CN115038212A

CN115038212A - Digital isolation dimming method and circuit for three-phase LED tunnel lamp

Info

Publication number: CN115038212A
Application number: CN202210274786.0A
Authority: CN
Inventors: 徐超; 薛浩; 魏正毅; 屠中烈; 鲁华
Original assignee: Hangzhou Yihuitong Technology Co ltd
Current assignee: Hangzhou Yihuitong Technology Co ltd
Priority date: 2022-03-21
Filing date: 2022-03-21
Publication date: 2022-09-09

Abstract

The invention discloses a digital isolation dimming method and a digital isolation dimming circuit for a three-phase LED tunnel lamp, which comprise a three-phase rectification power supply circuit, a digital input signal conditioning circuit, a single chip microcomputer processing circuit, a dimming signal output circuit and the like, wherein the circuit has the advantages of simple structure, good linearity, convenient use, high reliability and the like, can be used for 485 serial port digital dimming of the three-phase 380V LED tunnel lamp, is matched with a dimming interface of a driving chip of the three-phase 380V LED tunnel lamp through the simple dimming signal output circuit, is compatible with a positive and negative logic dimming method, can realize digital intelligent dimming application, and has the advantages of reliable use, convenient dimming, few peripheral circuits, low cost and the like.

Description

Digital isolation dimming method and circuit for three-phase LED tunnel lamp

Technical Field

The invention relates to the electronic field of tunnel lighting, in particular to a digital isolation dimming method and a digital isolation dimming circuit for a three-phase LED tunnel lamp.

Background

The LED is applied more and more widely as a green and efficient new generation lighting source, the LED lighting technology has the characteristics of high lighting effect, good color rendering, long service life, energy conservation, environmental protection and the like, the traditional lighting technology is continuously replaced, in order to create a more comfortable lighting atmosphere and save energy, the three-phase 380V LED tunnel lamp lighting module is applied, the research on the LED lighting dimming technology is extremely important, the existing three-phase 380V LED tunnel lamp lighting does not have the dimming function generally, the requirement of the tunnel lighting market can not be met, and therefore an isolation dimming method and a circuit for the three-phase 380V LED tunnel lamp are urgently needed.

The invention carries out detailed retrieval through the state intellectual property office official website retrieval service system, obtains the following prior arts, and simply introduces the prior arts so as to better understand the inventive concept of the invention and show the technical advantages and the technical characteristics of the invention.

Prior art 1: CN103108432A, which discloses an LED driver and an LED lighting device having the same; however, the manufacturing cost of the prior art is still high, and the dimming function cannot be realized;

prior art 2: CN103561523A, which discloses a light stroboscopic resistant circuit for high PF alternating current direct drive LED circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 3: CN103716968A, which discloses a road lighting method of converting three-phase alternating current commercial power into direct current high voltage direct-drive LED; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 4: CN104135804A, which discloses a three-phase electric rectification LC high PF filtering DC high voltage direct drive LED circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 5: CN104302072A, which discloses a direct-drive LED lighting system controlled by an integrated control circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 6: CN104302073A discloses a direct-drive LED lighting system controlled by an integrated control circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 7: CN104320890A discloses a high voltage direct-drive LED lighting system; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 8: CN104320891A discloses a direct-drive LED lighting system controlled by an integrated control circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 9: CN104320892A discloses a direct-drive LED lighting system controlled by an integrated control circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 10: CN105305854A discloses an LED lighting driving power supply system for a high voltage ac system; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 11: CN105848380A discloses an LED lighting device and an LED lighting system for three-phase ac power; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 12: CN203120227U discloses a LED ac direct drive circuit controlled by a multi-path low-voltage switch circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 13: CN204145854U discloses a direct-drive LED lighting system controlled by an integrated control circuit; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 14: CN210807736U discloses a discrete SIMO dimming and color-adjusting circuit; however, the wiring of the prior art is complex, and open circuit, short circuit or run-off phenomena still exist;

prior art 15: JP6513162B1 discloses an LED lighting system for the same-phase-A class; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 16: JP2011077009A discloses a LIGHTING SYSTEM OF TUNNEL; however, the wiring of the prior art is complex and does not have the function of PWM signal dimming;

prior art 17: JP2011238395A discloses an ILLUMINATION SYSTEM; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 18: KR1020130007861A discloses the power supply for LED lamp; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 19: US7800876B2 discloses an LED dimming circuit; however, the wiring of the prior art is complex and does not have the function of PWM signal dimming;

prior art 20: US9237626B2 discloses a Dimming drive circuit of alternating current direct-drive LED module; however, the wiring of the prior art is complex and does not have the function of PWM signal dimming;

prior art 21: US9445472B2 discloses a Method and circuit for driving light-emitting diodes from a needle-phase power source; however, the prior art has complex wiring and does not have the dimming function;

prior art 22: US10119691B2 discloses a system and methods for improved lighting Systems; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 23: US20080191642A1 discloses a method and Apparatus for Operating Groups of High-Power Leds; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 24: US20100194298a1 discloses a LED DRIVE DEVICE LED DRIVE METHOD AND LIGHTING SYSTEM; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 25: US20100295458A1 discloses AN AC LED MODELE WITH AN IMPROVED POWER FACTOR; however, the wiring of the prior art is complex, and the dimming function cannot be realized;

prior art 26: CN108366448B discloses a positive or negative logic LED dimming circuit and a driving power supply; however, the wiring of the prior art is complex, and open circuit, short circuit or run-off phenomena still exist;

as will be appreciated by those skilled in the art in light of the foregoing description of the prior art, the following features and problems exist in the prior art:

(1) the LED dimming circuit is complex in wiring and high in cost, and open circuit, short circuit or run-off phenomena still exist;

(2) some prior arts can perform positive logic or negative logic dimming or simultaneously compatible with positive logic and negative logic dimming, but are all used for single-phase 220V alternating current input, and dimming control is performed through a dimming interface of a switching power supply, and a dimming control circuit which is directly matched with the dimming interface of a driving chip and has a simple structure cannot be developed, so that the manufacturing cost is still high, and in the application occasions of mass practical production, the defects of complicated field construction and assembly still exist.

Therefore, it is an urgent problem to design a digital isolation dimming method and circuit for a three-phase LED tunnel lamp.

Disclosure of Invention

In view of the above situation, the present invention provides a digital isolation dimming method and circuit for a three-phase LED tunnel lamp to effectively solve the above problems, in order to overcome the above drawbacks in the prior art, and in particular to overcome the defect that no dimming control circuit with a simple structure matching with the dimming interface of the driving chip exists at present.

