A method and system for establishing LED model characterized by driving current and temperature

Abstract

The present invention provides a method and system for establishing an LED model characterized by a driving current and a temperature, belonging to the technical field of visible light communication. The method starts from a rate equation of LED carrier motion, obtains an equivalent circuit model of the LED and analytical solutions of each part of the model with respect to the driving current and the temperature from the small signal form and the steady-state form of the rate equation respectively; and further proposes a model of carrier experience time so that the analytical solution of the model only includes the driving current and the temperature, and the model coefficients are few, and the coefficients to be determined can be solved with at least three actual measurement results; the impedance and frequency response predicted by the model have a high degree of conformity with the actual measurement results, and at the same time, the system can be guided to compensate for the nonlinearity of the LED based on the LED working state predicted by the model, such as designing a dynamic equalizer so that the equalizer poles can be matched with the LED of the current working conditions at any time, so as to achieve the best equilibrium state.

Description

Technical Field

[0001] The present invention belongs to the technical field of visible light communication, and in particular relates to a method and system for establishing an LED model characterized by driving current and temperature. Background Art

[0002] Visible light communication and lighting integration is the use of visible light for lighting and information transmission at the same time. In order to meet both lighting and communication requirements, gallium nitride power LEDs with high brightness and fast modulation capabilities have become the preferred light source for visible light lighting systems. However, LED is a nonlinear device, and its current state in the visible light system cannot be directly obtained from electrical quantities, so it is necessary to model the nonlinearity of LEDs.

[0003] The existing LED model is a circuit equivalent model of lumped parameters. However, the proposal of such models mostly relies on experience to qualitatively propose the distribution characteristics of lumped components through the trend of impedance curves, and lacks models with physical mechanism descriptions. In addition, since the actual needs and working environment are in a dynamic state, that is, the driving current and working temperature of the LED are in a dynamic state, the model needs to be characterized by the driving current in addition to the working temperature, so that it can always reflect the current working state of the LED, so as to more effectively guide the entire system to compensate for the nonlinearity of the LED under the current conditions. The existing lumped parameter model can only obtain the lumped parameter change function of the current through the data fitting method after obtaining the measured data through a large number of experiments. This method only obtains the current function that best meets the current data characteristics through the data fitting method from a large amount of data, which wastes a lot of energy on obtaining data. Not only does it lack the embodiment of physical laws, but it also lacks the characterization of temperature, and ultimately has a poor effect on guiding the compensation of LED communication performance. Summary of the invention

[0004] Based on this, an embodiment of the present invention provides a method and system for establishing an LED model characterized by driving current and temperature, aiming to solve the problem in the prior art that traditional LED model establishment wastes a lot of energy on obtaining data, not only lacks the embodiment of physical laws, but also lacks the characterization of temperature, resulting in poor compensation effect in guiding LED communication performance.

[0005] A first aspect of an embodiment of the present invention provides a method for establishing an LED model characterized by a driving current and a temperature, which is applied to a gallium nitride power LED. The method comprises:

[0006] Obtaining a change relationship of carriers per unit time in a quantum well region and a quantum well outer cladding region of an LED, wherein the change relationship is represented by a corresponding rate equation;

[0007] Rewriting the rate equation as the sum of a DC steady-state quantity and a small-signal dynamic quantity;

[0008] According to the rewritten results, the small signal rate equation is determined, and combined with the capacitance formula, the admittance matrix is ​​obtained;

[0009] The carrier's different process experience time is defined as the time constant in the lumped parameter. Combined with the properties of the admittance matrix, the LED intrinsic equivalent circuit model structure is obtained. Combined with the parasitic parameters, the LED equivalent circuit model is obtained.

[0010] According to the LED equivalent circuit model, determine the impedance formula and frequency response formula;

[0011] According to the definition of different process experience time of carriers, capacitance formula and properties of admittance matrix, the steady-state form of the rate equation is solved to obtain the steady-state solution of each lumped parameter;

[0012] The different process experience times of carriers are modeled from a semi-physical and semi-empirical perspective with respect to driving current and temperature to obtain modeling results;

[0013] The impedance formula and the frequency response formula are rewritten through the steady-state solution of each lumped parameter and the modeling results to obtain the objective function, and the required parameter values ​​are extracted from the measured data according to the objective function;

[0014] According to the parameter values, undetermined coefficients of the LED equivalent circuit model are solved, and at the same time, the parasitic parameters are updated to the measured average values;

[0015] The final LED equivalent circuit model is determined according to the undetermined coefficients and the updated parasitic parameters.

