CN105578642A

CN105578642A - Constant-power color matching algorithm applied to LED light fixture

Info

Publication number: CN105578642A
Application number: CN201510948381.0A
Authority: CN
Inventors: 陈志曼
Original assignee: Guangzhou Yajiang Photoelectric Equipment Co Ltd
Current assignee: Guangzhou Yajiang Photoelectric Equipment Co Ltd
Priority date: 2015-12-17
Filing date: 2015-12-17
Publication date: 2016-05-11
Anticipated expiration: 2035-12-17
Also published as: CN105578642B

Abstract

The invention discloses a constant-power color matching algorithm applied to an LED light fixture. The algorithm comprises the following steps: consuming that the LED light fixture is provided with a lamp bead in n colors, calculating actually consumed maximum power W1 to Wn in case of single-color total brightness of the bead, and measuring maximum apparent power Pw of the light fixture; calculating efficiency eta of the bead in consuming power, wherein eta=(w1+w2+...wn)/Pw; setting allowed rated maximum power Mw of the bead, wherein the Mw<Pw; setting that a PWM duty ratio of each color is N1 to Nn, wherein the value scope of each PWM duty ratio ranges from 0 to 100%; and calculating current apparent power Cw in case of a different-color mixing ratio, wherein Cw=(N1*w1+N2*w2+N3*w3+Nn*wn)/eta, a power factor theta (0<theta<=1), theta=Mw/Cw, and an actually output duty ratio of each color is N1*theta, N2*theta, N3*theta and Nn*theta. In case of light modulation, the brightness ratio is adjusted according to the current color mixing ratio, the brightness is changed, and the color performance of color mixing is also ensured.

Description

A kind of invariable power matching algorithm applied in LED lamp

Technical field

The present invention relates to the light-dimming method in LED lamp, especially apply to the invariable power matching algorithm in the control of multiple color colour mixture.

Background technology

Pulse width modulation (PWM, Pulse-WidthModulation), also referred to as pulse-width modulation, pulse width modulation (PWM) is that one carries out digitally coded method to analog signal level.By the use of high-resolution counter, modulated being used for of the duty ratio of square wave is encoded to the level of a physical simulation signal.Pwm signal remains numeral, because in given any moment, expires the direct current supply of amplitude or has completely (ON), or completely without (OFF).Voltage or current source are added to fictitious load with the repetition pulse sequence of one logical (ON) or disconnected (OFF) to get on.Namely be namely direct current supply when being added in load time logical, be that power supply is when being disconnected time disconnected.As long as bandwidth is enough, any analogue value can use PWM to encode.

Nearly all commercially available single-chip microcomputer has PWM module function, and microcontroller all includes PWM controller.As long as be applied in the light modulation of LED by PWM technology, just can be controlled the brightness of each color of LED lamp by the PWM duty ratio controlling each color, the luminance mix of different colours will produce different brightness ratios, and often kind of brightness has different LED lamplight.

According to trichromatic principle, when the ratio of ruddiness and green glow and blue light is the same, mixed light is out exactly white light, as 100 parts of ruddiness: 100 parts of green glows: 100 parts of blue light=100 part white lights, so ruddiness, the brightness ratio of green glow and blue light is 100:100:100, color colour mixture ratio is 1:1:1, the in like manner ruddiness of 1 part: 1 part of green glow: the white light of 1 part of blue light=1 part, color colour mixture is than not changing, still or white light, just white brightness is dimmed according to brightness ratio ratio, and invariable power matching algorithm, realize exactly in specified power bracket, ensure that each color colour mixture of LED lamp remains " white light " than constant effect, automatic adjustment brightness ratio.

Summary of the invention

Technical problem to be solved by this invention uses a kind of invariable power matching algorithm to be applied in the light fixture PWM light regulating technology of LED, in specified power bracket, the color colour mixture ratio of LED lamp is exactly brightness ratio, when beyond specified power, LED lamp can keep being work under specified power always, ensures that each color colour mixture ratio remains unchanged by the brightness value adjusting each color.

For solving the problems of the technologies described above, technical scheme of the present invention is: a kind of PWM invariable power matching algorithm applied in LED lamp

Suppose that LED lamp is provided with the lamp pearl of n kind color, calculate the maximum power w1 ~ wn of the monochromatic entirely bright actual consumption of lamp pearl,

Measure the maximum apparent power Pw of light fixture;

Calculate the efficiency eta of lamp pearl consumed power, η=(w1+w2+ ... wn)/Pw;

Setting light fixture allows rated maximum power Mw, Mw<Pw;

If each color PWM duty ratio is N1 ~ Nn, each PWM duty ratio number range 0 ~ 100%;

Calculate the current apparent power Cw that different colours mixes ratio;

Ｃw=(N1*w1+N2*w2+N3*w3+Nn*wn)/η；

Power factor (PF) θ (0 < θ≤1), θ=Mw/Cw, the duty ratio of the actual output of each color is N1* θ, N2* θ, N3* θ, Nn* θ.

In the present invention, the duty ratio of often kind of color is all multiplied by an identical definite value and can adjusts brightness ratio, because each colour brightness ratio remains unchanged, also ensure that the chromaticity of colour mixture.

The beneficial effect that the present invention is compared with prior art brought is:

The duty ratio of often kind of color is all multiplied by an identical definite value, when ensure that the colour mixture of each color than changing its brightness ratio constant to change the brightness of mixed light, firm power algorithm also can allow light fixture constant in specified power bracket simultaneously, can not exceed the load of power supply.

