WO2013104251A1

WO2013104251A1 - Alternating current direct constant current drive led light-emitting device

Info

Publication number: WO2013104251A1
Application number: PCT/CN2012/087393
Authority: WO
Inventors: 李东明; 杨冕; 封正勇; 龙文涛; 赵昆; 张明
Original assignee: 四川新力光源股份有限公司
Priority date: 2012-01-10
Filing date: 2012-12-25
Publication date: 2013-07-18
Also published as: CN103200729B; CN103200729A

Abstract

The present invention relates to an alternating current direct constant current drive technology for LED light-emitting devices. In response to the problem of an alternating current direct drive LED light-emitting device in the prior art, disclosed is an alternating current direct constant current drive LED light-emitting device. In the technical solution of the alternating current direct constant current drive LED light-emitting device of the present invention, n strips of LED modules and, constituted by serial-connected constant current units thereof, parallel-connected branches are connected to an output-end of a rectifier circuit; by setting the current value of each constant current unit and switch-off and switch-on voltages thereof, the phenomenon of periodical flickering caused by a change in the voltage of an alternating current is prevented. Because the current of each branch is constant, LEDs in the LED modules do not induce a change in the current due to a change in the junction temperature, thus improving reliability. As known via theoretical analysis, an increase in the number of branches allows the waveform of a drive current to approach a sine wave, thus increasing the power factor and efficiency of the light-emitting device.

Description

AC direct current constant driving LED light-emitting device

The present invention relates to an LED (Light Emitting Diode) illuminating device, and more particularly to an AC direct current constant driving technique for an LED illuminating device.

Background technique

As a new type of solid-state light source, LED is expected to become a new generation of illumination source with its advantages of energy saving, environmental protection and long life. As we all know, the existing LEDs are almost all driven by DC, and our production and living electricity is AC. Therefore, in the currently used LED products, a power converter is required to convert the alternating current into direct current. The introduction of power converters has many negative effects. First, the life of the power converter is much lower than the life of the LED itself, which shortens the service life of the lighting device. Second, the power converter reduces the efficiency of the lighting device. Third, in low power applications, power conversion The device will cause a drop in power factor and an increase in total harmonic distortion of the current. In order to give full play to the advantages of semiconductor lighting, LED light-emitting devices that can be directly driven by alternating current have become the current research hotspots.

In the existing AC LED disclosure technology, most of the LED components are connected in a reverse parallel or bridge rectified circuit topology to meet the AC power drive requirements. However, the AC power fluctuates periodically according to a certain frequency. Due to the presence of the LED's own turn-on voltage, the LED will turn on and emit light when the instantaneous voltage exceeds the turn-on voltage. Conversely, the LED is off and not illuminated. This circuit makes the LED's luminous efficiency very low, and the illuminating flicker occurs with the AC voltage fluctuation.

In the "LIGHT-EMITTING DEVICE HAVING LIGHT-EMITTING ELEMENTS", it is proposed to integrate an LED chip array on a sapphire substrate to provide an AC-powered illumination device, but does not solve the LED illumination. Flashing problem.

US Patent No. 7,489, 086 B2 "AC LIGHT EITTING DIODE AND AC LED DRIVE METHODS AND APPARATUS" provides an AC LED device, which is a device for integrally packaging a plurality of LEDs, utilizing the vision of the human eye The effect of retention is to compensate for the LED illuminating phenomenon caused by the alternating current. This patent does not fundamentally address the phenomenon of illuminating flicker caused by periodic fluctuations in AC voltage.

It can be seen that in the disclosed LED AC drive technology, there is a disadvantage in that the driving current of the LED fluctuates with the fluctuation of the AC voltage, which causes a change in brightness when the LED emits light, and a phenomenon of illuminating and flickering occurs. At the same time, the core of the LED device is a PN junction diode whose IV characteristic is an approximate exponential function. When the voltage across the LED is greater than the turn-on voltage, the current flowing through the PN junction increases exponentially. In the prior art AC driving method, since the constant current circuit is not used, the turn-on voltage of the LED will decrease when the junction temperature of the LED rises, and the forward current of the LED increases sharply due to the constant input voltage, and the LED will be severe when it is severe. The PN junction causes thermal breakdown and permanent damage. Summary of the invention

The technical problem to be solved by the present invention is to provide an LED light-emitting device for direct current constant current driving of alternating current, aiming at the problem that the prior art alternating current directly drives the LED light-emitting device.

