WO2014061866A1

WO2014061866A1 - Led lighting device for protecting service life of led elements and method for controlling same

Info

Publication number: WO2014061866A1
Application number: PCT/KR2012/011436
Authority: WO
Inventors: 조병옥
Original assignee: 주식회사 이엠퍼스트
Priority date: 2012-10-17
Filing date: 2012-12-26
Publication date: 2014-04-24

Abstract

Disclosed is an LED lighting device comprising: an LED module in which a plurality of LED arrays having a plurality of LED elements connected in series are connected in parallel; a constant current supply unit for applying a constant current to the LED module; variable resistance units which are connected to the respective LED arrays in series; and a control unit for controlling the constant current supply unit and the variable resistance units, wherein the control unit matches the entire resistance of the respective LED arrays by adjusting the variable resistance units when at least one from among the measured current values of the respective LED arrays is deviated from a normal range such that the current balance can be maintained.

Description

LED lighting device to protect the service life of the LED device and its control method

The present invention relates to an LED lighting device.

In general, in a lighting device using a light emitting diode (LED), a plurality of LEDs are connected in series to form an LED array, and the plurality of LED arrays are connected in parallel to form an LED module.

When the LED arrays in which a plurality of LEDs are connected in series are driven in a state where a plurality of LEDs are connected in parallel, the operating voltage (Vf) of the LED elements changes as the operation time increases, so that the current balance of the LED arrays connected in parallel Will be broken.

That is, when an error occurs in the LED device, the LED array including the LED device increases the operating voltage (Vf) of the LED device so that a current less than the normal current flows, or the operating voltage (Vf) of the LED device decreases, thereby causing the normal current. Greater current flows. However, since the set current of the constant current generator does not change, the changed current in the deteriorated LED array causes the current to increase or decrease in other LED arrays that do not deteriorate.

As a result, the current balance of the LED array is broken, and thus the brightness of the LED array is changed by the LED array as a whole, so that uniform brightness cannot be maintained. In addition, when the current increases in a specific LED array, there is a problem that the LED life is shortened.

Therefore, in order to solve such a problem, Korean Patent Publication No. 2009-0011744 provides a constant current circuit in each LED array to drive a constant current to drive an LED driving circuit for controlling an unbalance of current flowing through the LED unit. It is starting furnace.

However, the LED driving circuit can prevent the lifespan of the LED from being shortened by blocking the voltage applied to the LED columns. However, when only one LED element is broken when the LED driving circuit is used in the LED lighting device. There is a problem in that the lighting device is turned off so that it can no longer serve as the lighting device.

The present invention provides an LED lighting device to protect the LED device by correcting so that the applied current is constant by reducing the overall resistance variation between the LED array, when the current balance between the LED array is broken.

According to an aspect of the present invention, there is provided an LED lighting apparatus including: an LED module in which a plurality of LED arrays connected in series are connected in parallel; A constant current supply unit applying a constant current to the LED module; A variable resistor unit connected in series to each of the LED arrays; And a control unit controlling the constant current supply unit and the variable resistor unit, wherein the control unit calculates a compound resistance of each LED array when at least one of the measured current values of each LED array is out of a normal range, and calculates each LED array. If the synthesized resistors do not match, the variable resistor unit is adjusted to match the total resistance of each LED array to maintain current balance.

In the LED lighting apparatus according to an aspect of the present invention, the normal range may be 90% to 110% of the normal current.

In the LED lighting apparatus according to an aspect of the present invention, when the loss power generated by adjusting the variable resistors connected to each of the LED array is smaller than a predetermined reference value, the controller adjusts the variable resistors to match the overall resistance. Can be.

In the LED lighting apparatus according to an aspect of the present invention, the control unit is the normal range of the current value of each LED array, when the loss power generated by adjusting the variable resistors connected to each of the LED array is greater than a predetermined reference value The constant current supply unit may be controlled to accumulate current values of the LED arrays deviating from and to adjust the current value by the accumulated value of the increased or decreased current.

In the LED lighting apparatus according to an aspect of the present invention, the control unit is a range in which the loss power is equal to a predetermined reference value when the loss power generated by adjusting the variable resistors connected to each of the LED array is greater than a predetermined reference value. Adjust the variable resistance unit until the control unit, the current value of the LED array out of the normal range of the current value of each LED array in the state in which the variable resistance unit is adjusted and the constant current driver subtracts the adjusted current minus the accumulated current value from the rated current You can control the output.

