KR101473912B1 - High powered light emitting diode lighting using a LED driver - Google Patents

Abstract

An AC power direct lighting type high power LED lighting device is provided. A high-power LED lighting device according to the present invention includes a rectifying circuit connected to an AC power source and configured by a bridge diode for full-wave rectification, a first LED comprising at least one LED supplied with current from the AC power source through the rectifying circuit A first LED driver for controlling a current flowing in the first LED group and a second auxiliary driver for allowing a current exceeding a capacity of the LED driver among the currents flowing in the first LED group to flow to the ground terminal without passing through the LED driver, And a driving circuit.

Description

[0001] The present invention relates to a high-power LED lighting device using a single LED driver,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED lighting apparatus, and more particularly, to a high output LED lighting apparatus using one LED driver for low output control.

An LED (Light Emitting Diode) is a semiconductor element that emits light when a voltage is applied in the forward direction. The emission principle of LEDs utilizes the electroluminescence effect, and the lifetime of the LEDs is relatively longer than that of incandescent lamps. The luminescent color varies depending on the material to be used, and can emit light in the ultraviolet region and in the visible region and the infrared region. Due to the advantages of such LEDs, LEDs are utilized in various fields. In particular, the brightness of the LEDs is adjusted by varying the current supplied to the LEDs based on a constant voltage, or a current control method So that it is widely used as a lighting device.

Generally, an LED lighting device can be broadly divided into a DC power supply method using a DC output power using an AC / DC converter and an AC direct type method in which an AC power supply is directly inputted and high frequency switching or a pulse current is directly used. In recent years, as the weight, space, and price of LED lighting devices have been increasingly demanded, research on a simple AC direct type of driving circuit is being conducted rather than a DC power supply method which is heavy in weight and relatively more space.

An AC direct-coupled LED lighting fixture can be an IC package, which is a circuit element integrated into a drive circuit. The IC package for driving the LED lighting apparatus controls the outgoing electric power of about 5 to 20 W due to the power consumption limit. A plurality of driving ICs (drive ICs, LED drivers) are used in parallel to drive a high-output AC direct-coupled LED lighting apparatus. However, this method increases the implementation cost, .

Korean Patent Laid-Open No. 10-2001-0093337 (Oct. 27, 2001)

SUMMARY OF THE INVENTION It is an object of the present invention to provide an LED driving apparatus and method that can reduce implementation costs and increase operation reliability.

An AC power direct lighting type LED (Light Emitting Diode) illuminator according to an embodiment of the present invention includes a rectifier circuit connected to an AC power source and configured by a bridge diode for full-wave rectification, and a rectifier circuit A first LED group including at least one LED, and an LED driver for controlling a current flowing in the first LED group and a current exceeding a capacity of the LED driver among currents flowing in the first LED group, And a first auxiliary driving circuit for allowing the current to flow to the ground terminal without passing through the ground terminal.

A second LED group consisting of at least one LED connected in series with the first LED group and the AC power supply, and a second LED group including a current exceeding the capacity of the LED driver among the currents flowing in the second LED group, And a second auxiliary driving circuit for allowing the current to flow to the ground terminal without passing through.

Wherein the LED driver includes a first switch for opening / closing a connection between a connection end of the first LED group and the second LED group and a ground terminal, and a second switch for connecting / disconnecting the second LED And a second switch for opening / closing a connection between the terminal of the group and the ground terminal.

The LED driver may perform switching control of the first switch and the second switch according to the magnitude of the instantaneous voltage supplied by the AC power source.

Wherein the first auxiliary driver circuit includes a first optical connector and a first auxiliary switch, the first optical connector controls the first auxiliary switch to be short-circuited when the first switch is short-circuited, May be connected to the connection node between the first LED group and the second LED group and the ground node.

When the first switch is short-circuited and a current flows in the first LED group, the current flowing in the first LED group is converted into an optical signal, and the current is transferred to the first sub-driver circuit so that the first sub- The current flowing through the first LED group, which exceeds the capacity of the LED driver, may flow through the first auxiliary switch.

A first capacitor connected in parallel to the first LED group to supply a current to the first LED group during a period in which the first LED group does not receive a current from the AC power supply, And a second capacitor for supplying a current to the second LED group in a period in which the second LED group is not supplied with current from the AC power source.

