WO2022188244A1

WO2022188244A1 - Led driving circuit and led straight-tube lamp

Info

Publication number: WO2022188244A1
Application number: PCT/CN2021/088545
Authority: WO
Inventors: 周家明; 蒲纪忠; 甘彩英; 赵艺佼
Original assignee: 晨辉光宝科技股份有限公司
Priority date: 2021-03-10
Filing date: 2021-04-20
Publication date: 2022-09-15
Also published as: CN113056057A

Abstract

An LED driving circuit and an LED straight-tube lamp. The LED driving circuit comprises: a first alternating-current input end and a second alternating-current input end, which are used for receiving alternating-current signals input from the outside; a first rectifier circuit and a second rectifier circuit, which are used for rectifying the input alternating-current signals to obtain rectified signals; a third rectifier circuit, which is coupled to the first alternating-current input end by means of a first switching unit, and is coupled to the second alternating-current input end by means of a second switching unit, wherein when the input alternating-current signals are low-frequency signals, the switching units are turned off, and when the input alternating-current signals are high-frequency signals, the switching units are turned on, and the alternating current signals are rectified by the third rectifier circuit, and then supply power to an LED; a filtering circuit, which is coupled to the first rectifier circuit and the second rectifier circuit and filters the rectified signals to obtain filtered signals; and a constant-current circuit, which is coupled to the filtering circuit, receives the filtered signals and supplies power to the LED. By means of the present application, an existing TYPE A+B driving circuit structure is simplified, and costs are reduced.

Description

LED driver circuit and LED straight tube light

technical field

The invention relates to the technical field of LED lighting, in particular to an LED driving circuit and an LED straight tube lamp.

Background technique

LED lamps have the advantages of energy saving, environmental protection and long life. With the development of LED technology, they are gradually replacing traditional incandescent lamps and fluorescent lamps. Traditional fluorescent lamps generally include electronic ballasts, fluorescent lamps, and lamp carriers. In order to save energy and protect the environment, it is necessary to replace traditional fluorescent lamps with LED lamps.

There are two solutions to replace the existing fluorescent lamps: the first is to replace the lamps directly without modifying the lamps, that is, to directly remove the fluorescent lamps and replace them with LED lamps; the second is to bypass the electronic ballast by cutting the wire. , realize single-ended or double-ended power feeding through wiring.

Therefore, there are mainly three types of LED lamp products on the market: TYPE A replacement type; TYPE B trimming type; TYPE A+B dual-function conversion compatible type. Among them, the existing TYPE The A+B type driving circuit is relatively complex, with many components and high manufacturing cost.

technical problem

The invention provides an LED driving circuit and an LED straight tube lamp, and solves the problems of complex structure and high cost of the existing TYPE A+B driving circuit.

technical solutions

LED driver circuit, including:

The first AC input terminal and the second AC input terminal receive externally input AC signals;

The first rectifier circuit and the second rectifier circuit are respectively coupled to the first AC input terminal and the second AC input terminal, and rectify the input AC signal to obtain a rectified signal;

A third rectifier circuit, which is coupled to the first AC input terminal through a first switching unit, and is coupled to the second AC input terminal through a second switching unit; when the input AC signal is a low-frequency signal, the switching unit is turned off ; When the input AC signal is a high-frequency signal, the switching unit is turned on, and the AC signal is rectified by the third rectifier circuit to supply power to the LED;

a filter circuit, which is coupled to the first rectifier circuit and the second rectifier circuit, and filters the rectified signal to obtain the filtered signal;

A constant current circuit, which is coupled to the filter circuit, receives the filtered signal, and supplies power to the LED.

Several optional methods are also provided below, which are not intended to be additional limitations on the above-mentioned overall solution, but are merely further additions or optimizations. On the premise of no technical or logical contradiction, each optional method can be independently implemented for the above-mentioned overall solution. The combination can also be a combination between multiple optional ways.

Optionally, the first switching unit and the second switching unit allow high-frequency signals to pass through, and block low-frequency signals from passing through.

Optionally, the first switching unit and the second switching unit are first capacitors.

Optionally, the capacitance value of the first capacitor ranges from 10 NF to 68 NF.

Optionally, a spike absorption unit is coupled between the first AC input end and the second AC input end.

