CN104765907A - LED apparatus junction temperature and thermal power prediction method - Google Patents

Abstract

The invention discloses an LED apparatus junction temperature and thermal power prediction method. The method comprises S1, calculating a first characteristic parameter cti and a second characteristic parameter ct0 for describing LED apparatus temperature coefficients ct; S2, calculating a third characteristic parameter ci and a fourth characteristic parameter co of the LED apparatus; S3, predicting the junction temperature Tj of the LED apparatus under any currents according to energy conversion efficiency eta w under different input currents; S4, predicting the thermal power Pheat of the LED apparatus under any currents according to the LED apparatus function temperature Tj under different input currents. The method is simple to operate, predictors can obtain parameters in a mathematical model by only measuring energy conversion efficiency of the LED apparatus in the four operation conditions, and the junction temperature and the thermal power of the LED apparatus under any operation currents can be predicted by substituting the parameters into software tools formed by the mathematical models.

Description

The junction temperature temperature of LED component and the Forecasting Methodology of thermal power

Technical field

The present invention relates to LED information display system optical property and thermal behavior electric powder prediction, particularly relate to a kind of junction temperature temperature of LED component and the Forecasting Methodology of thermal power.

Background technology

Along with the development of semiconductor technology, the performance of great power LED system obtains and improves significantly.Great power LED system will be expected to and becomes the lighting source that can replace incandescent lamp and fluorescent light gradually.Up to the present, the efficiency of LED considerably beyond incandescent lamp, and is being caught up with gradually and is being made great efforts to exceed fluorescent light, and it has become a kind of novel green illumination light source.Compared with fluorescent light, LED has many good qualities, and such as easily light modulation, does not need inert gas strong, non-friable etc. to produce plasma, stability.But although LED has so many advantages, its application at present is still confined to middle low power applications, as low power applications in decoration, display, electric torch, automobile headlamp etc., in public illumination field, LED can't replace fluorescent light completely.

Nowadays, high power LED device enters into public illumination field just gradually.Compared with conventional gas discharge lamp, LED has many good qualities, such as high-level efficiency, high anti-seismic performance, long-life etc., low-energy-consumption etc.In the near future, LED component becomes most popular lighting source by being expected to.Different from gas-discharge lamp, LED component launches infrared and ultraviolet light hardly.Be injected into the electric power of LED component except producing useful visible ray, remainder will all for generation of heat energy.But as a kind of solid-state semiconductor device, this part heat energy can only dissipate with convection current by passing to, and not by the mode of radiation.Because heat radiation and thermal effect analysis will be important research directions in field of LED illumination.Wherein predict that LED junction temperature temperature and heat radiation power are important steps.

At present, researchers have proposed the method for several prediction junction temperature temperature.Wherein, certain methods depends on searching temperature-sensitivity coefficient.As peak wavelength method, the method for total radiation energy and the ratio of the emittance of blue light, forward voltage method etc.In addition, certain methods then depends on special Setup Experiments, and these technology comprise: heat picture method, Raman optical spectrum method, and nematic liquid crystal method.

For the defect of the method for the junction temperature of at present existing prediction LED component and deficiency be: the first prescription method, namely the method finding temperature-sensitivity coefficient is depended on, this kind of method is when searching temperature-sensitivity coefficient, need a large amount of prior calibration operations, so just make prediction work become loaded down with trivial details.Second prescription method, namely depends on the method for special Setup Experiments, and they all need the measuring method of expensive and meticulous experimental facilities and specialty, and this makes the second prescription method can not be widely used in industry.

In addition, the research method for thermal power prediction is also few, and comparatively common is exactly predict thermal power by the searching heat rejection coefficient of LED component and the thermal resistance of LED component.

Therefore, for above-mentioned technical matters, need to propose a kind of junction temperature temperature of LED component and the Forecasting Methodology of thermal power.

Summary of the invention

In view of this, in order to solve existing deficiency, the invention provides a kind of junction temperature temperature of LED component and the Forecasting Methodology of thermal power.

To achieve these goals, the technical scheme that provides of the embodiment of the present invention is as follows:

A Forecasting Methodology for the junction temperature temperature of LED component, said method comprising the steps of:

S1, to calculate for describing LED component temperature coefficient c _tthe first characterisitic parameter c _tiwith the second characterisitic parameter c _to, described temperature coefficient c _tfor energy conversion efficiency η during driving current constant _wwith junction temperature temperature T _jthe slope declined also is energy conversion efficiency η _wwith LED component skin temperature T _cthe slope declined;

3rd characterisitic parameter c of S2, calculating LED component _iwith the 4th characterisitic parameter c _o;

S3, according to formula input the energy conversion efficiency η under different electric current _w, predict the junction temperature temperature T of the LED component under any electric current _j, wherein, T _ofor constant junction temperature.

