CN113923823A

CN113923823A - Multi-path LED output control circuit based on synchronous out-of-phase control

Info

Publication number: CN113923823A
Application number: CN202110106708.5A
Authority: CN
Inventors: 高文飞; 杨志民; 赖毅平
Original assignee: Shanghai Moons' Automation Control Co ltd
Current assignee: Shanghai Moons' Automation Control Co ltd
Priority date: 2021-01-26
Filing date: 2021-01-26
Publication date: 2022-01-11

Abstract

The invention relates to a multi-channel LED output control circuit based on synchronous out-of-phase control. The circuit includes at least two LED output circuits and a processor. The processor is connected with each LED output circuit through a synchronous signal output interface, so the The synchronization signals received by the various LED output circuits are staggered by a phase angle of 360°/N, where N is the number of LED output circuits; the processor controls the multi-channel LED output circuits through synchronous out-of-phase control technology, Make the multi-channel LED output circuits work at the same frequency, and stagger each channel by the set phase angle, so that the sum of the total ripple current is 0. Compared with the prior art, the present invention has the advantages of eliminating ripple current and the like.

Description

Multi-path LED output control circuit based on synchronous out-of-phase control

Technical Field

The invention relates to an LED output circuit, in particular to a multi-path LED output control circuit based on synchronous out-of-phase control.

Background

As shown in fig. 1, in the scheme of the main multi-channel independent output LED driving circuit in the market, it can be seen that each channel is independently formed into an output, because as long as the power supply is a switching power supply scheme, the output of the power circuit inevitably has ripple current, and even though the power circuit passes through the inductance-capacitance filtering circuit or the single capacitance filtering circuit, stroboscopic which is consistent with the operating frequency of the power circuit still exists on the LED.

For multi-path output, if the output is completely independent between each power circuit, the difference frequency phenomenon caused by different circuit frequencies due to device precision can even introduce low-frequency ripple current.

If the two-way output circuit is in the fixed frequency operation mode, the power circuit 1 operates at the 45kHz switching frequency and the power circuit 2 operates at the 46kHz switching frequency due to device variations. Then when both circuits are operating simultaneously there will be a low frequency envelope of 1kHz on the total light efficiency across the two LEDs, as shown in figure 2, which will result in the appearance of low frequency ripples. Fig. 3 shows the internal details of the envelope.

In fig. 2 it can be seen that the output current of the power circuit 1 is

1+0.2*Sin(2π*45000t)

And the output current of the power circuit 2 is

1+0.2*Sin(2π*46000t)

And the two equations are added, and the total current is obtained according to a sine wave superposition formula:

2+0.4*Sin(2π*45500t)*Cos(2π*500t)

then a low frequency ripple appears in the light efficiency of the LED.

Disclosure of Invention

The present invention is directed to overcome the above-mentioned drawbacks of the prior art, and to provide a multi-LED output control circuit based on synchronous out-of-phase control for eliminating ripple current.

The purpose of the invention can be realized by the following technical scheme:

according to one aspect of the invention, a multi-path LED output control circuit based on synchronous out-of-phase control is provided, the circuit comprises at least two paths of LED output circuits and a processor, the processor is connected with each path of LED output circuit through a synchronous signal output interface, synchronous signals received by each path of LED output circuit are staggered by a phase angle of 360 degrees/N, wherein N is the number of paths of the LED output circuits;

the processor controls the multiple paths of LED output circuits through a synchronous out-of-phase control technology, so that the multiple paths of LED output circuits work under the same frequency, and each path is staggered by a set phase angle, and the sum of total ripple current is 0.

As a preferable technical scheme, the LED output circuit has two paths, and the phase angle is 180 °.

As a preferable technical solution, the number of the LED output circuits is three, and the phase angle is 120 °.

Preferably, the LED output circuits are four-way, and the phase angle is 90 °.

As a preferred technical scheme, each path of LED output circuit comprises an LED driving power circuit, an output filter inductor, an output filter capacitor and a diode, the LED driving power circuit is respectively connected with one end of the output filter inductor, one end of the output filter capacitor and the negative electrode of the diode, and the other end of the output filter inductor is respectively connected with the other end of the output filter capacitor and the positive electrode of the diode.

Preferably, the ripple wave is a sine wave.

As a preferred technical solution, the ripple wave adopts a square wave.

Preferably, the ripple wave is a triangular wave.

As a preferred technical scheme, the processor adopts a singlechip.

