CN216122952U

CN216122952U - LED drive circuit with improved EMC

Info

Publication number: CN216122952U
Application number: CN202121798579.2U
Authority: CN
Inventors: 吕少华; 曹胜军; 蒲纪忠; 甘彩英; 赵艺佼
Original assignee: CH Lighting Technology Co Ltd
Current assignee: CH Lighting Technology Co Ltd
Priority date: 2021-08-03
Filing date: 2021-08-03
Publication date: 2022-03-22
Anticipated expiration: 2031-08-03

Abstract

The utility model discloses an LED drive circuit capable of improving EMC, which comprises a rectifying unit, a common mode filtering unit and a constant current unit which are connected in sequence, wherein the common mode filtering unit comprises: two parallel diode groups, each diode group comprising at least two diodes connected in series; a first capacitor and a second capacitor connected in series, the first capacitor being coupled between one set of adjacent diodes, the second capacitor being coupled between another set of adjacent diodes; and one end of the third capacitor is coupled with the second capacitor, and the other end of the third capacitor is coupled with the ground. This application is through setting up common mode filter unit, through first electric capacity and the second electric capacity of establishing ties in the common mode filter unit, suppresses common mode interference, and then improves EMC.

Description

LED drive circuit with improved EMC

Technical Field

The application relates to the field of LED driving, in particular to an LED driving circuit with improved EMC.

Background

As a novel illumination light source, the LED is more and more widely applied to various occasions due to the outstanding advantages of energy conservation, environmental protection, high luminous efficiency, long service life and the like. In the LED, an LED driving circuit is used to drive an LED load, and plays an important role. However, in a specific using process, because electromagnetic interference exists, the influence on the LED driving circuit is large, and the LED driving circuit is easy to be unstable.

SUMMERY OF THE UTILITY MODEL

The utility model provides an LED drive circuit with improved EMC, which solves the problem of instability of the LED drive circuit and improves the overall EMC.

LED drive circuit with improve EMC, including rectifier unit, common mode filter unit and the constant current unit that connects gradually, common mode filter unit includes:

two parallel diode groups, each diode group comprising at least two diodes connected in series;

a first capacitor and a second capacitor connected in series, the first capacitor being coupled between one set of adjacent diodes, the second capacitor being coupled between another set of adjacent diodes;

and one end of the third capacitor is coupled with the second capacitor, and the other end of the third capacitor is coupled with the ground.

Several alternatives are provided below, but not as an additional limitation to the above general solution, but merely as a further addition or preference, each alternative being combinable individually for the above general solution or among several alternatives without technical or logical contradictions.

Optionally, each diode group has two diodes connected in series.

Optionally, a fifth capacitor is coupled between the two output ends of the rectifying unit.

Optionally, the rectifying unit is a bridge rectifier circuit.

Optionally, the LED driving circuit includes a live wire access end and a zero line access end, and a fourth capacitor is coupled between the live wire access end and the zero line access end.

Optionally, a first inductor and a first resistor connected in parallel are disposed between the live wire access end and the rectifying unit.

Optionally, the constant current unit includes a constant current chip coupled to the common mode filter unit through a power supply circuit.

Optionally, the power supply circuit includes a second resistor and a third resistor connected in series in sequence.

Optionally, the constant current unit includes a freewheeling circuit controlled by the constant current chip.

Optionally, the free-wheeling circuit comprises a first diode.

The utility model is provided with the common mode filtering unit, and common mode interference is inhibited through the first capacitor and the second capacitor which are connected in series in the common mode filtering unit, so that EMC is improved.

Drawings

FIG. 1 is a schematic diagram of an LED driving circuit with improved EMC according to the present application;

FIG. 2 is a circuit schematic of a prior art LED driver circuit;

fig. 3 is a schematic circuit diagram of an LED driving circuit with improved EMC according to the present application.

The reference numerals in the figures are illustrated as follows:

1. a constant current chip;

10. a rectifying unit;

20. a common mode filtering unit;

30. and a constant current unit.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present.

Unless defined otherwise, 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 application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in fig. 2, the conventional common LED driving circuit has a problem that the whole circuit is unstable due to electromagnetic signal interference in the practical application process.

In order to improve the anti-interference capability of the circuit, the utility model provides an LED driving circuit with improved EMC, which comprises a rectifying unit 10, a common mode filtering unit 20 and a constant current unit 30 which are connected in sequence as shown in FIGS. 1 and 3.

The common mode filter unit 20 includes two parallel diode sets, a first capacitor C1 and a second capacitor C2 connected in series, and a third capacitor C3. Each diode group comprises at least two diodes connected in series; the first capacitor C1 is coupled between adjacent diodes of one group, the second capacitor C2 is coupled between adjacent diodes of the other group, and when an interference signal is generated, common mode interference is suppressed by the first capacitor C1 and the second capacitor C2; the third capacitor C3 is coupled to the second capacitor C2 at one end and to ground at the other end for further filtering.