[0016] Furthermore, the rate equation of carriers in the quantum well region of the LED is:

[0017]

[0018] The rate equation of carriers in the outer cladding region of the quantum well of the LED is:

[0019]

[0020] in, Nc , Nd are the number of particles in the quantum well outer envelope region and the quantum well region, I is the current entering the envelope, q is the charge, Csc is the internal barrier capacitance of the LED, Vc , Vd are the voltages applied to the quantum well outer cladding region and the quantum well region, respectively. τr , τeThe recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region, t For time, Cc is the capacitance associated with carrier access.

[0021] Furthermore, the sum of the DC steady-state quantity and the small signal dynamic quantity is expressed as:

[0022]

[0023] in, represents the steady-state value of the current entering the outer layer of the quantum well, that is, the driving current, is the small signal value of the current entering the outer cladding region of the quantum well, is the angular frequency, is a natural number, subscript 0 indicates steady-state quantity, j Is an imaginary unit.

[0024] Furthermore, the small signal rate equation is expressed as:

[0025]

[0026]

[0027] Cc is the capacitance associated with carrier access.

[0028] Furthermore, the admittance matrix is ​​expressed as:

[0029]

[0030] Nc (ω) is the small signal value of the number of particles in the outer envelope of the quantum well, Nd (ω) is the small signal value of the number of particles in the quantum well region, is the small signal value of the current entering the outer cladding region of the quantum well, q is the charge, Csc is the internal barrier capacitance of the LED, Vc (ω) is the small signal value of the voltage applied to the outer cladding region of the quantum well, Vd (ω) is the small signal value of the voltage applied to the quantum well region, τr , τe The recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region. t For time, Cc is the capacitance related to carrier access, is the angular frequency, j Is an imaginary unit.

[0031] Furthermore, in the step of determining the impedance formula and the frequency response formula according to the LED equivalent circuit model, the impedance formula is expressed as:

[0032]

[0033] The frequency response formula is expressed as:

[0034]

[0035] in, R , Cb , Lb They are parasitic resistance, parasitic capacitance, and parasitic inductance, respectively. Cd is the capacitance related to carrier recombination in the quantum well, Rc is the resistance associated with carriers entering the quantum well, Rd is the resistance related to carrier recombination in the quantum well, is the angular frequency, j Is an imaginary unit.

[0036] Furthermore, in the modeling results, τr is modeled as:

[0037]

[0038] τe is modeled as:

[0039]

[0040] in, T is the absolute temperature, a 1 , b 1 , c 1 , a 2 , b 2 , c 2 are all undetermined coefficients, represents the steady-state value of the current entering the outer envelope region of the quantum well, exp represents the natural exponential function.

[0041] Furthermore, in the objective function, the impedance formula is rewritten as:

[0042]

[0043] The rewritten frequency response formula is:

[0044]

[0045] Among them, the parameter values ​​are extracted after actual measurement R , τr , τe , Cb , R , Lb , R for Rc and Rd The sum of , and only includes the drive current and absolute temperature, τr , τe The recombination time and escape time are respectively, R , Cb , Lb They are parasitic resistance, parasitic capacitance, and parasitic inductance, respectively. is the angular frequency, j Is an imaginary unit.

[0046] Furthermore, R It is expressed as:

[0047]

[0048] in, is the correction factor, n is the LED ideal factor, K is the Boltzmann constant, represents the steady-state value of the current entering the outer envelope region of the quantum well, q is the amount of charge.

[0049] A second aspect of an embodiment of the present invention provides a system for establishing an LED model characterized by a driving current and a temperature, for implementing the method for establishing an LED model characterized by a driving current and a temperature as described in the first aspect, the system comprising:

[0050] An acquisition module, used to acquire the change relationship of carriers in the quantum well region and the quantum well outer cladding region of the LED per unit time, wherein the change relationship is represented by a corresponding rate equation;

[0051] A first rewriting module, used for rewriting the rate equation into the sum of a DC steady-state quantity and a small signal dynamic quantity;

[0052] The first combining module is used to determine the small signal rate equation according to the rewriting result, and combine it with the capacitance formula to obtain the admittance matrix;

