KR101130291B1 - LED driving device for improving stability - Google Patents

Abstract

A power efficiency correction unit for adjusting the power efficiency of the rectified voltage, a switching unit for switching the output of the power efficiency correction unit to a transformer and the output of the both ends of the transformer is rectified and synthesized and output as a square wave signal, but the balance circuit unit Disclosed is an LED driving device for balancing the current supplied to the LED channel.

Description

LED driving device for improving stability

The present invention relates to LED, and more particularly, to an LED (Light Emitting Diode) driving device with improved stability.

In general, currently widely used light emitting diodes (LEDs) are widely used for transmitting various signals or emitting light in electronic products such as home appliances, TVs, and monitors.

When the voltage applied to the LED is greater than or equal to the threshold voltage, a current starts to flow in the LED to generate light. In order to drive the LED, a low voltage DC power is supplied using a battery, a battery, or a power supply.

As a device for supplying the low voltage DC power supply described above, a power supply device is mainly used. The power supply device receives commercial AC power and converts it into a predetermined DC power supply, and converts it into a LED driving power and supplies it to the LED. do.

At this time, the power supply for driving the LED is controlled according to the dimming (Dimming) signal from the outside and the brightness of the LED can be adjusted accordingly.

Meanwhile, in order to drive a plurality of channels using the above-described conventional power supply device, a constant current circuit using a transistor, a boost circuit, and the like are used, but when a deviation between channels occurs, a problem of efficiency may occur or a circuit may be improved. There is a problem that becomes complicated.

In addition, conventionally, when one or more LED failures occur in a channel in which a plurality of LEDs are connected in series, efficiency is reduced to overcome this.

1 and 2 show a LED driving method according to the prior art.

1 is a diagram of a driving method having a plurality of channels (multiple LED series connection modules or less channels) according to the prior art, and a method of driving a plurality of channels in parallel by connecting a plurality of channels to an output of a DC circuit or a BOOST circuit. . It has a constant current method in which a transistor and a resistor are connected to the rear of each channel. However, when the deviation of each channel occurs, the current is adjusted by changing the resistance of the transistor. However, this poses a problem for efficiency because it is, after all, like a resistive load.

2 is also an exemplary road driving method having a plurality of channels according to the prior art, a method of adding a boost circuit for each channel. Using this method, a boost circuit is used for each channel, and current can be matched without a constant current circuit using a transistor or the like. However, the LED driving method of FIG. 2 has a loss in the process of boosting the direct current back to the boost circuit, and there is a problem in that the circuit is complicated because a boost circuit such as the number of channels is used.

like this. As shown in FIG. 1 or FIG. 2, when driving a high voltage or a plurality of channels, a problem of the complexity and stability of the circuit occurs in the conventional methods.

The technical problem to be achieved by the present invention is to solve the conventional problems by directly driving the LED of the secondary power stage using the primary power source, by providing an LED driving device to improve the stability, simplifying the circuit and efficiency To increase.

LED driving device according to a feature of the present invention for solving this problem,

An LED unit including a plurality of LED channels;

Rectifying unit for receiving rectified AC power;

A switching unit for switching the rectified power according to an external control signal;

A transformer for converting the power applied according to the switching of the switching unit according to a predetermined turns ratio and outputting the power to both ends;

A synthesizer for rectifying, synthesizing and outputting currents at both ends output from the transformer;

A balance circuit unit which receives the output of the synthesis unit and supplies a constant current to the LED unit;

A control unit for controlling the switching unit so that the current supplied to the LED unit is fed back and the current supplied to the LED unit is constant;

The balance circuit unit,

Each LED channel has a primary coil connected in series to an input terminal, and a secondary coil electromagnetically connected to the primary coil, and the secondary coil is connected to a secondary coil connected to different channels to provide a closed loop. It is characterized by forming.

LED driving device according to another feature of the present invention for solving this problem,

An LED unit including at least one light emitting element;

Rectifying unit for receiving rectified AC power;

A switching unit for switching the rectified power according to an external control signal;

A transformer for converting the power applied according to the switching of the switching unit according to a predetermined turns ratio and outputting the power to both ends;

A synthesizing unit configured to drive the LED by rectifying and synthesizing the currents at both ends output from the transformer;

A balance circuit unit connected to a rear end of the LED unit and configured to supply a constant current to the LED unit;

A control unit for controlling the switching unit so that the current supplied to the LED unit is fed back and the current supplied to the LED unit is constant;

The balance circuit unit has a primary coil connected in series to an output terminal of the LED channel, a secondary coil electromagnetically connected to the primary coil, and the secondary coil is connected to a secondary coil connected to different channels. It is characterized by connecting to each other to form a Peruvian.