Therefore, the technical scheme adopted by the invention is as follows:

a digital isolation dimming circuit for a three-phase LED tunnel lamp comprises a three-phase rectification power supply circuit, a digital input signal conditioning circuit, a single chip microcomputer processing circuit and a dimming signal output circuit, and is characterized in that the input of the three-phase rectification power supply circuit is connected with the input of external three-phase 380V alternating current mains supply, and the output of the three-phase rectification power supply circuit is respectively connected with the digital input signal conditioning circuit, the single chip microcomputer processing circuit and the dimming signal output circuit; an external dimming signal is input to the digital input signal conditioning circuit through an external 485 serial port, the digital input signal conditioning circuit processes the digital input signal and then supplies to the single chip microcomputer processing circuit, the single chip microcomputer processing circuit performs data processing and analysis on the received digital signal and then outputs a PWM (pulse width modulation) digital signal to be supplied to the dimming signal output circuit, and the dimming signal output circuit outputs a dimming signal after corresponding signal processing and supplies to a three-phase 380V LED tunnel lamp.

Further, the three-phase rectification power supply circuit comprises a power frequency transformer T1, a low-voltage rectification circuit, a low-dropout linear voltage regulation LDO circuit, an isolation DC/DC circuit 1 and an isolation DC/DC circuit 2; the power frequency transformer T1 is a transformer for converting alternating current (380V) into alternating current (5V); the low-voltage rectifying circuit comprises a rectifying bridge D1, a voltage stabilizing chip U1, a filter capacitor C1 and a filter capacitor C2; the low dropout linear regulator LDO circuit comprises a regulator chip U2, a filter capacitor C3, a filter capacitor C4, a filter capacitor C5 and a filter capacitor C6; the isolation DC/DC circuit 1 comprises a DC/DC power conversion chip U3, a filter capacitor C7 and a filter capacitor C8, and the isolation DC/DC circuit 2 comprises a DC/DC power conversion chip U4, a filter capacitor C9 and a filter capacitor C10.

Furthermore, the input end of the power frequency transformer T1 is connected to any two of three phases of an external three-phase 380V ac mains input A, B, C, the output end of the power frequency transformer T1 is connected to pin 1 and pin 2 of a rectifier bridge D1, pin 3 of the rectifier bridge D1 is connected to one end of a filter capacitor C1 and one end of a filter capacitor C2, and is connected to pin 1 of a regulator chip U1, pin 4 of the rectifier bridge D1 is used as a power ground GND, the other ends of the filter capacitor C1 and the filter capacitor C2 are connected to a power ground GND, pin 2 of a regulator chip U1 is connected to the power ground GND and is used as a negative terminal GND of a 5V power supply, pin 3 of the regulator chip U1 is used as a positive terminal V5 of the 5V power supply, and is used by the low-dropout linear regulator circuit, the LDO DC/DC circuit 1 and the DC/DC circuit 2; pin 3 of a voltage stabilizing chip U2 is used as the input end of the low-dropout linear voltage stabilizing LDO circuit, is connected with one end of a filter capacitor C3 and a filter capacitor C4, and is connected with a positive end V5 of a 5V power supply, the other ends of the filter capacitor C3 and the filter capacitor C4 are connected with a negative end GND of the 5V power supply, and pin 2 of the voltage stabilizing chip U2 is connected with one end of the filter capacitor C5 and one end of the filter capacitor C6 and is used as a positive end V33 of a 3.3V direct-current power supply for the digital input signal conditioning circuit, the singlechip processing circuit and the dimming signal output circuit; a pin 1 of the voltage stabilizing chip U2 is connected with a negative terminal GND of a 5V power supply and used as the negative terminal GND of a 3.3V direct-current power supply; pin 2 of the DC/DC power conversion chip U3 is connected with one end of the filter capacitor C7 and is connected with the positive terminal V5 of the 5V power supply, pin 1 of the DC/DC power conversion chip U3 is connected with the other end of the filter capacitor C7 and is connected with the negative terminal GND of the 5V power supply, pin 4 of the DC/DC power conversion chip U3 is connected with one end of the filter capacitor C8 and is used as the positive terminal V5D of the 1 st path 5V direct-current power supply for the digital input signal conditioning circuit, pin 3 of the DC/DC power conversion chip U3 is connected with the other end of the filter capacitor C8 and is used as the negative terminal GND1 of the 1 st path 5V direct-current power supply for the digital input signal conditioning circuit; pin 2 of the DC/DC power supply conversion chip U4 is connected with one end of the filter capacitor C9 and is connected with the positive end V5 of the 5V power supply, pin 1 of the DC/DC power supply conversion chip U4 is connected with the other end of the filter capacitor C9 and is connected with the negative end GND of the 5V power supply, pin 4 of the DC/DC power supply conversion chip U4 is connected with one end of the filter capacitor C10 and is used as the positive end V5S of the 2 nd 5V direct-current power supply for the dimming signal output circuit, pin 3 of the DC/DC power supply conversion chip U4 is connected with the other end of the filter capacitor C10 and is used as the negative end GND2 of the 2 nd 5V direct-current power supply for the dimming signal output circuit.

Further, the digital input signal conditioning circuit comprises a 485 serial port conversion chip U5 and an optical coupling isolation circuit.

Further, the optical coupling isolation circuit comprises an optical coupling chip U6, an optical coupling chip U7, an optical coupling chip U8, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a bipolar transistor Q1, a bipolar transistor Q2 and a bipolar transistor Q3.