[0053] The second combining module is used to define the different process experience times of the carriers as the time constants in the lumped parameters, and combine the properties of the admittance matrix to obtain the LED intrinsic equivalent circuit model structure, and then combine the parasitic parameters to obtain the LED equivalent circuit model;

[0054] A first determination module is used to determine an impedance formula and a frequency response formula according to an LED equivalent circuit model;

[0055] The first analytical module is used to solve the steady-state form of the rate equation according to the definition of different process experience time of the carrier, the capacitance formula and the properties of the admittance matrix, and obtain the steady-state solution of each lumped parameter;

[0056] A modeling module is used to model the different process experience times of carriers with respect to driving current and temperature from a semi-physical and semi-empirical perspective to obtain modeling results;

[0057] The second rewriting module is used to rewrite the impedance formula and the frequency response formula through the steady-state solution of each lumped parameter and the modeling results to obtain the objective function, and extract the required parameter values ​​from the measured data according to the objective function;

[0058] A second analytical module is used to solve the undetermined coefficients of the LED equivalent circuit model according to the parameter values, and update the parasitic parameters to the measured average values;

[0059] The second determination module is used to determine the final LED equivalent circuit model according to the undetermined coefficients and the updated parasitic parameters.

[0060] A third aspect of the embodiments of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for establishing an LED model characterized by driving current and temperature provided in the first aspect.

[0061] A fourth aspect of an embodiment of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the program, the method for establishing an LED model characterized by driving current and temperature provided in the first aspect is implemented.

[0062] The beneficial effects of the LED model establishment method characterized by driving current and temperature provided by the present invention are as follows:

[0063] This method starts from the rate equation of LED carrier motion, and obtains the equivalent circuit model of LED and the analytical solutions of each part of the model regarding the driving current and temperature from the small signal form and steady-state form of the rate equation respectively; and further proposes a model about the carrier experience time so that the analytical solution of the model only contains the driving current and temperature, and the model coefficients are small, and at least only three actual measurement results are required to solve the unknown coefficients; the impedance and frequency response predicted by the model are highly consistent with the actual measurement results, and at the same time, the system can be guided to compensate for the nonlinearity of the LED based on the LED working state predicted by the model, such as designing a dynamic equalizer so that the equalizer poles can match the LED under the current working conditions at any time, so as to achieve the best equilibrium state. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 A flowchart of a method for establishing an LED model characterized by driving current and temperature provided in the first embodiment of the present invention;

[0065] Figure 2 This is a schematic diagram of the structure of a gallium nitride power LED;

[0066] Figure 3 is a schematic diagram of the equivalent circuit structure corresponding to the admittance matrix;

[0067] Figure 4 This is a schematic diagram of the complete equivalent circuit model structure of a GaN power LED;

[0068] Figure 5 The comparison chart of the measured impedance and the model prediction results of the LED at an operating temperature of 25°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0069] Figure 6 The comparison chart of the measured impedance results and the model prediction results of the LED at an operating temperature of 40°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0070] Figure 7 The comparison chart of the measured impedance results and the model prediction results of the LED at an operating temperature of 50°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0071] Figure 8 The comparison chart of the measured impedance results and the model prediction results of the LED at an operating temperature of 60°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0072] Fig. 9 The comparison chart of the measured frequency response and the model prediction results of the LED at an operating temperature of 25°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0073] Fig.10 The comparison chart of the measured frequency response and the model prediction results of the LED at an operating temperature of 40°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0074] Fig.11 The comparison chart between the measured frequency response results and the model prediction results of the LED at an operating temperature of 50°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0075] Fig.12 The comparison chart between the measured frequency response results and the model prediction results of the LED at an operating temperature of 60°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively;

[0076] Fig.13 This is a structural block diagram of a system for establishing an LED model characterized by driving current and temperature provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0077] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0078] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0079] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0080] Embodiment 1

[0081] According to an embodiment of the present invention, an embodiment of a method for establishing an LED model characterized by driving current and temperature is provided, which is applied to a gallium nitride power LED scenario. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than that here.

[0082] In the first embodiment of the present invention, a method for establishing an LED model characterized by driving current and temperature is provided, which can be used in electronic devices, such as computers. Figure 1 , Figure 1A flowchart of a method for establishing an LED model characterized by driving current and temperature provided in the first embodiment of the present invention is shown, which specifically includes steps S01 to S10.

