A method and system for adjusting the flicker index of an LED light source

Abstract

The present invention discloses a method and system for adjusting the flicker index of an LED light source, relating to the technical field of LED light sources. The method includes: obtaining the period, the number of LED devices, the driving signal parameters, and the light source parameters of the target LED light source; determining the maximum luminous flux according to the number of LED devices, the driving signal parameters, and the light source parameters; determining the flicker index according to the driving frequency, the maximum luminous flux, and the period; judging whether the flicker index is within a preset flicker index range; if not, adjusting the driving signal parameters, the junction temperature calculation parameters, and the first correlation coefficient until the flicker index is within the preset flicker index range. Compared with the existing methods of adjusting the flicker index by changing the circuit structure or changing the composition and preparation process of the phosphor material, the present invention can adjust the flicker index by adjusting the driving signal parameters, the junction temperature calculation parameters, and the first correlation coefficient, reducing the consumption of manpower, material resources, and financial resources and saving costs.

Description

Technical Field

[0001] The present invention relates to the technical field of LED light sources, and particularly to a method and system for adjusting the flicker index of an LED light source. Background Art

[0002] According to the IEEE (Institute of Electrical and Electronics Engineers) standard, the risks brought by stroboscopic are related to the modulation depth and the flicker frequency; the higher the frequency, the greater the allowable modulation depth. This standard gives corresponding suggestions for the potential health problems caused by stroboscopic. Currently, various types of lamps on the market have different degrees of stroboscopic effects, especially the modulation depth of LED lamps can reach 90%. Currently, domestic and foreign scholars have focused on how to reduce the modulation depth of the ripple current. For example, the method of injecting the third harmonic is applied to the Boost-PFC circuit in the critical conduction mode; the third harmonic injection method is further extended to the injection of the third plus fifth harmonics and applied to the Boost-PFC circuit in the discontinuous conduction mode to further reduce the modulation depth of the ripple current, thereby controlling the flicker index of the LED light source. A current-limiting resistor or the current-limiting impedance in a linear voltage regulator system is used. However, the current-limiting resistor will cause obvious losses, and a sufficiently large filter capacitor is required to reduce the modulation depth of the current ripple of the DC current, so as to achieve the purpose of controlling the flicker index of the LED light source. The current-limiting inductor is placed in the auxiliary circuit of the AC output area, and an improved driver is used to replace the current fluorescent ballast. The maximum energy storage per watt of this passive drive system is 0.011 J / W, which can effectively control the modulation depth of the ripple current, thereby achieving the purpose of controlling the flicker index of the LED light source. The methods adopted above all control the amplitude of the ripple current by optimizing the design of the switching power supply structure for driving the LED light source, so as to achieve the purpose of controlling the flicker index of the LED light source.

[0003] The phosphor material on the surface of the white LED light source can be regarded as an optical low-pass filter, which has a photorefractive effect and can effectively reduce the emission modulation depth of the LED light source. Based on YAG (yttrium aluminum garnet) phosphor, elements such as Ga (gallium), Ce (cerium), and Pr (praseodymium) are added. When the composition ratio is 1% Ce 3+ , 1% Pr:Y 2.98 Al2Ga3O 12 phosphor, under the effective excitation of blue light, the afterglow time reaches 60 minutes, achieving the purpose of controlling the flicker index of the LED light source. Using Ce 3+ :Gd3Al2Ga3O 12 (Ce 3+: The GdAGG) phosphor compensates for the stroboscopic effect of AC-LED. Under blue light excitation, the average afterglow time of this phosphor is 115 ms. On the other hand, Mg3Y2(Ge 1-x Six)3O 12 :Ce 3+ (x = 0 - 0.5) phosphors can also be effectively excited by blue LED chips, and the afterglow time of the phosphors is in the millisecond range, which can effectively reduce the stroboscopic depth of AC-LED and achieve the purpose of controlling the flicker index of the LED light source. The methods adopted above are all through optimizing the phosphor materials coated on the LED chip, so as to control the afterglow time and achieve the purpose of controlling the flicker index of the LED light source.

[0004] The above two methods respectively need to modify the switching power supply circuit structure for driving the LED light source and change the phosphor material composition and preparation process to achieve the purpose of controlling the ripple current and the flicker index. Whether changing the circuit structure or changing the phosphor material composition and preparation process requires a lot of manpower, material resources and financial resources. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for adjusting the flicker index of an LED light source to save costs.

[0006] To achieve the above purpose, the present invention provides the following solution:

[0007] A method for adjusting the flicker index of an LED light source, the method comprising:

[0008] Obtain the period, the number of LED devices, the drive signal parameters and the light source parameters of the target LED light source; the drive signal parameters include: drive frequency and drive electric power amplitude; the light source parameters include: junction temperature calculation parameters, preset reference temperature, first correlation coefficient and reference luminous efficiency; the junction temperature calculation parameters include: heat sink temperature, thermal resistance and thermal power consumption coefficient, the first correlation coefficient is the correlation coefficient between the luminous efficiency of the target LED light source and the junction temperature, and the reference luminous efficiency is the luminous efficiency of the target LED light source at the preset reference temperature;

[0009] Determine the maximum luminous flux of the target LED light source according to the number of LED devices, the drive signal parameters and the light source parameters;

[0010] Determine the flicker index of the target LED light source according to the drive frequency, the maximum luminous flux and the period;

[0011] Judge whether the flicker index is within a preset flicker index interval;

[0012] If not, adjust the drive signal parameters, the junction temperature calculation parameters, and the first correlation coefficient of the target LED light source until the flicker index is within the preset flicker index range.

