CN210868221U

CN210868221U - Controller, LED lamp and LED control system through power line communication

Info

Publication number: CN210868221U
Application number: CN201921210679.1U
Authority: CN
Inventors: 甘海燕; 张红梅
Original assignee: Shenzhen Furui New Technology Co ltd
Current assignee: SHENZHEN EVERICH TECHNOLOGY CO LTD
Priority date: 2019-07-29
Filing date: 2019-07-29
Publication date: 2020-06-26
Anticipated expiration: 2029-07-29

Abstract

The utility model discloses a controller, LED lamps and lanterns and LED control system through power line communication, this controller include input protection unit, rectification and zero passage detection unit, step-down power supply unit, first MCU, the switch control unit that electricity connects in proper order, rectification and zero passage detection unit still with first MCU, switch control unit electricity are connected; the LED lamp comprises an input protection and EMC circuit, a rectification filter circuit, a high power factor voltage reduction circuit, a loop maintaining unit, an amplitude limiting detection unit, a second MCU, a chromaticity/brightness control unit and an LED lamp panel. The utility model discloses need not rewire, use original circuit change lamps and lanterns and controller can, can realize quick dimming mixing of colors and with low costs.

Description

Controller, LED lamp and LED control system through power line communication

Technical Field

The utility model relates to a LED control technology, in particular to controller, LED lamps and lanterns and LED control system through power line communication.

Background

In the field of LED dimming technology, several common application methods are currently on the market, and they have the following advantages and disadvantages:

(1) and silicon controlled phase-cut dimming: the technology has been for many years, the phase-cut dimming technology has been provided in the period of incandescent lamps, because incandescent lamps or similar lamps have resistive load characteristics, the silicon controlled dimmer realizes the dimming function by changing the voltage input to two ends of a resistive lamp through the cut wave of alternating current, after the LED lighting technology appears, the LED lamp is directly applied to the traditional silicon controlled dimmer, the problem that a plurality of silicon controlled dimms cannot be compatible occurs, and according to the characteristics of the silicon controlled dimms, when the load current flowing through the silicon controlled dimms is smaller than the control current, the silicon controlled dimms are automatically closed. When the phase-cut angle is cut to the maximum, the problems of flickering, unlightness, non-linearity of dimming and the like can occur when the voltage of the LED lamp is too low. The advantages of this technique are: the circuit does not need to be changed, and the cost is low; the disadvantages are: the device has the problems of compatibility, non-linear dimming, flicker, incapability of using full voltage, dimming and color mixing.

(2) 0-10V linear dimming: in addition to the existing wiring, the method also needs to separately wire two wires as the wires for dimming control, and a special 0-10V dimmer is used. The advantages of this technique are: the dimming effect is good, and the defects are as follows: rewiring is needed, most application scenes cannot be rewired, the reconstruction cost is extremely high, and the LED lamp is generally only provided with a dimming function.

(3) DALI/DMX 512: this method requires wiring for communication control separately in addition to the existing wiring, and is mainly used in a very small number of exclusive uses. The advantages of this technique are: the system is controlled in a centralized way, and light and color can be adjusted; the disadvantages are: the initial assembly and the transformation cost are extremely high, and the method is only applied to few professional occasions.

(4) And wireless dimming: novel LED intelligent dimming control often adopts the mode, like 433Mhz, 2.4G wireless control, Wifi, control mode such as bluetooth. The advantages of this technique are: the function expansion capability is strong, and dimming and color mixing can be realized; the disadvantages are: the wireless control distance is short, the space influence is great, the cost is high, and the problems of code falling and the like can occur in the matching and using process.

SUMMERY OF THE UTILITY MODEL

Problem to prior art existence, the utility model provides a through controller, LED lamps and lanterns and LED control system of power line communication need not rewiring, use some circuit change lamps and lanterns and controller can, can realize quick dimming, mixing of colors, switch, scintillation etc..

In order to achieve the above purpose, the specific scheme of the utility model is as follows:

a controller communicating through a power line comprises an input protection unit, a rectification and zero-crossing detection unit, a voltage reduction power supply unit, a first MCU and a switch control unit which are sequentially and electrically connected, wherein the rectification and zero-crossing detection unit is also electrically connected with the first MCU and the switch control unit; the rectification and zero-crossing detection unit comprises a first rectification circuit, the output of the first rectification circuit is divided into A, B two output ends, the A, B two output ends are respectively connected to a first MCU, the A, B two output ends output alternate sine half waves, the alternate point is a zero-crossing signal, and the first MCU is alternately triggered by the two sine half waves.