The switching unit switches primary power using various (Half OR Full Bridge, Push-pull, etc.) topologies, and transfers the switched power to the primary coil of the transformer for driving the LED.

The output of the transformer is output from the secondary coil in accordance with the power supply waveform of the primary coil side, which is the output of the switching unit, rectified to the + power in the rectifier circuit to drive the LED, and the switching supplied to the primary coil The output is changed according to a negative switching waveform.

In addition, the output of the transformer may be added to the Vpeak reduction circuit, the current balance circuit and the like between the LED, it is characterized in that the DC smoothing circuit, such as the existing electric cap, the boost circuit is omitted.

The control unit controls the secondary output of the transformer for directly driving the LED by controlling the switching unit on the transformer primary side by receiving the output current of the LED unit feedback.

LED driving device according to another feature of the present invention for solving this problem,

An LED driving device having a plurality of LED channels, LED power supply for driving a plurality of LED channels,

It includes a balance circuit for allowing a constant supply of current to the plurality of LED CHANNEL,

Each of the plurality of LED channels,

At least one LED is connected in series to make one LED channel, drive current,

The LED balance circuit unit,

And a primary coil connected in series to an input terminal or an output terminal of the LED channel, and a secondary coil electromagnetically connected to the primary coil, wherein the secondary coil is connected to a secondary coil connected to different channels. To form at least one closed loop,

The closed loop is characterized by matching the current balance between each loop by using a 1: 1 balance coil between each other.

According to the embodiment of the present invention, by driving a plurality of LED channels using a balance circuit, it is possible to provide an LED driving device that ensures stability such as parallel driving current balance.

In addition, by using the current balance circuit, in the problem caused by the LED failure as well as the current balance caused by the current compensation by the deviation of each LED, depending on the compensating ability of the balance circuit until a few LEDs are dead dead. By compensating for the current deviation, overcurrent protection as well as protection of the LED by overcurrent and continuous operation of the LED are possible without additional configuration of additional circuitry.

This provides a stable circuit that can generate heat, current balance, continuous driving, etc. before the operation of the PROTECTION circuit, and in addition to the characteristics of the balance circuit, it greatly improves the reliability of the product.

In addition, compared to the conventional method, it is possible to obtain an effect of simplifying a circuit and increasing efficiency in driving a high voltage, a high current, and a plurality of channels.

In addition, by providing a driving device for directly driving the LED by using an insulation transformer, since no direct current (DC) conversion is performed, efficiency can be increased.

In addition, due to the provision of the control unit, the direct drive of the LED using an isolation transformer driven by various switching topologies (SWITCHING TOPOLOGY, Half OR Full Bridge, Push-pull, Flyback, Forward, etc.) is possible to improve efficiency and simplify the circuit. It becomes possible. In addition, since the output can be variously designed using a control unit frequency, duty, PFC voltage change, etc., there is an advantage that the design becomes easy.

1 or 2 is an exemplary view showing a conventional LED driving method.
3 is a configuration diagram showing an LED driving device with improved stability according to the first embodiment of the present invention.
4 is a configuration diagram illustrating an LED driving device having improved stability according to a second exemplary embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

3 is a configuration diagram of the LED driving apparatus according to the first embodiment of the present invention.

Referring to FIG. 3, in the first embodiment of the present invention, the AC input unit 100, the AC rectifier 200 (including DC), the power efficiency correcting unit 300, the switching unit 400, the transformer 500, and the controller 600, a synthesis unit 700, an LED unit 800, and a balance circuit unit 900.

In the block diagram of FIG. 3, the internal circuit components are only schematic illustrations for explanation, not actual connection relationships, and other components are additionally connected, and the detailed configuration is not shown because the internal configuration of the block is well known in the art. Did.

The LED unit 800 includes a plurality of LEDs 810 to 840 therein and emits light according to the supply of current. The current supplied to the LED is fed back to the controller 600 through elements such as transistors and resistors (not shown).

The controller 600 receives the current from the LED unit 800 and controls the current supplied to the LED unit 800 to be constant.