[0013] Optionally, determining the maximum luminous flux of the target LED light source according to the number of LED devices, the drive signal parameters, and the light source parameters specifically includes:

[0014] Determine the luminous power of the target LED light source according to the drive signal parameters and the light source parameters;

[0015] Determine the maximum load electric power of the target LED light source according to the number of LED devices and the light source parameters;

[0016] Determine the maximum luminous flux of the target LED light source according to the number of LED devices, the luminous power, and the maximum load electric power.

[0017] Optionally, determining the luminous power of the target LED light source according to the drive signal parameters and the light source parameters specifically includes:

[0018] Determine the load electric power of the target LED light source according to the drive signal parameters;

[0019] Determine the junction temperature of the target LED light source according to the junction temperature calculation parameters and the load electric power;

[0020] Calculate the luminous power of the target LED light source according to the junction temperature, the preset reference temperature, the first correlation coefficient, and the reference luminous efficiency.

[0021] Optionally, determining the flicker index of the target LED light source according to the drive frequency, the maximum luminous flux, and the period specifically includes:

[0022] Determine the first time of the target LED light source according to the drive frequency and the maximum luminous flux;

[0023] Determine the average luminous flux of the target LED light source according to the maximum luminous flux and the period;

[0024] Determine the second time of the target LED light source according to the drive frequency and the average luminous flux;

[0025] Determine the flicker index of the target LED light source according to the maximum luminous flux, the first time, and the second time.

[0026] An adjustment system for the flicker index of an LED light source, comprising:

[0027] A parameter acquisition module for acquiring the period, the number of LED devices, the drive signal parameters, and the light source parameters of a target LED light source; the drive signal parameters include: a drive frequency and a drive electric power amplitude; the light source parameters include: a junction temperature calculation parameter, a preset reference temperature, a first correlation coefficient, and a reference luminous efficiency; the junction temperature calculation parameter includes: a heat sink temperature, a thermal resistance, and a thermal power consumption coefficient, the first correlation coefficient is the correlation coefficient between the luminous efficiency of the target LED light source and the junction temperature, and the reference luminous efficiency is the luminous efficiency of the target LED light source at the preset reference temperature;

[0028] A maximum luminous flux determination module for determining the maximum luminous flux of the target LED light source according to the number of LED devices, the drive signal parameters, and the light source parameters;

[0029] A flicker index determination module for determining the flicker index of the target LED light source according to the drive frequency, the maximum luminous flux, and the period;

[0030] A judgment module for judging whether the flicker index is within a preset flicker index range;

[0031] An adjustment module for, if the output of the judgment module is no, adjusting the drive signal parameters, the junction temperature calculation parameters, and the first correlation coefficient of the target LED light source until the flicker index is within the preset flicker index range.

[0032] Optionally, the maximum luminous flux determination module specifically includes:

[0033] A luminous power determination unit for determining the luminous power of the target LED light source according to the drive signal parameters and the light source parameters;

[0034] A maximum load electric power determination unit for determining the maximum load electric power of the target LED light source according to the number of LED devices and the light source parameters;

[0035] A maximum luminous flux determination unit for determining the maximum luminous flux of the target LED light source according to the number of LED devices, the luminous power, and the maximum load electric power.

[0036] Optionally, the luminous power determination unit specifically includes:

[0037] A load electric power determination subunit for determining the load electric power of the target LED light source according to the drive signal parameters;

[0038] A junction temperature determination subunit for determining the junction temperature of the target LED light source according to the junction temperature calculation parameters and the load electric power;

[0039] A luminous power determination subunit, configured to calculate the luminous power of the target LED light source according to the junction temperature, the preset reference temperature, the first correlation coefficient, and the reference luminous efficiency.

[0040] Optionally, the flicker index determination module specifically includes:

[0041] A first time determination unit, configured to determine the first time of the target LED light source according to the driving frequency and the maximum luminous flux;

[0042] An average luminous flux determination unit, configured to determine the average luminous flux of the target LED light source according to the maximum luminous flux and the period;

[0043] A second time determination unit, configured to determine the second time of the target LED light source according to the driving frequency and the average luminous flux;

[0044] A flicker index determination unit, configured to determine the flicker index of the target LED light source according to the maximum luminous flux, the first time, and the second time.