Preferably, the first rectifying circuit comprises four diodes D1-D4, anodes of the diodes D1 and D2 are grounded, cathodes of the diodes D3 and D4 are respectively connected with anodes of the diodes D3 and D4 are respectively two output ends A, B, alternating current is input from a midpoint of the diodes D1 and D3 and a midpoint of the diodes D2 and D4, and sinusoidal half waves output by the two output ends A, B are respectively generated by voltage differences between the two output ends A, B and the ground; the rectification and zero-crossing detection unit further comprises two first voltage-dividing amplitude limiting circuits, and the A, B two output ends of the first rectification circuit are connected to the first MCU through one first voltage-dividing amplitude limiting circuit respectively.

Preferably, the switch control unit comprises two MOS transistors Q1, Q2, drains of Q1 and Q2 are respectively connected to A, B two output terminals, and gates are respectively connected to the first MCU.

Preferably, the first MCU may be of the AT61F02, STM32 or STM08 family of microprocessors.

The utility model also provides a LED lamp, including loop maintenance unit, limit detection unit and the input protection and EMC unit, rectification filter unit, power factor correction control unit, second MCU and decoding unit, the LED lamp plate of electricity connection in proper order, rectification filter unit still maintains the unit through the loop and is connected with second MCU and decoding unit electricity, input protection and EMC unit still is connected with second MCU and decoding unit electricity through limit detection unit, and input voltage is stepped down to the supply voltage of second MCU and decoding unit by power factor correction control unit after the rectification, and input voltage supplies to second MCU and decoding unit after limit detection unit limit simultaneously and handles, finally realizes the regulation to the LED lamp plate, and the loop maintenance unit maintains the electric current in the circuit in the working range of the whole loop of LED lamp, limit detection unit includes two way detection circuit, the output ends of the two amplitude limiting detection circuits are electrically connected with the second MCU and the decoding unit, after the second MCU and the decoding unit are triggered, the output voltages of the two amplitude limiting detection circuits are recorded as a state I when the output voltages are high, and are recorded as a state II when the output voltages are high, and a sequence consisting of a plurality of states I and a plurality of states II is sent to the second MCU and the decoding unit for decoding processing.

Preferably, the amplitude-limiting detection unit comprises two second voltage-dividing amplitude-limiting circuits and two backward diodes D12 and D13, each second voltage-dividing amplitude-limiting circuit is electrically connected with one backward diode D12/D13, and the alternating current passes through the second voltage-dividing amplitude-limiting circuit and then is output to the second MCU through the backward diode.

Preferably, the amplitude-limiting detection unit further includes an isolation optocoupler U5, U6 or a triode Q1, Q2, the isolation optocoupler U5, U6 or a triode Q1, Q2 is connected between the backward diode D12, D13 and the second MCU, and the alternating current is sequentially input to the isolation optocoupler U5, U6 or a triode Q1, Q2 after passing through the second voltage-dividing amplitude-limiting circuit and the backward diode D12, D13, and is finally output to the second MCU.

Preferably, the loop maintaining unit comprises a MOS transistor Q5 and an isolation optocoupler U7, and the level input to U7 is reversed through U7 to control the on and off of the MOS transistor Q5.

The utility model also provides a LED control system, include as above through the controller of power line communication and as above LED lamps and lanterns, controller and LED lamps and lanterns series connection.

Adopt the technical scheme of the utility model, following beneficial effect has:

(1) the LED lamp realizes linear dimming of the LED lamp, and can realize functions of color modulation, switching, flickering and the like;

(2) the problems of poor compatibility, small dimming range, flashing and the like of the traditional phase-cut dimmer used for the LED lamp are solved;

(3) the problems of transmission distance, interference and code drop of the wireless dimming technical scheme are avoided;

(4) compared with the traditional professional dimming such as DALI and DMX512, the cost is greatly saved;

(5) wired data transmission can be realized through a power line without rewiring, and the transformation cost is reduced;

(6) the alternating current power supply is suitable for alternating current of 100V-277V and 50Hz/60Hz, and has wide application range compared with the traditional single-value alternating current power supply only suitable for 110V or 220V.