The present invention solves the technical problem, and adopts the technical solution that the direct current constant current driving LED lighting device comprises an alternating current input end, a protection unit and a rectifying unit, wherein the first output end of the rectifying unit and the first a first branch, a second branch, an nth branch are connected in parallel between the two outputs, the first branch routing first LED module and the first constant current unit are connected in series, and the second branch is The second LED module and the second constant current unit are formed in series, wherein the nth branch routing nth LED module and the nth constant current unit are connected in series, and each constant current unit is connected to the sampling unit, where n ^ l, and is an integer;

The AC input terminal is used for connecting an alternating current to provide an operating current for the device;

The protection unit is connected to the AC input terminal to provide a protection function for the device;

The rectifying unit is connected to the protection unit, and rectifies the alternating current output by the protection unit;

The sampling unit is configured to sample the output voltage of the rectifying unit, and output a control signal to each constant current unit; each constant current unit is connected to the sampling unit, and the current of the corresponding branch is constant and is connected according to the control signal output by the sampling unit. Or turn off the corresponding branch.

In the technical solution of the illuminating device of the present invention, the parallel branches formed by the n LED modules and the series constant current units are connected at the output end of the rectifier circuit, and the current value of the branch constant current unit is set and turned off, By turning on the voltage, periodic flickering caused by AC voltage changes can be avoided. Since the current of each branch is constant, the LEDs in the LED module do not cause current changes due to changes in junction temperature, which improves the reliability of the LED. Through theoretical analysis, it can be known that the increase in the number of branches can make the driving current waveform close to a sine wave, improving the power factor and efficiency of the illuminating device.

Specifically, the LED module is composed of an LED array.

LED arrays can be used to form high-power LED modules.

Further, the LED array is composed of at least one LED disposed on the same printed circuit board, or at least one LED integrally packaged on the same substrate, or at least one LED integrated on the same semiconductor substrate Composition.

Locating all the LEDs in the LED module on the same printed circuit board is the simplest and economical packaging method under the current process conditions; all LEDs in the LED module are integrally packaged on the same substrate, which means the LED module All the LEDs in the group are sub-packaged and integrated on the same heat-dissipating substrate; all the LEDs in the LED module are integrated on the same semiconductor substrate, which is integrated with the semiconductor on the same semiconductor substrate by the semiconductor integrated circuit process. . These technologies are currently the most mature LED integrated packaging technologies.

Specifically, the LEDs in each LED module are connected in parallel and/or in series.

The appropriate combination of LEDs in the LED module, such as parallel, series or hybrid, is more suitable for direct drive of AC The use environment makes it easy to adjust the current and voltage parameters of each LED module.

Further, the number of LEDs included in the first LED module, the second LED module, and the nth LED module are respectively I ² , 2 ² , . . . , n ² , and the corresponding constant current unit currents are respectively I. 21, ... nl; I is the first constant current unit current.

This distribution of the number of LEDs in the LED module can achieve a multiple relationship of the branch currents, making the total current waveform close to a sine wave, which is beneficial to improve the power factor and efficiency of the light-emitting device.

Further, when 0 2, the same LED belongs to different LED modules at the same time.

The solution can arrange the LEDs in each LED module in a staggered manner, so that the same or several LEDs belong to different LED modules at the same time, realize multiplexing of LEDs, can reduce the number of LEDs of the light-emitting device, and improve the uniform brightness of the light-emitting device. Sex, which helps to overcome the flicker phenomenon.

Specifically, the protection unit includes a fuse and/or a varistor, the fuse is connected in series at the AC input end, and the varistor is connected in parallel at the AC input end.

Fuses are commonly used current-limiting protection components, and varistors are commonly used voltage-limiting protection components. Their combination can achieve the most basic current limiting and voltage limiting protection, and the cost is low, the installation is convenient, and secondary integration is facilitated.

Further, the protection unit further includes a common mode choke coil and/or a gas discharge tube, the common mode choke coil is connected in series at the AC input end, and the gas discharge tube is connected in parallel at the AC input end.