[0045] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0046] The present invention discloses a method and a system for adjusting the flicker index of an LED light source. The method includes: obtaining the period, the number of LED devices, the driving signal parameters, and the light source parameters of a target LED light source; the driving signal parameters include: the driving frequency and the driving electric power amplitude; the light source parameters include: the junction temperature calculation parameters, the preset reference temperature, the first correlation coefficient, and the reference luminous efficiency; determining the maximum luminous flux according to the number of LED devices, the driving signal parameters, and the light source parameters; determining the flicker index according to the driving frequency, the maximum luminous flux, and the period; determining whether the flicker index is within a preset flicker index range; if not, adjusting the driving signal parameters, the junction temperature calculation parameters, and the first correlation coefficient until the flicker index is within the preset flicker index range. Compared with the existing methods for adjusting the flicker index by changing the circuit structure or changing the composition and preparation process of the phosphor material, the present invention can adjust the flicker index by adjusting the driving signal parameters, the junction temperature calculation parameters, and the first correlation coefficient, reducing the consumption of manpower, material resources, and financial resources, and saving costs. Description of the Drawings

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 Flow chart of the adjustment method for the flicker index of the LED light source provided by the embodiment of the present invention;

[0049] Figure 2 Variation diagram of the luminous flux of the LED light source provided by the embodiment of the present invention under different parameters;

[0050] Figure 3 The load electric power P of the LED light source provided by the embodiment of the present invention d And the first correlation coefficient k e Relationship diagram;

[0051] Figure 4 The load electric power P of the LED light source provided by the embodiment of the present invention d And the thermal power consumption coefficient k h Relationship diagram;

[0052] Figure 5 Relationship diagram between the luminous flux and time of the LED light source provided by the embodiment of the present invention.

[0053] Figure 6 Relationship diagram between the flicker index of the LED light source provided by the embodiment of the present invention and the heat sink temperature T hs Relationship diagram;

[0054] Figure 7 Relationship diagram between the flicker index of the LED light source provided by the embodiment of the present invention and the driving electric power amplitude P d,max Relationship diagram;

[0055] Figure 8 Relationship diagram between the flicker index of the LED light source provided by the embodiment of the present invention and the driving frequency f;

[0056] Figure 9 Relationship diagram between the flicker index of the LED light source provided by the embodiment of the present invention and the thermal resistance R jc Relationship diagram;

[0057] Figure 10 Block diagram of the adjustment system for the flicker index of the LED light source provided by the embodiment of the present invention;

[0058] Figure 11 The maximum luminous flux Φ of the LED light source calculated by using the method provided by the present invention V,max And the driving electric power amplitude P d,max Relationship diagram;

[0059] Figure 12 The maximum luminous flux Φ of the LED light source tested by using an optical stroboscopic device V,max And the driving electric power amplitude P d,max Relationship diagram;

[0060] Figure 13 The average luminous flux Φ of the LED light source calculated by using the method provided by the present invention v,ave and the driving electric power amplitude P d,max relation diagram;

[0061] Figure 14 The average luminous flux Φ of the LED light source tested by using an optical stroboscopic device v,ave and the driving electric power amplitude P d,max relation diagram;

[0062] Figure 15 The stroboscopic index of the LED light source calculated by using the method provided by the present invention and the driving electric power amplitude P d,max relation diagram;

[0063] Figure 16 The stroboscopic index of the LED light source tested by using an optical stroboscopic device and the driving electric power amplitude P d,max relation diagram. Detailed implementation manners

[0064] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0065] The purpose of the present invention is to provide a method and system for adjusting the stroboscopic index of an LED light source, aiming to save costs and can be applied to the technical field of LED light sources.

[0066] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0067] Figure 1 It is a flow chart of the method for adjusting the stroboscopic index of the LED light source provided by the embodiment of the present invention. As Figure 1 shown, the method for adjusting the stroboscopic index of the LED light source in this embodiment includes:

[0068] Step 101: Obtain the period, the number of LED devices, the driving signal parameters, and the light source parameters of the target LED light source; the driving signal parameters include: driving frequency and driving electric power amplitude; the light source parameters include: junction temperature calculation parameters, preset reference temperature, first correlation coefficient, and reference luminous efficiency; the junction temperature calculation parameters include: heat sink temperature, thermal resistance, and thermal power consumption coefficient, the first correlation coefficient is the correlation coefficient between the luminous efficiency and the junction temperature of the target LED light source, and the reference luminous efficiency is the luminous efficiency of the target LED light source at the preset reference temperature.

[0069] Step 102: Determine the maximum luminous flux of the target LED light source according to the number of LED devices, the driving signal parameters, and the light source parameters.

[0070] Step 103: Determine the flicker index of the target LED light source according to the driving frequency, the maximum luminous flux, and the period.

[0071] Step 104: Determine whether the flicker index is within the preset flicker index range.

[0072] Step 105: If not, adjust the driving signal parameters, the junction temperature calculation parameters, and the first correlation coefficient of the target LED light source until the flicker index is within the preset flicker index range.

[0073] As an optional implementation manner, step 102 specifically includes:

[0074] Determine the luminous power of the target LED light source according to the driving signal parameters and the light source parameters.

[0075] Determine the maximum load electric power of the target LED light source according to the number of LED devices and the light source parameters.

[0076] Determine the maximum luminous flux of the target LED light source according to the number of LED devices, the luminous power, and the maximum load electric power.