The first LED group and the second LED group may be connected in series through a blocking diode that prevents current from flowing from the second LED group toward the first LED group.

The LED driver may be implemented as a single IC chip with a limitation of the output voltage.

AC power is used as the power source of LED lighting fixture, and it is possible to achieve weight reduction and miniaturization of the lighting fixture because it does not use AC / DC converter, and realize the driving circuit of LED lighting fixture with high output using AC power And reliability can be improved through a driving circuit of a relatively simple structure.

1 shows an example of a circuit configuration of an AC direct lighting type LED lighting apparatus.
2 is an example of a configuration of a high-power direct-coupled LED driving apparatus using a plurality of driving ICs.
3 and 4 show an example of the LED driver circuit structure according to the embodiment of the present invention.
5 is an example of a switching circuit configuration according to an embodiment of the present invention.
6 is an example of an auxiliary driving circuit configuration according to the embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments will be illustrated and described in detail in the drawings. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, .

In addition, the components shown in the embodiments of the present invention are shown independently to represent different characteristic functions, which does not mean that each component is composed of separate hardware or software constituent units. That is, each constituent unit is included in each constituent unit for convenience of explanation, and at least two constituent units of the constituent units may be combined to form one constituent unit, or one constituent unit may be divided into a plurality of constituent units to perform a function. The integrated embodiments and separate embodiments of the components are also included within the scope of the present invention, unless they depart from the essence of the present invention.

In addition, some of the components are not essential components to perform essential functions in the present invention, but may be optional components only to improve performance. The present invention can be implemented only with components essential for realizing the essence of the present invention, except for the components used for the performance improvement, and can be implemented by only including the essential components except the optional components used for performance improvement Are also included in the scope of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows an example of a circuit configuration of an AC direct lighting type LED lighting apparatus.

The LED light may be composed of at least one LED group and a rectifying circuit connected to the AC power source to rectify the AC power. Each LED group includes at least one LED.

In the example of Fig. 1, the diode bridge constituted by D1, D2, D3 and D4 is an example of a rectifying circuit. The diode bridge of Fig. 1 receives the AC power as a full-wave rectification circuit and outputs pulsating current. GR1, GR2, and GR3 in FIG. 1 denote LED groups, respectively, and include at least one or more LEDs. FIG. 1 shows an example of a case where the LED is composed of three LED groups GR1, GR2 and GR3, which is an embodiment only. For convenience of explanation, the LED lighting apparatus having three LED groups will be described as an example, And there is no particular limitation on the number of LED groups constituting the LED illumination.

In the example of Fig. 1, IC1 is an LED drive circuit implemented in the form of an IC package. LED driver circuits can be called various names such as LED driver, LED controller, LED driver IC, and LED driver chip. Hereinafter, these are collectively referred to as an LED driver. The LED driver may be implemented in the form of an IC chip. For convenience of explanation, the LED driver may be implemented as an IC chip. However, the present invention is not limited thereto. For example, The present invention can be applied to a method of solving the limitation of the output power of the driving circuit.

IC 1 is an LED driver that incorporates a switch with a constant current function, and each switch can be controlled on / off by various methods. In the example of FIG. 1, switches GR1, GR2, and GR3 are respectively connected to switches SW1, SW2, and SW3 for controlling the currents flowing through the respective LED groups. SW1, SW2, and SW3 may be controlled to be short-circuited in sequence according to the magnitude of each AC voltage by the switching control circuit, or may be controlled so that each switch is opened or shorted according to the magnitude of the current flowing through the switch have. And may be controlled so that the AC voltage is sequentially opened / shorted according to time after the zero crossing detection according to the embodiment.

In the example of Fig. 1, IC1 is an example of an LED driving circuit implemented by an IC. The driving circuit implemented in the IC package is subject to a certain restriction on the control power range due to the power consumption limit of the IC package. An LED driver circuit implemented in an IC package is limited to LED lighting fixtures with high output power, and generally controls output power in the range of 5 to 20W.

2 shows an example of a configuration of a high-output AC direct-coupled type LED driving apparatus to which a plurality of LED drivers are applied.

