CN102595732B - LED (light-emitting diode) temperature control method and system based on PWM (pulse width modulation) - Google Patents
LED (light-emitting diode) temperature control method and system based on PWM (pulse width modulation) Download PDFInfo
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- CN102595732B CN102595732B CN201210045322.9A CN201210045322A CN102595732B CN 102595732 B CN102595732 B CN 102595732B CN 201210045322 A CN201210045322 A CN 201210045322A CN 102595732 B CN102595732 B CN 102595732B
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Abstract
The invention discloses an LED (light-emitting diode) temperature control method and system based on PWM (pulse width modulation). The method comprises the following steps: detecting voltage U1 of a photoresistor through a controller and figuring out the brightness of an LED; calculating the current total power consumption W1 of the LED according to PWM duty ratio d1, performing power consumption table lookup according to the W1, finding out the light efficiency eta 1 which needs to be achieved by the LED at the current W1, calculating the current light efficiency eta 2 according to the brightness of the LED and the current total power consumption W1, comparing the eta 1 with the eta 2, screening out points with the total power consumption W2 which is lower than W1 according to a temperature-light efficiency curve if the eta 2 is less than the eta 1, calculating PWM duty ratio d2 according to the total power consumption W2 and adjusting a PWM output signal according to the d2 so as to always control the temperature of a circuit of the LED in an appropriate range, prevent the temperature from being too high and affecting the light efficiency of the LED. According to the method disclosed by the invention, the LED can work in the appropriate temperature range, fully play the light efficiency and realize the optimal balance among the brightness of the LED, the light efficiency and the temperature. The LED temperature control system disclosed by the invention is simple in structure and low in cost.
Description
Technical field
The present invention relates to a kind of temperature control technology field of LED lighting apparatus, be specifically related to a kind of LED temperature-controlled process and system based on PWM.
Background technology
LED is because of advantages such as the life-span are long, efficiency is high, energy-conservation, and the application in lighting field is more and more extensive.But the life-span of LED and optical efficiency and working temperature have substantial connection, temperature exceedes after certain value, and its optical efficiency and life-span can decline rapidly.Due to the decline of optical efficiency, the brightness of LED declines, and more power consumption can change into heat energy and dissipate; If the LED of brightness-adjustable now increases electric current in order to increase brightness, can further increase its caloric value, not only do not have the object that increases brightness, can accelerate on the contrary the aging of LED.
At present, control temperature methods in LED circuit, generally to dispel the heat by increasing radiator, reduce passively the working temperature of LED, due to problems such as process Installation, the LED of different batches is difficult to ensure that the effect of its heat radiation is identical, even in same LED lighting apparatus, due to each LED the factor such as position, its radiating effect is also not necessarily identical; Or by regulating LED brightness to change caloric value, and this mode is difficult to be accepted by user.
At " a kind of power method and system that improves LED lamp " (application number 201010154632.5, open day on September 22nd, 2010, publication number CN101841956A) patent document in proposed to combine by radiator and temperature detection and control, ensureing that LED temperature is not the super upper limit in the situation that, strengthen immediate current as far as possible, thereby improve the power of LED as far as possible.This kind of method and apparatus also exists temperature to be difficult to the problem of Measurement accuracy and control.Meanwhile, the formation of the hardware device that the method needs is also more complicated, and cost is corresponding higher.
Summary of the invention
In order to solve the deficiency in above-mentioned technology, the invention provides a kind of LED temperature-controlled process and system based on PWM that can make LED work, give full play to its optical efficiency in suitable temperature range and can realize LED brightness and optical efficiency, temperature and reach optimum balance.
In order to reach foregoing invention object, the technical solution used in the present invention is: a kind of LED temperature-controlled process based on PWM is provided, it is characterized in that, comprise the following steps:
A, brightness detect the voltage U 1 of loop detection photo resistance or light-sensitive semiconductor element and voltage U 1 are outputed to AD converter and outputs to controller by AD converter again, are then calculated the brightness of LED according to voltage U 1 by controller; Or directly voltage U 1 is outputed to the controller that is built-in with AD converter, then calculated the brightness of LED by controller according to voltage U 1;
B, controller calculate the current total power consumption W1 of LED according to PWM duty ratio d1 in current control circuit, current total power consumption W1 is carried out power consumption by controller to table look-up, and finds out the optical efficiency η 1 that LED should reach in the time of current total power consumption W1;
The current total power consumption W1 of the LED that the brightness of the LED that c, controller calculate according to step a and step b calculate calculates the optical efficiency η 2 of LED in current system;
D, comparison η 1 and η 2, if η is 2 < η 1, controller is inquired about the temperature-luminous efficiency curve tables of data in controller according to η 2, a suite line that finds optical efficiency to equate with η 2 filters out the point that total power consumption is lower than current total power consumption W1 simultaneously in this suite line; If η 2=η 1, controller does not make any adjustments, and time delay a period of time is detected again;
If e finds the point described in steps d, controller calculates PWM duty ratio d2 according to the total power consumption W2 of this point, and adjusts according to duty ratio d2 the PWM output signal of controlling LED, and PWM output signal is outputed to drive circuit; If do not find the point described in steps d, controller does not make any adjustments, and time delay a period of time is detected again.