[0077] As an optional implementation manner, determining the luminous power of the target LED light source according to the driving signal parameters and the light source parameters specifically includes:

[0078] Determine the load electric power of the target LED light source according to the driving signal parameters.

[0079] Determine the junction temperature of the target LED light source according to the junction temperature calculation parameters and the load electric power.

[0080] Calculate the luminous power of the target LED light source according to the junction temperature, the preset reference temperature, the first correlation coefficient, and the reference luminous efficiency.

[0081] As an optional implementation manner, step 103 specifically includes:

[0082] Determine the first time of the target LED light source according to the driving frequency and the maximum luminous flux.

[0083] Determine the average luminous flux of the target LED light source according to the maximum luminous flux and the period.

[0084] Determine the second time of the target LED light source according to the driving frequency and the average luminous flux.

[0085] Determine the flicker index of the target LED light source according to the maximum luminous flux, the first time, and the second time.

[0086] Specifically, the calculation steps of the flicker index are as follows:

[0087] The luminous flux Φ of the LED light source v Can be expressed as:

[0088] Φ v = NEP d (1)

[0089] Where N is the number of LED devices in the LED light source (the LED light source is composed of one or more LED devices), P d Is the load electric power of the LED light source, and E is the luminous efficiency of the LED light source.

[0090] Since the luminous efficiency E of the LED light source decreases as the device junction temperature increases, the luminous efficiency E of the LED light source can be expressed as:

[0091] E = E0[1 + k e (T j - T o )] (2)

[0092] Where k e Is the first correlation coefficient of the LED light source, that is, the correlation coefficient of the decrease in the luminous efficiency of the LED light source as the device junction temperature increases, T j Is the junction temperature of the LED light source, E0 is the luminous efficiency of the LED light source under the reference temperature T o Condition, and the two parameters E0 and T o Can be provided in the product specification of the LED light source and are known quantities.

[0093] Substitute formula (2) into formula (1), and the luminous flux Φ emitted by the LED light source v Can be expressed as:

[0094] Φ v = NEP d = NE0[1 + k e (T j - T o )]P d (3)

[0095] Among them, the junction temperature T of the LED light source j can be expressed as:

[0096] T j = T hs + R jc P heat = T hs + R jc P d k h (4)

[0097] Among them, T hs is the heat sink temperature of the LED light source, R jc is the thermal resistance of the LED light source, P heat is the thermal power consumption of the LED light source, k h is the thermal power consumption coefficient of the LED light source. R jc and P heat can be found in the product specification of the LED light source and are known quantities.

[0098] Substitute formula (4) into formula (3), then the general expression of the luminous flux Φ of the LED light source v is:

[0099] Φ v = NE0[1 + k e (T hs + R jc P d k h - T o )]P d == (1 + k e T hs - k e T0)NE0P d + NE0k e k h R jc P d 2 (5)

[0100] Since k e is negative and less than 1, formula (5) can be expressed as: Φ v = α1P d + α2P d 2 , where α1 and α2 are positive coefficients. As the load electric power P d increases, the luminous flux Φ v increases linearly. As the load electric power P d continues to increase, the second term in formula (5) continues to increase and becomes the dominant role, then the luminous flux Φ vIt shows a non - linear increase and finally reaches saturation. When the output luminous flux Φ of the LED light source v reaches the maximum value, as the load electric power P d increases, the luminous flux Φ v decreases. By analyzing Equation (5), it can be seen that as k h , R jc , T hs increase, the non - linear region of the output luminous flux Φ of the LED light source v becomes larger, as shown in Figure 2 . The luminous flux output by the LED light source follows a non - linear change law, with a maximum value. The value of this extreme point is Equation (5) Φ v is differentiated with respect to P d to obtain:

[0101]

[0102] Through experimental tests, it is found that the thermal power consumption coefficient k of the LED light source h and the first correlation coefficient k of the LED light source e both change with the load electric power P d , as shown in Figure 3 and 4 . Therefore, k h and k e can be expressed as:

[0103] k h =α h P d +β h (7)

[0104] k e =α e P d +β e (8)

[0105] where α h and β h are the correlation coefficients between k h and P d , and α e and β e are the correlation coefficients between k e and P d .

[0106] Substituting Equations (7) and (8) into Equation (6), then Equation (6) can be expressed as:

[0107]

[0108] When α e and α hnot equal to 0, and At present, the maximum luminous flux Φ V,max The corresponding maximum load electric power can be expressed as:

[0109]

[0110] Substitute formula (10) into formula (5), then the maximum luminous flux Φ V,max can be expressed as:

[0111]

[0112] For the sake of simplifying the engineering design, assume that the load electric power P d varies by k e and k h are constant values, then α e and α h are equal to 0, when At present, the maximum luminous flux Φ V,max The corresponding maximum load electric power can be expressed as:

[0113]

[0114] Substitute formula (12) into formula (5), then the maximum luminous flux Φ V,max can be expressed as:

[0115]

[0116] When calculating the luminous flux, two variables k h and k e are involved. If it is considered that these two variables remain constant as the load electric power changes P d then the maximum luminous flux Φ V,max shall be subject to formula (13). If it is considered that these two variables change as the load electric power changes and the change trend is taken into account, then the maximum luminous flux Φ V,max shall be subject to formula (11).

