CN114280365A - Flicker-limited LED lamp inter-harmonic tolerance level estimation method - Google Patents
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Abstract
The invention relates to a flicker-limited LED lamp inter-harmonic tolerance level estimation method, which comprises the steps of testing different frequency inter-harmonics with constant amplitude and corresponding illuminance variation data, then carrying out frequency domain analysis on the collected data, and calculating the transmission coefficient of the relative variation of the LED lamp electricity and light corresponding to each inter-harmonic frequency; taking an incandescent lamp as a reference, and obtaining a conversion coefficient of the LED lamp relative to the incandescent lamp by solving a transmission coefficient ratio of the incandescent lamp to the corresponding frequency of the LED lamp; and finally, calculating the inter-harmonic content corresponding to the incandescent lamp under the flicker limit value condition by using the transfer function of the visual perception weighting filter based on the incandescent lamp, and multiplying the inter-harmonic content by the conversion coefficient of the corresponding frequency to calculate the flicker-limited LED lamp inter-harmonic tolerance level. The method has low use cost.
Description
Technical Field
The invention relates to the technical field of LED lamp performance parameter measurement, in particular to a flicker-limited estimation method for inter-harmonic tolerance level of an LED lamp.
Background
The voltage fluctuation caused by the inter-harmonic wave in the power grid can cause the change of the light brightness, thereby causing the contraction and expansion of the pupils of human eyes. If the light changes frequently, fatigue of iris muscles is caused in a short time, thereby causing unpleasant dysphoria or fatigue. Flicker quantifies the degree of influence of light changes on human visual perception. The flicker measurement model specified by IEC 61000-4-15 is established on the basis of the test results of a 60W tungsten filament incandescent lamp at 120V/60Hz and 230V/50Hz, and depends on the parameters of the incandescent lamp. The LED lamp and the incandescent lamp have different light emitting principles, so the existing flicker measurement model is not suitable for the LED lamp. Under the background that the LED lamp is widely applied, the flicker limit value is taken as a constraint to quantify the tolerance level of the inter-harmonic wave of the LED lamp.
At present, inter-harmonic levels of LED lamps under flicker limitation are obtained mainly by a method of repeatedly adjusting inter-harmonic amplitudes with different frequencies in an inter-harmonic-luminous flux-flicker test system to approach flicker limitation values, but the diversity of performance parameters of the LED lamps such as a driving power supply, color temperature and power inevitably brings the difference of flicker effects of the LED lamps, and the inter-harmonic level difference is obvious. Under the background, the method has the defect of lacking a referable approximate initial value, the complexity of the test steps and the complexity of data analysis are greatly increased, and the precision of the measurement result is limited by the minimum adjustment step length of the amplitude of the programmable power supply, so that the method is not beneficial to large-area popularization.
Disclosure of Invention
The invention aims to provide a flicker-limited LED lamp inter-harmonic tolerance level estimation method so as to reduce flicker-limited LED lamp inter-harmonic tolerance level estimation cost.
The technical scheme of the invention is as follows:
a method of estimating flicker-limited LED lamp inter-harmonic tolerance levels, comprising the steps of:
exciting the LED lamp to emit light by using an excitation voltage, and measuring the illuminance, wherein the excitation voltage is formed by a fundamental voltage and a frequency fIHIs mixed with the inter-harmonic voltage of frequency fIHInter-harmonic voltage excited light flicker frequency of
fM＝|fIH-h×f1| (1)
In the formula (f)1Is the fundamental voltage frequency, h being closest to fIHH 1,3,5, …, fIH≠h×f1；
Carrying out frequency domain analysis on the excitation voltage to obtain a fundamental voltage amplitude U1Frequency of fIHInter-harmonic amplitude U (f)IH) Analyzing the illuminance in frequency domain to obtain DC component L of the illuminanceDCAnd a frequency of fMIlluminance amplitude L (f)M) Then the relative change transmission coefficient of electricity and light of the LED lamp
Obtaining the relative change transmission coefficient G of electricity and light of the incandescent lamplamp,ref(fIH) Wherein the rated voltage of the incandescent lamp is equal to the rated voltage of the LED lamp, the rated frequency of the incandescent lamp is equal to the rated frequency of the LED lamp, and the conversion coefficient of the LED lamp relative to the incandescent lamp is obtained
Obtaining a short-time flicker limit value PstWhen the frequency is 1, the interharmonic content of the incandescent lamp
In the formula, Gw(fIH) Weighting coefficients for the perceptibility of said incandescent lamp;
the inter-harmonic tolerance level of the LED lamp is
Preferably, the algorithm of the frequency domain analysis is a fast fourier transform algorithm.