Embodiment:

As the LED Colour lamp of four looks, four looks are RGBW, individually measure light fixture each color complete bright time electric current I and voltage U, according to ohm formula: P=UI, the maximum power calculating the monochromatic entirely bright actual consumption of lamp pearl is respectively Rw, Gw, Bw, Ww, the gross power of whole lamp is Pw, then the power efficiency of the consumption of lamp pearl than η is:

η=（Ｒw+Ｇw+Ｂw+Ｗw）/Ｐw；

During light modulation, if the duty ratio (0 ~ 100%) of each color of RGBW is respectively RN, GN, BN, WN, then each color is RN*Rw, GN*Gw, BN*Bw, WN*Ww according to the actual power of different duty ratio consumption; Then current apparent power Cw can be calculated:

Ｃw=(ＲN*Ｒw+ＧN*Ｇw+ＢN*Ｂw+ＷN*Ｗw)/η

Set a specified performance number Mw(Mw<Pw), this performance number is exactly for setting the maximum performance number of light fixture, and when the actual power of light fixture is greater than Mw, actual performance number also constant maintenance is Mw;

Then, introduce parameter: a power factor (PF) θ (0 < θ≤1) again, for adjusting brightness ratio according to current colour mixture ratio, θ value carrys out value according to whether exceeding power-handling capability Mw, and when the power Cw of reality is less than rated power Mw, θ value perseverance is 1, ensure directly to export by Power Limitation in specified power bracket, and exceeded rated power and just carry out containing according to a ratio value later, so, θ value can be tried to achieve:

θ＝Ｍw/Ｃw；

Finally, the duty ratio of the actual output of each color is RN* θ, GN* θ, BN* θ, WN* θ, the duty ratio of often kind of color is all multiplied by an identical definite value, thus according to current colour mixture than adjustment brightness ratio, changes brightness but in turn ensure that the chromaticity of colour mixture.

Experimental example: a RGBW tetra-colored lights tool, maximum rated power requires 50W, when the PWM duty ratio of R, G, B, W is 100%, corresponding each color power R look 18W, G look 25W, B look 27W, W look 30W, during two kinds of blend of colors: R+G power 43W, R+W power 48W, B+W power 57W, R+G+W power 70W, G+B+W power 82W, R+G+B+W power 100W.Target call: light fixture 1, how could be allowed to keep monochrome the brightest, or two kinds of color work are to the brightest; 2, when two or more color colour mixture, gross power was both no more than 50W, can guarantee that again the colour mixture ratio of two or more color can not change.

Assuming that color PWM duty ratio be all 0 ~ 255 change, brightness and PWM duty ratio strictly proportional, LED consumed power and PWM duty ratio proportional;

When power is no more than power-handling capability, PWM duty ratio is exactly colour brightness, and PWM duty ratio is exactly colour mixture proportioning.When exceeding maximum rated power, during two kinds or more color colour mixtures, power constant maximum rating is constant, and colour mixture is distributed with the ratio of each color PWM duty ratio, and now color PWM duty ratio does not represent brightness, only represents colour mixture proportioning; Such as current R look PWM duty ratio is 255, G look PWM duty ratio is 255, power is 43W, when B look will be added, along with B look PWM duty ratio increases, power increases, and when B look PWM duty ratio reaches 66, power reaches rated value 50W, and now the ratio of the PWM duty ratio of RGB equals colour mixture proportioning value and equals brightness ratio and equal 255:255:100; When B look PWM duty ratio reaches 200, gross power or 50W, the ratio of the PWM duty ratio of RGB changes, but colour mixture proportioning value is also 255:255:200, but brightness ratio is 255* θ: 255* θ: 200* θ, and the value of θ (0 < θ≤1) is exactly the core in invariable power algorithm.

Claims

1. apply to the invariable power matching algorithm in LED lamp, it is characterized in that:

suppose that LED lamp is provided with the lamp pearl of n kind color, calculate the maximum power W1 ~ Wn of the monochromatic entirely bright actual consumption of lamp pearl,

measure the maximum apparent power Pw of light fixture;

calculate the efficiency eta of lamp pearl consumed power, η=(w1+w2+ ... wn)/Pw;

setting light fixture allows rated maximum power Mw, Mw<Pw;

if each color PWM duty ratio is N1 ~ Nn, each PWM duty ratio number range 0 ~ 100%;

calculate the current apparent power Cw that different colours mixes ratio;

Ｃw=(N1*w1+N2*w2+N3*w3+Nn*wn)/η；

power factor (PF) θ (0 < θ≤1), θ=Mw/Cw, the duty ratio of the actual output of each color is N1* θ, N2* θ, N3* θ, Nn* θ.

2. a kind of invariable power matching algorithm applied in LED lamp according to claim 1, it is characterized in that: individually measure light fixture each color complete bright time electric current I and voltage U, according to ohm formula: P=UI, calculate the maximum power of each color actual consumption respectively.

3. a kind of PWM invariable power matching algorithm applied in LED lamp according to claim 1, is characterized in that: LED lamp need set specified performance number.

4. a kind of invariable power matching algorithm applied in LED lamp according to claim 1, is characterized in that: this LED lamp needs the color lamp pearl of more than three kinds, and shades of colour power addition summation is greater than rated output power.