KR102488053B1 - Control system for parallel connected led modules - Google Patents

Abstract

The present invention comprises a control system of parallel connected LED modules, which comprises: a plurality of LED modules (300) connected in parallel; a converter (100) that supplies power to the plurality of LED modules (300); and a monitoring part (200) that detects a short circuit of the LED module (300) and outputs a detection signal to the converter (100), wherein the monitoring part (200) outputs a voltage proportional to a number of short-circuited LED modules (300) within a voltage range set at an input terminal (Vin) of the converter (100). Therefore, the present invention is capable of prolonging a lifespan of an LED.

Description

Control system of LED modules connected in parallel {CONTROL SYSTEM FOR PARALLEL CONNECTED LED MODULES}

The present invention relates to a control system for LED modules connected in parallel.

In general, an LED device has an excellent energy saving effect, can be used semi-permanently with a long lifespan, is eco-friendly, and has a high-speed response, so it is in the limelight as a next-generation light source.

Recently, as the problem of low luminance of the LED device has been greatly improved, the application field is expanding throughout the industry, such as a light source for a backlight of an LCD panel or a lighting device.

The LED element is a semiconductor element that emits light when a forward voltage is applied. The light output of the LED device is determined by the forward current, and as can be seen from the current-voltage characteristic curve of the LED, a very large change in forward current is represented by a small change in forward voltage (Vf).

Therefore, in order to emit light of a plurality of LED elements with uniform brightness, a driving circuit including a PWM circuit (Pulse Width Modulation) is used, and the LEDs are controlled by the pulse width modulation method.

Conventionally, various technologies have been proposed to control the current of lighting fixtures to which such LEDs are applied, and in particular, the current is controlled through PWM control in a structure in which LED modules in which a plurality of LEDs are connected in series are connected in parallel.

However, such a lighting system in which LED modules are connected in parallel must have an MCU in order to monitor the voltage of the resistor.

However, since MCU is vulnerable to noise compared to passive elements, it is vulnerable to external falling and surrounding transformer noise, so there is a high possibility of malfunction, and since a program must be written for each IC during production, the unit price rises due to the increase in work man-hours due to the additional work process.

In addition, in the prior art, when the LED module is unconnected, the dimming signal is off, and at least one LED module is connected, the MCU receives a current flowing commonly to the LED module and controls to stop the operation of the LED module. generate a signal Such prior art is as shown in FIG. 1 .

1 is a diagram showing the prior art.

Referring to Figure 1, the prior art includes an LED module connected in parallel, a current sensor unit and a control unit.

A plurality of LED modules are connected in parallel, and each LED module includes a plurality of LEDs connected in series.

The current sensor unit is composed of an operational amplifier and senses the current from the output side of the LED module.

Since this prior art constitutes a circuit in which each operational amplifier is connected between the resistor and the output side of the LED module, for example, when a current of 550mA is supplied for 25W lighting, the minimum voltage for current monitoring is about Since it should be around 1V, a loss (for example, when a current of 550mA flows, about 0.6W loss) may occur as a resistance of about 2ohm is required on the output side of each LED module.

Therefore, when monitoring four 25W LED modules with a capacity of 100W, a total power loss of 2.4W occurs as each loss of 0.6W occurs.

That is, the conventional parallel-connected LED module monitoring device requires an expensive semiconductor such as an MCU, and has a problem in that power loss is large due to the installation of a resistor for current monitoring.

In addition, in a system for controlling an LED lighting fixture by applying such a conventional PWM method, when PWM control is performed from a constant current source, current does not flow from the source source during off-time, so the voltage value of the source source rises to the maximum. Then, overshoot occurs due to circuit operation delay characteristics during the time from the maximum voltage point to the constant current point when the switch is turned on.

Therefore, in the conventional technology for controlling LED lighting fixtures through PWM-type current control, overshoot current exceeding the LED rated current continues to occur during PWM control in a situation where some of the LED modules are short-circuited and not operated, resulting in LED There is a problem of shortening the lifespan by continuously giving damage to.