Preferably, the fundamental voltage is an alternating current determined by the rated voltage and the rated frequency of the LED lamp.
The invention has the beneficial effects that:
1. the LED lamp is excited by using an incandescent lamp as a reference, and the light intensity is measured, so that the inter-harmonic tolerance level of the LED lamp can be obtained. The flicker-limited estimation method for the inter-lamp harmonic tolerance level of the LED lamp has low application cost. The invention can provide reference basis for LED lamp type selection, driving design and standard formulation of different application scenes.
Drawings
FIG. 1 is a diagram of time-frequency domain for synchronously testing 45Hz inter-harmonics of constant amplitude and corresponding LED illuminance changes according to an embodiment of the present invention;
FIG. 2 is a diagram of a transfer coefficient of relative change between electric power and light of an LED lamp according to an embodiment of the present invention;
FIG. 3 is a diagram of the relative change transfer coefficient of the electric power and the light of the incandescent lamp provided by the embodiment of the invention;
FIG. 4 is a graph of the conversion coefficient of an LED lamp versus an incandescent lamp provided by an embodiment of the present invention;
FIG. 5 is a graph of the inter-harmonic content levels for a flicker limited incandescent lamp and an LED lamp according to an embodiment of the present invention.
Detailed Description
The present invention is described below in terms of embodiments in conjunction with the accompanying drawings to assist those skilled in the art in understanding and implementing the present invention. Unless otherwise indicated, the following embodiments and technical terms therein should not be understood to depart from the background of the technical knowledge in the technical field.
A method of estimating flicker-limited LED lamp inter-harmonic tolerance levels, comprising the steps of:
The function of each component of the interharmonic-illuminance testing system is as follows:
(1) programmable power supply: for outputting a set inter-harmonic voltage, i.e. outputting a "fundamental + constant inter-harmonic voltage at a set frequency".
(2) Shading the box body: the closed space for placing the LED lamp to be tested and the illuminance sensor has the capabilities of isolating external light change and eliminating irregular reflection interference inside, and can be realized by adopting a box body with the inner wall uniformly covered with black light absorption flannelette and the length of 0.7m multiplied by 1.0m multiplied by the height.
(3) Illuminance sensor: and testing the change of the LED lamp light brightness caused by the inter-harmonic voltage to simulate the light change reaction seen by human eyes.
(4) A data acquisition device: the device has a multi-channel data synchronous acquisition and recording function, records the output inter-harmonic voltage of the programmable power supply and illuminance data tested by the illuminance sensor, and has a sampling frequency not lower than 12.8 kHz.
(5) Testing the auxiliary parts: the LED lamp clamp comprises a test signal transmission line, an LED lamp clamp, a voltage line and the like.
During specific testing, the LED lamp to be tested is fixed in the middle of the shading box body by using the clamp, the illuminance sensor is horizontally placed right below the LED lamp to be tested, and the distance between the LED lamp to be tested and the illuminance sensor is always maintained at 0.5 m; then setting the illuminance sensor at a proper range, then closing the shading box body, starting the programmable power supply, controlling the programmable power supply to generate 230V and 50Hz fundamental wave voltages, overlapping inter-harmonics with the duration not less than 1s and the constant content (5 percent recommended) at the interval of 1Hz frequency sweep, and then synchronously recording the inter-harmonic voltage and illuminance change data by using the data acquisition device.
And 2, performing frequency domain analysis on the acquired data by adopting fast Fourier transform, and calculating the electric and light relative change transfer coefficients of the LED lamp corresponding to each inter-harmonic frequency.
The process of the step specifically comprises the following steps:
(1) for synchronous measurement at frequency fIHThe inter-harmonic voltage and the corresponding illuminance change data are respectively subjected to Fast Fourier Transform (FFT) by taking 50 cycles as analysis intervals to obtain fundamental voltage amplitude U1Frequency of fIHInter-harmonic amplitude U (f)IH) And a DC component L of illuminanceDCAnd a frequency of fMIlluminance amplitude L (f)M)，fIHAnd fMThe relationship satisfies the relationship of the formula (5).
fM＝|fIH-h×f1| (5)
In the formula: f. of1Is the fundamental voltage frequency; h is the closest to fIHH 1,3,5, …, fIH≠h×f1Thus f isM＜50Hz。
(2) Calculating the electric and light relative change transfer coefficient G of the LED lamp corresponding to each inter-harmonic frequency according to the ratio of the relative change of the illuminance to the inter-harmonic voltage contentLED(fIH) As shown in formula (6).
In the formula:
is the frequency fIHThe ratio of the magnitude of the inter-harmonic to the fundamental, the percentage of which is expressed, can be called the frequency fIHThe inter-harmonic content of (2).
