CN103747587A - LED (Light Emitting Diode) lamp radiator temperature online self-adaptation control circuit and method - Google Patents

LED (Light Emitting Diode) lamp radiator temperature online self-adaptation control circuit and method Download PDF

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Publication number
CN103747587A
CN103747587A CN201410018278.1A CN201410018278A CN103747587A CN 103747587 A CN103747587 A CN 103747587A CN 201410018278 A CN201410018278 A CN 201410018278A CN 103747587 A CN103747587 A CN 103747587A
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temperature
radiator
led
resistance
control circuit
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CN103747587B (en
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景占荣
张玥
羊彦
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Northwestern Polytechnical University
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Northwestern Polytechnical University
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Abstract

The invention discloses an LED (Light Emitting Diode) lamp radiator temperature online self-adaptation control circuit and method. According to the current value and the rate of change of an LED lamp radiator, the input power of an LED lamp is adjusted online in a self-adaptation way, the slippage of the dissipation capacity of the radiator caused by the rise of environment temperature is equivalent to the slippage of the input power; no matter how the environment temperature changes, the temperature of the radiator can reach balanced in a prescribed limit, an LED device is prevented from being damaged by high temperature, and the reliability of the LED lamp in a high-temperature environment is improved. The self-adaptation control circuit and method are particularly suitable for occasions with larger environment temperature changes; a little hardware is used by the technology, the implementation mode is simple, and the popularization is facilitated; compared with the prior art, the method has the advantages that the reliability is improved, the cost is reduced, and the usable range is enlarged.