[0117] Equations (11) and (13) refer to the quantitative model of the maximum luminous flux in the general case, which is applicable to the description of the luminous flux when the LED light source is in the DC drive mode. The so-called flicker index refers to the change of the electrical power of the LED light source load over time. If the LED flicker index is 0 when the LED light source is in the DC drive mode, there is no need to discuss it. The LED stroboscopic effect generally appears in the ripple current generated during the LED drive process, which in turn causes fluctuations in the output luminous flux. Since the LED drive circuit processes the AC mains through rectification, filtering, voltage regulation, etc. and inputs it to the terminal LED light source, the generated ripple current is simplified to be a sine wave waveform in the present invention. Therefore, in the present invention, the electrical power of the sine wave function of the LED light source load is taken as an example of the parameter (drive signal) of the input light source for analysis.

[0118] When the drive signal of the LED light source is a sine wave, the electrical power of the load P d can be expressed as:

[0119]

[0120] where f is the drive frequency, T is the period of the LED light source, P d,max is the amplitude of the drive electrical power, and t is the drive time.

[0121] Substituting Equation (14) into Equation (5), the output luminous flux of the LED light source changing with time in the sine wave mode of the drive signal can be expressed as:

[0122] Φ v (t)=(1 + k e T hs -k e T0)NE0[P d,max Sin(f180t)] + NE0k e k h R jc [P d,max Sin(f180t)] 2 (15)

[0123] Combined with Figure 2 , when the electrical power of the LED light source load is the amplitude P d,max of the drive electrical power, in this case, the output luminous flux of the LED light source is not necessarily equal to the maximum luminous flux Φ V,max .

[0124] Through Equations (10) and (12), it is possible to obtain in two different cases (when the heat dissipation capacity of the radiator of the LED light source is good enough, that is, the thermal resistance of the radiator is small, indicating that in this case, the decrease in the luminous efficiency of the LED light source with the increase of the electrical power is relatively low. Therefore, when the amplitude P d,maxThe maximum luminous flux Φ output by the LED light source in this case V,max , such as Figure 2 shown by the solid curve. When the heat dissipation capacity of the radiator of the LED light source is insufficient, that is, the thermal resistance of the radiator is large, it indicates that in this case, the luminous efficiency of the LED light source decreases significantly as the electric power increases. At this time, the LED output luminous flux - electric power curve is parabolic. Therefore, when the driving electric power amplitude P d,max is in this case, the luminous flux output by the LED light source is not the maximum value, and the maximum luminous flux Φ V,max appears at the vertex of the parabolic curve, that is, the electric power is Figure 2 shown by the dashed curve, and how to select the electric power in this case must be obtained through the calculation of this theoretical model. To sum up, the variation laws of the luminous flux and the load electric power in the above two cases are determined by the characteristics of the LED light source and the heat dissipation system itself. Under this condition, the maximum luminous flux Φ V,max corresponds to the maximum load electric power

[0125] such as Figure 5 shown, and it is divided into two cases:

[0126] Case 1: The maximum load electric power V,max corresponding to the maximum luminous flux Φ is equal to the driving electric power amplitude P d,max .

[0127] The LED light source outputs the maximum luminous flux Φ v,ave under the conditions of Case 1, which can be expressed as Φ V,max1 :

[0128]

[0129] The LED light source outputs the maximum luminous flux Φ V,max1 corresponding to the time t max under the conditions of Case 1, which can be expressed as t max1 :

[0130]

[0131] Among them, t max1 is the first time under the conditions of Case 1, that is, the time corresponding to the LED light source outputting the maximum luminous flux under the conditions of Case 1 within a single cycle.

[0132] The average luminous flux Φ v,ave of the LED light source within a single cycle under the conditions of Case 1 can be expressed as Φ v,ave1 :

[0133]

[0134] The LED light source outputs an average luminous flux Φ under the conditions of Case 1 v,ave1 The corresponding time t ave Can be expressed as t ave1 :

[0135]

[0136] Wherein, t ave1 Is the second time under the conditions of Case 1, that is, the time corresponding to the average luminous flux output by the LED light source under the conditions of Case 1 within a single period.

[0137] The LED light source flicker index FI can be expressed as:

[0138]

[0139] Wherein, A1 is the area above the reference benchmark point of the average luminous flux output by the LED light source, and A2 is the area below the reference benchmark point of the average luminous flux output by the LED light source. Such as Figure 5 , A1 is the integral of the luminous flux with respect to time, ranging from the average luminous flux to the maximum luminous flux position and then multiplied by 2, and A1 + A2 is the integral of the luminous flux with respect to time, ranging from the minimum luminous flux to the maximum luminous flux position and then multiplied by 2.

[0140] According to the above analysis, A1 under the conditions of Case 1 can be expressed as A 11 :

[0141]

[0142] A1 + A2 under the conditions of Case 1 can be expressed as A 11 + A 21 :

[0143]

[0144] Wherein, t min1 Is the third time under the conditions of Case 1, that is, the time corresponding to the minimum luminous flux output by the LED light source under the conditions of Case 1 within a single period.