The common mode choke and the gas discharge tube are added, and the common mode choke can suppress the common mode interference, and the gas discharge tube can protect the illumination device from being damaged by lightning.

Specifically, the rectifying unit is composed of a full-wave rectifying circuit or a half-wave rectifying circuit composed of a rectifying diode.

The rectifier diode is used as a rectifying component, which is small in size and light in weight, and is convenient for secondary integration packaging.

Specifically, the sampling unit is composed of a resistor network.

The resistor network is ideal for collecting DC parameters, making it easy to set the action point at which the constant current unit is turned off and on.

The invention has the beneficial effects that the LED module is directly driven by the alternating current power, the circuit is simple, the volume is small, the weight is light, and the cost is low. By properly presetting the current of each branch and the switching voltage, the LED lighting device can periodically reduce the fluctuation of the AC power fluctuation, and when the instantaneous voltage of the AC current is too high, the constant current unit is turned off, and the LED module does not emit light, thereby improving the utilization of the power supply. Efficiency, reducing power consumption. At the same time, due to the constant current control, the LED module is prevented from being burnt due to the junction temperature change and the current is too large, which prolongs the service life of the device.

DRAWINGS

Figure 1 is a block diagram showing the structure of the present invention;

Figure 2 is a circuit schematic diagram of Embodiment 1;

Figure 3 is a schematic view of Embodiment 2;

Figure 4 is a schematic view of Embodiment 3; Figure 5 shows the voltage and current waveforms.

detailed description

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

The LED light-emitting device of the direct current constant current driving of the present invention is shown in FIG. 1 and includes an AC input terminal 1, a protection unit 2, a rectifying unit 3, and a first output terminal 31 of the rectifying unit 3 (usually a positive electrode). And a first branch, a second branch, ... an nth branch connected in parallel with the second output 32 (usually the negative pole). The first routing first LED module 51 and the first constant current unit 61 are connected in series, and the second routing second LED module 52 and the second constant current unit 62 are connected in series, ... the nth routing The nth LED module 5n and the nth constant current unit 6n are connected in series, and each constant current unit is connected to the sampling unit, where η 1, and is an integer. The AC input terminal 1 is used for connecting AC to provide operating current for the device; the protection unit 2 is connected to the AC input terminal to provide protection for the device; The rectification unit 3 is connected to the protection unit 2, and rectifies and outputs the AC power output from the protection unit 2 Sine wave pulse current (as shown in FIG. 5a); sampling unit 4 is used for sampling the output voltage of the rectifying unit, and outputting a control signal to each constant current unit; each constant current unit is connected with the sampling unit 4, and a constant corresponding branch The current is turned on or off according to the control signal output from the sampling unit 4.

The following briefly describes the working principle of the present invention:

AC mains (usually sinusoidal AC) enters protection unit 2 through AC input interface 1 and is rectified by rectification unit 3 to become a sinusoidal pulse voltage. The voltage waveform is shown in Figure 5a. In an alternating current period T, as the input voltage rises, the first LED module 51 is turned on, the first LED module 51 enters the working state, and the current gradually increases, after reaching the preset current of the first constant current unit 61. The preset current operates in a constant current state. As the voltage continues to rise, the voltage reaches the preset turn-off voltage of the first constant current unit 61, the first constant current unit 61 is turned off, and the first LED module 51 does not emit light. At this time, the second constant current unit 62 is turned on, the second LED module 52 starts to work, and the second LED module 52 enters the constant current state, and the current set by the second constant current unit 62 maintains the constant current working state. The voltage continues to rise, the second constant current unit 62 is turned off, and so on, until the nth LED module 5n starts operating, and the front constant current cells are all turned off. If the constant current of the first constant current unit 61 is set to I, the constant current of the second constant current unit 62 is 21, ... the constant current of the η constant current unit is nl. Theoretically, the more packets, the more the current waveform Close to the sine wave, as shown in Figure 5b, the higher the power factor, the higher the efficiency, but the more complex the circuit, the more difficult it is to place and route. Therefore, in practical applications, a limited number of constant current units and a corresponding number of LED modules are selected to form a finite branch.