As a further improvement on the present invention, described step S1 is specially:

S11, measurement LED component electric current I ₁under temperature coefficient c _t1, temperature coefficient c _t1for electric current I ₁lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S12, measurement LED component electric current I ₂under temperature coefficient c _t2, temperature coefficient c _t2for electric current I ₂lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S13, by electric current I ₁with temperature coefficient c _t1, electric current I ₂with temperature coefficient c _t2substitute into formula c respectively _t=c _tilnI+c _toin, calculate the first characterisitic parameter c _tiwith the second characterisitic parameter c _to.

As a further improvement on the present invention, in described step S1,

Step S11 is specially:

Use constant current source I ₁driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₁energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₁invariable, be T in skin temperature _c2be I with drive current ₁the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₁under temperature coefficient c _t1;

Step S12 is specially:

Use constant current source I ₂driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₂energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₂invariable, be T in skin temperature _c2be I with drive current ₂the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₂under temperature coefficient c _t2.

As a further improvement on the present invention, described step S2 is specially:

S21, in electric current I ₁the energy conversion efficiency of lower measurement LED component be designated as

S22, in electric current I ₂the energy conversion efficiency of lower measurement LED component be designated as

S23, by electric current I ₁and energy conversion efficiency electric current I ₂and energy conversion efficiency substitute into respectively in, calculate the 3rd characterisitic parameter c of LED component _iwith the 4th characterisitic parameter c _o, wherein, be the junction temperature temperature of LED component be T _ounder the energy conversion efficiency of LED component.

As a further improvement on the present invention, described step S2 also comprises:

According to T _c=T _j-R _jck _hp _dthe skin temperature of LED component is set, wherein, T _cfor the skin temperature of LED component, T _jfor the junction temperature temperature of LED component, T in step s 2 _j=T _o, R _jcfor the thermal resistance of LED component, k _hfor the heat rejection coefficient of LED component, P _dfor the electric power of LED component.

Correspondingly, a kind of Forecasting Methodology of thermal power of LED component, said method comprising the steps of:

S1, to calculate for describing LED component temperature coefficient c _tthe first characterisitic parameter c _tiwith the second characterisitic parameter c _to, described temperature coefficient c _tfor energy conversion efficiency η during driving current constant _wwith junction temperature temperature T _jthe slope declined also is energy conversion efficiency η _wwith LED component skin temperature T _cthe slope declined;

3rd characterisitic parameter c of S2, calculating LED component _iwith the 4th characterisitic parameter c _o;

S3, according to formula input the energy conversion efficiency η under different electric current _w, predict the junction temperature temperature T of the LED component under any electric current _j, wherein, T _ofor constant junction temperature;

S4, according to formula P _heat=[1+ (c _tilnI+c _to) (T _j-T _o)-c _oexp (-c _ii)] P _d, input the junction temperature temperature T of the LED component under different electric current _j, predict the thermal power P of the LED component under any electric current _heat, wherein, P _dfor the electric power of LED component.

As a further improvement on the present invention, described step S1 is specially:

S11, measurement LED component electric current I ₁under temperature coefficient c _t1, temperature coefficient c _t1for electric current I ₁lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S12, measurement LED component electric current I ₂under temperature coefficient c _t2, temperature coefficient c _t2for electric current I ₂lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S13, by electric current I ₁with temperature coefficient c _t1, electric current I ₂with temperature coefficient c _t2substitute into formula c respectively _t=c _tilnI+c _toin, calculate the first characterisitic parameter c _tiwith the second characterisitic parameter c _to.

As a further improvement on the present invention, in described step S1,

Step S11 is specially:

Use constant current source I ₁driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₁energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₁invariable, be T in skin temperature _c2be I with drive current ₁the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₁under temperature coefficient c _t1;

Step S12 is specially:

Use constant current source I ₂driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₂energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₂invariable, be T in skin temperature _c2be I with drive current ₂the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₂under temperature coefficient c _t2.

As a further improvement on the present invention, described step S2 is specially:

S21, in electric current I ₁the energy conversion efficiency of lower measurement LED component be designated as

S22, in electric current I ₂the energy conversion efficiency of lower measurement LED component be designated as

S23, by electric current I ₁and energy conversion efficiency electric current I ₂and energy conversion efficiency substitute into respectively in, calculate the 3rd characterisitic parameter c of LED component _iwith the 4th characterisitic parameter c _o, wherein, be the junction temperature temperature of LED component be T _ounder the energy conversion efficiency of LED component.