KR 10-1753193 B1(2017.06.27)

The present invention has been made to solve the above conventional problems, and an object of the present invention is low manufacturing cost, and can be controlled without damaging the remaining normal LED modules due to a failure of some of a plurality of LED modules. It is to provide a control system of LED modules connected in parallel.

Therefore, the present invention includes the following embodiments in order to achieve the above object.

An embodiment of the present invention includes a plurality of LED modules connected in parallel, a converter for supplying power to the plurality of LED modules, and a monitoring unit for detecting a short circuit of the LED module and outputting a detection signal to the converter, and the detection signal of the monitoring unit is a converter. It is a voltage proportional to the number of short-circuited LED modules within the voltage range set at the input terminal of, and the converter adjusts the level of power output to the plurality of LED modules according to the voltage level of the detection signal input from the monitoring unit. It provides a control system for LED modules connected in parallel.

Therefore, the present invention does not use expensive components as a configuration capable of detecting disconnection of each module, and continuously damages the LED by adjusting the level of the analog detection signal according to the number of short circuits rather than the PWM control method. It does not occur, so the lifespan can be extended compared to the existing ones.

1 is a circuit diagram showing the prior art.
2 is a block diagram illustrating the present invention.
3 is a block diagram showing a monitoring unit of the present invention.
4 is a circuit diagram showing the sensing means of the present invention.
5 is a circuit diagram schematically illustrating an embodiment of the present invention.
6 is a circuit diagram schematically illustrating another embodiment of the present invention.
7 is a schematic circuit diagram showing still another embodiment of the present invention.
8 is a circuit diagram schematically illustrating another embodiment of the present invention.

Although the present invention may have various changes and various embodiments, it will be described in detail by exemplifying specific embodiments in the drawings. This is not intended to limit the present invention to specific embodiments, and to any one of all modifications, equivalents or substitutes included in the spirit and scope of the present invention for connecting and/or fixing structures extending in different directions. It should be understood as applicable.

Terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as "include" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, a preferred embodiment of a control system of parallel connected LED modules according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a block diagram showing the present invention, Figure 3 is a block diagram showing a monitoring unit of the present invention.

Referring to FIGS. 2 and 3 , the present invention includes a converter 100 for supplying power and controlling on/off, a plurality of LED modules 300, and a monitoring unit 200.

The converter 100 supplies power to the LED module, adjusts the level of power according to the short-circuit detection signal of the LED modules from the monitoring unit 200, and outputs the power to the LED module. For example, the converter 100 outputs a dimming input terminal (Vin) to which an input voltage (eg, 0 to 10V) set for dimming control of the LED module is input, and driving power of the LED module. It includes an output terminal (Iout). Here, the dimming input terminal Vin is connected to the monitoring unit 200 .

Accordingly, the converter 100 receives the short circuit detection signal from the monitoring unit 200 within a set input voltage range (eg, 0 to 10V). Therefore, the converter 100 can detect whether or not the number of LED modules 300 are short-circuited according to the level of the received voltage, and adjusts the level of power output to the LED modules 300 according to the result.

That is, the converter 100, for example, converts the power output during normal operation of a total of four LED modules (310, 320, 330, 340) to driving the three LED modules when one LED module is short-circuited. It can be supplied by adjusting the power supply, so unnecessary waste of energy can be prevented.

In the LED module 300, a plurality of LEDs are connected in series to form a group, and each LED module 300 is connected in parallel with each other. That is, a plurality of LED modules 300 are connected in parallel.

The monitoring unit 200 monitors whether the LED modules 300 are short-circuited. Here, the monitoring unit 200 does not apply a computational semiconductor such as MCU, and detects whether a short circuit is present by combining analog circuit elements, and the voltage adjusted within the range of the voltage set at the input terminal of the converter in proportion to the number of short circuits. outputs a short-circuit detection signal.

That is, the short-circuit detection signal of the monitoring unit 200 is a value proportional to the number of short-circuited LED groups within the set input voltage range of the converter.

A description of the monitoring unit 200 will be described below.