In the LED lighting apparatus according to an aspect of the present invention, the reference value may be any value determined within 0.1% to 5% of the rated power.

According to an aspect of the present invention, an LED lighting apparatus further includes a temperature sensing unit configured to measure a temperature of a heat sink disposed in the LED module, wherein the controller is configured to control each of the LED arrays when the temperature of the heat sink is within a reference temperature range. The composite resistance can be calculated.

In the LED lighting apparatus according to an aspect of the present invention, when one or more of the measured current value of each LED array is out of the normal range, the control unit sequentially applies a measurement current to only one LED array to be applied to the corresponding LED array. By measuring the voltage (V _LED ), the composite resistance of each LED array is sequentially calculated, and the measured current may be a current value obtained by dividing the rated current by the number of the LED arrays.

In the LED lighting apparatus according to an aspect of the present invention, the controller may adjust the variable resistance connected in series with the remaining LED arrays based on the LED array having the largest synthetic resistance to match the total resistance of each LED array.

In the LED lighting apparatus according to an aspect of the present invention, the variable resistor unit may be any one selected from a transistor, a FET, a JFET, an EMOSFET, and a potentiometer.

An LED lighting apparatus according to an aspect of the present invention includes a current sensing unit connected in series to each of the LED arrays.

In the LED lighting apparatus according to an aspect of the present invention, the control unit blocks the corresponding LED array when at least one of the measured current value of each LED array is less than 30% or more than 130% of the normal current, The constant current supply unit may be controlled to reduce the current value by the number.

LED lighting device control method according to an aspect of the invention, the step of determining whether the current value of each LED array is in the normal range; Measuring a composite resistance of each of the LED arrays when a current value of at least one of the respective LED arrays is out of a normal range; Calculating correction resistances such that the total resistances of the respective LED arrays match when the combined resistances of the respective LED arrays do not match; And controlling the variable resistor unit to have the calculated correction resistor to match the total resistance of each of the LED arrays.

According to the present invention, when the current balance is not maintained due to the abnormality of the LED elements in one lighting device, the resistance of each LED array may be matched to maintain the current balance with a minimum power loss.

In addition, by maintaining the current balance, it is possible to suppress the failure of the LED array and the damage of other LED arrays above a specific LED element.

1 is a view for explaining the LED lighting apparatus according to an embodiment of the present invention,

2 is a flowchart illustrating a process of maintaining a current balance measured in each LED array according to an embodiment of the present invention.

3 is a flowchart illustrating a process of calculating a correction resistor to match the total resistance of each LED array.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In addition, it is to be understood that the accompanying drawings in the present invention are shown enlarged or reduced for convenience of description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the drawings. Like reference numerals designate like elements throughout, and duplicate descriptions thereof will be omitted.

1 is a view for explaining the LED lighting apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the LED lighting apparatus according to the present invention includes an LED module 20 in which a plurality of

LED arrays

21, 22... A constant current supply unit 10 for applying a constant current to the 20, a variable resistor unit 90 connected in series to each of the

LED arrays

21, 22 ... 2N, and the constant current supply unit 10 and the variable resistor unit ( 90 includes a control unit 50 for controlling.

The LED module 20 includes a plurality of

LED arrays

21, 22... 2N connected in parallel, and each

LED array

21, 22..., 2N has a plurality of LED elements connected in series. The size of the LED module 20 may be variously modified by the installation location, structure, and the like.

The constant current supply unit 10 is a well-known configuration for applying a constant current to each of the

LED arrays

21, 22 ... 2N. At this time, the DC input method includes a series pass method and a switching constant current method. The AC input method includes a converter method, and the output method outputs a DC constant current. It has the function to adjust the magnitude of the constant current output by the 5V control signal.

In addition, the constant current supply unit 10 may use a device controlled by a PWM method, and the constant current supply unit 10 may use a device controlled by a serial communication method such as RS485. The constant current supply unit 10 according to an embodiment of the present invention may be composed of a single constant current supply unit.

The variable resistor unit 90 is a type of current / voltage control element. The variable resistor unit 90 is connected in series to each of the

LED arrays

21, 22 ... 2N, and has a resistance in response to a gate voltage signal applied from the controller 50. It is configured to be variable. The variable resistor unit 90 may be any one selected from a transistor TR, a FET, a JFET, an EMOSFET, and a potentiometer.