[0145]

[0146] Wherein, Φ v,min Is the minimum luminous flux output by the LED light source under the conditions of Case 1:

[0147]

[0148] Wherein, P d,min Is the minimum value of the driving electric power.

[0149] Substitute Equation (21) and Equation (22) into Equation (20). When the maximum luminous flux Φ V,max The corresponding maximum load electric power is equal to the driving electric power amplitude P d,max (when in Case 1), the LED light source flicker index can be expressed as:

[0150]

[0151] Case 2: The maximum luminous flux Φ V,max The corresponding maximum load electric power is less than the driving electric power amplitude P d,max .

[0152] The LED light source outputs the maximum luminous flux Φ under the conditions of Case 2 V,max which can be expressed as Φ V,max2 :

[0153]

[0154] The LED light source outputs the maximum luminous flux Φ under the conditions of Case 2 V,max2 The corresponding time t max can be expressed as t max2 :

[0155]

[0156] where t max2 is the first time under the conditions of Case 2, that is, the time corresponding to the LED light source outputting the maximum luminous flux under the conditions of Case 1 within a single cycle.

[0157] The average luminous flux Φ of the LED light source within a single cycle under the conditions of Case 2 v,ave can be expressed as Φ v,ave2 :

[0158]

[0159] The LED light source outputs the average luminous flux Φ under the conditions of Case 2 v,ave2 The corresponding time t ave can be expressed as t ave2 :

[0160]

[0161] where t ave2 is the second time under the conditions of Case 2, that is, the time corresponding to the LED light source outputting the average luminous flux under the conditions of Case 2 within a single cycle.

[0162] According to the above analysis, A1 under the conditions of Case 2 can be expressed as A12 :

[0163]

[0164] Under the conditions of Case 2, A1 + A2 can be expressed as A 12 + A 22 :

[0165]

[0166] where t min2 is the third time under the conditions of Case 2, that is, the time corresponding to the minimum luminous flux output by the LED light source within a single period under the conditions of Case 2.

[0167]

[0168] where Φ v,min2 is the minimum luminous flux output by the LED light source under the conditions of Case 2:

[0169]

[0170] where P d,min is the minimum value of the driving electric power.

[0171] Substitute Formula (30) and Formula (31) into Formula (20). When the maximum load electric power V,max corresponding to the maximum luminous flux Φ is less than the driving electric power amplitude P d,max (when in Case 2), the LED light source flicker index can be expressed as:

[0172]

[0173] The above process combines the LED light source flicker index FI, the thermal power consumption coefficient k h , the first correlation coefficient k e , the heat sink temperature T hs , the driving frequency f, the thermal resistance R jc , and the driving electric power amplitude P d,max into one, revealing the internal connection law of their mutual intersection. Through Formulas (25) and (34), the flicker index of the white light LED light source can be accurately predicted under different heat sink temperatures, thermal power consumption coefficients, driving amplitudes, etc.

[0174] The following variation law can be obtained through experiments:

[0175] As Figure 6 shown, the thermal resistance R jc of the LED light source is 12 °C / W, the driving frequency f is 100 HZ, and the driving electric power amplitude P d,maxis 2W, and the thermal power consumption coefficient k h is 0.61, and the first correlation coefficient k e is -0.00082. When the heat sink temperature T hs varies within the range of 30°C - 90°C, as the heat sink temperature T hs increases, the LED flicker index decreases.

[0176] As Figure 7 shown, the thermal resistance R of the LED light source jc is 12°C / W, the driving frequency f is 100HZ, and the heat sink temperature T hs is 30°C, and the thermal power consumption coefficient k h is 0.61, and the first correlation coefficient k e is -0.00082. When the driving electric power amplitude P d,max varies within the range of 0.5W - 2W, as the driving electric power amplitude P d,max increases, the LED flicker index decreases.

[0177] As Figure 8 shown, the thermal resistance R of the LED light source jc is 12°C / W, the driving electric power amplitude P d,max is 1W, the heat sink temperature T hs is 30°C, and the thermal power consumption coefficient k h is 0.61, and the first correlation coefficient k e is -0.00082. When the driving frequency f varies within the range of 100HZ - 1100HZ, as the driving frequency f increases, the LED flicker index decreases.

[0178] As Figure 9 shown, the driving frequency f of the LED light source is 100HZ, the driving electric power amplitude P d,max is 1W, the heat sink temperature T hs is 30°C, and the thermal power consumption coefficient k h is 0.61, and the first correlation coefficient k e is -0.00082. When the thermal resistance R jc varies within the range of 9°C / W - 17°C / W, as the thermal resistance R jc increases, the LED flicker index decreases.

[0179] By experimentally comparing the above prediction results, it is found that the proposed model of the LED light source flicker index can relatively accurately predict the change law of the LED light source flicker index under actual working conditions, with a maximum error of 10.2%, an average error of 6.4%, and a minimum error of 1.3%.