As a further improvement on the present invention, described step S2 also comprises:

According to T _c=T _j-R _jck _hp _dthe skin temperature of LED component is set, wherein, T _cfor the skin temperature of LED component, T _jfor the junction temperature temperature of LED component, T in step s 2 _j=T _o, R _jcfor the thermal resistance of LED component, k _hfor the heat rejection coefficient of LED component, P _dfor the electric power of LED component.

Junction temperature temperature proposed by the invention and the Forecasting Methodology of thermal power all have characteristic simple to operate, dopester only need measure the energy conversion efficiency under four conditions of work of LED component, just the parameter in mathematical model can be obtained, parameter is updated in the Software tool weaved into by mathematical model, just can dopes the junction temperature temperature of LED component under any working current and thermal power.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, the accompanying drawing that the following describes is only some embodiments recorded in the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the junction temperature temperature T of LED component of the present invention _jforecasting Methodology process flow diagram;

Fig. 2 is the thermal power P of LED component of the present invention _heatforecasting Methodology process flow diagram;

Fig. 3 is at drive current I in the present invention one specific embodiment ₁under=0.3A, energy conversion efficiency curve map during two kinds of different LED device outer case temperature of measurement;

Fig. 4 is at drive current I in the present invention one specific embodiment ₂under=0.7A, energy conversion efficiency curve map during two kinds of different LED device outer case temperature of measurement;

Fig. 5 is the junction temperature temperature comparison diagram under different electric current of prediction and measurement in the present invention one specific embodiment;

Fig. 6 is the thermal power comparison diagram under different driving electric current of prediction and measurement in the present invention one specific embodiment.

Embodiment

Technical scheme in the present invention is understood better in order to make those skilled in the art person, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, should belong to the scope of protection of the invention.

The invention discloses a kind of junction temperature temperature T of LED component _jwith thermal power P _heatforecasting Methodology, method proposed by the invention is junction temperature temperature for predicting LED component and thermal power, and preferably, LED component is high light large power LED device.

Shown in ginseng Fig. 1, a kind of junction temperature temperature T of LED component _jforecasting Methodology, comprise the following steps:

S1, to calculate for describing LED component temperature coefficient c _tthe first characterisitic parameter c _tiwith the second characterisitic parameter c _to, described temperature coefficient c _tfor energy conversion efficiency η during driving current constant _wwith junction temperature temperature T _jthe slope declined also is energy conversion efficiency η _wwith LED component skin temperature T _cthe slope declined, above-mentioned two slopes are equal;

3rd characterisitic parameter c of S2, calculating LED component _iwith the 4th characterisitic parameter c _o;

S3, according to formula input the energy conversion efficiency η under different electric current _w, predict the junction temperature temperature T of the LED component under any electric current _j, wherein, T _ofor constant junction temperature.

The junction temperature temperature T of LED component in the embodiment of the invention _jforecasting Methodology be specially:

Find the characterisitic parameter c of LED component _tiand c _to.The characterisitic parameter c of LED component _tiand c _tofor describing LED component energy conversion efficiency η _wtemperature coefficient c _t, temperature coefficient c herein _trefer to the slope that energy conversion efficiency declines with junction temperature temperature.Therefore, characterisitic parameter c _tiand c _toby finding temperature coefficient c _t, the slope that namely energy conversion efficiency of LED component declines with junction temperature temperature obtains.

First, constant current source I is used ₁driving LED device, is now arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₁energy conversion efficiency under condition, and be designated as η _w1.Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₁invariable, be T in skin temperature _c2be I with drive current ₁measure the energy conversion efficiency of this LED component under condition, and be designated as η _w2.This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on, change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₁under temperature coefficient, be designated as c _t1, namely in electric current I ₁under energy conversion efficiency be c with the slope that temperature declines _t1.

Step 2, carry out second time test to LED component, the drive current changing LED component is I ₂, repeat the work of step one.Respectively the shell of LED component is set to two different temperature, and respectively under these two different temperatures, measures the energy conversion efficiency of LED component.Thus obtain in electric current I ₂under the slope that declines with temperature of energy conversion efficiency, be designated as c _t2, namely in electric current I ₂the temperature coefficient of lower LED component is c _t2.