The analog-to-digital converter 40 converts the current applied to each of the

LED arrays

21, 22..., 2N, the output voltage of the constant current supply unit 10, and the heat sink temperature information into a digital signal.

The sensing resistor 30 is connected in series to the

LED arrays

21, 22. At this time, it is preferable that the resistance value is designed to be extremely small so that the efficiency of the LED lighting device is not lowered. However, instead of the sensing resistor, the variable resistor unit 90 may be used to sense the current value of the

LED arrays

21, 22.

The control unit 50, when the power is applied, the set state of the constant current supply unit 10 (the normal state of the output voltage, the output constant current, the range of the maximum value, the minimum value) and the number of

LED arrays

21, 22 ... 2N. It reads the set value, current threshold, voltage threshold and temperature threshold related to the variable resistance control of each LED array according to LED protection conditions and LEDs per string.

In addition, the controller 50 uses the analog-to-digital converter 40 to output currents I1, I2, I3, I4, ˜In, the output voltage V _LED of the constant current supply unit 10, and temperature information of the heat sink. Receive

The controller 50 determines whether the measured current value of each of the

LED arrays

21, 22..., 2N is outside the normal range. At this time, the normal range of the LED array may be set to 90% to 110% of the normal current, but is not necessarily limited thereto.

One or more of the current values of the

LED arrays

21, 22 ... 2N deviate from the normal range because the specific LED element deteriorates and the operating voltage Vf increases or decreases.

If the current balance is broken in this way, the current increases or decreases in the

specific LED arrays

21, 22 ... 2N, and the brightness of the

LED arrays

21, 22 ... 2N as a whole is different so that uniform illumination cannot be maintained. . In addition, when the current applied to the specific LED array (21, 22 ... 2N) increases, there is a problem that the LED life is shortened.

Therefore, when it is determined that the current balance is broken, the controller 50 calculates the combined resistance (equivalent resistance) of the LEDs included in each

LED array

21, 22.

If the combined resistance of each of the

LED arrays

21, 22, ... 2N matches, there is an error other than the LED element.

However, when the combined resistance of each of the

LED arrays

21, 22 ... 2N does not match, it is determined that an abnormality has occurred in the LED element, and the variable resistor unit 90 is adjusted to adjust the

LED arrays

21, 22. The current balance is maintained by matching the total resistance of .2N) (composite resistance of the LED array + correction resistance of the variable resistor + sensing resistance).

Therefore, the current flowing through each

LED array

21, 22 ... 2N becomes constant again, so that the uniformity of light can be maintained at maximum, and the entire LED module becomes defective due to the abnormality of some LED elements of the LED module 20. Can be minimized.

In addition, since the variable resistor unit 90 is used without controlling the constant current supply unit 10, the current balance can be maintained with a minimum power loss.

In this case, it is preferable to calculate the composite resistance of each

LED array

21, 22... 2N when the temperature of the heat sink received from the temperature sensing unit 80 satisfies the reference temperature range.

However, even when the resistance value is adjusted using the variable resistor unit 90, power loss may occur. When the loss power is greater than a predetermined reference value, the controller 50 controls each

LED array

21, 22. 2N), the constant current supply unit 10 may be controlled to accumulate the current value of the LED array outside the normal range from the current value, and to adjust the current value by the accumulated value of the increased or decreased current.

However, in another method, the controller 50 adjusts the variable resistor unit 90 only to the extent that the total loss power is equal to a predetermined reference value, and then, among the current values of the LED arrays in the state where the variable resistor unit is adjusted, it is normal. The constant current supply unit 10 may be controlled to accumulate the current values of the LED arrays out of range and output the adjusted current minus the accumulated current value.

For example, when the reference value is 1% of the rated power, the variable resistor unit 90 is adjusted to a range corresponding to 1% of the rated power, and the normal resistance is corrected by the variable resistor unit 90. After accumulating the current value of the LED array out of range, it is possible to control the constant current supply unit 10 to output the adjusted current minus the accumulated current value.

At this time, the reference value is illustrated as 1% of the rated power, but may be arbitrarily determined in the range of 0.1% to 5% of the rated power.

The pulse width modulator 60 may control the magnitude of the constant current of the constant current supply unit 10 by adjusting and outputting the duty ratio of the pulse according to the signal received from the controller 50. However, as described above, the constant current supply unit 10 may select various interfaces other than the pulse width modulator.