Example 1

As shown in FIG. 2, the protection unit 2 of this example is composed of a fuse F and a varistor VR. The fuse F is connected in series on the phase line L of the AC input terminal 1, and the varistor VR is connected in parallel with the phase line L of the AC input terminal 1 and Between the zero line N. The protection unit 2 is connected to the rectifying unit 3 constituted by the full-wave rectifying circuit D1, and the output ends of the rectifying unit 3 are connected in parallel with four branches.

The first LED module and the first constant current unit are connected in series, and the first LED module is composed of one LED 11. The positive terminal is connected to the positive pole of the rectifier circuit D1, and the negative terminal is connected to the cathode of the rectifier circuit D1 through the first constant current unit. The sampling in this example consists of a resistor network, including resistors R1 to R8. The resistor R1 and the resistor R2 are connected in series and then connected in parallel between the positive pole and the negative pole of the rectifier circuit D1. The connection point of the resistor R1 and the resistor R2 is a sampling point of the first constant current unit, and is connected to the control end of the first constant current unit. In the second branch of this example, the second LED module is composed of a 2 X 2 array of 4 LEDs, including LED21, LED22, LED31 and LED32, which are connected in parallel with two LEDs and two parallel poles in parallel. Way to connect, as shown in Figure 2. The positive terminal of the second LED module is connected to the positive pole of the rectifier circuit D1, and the negative terminal is connected to the cathode of the rectifier circuit D1 through the second constant current unit. The resistor R3 is connected in series with the resistor R4 in parallel between the positive pole and the negative pole of the rectifier circuit D1, and the connection point of the resistor R3 and the resistor R4 is a sampling point of the second constant current unit, and is connected to the control end of the second constant current unit. The third LED module in the third branch of this example consists of a 3 X 3 array of 9 LEDs, including LED41, LED42, LED43; LED5 K LED52, LED53; LED6 K LED62, LED63. These LEDs are connected in parallel with three sets of the same poles in the same direction, see Figure 2. The positive terminal of the third LED module is connected to the positive pole of the rectifier circuit D1, and the negative terminal is connected to the negative pole of the rectifier circuit D1 through the third constant current unit. The resistor R5 is connected in series with the resistor R6 in parallel between the positive pole and the negative pole of the rectifier circuit D1, and the connection point of the resistor R5 and the resistor R6 is a sampling point of the third constant current unit, and is connected to the third constant current unit control terminal. In the fourth branch of this example, the fourth LED module is composed of a 4 X 4 array of 16 LEDs, including LED71, LED72, LED73, LED74; LED8 K LED82, LED83, LED84; rectifier circuit Dl negative LED91, LED92 , LED93, LED94; LEDOK LED02, LED03, LED04. These LEDs are connected in parallel with four groups of same poles in the same direction, see Figure 2. The positive terminal of the fourth LED module is connected to the positive pole of the rectifier circuit D1, and the negative terminal is connected to the fourth constant current unit. The resistor R7 is connected in series with the resistor R8 in parallel between the positive pole and the negative pole of the rectifier circuit D1, and the connection point of the resistor R7 and the resistor R8 is a sampling point of the fourth constant current unit, and is connected to the control terminal of the fourth constant current unit. In this example, the negative electrode of the rectifier circuit D1 is a common ground terminal.

The plug-in is connected to the power grid, and the illuminating device of the present example obtains AC power, and the AC power passes through the protection unit, and is rectified into a direct current by a rectifying unit (strictly speaking, a sinusoidal pulsed direct current, the waveform is as shown in FIG. 5a), and is supplied to the voltage sampling unit. Constant current unit and LED module. In each AC cycle T, the output voltage of the rectifier circuit D1 rises from zero. When the voltage rises to the turn-on voltage of the first LED module, the first constant current unit is turned on, and the first LED module starts to emit light. Working status. The voltage continues to rise, and the constant current unit 1 operates at a set constant current of 20 mA, so that the current of the first LED module reaches a rated current of 20 mA. When the voltage rises to a preset turn-off voltage, the first constant current unit is turned off, the first LED module stops working, the first LED module is turned off, and the second LED module starts to emit light, and enters a working state. The voltage is raised, and the second constant current unit operates at a set constant current of 40 mA, so that the current of the second LED module reaches a rated current of 40 mA. When the voltage rises to the second constant current unit for a predetermined off voltage, the second constant current unit is turned off, the second LED module stops working, and the third LED module starts to work, and as the voltage rises, The third constant current unit operates at a set constant current of 60 mA to bring the current of the third LED module to a rated current of 60 mA. When the voltage rises to the preset turn-off voltage, the third constant current unit is turned off, the fourth constant current unit is turned on, the fourth LED module starts to work, and when the voltage continues to rise, the fourth constant current unit has a constant current. 80mA working, The fourth LED module current is brought to a rated current of 80 mA. As shown in Fig. 5b, the current waveform is a schematic diagram of the current example. It can be seen that the current is multiplied at different stages, and the waveform is close to sinusoidal. The illuminating device of this example has high efficiency and power factor. The fourth constant current unit also has a protection function, and when the voltage exceeds the preset off voltage, the fourth constant current unit is turned off. The LED modules in the entire illuminating device are all turned off, and the illuminating device is protected from damage.