[0083] Step S01, obtaining the variation relationship of carriers per unit time in the quantum well region and the quantum well outer cladding region of the LED, wherein the variation relationship is represented by a corresponding rate equation.

[0084] See also Figure 2 , which is a schematic diagram of the structure of a gallium nitride power LED, wherein the gallium nitride power LED includes an N-type gallium nitride layer 1, a quantum well layer 2, a P-type gallium nitride layer 3, a P-pole 4, an N-pole 5, and a wire 6. Specifically, the particle flow is the driving current plus the capacitance related to carrier access. Cc The rate equation of the additional particles and carriers in the quantum well region of the LED is:

[0085] (1.1)

[0086] The rate equation of carriers in the outer cladding region of the quantum well of the LED is:

[0087] (1.2)

[0088] in, Nc , Nd are the number of particles in the quantum well outer envelope region and the quantum well region, I is the current entering the envelope, q is the charge, Csc is the internal barrier capacitance of the LED, Vc , Vd are the voltages applied to the quantum well outer cladding region and the quantum well region, respectively. τr , τe The recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region. t is the time, and Cc is the capacitance related to carrier access.

[0089] Step S02, rewriting the rate equation as the sum of a DC steady-state quantity and a small signal dynamic quantity.

[0090] The sum of the DC steady-state quantity and the small signal dynamic quantity is expressed as:

[0091] (1.3)

[0092] in, represents the steady-state value of the current entering the outer layer of the quantum well, that is, the driving current, is the small signal value of the current entering the outer cladding region of the quantum well, is the angular frequency, is a natural number, subscript 0 indicates steady-state quantity, j Is an imaginary unit.

[0093] Step S03, determining the small signal rate equation according to the rewriting result, and combining it with the capacitance formula to obtain the admittance matrix.

[0094] Specifically, the small signal rate equation is expressed as:

[0095] (1.4)

[0096] (1.5)

[0097] From the capacitance formula:

[0098] (1.6)

[0099] (1.7)

[0100] Cd is the capacitance related to carrier recombination in the quantum well. Substituting equation (1.6) and equation (1.7) into equation (1.4) and equation (1.5), we get:

[0101] (1.11)

[0102] (1.12)

[0103] After simplification, the admittance matrix of the LED intrinsic equivalent model is obtained:

[0104] (1.13)

[0105] Nc (ω) is the small signal value of the number of particles in the outer envelope of the quantum well, Nd (ω) is the small signal value of the number of particles in the quantum well region, is the small signal value of the current entering the outer cladding region of the quantum well, q is the charge, Csc is the internal barrier capacitance of the LED, Vc (ω) is the small signal value of the voltage applied to the outer cladding region of the quantum well, Vd (ω) is the small signal value of the voltage applied to the quantum well region, τr , τe The recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region. t For time, Cc is the capacitance related to carrier access, is the angular frequency, j Is an imaginary unit.

[0106] Step S04, defining the different process experience times of the carriers as the time constants in the lumped parameters, combining the properties of the admittance matrix to obtain the LED intrinsic equivalent circuit model structure, and then combining the parasitic parameters to obtain the LED equivalent circuit model.

[0107] Specifically, the carrier's different process experience time τ is defined as the lumped parameter time constant:

[0108] (1.14)

[0109] (1.15)

[0110] τc is the time required for the carriers to enter the quantum well from the cladding, Rc is the resistance associated with carriers entering the quantum well, Rd is the resistance related to carrier recombination in the quantum well; at the same time, the admittance matrix must satisfy the equality of the non-main diagonal elements, that is:

[0111] (1.16)

[0112] Then formula (1.13) is further transformed into:

[0113] (1.17)

[0114] The equivalent circuit structure corresponding to the admittance matrix shown in equation (1.17) is as follows Figure 3 shown.

[0115] Step S05: determining an impedance formula and a frequency response formula according to an LED equivalent circuit model.

[0116] After taking into account the parasitic parameters caused by metal wires, packaging, etc., the complete equivalent circuit model of GaN power LED is obtained, as shown in Figure 4 As shown, R , Cb , Lb They are parasitic resistance, parasitic capacitance, and parasitic inductance, respectively. Cd is the capacitance related to carrier recombination in the quantum well, Rc is the resistance associated with carriers entering the quantum well, Rd is the resistance related to carrier recombination in the quantum well. Csc , Cc The magnitude of the composite capacitance is much smaller than Cdand parasitic capacitance Cb , so it can be ignored.