Drawings

FIG. 1 is an overall block diagram of the present invention;

FIG. 2 is a functional block diagram of a controller according to the present invention;

FIG. 3 is a circuit diagram of the controller of the present invention;

fig. 4 is a block diagram of the rectifying and zero-crossing detecting unit according to the present invention;

fig. 5 is an input/output waveform diagram of the first rectifying circuit of the present invention;

fig. 6 is a waveform diagram of the first rectifying circuit A, B two points and the switch control units Q1 and Q2;

fig. 7(a) is a first input/output waveform diagram of the first MCU of the present invention;

fig. 7(b) is a second input/output waveform diagram of the first MCU of the present invention;

fig. 8 is a functional block diagram of the LED lamp of the present invention;

fig. 9(a) is a first circuit diagram embodiment of the amplitude limiting and detecting unit of the LED lamp according to the present invention;

fig. 9(b) is a second circuit diagram of the amplitude limiting and detecting unit of the LED lamp according to the present invention;

fig. 9(c) is a third circuit diagram of the amplitude limiting and detecting unit of the LED lamp according to the present invention;

fig. 10 is a waveform diagram of the output of the amplitude limiting detection unit according to the present invention;

fig. 11 is a circuit diagram of the loop maintaining unit of the LED lamp of the present invention;

fig. 12 is a schematic diagram of the operation principle of the loop maintaining unit according to the present invention.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1, the utility model provides a drive-by-wire of LED lamp mixing of colors system of adjusting luminance, the drive-by-wire including the LED lamp is adjusted luminance mixing of colors controller and LED lamps and lanterns, controller and lamps and lanterns series connection.

Referring to fig. 2, the utility model provides a controller through power line communication, including input protection unit, rectification and zero cross detection unit, step-down power supply unit, first MCU, the switch control unit that electricity connects in proper order, rectification and zero cross detection unit still with first MCU, switch control unit electricity is connected; the rectification and zero-crossing detection unit comprises a first rectification circuit, the output of the first rectification circuit is divided into A, B two output ends (hereinafter referred to as point A and point B), the A, B two output ends are respectively connected to a first MCU, the A, B two output ends output alternate sine half waves, the alternate points are zero-crossing signals, and the first MCU is triggered by the two sine half waves alternately.

Referring to fig. 3 to 5, the first rectifying circuit includes four diodes D1-D4, anodes of the diodes D1 and D2 are grounded, cathodes of the diodes D3 and D4 are connected to anodes of the diodes D3 and D4, cathodes of the diodes D3 and D4 are A, B output ends, alternating current is input from a midpoint of the diodes D1 and D3 and a midpoint of the diodes D2 and D4, sinusoidal half-waves output from two points A, B are generated by a voltage difference between the two points A, B and the ground end, when a sinusoidal wave passes through the first rectifying circuit, a point a outputs a positive half cycle, B point B outputs a negative half cycle, and a zero-crossing signal is generated when waveforms of the positive and the negative half cycles alternate.

The rectification and zero-crossing detection unit further comprises two first voltage-dividing amplitude limiting circuits, wherein A, B two output ends of the first rectification circuit are respectively connected to the first MCU through one first voltage-dividing amplitude limiting circuit, and the input and output waveforms of the first rectification circuit are shown in fig. 5.

The circuit design of the rectification and zero-crossing detection unit realizes the rectification function on one hand, and on the other hand, the zero-crossing signal is generated alternately through the waveforms of A, B two points, so that the circuit is greatly simplified, and the reconstruction cost is reduced.

With continued reference to fig. 3, the switching control unit includes two MOS transistors Q1, Q2, wherein the drains of Q1 and Q2 are respectively connected to A, B two output terminals, and the gates are respectively connected to the first MCU.

In this embodiment, the first MCU is of a model AT61F 02.

The working principle of the controller is as follows:

referring to fig. 1 to 2, the controller and all the LED lamps are connected in series, an ac input voltage is simultaneously input to two connection terminals (i.e., an input terminal and an output terminal in fig. 2) of the controller, a 100V-277V voltage is connected to the input protection unit, the circuit has an overcurrent and overtemperature protection function, and the voltage is connected to the rectification and zero-crossing detection unit after passing through the input protection unit.

Referring to fig. 2 to 3, the input alternating current forms two alternate sinusoidal half waves after being rectified by the rectification and zero-crossing detection unit, wherein one sinusoidal half wave is stepped down to a suitable working voltage of the first MCU by the step-down power supply unit, and the two alternate sinusoidal half waves are simultaneously transmitted to the first MCU, and the first MCU is triggered by the two alternate sinusoidal half waves and then outputs a control voltage to the switching control unit.