Further, the 485 serial port conversion chip U5 is an 8-pin chip, and the optical coupler chip U6, the optical coupler chip U7 and the optical coupler chip U8 are 4-pin chips; pin 8 of the 485 serial port conversion chip U5 is connected with the positive terminal V5D of the 1 st 5V DC power supply, pin 7 of the 485 serial port conversion chip U5 is connected with one end of an external 485 serial port input signal, pin 6 of the 485 serial port conversion chip U5 is connected with the other end of the external 485 serial port input signal, pin 5 of the 485 serial port conversion chip U5 is connected with the negative terminal GND1 of the 1 st 5V DC power supply, pin 4 of the 485 serial port conversion chip U5 is connected with pin 4 of the optocoupler chip U8 and one end of a resistor R6, the other end of the resistor R6 is connected with the positive terminal V5D of the 1 st 5V DC power supply, pin 3 and pin 2 of the 485 serial port conversion chip U5 are in short circuit and connected with one end of pin 4 and resistor R9 of the optocoupler chip U7, the other end of the resistor R9 is connected with the positive terminal V5 of the 1 st 5V DC power supply, pin 1 of the 485 conversion chip U636 is connected with the other end of the resistor R3, the base of the resistor R3 is connected with the base of the transistor Q2, a collector of the transistor Q2 is connected with a negative terminal GND1 of the 1 st path 5V direct current power supply, an emitter of the transistor Q2 is connected with a pin 2 of an optocoupler chip U6, a pin 1 of the optocoupler chip U6 is connected with one end of a resistor R2, the other end of the resistor R2 is connected with a positive terminal V5D of the 1 st path 5V direct current power supply, a pin 3 of the optocoupler chip U7 is connected with a negative terminal GND1 of the 1 st path 5V direct current power supply, a pin 3 of the optocoupler chip U8 is connected with a negative terminal GND1 of the 1 st path 5V direct current power supply, and a pin 4 of the optocoupler chip U6 is connected with one end of the resistor R1 and is used as an output RXD of the digital input signal conditioning circuit for use by a singlechip processing circuit; the other end of the resistor R1 is connected with a 3.3V direct-current power supply positive end V33, a pin 3 of the optocoupler chip U6 is connected with a 3.3V direct-current power supply negative end GND, a pin 1 of the optocoupler chip U7 is connected with one end of the resistor R8, the other end of the resistor R8 is connected with a 3.3V direct-current power supply positive end V33, a pin 2 of the optocoupler chip U7 is connected with an emitter of the transistor Q3, a base of the transistor Q3 is connected with one end of the resistor R7, and the other end of the resistor R7 is used as an output RD of the digital input signal conditioning circuit and is used by the single-chip microcomputer processing circuit; the collector of the transistor Q3 is connected with the negative end GND of the 3.3V direct current power supply; pin 1 of the optocoupler chip U8 is connected with one end of a resistor R5, the other end of the resistor R5 is connected with a 3.3V direct-current power supply positive end V33, pin 2 of the optocoupler chip U8 is connected with an emitter of a transistor Q1, a base of the transistor Q1 is connected with one end of the resistor R4, and the other end of the resistor R4 is used as an output TXD of a digital input signal conditioning circuit and is used by a singlechip processing circuit; the collector of the transistor Q1 is connected to the negative terminal GND of the 3.3V DC power supply.

Further, the single chip microcomputer processing circuit comprises a single chip microcomputer MCU chip U9, a filter capacitor C11, a filter capacitor C12 and a resistor R10.

Furthermore, the MCU chip U9 is a single chip with 8 pins, pin 1 of the MCU chip U9 is connected with one end of a resistor R10, the other end of the resistor R10 is connected with the negative terminal GND of a 3.3V direct current power supply, pin 2 of the MCU chip U9 is connected with one end of a filter capacitor C11 and one end of a filter capacitor C12 and is connected with the positive terminal V33 of the 3.3V direct current power supply, the other ends of the filter capacitor C11 and the filter capacitor C12 are connected with the negative terminal GND of the 3.3V direct current power supply, pin 3 of the MCU chip U9 is suspended, pin 4 of the MCU chip U9 is connected with the negative terminal GND of the 3.3V direct current power supply, pin 5 of the MCU chip U9 is connected with the output terminal RXD of the digital input signal conditioning circuit as a serial port communication interface RXD, pin 6 of the MCU chip U9 is connected with the output terminal D of the digital input signal conditioning circuit as a serial port communication interface D, and the serial port RXDRD 7 of the single chip U9 is connected with the digital input signal conditioning circuit as a serial port RD, pin 8 of the MCU chip U9 of the singlechip is used as the output end PWM of the singlechip processing circuit, and the PWM digital signal is output for the dimming signal output circuit to use.

Further, the dimming signal output circuit comprises an optocoupler chip U10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a filter capacitor C13 and a bipolar transistor Q4.

Further, the optical coupling chip U10 is a 4-pin linear optical coupling device, pin 1 of the optical coupling chip U10 is connected to one end of a resistor R12, the other end of the resistor R12 is connected to a 3.3V positive terminal V33 of a direct current power supply, pin 2 of the optical coupling chip U10 is connected to one end of a resistor R11 and a collector of a transistor Q4, the other end of the resistor R11 is connected to one end of a filter capacitor C13 and to a 3.3V positive terminal V33 of the direct current power supply, the other end of the filter capacitor C13 is connected to a 3.3V negative terminal GND of the direct current power supply, the base of the transistor Q4 is connected to the output PWM of the single chip processing circuit, and the emitter of the transistor Q4 is connected to the 3.3V negative terminal GND of the direct current power supply; pin 3 of opto-coupler chip U10 links to each other with the one end of resistance R14, and the output that simultaneously is as dimming signal output circuit, output PWM dimming signal supplies outside three-phase 380V's LED tunnel lamp to use, and the other end of resistance R14 links to each other with 2 nd way 5V DC power supply's negative terminal GND2, and pin 4 of opto-coupler chip U10 links to each other with the one end of resistance R13, and the other termination of resistance R13 is the positive terminal V5S of 2 nd way 5V DC power supply.

Furthermore, the invention also relates to a dimming method of the digital isolation dimming circuit for the three-phase LED tunnel lamp, it is characterized in that the PWM dimming signal output by the dimming signal output circuit is connected with a dimming interface of a driving chip of the AC three-phase 380V LED tunnel lamp, when the dimming is needed, the digital input signal conditioning circuit receives the 485 serial port signal input from the outside, after the 485 serial port conversion and the optical coupling isolation, output to the singlechip processing circuit, after the singlechip processing circuit processes and analyzes the received digital signal, the PWM digital signal is output to a dimming signal output circuit for use, the dimming signal output circuit outputs a dimming signal to a three-phase 380V LED tunnel lamp for use after corresponding signal processing, the output dimming signal is directly connected with a dimming interface of a driving chip of the three-phase 380V LED tunnel lamp.

To sum up, utilized driver chip from the interface of adjusting luminance in area, used the negative logic mode of adjusting luminance: when the dimming control circuit outputs 0% of PWM duty ratio, the output power of the LED lamp is maximum; when the dimming control circuit outputs 100% of PWM duty ratio, the output power of the LED lamp is minimum; when the dimming controller fails to output or outputs 0% of PWM duty ratio, the three-phase 380V LED tunnel lamp can still be in the state of maximum output power, the use of the whole lamp is not influenced, and dimming control can be automatically recovered after the fault is eliminated.