Figure 3 is a block diagram showing the monitoring unit of the present invention, Figure 4 is a circuit diagram showing the sensing means 210 of the present invention, Figure 5 is a circuit diagram showing a simplified embodiment of the present invention.

3 to 5, in the present invention, the monitoring unit 200 includes a sensing means 210 for detecting a short circuit of the LED module 300 and converting and outputting an output signal of the sensing means 210 into a constant current. It includes a constant current output means 220, a reference power source 230 for outputting a reference voltage, and a detection signal output means 240 for outputting the voltage across both ends of the constant current output means 220 to the converter 100. .

The sensing means 210 detects short circuits of each different LED module 300 as a plurality. For example, the sensing unit 210 may detect whether or not a short circuit is present by comparing the reference voltage Vref and the forward voltage Vf of the LED module 300 .

That is, the sensing means 210 is a comparator composed of an inverting terminal (-) and a non-inverting terminal (+), and receives the forward voltage (Vf) of the LED module 300 connected to the inverting terminal (-), and The inverting terminal (+) compares the reference voltage (Vref) output from the reference power supply 230 and outputs a High signal if it matches the set reference range, and a Low signal if it does not match.

The constant current output means 220 is connected to the output side of the sensing means 210, respectively, and outputs a constant current.

Here, the constant current output means 220 are serially connected to the output side of the sensing means 210 and connected in parallel with other constant current output means 220 . Accordingly, the constant current output unit 220 outputs a constant current within a range set according to High or Low in the sensing unit 210 .

For example, the constant current output means 220 has an input terminal connected to the output terminal of the sensing means 210, a first output terminal to the detection signal output means 240, and a second output terminal to the output terminal of the sensing means 210, respectively. It may be composed of a switching element to be connected.

The switching element outputs a constant current while being turned on or off according to the output signal of the sensing unit 210 .

Here, the plurality of constant current output means 220 form a mutually parallel structure as the first output terminal is connected to the detection signal output means 240 respectively. Therefore, the voltage applied to both ends of the plurality of constant current output means 220 is the same.

In addition, the voltage applied to both ends of the plurality of constant current output means 220 is proportional to the number outputting Low from all the sensing means 210. For example, the voltage across both ends of the constant current output means 220 is reduced by 20% compared to the maximum value output at 100% High when Low is output at 20% from all detection means 210. .

The detection signal output means 240 calculates the difference between the voltage applied to both ends of the constant current output means 220 connected in parallel and the input reference voltage and outputs it to the converter 100. At this time, the detection signal output means 240 is a differential subtraction circuit using an OP AMP, and the reference voltage is preferably set to 0V. That is, the detection signal output means 240 outputs a voltage across both ends of the constant current output means 220 connected in parallel.

Here, the voltage at the time of 100% output of the detection signal output means 240 is set, and the total output value is reduced in proportion to the number of short-circuited modules among all modules and outputted. This total output value may be in the same range as the voltage across both ends of the constant current output means 220 .

For example, the sensing means 210 is the first LED module 310, the second LED module 320, the third LED module 330, the final LED (D11) of the fourth LED module 340 and its It is connected between the LEDs (D12) in the next order, respectively, and detects the forward voltage (Vf) of each module (310, 320, 330, 340) and outputs a High or Low signal.

Here, the detection signal output to the converter according to the short-circuit ratio among all LED modules (eg, 4 modules) may output a voltage reduced according to the short-circuit ratio from the maximum value of the input voltage of the set converter.

From this configuration, the present invention can detect the short circuit of the LED module 300 in more various ways.

As an embodiment, the present invention can detect whether or not a short circuit occurs through the forward voltage of the LED module 300 as described above. For example, in the LED module 300, a plurality of LEDs are connected in series and connected between the input side of the first LED (D11) installed at the final position of the output side and the output side of the second LED (D12) in the next order. A short circuit may be detected by sensing the forward voltage Vf of the LED module 300 .

And the detection signal output means 240 reduces and outputs the set voltage in proportion to the shorted number.