2 is compared with the example of FIG. 1 and focusing on the difference, the example of FIG. 2 is different from the example of FIG. 1 in that a plurality of LED drivers IC1 and IC2 are used. This is a method generally used in order to overcome the limit of the output power of the LED driver as described above with reference to the example of FIG. 1, in which a plurality of LED drivers are connected in parallel and used. 2 shows an example in which two LED drivers are connected in parallel and three or more LED drivers may be required depending on the output power. Multiple LED drivers can share the current flowing in a group of LEDs or connect blocks of LEDs to each LED driver in parallel.

However, in the method of using a plurality of LED drivers connected in parallel as in the example of FIG. 2, the number of LED drivers to be used increases with the increase of the output power. For example, in order to control the output of 100W, A driver may be required - a problem of increasing the implementation cost and a problem of lowering of reliability due to heat generation of the LED driver and the like.

The present invention solves the above-mentioned problems and provides an apparatus and method for controlling high output power using one LED driver.

3 shows an example of the LED driver circuit structure according to the embodiment of the present invention.

The LED lighting apparatus of FIG. 3 includes a rectifier circuit connected to an AC power source and rectifying AC power, an at least one LED group (GR1, GR2, GR3), and an LED driver IC1 as an AC direct lighting type LED lighting apparatus . 3, the LED group and the LED driver are not directly connected but are connected to each other through the auxiliary driving circuits 310, 320 and 330.

In the example of FIG. 3, IC 1 is an LED driver that is controllable for conventional low output power. In the LED lighting apparatus of FIG. 3 according to the embodiment of the present invention, the auxiliary driving circuits 310, 320, and 330 can control the high output power beyond the range of the controllable output power of the LED driver having the output power limitation .

The auxiliary driving circuits 310, 320, and 330 can limit the currents flowing through the switches SW1, SW2, and SW3 of the IC 1 so that the LED driver IC 1 can operate within a controllable range. The auxiliary driving circuit 310 can control the current flowing through the SW1 to be 20 mA or less when a conventional LED driver for controlling the output power of 5 to 20 W is applied.

As an example of the configuration, the auxiliary drive circuit may be composed of a switch circuit operating in accordance with the switching control of the LED driver and a transfer element for transmitting the switching control of the LED driver to the switch circuit of the auxiliary driver circuit. The transmitting device may be an opto-coupler, and LEDs (GaAs, GaAlAs, GaAsP) having a high light emitting efficiency and a fast response speed may be used as the light emitting device coupled to the light receiving device of the optical connector.

The auxiliary driving circuit according to the embodiment of the present invention including the transfer element and the switching circuit can be implemented in various forms including an IC chip. The auxiliary driving circuit according to the embodiment of the present invention using an optical connector and a switching circuit can increase the mounting density with a small size and light weight, and can have high reliability with a semi-permanent lifetime.

3, the switch control of SW1, SW2, and SW3 is performed by the LED driver IC 1 and the switch circuit W1 of the sub driver circuit is turned ON / OFF according to ON / OFF of the switch SW1 according to the switch control do.

The transmission element for allowing the operation of W1 to be operated according to the ON / OFF of the SW1 can convert the current flowing in the SW1 of the GR1 and the LED driver into the optical signal and transmit it to the W1. That is, when SW1 is in the ON state, the current flows to GR1 to emit the LED of GR1 and flow to SW1 through the transfer element of the auxiliary driving circuit. The transmission device senses the current flowing and transmits it to the W1 by the optical signal, and switches the W1 to the ON state. When SW1 is OFF, current flows to GR1, causing the LED of GR1 to emit and flow to GR2. In this case, no current flows through the transmission element, and therefore W1 is also switched to the OFF state. The operations of SW1 and W1 described above can be similarly applied to operations between SW2 and W2, and SW3 and W3.

The LED driving apparatus according to the embodiment of the present invention is provided with an auxiliary driving circuit and implemented in a chip form to overcome the limit of the output power of a commercially available LED driver. By using one or a relatively small number of LED drivers, it is possible to drive a high-power LED lighting fixture, thereby reducing implementation cost and increasing reliability.

4 shows another example of the LED driver circuit structure according to the embodiment of the present invention.

The circuit of FIG. 4 is characterized in that the capacitors are connected in parallel to each LED group in the circuit of FIG. Hereinafter, the detailed operation of the LED lighting controlled by the LED driving apparatus having the auxiliary driving circuit through the circuit of FIG. 4 will be described.