The communication unit 70 is connected to the current state (I1 ~ In) of each LED array (21, 22 ... 2N), the total output current (IT) of the constant current supply unit 10, the output voltage (V _LED ) through the serial communication port , The heat sink temperature, etc. can be configured for remote monitoring, and the current control of the

LED arrays

21, 22 ... 2N (21, 22, 23, 24, ~ 2n) and the change of environmental setting value can be performed remotely. Provide a communication interface where possible. Through such a communication interface, correction resistance calculation control and variable resistance control, which will be described later, can be performed at a remote location, and the current balance between the LED arrays can be adjusted remotely.

2 is a flowchart illustrating a process of maintaining a current balance measured in each LED array according to an embodiment of the present invention, and FIG. 3 is a flowchart illustrating a process of calculating a correction resistor to match the total resistance to each LED array. .

The control method according to the present invention comprises the steps of determining whether the current value of each of the LED array (21, 22 ... 2N) is in the normal range (S10), and which of the LED array (21, 22 ... Measuring the combined resistance of each of the

LED arrays

21, 22 ... 2N when at least one current value is out of the normal range (S20), and If the synthesized resistance does not match, calculating the correction resistance so that the total resistance of each of the LED array (21, 22 ... 2N) (S30), and the variable resistor unit 90 to have the calculated correction resistance ) To match the total resistance of each of the

LED arrays

21, 22 ... 2N (S40).

First, step S10 of determining whether the current value of each of the

LED arrays

21, 22, ... 2N is in the normal range will be described. The controller 50 receives the information including the current values of each of the

LED arrays

21, 22 ... 2N (S11), and at least one of the

LED arrays

21, 22 ... 2N is outside the normal range. In this case, it is determined that an abnormality has occurred in the LED device (S12). In this case, the normal range may be set to 90% to 110% of the normal current.

At this time, the controller 50 determines whether the current value of the

LED arrays

21, 22, ... 2N is out of the threshold range (S13). The threshold range may be defined as a range of 30% or more and 130% or less of the normal current.

That is, when the current value of the

LED arrays

21, 22 ... 2N is less than 30% or more than 130% of the normal current, it is determined that the LED array is open or shorted, and the corresponding LED array is shut off and The constant current supply unit 10 is controlled (S14) so that the current value is reduced by the number of LED arrays.

However, if the current value of the

LED arrays

21, 22 ... 2N is outside the normal range but the threshold range is not exceeded, the LED element may be abnormal but not open or shorted. So that it no longer worsens.

Next, the step (S20) of measuring the combined resistance of each LED array (21, 22 ... 2N), and the step (S30) of calculating the correction resistance will be described in detail with reference to FIG.

First, in the step S20 of measuring the combined resistance of the

LED arrays

21, 22... 2N, the controller 50 may include structures, resistance variables, constant current information, and the like of the

LED arrays

21, 22. Read (S210).

Thereafter, the controller 50 reduces the constant current to maintain the measured current (S220). The measured current is the current value obtained by dividing the rated current by the number of N LED arrays (21, 22 ... 2N). For example, if there are five LED

arrays

21, 22, ... 2N, a measurement current corresponding to one fifth of the rated current is applied. That is, the normal current of the corresponding LED array is applied.

Thereafter, the variable resistor unit 90 is selectively switched (S230) to select the

LED arrays

21, 22..., 2N to be measured. For example, when the first LED array 21 is selected, only the variable resistor unit 90 of the first LED array 21 is switched on and the remaining N-1 LED arrays 22 ... 2N are switched on. Turn off to block.

Then, the controller 50 measures the output voltage (V _LED ) according to the operating voltage (Vf) of the plurality of LED elements included in the first LED array 21 (S240), and according to the following equation 1 the first LED The synthesized resistance (equivalent resistance) of the array 21 is calculated (S250).

[Relationship 1]

RAn = V _LED n / I (measurement current)

In the same manner, the combined resistance of the N-1 LED arrays 22 ... 2N is sequentially calculated.

Calculating the correction resistance (S30), if the measured synthetic resistance is different for each LED array (21, 22 ... 2N), the LED array with the largest synthetic resistance (that is, the array with the least current) As a reference, check each LED array and resistance deviation. Then, each correction resistance is calculated by the resistance deviation.

At this time, since the synthesis resistance, correction resistance, constant current information, etc. are stored in the memory, there is an advantage of knowing the resistance variation of the corresponding LED array.

Referring back to FIG. 2, in step S40 of matching the total resistance, the controller 50 determines whether the total loss power generated when the calculated correction resistor is applied is increased by 1% or more of the rated power (S41).