Therefore, the converter 100 checks the voltage level of the detection signal input from the detection signal output unit 240 and adjusts the power level supplied to the LED module 300 to prevent damage to the LED.

In addition, in another embodiment of the present invention, in one embodiment of detecting short circuit by forward voltage (Vf) of the LED module 300, when a short circuit is detected between the output terminal of the final LED and the ground terminal, it can be detected as a short circuit. Other embodiments configured without it may be further included.

Another embodiment is described with reference to FIG. 6 .

6 is a circuit diagram showing another embodiment of the present invention.

Referring to FIG. 6, in another embodiment of the present invention, an LED module to which a plurality of LEDs are connected in series, a detection means 210 for detecting a short circuit of the LED module, and a short circuit detection of a ground end connected to the last LED of the LED group. means (ZD1).

In the LED module 300, a plurality of LEDs D11, D12, D13, and D14 are sequentially connected in series. Here, the first LED (D11) is the farthest from the input side, and corresponds to the last LED whose output terminal is connected to the ground terminal. In addition, the second LED (D12) corresponds to the next LED connected to the input terminal of the first LED (D11).

The sensing means 210 is connected between the last LED D11 and the next LED D12.

The short circuit detecting means (ZD1) has an input terminal connected to the output side of the last LED (D11), and an output terminal connected between the input side of the last LED (D11) and the output side of the next LED (D12). Preferably, the short-circuit detection means ZD1 of the ground terminal may include a Zener diode.

As such, in another embodiment, when a short circuit occurs between the ground terminals on the output side of the final LED (D11), the voltage output from the output terminal of the final LED (D11) is input to the input terminal of the short circuit detection means (ZD1), and the sensing means (210) ) outputs a voltage higher than the normal value.

That is, in another embodiment, when a short circuit occurs between the output terminal of the final LED D11 and the ground terminal, a Zener diode is applied to detect the occurrence.

In addition, the present invention can detect whether or not a short circuit is present using a resistor. Another such embodiment will be described with reference to FIG. 7 .

7 is a simplified circuit diagram showing another embodiment of the present invention.

Referring to Figure 7, in another embodiment of the present invention, the LED module 300 is connected in series to the first LED (D11) installed in the final position located on the output side, the second LED (D12), the third LED (D13) ) is connected in series to the second LED (D12) and the fourth LED (D14) to the third LED (D13). Here, the output terminal of the first LED (D11) is connected to the ground terminal.

In addition, in another embodiment, a short circuit detection resistor R11 is installed between the first LED D11 and the ground terminal, and the sensing means 210 detects the voltage Vs across the short circuit detection resistor R11. connected to do

That is, another embodiment of the present invention is connected in various ways at the output side of the LED module 300 to detect a short circuit, and detects within the set input voltage range of the converter 100 according to the number of shorted LED modules 300. It is characterized in that the level of the signal is adjusted.

8 is a simplified circuit diagram showing another embodiment of the present invention.

Referring to FIG. 8 , another embodiment of the present invention has an arrangement structure opposite to that of the embodiment of FIG. 7 . For example, in another embodiment, the second LED (D12) is connected in series to the input side of the first LED (D11), the output side of which is installed in the final position located on the output side, is connected to the ground terminal, and the third LED (D13) is In the LED module 300 in which the second LED (D12) and the fourth LED (D14) are connected in series to the third LED (D13), a short circuit detection resistor (R12) is connected to the input side of the fourth LED (D14) corresponding to the starting stage. is installed, and the sensing means 210 is connected to sense the voltage Vs across the short-circuit sensing resistor R12.

That is, the present invention can detect a short circuit on the input side or output side of the LED module 300, and adjusts the level of the detection signal within the set input voltage range of the converter 100 according to the number of shorted LED modules 300 characterized by

The operation and effects of the present invention will be described. Here, the present invention will be described through another embodiment in which a short-circuit detection means made of a Zener diode is provided.