Optionally, the spike absorption unit is a second capacitor.

Optionally, the capacitance value of the second capacitor is 0.47 NF to 3.3 NF.

Optionally, a leakage protection circuit is provided between the first rectifier circuit and the filter circuit.

Optionally, a voltage detection unit is coupled between the two output ends of the second rectifier circuit, and an abnormality protection unit is coupled between the second AC input end and the second rectifier circuit. When the unit detects an abnormal voltage, the abnormal protection unit will disconnect the power supply circuit.

Optionally, the voltage detection unit is a varistor, and the abnormality protection unit is a thermal fuse adjacent to the varistor.

The invention also provides an LED straight tube lamp, comprising a lamp tube, end caps arranged at both ends of the lamp tube and the LED driving circuit, each end cap is provided with two pins, one of which is on the end cap The pin of the first AC input terminal is coupled to the other end cover, and the pin of the other end cap is coupled to the second AC input terminal and is short-circuited.

beneficial effect

By arranging the first switching unit and the second switching unit, the present invention can automatically detect the commercial power or electronic ballast, so that the lamp can work normally under the low frequency signal or the high frequency signal, and the present invention simplifies the existing TYPE A+ The B-type drive circuit structure reduces the manufacturing cost.

Description of drawings

1 is a schematic diagram of a module structure of an LED drive circuit of the present invention;

2 is a schematic diagram of a filter circuit in the LED drive circuit of the present invention;

3 is a schematic diagram of a constant current circuit in the LED drive circuit of the present invention;

4 is a schematic diagram of a leakage protection circuit in the LED drive circuit of the present invention;

5 is a schematic diagram of an LED driving circuit of the present invention;

FIG. 6 is a schematic structural diagram of the LED straight tube lamp of the present invention.

The reference numerals in the figure are explained as follows:

1. LED straight tube light;

10. Lamp tube;

20, end cap; 21, pin;

30, drive circuit; 31, first rectifier circuit; 32, second rectifier circuit; 33, third rectifier circuit; 34, leakage protection circuit; 35, filter circuit; 36, constant current circuit; 37, first AC input terminal 38, the second AC input; 39, the DC output; 40, the peak absorption unit; 41, the first switching unit; 42, the second switching unit.

Embodiments of the present invention

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that when a component is referred to as being "connected" to another component, it can be directly connected to the other component or an intervening component may also exist. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a co-existing centered component.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Due to the complex structure of the existing TypeA+B drive circuit, in order to simplify the circuit structure, as shown in FIG. 1, the present invention provides an LED drive circuit 30, which includes a first AC input end 37, a second AC input end 38, a A rectifier circuit 31 , a second rectifier circuit 32 , a third rectifier circuit 33 , a filter circuit 35 and a constant current circuit 36 .

Among them, the first AC input terminal 37 and the second AC input terminal 38 are used to receive externally input AC signals, and are energy input ports, which generally have a neutral port and a live wire port, and of course may only have a neutral wire port or a live wire port.

The first rectifier circuit 31 and the second rectifier circuit 32 are respectively coupled to the first AC input terminal 37 and the second AC input terminal 38 to rectify the input AC signal, convert the AC signal into a DC signal, and obtain a rectified signal.

The third rectifier circuit 33 is coupled to the first AC input terminal 37 through the first switching unit 41, and is coupled to the second AC input terminal 38 through the second switching unit 42; when the input AC signal is a low-frequency signal, the switching unit is turned off; When the input AC signal is a high-frequency signal, the switching unit is turned on, and the AC signal is rectified by the third rectifier circuit 33 to supply power to the LED;

The signal rectified by the first rectifier circuit 31 and the second rectifier circuit 32 has relatively large noise and generally needs to be filtered. The filter circuit 35 is coupled to the first rectifier circuit 31 and the second rectifier circuit 32 to filter the rectified signal. The filtered signal is obtained, so that the output signal is smoother.

The filtered signal is still not smooth enough. In order to output a more stable current to the LED, the constant current circuit 36 is coupled to the filter circuit 35, receives the filtered signal, and supplies power to the LED after processing.

The rectifier circuit, the filter circuit 35 and the constant current circuit 36 of the present invention can all adopt the prior art. In order to better understand the present invention, as shown in FIGS. 2 to 5 , each circuit is introduced below.