The invention has the advantages that:

1. the simple digital isolation dimming circuit is matched with a dimming interface of a driving chip of the AC three-phase 380V tunnel LED lamp, and the dimming interface of the driving chip of the three-phase 380V tunnel LED lamp is controlled through the change of the PWM signal output duty ratio, so that the dimming function is realized.

2. The invention provides a digital isolation dimming circuit for an LED tunnel lamp with an alternating-current three-phase 380V working voltage, which directly uses an alternating-current three-phase 380V power supply and is the same as a power supply of the three-phase 380V LED tunnel lamp.

3. The digital isolation dimming circuit provided by the invention uses a negative logic dimming mode, solves the problem that the use of the whole lamp is influenced due to the faults of open circuit, short circuit, failure and the like of the dimming controller, can still output the state of the maximum power when the LED lamp cannot receive a normal dimming control signal, does not influence the use of the whole lamp, and can automatically recover the dimming control after the faults are eliminated.

4. The dimming method and the circuit of the digital isolation dimming mode, which are provided by the invention, use the unified 485 digital signal interface dimming circuit, have good compatibility, do not need customers to individually customize the dimming mode, and have the advantages of reliable use, convenient dimming, few peripheral circuits, low cost and the like.

Drawings

Fig. 1 is a block diagram of a digital isolation dimming circuit for a three-phase LED tunnel lamp.

Fig. 2 is a schematic diagram of a three-phase rectification power supply circuit in the embodiment.

Fig. 3 is a schematic diagram of a digital input signal conditioning circuit in an embodiment.

Fig. 4 is a schematic diagram of a single chip processing circuit in the embodiment.

Fig. 5 is a schematic diagram of a dimming signal output circuit in an embodiment.

Detailed Description

The invention is further explained below with reference to the drawings;

the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the installation methods, the communication protocols and the technical terms mentioned in the present invention are technical terms that are already clearly known in the technical field, and therefore, the explanation thereof is not repeated.

The first embodiment is as follows:

as shown in fig. 1, the present embodiment provides a digital isolation dimming method and circuit for a three-phase LED tunnel lamp, including a three-phase rectification power supply circuit, a digital input signal conditioning circuit, a single chip processing circuit, a dimming signal output circuit, etc., where the three-phase rectification power supply circuit includes a transformer, a low-voltage rectification circuit, a low-dropout linear regulator LDO circuit, an isolation DC/DC circuit 1, and an isolation DC/DC circuit 2; the LDO circuit is a low-voltage drop linear voltage-stabilized power supply circuit, an output power supply of the LDO circuit is mainly used by a singlechip processing circuit, the isolation DC/DC circuit 1 is an isolation type direct current to direct current switching power supply circuit, an output power supply of the isolation DC/DC circuit is used by a digital input signal conditioning circuit, and the isolation DC/DC circuit 2 is also an isolation type direct current to direct current switching power supply circuit, and an output power supply of the isolation DC/DC circuit is used by a dimming signal output circuit. The connection among the specific circuits is shown in fig. 1, wherein the input of the three-phase rectification power supply circuit is connected with the input of an external three-phase 380V alternating current commercial power, the output of the three-phase rectification power supply circuit is respectively connected with the digital input signal conditioning circuit, the single chip processing circuit and the dimming signal output circuit to provide a direct current stabilized power supply for the three-phase 380V alternating current commercial power, an external dimming signal is input to the digital input signal conditioning circuit through an external 485 serial port and is used by the single chip processing circuit after being processed by the digital input signal conditioning circuit, the single chip processing circuit outputs a PWM digital signal to the dimming signal output circuit after performing data processing and analysis on the received digital signal, and the dimming signal output circuit outputs a dimming signal to the three-phase 380V LED tunnel lamp after corresponding signal processing.

As shown in fig. 2, the three-phase rectification power supply circuit includes a power frequency transformer T1, a low-voltage rectification circuit, a low dropout linear regulator LDO circuit, an isolation DC/DC circuit 1, and an isolation DC/DC circuit 2; wherein, the power frequency transformer T1 is a transformer for converting an alternating current 380V into an alternating current 5V, the low voltage rectification circuit is composed of a rectification bridge D1, a voltage stabilization chip U1, filter capacitors C1 and C2, the low voltage difference linear voltage regulation LDO circuit is composed of a voltage stabilization chip U2, a filter capacitor C3, C4, C5 and C6, the isolation DC/DC circuit 1 is composed of a DC/DC power conversion chip U3, a filter capacitor C7 and C8, the isolation DC/DC circuit 2 is composed of a DC/DC power conversion chip U4, a filter capacitor C9 and C10, the specific circuit connection is as shown in fig. 2, wherein, an input end of the power frequency transformer T1 is connected with any two phases of an external three-phase 380V alternating current mains supply input A, B, C, such as an a phase 380VA and a phase 380VB, an output end of the transformer T1 is connected with a pin 1 and a pin 2 of the rectification bridge D1, a pin 3 of the rectification bridge D1 is connected with one end of the filter capacitor C1 and C2, the output end of the voltage stabilizing chip U1 is connected with a pin 1 of a voltage stabilizing chip U1, a pin 4 of a rectifier bridge D1 is used as a power ground GND, the other ends of filter capacitors C1 and C2 are connected with the power ground GND, a pin 2 of the voltage stabilizing chip U1 is connected with the power ground GND and is used as a negative end GND of a 5V power supply, and a pin 3 of the voltage stabilizing chip U1 is used as a positive end V5 of the 5V power supply and is used by the LDO circuit, the isolation DC/DC circuit 1 and the isolation DC/DC circuit 2; pin 3 of the voltage stabilizing chip U2 is used as the input end of the LDO circuit, is connected with one end of a filter capacitor C3 and C4 and is connected with the positive end V5 of a 5V power supply, the other end of the filter capacitor C3 and C4 is connected with the negative end GND of the 5V power supply, pin 2 of the voltage stabilizing chip U2 is connected with one end of the filter capacitor C5 and C6 and is used as the positive end V33 of a 3.3V direct current power supply for the digital input signal conditioning circuit, the singlechip processing circuit and the dimming signal output circuit, pin 1 of the voltage stabilizing chip U2 is connected with the negative end GND of the 5V power supply and is used as the negative end GND of the 3.3V direct current power supply. Pin 2 of the DC/DC power supply conversion chip U3 is connected with one end of a filter capacitor C7 and is connected with the positive end V5 of a 5V power supply, pin 1 of the DC/DC power supply conversion chip U3 is connected with the other end of the filter capacitor C7 and is connected with the negative end GND of the 5V power supply, pin 4 of the DC/DC power supply conversion chip U3 is connected with one end of a filter capacitor C8 and is used as the positive end V5D of the 1 st 5V direct-current power supply for the digital input signal conditioning circuit, pin 3 of the DC/DC power supply conversion chip U3 is connected with the other end of the filter capacitor C8 and is used as the negative end GND1 of the 1 st 5V direct-current power supply for the digital input signal conditioning circuit. Pin 2 of the DC/DC power conversion chip U4 is connected with one end of the filter capacitor C9 and is connected with the positive end V5 of the 5V power supply, pin 1 of the DC/DC power conversion chip U4 is connected with the other end of the filter capacitor C9 and is connected with the negative end GND of the 5V power supply, pin 4 of the DC/DC power conversion chip U4 is connected with one end of the filter capacitor C10 and is used as the positive end V5S of the 2 nd 5V direct-current power supply for the light modulation signal output circuit, pin 3 of the DC/DC power conversion chip U4 is connected with the other end of the filter capacitor C10 and is used as the negative end GND2 of the 2 nd 5V direct-current power supply for the light modulation signal output circuit.