For example, the first to fourth LED modules 310, 320, 330, and 340 are not short-circuited. The forward voltage (Vf) of each LED module 300 is the same as, for example, 3.8V, and all the sensing means 210 output High. Therefore, the voltage applied to both ends of the constant current output means 220 is a voltage corresponding to 100% (eg, 10V) within the set input voltage range (0 to 10V).

Therefore, the detection signal output unit 240 outputs a voltage of 10V to the converter 100 .

In addition, the present invention can perform the following operation when detecting whether a total of four LED modules 300 are short-circuited.

For example, two LED modules (eg, a first LED module 310, a second LED module, a third LED module 330, and a fourth LED module) among a total of four LED modules (eg, When a short circuit occurs between the first LED module 310 and the fourth LED module, the sensing unit 210 connected to the first LED module and the fourth LED module 310 and 340 outputs a low signal. .

On the other hand, a high signal is output from the sensing unit 210 connected to the second LED module 320 and the third LED module 330 that are not short-circuited. In addition, the constant current output means 220 are all constant current output means according to each signal of the detection means 210 for outputting a short circuit detection signal and the detection means 210 for outputting a non-short circuit detection signal as they are connected in parallel with each other. The voltage across both ends of 220 becomes a voltage reduced by 50% (eg, 5V) in the range of the set input voltage.

In addition, three LED modules (eg, the first LED module 310, the second LED module, the third LED module 330, and the fourth LED module) of the total four LED modules (eg, the first LED module 310) A short circuit occurred in the LED module 310, the third LED module 330, and the fourth LED module 340.

Then, when all four LED modules 310, 320, 330, and 340 are in normal operation, the voltage input to the input terminal Vin of the converter 100 is the maximum value (eg, 10V), and the short circuit is detected. It is reduced from the maximum value in proportion to the number of LED modules 300.

That is, in the present invention, when only 50% of the entire LED module 300 is operated, a voltage reduced by 50% from the maximum value of the input terminal Vin of the converter 100 is input, and 25% of the entire LED module 300 When operated only, a voltage corresponding to 25% of the maximum value of the input voltage of the converter 100 is output.

In view of this, the present invention can produce more accurate sensing results without using an expensive device such as an MCU, unlike the conventional method of controlling LED groups connected in parallel through a PWM control method.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and is common in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Of course, various modifications and implementations are possible by those with knowledge of, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

100: converter
200: monitoring unit
210: detection means
220: constant current output means
230: reference power
240: detection signal output means
300: LED module
ZD1: short circuit detection means

Claims (5)

A plurality of LED modules 300 connected in parallel;
Converter 100 for supplying power to a plurality of LED modules 300; and
A monitoring unit 200 for detecting a short circuit of the LED module 300 and outputting a detection signal to the converter 100; including,
The detection signal of the monitoring unit 200 is a voltage proportional to the number of short-circuited LED modules 300 within the voltage range set at the input terminal Vin of the converter 100,
The converter 100 is
Adjusting the level of power output to the plurality of LED modules 300 according to the voltage level of the detection signal input from the monitoring unit 200; Control system of parallel connected LED modules characterized by.
The method according to claim 1, the monitoring unit 200
Sensing means 210 for detecting forward voltages (Vf) of different LED modules 300 as a plurality connected to each LED module 300, respectively, and comparing them with the reference power source 230;
Constant current output means 220 for converting and outputting the output of the sensing means 210 into a constant current as a plurality connected to each sensing means 210;
a detection signal output means 240 for outputting a voltage across the constant current output means 220 to the converter 100; including,
The constant current output means 220 are connected in parallel with each other; Control system of parallel connected LED modules characterized by.
The method according to claim 2, the sensing means (210)
Control system of parallel connected LED modules, characterized in that the comparator (Comparator).
The method according to claim 2, the sensing means (210)
A Zener diode connected in parallel with any one of the LEDs connected in series for each LED module 300; A control system of LED modules connected in parallel further comprising a.
The method according to claim 2, the sensing means (210)
A sensing resistor installed in the power line connected to the output terminal of the final LED in the LED module 300; Parallel-connected LED module control system comprising a.

Images