Step 3, utilizes the mathematical model (1) of temperature coefficient proposed by the invention.The temperature coefficient of the energy conversion efficiency that mathematical model (1) proposes first for the present invention is with the expression formula of curent change.

c _t＝c _tilnI+c _to(1)

Step one and step 2 are measured obtain in electric current I ₁under temperature coefficient c _t1, and in electric current I ₂under temperature coefficient c _t2, be updated to respectively in mathematical model (1), just obtain two with c _tiand c _toformula for unknown quantity:

c _t1＝c _tilnI ₁+c _to(2)

c _t2＝c _tilnI ₂+c _to(3)

In formula (2) and (3), I ₁and I ₂being the drive current in step one and step 2, is known quantity, c _t1and c _t1being the temperature coefficient obtained in step one and step 2, is also known quantity.

Solution formula (2) and (3), just can obtain the characterisitic parameter c of LED component _tiand c _to.

Step 4, determines two other characterisitic parameter c of LED component _iand c _o.Characterisitic parameter c _iand c _odetermination can pass through, measure respectively value under two different driving electric currents obtains.Wherein, referring to junction temperature temperature is T _ounder the energy conversion efficiency of LED component.

T is operated in order to make the junction temperature of LED component _o.The skin temperature of LED component needs by relation T _c=T _j-R _jck _hp _darrange, wherein, T _cfor the skin temperature of LED component, T _jfor the junction temperature temperature of LED component, T herein _j=T _o, R _jcfor the thermal resistance of LED component, k _hfor the heat rejection coefficient of LED component, P _dfor the electric power of LED component.

In electric current I ₁lower measurement and be designated as measure for 2 times in electric current I and be designated as

Step 5, making full use of junction temperature temperature proposed by the invention is T _ounder the mathematical model of energy conversion efficiency.Mathematical model (4) for the junction temperature that the present invention proposes first be T _ounder the mathematical model of energy conversion efficiency.

$\mathrm{\η}{|}_{T_o}=c_o\exp (-c_{i}I)---\left(4\right)$

Will with be updated to respectively in mathematical model (4), just can obtain with c _iand c _otwo equations for unknown quantity:

$\mathrm{\η}{|}_{T_o-1}=c_o\exp (-c_i{I}_1)---\left(5\right)$

$\mathrm{\η}{|}_{T_o-2}=c_o\exp (-c_i{I}_2)---\left(6\right)$

I in formula (5) and (6) ₁and I ₂being the drive current in step 4, is known quantity, with being obtain in step 4, is also known quantity.Solution formula (5) and (6), just can obtain the characterisitic parameter c of LED component _iand c _o.

Step 6, makes full use of the relational expression (7) of next energy conversion efficiency proposed by the invention and junction temperature temperature.The relational expression of the energy conversion efficiency that mathematical model (7) puts forward first for the present invention and junction temperature temperature, it is applicable to the LED component of any model.Four parameters in mathematical model (7), c _ti, c _to, c _iand c _o, obtain by the method for step one to step 5.

$T_j=\frac{{\mathrm{\η}}_w-c_o\exp (-c_{i}I)}{-(c_{\mathrm{ti}}\ln I+c_{\mathrm{to}})}+T_o---\left(7\right)$

The coefficient c that step 3 is obtained _tiand c _to, and the coefficient c that step 5 obtains _iand c _o, be updated in mathematical model (7), just obtain the mathematical model of the concrete junction temperature temperature of this LED component.Now, the energy conversion efficiency η under different electric current only need be inputted in mathematical model _w, just can predict the junction temperature temperature of the LED component under any working current.

Step 7, the model of the junction temperature temperature of the concrete LED component obtained in step 6 is written as computer program, and the Software tool formed on computer, so just the mathematical model of the junction temperature temperature of this concrete device is carried out Software tool, as long as input service electric current in Software tool, with the energy conversion efficiency measured under this working current, the junction temperature temperature of the LED component under this condition of work just can be doped.

Shown in ginseng Fig. 2, a kind of thermal power P of LED component _heatforecasting Methodology, comprise the following steps:

S1, to calculate for describing LED component temperature coefficient c _tthe first characterisitic parameter c _tiwith the second characterisitic parameter c _to, described temperature coefficient c _tfor energy conversion efficiency η during driving current constant _wwith junction temperature temperature T _jthe slope declined also is energy conversion efficiency η _wwith LED component skin temperature T _cthe slope declined;

3rd characterisitic parameter c of S2, calculating LED component _iwith the 4th characterisitic parameter c _o;

S3, according to formula input the energy conversion efficiency η under different electric current _w, predict the junction temperature temperature T of the LED component under any electric current _j, wherein, T _ofor constant junction temperature;

S4, according to formula P _heat=[1+ (c _tilnI+c _to) (T _j-T _o)-c _oexp (-c _ii)] P _d, input the junction temperature temperature T of the LED component under different electric current _j, predict the thermal power P of the LED component under any electric current _heat, wherein, P _dfor the electric power of LED component.