Switches SW1, SW2, and SW3 for controlling currents flowing through the LED groups are connected to the GR1, GR2, and GR3 through the auxiliary driving circuits 410, 420, and 430, respectively. The switches SW1, SW2 and SW3 are controlled by the switching control circuit so as to be sequentially short-circuited according to the magnitude of each AC voltage, or by detecting the current flowing through the switch, Can be controlled to be short-circuited. And may be controlled so that the AC voltage is sequentially opened / shorted according to time after the zero crossing detection according to the embodiment. D8, D9 and D10 denote the light emitting elements of the optical couplers included in the respective auxiliary driving circuits. When a current flows through SW1, SW2 and SW3 (when the corresponding switch is short-circuited) W2, and W3 to turn on / off W1, W2, and W3 according to ON / OFF of SW1, SW2, and SW3.

The operation of the circuit of FIG. 4 will be described step by step as follows.

When the VAC voltage increases and becomes larger than the threshold voltage Vfa of GR1, SW1 is short-circuited and the current of SW1 flows to GR1 and D8 of the auxiliary driving circuit 410, and the LED of GR1 emits light. D8 converts the flowing current into an optical signal and transfers it to W1 of the auxiliary driving circuit 410 so that W1 is short-circuited and the current flowing in GR1 is branched to SW1 and W1. As described above, the current flowing to SW1 at this time can be set so as not to exceed 20 mA.

When the VAC voltage further rises and becomes larger than the threshold voltage Vfb of GR1 + GR2, current flows to SW2, and the current of SW2 flows to GR1 and GR2, and the LEDs of GR1 and GR2 emit light. If SW2 is short-circuited and current flows, SW1 is opened (W1 is also opened), and if SW2 is short-circuited and current flows to D9 of the auxiliary driving circuit 420, W2 is also short-circuited.

When the VAC voltage further rises and becomes larger than the threshold voltage Vfc of GR1 + GR2 + GR3, current flows to SW3, and the current of SW3 flows to GR1, GR2 and GR3, and the LEDs of GR1, GR2 and GR3 emit light. When current flows in SW3, SW2 is opened (W2 is also open), and W3 is short-circuited.

When the VAC voltage exceeds the threshold voltage Vfc of GR1 + GR2 + GR3 beyond the peak, SW3 is opened and SW2 is short-circuited, so that the current of SW2 flows through GR1 and GR2, and the LEDs of GR1 and GR2 emit light. At this time, auxiliary driving circuit W3 is opened and W2 is shorted. W2 is short-circuited so that the current flowing to SW2 can be adjusted to be below the threshold value of the LED driver.

When the VAC voltage becomes lower than the threshold voltage Vfb of GR1 + GR2, SW2 is opened and SW1 is short-circuited, so that the current of SW1 flows through GR1, and the LED of GR1 emits light. At this time, the auxiliary driving circuit W2 is opened and W1 is short-circuited. W1 is short-circuited so that the current flowing to SW1 can be adjusted by the LED driver to the limit value or less.

When the VAC voltage becomes lower than the threshold voltage Vfa of GR1, SW1 is opened and SW1, SW2 and SW3 are both opened. At this time, no current flows through the switch SW1 regardless of whether the switch SW1 is short-circuited or not. Accordingly, in this case, the short-circuited state can be maintained without opening the switch SW1. At this time, auxiliary power of at least one of auxiliary power sources C1, C2, and C3 connected in parallel to GR1, GR2, and GR3 is operated to supply power to LED groups connected in parallel with each other, thereby emitting LEDs of the corresponding LED group.

Thereafter, when the VAC voltage rises and becomes larger than the threshold voltage Vfa of the GR1, the SW1 is short-circuited (if the SW1 is not opened and the short-circuited state is maintained as in the other embodiments described above, control for shorting the SW1 is unnecessary) The current flows to GR1, the LED of GR1 emits, and the above steps are repeated.

C1, C2, and C3, which are connected in parallel to each LED group, are turned on so that when power is not supplied to each LED group, current flows through the LED group so that the LEDs of the corresponding LED group can emit light Which is an example of an auxiliary power source.

C1, C2, and C3 are charged by the voltage across the LED group when a current flows through the LED group connected in parallel with the LED group, and when the current does not flow to the corresponding LED group, I can make it flow.