Description

A kind of LED lamp radiator temperature online adaptation control circuit and method
Technical field
The present invention relates to a kind of LED lamp radiator temperature online adaptation control circuit and method, particularly in sharply rising situation of ambient temperature and can maintain the method for the temperature online adaptive control of the normal work of LED lamp.
Background technology
LED light fixture, the particularly operating ambient temperature of LED street lamp change very greatly, and winter may be below minus 20 degrees, and summer is up to more than 60 degree; The larger temperature difference has been brought trouble to heat dissipation design.If by high ambient temperature design, the weight of LED lamp is increased, cost is soaring, is also the bottleneck that this green illumination product is introduced to the market; Otherwise, remain on the integrity problem of working under high ambient conditions and be difficult to solve.
At present, the approach addressing this problem mainly contains two classes; One class is that the structure of radiator is optimized to design and development, improves the radiating condition of LED light fixture, but after product approval, can not carry out self adaptation adjustment to the variation of operational environment and condition of work.Another kind of mode is the method for in running, radiator temperature being monitored and being controlled, and is also the focus of studying at present.Fairly simple method is the method for overheated power-off protection; a temperature sensor is installed on LED lamp radiator; when detecting that the temperature of radiator exceedes threshold limit value; by the hardware circuit being connected with this temperature sensor, turn-off LED driver; cut off the electricity supply, in order to avoid light-emitting diode is burnt under high-temperature condition.But the drawback of this method is to cause illumination to interrupt, and even causes related accident.As document < < illumination of high-power semiconductor driving power design > > (Changchun Polytechnic Univ.'s master thesis, 2011) in a kind of self-adaptation control method has been proposed, a temperature sensor is installed on LED lamp radiator, and its output is connected with single-chip microcomputer, when single-chip microcomputer detects that the temperature of radiator exceedes permissible value, by the input power of its PWM output control LED lamp, reduce caloric value, make the temperature of LED lamp radiator recover normal.The control effect of the method is better, but the problem of having brought control system complexity, cost of manufacture to increase is not particularly suitable for widely used small-power green lighting system, and the scope of application is very limited.
Summary of the invention
For fear of the deficiencies in the prior art part, the present invention proposes a kind of LED lamp radiator temperature online adaptation control circuit and method, this circuit and method are according to LED lamp radiator currency and rate of change thereof, online adaptive is adjusted LED lamp input power, and make the slippage of radiator dissipation capabilities that causes because of the rising of ambient temperature suitable with the slippage of input power, thereby radiator temperature is remained in safe range, avoid high temperature to damage LED device, be particularly suitable for the occasion that variation of ambient temperature is larger.
The technical solution adopted for the present invention to solve the technical problems is: comprise temperature sensor D 1, gradient regulating resistance R 1, divider resistance R 2, load circuit constant current controlling resistance R 3, it is characterized in that: V 1to control LED light fixture input voltage, temperature sensor D 1be and the LED diode of LED light fixture same model gradient regulating resistance R 1for changing V 1the slope of curve declining with temperature rise, R 2for divider resistance, the size of its partial pressure value depends on R 3, be R 3pressure drop V 3higher limit, R 3for load circuit constant current controlling resistance;
When ambient temperature rises, due to temperature sensor D 1negative temperature characteristic, make V fTdecline; Due to R 1regulating action, V 1fall off rate be restricted to △ V 1/ △ T ≈ δ;
Due to V 1be used for controlling LED light fixture input power, make the heat dissipation amount P of LED chip dalso by δ, reduce; Meanwhile, due to the rising of ambient temperature, the dissipation capabilities of radiator declines, and fall off rate is △ P d/ △ T=η;
The condition of selecting due to element in circuit is to ensure that δ=η is prerequisite, and the slippage of radiator dissipation capabilities is suitable with the slippage of input power; Due to the guarantee of δ=η condition, the temperature on radiator reaches balance in prescribed limit.
Beneficial effect
A kind of LED lamp radiator temperature online adaptation control circuit and method that the present invention proposes, it is according to LED lamp radiator currency and rate of change thereof, online adaptive is adjusted LED lamp input power, and make the slippage of radiator dissipation capabilities that causes because of the rising of ambient temperature suitable with the slippage of input power, no matter the variation of ambient temperature how, temperature on radiator all can reach balance in prescribed limit, avoid high temperature to damage LED device, thereby improved the reliability of LED lamp in hot environment.Control circuit of the present invention and method are particularly suitable for the occasion that variation of ambient temperature is larger; Because this technology is only used and is used a small amount of hardware, implement simply, be convenient to promote; And compared with art methods, improved reliability, reduced cost, expanded the scope of application.
Accompanying drawing explanation
Below in conjunction with drawings and embodiments, a kind of LED lamp radiator temperature online adaptation control circuit of the present invention and method are described in further detail.
Fig. 1 is the temperature online self adaptation Circuit tuning schematic diagram of LED lamp.
Embodiment
The present embodiment is a kind of LED lamp radiator temperature online adaptation control circuit and method.
A.. the theoretical foundation that the present invention proposes
During LED work, because the existence of thermal resistance, the thermometer of PN junction is shown:
T J=T A+R θP D
In formula, T jfor PN junction temperature, T afor ambient temperature,
R θfor PN junction is to the thermal resistance of environment, P dfor heat dissipation;
Wherein, PN junction temperature T jbe approximately radiator temperature; For LED, 3%~5% of input electric power converts light energy output to, and remainder is dissipated in device with form of heat, therefore can be similar to the product representation heat dissipation P with forward voltage drop and input current d, can not bring very large deviation to experimental study.
For fixing device heat dissipation structure, be connected with electrical equipment, chip is certain to the thermal resistance of environment, like this, in the situation that input power is constant, can be similar to and thinks that the change amount of ambient temperature just equals the change value of tube core PN junction temperature.
The rising of ambient temperature affects major embodiment both ways to LED performance parameter:
First LED two ends forward voltage drop dullness reduces; If selected with the LED diode of light fixture same model as temperature sensor D 1, to guarantee the consistency of thermal parameter in wide temperature range, D 1pN junction voltage V fTcan approximate representation be:
V FT=V F0+K(T-T 0) ⑵
V in formula fTambient temperature temperature sensor D while being T 1the voltage at two ends, V f0that ambient temperature is T 0time D 1the voltage at two ends, K is that voltage varies with temperature coefficient, is negative value.For example, luminescent material is that the K value of InGaN, the backing material LED chip that is SiC is :-2.66 (mV/ degree).
Its two, LED lamp heat-sinking capability decline; By (1) formula, had:
P D=(T J-T A)/R θ
Obviously, for given T j, R θvalue, works as T aduring rising, allow heat dissipation power P ddecline thereupon.
By formula (2), (3) can find out: when ambient temperature raises, not only make the heat dissipation ability of LED chip decline, also make its PN junction pressure drop decline, the two all further makes LED lamp thermal environment worsen.The present invention be directed to this demand and put forward, by the adjustment of online adaptive dissipation power, radiator temperature is remained in allowed band.
B.. the specific embodiment of the invention
Consult Fig. 1, the each components and parts effect of the present invention and calculation method of parameters are as follows:
(1) temperature sensor D 1, be and the LED diode of LED light fixture same model, to guarantee the consistency of thermal parameter in wide temperature range.D 1there is negative temperature characteristic, when ambient temperature rises, its PN junction voltage V fTwill decline.
(2) gradient regulating resistance R 1, be used for changing V 1the slope of curve declining with temperature rise, it is core of the present invention.
V 1temperature variant rate of change δ is:
V 1=V 2+V FT=I 0R 1+V FT 0+K(T-T 0) ⑷
By (4) formula, obtained:
△V 1/△T≈KT/(V 2+V FT 0)=δ ⑸
In addition, along with the warm variation of ring, the dissipation rate η that can be obtained radiator by (3) formula is expressed as:
△P D/△T=△T/R θ=η ⑹
Make ambient temperature raise time radiator temperature constant, need meet δ= η, can obtain:
KT/(V 2+V FT 0)=△T/R θ
That is: V 2=I 0r 1=V ft 0+ KR θ;
So:
R 1=(V FT 0+KR θ)/I 0
Formula (7) in, V f, T 0, K, R θ, I 0be known quantity.
(3) divider resistance R 2, the size of its partial pressure value depends on R 3, be R 3pressure drop V 3higher limit;
If R 2=r 1+ r 2, by requirement of the present invention, r 1, r 2selection need meet following condition;
Divide pressure request: i.e. r 1, r 2selection need meet V 1r 1/ (r 1+ r 2)=I 1r 3, to make circuit play the effect of temperature protection and constant current simultaneously.
Streaming request: due to I 0constant-current source output, for fear of R 2to D 1-R 1the shunting of branch road and affect precision, must make R 2resistance enough large, as far as possible little to the shunting of constant-current source, be about 0.02I 0.
(4) load circuit constant current controlling resistance R 3, the present invention to the requirement of this resistance is: should make R 3it is minimum that dissipation power reaches, and also will make the V detecting 3(I 1r 3) value meets anti-interference, the required precision of voltage comparator input, is generally tens~hundreds of milliohm, the size of apparent load electric current is determined.
(5) the selection of other element is selected by general circuit design principle, constant-current source output current I 0be about D 11/10 of rated current; IC1, IC2, IC3 select general MOS device; Power tube is pressed load and is selected; Triangular-wave generator selects ready-made circuit.
Control procedure:
Control circuit of the present invention and method, when ambient temperature rises, due to temperature sensor D 1negative temperature characteristic, make V fTdecline.But, due to R 1regulating action, V 1fall off rate be restricted to △ V 1/ △ T ≈ δ.
Due to V 1be used for controlling LED light fixture input power, make the heat dissipation amount P of LED chip dalso by δ, reduce; On the other hand, due to the rising of ambient temperature, the dissipation capabilities of radiator also declines, and fall off rate is △ P d/ △ T= η.
The condition of selecting due to element in circuit is to ensure that δ=η is prerequisite, and the slippage of radiator dissipation capabilities is suitable with the slippage of input power; Therefore,, no matter the variation of ambient temperature how, due to the guarantee of δ=η condition, the temperature on radiator all can reach balance in prescribed limit, thereby has improved the reliability of LED lamp in hot environment.