The thermal power P of LED component in the embodiment of the invention _heatforecasting Methodology be specially:

Step one is identical with the Forecasting Methodology of junction temperature temperature Tj to seven, does not repeat them here.

Step 8, utilizes the mathematical model of the thermal power of LED component proposed by the invention to predict the thermal power of LED component.The mathematical model of the thermal power of the LED component that mathematical model (8) proposes first for the present invention:

P _heat＝[1+(c _tilnI+c _to)(T _j-T _o)-c _oexp(-c _iI)]P _d(8)

By the coefficient c obtained in step one to step 5 _ti, c _to, c _iand c _o, be updated in the mathematical model (8) of the thermal power of LED component proposed by the invention, just obtain the mathematical model of the concrete thermal power of this LED component.

Step 9, is written as computer program by the mathematical model of the thermal power of the concrete LED component obtained in step 8, just defines the Software tool of the thermal power of the prediction LED component on computer.Deviser only need input working current and the junction temperature temperature of LED component in software, just can obtain the value of the thermal power of the LED component predicted.

The technological means realized for making the present invention, creation characteristic, reaching object and effect is easy to understand, below in conjunction with embodiment, setting forth the present invention further.

The present embodiment method proposed by the invention predicts junction temperature temperature and the thermal power of a LEDs device, and the model of SEOUL N42180 LED component used is: N42180-EC01.

In the present embodiment with constant junction temperature T _o=25 DEG C are described, and also can be set to other temperature values in other embodiments.

Step one, finds the characterisitic parameter c of this LED component _tiand c _to.

First, constant current source I is used ₁=0.3A driving LED device, is now arranged to T by the skin temperature of LED component _c1=40 DEG C, measuring in skin temperature is T _c1=40 DEG C is I with drive current ₁energy conversion efficiency under=0.3A condition is η _w1=18.76.Secondly, the skin temperature changing LED component is T _c2=69.6 DEG C, drive current maintains I ₁=0.3A is invariable, is T in skin temperature _c2=69.6 DEG C is I with drive current ₁the energy conversion efficiency measuring this LED component under=0.3A condition is η _w2=18.00.Two points (40 DEG C, 18.76) obtain this measurement and (69.6 DEG C, 18.00) are placed on, and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, as shown in Figure 3.The slope of this straight line is 0.0259, namely in electric current I ₁the temperature coefficient of the energy conversion efficiency under=0.3A is c _t1=0.0259.

Step 2, carry out second time test to LED component, the drive current changing LED component is I ₂=0.7A, repeats the work of step one.Respectively the shell of LED component is set to two different temperature, T _c1=40 DEG C and T _c2=69.6 DEG C.At both temperatures, the energy conversion efficiency of the LED component of measurement as shown in Figure 4.According to the slope of the straight line of point-to-point transmission in Fig. 4, can obtain the slope that energy conversion efficiency declines with temperature is 0.0291, is designated as c _t2=0.0291, namely in electric current I ₂under=0.7A, the temperature coefficient of LED component is c _t2=0.0291.

Step 3, utilizes the mathematical model (1) of temperature coefficient proposed by the invention.The temperature coefficient of the energy conversion efficiency that mathematical model (1) proposes first for the present invention is with the expression formula of curent change.

c _t＝c _tilnI+c _to(1)

Step one and step 2 are measured obtain in electric current I ₁temperature coefficient c under=0.3A _t1=0.0259, and in electric current I ₂temperature coefficient c under=0.7A _t2=0.0291, be updated to respectively in mathematical model (1), just obtain two with c _tiand c _toformula for unknown quantity:

0.0259＝c _tiln(0.3)+c _to(2)

0.0291＝c _tiln(0.7)+c _to(3)

Solution formula (2) and (3), just can obtain the characterisitic parameter c of LED component _ti=0.0037 and c _to=0.0304.

Step 4, determines two other characterisitic parameter c of LED component _iand c _o.Characterisitic parameter c _iand c _odetermination can pass through, measure η respectively | _{25 DEG C}value under two different driving electric currents obtains.Wherein, η | _{25 DEG C}refer to the energy conversion efficiency that junction temperature temperature is the LED component at 25 DEG C.