The rectifier circuit used in the present invention adopts a bridge rectifier circuit commonly used in the art. Two of the input terminals of the first rectifier circuit 31 are respectively coupled to the L terminal and the NI terminal of the first AC input terminal 37. Among the two output terminals, one output terminal is coupled to the input terminal of the filter circuit 35, and the other output terminal is connected to the input terminal of the filter circuit 35. coupled to the first ground wire.

Two of the input terminals of the second rectifier circuit 32 are respectively coupled to the AC2 terminal and the AC3 terminal of the second AC input terminal 38 . Among the other two output terminals, one of the output terminals is coupled to the input terminal of the filter circuit 35 , and the other output terminal is coupled to the input terminal of the filter circuit 35 . The terminal is coupled to the first ground wire.

Two of the input terminals of the third rectifier circuit 33 are respectively coupled to the first switching unit 41 and the second switching unit 42 , and the other two output terminals are respectively coupled to the DC output terminal 39 . A zener diode TVS3 is coupled between the two output ends of the third rectifier circuit 33 .

The so-called first switching unit 41 and second switching unit 42 refer to electronic components or circuits composed of electronic components that allow high-frequency signals to pass through and block low-frequency signals to pass through. The two switching units 42 are a capacitor C7 and a capacitor C8 respectively, and their capacitance values are 10NF to 68 NF, and a typical value is 22 NF.

In order to ensure the safety of the circuit during actual use, fuses are installed on each port of the first AC input end 37 and the second AC input end 38, respectively fuse FXA, fuse FXB, fuse FXC, and fuse FXD. The fuse FXA at the L end of the input end 37 is also coupled to a fuse F1, and the fuse F1 is coupled to the first rectifier circuit 31; the fuse FXD and the fuse FXC of the second AC input end 38 are connected in parallel with a resistor RX1 and a capacitor CX1, and The fuse FXD is coupled to a fuse FX2, and the fuse FX2 is coupled to two input terminals of the second rectifier circuit 32, and one of the input terminals is connected to the second switching unit 42, that is, the capacitor C8. A sixth capacitor C6 is disposed between two input ends of the first rectifier circuit 31 , and the fuse FXB is coupled to the first switching unit 41 , that is, the capacitor C7 .

As shown in FIG. 2 , the filter circuit 35 includes a capacitor C1, a capacitor C2, a first inductor L1, a second inductor L2, a tenth resistor R10 and a seventh resistor R7. The capacitor C1 is coupled between the output end of the first rectifier circuit 31 and the first ground wire, and the capacitor C2 is coupled between the output end of the filter circuit 35 and the second ground wire. The first inductor L1 and the tenth resistor R10 are coupled in parallel, and one end of the first inductor L1 is coupled to the first ground wire, the other end of the first inductor L1 is coupled to the second ground wire, and the second inductor L2 is connected to the first ground wire. Seven resistors R7 are coupled in parallel, one end of the second inductor L2 is coupled to the output end of the first rectifier circuit 31 , and the other end of the second inductor L2 is coupled to the output end of the filter circuit 35 .

As shown in FIG. 3 , the input terminal of the constant current circuit 36 is coupled to the output terminal of the filter circuit 35 , and the output terminal of the constant current circuit 36 is respectively coupled to the V1+ terminal of the DC power output terminal 39 and the V1- terminal of the DC power output terminal 39 . catch.

The constant current circuit 36 is used to convert the input DC voltage into another DC voltage or voltages. In this embodiment, the constant current circuit 36 includes a first control chip U1 and a transformer T1. One end of the primary coil of the transformer T1 is coupled to the output end of the filter circuit 35 through the third diode D3, and the other end of the primary coil is connected to the first end of the filter circuit 35. The five diodes D5 are coupled to the V1- terminal of the DC power output terminal 39, and are coupled to the V1+ terminal of the DC power output terminal 39 together with the first electrolytic capacitor CD1. A fourteenth resistor R14 is arranged between the V1- terminal of the DC power output terminal 39 and the V1+ terminal of the DC power output terminal 39, and the fourteenth resistor R14 is coupled to the second ground wire through the capacitor C9. A second electrolytic capacitor CD2 connected in parallel with the fifth diode D5 is also provided on the V1-terminal.