[0180] As Figures 11 - 16 shown, the driving frequency f of the LED light source is 100HZ, and the thermal resistance R of the LED light sourcejc is 12 °C / W, the heat sink temperature T hs is 30 °C, the thermal power consumption coefficient k h is 0.61, the first correlation coefficient k e is -0.00082. When the driving electric power amplitude P d,max varies within the range of 0.2 W - 1.6 W, with the increase of the heat sink temperature, the calculated and measured values of the maximum luminous flux and the average luminous flux within a single period of the LED light source output are found. It is found that the proposed model of the LED light source luminous flux can more accurately predict the variation law of the LED light source luminous flux under actual working conditions, with a maximum error of 9.8% and an average error of 5.6%. Compared with the measured value, the calculated value of the flicker index has high accuracy.

[0181] From the above analysis, by controlling the thermal power consumption coefficient k h of the LED light source, the first correlation coefficient k e the heat sink temperature T hs the driving electric power amplitude P d,max the driving frequency f and the thermal resistance R jc of the LED light source, the transient luminous flux output by the LED light source can be effectively changed, thereby causing a change in the flicker index of the LED light source.

[0182] By predicting the change range of the light source flicker index, the LED thermal power consumption coefficient k h required for the required control range, the first correlation coefficient k e the heat sink temperature T hs the driving electric power amplitude P d,max the driving frequency f and the thermal resistance R jc can be determined. In this way, different types of LED light sources and drivers can be selected through the light source specification provided by the LED device manufacturer and the switching power supply parameters provided by the switching power supply manufacturer, so as to meet the requirements for the target value of the flash index. For example, if it is required that the specific light source flicker index satisfies the range of 0.5 - 0.6, the LED light source characteristic parameters and the driver characteristic parameters can be calculated and selected through the content of the present invention.

[0183] Figure 10 is the block diagram of the adjustment system for the LED light source flicker index provided by the embodiment of the present invention. As Figure 10 shown, the adjustment system for the LED light source flicker index in this embodiment includes:

[0184] A parameter acquisition module 201 is configured to acquire the period, the number of LED devices, drive signal parameters, and light source parameters of a target LED light source; the drive signal parameters include: a drive frequency and a drive electric power amplitude; the light source parameters include: a junction temperature calculation parameter, a preset reference temperature, a first correlation coefficient, and a reference luminous efficiency; the junction temperature calculation parameter includes: a heat sink temperature, a thermal resistance, and a thermal power consumption coefficient, the first correlation coefficient is a correlation coefficient between the luminous efficiency and the junction temperature of the target LED light source, and the reference luminous efficiency is the luminous efficiency of the target LED light source at the preset reference temperature.

[0185] A maximum luminous flux determination module 202 is configured to determine the maximum luminous flux of the target LED light source according to the number of LED devices, the drive signal parameters, and the light source parameters.

[0186] A flicker index determination module 203 is configured to determine the flicker index of the target LED light source according to the drive frequency, the maximum luminous flux, and the period.

[0187] A judgment module 204 is configured to judge whether the flicker index is within a preset flicker index range.

[0188] An adjustment module 205 is configured to, if the output of the judgment module 204 is negative, adjust the drive signal parameters, the junction temperature calculation parameters, and the first correlation coefficient of the target LED light source until the flicker index is within the preset flicker index range.

[0189] As an optional implementation manner, the maximum luminous flux determination module 202 specifically includes:

[0190] A luminous power determination unit is configured to determine the luminous power of the target LED light source according to the drive signal parameters and the light source parameters.

[0191] A maximum load electric power determination unit is configured to determine the maximum load electric power of the target LED light source according to the number of LED devices and the light source parameters.

[0192] A maximum luminous flux determination unit is configured to determine the maximum luminous flux of the target LED light source according to the number of LED devices, the luminous power, and the maximum load electric power.

[0193] As an optional implementation manner, the luminous power determination unit specifically includes:

[0194] A load electric power determination subunit is configured to determine the load electric power of the target LED light source according to the drive signal parameters.

[0195] A junction temperature determination subunit is configured to determine the junction temperature of the target LED light source according to the junction temperature calculation parameters and the load electric power.

[0196] A luminous power determining subunit, configured to calculate the luminous power of a target LED light source according to the junction temperature, a preset reference temperature, a first correlation coefficient, and a reference luminous efficiency.

[0197] As an optional implementation manner, the flicker index determining module 203 specifically includes:

[0198] A first time determining unit, configured to determine a first time of the target LED light source according to the driving frequency and the maximum luminous flux.

[0199] An average luminous flux determining unit, configured to determine the average luminous flux of the target LED light source according to the maximum luminous flux and the period.

[0200] A second time determining unit, configured to determine a second time of the target LED light source according to the driving frequency and the average luminous flux.

[0201] A flicker index determining unit, configured to determine the flicker index of the target LED light source according to the maximum luminous flux, the first time, and the second time.