As shown in fig. 3, the digital input signal conditioning circuit includes a 485 serial port conversion chip U5 and an optical coupling isolation circuit, wherein the optical coupling isolation circuit is composed of an optical coupling chip U6, U7, U8, resistors R1, R2, R3, R4, R5, R6, R7, R8, R9, and bipolar transistors Q1, Q2, and Q3, and the specific circuit connection is as shown in fig. 3, wherein the 485 serial port conversion chip U5 is a chip with 8 pins, and the optical coupling chips U6, U7, and U8 are chips with 4 pins; pin 8 of the chip U5 is connected with positive terminal V5D of the 1 st 5V DC power supply, pin 7 of the chip U5 is connected with one end of an external 485 serial port input signal, pin 6 of the chip U5 is connected with the other end of the external 485 serial port input signal, pin 5 of the chip U5 is connected with negative terminal GND1 of the 1 st 5V DC power supply, pin 4 of the chip U5 is connected with pin 4 of the optocoupler chip U8 and one end of a resistor R6, the other end of the resistor R6 is connected with positive terminal V5D of the 1 st 5V DC power supply, pin 3 and pin 2 of the chip U5 are shorted, and are connected with pin 4 of the optocoupler chip U7 and one end of a resistor R9, the other end of the resistor R9 is connected with positive terminal V5D of the 1 st 5V DC power supply, pin 1 of the chip U5 is connected with one end of a resistor R3, the other end of the resistor R3 is connected with base of the transistor Q2, and collector of the transistor Q2 is connected with GND1 of the 1 st 5V 965V DC power supply, an emitter of the transistor Q2 is connected with a pin 2 of the optical coupling chip U6, a pin 1 of the optical coupling chip U6 is connected with one end of a resistor R2, the other end of the resistor R2 is connected with a positive terminal V5D of a1 st 5V direct current power supply, a pin 3 of the optical coupling chip U7 is connected with a negative terminal GND1 of the 1 st 5V direct current power supply, a pin 3 of the optical coupling chip U8 is connected with a negative terminal GND1 of the 1 st 5V direct current power supply, a pin 4 of the optical coupling chip U6 is connected with one end of a resistor R1 and is used as an output RXD of the digital input signal conditioning circuit for a singlechip processing circuit, the other end of the resistor R1 is connected with a positive terminal V33 of a 3.3V direct current power supply, a pin 3 of the optical coupling chip U6 is connected with a negative terminal GND of the 3.3V direct current power supply, a pin 1 of the optical coupling chip U7 is connected with one end of a resistor R8, the other end of the resistor R8 is connected with a positive terminal V direct current power supply V3, and a pin 33 of the optical coupling chip U7 is connected with an emitter of the optical coupling chip Q3Q 7, the base electrode of the transistor Q3 is connected with one end of the resistor R7, the other end of the resistor R7 is used as the output RD of the digital input signal conditioning circuit and is used by a single chip processing circuit, and the collector electrode of the transistor Q3 is connected with the negative end GND of a 3.3V direct-current power supply; pin 1 of the optocoupler chip U8 is connected with one end of a resistor R5, the other end of the resistor R5 is connected with a 3.3V direct-current power supply positive end V33, pin 2 of the optocoupler chip U8 is connected with an emitter of a transistor Q1, a base of a transistor Q1 is connected with one end of the resistor R4, the other end of the resistor R4 is used as an output TXD of a digital input signal conditioning circuit and is used by a singlechip processing circuit, and a collector of the transistor Q1 is connected with a 3.3V direct-current power supply negative end GND;

as shown in fig. 4, the single chip microcomputer processing circuit is composed of a single chip microcomputer MCU chip U9, filter capacitors C11, C12, and a resistor R10, and the specific circuit connection is as shown in fig. 4, wherein the single chip microcomputer MCU chip U9 is an 8-pin single chip microcomputer, pin 1 of the single chip microcomputer MCU chip U9 is connected to one end of the resistor R10, the other end of the resistor R10 is connected to the 3.3V dc power supply negative terminal GND, pin 2 of the single chip microcomputer MCU chip U9 is connected to one ends of the filter capacitors C11 and C12 and is connected to the 3.3V dc power supply positive terminal V33, the other ends of the filter capacitors C11 and C12 are connected to the 3.3V dc power supply negative terminal GND, pin 3 of the single chip microcomputer MCU chip U9 is suspended, pin 4 of the single chip MCU chip U9 is connected to the 3.3V dc power supply positive terminal V dc power supply negative terminal V GND, pin 5 of the MCU chip U9 is connected to the serial port communication interface RXD and the output terminal of the single chip RXD conditioning circuit, and the serial port communication interface TXD of the single chip TXD is connected to the serial port of the single chip TXD circuit, pin 7 of the single-chip microcomputer MCU chip U9 is used as a serial port communication interface RD to be connected with an output end RD of the digital input signal conditioning circuit, and pin 8 of the single-chip microcomputer MCU chip U9 is used as an output end PWM of the single-chip microcomputer processing circuit to output PWM digital signals for the dimming signal output circuit to use.