At drive current I ₁under=0.3A, in order to make the junction temperature of LED component be operated in 25 DEG C, namely in order to make T _j=25 DEG C, the skin temperature of LED component need by relation T _c=T _j-R _jck _hp _d=25-0.743*13 is set to T _c=15.3 DEG C, the η now measured | _{25 DEG C-1}=19.23.In electric current I ₂during=0.6A, be 25 DEG C in order to ensure LED junction temperature, the skin temperature of LED component is set to T _c=3.7 DEG C (by relational expression T _c=T _j-R _jck _hp _d=25-1.64*13 arranges Tc), the η of measurement | _{25 DEG C-2}=16.146.

Step 5, utilizes junction temperature proposed by the invention to be the mathematical model of the energy conversion efficiency at 25 DEG C.Mathematical model (4) for junction temperature that the present invention proposes first be 25 DEG C at the mathematical model of energy conversion efficiency.

η| _25℃＝c _oexp(-c _iI) (4)

By (I ₁=0.3A, η | _{25 DEG C-1}=19.23) and (I ₂=0.6A, η | _{25 DEG C-2}=16.146) be updated to respectively in mathematical model (4), just can obtain with c _iand c _otwo equations for unknown quantity:

19.23＝c _oexp(-0.3c _i) (5)

16.146＝c _oexp(-0.6c _i) (6)

Solution formula (5) and (6), just can obtain the characterisitic parameter c of LED component _i=0.58 and c _o=22.9.

Step 6, utilizes the relational expression (7) of next energy conversion efficiency proposed by the invention and junction temperature temperature.The relational expression of the energy conversion efficiency that mathematical model (7) puts forward first for the present invention and junction temperature temperature, it is applicable to the LED component of any model, wherein T _o=25 DEG C.Four parameters in mathematical model (7), c _ti, c _to, c _iand c _o, obtain by the method for step one to step 5.

$T_j=\frac{{\mathrm{\η}}_w-c_o\exp (-c_{i}I)}{-(c_{\mathrm{ti}}\ln I+c_{\mathrm{to}})}+T_o---\left(7\right)$

The coefficient c that step 3 is obtained _ti=0.0037 and c _to=0.0304, and the coefficient c that step 5 obtains _i=0.58 and c _o=22.9, be updated in mathematical model (7), just obtain the mathematical model of the concrete junction temperature temperature of this LED component, shown in (8)

$T_j=\frac{{\mathrm{\η}}_w-22.9\exp (-0.58I)}{-(0.0037\ln I+0.0304)}+T_o---\left(8\right)$

Now, the energy conversion efficiency η under different electric current only need be inputted in mathematical model (8) _w, just can predict the junction temperature temperature of the LED component under any working current.

Step 7, is written as computer program by the model of the junction temperature temperature of the concrete LED component obtained in step 6, and forms the Software tool on computer.So just the mathematical model of the junction temperature temperature of this concrete device is carried out Software tool, as long as input service electric current in Software tool, with the energy conversion efficiency measured under this working current, the junction temperature temperature of the LED component under this condition of work just can be doped.

Step 8, measures the energy conversion efficiency under different electric current, and table 1 is the energy conversion efficiency under different electric current measured.Energy conversion efficiency in table 1 and electric current are updated in the software weaved into according to mathematical model (8) in step 6, just can predict the junction temperature of this LEDs device.The junction temperature temperature of this SEOUL LED component of circular some representative prediction in Fig. 5, triangle form point is the junction temperature temperature using specific apparatus to measure.Can be seen by Fig. 5, the point of the point that circle is predicted and triangulation is very close, demonstrates the correctness of the method.

Table 1: the energy conversion efficiency of SEOUL LED component under different electric current of measurement

Electric current (A)	0.3	0.4	0.5	0.6	0.7
						Energy conversion efficiency (%)	19.00	17.70	16.57	15.50	14.56

Step 9, utilizes the mathematical model of the thermal power of LED component proposed by the invention to predict the thermal power of LED component.The mathematical model of the thermal power of the LED component that mathematical model (9) proposes first for the present invention:

P _heat＝[1+(c _tilnI+c _to)(T _j-T _o)-c _oexp(-c _iI)]P _d(9)

By the coefficient c obtained in step one to step 5 _ti=0.0037, c _to=0.0304, c _i=0.58 and c _o=22.9, be updated in the mathematical model (9) of the thermal power of LED component proposed by the invention, just obtain the mathematical model of the concrete thermal power of this LED component.Such as formula (10).

P _heat＝[1+(0.0037lnI+0.0304)(T _j-T _o)

-22.9exp(-0.58I)]P _d(10)

Wherein, T _o=25 DEG C.