Described temperature-luminous efficiency curve is a suite line relevant to LED self character, and this curve comprises parameter optical efficiency, total power consumption, temperature, voltage, electric current.
A kind of LED temperature control system based on PWM, comprise that at least one drives loop, it is characterized in that: also comprise control circuit, described control circuit comprises that at least one brightness detects loop and a controller, described brightness detects loop and is connected with controller, and described controller is connected with driving loop.
Described control circuit also comprises an AD converter, and described AD converter is independently arranged in control circuit, and one end is detected loop with brightness and is connected, and the other end is connected with controller; Or described AD converter is to be directly integrated in controller.
It is a bridge-type bleeder circuit that described brightness detects loop, at least comprises a photo resistance or a light-sensitive semiconductor element, and the bleeder circuit at described photo resistance or light-sensitive semiconductor element place is connected with controller.
Described bridge-type bleeder circuit is by photo resistance or light-sensitive semiconductor element and three four arm electrical bridges that resistance forms.
Described controller is single-chip microcomputer.
Described controller is provided with at least one voltage detecting end and at least one pwm signal output.
In sum, LED temperature-controlled process and the system based on PWM provided by the present invention can make LED in suitable temperature range, work, give full play to its optical efficiency, and can realize LED brightness and optical efficiency, temperature reach optimum balance.LED temperature control system of the present invention is simple in structure, with low cost.
Brief description of the drawings
Fig. 1 is the control circuit figure in the embodiment of the present invention;
Fig. 2 is the flow chart of control method of the present invention.
Wherein, 1, photo resistance; 2, resistance; 3, be built-in with the controller of AD converter; 4, switching tube; 5, LED.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the invention will be further described:
As shown in Figure 1: a kind of LED temperature control system based on PWM, comprises that one drives loop, is characterized in that: also comprise control circuit, described control circuit detects loop and a controller 3 by a brightness, in described controller 3, is integrated with AD converter; Described brightness detects the voltage output end in loop and the voltage detecting end of controller 3 is connected, and described driving loop is connected with the pwm signal output of controller 3.
Described brightness detects loop and forms a four arm electrical bridge bleeder circuit by a photo resistance 1 and three resistance 2, and the bleeder circuit at photo resistance 1 place is connected with controller 3.
Described driving loop is made up of the switching tube 4 of LED5 and control LED5, and the negative electrode of described LED5 is connected with the collector electrode of switching tube 4, and the base stage of switching tube 4 is connected with the PWM output of controller 3, the grounded emitter of switching tube 4.Drive loop also can adopt other conventional structures, as adopted other switching devices such as metal-oxide-semiconductor, or the driving loop of employing and this driving loop structure antithesis etc.
Described controller 3 is single-chip microcomputer, and single-chip microcomputer is provided with a voltage detecting end and a pwm signal output.
As shown in Figure 2, a kind ofly it is characterized in that according to the control method of the temperature control system described in Fig. 1, comprise the following steps:
A, brightness detect loop and detect the voltage U 1 of photo resistance 1 and voltage U 1 outputed to the controller 3 that is built-in with AD converter, then calculated the brightness of LED5 by controller 3 according to voltage U 1;
B, controller 3 calculate the current total power consumption W1 of LED5 according to PWM duty ratio d1 in current control circuit, current total power consumption W1 is carried out power consumption by controller 3 to table look-up, and finds out the optical efficiency η 1 that LED5 should reach in the time of current total power consumption W1;
The current total power consumption W1 of the LED5 that the brightness of the LED5 that c, controller 3 calculate according to step a and step b calculate calculates the optical efficiency η 2 of LED5 in current system;
D, comparison η 1 and η 2, if η is 2 < η 1, controller 3 is inquired about the temperature-luminous efficiency curve tables of data in controller 3 according to η 2, a suite line that finds optical efficiency to equate with η 2 filters out the point that total power consumption is lower than current total power consumption W1 simultaneously in this suite line; If η 2=η 1, controller 3 does not make any adjustments, and time delay a period of time is detected again;
If e finds the point described in steps d, controller 3 calculates PWM duty ratio d2 according to the total power consumption W2 of this point, and adjust the PWM output signal of controlling LED5 according to duty ratio d2, and PWM output signal is outputed to drive circuit, thus the Kai Heguan of control switch pipe 4 driving LED 5; If do not find the point described in steps d, controller 3 does not make any adjustments, and time delay a period of time is detected again.
Described temperature-luminous efficiency curve is a suite line relevant to LED self character, and different LED has different characteristic curves, is obtained by test in early stage, and this curve comprises parameter optical efficiency, total power consumption, temperature, voltage, electric current.