As shown in fig. 5, the dimming signal output circuit is composed of an optocoupler chip U10, resistors R11, R12, R13, R14, a filter capacitor C13, and a bipolar transistor Q4, and the specific circuit connection is as shown in fig. 5, wherein the optocoupler chip U10 is a 4-pin linear optocoupler, pin 1 of the optocoupler chip U10 is connected to one end of a resistor R12, the other end of the resistor R12 is connected to a 3.3V dc power positive terminal V33, pin 2 of the optocoupler chip U10 is connected to one end of a resistor R11 and a collector of the transistor Q4, the other end of the resistor R11 is connected to one end of a filter capacitor C13 and to a 3.3V dc power positive terminal V33, the other end of the filter capacitor C13 is connected to a 3.3V dc power negative terminal GND, the base of the transistor Q4 is connected to an output terminal of the PWM processing circuit, and the emitter of the transistor Q4 is connected to a 3.3V dc power negative terminal GND; pin 3 of the optocoupler chip U10 is connected with one end of a resistor R14 and is used as an output end of a dimming signal output circuit to output a PWM dimming signal to an external three-phase 380V LED tunnel lamp, the other end of the resistor R14 is connected with a negative end GND2 of a 2 nd path 5V direct-current power supply, pin 4 of the optocoupler chip U10 is connected with one end of a resistor R13, and the other end of the resistor R13 is connected with a positive end V5S of the 2 nd path 5V direct-current power supply. The dimming signal output by the dimming signal output circuit is connected with a dimming interface of a driving chip of an alternating current three-phase 380V LED tunnel lamp, when dimming is needed, the digital input signal conditioning circuit receives 485 serial port signals input from the outside, the 485 serial port signals are output to the single chip processing circuit after being converted and optically coupled and isolated, the single chip processing circuit carries out data processing and analysis on the received digital signals, the PWM digital signals are output to the dimming signal output circuit for use, the dimming signal output circuit outputs dimming signals to the three-phase 380V LED tunnel lamp after corresponding signal processing, the output dimming signals are directly connected with the dimming interface of the driving chip of the three-phase 380V LED tunnel lamp, the power change of the LED tunnel lamp is controlled through the change of the duty ratio of the output dimming signals, and therefore the dimming function is achieved.

The second embodiment:

similar to the embodiment, the digital isolation dimming method and circuit for the three-phase LED tunnel lamp in the embodiment comprises a three-phase rectification power supply circuit, a digital input signal conditioning circuit, a single chip microcomputer processing circuit, a dimming signal output circuit and the like,

the three-phase rectification power supply circuit comprises a power frequency transformer T1, a low-voltage rectification circuit, an LDO circuit, an isolation DC/DC circuit 1 and an isolation DC/DC circuit 2; the output power supply V33 and GND of the LDO circuit are used by a singlechip processing circuit, the isolation DC/DC circuit 1 is an isolation type direct current to direct current power supply circuit, the output power supply V5D and GND1 of the isolation DC/DC circuit are used by a digital input signal conditioning circuit, the isolation DC/DC circuit 2 is also an isolation type direct current to direct current power supply circuit, and the output power supply V5S and GND2 of the isolation DC/DC circuit are used by a dimming signal output circuit. The connections between specific circuits are shown in fig. 1.

The power frequency transformer T1 is a transformer for converting 380V alternating current into 5V alternating current, a rectifier bridge D1 in a low-voltage rectification circuit is MB6F, a voltage stabilizing chip U1 is LM7805, filter capacitors C1 and C2 are patch capacitors of 10uF/25V and 0.1uF/25V respectively, a voltage stabilizing chip U2 in a low-voltage-difference linear voltage stabilizing LDO circuit is AMS1117-3.3V, filter capacitors C3 and C5 are patch capacitors of 10uF/25V, filter capacitors C4 and C6 are patch capacitors of 0.1uF/25V, a DC/DC power conversion chip U3 in an isolation DC/DC circuit 1 is B0505S-1W, filter capacitors C7 and C8 are patch capacitors of 10uF/25V and 0.1uF/25V respectively, a DC/DC power conversion chip U4 in an isolation DC/DC circuit 2 is B635W, filter capacitors C4 in B635W, filter capacitors C S and C638 are patch capacitors of 10 uF/05025V respectively, and filter capacitors of 0.10 uF/638, The specific circuit connection of the 0.1uF/25V patch capacitor is shown in figure 2. The model of a 485 serial port conversion chip U5 in the digital input signal conditioning circuit is SP485, the models of optical coupling chips U6, U7 and U8 in the optical coupling isolation circuit are EL3H7, resistors R1, R2, R3, R4, R5, R6, R7, R8 and R9 are 0805 chip packaging resistors with 1K ohm, the models of transistors Q1, Q2 and Q3 are S8550, and the specific circuit connection is as shown in FIG. 3; the model of a singlechip MCU chip U9 in the singlechip processing circuit is STC8G1K08A, filter capacitors C11 and C12 are respectively 1uF/25V and 0.01uF/25V patch capacitors, a resistor R10 is a 0805K ohm patch packaging resistor, and the specific circuit connection is as shown in FIG. 4; the type of an optocoupler chip U10 in the dimming signal output circuit is EL3H7, resistors R11, R12, R13 and R14 are 0805 chip packaging resistors with 510 ohms, a filter capacitor C13 is a chip capacitor with 1uF/25V, and the type of a transistor Q4 is S8550; the PWM dimming signal output by the dimming signal output circuit is directly connected with a dimming interface of a driving chip of an alternating-current three-phase 380V LED tunnel lamp, when dimming is needed, the digital input signal conditioning circuit receives 485 serial port signals input externally, the signals are output to the single chip microcomputer processing circuit after 485 serial port conversion and optical coupling isolation, the single chip microcomputer processes and then outputs the PWM signal, then the PWM signal is output through the dimming signal output circuit, the output dimming signal is used by the dimming interface of the driving chip of the three-phase 380V LED tunnel lamp, the power change of the LED tunnel lamp is controlled through the change of the duty ratio of the dimming signal, and therefore the dimming function is achieved.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any minor modifications, equivalent replacements and improvements made to the above embodiment according to the technical spirit of the present invention should be included in the protection scope of the technical solution of the present invention.