And 3, taking the relative change transmission coefficient of electricity and light of the incandescent lamp as a reference, and obtaining the conversion coefficient of the LED lamp relative to the incandescent lamp by calculating the transmission coefficient ratio of the corresponding frequency of the incandescent lamp to the LED lamp.
The process of the step specifically comprises the following steps:
(1) A60W tungsten filament incandescent lamp of 230V/50Hz and 120V/60Hz is selected as an object according to a flicker measurement model establishment basis of IEC 61000-4-15 standard.
(2) Calculating the transmission coefficient G of the electric and light relative change of the incandescent lamp with different voltages and frequencies according to the formulas (7) and (8)lamp,ref(fIH)。
230V/50Hz 60W tungsten filament incandescent lamp:
120V/60Hz 60W tungsten filament incandescent lamp:
attention is paid to: the incandescent lamp is only affected by the inter-harmonic within 100Hz, so for the inter-harmonic higher than 100Hz, the transmission coefficients of the relative change of the electricity and the light of the incandescent lamp within 100Hz can be equivalently adopted in sequence according to the sequence from low frequency to high frequency.
(3) And (3) selecting an incandescent lamp matched with the rated voltage and frequency of the tested LED lamp as a reference according to the rated voltage and frequency of the tested LED lamp, and then calculating the relative change transmission coefficient ratio of electricity to light of the corresponding frequency of the reference incandescent lamp and the tested LED lamp to obtain the conversion coefficient of the LED lamp relative to the incandescent lamp, wherein the formula is (9).
And 4, calculating the inter-harmonic content corresponding to the incandescent lamp under the flicker limit value condition by using the transfer function of the visual perception weighting filter based on the incandescent lamp, and then multiplying the inter-harmonic content by the conversion coefficient of the corresponding frequency to calculate the flicker-limited LED lamp inter-harmonic tolerance level.
(1) According to the transfer functions of the 230V/50Hz and 120V/60Hz 60W tungsten filament incandescent lamp visibility weighting filters given by the IEC 61000-4-15 standard, the module values corresponding to the transfer functions at different frequencies are calculated according to the formula (10), and the visibility weighting coefficient G is obtainedw(fIH)。
In the formula: s j2 pi x fIH-hf1I, j denotes an imaginary number, k, lambda, omega1、ω2、ω3And ω4The parameters are shown in Table 1.
TABLE 1 Vision weighting Filter parameters
Similarly, for the inter-harmonics higher than 100Hz, the incandescent lamp visual sensation weighting coefficients within 100Hz can be equivalently adopted in sequence according to the sequence of the frequencies from low to high.
(2) P is calculated from the perceptibility weighting factor by the equation (11)stThe content of interharmonic corresponding to a 60W tungsten filament lamp with 230V, 50Hz, 120V and 60Hz when the lamp is 1.
(3) And (3) calculating the flicker-limited test LED lamp inter-harmonic content by multiplying the conversion coefficient of the tested LED lamp relative to the incandescent lamp by the corresponding inter-harmonic content of the incandescent lamp under the flicker limit condition, as shown in the formula (12).
When the supply voltage inter-harmonic content of the LED lamp meets the condition of the formula (13), the LED lamp can not generate visible light change for human eyes
Thus, the LED lamp has an inter-harmonic tolerance level of
The above process is described in detail with reference to specific examples, the values used in this example are only examples, and the user may make corresponding changes according to actual needs, in this example, the rated voltage of the tested LED lamp is 230V, the frequency is 50Hz, and the power is 16W, and the LED lamp is placed in the inter-harmonic-illuminance testing system as required, and the programmable power supply is controlled to generate the 230V and 50Hz fundamental voltage, on this basis, the frequency sweep interval of 1Hz, the superposition duration is 2s, and the inter-harmonic content is constant as 5% in the range of 1Hz to 200 Hz.
The data acquisition device is used for synchronously recording inter-harmonic voltage and illuminance variation data, and Fast Fourier Transform (FFT) is respectively carried out at analysis intervals of 50 cycles, for example, 45Hz inter-harmonic is taken as an example, the corresponding illuminance component is 5Hz, and the time-frequency domain result of the analysis is tested and shown in fig. 1. The fundamental voltage amplitude U is obtained1Frequency of fIHInter-harmonic amplitude U (f)IH) And a DC component L of illuminanceDCAnd a frequency of fM＝|fIH-hf1L (f) illuminance amplitude of |M) Calculating the transmission coefficient G of the relative change between electricity and light of the LED lamp corresponding to each inter-harmonic frequency according to the ratio of the relative change of the illuminance to the relative change of the inter-harmonic voltage, as shown in formula (6)LED(fIH) As shown in fig. 2.