In addition, detect the difference of loop and driving loop quantity according to brightness, the optical efficiency calculating according to the voltage detecting in step a has different control modes:
(1) if each LED unit has a brightness to detect loop and multiple drivings loop in LED temperature control system, the optical efficiency that the potentiometer being detected by brightness detection loop calculates will be controlled multiple drivings loop, i.e. one-to-many control simultaneously.
(2) if corresponding brightness detection loop respectively, the each driving loop in LED temperature control system in each LED unit, the many groups voltage detecting need be processed respectively, and calculate respectively driving loop corresponding to corresponding optical efficiency control, control one to one.
In the present embodiment, only have a brightness to detect loop and a driving loop, drive loop so the optical efficiency calculating is only controlled one, control one to one.
Although in conjunction with specific embodiments the specific embodiment of the present invention is described in detail, it is not the restriction to this patent protection range.In claims limited range, the various amendments that those skilled in the art can make without creative work or adjustment are still subject to the protection of this patent.
Claims (2)
1. the LED temperature-controlled process based on PWM, is characterized in that, comprises the following steps:
A, brightness detect the voltage U 1 of loop detection photo resistance or light-sensitive semiconductor element and voltage U 1 are outputed to AD converter and outputs to controller by AD converter again, are then calculated the brightness of LED according to voltage U 1 by controller; Or directly voltage U 1 is outputed to the controller that is built-in with AD converter, then calculated the brightness of LED by controller according to voltage U 1;
B, controller calculate the current total power consumption W1 of LED according to PWM duty ratio d1 in current control circuit, current total power consumption W1 is carried out power consumption by controller to table look-up, and finds out the optical efficiency η 1 that LED should reach in the time of current total power consumption W1;
The current total power consumption W1 of the LED that the brightness of the LED that c, controller calculate according to step a and step b calculate calculates the optical efficiency η 2 of LED in current system;
D, comparison η 1 and η 2, if η is 2 < η 1, controller is inquired about the temperature-luminous efficiency curve tables of data in controller according to η 2, a suite line that finds optical efficiency to equate with η 2 filters out the point that total power consumption is lower than current total power consumption W1 simultaneously in this suite line; If η 2=η 1, controller does not make any adjustments, and time delay a period of time is detected again; Temperature-luminous efficiency curve refers to that the optical efficiency of LED is with the relation curve of the variations in temperature of LED;
If e finds the point described in steps d, controller calculates PWM duty ratio d2 according to the total power consumption W2 of this point, and adjusts according to duty ratio d2 the PWM output signal of controlling LED, and PWM output signal is outputed to drive circuit; If do not find the point described in steps d, controller does not make any adjustments, and time delay a period of time is detected again.
2. the LED temperature-controlled process based on PWM according to claim 1, is characterized in that: described temperature-luminous efficiency curve is a suite line relevant to LED self character, and this curve comprises parameter optical efficiency, total power consumption, temperature, voltage, electric current.
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| CN201210045322.9A CN102595732B (en) | 2012-02-27 | 2012-02-27 | LED (light-emitting diode) temperature control method and system based on PWM (pulse width modulation) |
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| CN201210045322.9A CN102595732B (en) | 2012-02-27 | 2012-02-27 | LED (light-emitting diode) temperature control method and system based on PWM (pulse width modulation) |
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| CN102883506B (en) * | 2012-09-21 | 2014-10-29 | 东南大学 | Method for dynamically controlling temperature of central area of array light emitting diode (LED) lighting lamp |
| CN103781228A (en) * | 2012-10-24 | 2014-05-07 | 深圳市鑫田威尔科技有限公司 | LED industrial and mineral lamp and circuit control method thereof |
| CN103458575B (en) * | 2013-08-22 | 2016-05-18 | 广西奥顺仪器有限公司 | Great power LED digital linear light-dimming method |
| CN105050263A (en) * | 2015-07-15 | 2015-11-11 | 广东融能科技有限公司 | Time-sharing automatic dimming system and method for light-emitting diode (LED) street lamp |
| US9763305B1 (en) * | 2016-04-15 | 2017-09-12 | Infineon Technologies Austria Ag | Temperature protection circuit for light-emitting diodes |
| CN107027213B (en) * | 2017-03-06 | 2018-11-30 | 广东德洛斯照明工业有限公司 | A kind of intelligence constant luminance output control method |
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| JP4805026B2 (en) * | 2006-05-29 | 2011-11-02 | シャープ株式会社 | LIGHT EMITTING DEVICE, DISPLAY DEVICE, AND LIGHT EMITTING DEVICE CONTROL METHOD |
| CN100583215C (en) * | 2008-08-20 | 2010-01-20 | 青岛海信电器股份有限公司 | LED backlight module and its temperature control method |
| CN101749567B (en) * | 2008-12-16 | 2012-03-28 | 比亚迪股份有限公司 | LED system |
| CN101841956A (en) * | 2010-04-23 | 2010-09-22 | 郭家辰 | Method and system for improving power of LED lamp |
| CN102036443A (en) * | 2010-10-14 | 2011-04-27 | 青岛锐晶光电科技有限公司 | Light-emitting diode (LED) temperature detecting and controlling method |
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