Claims

1. The utility model provides a digital isolation dimming circuit for three-phase LED tunnel lamp, includes three-phase rectification supply circuit, digital input signal conditioning circuit, singlechip processing circuit, dimming signal output circuit, its characterized in that: the input of the three-phase rectification power supply circuit is connected with the input of an external three-phase 380V alternating current commercial power, and the output of the three-phase rectification power supply circuit is respectively connected with the digital input signal conditioning circuit, the single chip microcomputer processing circuit and the dimming signal output circuit; an external dimming signal is input to the digital input signal conditioning circuit through an external 485 serial port and is used by the single chip microcomputer processing circuit after being processed by the digital input signal conditioning circuit, the single chip microcomputer processing circuit performs data processing and analysis on the received digital signal and outputs a PWM (pulse width modulation) digital signal for the dimming signal output circuit, and the dimming signal output circuit outputs a dimming signal for the three-phase 380V LED tunnel lamp after corresponding signal processing.

2. The digital isolation dimming circuit for a three-phase LED tunnel lamp according to claim 1, wherein: the three-phase rectification power supply circuit comprises a power frequency transformer T1, a low-voltage rectification circuit, a low dropout linear regulator LDO circuit, an isolation DC/DC circuit 1 and an isolation DC/DC circuit 2; the power frequency transformer T1 is a transformer for converting alternating current (380V) into alternating current (5V); the low-voltage rectifying circuit comprises a rectifying bridge D1, a voltage stabilizing chip U1, a filter capacitor C1 and a filter capacitor C2; the low dropout linear regulator LDO circuit comprises a regulator chip U2, a filter capacitor C3, a filter capacitor C4, a filter capacitor C5 and a filter capacitor C6; the isolation DC/DC circuit 1 comprises a DC/DC power conversion chip U3, a filter capacitor C7 and a filter capacitor C8, and the isolation DC/DC circuit 2 comprises a DC/DC power conversion chip U4, a filter capacitor C9 and a filter capacitor C10.

3. The digital isolation dimming circuit for a three-phase LED tunnel lamp according to claim 2, wherein: the input end of the power frequency transformer T1 is connected with any two phases of an external three-phase 380V alternating current mains supply input A, B, C, the output end of the power frequency transformer T1 is connected with a pin 1 and a pin 2 of a rectifier bridge D1 respectively, a pin 3 of the rectifier bridge D1 is connected with one ends of a filter capacitor C1 and a filter capacitor C2 and is connected with a pin 1 of a voltage stabilizing chip U1, a pin 4 of the rectifier bridge D1 is used as a power ground GND, the other ends of the filter capacitor C1 and the filter capacitor C2 are connected with the power ground GND, a pin 2 of the voltage stabilizing chip U1 is connected with the power ground GND and is used as a negative end GND of a 5V power supply, and a pin 3 of the voltage stabilizing chip U1 is used as a positive end V5 of the 5V power supply and is used by the low-voltage-difference linear voltage LDO circuit, the isolation DC/DC circuit 1 and the isolation DC/DC circuit 2; pin 3 of a voltage stabilizing chip U2 is used as the input end of the low-dropout linear voltage stabilizing LDO circuit, is connected with one end of a filter capacitor C3 and a filter capacitor C4, and is connected with a positive end V5 of a 5V power supply, the other ends of the filter capacitor C3 and the filter capacitor C4 are connected with a negative end GND of the 5V power supply, and pin 2 of the voltage stabilizing chip U2 is connected with one end of the filter capacitor C5 and one end of the filter capacitor C6 and is used as a positive end V33 of a 3.3V direct-current power supply for the digital input signal conditioning circuit, the singlechip processing circuit and the dimming signal output circuit; pin 1 of the voltage stabilizing chip U2 is connected with the negative end GND of a 5V power supply and is used as the negative end GND of a 3.3V direct-current power supply; pin 2 of the DC/DC power supply conversion chip U3 is connected with one end of a filter capacitor C7 and is connected with the positive end V5 of a 5V power supply, pin 1 of the DC/DC power supply conversion chip U3 is connected with the other end of the filter capacitor C7 and is connected with the negative end GND of the 5V power supply, pin 4 of the DC/DC power supply conversion chip U3 is connected with one end of a filter capacitor C8 and is used as the positive end V5D of the 1 st path 5V direct current power supply for the digital input signal conditioning circuit, pin 3 of the DC/DC power supply conversion chip U3 is connected with the other end of the filter capacitor C8 and is used as the negative end GND1 of the 1 st path 5V direct current power supply for the digital input signal conditioning circuit; pin 2 of the DC/DC power supply conversion chip U4 is connected with one end of the filter capacitor C9 and is connected with the positive end V5 of the 5V power supply, pin 1 of the DC/DC power supply conversion chip U4 is connected with the other end of the filter capacitor C9 and is connected with the negative end GND of the 5V power supply, pin 4 of the DC/DC power supply conversion chip U4 is connected with one end of the filter capacitor C10 and is used as the positive end V5S of the 2 nd 5V direct-current power supply for the dimming signal output circuit, pin 3 of the DC/DC power supply conversion chip U4 is connected with the other end of the filter capacitor C10 and is used as the negative end GND2 of the 2 nd 5V direct-current power supply for the dimming signal output circuit.

4. The digital isolation dimming circuit for the three-phase LED tunnel lamp as claimed in any one of claims 1 to 3, wherein: the digital input signal conditioning circuit comprises a 485 serial port conversion chip U5 and an optical coupling isolation circuit.

5. The digital isolation dimming circuit for a three-phase LED tunnel lamp according to claim 4, wherein: the optical coupling isolation circuit comprises an optical coupling chip U6, an optical coupling chip U7, an optical coupling chip U8, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a bipolar transistor Q1, a bipolar transistor Q2 and a bipolar transistor Q3.