According to the LED common-mode power supply, the commercial power is rectified through the rectifying unit 10, the alternating current is converted into the direct current, the direct current is input into the common-mode filtering unit 20 to inhibit common-mode interference and filter, a relatively gentle voltage is obtained, and finally the output voltage is input into the constant current unit 30 to enable the constant current unit to obtain stable direct current to supply the LEDs to normally work.

The rectifying unit 10 and the constant current unit 30 of the present application may adopt the prior art, and in this embodiment, the rectifying unit 10 is a bridge rectifier circuit.

In one embodiment, a fifth capacitor C5 is coupled between the two output terminals of the rectifying unit 10. One output terminal is further coupled to the common-mode filtering unit 20, and the other output terminal is connected to ground.

In one embodiment, each diode group has two diodes connected in series. In the common mode filtering unit 20, as shown in fig. 3, an output end of the rectifying unit 10 is coupled to a fifth diode D5 and a fourth diode D4 which are connected in series, two ends of the fifth diode D5 and two ends of the fourth diode D4 are respectively connected in parallel to a seventh diode D7 and a sixth diode D6 which are connected in series, wherein one end of a first capacitor C1 is coupled between the fifth diode D5 and the fourth diode D4, and one end of a second capacitor C2 is coupled between the seventh diode D7 and the sixth diode D6.

In one embodiment, the LED driving circuit includes a live access and a neutral access, and a fourth capacitor C4 is coupled between the live access and the neutral access. Wherein, two input terminals of the rectifying unit 10 are coupled to the live input terminal and the zero input terminal respectively

In an embodiment, a first inductor L1 and a first resistor R1 are disposed in parallel between the live terminal and the rectifying unit 10. In order to ensure the safety of the whole circuit, a fuse F1 is also arranged at the live wire access end.

In one embodiment, a voltage dependent resistor RV2 coupled to ground is disposed between the common mode filter unit 20 and the constant current unit 30.

The constant current unit 30 includes a constant current chip coupled to the common mode filter unit 20 through a power supply circuit. The power supply circuit comprises a second resistor R2 and a third resistor R3 which are sequentially connected in series. The other end of the third resistor R3 is coupled to the VCC terminal of the constant current chip 1, and is connected to ground through a sixth diode C6 and a sixth resistor R6 connected in series. The OVP terminal of the constant current chip 1 is connected to the ground through the fourth resistor R4, the junction of the sixth diode C6 and the sixth resistor R6, and the fifth resistor R5. The GND terminal of the constant current chip 1 is coupled to a node between the fourth resistor R4 and the fifth resistor R5. The CS terminal of the constant current chip 1 is coupled to ground through a seventh capacitor C7 and an eighth resistor R8, wherein a junction of the seventh capacitor C7 and the eighth resistor R8 is coupled to the output terminal of the common mode filter unit 20 through a tenth resistor R10 and a ninth resistor R9 connected in series.

In one embodiment, the constant current unit 30 includes a freewheel circuit controlled by the constant current chip 1, and the freewheel circuit includes the first diode D1. The other ports of the constant current chip 1 are connected to each other and are respectively coupled to the anode of the first diode D1 and the inductor T1, and the cathode of the first diode D1 is coupled to the output terminal of the common mode filter unit 20.

In an embodiment, the two ends of the first diode D1 are further connected in parallel with an eighth capacitor C8, an eleventh resistor R11, a ninth electrolytic capacitor C9, a tenth electrolytic capacitor C10, an eleventh electrolytic capacitor C11, and a seventh resistor R7, which are connected in series. The negative electrode of the ninth electrolytic capacitor C9 is connected with the ground through the twelfth capacitor C12 in series, and the other end of the inductor T1 is coupled with the junction of the ninth electrolytic capacitor C9 and the twelfth capacitor C12.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features. When technical features in different embodiments are represented in the same drawing, it can be seen that the drawing also discloses a combination of the embodiments concerned.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application.

Claims

1. LED drive circuit with improve EMC, including rectifier unit, common mode filter unit and the constant current unit that connects gradually, its characterized in that, common mode filter unit includes:

2. The LED driving circuit of claim 1, wherein each diode group has two diodes connected in series.

3. The LED driving circuit according to claim 1, wherein a fifth capacitor is coupled between the two output terminals of the rectifying unit.

4. The LED driving circuit according to claim 3, wherein the rectifying unit is a bridge rectifier circuit.

5. The LED driver circuit of claim 1, wherein the LED driver circuit comprises a hot access and a neutral access, and wherein a fourth capacitor is coupled between the hot access and the neutral access.

6. The LED driving circuit according to claim 5, wherein a first inductor and a first resistor are arranged in parallel between the live line input end and the rectifying unit.

7. The LED driving circuit according to claim 1, wherein the constant current unit comprises a constant current chip coupled to the common mode filter unit via a power supply circuit.

8. The LED driving circuit according to claim 7, wherein the power supply circuit comprises a second resistor and a third resistor connected in series in sequence.

9. The LED driving circuit according to claim 7, wherein the constant current unit comprises a freewheeling circuit controlled by a constant current chip.

10. The LED driver circuit of claim 9, wherein the freewheel circuit includes a first diode.