The input end of the constant current circuit 36 is sequentially coupled to the eighth resistor R8, the ninth resistor R9 and the VCC end of the first control chip U1, wherein one end of the primary coil of the transformer T1 is coupled to the second diode D2 sequentially. . The eleventh resistor R11 is coupled with the ninth resistor R9, and the ninth resistor R9 and the second ground wire are coupled with a capacitor C4. The second ground wire is also coupled to the FB terminal of the first control chip U1 through the thirteenth resistor R13 and the capacitor C3 in parallel, and the twelfth resistor R12 connected in series to one end of the primary coil, respectively.

In addition, the COM terminal of the first control chip U1 is coupled to the capacitor C5, and the SNP terminal is coupled to the second ground wire through the resistor RS1 and the resistor RS2 connected in series.

The first control chip U1 is used to control the magnitude of the output voltage of the constant current circuit 36 . Specifically, the first control chip U1 can use a PWM control chip. Due to the energy storage function of the transformer T1, the node voltage inside the first control chip U1 will slowly rise. Voltage comparison, when the reference voltage is reached, the first control chip U1 sends a PWM signal internally, so that the switch between the drain terminal Drain and the ground terminal GND is disconnected, and the anode between the anode of the third diode D3 and the second ground wire is disconnected. When the connection is disconnected, due to the energy storage effect of the transformer T1, it will continue to discharge the load through the third diode D3. When the resistance division voltage inside the first control chip U1 is 0, one working cycle inside the first control chip U1 ends, and the next cycle starts. Since the transformer T1 has the function of changing the resistance value of the current, if the switching frequency of the switching tube of the first control chip U1 is large enough, such as 50K-80K, the current can be made stable enough, so that the LED tube 10 has no flicker.

When the ballast starts to work, it outputs high-frequency high-voltage 50~80KHz, 800~1200V, the first AC input terminal 37 and the second AC input terminal 38 receive the high-frequency AC signal. At this time, the first switching unit 41 is the capacitor C7 and the The second switching unit 42, that is, the capacitor C8, is turned on, and the high-frequency AC signal passes through the third rectifier circuit 33 and then is filtered by the first electrolytic capacitor CD1 and the second electrolytic capacitor CD2 to supply power to the LED normally.

When connected to the mains, the low-frequency low-voltage output is 50~60Hz, 120~277V, and the present invention can adopt single-ended power feeding or double-ended power feeding. When single-ended power supply is used, the port of the first AC input terminal 37 or the second AC input terminal 38 can be arbitrarily selected to receive the low-frequency AC signal. The AC signal passes through the first rectifier circuit 31 or the second rectifier circuit 32, and then passes through the filter circuit. 35 and constant current circuit 36. At this time, the first control chip U1 is working, and the electrolytic capacitor CD1 is discharged. Since the frequency of the high-frequency switching circuit is high enough, the voltage and current loaded at both ends of the load can be kept stable; , select the live wire of one port of the first AC input terminal 37 and the second AC input terminal 38 and the neutral wire of the other port. At this time, the AC signal passes through the rectifier circuit adjacent to the above live wire (the first rectifier circuit 31 or The second rectifier circuit 32), and then normally supply power to the LED through the same filter circuit 35 and constant current circuit 36 as the single-ended power supply.

In one embodiment, in order to protect the circuit, a spike absorption unit 40 is coupled between the first AC input terminal 37 and the second AC input terminal 38 and is located between the fuse FXB and the two input terminals of the second rectifier circuit 32 . Wherein, the peak absorption unit 40 is the second capacitor CX2, and its capacitance value is 0.47NF~3.3NF, and the typical value is 1NF.

In one embodiment, in order to ensure the safety of electricity consumption, a leakage protection circuit 34 is provided between the first rectifier circuit 31 and the filter circuit 35 . As shown in FIG. 4 , the output end of the first rectifier circuit 31 is sequentially coupled to the third resistor R3, the fourth resistor R4, the fifth resistor R5, the capacitor C1 and the VCC terminal of the second control chip U2, wherein the fourth resistor R4 The connection with the fifth resistor R5 is coupled to the DET terminal of the second control chip U2, the connection between the fifth resistor R5 and the capacitor C1 is coupled to the GND terminal of the second control chip, and the capacitor C2 and the first ground line are connected in parallel with each other. The fifteenth resistor R15. The DRAIN terminal of the second control chip U2 is coupled to the first ground line by coupling the voltage regulator tube TVS1 and the VS terminal together. Wherein, for safety consideration, a bidirectional breakdown diode D10 is coupled between the DRAIN terminal of the second control chip U2 and the first ground wire, and its breakdown voltage is 400V.