6. The digital isolation dimming circuit for a three-phase LED tunnel lamp according to claim 5, wherein: the 485 serial port conversion chip U5 is an 8-pin chip, and the optical coupler chip U6, the optical coupler chip U7 and the optical coupler chip U8 are 4-pin chips; pin 8 of the 485 serial port conversion chip U5 is connected with the positive terminal V5D of the 1 st 5V DC power supply, pin 7 of the 485 serial port conversion chip U5 is connected with one end of an external 485 serial port input signal, pin 6 of the 485 serial port conversion chip U5 is connected with the other end of the external 485 serial port input signal, pin 5 of the 485 serial port conversion chip U5 is connected with the negative terminal GND1 of the 1 st 5V DC power supply, pin 4 of the 485 serial port conversion chip U5 is connected with pin 4 of the optical coupling chip U8 and one end of a resistor R6, the other end of the resistor R6 is connected with the positive terminal V5D of the 1 st 5V DC power supply, pin 3 and pin 2 of the 485 serial port conversion chip U5 are shorted, and connected with pin 4 of the optical coupling chip U7 and one end of a resistor R9, the other end of the resistor R9 is connected with the positive terminal V5 DC 6 of the 1 st 5V DC power supply, pin 1 of the 485 serial port conversion chip U636 is connected with one end of a resistor R3, and the other end of the resistor R3 is connected with the base Q2 of the transistor, a collector of the transistor Q2 is connected with a negative end GND1 of a1 st path 5V direct current power supply, an emitter of the transistor Q2 is connected with a pin 2 of an optical coupling chip U6, a pin 1 of the optical coupling chip U6 is connected with one end of a resistor R2, the other end of the resistor R2 is connected with a positive end V5D of the 1 st path 5V direct current power supply, a pin 3 of the optical coupling chip U7 is connected with a negative end GND1 of the 1 st path 5V direct current power supply, a pin 3 of the optical coupling chip U8 is connected with a negative end GND1 of the 1 st path 5V direct current power supply, and a pin 4 of the optical coupling chip U6 is connected with one end of a resistor R1 and is used as an output RXDD of the digital input signal conditioning circuit for use of the singlechip processing circuit; the other end of the resistor R1 is connected with a 3.3V direct-current power supply positive end V33, a pin 3 of the optocoupler chip U6 is connected with a 3.3V direct-current power supply negative end GND, a pin 1 of the optocoupler chip U7 is connected with one end of the resistor R8, the other end of the resistor R8 is connected with a 3.3V direct-current power supply positive end V33, a pin 2 of the optocoupler chip U7 is connected with an emitter of the transistor Q3, a base of the transistor Q3 is connected with one end of the resistor R7, and the other end of the resistor R7 is used as an output RD of the digital input signal conditioning circuit and is used by the singlechip processing circuit; the collector of the transistor Q3 is connected with the negative end GND of the 3.3V direct current power supply; pin 1 of the optocoupler chip U8 is connected with one end of a resistor R5, the other end of the resistor R5 is connected with a 3.3V direct-current power supply positive end V33, pin 2 of the optocoupler chip U8 is connected with an emitter of a transistor Q1, a base of the transistor Q1 is connected with one end of the resistor R4, and the other end of the resistor R4 is used as an output TXD of a digital input signal conditioning circuit and is used by a singlechip processing circuit; the collector of the transistor Q1 is connected to the negative terminal GND of the 3.3V dc power supply.

7. The digital isolation dimming circuit for the three-phase LED tunnel lamp as claimed in claim 6, wherein the single chip microcomputer processing circuit comprises a single chip microcomputer MCU chip U9, a filter capacitor C11, a filter capacitor C12 and a resistor R10.

8. The digital isolation dimming circuit for the three-phase LED tunnel lamp according to claim 7, wherein the MCU chip U9 is an 8-pin MCU, pin 1 of the MCU chip U9 is connected with one end of a resistor R10, the other end of the resistor R10 is connected with a 3.3V DC power supply negative terminal GND, pin 2 of the MCU chip U9 is connected with one end of a filter capacitor C11 and a filter capacitor C12 and is connected with a 3.3V DC power supply positive terminal V33, the other ends of the filter capacitor C11 and the filter capacitor C12 are connected with a 3.3V DC power supply negative terminal GND, pin 3 of the MCU chip U9 is suspended, pin 4 of the MCU chip U9 is connected with a 3.3V DC power supply negative terminal TXGND, pin 5 of the MCU chip U9 is connected with an output terminal RXD of the digital input signal conditioning circuit as a serial communication interface RXD, pin 6 of the MCU chip U9 is connected with an output terminal of the digital input signal conditioning circuit as a serial communication interface RXD, pin 7 of the MCU chip U9 is connected to the output RD of the digital input signal conditioning circuit as the serial port communication interface RD, and pin 8 of the MCU chip U9 is used as the output PWM of the processing circuit of the MCU chip to output PWM digital signal for the light-modulating signal output circuit.

9. The digital isolation dimming circuit for the three-phase LED tunnel lamp as claimed in claim 8, wherein the dimming signal output circuit comprises an optocoupler chip U10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a filter capacitor C13 and a bipolar transistor Q4.

10. The digital isolation dimming circuit for the three-phase LED tunnel lamp according to claim 9, wherein the optical coupling chip U10 is a 4-pin linear optical coupling device, pin 1 of the optical coupling chip U10 is connected with one end of a resistor R12, the other end of the resistor R12 is connected with a positive terminal V33 of a 3.3V DC power supply, pin 2 of the optical coupling chip U10 is connected with one end of a resistor R11 and a collector of a transistor Q4, the other end of the resistor R11 is connected with one end of a filter capacitor C13 and is connected with the positive terminal V33 of the 3.3V DC power supply, the other end of the filter capacitor C13 is connected with a negative terminal GND of the 3.3V DC power supply, a base of the transistor Q4 is connected with an output end PWM of the single chip processing circuit, and an emitter of the transistor Q4 is connected with the negative terminal GND of the 3.3V DC power supply; pin 3 of opto-coupler chip U10 links to each other with the one end of resistance R14, and the output that simultaneously is as dimming signal output circuit, output PWM dimming signal supplies outside three-phase 380V's LED tunnel lamp to use, and the other end of resistance R14 links to each other with 2 nd way 5V DC power supply's negative terminal GND2, and pin 4 of opto-coupler chip U10 links to each other with the one end of resistance R13, and the other termination of resistance R13 is the positive terminal V5S of 2 nd way 5V DC power supply.

11. A dimming method using a digital isolation dimming circuit for a three-phase LED tunnel lamp according to any one of claims 1 to 10, it is characterized in that the PWM dimming signal output by the dimming signal output circuit is connected with a dimming interface of a driving chip of the AC three-phase 380V LED tunnel lamp, when the dimming is needed, the digital input signal conditioning circuit receives the 485 serial port signal input from the outside, after the 485 serial port conversion and the optical coupling isolation, output to the singlechip processing circuit, after the singlechip processing circuit processes and analyzes the received digital signal, the PWM digital signal is output to a dimming signal output circuit for use, the dimming signal output circuit outputs a dimming signal to a three-phase 380V LED tunnel lamp for use after corresponding signal processing, the output dimming signal is directly connected with a dimming interface of a driving chip of the three-phase 380V LED tunnel lamp.