Step 10, is written as computer program by the mathematical model of the thermal power of the concrete LED component obtained in step 9, just defines the Software tool of the thermal power of the prediction LED component on computer.Deviser only need input working current and the junction temperature temperature of LED component in software, just can obtain the value of the thermal power of the LED component predicted.

Step 11, is brought into the junction temperature temperature of this LED component calculated in Fig. 5 of step 8 and corresponding electric current in the software weaved into according to mathematical model (10) in step 9, just can predicts the thermal power of this LEDs device.Fig. 6 is the thermal power of this LED component of prediction and measurement.Value and the value of measurement of prediction are very close, demonstrate the correctness of the method.

In sum, the present invention has following beneficial effect:

The Forecasting Methodology of the junction temperature temperature of LED component of the present invention, the method that relatively, researcher proposes, more simple and feasible.By the mathematical model of junction temperature temperature proposed by the invention, gauger only need input electric current and the energy conversion efficiency of LED component in prototype software, just directly can dope the junction temperature temperature of LED component.

Because energy conversion efficiency adopts common photometric measurement instrument, the junction temperature temperature methods proposed also does not rely on expensive experimental equipment, complicated Setup Experiments is not relied on yet, therefore, the method proposed has more general applicability and convenience, potential be suitable for by vast LED manufacturer.

In addition, the Forecasting Methodology of thermal power proposed by the invention, possesses simple accurate characteristic equally, does not relate to this parameter of thermal resistance between LED component shell band knot face, improve simplicity and the accuracy of measurement in the thermal power mathematical model simultaneously proposed.

Generally speaking, junction temperature temperature proposed by the invention and the Forecasting Methodology of thermal power all have characteristic simple to operate, dopester only need measure the energy conversion efficiency under four conditions of work of LED component, just the parameter in mathematical model can be obtained, parameter is updated in the Software tool weaved into by mathematical model, just can dopes the junction temperature temperature of LED component under any working current and thermal power.

To those skilled in the art, obviously the invention is not restricted to the details of above-mentioned one exemplary embodiment, and when not deviating from spirit of the present invention or essential characteristic, the present invention can be realized in other specific forms.Therefore, no matter from which point, all should embodiment be regarded as exemplary, and be nonrestrictive, scope of the present invention is limited by claims instead of above-mentioned explanation, and all changes be therefore intended in the implication of the equivalency by dropping on claim and scope are included in the present invention.Any Reference numeral in claim should be considered as the claim involved by limiting.

In addition, be to be understood that, although this instructions is described according to embodiment, but not each embodiment only comprises an independently technical scheme, this narrating mode of instructions is only for clarity sake, those skilled in the art should by instructions integrally, and the technical scheme in each embodiment also through appropriately combined, can form other embodiments that it will be appreciated by those skilled in the art that.

Claims (10)

1. a Forecasting Methodology for the junction temperature temperature of LED component, is characterized in that, said method comprising the steps of:

S1, to calculate for describing LED component temperature coefficient c _tthe first characterisitic parameter c _tiwith the second characterisitic parameter c _to, described temperature coefficient c _tfor energy conversion efficiency η during driving current constant _wwith junction temperature temperature T _jthe slope declined also is energy conversion efficiency η _wwith LED component skin temperature T _cthe slope declined;

3rd characterisitic parameter c of S2, calculating LED component _iwith the 4th characterisitic parameter c _o;

S3, according to formula input the energy conversion efficiency η under different electric current _w, predict the junction temperature temperature T of the LED component under any electric current _j, wherein, T _ofor constant junction temperature.

2. method according to claim 1, is characterized in that, described step S1 is specially:

S11, measurement LED component electric current I ₁under temperature coefficient c _t1, temperature coefficient c _t1for electric current I ₁lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S12, measurement LED component electric current I ₂under temperature coefficient c _t2, temperature coefficient c _t2for electric current I ₂lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S13, by electric current I ₁with temperature coefficient c _t1, electric current I ₂with temperature coefficient c _t2substitute into formula c respectively _t=c _tilnI+c _toin, calculate the first characterisitic parameter c _tiwith the second characterisitic parameter c _to.

3. method according to claim 2, is characterized in that, in described step S1,

Step S11 is specially:

Use constant current source I ₁driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₁energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₁invariable, be T in skin temperature _c2be I with drive current ₁the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₁under temperature coefficient c _t1;

Step S12 is specially:

Use constant current source I ₂driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₂energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₂invariable, be T in skin temperature _c2be I with drive current ₂the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₂under temperature coefficient c _t2.