The leakage protection circuit 34 further includes a first resistor R1, a second resistor R2 and the REC terminal of the second control chip U2 sequentially coupled to the output terminal of the first rectifier circuit 31, and the output terminal of the first rectifier circuit 31 and the filter circuit 35. The first diode D1 is coupled between the input terminals.

In one embodiment, in order to further protect the overall circuit, a voltage detection unit is coupled between the two output ends of the second rectifier circuit 32 , and an abnormality protection is coupled between the second AC input end 38 and the second rectifier circuit 32 . unit, when the voltage detection unit detects that the voltage is abnormal, the abnormality protection unit disconnects the power supply circuit. The voltage detection unit is a varistor RV1, and the abnormal protection unit is a thermal fuse F3 adjacent to the varistor RV1.

In one embodiment, the present invention further includes an LED straight tube lamp 1, as shown in FIG. 6, comprising a lamp tube 10, end caps 20 disposed at both ends of the lamp tube 10, and an LED driving circuit 30, each end cap 20 There are two pins 21 on both, one of the pins 21 on the end cover 20 is coupled with the first AC input terminal 37, and the pins 21 on the other end cover 20 are coupled with the second AC input terminal 38, and for shorting.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification. When the technical features of different embodiments are embodied in the same drawing, it can be considered that the drawing also discloses the combination examples of the various embodiments involved.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the patent application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention.

Claims

The LED drive circuit is characterized in that it includes:

The first AC input terminal and the second AC input terminal receive externally input AC signals;

The first rectifier circuit and the second rectifier circuit are respectively coupled to the first AC input terminal and the second AC input terminal, and rectify the input AC signal to obtain a rectified signal;

A third rectifier circuit, which is coupled to the first AC input terminal through a first switching unit, and is coupled to the second AC input terminal through a second switching unit; when the input AC signal is a low-frequency signal, the switching unit is turned off ; When the input AC signal is a high-frequency signal, the switching unit is turned on, and the AC signal is rectified by the third rectifier circuit to supply power to the LED;

a filter circuit, which is coupled to the first rectifier circuit and the second rectifier circuit, and filters the rectified signal to obtain the filtered signal;

A constant current circuit, which is coupled to the filter circuit, receives the filtered signal, and supplies power to the LED.
The LED driving circuit according to claim 1, wherein the first switching unit and the second switching unit allow high-frequency signals to pass through and block low-frequency signals from passing through.
The LED driving circuit according to claim 2, wherein the first switching unit and the second switching unit are first capacitors.
The LED driving circuit according to claim 3, wherein the capacitance value of the first capacitor is 10NF˜68 nf.
The LED driving circuit according to claim 1, wherein a spike absorption unit is coupled between the first AC input terminal and the second AC input terminal.
The LED driving circuit according to claim 5, wherein the peak absorption unit is a second capacitor.
The LED driving circuit according to claim 6, wherein the capacitance value of the second capacitor is 0.47NF~3.3 nf.
The LED driving circuit according to claim 1, wherein a leakage protection circuit is arranged between the first rectifier circuit and the filter circuit.
The LED driving circuit according to claim 1, wherein a voltage detection unit is coupled between two output ends of the second rectifier circuit, and a voltage detection unit is coupled between the second AC input end and the second rectifier circuit An abnormality protection unit is connected, and when the voltage detection unit detects that the voltage is abnormal, the abnormality protection unit disconnects the power supply circuit.
The LED driving circuit according to claim 9, wherein the voltage detection unit is a varistor, and the abnormality protection unit is a thermal fuse adjacent to the varistor.
An LED straight tube lamp, comprising a lamp tube, end caps arranged at both ends of the lamp tube, and the LED drive circuit according to any one of claims 1-10, each end cap is provided with two pins, one of which is The pins on the end cover are coupled with the first AC input end, and the pins on the other end cover are coupled with the second AC input end and are short-circuited.