Referring to fig. 3 to 5, a first rectifying circuit in the rectifying and zero-crossing detecting unit is different from a conventional rectifying bridge in that two forward output terminals are not connected together but are separated into A, B two points, so that an input sinusoidal alternating-current voltage is rectified into A, B two alternating sinusoidal half-waves respectively, the input and output waveforms of the first rectifying circuit are as shown in fig. 5, the two sinusoidal half-waves alternately trigger the first MCU, and a zero-crossing signal generated alternately is fed back to the first MCU.

With continued reference to fig. 3 and 6, when Q1 and Q2 are turned off, the voltage waveforms at points a and B are alternating sinusoidal half waves, and both CTL-a and CTL-B output pins of the first MCU output low.

Continuing to refer to fig. 3 and fig. 7(a), after the output voltages at the output end point a and the output end point B of the first rectification circuit are subjected to voltage division and amplitude limitation, the output voltages are transmitted to two pins INT-a and INT-B of the first MCU, at this time, the waveforms of INT-a and INT-B are only a part of a positive half cycle, because the voltages of INT-a and INT-B are alternately input, in the same cycle of the alternating current, in the positive half cycle, after the first MCU receives the information that INT-a is at a high level, CTL-a outputs a high level after a delay time t, Q1 is turned on, and CTL-B outputs a low level, Q2 is turned off, in the negative half cycle, after the first MCU receives the information that INT-B is at a high level, CTL-B outputs a high level after a delay time t time, CTL 2 is turned on, and at the same time, CTL-a outputs a low level, and Q1 is turned.

Referring to fig. 7(B), by changing the delay time t, the waveform of CTL-A, CTL-B can be changed to change the on-time of Q1 and Q2 in the switch control unit, taking t1> t2 as an example of times t1 and t 2.

Referring to fig. 8, an LED lamp includes a loop maintaining unit, a limiting detection unit, and an input protection and EMC unit, a rectifying filter unit, a power factor correction control unit, a second MCU and a decoding unit, which are electrically connected in sequence, the rectifying filter unit is further electrically connected with the second MCU and the decoding unit through the loop maintaining unit, the input protection and EMC unit is further electrically connected with the second MCU and the decoding unit through the limiting detection unit, an input voltage is rectified and then reduced to a supply voltage of the second MCU and the decoding unit by the power factor correction control unit, and the input voltage is limited by the limiting detection unit and then supplied to the second MCU and the decoding unit for processing, so as to finally realize adjustment of the LED lamp panel, and the loop maintaining unit maintains a current in the circuit within a working range of the entire loop of the LED lamp, the amplitude limiting detection unit comprises two amplitude limiting detection circuits, the output ends of the two amplitude limiting detection circuits are electrically connected with the second MCU and the decoding unit, after the second MCU and the decoding unit are triggered, in a limited time, the output voltages of the two amplitude limiting detection circuits are recorded as a state I when the output voltages are high, and are recorded as a state II when the output voltages are high, and a sequence consisting of a plurality of states I and a plurality of states II is sent to the second MCU and the decoding unit for decoding.

Referring to fig. 9(a), the amplitude-limiting detection unit adopts a non-isolation architecture, and includes two second voltage-dividing amplitude-limiting circuits and two backward diodes D12, D13, each of the second voltage-dividing amplitude-limiting circuits is electrically connected to one of the backward diodes D12/D13, and the alternating current passes through the second voltage-dividing amplitude-limiting circuits and then is output to the second MCU and the decoding unit through the backward diodes;

referring to fig. 9(b), the amplitude-limiting detection unit adopts an isolation architecture, and is additionally provided with triodes Q1 and Q2 on the basis of the isolation architecture shown in fig. 9(a), wherein the triodes Q1 and Q2 are connected between the backward diodes D12 and D13 and the second MCU and the decoding unit, and alternating current sequentially passes through the second voltage-dividing amplitude-limiting circuit and the backward diodes D12 and D13, is input to the triodes Q1 and Q2, and is finally output to the second MCU and the decoding unit;

referring to fig. 9(c), the amplitude-limiting detection unit adopts an isolation architecture, isolation optocouplers U5 and U6 are added on the basis of the cost isolation architecture shown in fig. 9(a), the isolation optocouplers U5 and U6 are connected between the backward diodes D12 and D13 and the second MCU and the decoding unit, and the alternating current sequentially passes through the second voltage-dividing amplitude-limiting circuit and the backward diodes D12 and D13, is input to the anode of the isolation optocoupler U5/U6, and is finally output to the second MCU and the decoding unit;

note that, when the circuit shown in fig. 9(a) is used as the slice detection unit, the input signal does not need to be inverted, and when the circuit shown in fig. 9(b) or fig. 9(c) is used, the input signal needs to be inverted once, and the output waveform of the slice detection unit is as shown in fig. 10.