The rectifier 200 receives the AC AC power supply 100 and rectifies the rectifier 200.

The power efficiency corrector 300 adjusts the power efficiency of the power rectified by the rectifier 200 according to the control signal of the controller 600, and may be omitted as necessary.

The switching unit 400 switches the output power of the power efficiency correcting unit 300 according to the control signal of the control unit 600. When there is no power efficiency correcting unit 300, the switching unit 400 outputs the output signal of the rectifying unit 200. Switch.

The transformer 500 converts the power applied according to the switching of the switching unit 400 according to a predetermined turns ratio and outputs the outputs at both ends. A partial output waveform is schematically illustrated in FIG. 3.

The synthesizer 700 rectifies, synthesizes, and outputs currents at both ends output from the transformer using diodes 710 and 720, respectively.

The balance circuit unit 900 has a primary coil connected in series to an input terminal of the LED channel, and has a secondary coil electrically connected to the primary coil, and the secondary coil of the balance coil is connected to different channels. It is connected to the secondary coil of the balance coil to form a loop to compensate for the current deviation, thereby balancing the current.

The balance circuit unit 900 has a primary coil and a secondary coil, but if necessary, the winding portion of the primary coil may have N windings, and each of the N primary coil windings is in series with the LED channel. The balanced current can be sent to the secondary coil which is connected to form a bellows.

The balance for the balance can be separated into several loops as necessary, and the current balance between each loop can be adjusted by connecting a specific loop or all loops using a 1: 1 balance coil.

3 is a representative example diagram, and according to the shape of the balance coil, a circuit may be modified or simplified in driving a plurality of LED channels using a primary coil, a secondary coil to an N-order coil, and the like.

In the embodiment of the present invention, the booster circuit, various additional circuits, and the like are omitted, thereby simplifying the circuit and significantly reducing the manufacturing cost.

The switching unit 400 switches primary power using various (Half OR Full Bridge, Push-pull, etc.) topologies as necessary, and transfers the switched power to the primary coil of the transformer for driving the LED.

The output of the transformer 500 outputs from the secondary coil according to the power supply waveform of the primary coil side, which is the output of the switching unit 400, and rectifies it to + power in the rectifier circuit to drive the LED, 1 The output is changed according to the switching waveform of the switching unit 400 supplied to the difference coil.

In addition, the output of the transformer 500 may be added to the Vpeak reduction circuit and the like between the LED, it is characterized in that the DC smoothing circuit, such as the existing electric cap, the boost circuit is omitted.

The control unit 600 controls the secondary output of the transformer for directly driving the LED by controlling the switching unit of the transformer primary side by receiving the feedback of the output current of the LED unit.

The operation of the LED driving apparatus according to the first embodiment is as follows.

Referring to FIG. 3, the AC power is input from the AC input unit 100 and converted into DC through the AC rectifying unit 200.

Then, the power efficiency correction unit 300 is output at a predetermined voltage.

The switching unit 400 switches in a switching method using a half or a full bridge, and switches the primary PFC output voltage under the control of the controller 600.

If necessary, the controller 600 may control the switching unit 400 or the power efficiency calibration unit 300 to obtain a desired output voltage.

Then, the output voltage of the switching unit 400 generates an induced current according to a predetermined turns ratio through the insulating transformer 500 for driving the LED. Here, the switching signal is output to both ends of the insulating transformer 500 according to the output signal of the switching unit 400, the two outputs are respectively rectified by the diodes (710, 720) of the synthesis unit 700 and then one + Synthesized by + Power signal.

Then, the balance circuit 900 supplies the output signal to each channel 810 ˜ 840 of the LED unit 800 in parallel, and is balanced by the induction action of the primary coil and the secondary coil. Here, the current flowing in the LED channels 810 to 840 is induced to the secondary coil electromagnetically coupled with the primary coil, and the induced current is connected to the secondary side of the peripheral balance coil so as to flow through the Peruf. The current balance is compensated for by the current deviation.

In the first embodiment of the present invention, the LED unit 800 is directly driven by the output voltage of the transformer 500, and the LED is directly driven without going through an electric cap or a boost circuit as in the prior art. Therefore, the circuit can be simplified.

3, the control unit 600 receives a driving current from the LED unit 800 and generates a switching signal and a control signal PFC CONTROL to control an input signal of the transformer 500. This makes it possible to control the output of the transformer 500 that directly drives the LED.