Claims (1)

1. LED lamp radiator temperature online adaptation control circuit and a method, comprises temperature sensor D 1, gradient regulating resistance R 1, divider resistance R 2, load circuit constant current controlling resistance R 3, it is characterized in that: V 1to control LED light fixture input voltage, temperature sensor D 1be and the LED diode of LED light fixture same model gradient regulating resistance R 1for changing V 1the slope of curve declining with temperature rise, R 2for divider resistance, the size of its partial pressure value depends on R 3, be R 3pressure drop V 3higher limit, R 3for load circuit constant current controlling resistance;
When ambient temperature rises, due to temperature sensor D 1negative temperature characteristic, make V fTdecline; Due to R 1regulating action, V 1fall off rate be restricted to △ V 1/ △ T ≈ δ;
Due to V 1be used for controlling LED light fixture input power, make the heat dissipation amount P of LED chip dalso by δ, reduce; Meanwhile, due to the rising of ambient temperature, the dissipation capabilities of radiator declines, and fall off rate is △ P d/ △ T=η;
The condition of selecting due to element in circuit is to ensure that δ=η is prerequisite, and the slippage of radiator dissipation capabilities is suitable with the slippage of input power; Due to the guarantee of δ=η condition, the temperature on radiator reaches balance in prescribed limit.
CN201410018278.1A 2014-01-15 2014-01-15 A kind of LED lamp radiator temperature online adaptation control circuit Expired - Fee Related CN103747587B (en)

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CN105142272A (en) * 2015-08-23 2015-12-09 合肥艾斯克光电科技有限责任公司 Cooling failure processing method for light emitting diode (LED) lamp
CN105163428A (en) * 2015-08-23 2015-12-16 合肥艾斯克光电科技有限责任公司 Radiating control device of light-emitting diode (LED) lamp
CN108075632A (en) * 2017-12-28 2018-05-25 深圳市创新微源半导体有限公司 A kind of self-adaptive temperature protects circuit
CN108120918A (en) * 2017-08-07 2018-06-05 鸿秦(北京)科技有限公司 A kind of chip makes physical destroys online test method and device on effect circuit board
CN113803654B (en) * 2021-09-18 2024-03-22 厦门东昂科技股份有限公司 High heat dissipation lamp structure using LED lamp

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105142272A (en) * 2015-08-23 2015-12-09 合肥艾斯克光电科技有限责任公司 Cooling failure processing method for light emitting diode (LED) lamp
CN105163428A (en) * 2015-08-23 2015-12-16 合肥艾斯克光电科技有限责任公司 Radiating control device of light-emitting diode (LED) lamp
CN108120918A (en) * 2017-08-07 2018-06-05 鸿秦(北京)科技有限公司 A kind of chip makes physical destroys online test method and device on effect circuit board
CN108075632A (en) * 2017-12-28 2018-05-25 深圳市创新微源半导体有限公司 A kind of self-adaptive temperature protects circuit
CN113803654B (en) * 2021-09-18 2024-03-22 厦门东昂科技股份有限公司 High heat dissipation lamp structure using LED lamp

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