Referring to fig. 11, the loop maintaining unit includes a MOS transistor Q5 and an isolation optocoupler U7, and the level input to U7 is reversed by U7 to control the on and off of the MOS transistor Q5.

The working principle of the LED lamp is as follows:

referring to fig. 8, after the alternating voltage is input from the input protection and EMC circuit, the alternating voltage sequentially passes through the rectification filter unit and the power factor correction control unit to perform energy conversion, and then outputs a direct current voltage, and meanwhile, the two input alternating voltages pass through the amplitude limiting detection unit, are subjected to voltage division and amplitude limitation, are connected to the second MCU and the decoding unit to perform signal decoding, and control the LED lamp panel according to the decoded data.

Referring to fig. 9(C), the amplitude-limiting detection unit is connected to the ac, after voltage limiting by the second voltage-dividing amplitude-limiting circuit composed of R21, R34, C15, R22, R35, and C14, is connected to the anodes of the isolation optocouplers U5 and U6 by R36 and R37, and after isolation coupling and inversion, is connected to the second MCU and the decoding unit by the ports PA0 and PA1 for decoding processing and chrominance/luminance control.

As can be seen from fig. 6 and fig. 7(a) and 7(B), the pulse width of INT-a and INT-B can be changed by changing the delay time t, and referring to fig. 9(c) and fig. 10, taking delay times t1 and t2 as mutexamples, t1> t2 is taken, the second MCU and the decoding unit receives the voltages on PA0 and PA1, generates an internal interrupt signal when PA1 detects the mutexternal voltage inversion, the second MCU and the decoding unit prohibits the mutexternal interrupt from judging the levels of PA0 and PA1 at any time mutexceeding t2 but less than t1, and the pulse width of the negative half-cycle waveform is fixed, so that it is taken as a reference signal or a clock signal; in a time period exceeding t2 but less than t1, when the levels of the PA0 and the PA1 are both high, the digital circuit is judged to be in one state (for example, judged to be 0), otherwise, the digital circuit is judged to be in the other state (for example, judged to be 1, 0 and 1 are opposite, and only two different states are distinguished here), and the second MCU and the decoding unit decodes the sequence of 0 and 1 and outputs a corresponding LED control signal.

Adopt PA0 and PA1 to judge 0 and 1 in the digital circuit for the mode of high level simultaneously, and do not adopt the pulse width to judge 0 and 1 effectual solved the problem that power input distinguishes zero live wire, avoided the transmission distance of wireless dimming technical scheme, disturb and fall the problem of sign indicating number moreover, also need not rewiring in the practical application, just can realize wired data transmission through the power line, greatly reduced the transformation cost.

Referring to fig. 1, 2 and 8, since the step-down power supply unit reduces the operating voltage of the controller, when the brightness of the LED lamp is reduced, the current flowing through the controller and the LED lamp also becomes smaller, and when the current is reduced to a certain degree, the power supply requirement of the controller cannot be met, and the controller is turned off due to too small current, and cannot work normally; referring to fig. 11 and 12, in a time period when the controller is turned off, in order to reduce the system power, the low level output by U2 is reversed by the optocoupler U7 to turn on the MOS transistor Q5, so that the resistor R58 is connected to the loop circuit to turn on the whole circuit, thereby achieving the purpose of maintaining the power supply of the controller; meanwhile, in order to reduce useless loss, the loop maintaining unit works only when the system power is lower than 50% so as to reduce the loss of the loop.

The loop maintaining unit maintains the current of the whole loop in a normal working state, further increases the dimming range and reduces flicker.

The input protection unit, the step-down power supply unit, the first MCU in the controller, the input protection and EMC unit, the rectification filter unit, the power factor correction control unit, the second MCU and the decoding unit in the LED lamp and the LED lamp panel are all conventional technologies in the field, and details are not repeated here.

It should be noted that although the voltage-reducing power supply unit in the controller is a conventional technology in the art, the present invention adopts a voltage-reducing circuit suitable for 100V-277V and 50Hz/60Hz ac, and compared with the conventional single-value ac only suitable for 110V or 220V, the present invention has a wide application range.