4. method according to claim 1, is characterized in that, described step S2 is specially:

S21, in electric current I ₁the energy conversion efficiency of lower measurement LED component be designated as

S22, in electric current I ₂the energy conversion efficiency of lower measurement LED component be designated as

S23, by electric current I ₁and energy conversion efficiency electric current I ₂and energy conversion efficiency substitute into respectively in, calculate the 3rd characterisitic parameter c of LED component _iwith the 4th characterisitic parameter c _o, wherein, be the junction temperature temperature of LED component be T _ounder the energy conversion efficiency of LED component.

5. method according to claim 1, is characterized in that, described step S2 also comprises:

According to T _c=T _j-R _jck _hp _dthe skin temperature of LED component is set, wherein, T _cfor the skin temperature of LED component, T _jfor the junction temperature temperature of LED component, T in step s 2 _j=T _o, R _jcfor the thermal resistance of LED component, k _hfor the heat rejection coefficient of LED component, P _dfor the electric power of LED component.

6. a Forecasting Methodology for the thermal power of LED component, is characterized in that, said method comprising the steps of:

S1, to calculate for describing LED component temperature coefficient c _tthe first characterisitic parameter c _tiwith the second characterisitic parameter c _to, described temperature coefficient c _tfor energy conversion efficiency η during driving current constant _wwith junction temperature temperature T _jthe slope declined also is energy conversion efficiency η _wwith LED component skin temperature T _cthe slope declined;

3rd characterisitic parameter c of S2, calculating LED component _iwith the 4th characterisitic parameter c _o;

S3, according to formula input the energy conversion efficiency η under different electric current _w, predict the junction temperature temperature T of the LED component under any electric current _j, wherein, T _ofor constant junction temperature;

S4, according to formula P _heat=[1+ (c _tilnI+c _to) (T _j-T _o)-c _oexp (-c _ii)] P _d, input the junction temperature temperature T of the LED component under different electric current _j, predict the thermal power P of the LED component under any electric current _heat, wherein, P _dfor the electric power of LED component.

7. method according to claim 6, is characterized in that, described step S1 is specially:

S11, measurement LED component electric current I ₁under temperature coefficient c _t1, temperature coefficient c _t1for electric current I ₁lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S12, measurement LED component electric current I ₂under temperature coefficient c _t2, temperature coefficient c _t2for electric current I ₂lower energy dress changes efficiency eta _w-LED component skin temperature T _cthe slope of straight line;

S13, by electric current I ₁with temperature coefficient c _t1, electric current I ₂with temperature coefficient c _t2substitute into formula c respectively _t=c _tilnI+c _toin, calculate the first characterisitic parameter c _tiwith the second characterisitic parameter c _to.

8. method according to claim 7, is characterized in that, in described step S1,

Step S11 is specially:

Use constant current source I ₁driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₁energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₁invariable, be T in skin temperature _c2be I with drive current ₁the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₁under temperature coefficient c _t1;

Step S12 is specially:

Use constant current source I ₂driving LED device, is arranged to T by the skin temperature of LED component _c1, measuring in skin temperature is T _c1be I with drive current ₂energy conversion efficiency η under condition _w1; Secondly, the skin temperature changing LED component is T _c2, drive current maintains I ₂invariable, be T in skin temperature _c2be I with drive current ₂the energy conversion efficiency η of LED component is measured under condition _w2; This is measured two the point (T obtained _c1, η _w1) and (T _c2, η _w2) be placed on and change efficiency eta with energy dress _wfor the longitudinal axis and LED component skin temperature T _cfor in the coordinate system of transverse axis, and connect with straight line, the slope of this straight line is exactly electric current I ₂under temperature coefficient c _t2.

9. method according to claim 6, is characterized in that, described step S2 is specially:

S21, in electric current I ₁the energy conversion efficiency of lower measurement LED component be designated as

S22, in electric current I ₂the energy conversion efficiency of lower measurement LED component be designated as

S23, by electric current I ₁and energy conversion efficiency electric current I ₂and energy conversion efficiency substitute into respectively in, calculate the 3rd characterisitic parameter c of LED component _iwith the 4th characterisitic parameter c _o, wherein, be the junction temperature temperature of LED component be T _ounder the energy conversion efficiency of LED component.

10. method according to claim 6, is characterized in that, described step S2 also comprises:

According to T _c=T _j-R _jck _hp _dthe skin temperature of LED component is set, wherein, T _cfor the skin temperature of LED component, T _jfor the junction temperature temperature of LED component, T in step s 2 _j=T _o, R _jcfor the thermal resistance of LED component, k _hfor the heat rejection coefficient of LED component, P _dfor the electric power of LED component.