According to rated voltage and frequency of the LED lamp, a 60W tungsten filament lamp with the voltage of 230V/50Hz is selected as a reference, and the relative change transfer coefficient G of electricity and light of the tungsten filament lamp is calculated according to the formula (7)lamp,ref(fIH) As shown in fig. 3. The electricity and light with the corresponding frequency of the reference incandescent lamp and the tested LED lampThe relative change transfer coefficient ratio (equation (9)) was calculated as the conversion coefficient of the LED lamp to the incandescent lamp, and the result is shown in fig. 4. Then, according to the vision sensitivity transfer function given by IEC, P is solvedstThe inter-harmonic content rate corresponding to a 60W incandescent lamp at 230V/50Hz at 1 is, as shown in fig. 5, multiplied by the conversion coefficient of the LED lamp with respect to the incandescent lamp to obtain the flicker-limited LED lamp inter-harmonic content rate as shown in fig. 5, and the content rate is the inter-harmonic tolerance level of the LED lamp.
The invention is described in detail above with reference to the figures and examples. It should be understood that in practice the description of all possible embodiments is not exhaustive and that the inventive concepts are described herein as far as possible by way of illustration. Without departing from the inventive concept of the present invention and without any creative work, a person skilled in the art should, in all of the embodiments, make optional combinations of technical features and experimental changes of specific parameters, or make a routine replacement of the disclosed technical means by using the prior art in the technical field to form specific embodiments, which belong to the content implicitly disclosed by the present invention.
Claims (3)
1. A method of estimating flicker-limited inter-lamp harmonic tolerance levels of an LED, comprising the steps of:
exciting the LED lamp to emit light by using an excitation voltage, and measuring the illuminance, wherein the excitation voltage is formed by a fundamental voltage and a frequency fIHIs mixed with the inter-harmonic voltage of frequency fIHInter-harmonic voltage excited light flicker frequency of
fM＝|fIH-h×f1| (1)
In the formula (f)1Is the fundamental voltage frequency, h being closest to fIHH 1,3,5, …, fIH≠h×f1；
Carrying out frequency domain analysis on the excitation voltage to obtain a fundamental voltage amplitude U1Frequency of fIHInter-harmonic amplitude U (f)IH) Analyzing the illuminance in frequency domain to obtain the DC component of the illuminanceLDCAnd a frequency of fMIlluminance amplitude L (f)M) Then the relative change transmission coefficient of electricity and light of the LED lamp
Obtaining the relative change transmission coefficient G of electricity and light of the incandescent lamplamp,ref(fIH) Wherein the rated voltage of the incandescent lamp is equal to the rated voltage of the LED lamp, the rated frequency of the incandescent lamp is equal to the rated frequency of the LED lamp, and the conversion coefficient of the LED lamp relative to the incandescent lamp is obtained
Obtaining a short-time flicker limit value PstWhen the frequency is 1, the interharmonic content of the incandescent lamp
In the formula, Gw(fIH) Weighting coefficients for the perceptibility of said incandescent lamp;
the inter-harmonic tolerance level of the LED lamp is
2. The method of estimating flicker-limited LED lamp-to-lamp harmonic tolerance level of claim 1, wherein the frequency domain analysis algorithm is a fast fourier transform algorithm.
3. The method of claim 1, wherein the fundamental voltage is an alternating current determined by a rated voltage and a rated frequency of the LED lamp.
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| CN104155542A (en) * | 2014-07-15 | 2014-11-19 | 中国船舶重工集团公司第七一九研究所 | Detection method suitable for flickering generated by high-frequency inter-harmonics |
| WO2016134382A1 (en) * | 2015-02-21 | 2016-08-25 | Kla-Tencor Corporation | Optimizing computational efficiency by multiple truncation of spatial harmonics |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104155542A (en) * | 2014-07-15 | 2014-11-19 | 中国船舶重工集团公司第七一九研究所 | Detection method suitable for flickering generated by high-frequency inter-harmonics |
| WO2016134382A1 (en) * | 2015-02-21 | 2016-08-25 | Kla-Tencor Corporation | Optimizing computational efficiency by multiple truncation of spatial harmonics |
Non-Patent Citations (2)
| Title |
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| SELCUK SAKAR: "Light intensity behavior of LED lamps within the thermal stabilization period", 《2018 18TH INTERNATIONAL CONFERENCE ON HARMONICS AND QUALITY OF POWER》, 11 June 2018 (2018-06-11) * |
| 汤志成;何益宏;: "LED灯的间谐波闪变分析", 计算机与信息技术, no. 04, 20 April 2010 (2010-04-20) * |
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