In this example, the LED array in each LED module (the LED module of the first branch in this example can also be regarded as a 1 X 1 LED array), which may be composed of LEDs arranged on the same printed circuit board, or They are integrated and packaged on the same heat-dissipating substrate by integrated packaging technology, and they can also be integrated on the same semiconductor substrate by using an integrated circuit process.

Example 2

FIG. 3 is a schematic diagram of the circuit of the present embodiment. It can be seen that the structure of the LED module is the same as that of the first embodiment except that the structure of the LED module and the connection manner thereof are different from that of the first embodiment. In the following, only the structure of the LED modules of the four branches will be described. For other structures and their working processes, please refer to the description of Embodiment 1, which will not be described here. The first LED module in the first branch of the example is composed of an LED 31, the positive end of the first LED module is connected to the positive pole of the rectifier circuit D1, and the negative end of the first LED module is connected to the rectifier circuit through the first constant current unit. D1 negative electrode. The second LED module in the second branch of this example includes LED31, LED32, and LED2K LED22. When the first constant current unit is turned off, the four LEDs form an array of 2 X 2 , wherein the LED 31 and the LED 32 are connected in series in the same direction, and the LED 21 and the LED 22 are connected in series in the same direction. The second LED module has a positive terminal connected to the positive terminal of the rectifier circuit D1, and a negative terminal connected to the negative terminal of the rectifier circuit D1 through the second constant current unit. The third LED module of this example includes LED31, LED32, LED33, LED2K LED22, LED23, LED1 K LED12, and LED 13 total 9 LEDs. When the first constant current unit and the second constant current unit are both turned off, the 9 LEDs constitute an array of 3 X 3 , wherein LED31, LED32, and LED33 are connected in series in the same direction, and LED2K LED22 and LED23 are connected in series in the same direction. LED1 K LED12 and LED13 are connected in series in the same direction. These three sets of the same pole form a third LED module. The positive terminal of the third LED module is connected to the positive terminal of the rectifier circuit D1, and the negative terminal is connected to the negative terminal of the rectifier circuit D1 through the third constant current unit. Similarly, when the first constant current unit, the second constant current unit and the third constant current unit are all turned off in FIG. 3, four groups of LED31, LED32, LED33, LED34, LED2K LED22, LED23, LED24 in the same direction are connected in series. The LED array of LED1 K LED12, LED13, LED14, LEDOK LED02, LED03, LED04 constitutes the fourth LED module of this example, the positive terminal of the fourth LED module is connected with the positive pole of the rectifier circuit D1, and the negative terminal passes The fourth constant current unit is connected to the negative terminal of the rectifier circuit D1. In this example, each branch circuit is multiplied as in the first embodiment. If the first branch current is I, the other branches are 21, 31, and 41 in sequence.

In this example, the LEDs in each LED module adopt a combination of series and parallel, and some LEDs belong to multiple LED modules at the same time. As shown in Fig. 3, LED 31 belongs to all LED modules at the same time. LED22 and LED32 belong to the second, third and fourth LED modules at the same time, and LED33, LED23 and LED13 are the third and fourth LED modules at the same time. With this multiplexing structure, the number of light-emitting units is greatly reduced, the cost of the light-emitting device is reduced, and the flicker phenomenon is advantageously overcome.