[0202] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0203] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the device of the present invention and its core idea. At the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for adjusting the flicker index of an LED light source, characterized in that, The method includes: Obtaining the period of the target LED light source, the number of LED devices, the driving signal parameters, and the light source parameters; the driving signal parameters include: the driving frequency and the driving electric power amplitude; the light source parameters include: the junction temperature calculation parameters, the preset reference temperature, the first correlation coefficient, and the reference luminous efficiency; the junction temperature calculation parameters include: the heat sink temperature, the thermal resistance, and the thermal power consumption coefficient, the first correlation coefficient is the correlation coefficient between the luminous efficiency of the target LED light source and the junction temperature, and the reference luminous efficiency is the luminous efficiency of the target LED light source at the preset reference temperature; Determining the maximum luminous flux of the target LED light source according to the number of LED devices, the driving signal parameters, and the light source parameters; Determining the flicker index of the target LED light source according to the driving frequency, the maximum luminous flux, and the period; Judging whether the flicker index is within a preset flicker index range; If not, adjusting the driving signal parameters, the junction temperature calculation parameters, and the first correlation coefficient of the target LED light source until the flicker index is within the preset flicker index range; The determining the maximum luminous flux of the target LED light source according to the number of LED devices, the driving signal parameters, and the light source parameters specifically includes: Determining the luminous power of the target LED light source according to the driving signal parameters and the light source parameters; Determining the maximum load electric power of the target LED light source according to the number of LED devices and the light source parameters; Determining the maximum luminous flux of the target LED light source according to the number of LED devices, the luminous power, and the maximum load electric power.

2. The method for adjusting the flicker index of the LED light source according to claim 1, wherein, The determining the luminous power of the target LED light source according to the driving signal parameters and the light source parameters specifically includes: Determining the load electric power of the target LED light source according to the driving signal parameters; Determining the junction temperature of the target LED light source according to the junction temperature calculation parameters and the load electric power; Calculating the luminous power of the target LED light source according to the junction temperature, the preset reference temperature, the first correlation coefficient, and the reference luminous efficiency.

3. The method for adjusting the flicker index of the LED light source according to claim 1, wherein, The determining the flicker index of the target LED light source according to the driving frequency, the maximum luminous flux, and the period specifically includes: Determining the first time of the target LED light source according to the driving frequency and the maximum luminous flux; Determining the average luminous flux of the target LED light source according to the maximum luminous flux and the period; Determining the second time of the target LED light source according to the driving frequency and the average luminous flux; Determining the flicker index of the target LED light source according to the maximum luminous flux, the first time, and the second time.

4. An adjustment system for the flicker index of an LED light source, characterized in that, Including: A parameter acquisition module for acquiring the period of the target LED light source, the number of LED devices, the driving signal parameters, and the light source parameters; The driving signal parameters include: driving frequency and driving electric power amplitude; the light source parameters include: junction temperature calculation parameters, preset reference temperature, first correlation coefficient, and reference luminous efficiency; the junction temperature calculation parameters include: heat sink temperature, thermal resistance, and thermal power consumption coefficient, the first correlation coefficient is the correlation coefficient between the luminous efficiency of the target LED light source and the junction temperature, and the reference luminous efficiency is the luminous efficiency of the target LED light source at the preset reference temperature; The maximum luminous flux determination module is configured to determine the maximum luminous flux of the target LED light source according to the number of LED devices, the driving signal parameters, and the light source parameters; The flicker index determination module is configured to determine the flicker index of the target LED light source according to the driving frequency, the maximum luminous flux, and the period; The judgment module is configured to judge whether the flicker index is within a preset flicker index range; The adjustment module is configured to, if the output of the judgment module is negative, adjust the driving signal parameters, the junction temperature calculation parameters, and the first correlation coefficient of the target LED light source until the flicker index is within the preset flicker index range; The maximum luminous flux determination module specifically includes: The luminous power determination unit is configured to determine the luminous power of the target LED light source according to the driving signal parameters and the light source parameters; The maximum load electric power determination unit is configured to determine the maximum load electric power of the target LED light source according to the number of LED devices and the light source parameters; The maximum luminous flux determination unit is configured to determine the maximum luminous flux of the target LED light source according to the number of LED devices, the luminous power, and the maximum load electric power.

5. The adjustment system for the LED light source flicker index according to claim 4, characterized in that, The luminous power determination unit specifically includes: The load electric power determination sub-unit is configured to determine the load electric power of the target LED light source according to the driving signal parameters; The junction temperature determination sub-unit is configured to determine the junction temperature of the target LED light source according to the junction temperature calculation parameters and the load electric power; The luminous power determination sub-unit is configured to calculate the luminous power of the target LED light source according to the junction temperature, the preset reference temperature, the first correlation coefficient, and the reference luminous efficiency.

6. The adjustment system for the LED light source flicker index according to claim 4, wherein The flicker index determination module specifically includes: The first time determination unit is configured to determine the first time of the target LED light source according to the driving frequency and the maximum luminous flux; The average luminous flux determination unit is configured to determine the average luminous flux of the target LED light source according to the maximum luminous flux and the period; The second time determination unit is configured to determine the second time of the target LED light source according to the driving frequency and the average luminous flux; The flicker index determination unit is configured to determine the flicker index of the target LED light source according to the maximum luminous flux, the first time, and the second time.

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