of a switching tube is 3A, a withstand voltage value is 65V, and a wide input voltage range is between 3.5V and 40V, and is used for generating an output voltage higher than an input voltage. The energy storage circuit mainly controls the on-off of a switching tube, and stores energy in an external inductor L at the VIN/L rate. When the switching tube is conducted, the external inductor L stores electric energy in direct proportion to the conduction time of the switching tube; when the switch tube is cut off, the inductor transfers the stored electric energy to the external output capacitor COUT through the external diode D at the speed of (VOUT-VIN)/L. The amount of the output capacitor COUT determines the magnitude of the output voltage. Therefore, the stable output voltage can be obtained by controlling the on-off duty ratio of the switching tube.

The working principle of the constant current driver circuit is as follows: the output current passes through the sampling resistor R3, voltage is generated at two ends of the sampling resistor R3, the voltage is transmitted to the FB pin of the LM2577 after 1/V conversion, and the conduction time of the switch tube is controlled, so that the purpose of controlling the output voltage and the output current is achieved. In the figure, the current IL-OAD passes through a resistor R3, and the voltage across R3:

V_R3＝I_LOAD×R3

because the operational amplifier in the circuit is in deep negative feedback, the positive and negative input terminals have equal potential, so there is V_—＝V₊＝V_R3Because the operational amplifier is short and the input impedance is very large, the current of the input end is almost 0, and the impedance of the output end is very small, thereby achieving the purpose of tracking the input voltage.

The feedback circuit comprises a voltage sampling circuit and a PWM control circuit. After sampling a voltage signal at the main output end of the LED through a voltage division network, inputting the voltage signal to a reference end of TL494, and controlling the current flowing through the light-emitting part of the optical coupler; the optical coupler transmits the feedback signal to the PWM control part, and the PWM control part changes the switching time according to the input feedback signal to realize the voltage stabilization control.

As shown in fig. 4, TL431 is used in cooperation with an optocoupler PC817A for reference, isolation and sampling, in the circuit, a pin 2 at the inverting input end of an error amplifier inside UC3843 is directly grounded, a collector of a triode of PC817A is directly connected to a pin 1 at the output end of the error amplifier, the error amplifier inside a chip is skipped, a pin 1 is directly used as feedback, and then the feedback is compared with a pin 3 of current detection input, and a PWM drive signal is output through a latch pulse width modulator. When the output voltage rises, the voltage rises through the resistor R_up，R_lowThe voltage input to the reference end of the TL431 is increased after voltage division, at the moment, the current flowing through a light emitting diode in the optocoupler is increased, the voltage Vcc of a collecting and emitting stage of a triode PC817A is reduced, the duty ratio of a 6-pin output driving signal of the UC3843 is reduced, and then the output voltage is reduced, so that the purpose of voltage stabilization is achieved.

As shown in fig. 5, in the control circuit implementing the PWM control system, a TL494 chip is selected. The TL494 chip has the characteristics of strong anti-interference capability, simple structure, high reliability, low price and the like. The specific implementation circuit of the control system is shown in FIG. 5. The duty ratio of the PWM output signal is adjusted by adjusting the resistance value of the adjustable resistor, namely changing the set magnitude of the current reference signal, so as to achieve the purpose of adjusting the rotating speed of the motor. The voltage of the power supply is sampled and fed back to a pin 15 of the internal error amplifier 2 of the TL494, and the voltage reference signal is compared with a pin 16 to control the PWM output of the TL494, so that the under-voltage protection function of the system is realized. The system power drive adopts PowerMOSFET, the input impedance of which is very high, and the system power drive can be directly driven by a transistor. The 13 pin of TL494 is used to control the output mode. In the system, the input of the end is selected to be low level, and then two paths of outputs of the trigger in the TL494 have the same frequency as the oscillator, the frequency is the same, and the maximum duty ratio is 98%.

The core chip of the dimming circuit selects the STM32 single chip microcomputer, and the dimming circuit has the advantages of being low in cost, low in power consumption, low in complexity, rich in performance and the like. The adjusting circuit comprises an infrared receiving and transmitting module and a singlechip control module.

The infrared emission module comprises a keyboard matrix, code modulation and an LED infrared transmitter. The remote control transmitting circuit adopts a TC9012 chip. The remote control code generated by the TC9012 is a continuous 32-bit binary code group providing 8 user codes. TC9012 employs pulse width modulation to transmit a duty cycle of the infrared carrier representing "0" and "1". To save energy, the time for emitting the infrared carrier is generally fixed, and the duty cycle is changed by changing the time for not emitting the carrier. The guide code '0' of the TC9012 is 0.56ms transmitted by the carrier and is not transmitted for 0.565ms, and the '1' of the TC9012 is 0.56ms transmitted by the carrier and is not transmitted for 1.69 ms. The output carrier frequency of the transmitting end is 38KHz, and the duty ratio is 1/3.

The integrated infrared receiver IRM338S is an infrared receiving element integrating infrared receiving and amplifying, and comprises a high-speed high-sensitivity PIN photodiode and a low-power-consumption high-gain preamplifier IC output which are matched with TTL and COMS levels, and the low level is effective.

The single chip microcomputer control module comprises a decoding part for the infrared signal and a design for generating a PWM part. The core of decoding is to identify '0' and '1', the '0' and '1' sent to the singlechip start with the low level of 0.56ms, the width of the high level '1' is 1.69ms, and the '0' is 0.56 ms. If the delay is started after 0.56ms low, the bit is "0" if the delay is low, and otherwise the bit is "1". For reliability, the delay time is required to be greater than 0.56ms and less than 1.12ms, and 0.80ms is taken as the most reliable. According to the format of the code, the code is read after the start code and the result code are finished, the single chip microcomputer decodes the 8-bit address, and the change of the PWM duty ratio is further controlled after the decoded record is consistent with the given address code.

The above description is only for the preferred embodiment of the present invention, and the structure is not limited to the above-mentioned shape, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

The LED lighting system is characterized by comprising a main circuit, a dimming circuit and a feedback circuit, wherein the main circuit is electrically connected with the dimming circuit and the feedback circuit, the main circuit comprises a rectifying and filtering circuit, a flyback conversion circuit, a secondary rectifying circuit and a constant current source conversion circuit which are sequentially connected, the dimming circuit comprises an infrared receiving module and a single chip microcomputer module, and the infrared receiving module receives infrared information and feeds the infrared information back to the single chip microcomputer module.
2. The LED lighting system of claim 1, wherein: the output of the flyback conversion circuit is connected with the sampling voltage Vom of the negative feedback closed loop to be compared with the reference voltage, the generated error signal controls the conduction time of the Q1, and the output sampling voltage changes along with the reference voltage when the load changes and the input voltage changes.
3. The LED lighting system of claim 1, wherein: the constant current source conversion circuit is a constant current driving circuit designed based on Boost and adopts a switching regulator LM 2577.
4. The LED lighting system of claim 1, wherein: the main output end of the LED samples a voltage signal through a voltage division network and then inputs the voltage signal to the reference end of the TL 494.
5. The LED lighting system of claim 1, wherein: and the dimming circuit adopts an STM32 singlechip.