Example 3 As shown in FIG. 4, the circuit diagram of this example is further optimized according to the second embodiment, and the LED module connection manner is further optimized. Four of the four branches are composed of 16 LEDs, and 4 X 4 is used. Matrix topology. In this example, the first LED module is composed of an LED array of LED01, LED1, KLED21 and LED31, which are composed of 4 LEDs connected in parallel. In this example, the second LED module is composed of LED X1, LED1 K LED2K LED31, LED02, LED12, LED22, and LED32, which are composed of 8 X 4 arrays of LEDs connected in series and in parallel. The third LED module of this example consists of a 3×4 array consisting of LED01, LED1 K LED2K LED31, LED02, LED12, LED22, LED32, LED03, LED13, LED23, LED33 with 12 LEDs connected in series and in parallel. The module consists of 4×4 arrays consisting of LED01, LED1, K2, LED2, LED31, LED02, LED12, LED22, LED32, LED03, LED13, LED23, LED33, LED04, LED14, LED24, LED34, 16 LEDs connected in series and in parallel, other parts For the connection relationship and working principle, please refer to the description of the above embodiment. The biggest characteristic of this example circuit is that the currents of the branches are the same, that is, the currents set by all the constant current units are the same, which are four times of the constant current driving current of one LED.

From the above detailed explanation, it can be seen that the voltage sampling unit of the present invention monitors the input voltage and also has a protection function for the LED module. When the AC voltage fluctuates greatly, the constant current unit can also be disconnected in time to protect the LED module from damage due to excessive current. The constant current unit of the present invention may be constructed using separate components and/or integrated circuits, and is required to have a switching control function (which can be turned off and on). Since the specific circuit is well-known in the art, the present invention will not be described in detail.

It should be noted that, although the above embodiments have described the structure of the present invention in detail, the present invention is not limited to the above embodiments, and any alternative structure that can be conceived by those skilled in the art from the above embodiments without any inventive work, It belongs to the scope of protection of the present invention.

Claims

WO 2013/104251 Claim PCT/CN2012/087393

An alternating current direct current driving LED lighting device, comprising an alternating current input end, a protection unit and a rectifying unit, wherein a first branch is connected in parallel between the first output end and the second output end of the rectifying unit The second branch, the nth branch, the first branch first LED module and the first constant current unit are connected in series, and the second branch second LED module and the second constant current unit are connected in series The nth branch of the nth LED module and the nth constant current unit are connected in series, and each constant current unit is connected to the sampling unit, where _η ι, and is an integer;

2. The alternating current direct current driving LED lighting device according to claim 1, wherein each of the LED modules is composed of an LED array.

3. The alternating current direct current driving LED lighting device according to claim 2, wherein the LED array is composed of at least one LED disposed on the same printed circuit board, or is integrally packaged on the same substrate. At least one LED is formed, or at least one LED integrated on the same semiconductor substrate.

4. The alternating current direct current driving LED lighting device according to claim 2, wherein the LEDs in each LED module are connected in parallel and/or in series.

The LED light-emitting device driven by the alternating current direct current constant according to claim 2, wherein the number of LEDs included in the first LED module, the second LED module, ... the nth LED module is I ² , 2 ² , ... n ² , the corresponding constant current unit currents are I, 21, ... nl; I is the first constant current unit current.

6. The alternating current direct current driving LED lighting device according to claim 2, wherein when n 2 , the same LED belongs to different LED modules at the same time.

7. The alternating current direct current driving LED lighting device of claim 1, wherein the protection unit comprises a fuse and/or a varistor, the fuse being connected in series at an alternating current input, the varistor Parallel to the AC input.

8. The alternating current direct current driving LED lighting device of claim 7, wherein the protection unit further comprises a common mode choke and/or a gas discharge tube, wherein the common mode choke is connected in series At the AC input, the gas discharge tube is connected in parallel at the AC input end.

The LED light-emitting device for direct current constant current driving according to claim 1, wherein the rectifying unit is constituted by a full-wave rectifying circuit or a half-wave rectifying circuit composed of a rectifying diode. WO 2013/104251 Claim PCT/CN2012/087393

10. The alternating current direct current driving LED lighting device according to claim 1, wherein the sampling unit is constituted by a resistor network.