When the total loss power is less than 1% of the rated power, the variable resistor unit 90 is controlled to apply the correction resistor to match the total resistance of each of the

LED arrays

21, 22 ... 2N (S42).

As a result, when the total resistance of the LED array (composite resistance of the LED array + correction resistance of the variable resistor + sensing resistance) is matched, the current is again balanced.

However, when the total loss power generated by adjusting the variable resistor unit 90 connected to each

LED array

21, 22 ... 2N is 1% or more of the rated power, each

LED array

21, 22 ... 2N is used. After accumulating the current value out of the normal range among the current values of 2N), the constant current supply unit 10 may be controlled (S43) so that the current value is adjusted by the accumulated value of the increased or decreased current.

Alternatively, the variable resistance unit 90 is adjusted to a range where the loss power is equal to a predetermined reference value, and the current values of the LED arrays outside the normal range are accumulated in the state where the overall resistance is corrected by the variable resistance unit 90. Thereafter, the constant current supply unit 10 may be controlled to output the adjustment current minus the accumulated current value from the rated current.

As mentioned above, although the invention made by this inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

Claims

An LED module in which a plurality of LED arrays connected in series with a plurality of LED elements are connected in parallel;

A constant current supply unit applying a constant current to the LED module;

A variable resistor unit connected in series to each of the LED arrays; And

It includes a control unit for controlling the constant current supply and the variable resistor,

The control unit, if one or more of the measured current value of each of the LED array is out of the normal range by adjusting the variable resistor to match the total resistance of each LED array to maintain a current balance.
The method of claim 1,

The control unit calculates a compound resistance of each LED array when at least one of the measured current value of each LED array is out of the normal range, and adjusts the variable resistance unit when the compound resistance of each LED array does not match. , Wherein the normal range is 90% to 110% of the normal current.
The method of claim 2,

If the loss power generated by adjusting the variable resistors connected to each of the LED array is less than a predetermined reference value,

LED lighting device to match the overall resistance by adjusting the variable resistor.
The method of claim 2,

The controller may control the variable resistors connected to each of the LED arrays when the loss power generated by the controller is greater than a predetermined reference value.

Adjusting the variable resistance portion to the range that the loss power is equal to a predetermined reference value,

LED lighting device for controlling the current value of the LED array out of the normal range from the current value of each LED array in the state in which the variable resistor unit is adjusted and the constant current driver outputs the adjusted current minus the accumulated current value. .
The method according to claim 3 or 4,

The reference value is an LED lighting device of any value determined within 0.1% to 5% of the rated power.
The method of claim 2,

The control unit, if one or more of the measured current value of each LED array is out of the normal range,

LED lighting device that sequentially calculates the composite resistance of each LED array by measuring the voltage (V LED ) applied to the LED array by applying a measurement current to only one LED array in sequence.
The method of claim 6,

The control unit adjusts the variable resistance connected in series with the remaining LED array on the basis of the LED array having the largest synthetic resistance LED lighting device to match the total resistance of each LED array.
The method of claim 1,

The LED lighting device to control the setting value of the lighting device through an interface connected to the control unit at a remote location, LED lighting device for monitoring the state of the lighting device.
The method of claim 1,

LED lighting device comprising a current sensing unit connected to each of the LED array in series.
The method of claim 2,

If the at least one measured current value of each LED array is less than 30% or more than 130% of the normal current, the controller is configured to shut off the corresponding LED array and reduce the current value by the number of blocked LED arrays. LED lighting device to control.
Determining whether a current value of each LED array is within a normal range;

Measuring a composite resistance of each of the LED arrays when a current value of at least one of the respective LED arrays is out of a normal range;

Calculating correction resistances such that the total resistances of the respective LED arrays match when the combined resistances of the respective LED arrays do not match;

And controlling the variable resistor unit to have the calculated correction resistance to match the total resistance of each of the LED arrays.
The method of claim 11, wherein the calculating of the correction resistance comprises:

LED lighting device control method for sequentially calculating the combined resistance of each LED array by sequentially applying a measurement current to only one LED array and measuring the voltage (V LED ) applied to the corresponding LED array.
The method of claim 11, wherein in the step of matching the total resistance,

When the loss power generated by adjusting the variable resistors connected to each LED array is smaller than a predetermined reference value,

LED lighting device control method of adjusting the variable resistor to match the overall resistance.