In the circuit of Fig. 4, D5 and D6 are blocking diodes for preventing reverse voltages of the auxiliary power sources C2 and C3. The number of LED groups and the number of LEDs constituting each LED group can be variously configured in consideration of power factor, luminous flux and distortion factor I _THD . The number of LEDs belonging to each LED group may be the same or different, and may be sequentially increased or decreased according to the embodiment. In order to minimize the power loss in the switch, the number of LEDs constituting each LED group Can be determined to be proportional to the AC voltage.

For example, if the number of LEDs is GR1>GR2> GR3, a relatively high luminous flux can be obtained, but power factor reduction and I _THD increase. To improve I _THD , each switch current can be set to I_SW1 = <I_SW2 = <I_SW3.

5 is an example of a switching circuit configuration according to an embodiment of the present invention.

And SW1, SW2, and SW3 are sequentially switched in accordance with the instantaneous voltage change of VAC as in the operation of the circuit of Fig. The switching circuit of Fig. 5 may be included in an LED driver and implemented.

6 is an example of an auxiliary driving circuit configuration according to the embodiment of the present invention.

When the switching control is performed by the LED driver, the switching control is transferred to the switches (e.g., W1, W2 and W3 in Figs. 3 and 4) of the auxiliary driving circuit. U1 may be implemented as an optical coupler including a transistor for emitting light and a transistor (TR) controlled by a light receiving signal. When current flows through the LED, TR of U1 turns ON, Q1 turns OFF, M1 turns ON, and current flows to the switch connected to each LED group.

R1 and R2 are bi-circuits for supplying current to the gate terminal of M1 and the base terminal of Q1 and can be clamped to the zener voltage of D1 and D2.

R3 senses the current flowing through M1 and flows a constant current through M1 through Q2. C1 bypasses the initial current of LED of U1 to C1 so that a stable optical signal can be transmitted.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (10)

In an AC power direct lighting type high power LED (Light Emitting Diode) lighting apparatus,
A rectifying circuit connected to the AC power source and configured by a bridge diode for full-wave rectification;
A first LED group composed of at least one LED supplied with current from the AC power source through the rectifying circuit;
An LED driver for controlling a current flowing in the first LED group; And
And a first auxiliary driving circuit for causing a current exceeding a capacity of the LED driver among the currents flowing through the first LED group to flow to the ground terminal without passing through the LED driver. The method according to claim 1,
A second LED group consisting of at least one LED connected in series with the first LED group and the AC power source; And
And a second auxiliary driving circuit for causing a current exceeding the capacity of the LED driver among the currents flowing in the second LED group to flow to the ground terminal without passing through the LED driver. 3. The method of claim 2,
Wherein the LED driver includes: a first switch for opening / closing a connection between a connection end of the first LED group and the second LED group and a ground terminal; And
And a second switch for opening / closing a connection between the first LED group and a terminal of the second LED group on a side opposite to the connection end of the second LED group and a ground terminal. The method of claim 3,
Wherein the LED driver performs switching control of the first switch and the second switch according to a magnitude of an instantaneous voltage supplied by the AC power source. The method of claim 3,
Wherein the first auxiliary driving circuit includes a first optical connector and a first auxiliary switch,
Wherein the first optical coupler controls the first auxiliary switch to be short-circuited when the first switch is short-
Wherein the first auxiliary switch connects the connection end of the first LED group and the second LED group to the ground. 6. The method of claim 5,
When the first switch is short-circuited and a current flows through the first LED group, the current flowing in the first LED group is converted into an optical signal, and the current is transferred to the first sub-drive circuit to short the first sub- And a current flowing in the first LED group exceeds a capacity of the LED driver through the first auxiliary switch. The method according to claim 5 or 6,
And the current flowing to the first switch is set to less than 20 mA. The method according to claim 5 or 6,
A first capacitor connected in parallel to the first LED group to supply a current to the first LED group during a period in which the first LED group is not supplied with current from the AC power supply; And
And a second capacitor connected in parallel to the second LED group to supply current to the second LED group during a period in which the second LED group is not supplied with current from the AC power supply. 9. The method of claim 8,
Wherein the first LED group and the second LED group are connected in series through a blocking diode that prevents current from flowing from the second LED group toward the first LED group. The method of claim 3,
Wherein the LED driver is implemented as a single IC chip having a limitation of an output current.

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