The above only is the preferred embodiment of the present invention, not so limiting the patent scope of the present invention, all of which are in the utility model discloses a conceive, utilize the equivalent structure transform that the content of the specification and the attached drawings did, or directly/indirectly use all to include in other relevant technical fields the protection scope of the present invention.

Claims

1. A controller communicating through a power line comprises an input protection unit, a rectification and zero-crossing detection unit, a voltage reduction power supply unit, a first MCU and a switch control unit which are sequentially and electrically connected, wherein the rectification and zero-crossing detection unit is also electrically connected with the first MCU and the switch control unit; the rectifying and zero-crossing detecting unit is characterized by comprising a first rectifying circuit, the output of the first rectifying circuit is divided into A, B two output ends, A, B two output ends are respectively connected to a first MCU, A, B two output ends output alternate sine half waves, the alternate point is a zero-crossing signal, and the first MCU is alternately triggered by the two sine half waves.

2. The controller according to claim 1, wherein the first rectifying circuit comprises four diodes D1-D4, the anodes of the diodes D1 and D2 are grounded, the cathodes of the diodes D3 and D4 are connected to the anodes of the diodes D3 and D4, the cathodes of the diodes D3 and D4 are A, B outputs, respectively, ac power is input from the midpoint of the diodes D1 and D3 and the midpoint of the diodes D2 and D4, and half-wave sine output from the two outputs of A, B is generated by the voltage difference between the two outputs of A, B and the ground; the rectification and zero-crossing detection unit further comprises two first voltage-dividing amplitude limiting circuits, and the A, B two output ends of the first rectification circuit are connected to the first MCU through one first voltage-dividing amplitude limiting circuit respectively.

3. The controller according to claim 2, wherein the switching control unit comprises two MOS transistors Q1, Q2, the drains of Q1 and Q2 are connected to A, B two output terminals, and the gates are connected to the first MCU.

4. An LED lamp comprises a loop maintaining unit, an amplitude limiting detection unit, an input protection and EMC unit, a rectifying and filtering unit, a power factor correction control unit, a second MCU and decoding unit and an LED lamp panel which are electrically connected in sequence, wherein the rectifying and filtering unit is electrically connected with the second MCU and the decoding unit through the loop maintaining unit, the input protection and EMC unit is electrically connected with the second MCU and the decoding unit through the amplitude limiting detection unit, input voltage is rectified and then is reduced to supply voltage of the second MCU and the decoding unit by the power factor correction control unit, meanwhile, the input voltage is supplied to the second MCU and the decoding unit for processing after being subjected to amplitude limiting by the amplitude limiting detection unit, finally, the regulation of the LED lamp panel is realized, and meanwhile, the loop maintaining unit maintains current in a circuit in the working range of the whole loop of the LED lamp, the output ends of the two amplitude limiting detection circuits are electrically connected with the second MCU and the decoding unit, after the second MCU and the decoding unit are triggered, the output voltages of the two amplitude limiting detection circuits are recorded as a state I when the output voltages are high, and are recorded as a state II when the output voltages are high, and a sequence consisting of a plurality of states I and a plurality of states II is sent to the second MCU and the decoding unit for decoding processing.

5. The LED lamp as claimed in claim 4, wherein the amplitude-limiting detection unit comprises two second voltage-dividing amplitude-limiting circuits and two backward diodes D12, D13, each of the second voltage-dividing amplitude-limiting circuits is electrically connected to one of the backward diodes D12/D13, and the AC current passes through the second voltage-dividing amplitude-limiting circuits and then passes through the backward diodes to be output to the second MCU.

6. The LED lamp as claimed in claim 5, wherein the amplitude-limiting detection unit further comprises an isolation optocoupler U5, U6 or a triode Q1, Q2, the isolation optocoupler U5, U6 or a triode Q1, Q2 are connected between a backward diode D12, D13 and the second MCU, and the alternating current is sequentially passed through a second voltage-dividing amplitude-limiting circuit and the backward diode D12, D13, then input to the isolation optocoupler U5, U6 or a triode Q1, Q2, and finally output to the second MCU.

7. The LED lamp as claimed in claim 5 or 6, wherein the loop maintaining unit comprises a MOS transistor Q5 and an isolation optocoupler U7, and the input level to U7 controls the MOS transistor Q5 to be turned on and off after being inverted by U7.

8. An LED control system comprising the controller for communication over power lines of any one of claims 1 to 3 and the LED lamp of any one of claims 4 to 7, the controller and the LED lamp being connected in series.