As the preferred technical scheme, the single chip microcomputer is provided with an interface for outputting the synchronous signals.

Compared with the prior art, the invention has the following advantages:

according to the invention, because each path is staggered by 360 DEG/N, wherein N is the number of output channels, the total ripple current is superposed on the LED light output effect to show that the ripple is 0, so that the problem that the LED driving power supply is puzzled to pursue low ripple current is solved with little cost.

Drawings

FIG. 1 is a circuit diagram of a conventional LED driving circuit;

FIG. 2 is a waveform diagram of an output circuit of a conventional LED driving circuit;

FIG. 3 is a schematic diagram of the internal details of the low frequency envelope of FIG. 2;

FIG. 4 is a circuit diagram of the present invention;

FIG. 5 is a waveform diagram of the output current of the present invention.

Detailed Description

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 some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

As shown in fig. 4, a multi-channel LED output control circuit based on synchronous out-of-phase control includes at least two LED output circuits and a processor, where the processor is connected to each of the LED output circuits through a synchronous signal output interface, and the synchronous signals received by each of the LED output circuits are staggered by a phase angle of 360 °/N, where N is the number of LED output circuits;

Each path of LED output circuit comprises an LED driving power circuit, an output filter inductor, an output filter capacitor and a diode, the LED driving power circuit is respectively connected with one end of the output filter inductor, one end of the output filter capacitor and the negative electrode of the diode, and the other end of the output filter inductor is respectively connected with the other end of the output filter capacitor and the positive electrode of the diode.

The technology introduced by the invention is that synchronous out-phase processing is added in a multi-path output circuit, namely, the multi-path output power circuit works under the same frequency through single chip microcomputer control, and each path is staggered by a certain phase angle, so that the sum of the total ripple current is 0. Specifically, for a two-output circuit, then each is staggered 180 ° from each other, for a three-output circuit, each is staggered 120 ° from each other, for a four-output circuit, each is staggered 90 °, and so on, so that when the sum currents add together, the ripple current is 0.

Each path is output with a synchronous signal by the singlechip, and the two synchronous signals are controlled to be staggered by 180 degrees, so that the superposed total current is finally obtained as shown in fig. 5.

Wherein the current of the power circuit 1 is:

1+0.2*Sin(2π*45000t)；

the current of the power circuit 2 is:

1+0.2*Sin(2π*45000t+180°)；

and the two equations are added, and the total current is obtained according to a sine wave superposition formula: 2.

that is to say, the total ripple current is output to be 0, so that the total ripple current is greatly reduced, and the stroboscopic of the light is optimized.

Meanwhile, the invention is also suitable for the scheme of 3-path and 4-path output. Wherein, for 3-path output, the synchronous signals are mutually staggered by 120 degrees, for 4-path output, the synchronous signals are mutually staggered by 90 degrees, and finally the obtained total current also meets the condition that the ripple current is 0.

The invention is also applicable to the wave forms with the ripple waves in the forms of square waves, triangular waves and the like, and the principle is the same as that of sine waves.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A multi-path LED output control circuit based on synchronous out-of-phase control is characterized by comprising at least two paths of LED output circuits and a processor, wherein the processor is connected with each path of LED output circuit through a synchronous signal output interface, synchronous signals received by each path of LED output circuit are staggered by a phase angle of 360 DEG/N, and N is the number of paths of the LED output circuits;

2. The multi-path LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the LED output circuit is two-path, and the phase angle is 180 °.

3. The multi-LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the LED output circuit is three-way, and the phase angle is 120 °.

4. The multi-LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the LED output circuit is four-way, and the phase angle is 90 °.

5. The multi-path LED output control circuit based on synchronous out-of-phase control according to claim 1, wherein each path of LED output circuit comprises an LED driving power circuit, an output filter inductor, an output filter capacitor and a diode, the LED driving power circuit is respectively connected with one end of the output filter inductor, one end of the output filter capacitor and the cathode of the diode, and the other end of the output filter inductor is respectively connected with the other end of the output filter capacitor and the anode of the diode.

6. The multi-LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the ripple is sine wave.

7. The multi-LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the ripple is square wave.

8. The multi-LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the ripple is triangular wave.

9. The multi-path LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the processor employs a single chip microcomputer.

10. The multi-path LED output control circuit based on synchronous out-of-phase control as claimed in claim 1, wherein the single chip is provided with an interface for synchronous signal output.