The control unit 600 of FIG. 3 is merely an example for direct LED driving, and the topology of the switching unit 400 (Half OR Full Bridge, Push-pull, Flyback, Forward, etc.) or a control method of the control unit 600 may be necessary. It is possible to modify accordingly. In addition, the power efficiency calibration unit 300 may be omitted if necessary, and in some cases, an additional circuit for reducing current balance or Vpeak may be added. In addition, the function of the controller may be added or reduced depending on the topology, additional circuits, and the like.

The control unit 600 controls the output of the insulation transformer 500 for directly driving the LED by controlling the switching unit 400 of the primary side by receiving the driving signal of the LED unit 800 on the secondary side of the transformer 500. Done.

The feedback input FEEDBACK of the integrated circuit is an LED driving current, and the controller 600 receives peak and RMS of the LED driving current.

The control unit according to the embodiment of the present invention may add an output control function in various ways as needed, and the control method may selectively use one function of frequency control, duty control, PFC control, or add all functions. It may be.

The configuration of this first embodiment can be variously modified.

One example of such a modification will be described with reference to FIG. 4.

4 is a configuration diagram illustrating an LED driving device having improved stability according to a second exemplary embodiment of the present invention.

Referring to FIG. 4, in the second embodiment, the position of the balance circuit unit 910 is modified to the rear end of the LED unit 800 in the first embodiment, and the detailed description is omitted since the remaining parts are the same and the same in operation.

Due to the provision of such an LED drive device, in the problem caused by LED failure as well as the current balance caused by current compensation due to the deviation of each LED, according to the compensating ability of the balance circuit until a few LEDs are dead dead. By compensating for the current deviation, overcurrent protection as well as protection of the LED by overcurrent and continuous operation of the LED are possible without additional configuration of additional circuitry.

This provides a stable circuit that can generate heat, current balance, continuous driving, etc. before the operation of the PROTECTION circuit, and in addition to the characteristics of the balance circuit, it greatly improves the reliability of the product.

In addition, compared to the conventional method, it is possible to obtain an effect of simplifying a circuit and increasing efficiency in driving a high voltage, a high current, and a plurality of channels.

In addition, in the embodiment of the present invention, by providing the integrated circuit for directly driving the LED by using the isolation transformer by controlling the output voltage of the first power efficiency correction unit, since the direct current (DC) conversion is not performed, the efficiency can be increased. .

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (6)

An LED unit including a plurality of LED channels;
Rectifying unit for receiving rectified AC power;
A switching unit for switching the rectified power according to an external control signal;
A transformer for converting the power applied according to the switching of the switching unit according to a predetermined turns ratio and outputting the power to both ends;
A synthesizer for rectifying, synthesizing and outputting currents at both ends output from the transformer;
A balance circuit unit which receives the output of the synthesis unit and supplies a constant current to the LED unit;
A control unit for controlling the switching unit so that the current supplied to the LED unit is fed back and the current supplied to the LED unit is constant;
The balance circuit unit,
Each LED channel has a primary coil connected in series to an input terminal, and a secondary coil electromagnetically connected to the primary coil, and the secondary coil is connected to a secondary coil connected to different channels to provide a closed loop. Forming,
The synthesizing unit includes a first and a second diode for rectifying the power of both ends output from the transformer, and the LED driving device, characterized in that for synthesizing the output of the first and second diodes. An LED unit including at least one light emitting element;
Rectifying unit for receiving rectified AC power;
A switching unit for switching the rectified power according to an external control signal;
A transformer for converting the power applied according to the switching of the switching unit according to a predetermined turns ratio and outputting the power to both ends;
A synthesizing unit configured to drive the LED by rectifying and synthesizing the currents at both ends output from the transformer;
A balance circuit unit connected to a rear end of the LED unit and configured to supply a constant current to the LED unit;
A control unit for controlling the switching unit so that the current supplied to the LED unit is fed back and the current supplied to the LED unit is constant;
The balance circuit unit has a primary coil connected in series to an output terminal of the LED channel, a secondary coil electromagnetically connected to the primary coil, and the secondary coil is connected to a secondary coil connected to different channels. Connected to each other to form a Peruvian,
The synthesizing unit includes a first and a second diode for rectifying the power of both ends output from the transformer, and the LED driving device, characterized in that for synthesizing the output of the first and second diodes.

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