[0117] In this embodiment, the impedance formula is expressed as:

[0118] (1.18)

[0119] The frequency response formula is expressed as:

[0120] (1.19)

[0121] Step S06, solving the steady-state form of the rate equation according to the definitions of different process experience times of the carriers, the capacitance formula and the properties of the admittance matrix, and obtaining the steady-state solutions of the lumped parameters.

[0122] It should be noted that the steady-state forms of the rate equations (1.1) and (1.2) are:

[0123] (1.20)

[0124] (1.21)

[0125] That is, it represents the driving current, and the solution is:

[0126] (1.22)

[0127] Nc and Vc The relationship is:

[0128] (1.23)

[0129] n is the LED ideal factor, K is the Boltzmann constant, T is the absolute temperature, exp Represents the natural exponential function. Taylor approximation is used in the formula, and from formula (1.23) we get:

[0130] (1.24)

[0131] Combining equation (1.24) with equation (1.6) yields:

[0132] (1.25)

[0133] Combining equations (1.14), (1.15), (1.16), (1.22) and (1.25), we get:

[0134] (1.26)

[0135] (1.27)

[0136] (1.28)

[0137] Step S07 , modeling different process experience times of carriers with respect to driving current and temperature from a semi-physical and semi-empirical perspective to obtain a modeling result.

[0138] for τr , the square of its reciprocal is proportional to the drive current, and the exponential function of the reciprocal of temperature is added as a correction, so τr is modeled as:

[0139] (1.29)

[0140] a1 , b1 , c1 is the unknown coefficient, for τe , its temperature model is the thermal ion emission model, and the power function of the driving current is added as a correction, so τe is modeled as:

[0141] (1.30)

[0142] a2 , b2 , c2 is the unknown coefficient. From formula (1.23) and formula (1.25), we can know that Rc and Rd The sum is R , R It only includes the drive current and temperature. However, the ideal factor is not a constant, so a correction term is added, namely:

[0143] (1.31)

[0144] is the correction factor.

[0145] Step S08, rewriting the impedance formula and the frequency response formula through the steady-state solution of each lumped parameter and the modeling results to obtain the objective function, and extracting the required parameter values ​​from the measured data according to the objective function.

[0146] The rewritten impedance formula is:

[0147] (1.32)

[0148] The rewritten frequency response formula is:

[0149] (1.33)

[0150] Among them, the parameter values ​​are extracted after actual measurement R , τr , τe , Cb , R , Lb It can be understood that by measuring the impedance and frequency response data under at least three arbitrary conditions, the equations (1.32) and (1.33) can be used as the objective function to extract the impedance under these experimental conditions. R , τr , τ e , Cb , R , Lb The value of .

[0151] Step S09: solving the undetermined coefficients of the LED equivalent circuit model according to the parameter values, and updating the parasitic parameters to the measured average values.

[0152] because τe and τr Each contains three coefficients, so it is extracted from at least three sets of measured impedance and frequency response data. τr and τe The value of can be solved τr and τe The coefficient of the LED can also be extracted.

[0153] With the rewritten impedance and frequency response formula as the objective function, the coefficients to be determined in the model can be solved after the required parameter values ​​are extracted from the measured data. In addition, the parasitic parameters in the LED are not strongly dependent on the drive current or temperature, so the average value of the three sets of measured data can be taken.

[0154] Step S10, determining a final LED equivalent circuit model according to the undetermined coefficients and the updated parasitic parameters.

[0155] In this way, the function model of each part of the equivalent circuit model with respect to the driving current and temperature can be obtained, that is, the function model of the impedance and frequency response with respect to the driving current and temperature can be obtained. The state change of the LED can be predicted by this model, providing a basis for the system to compensate for the nonlinearity of the LED. For example, if the LED working pole is predicted by this model, the dynamic equalizer can be further designed based on the pole to ensure that the LED is in the best balanced state.

[0156] In summary, the method for establishing an LED model characterized by driving current and temperature in the above-mentioned embodiment of the present invention starts from the rate equation of the movement of LED carriers, and obtains the equivalent circuit model of the LED and the analytical solutions of each part of the model regarding the driving current and temperature from the small signal form and the steady-state form of the rate equation respectively; and further proposes a model regarding the carrier experience time so that the analytical solution of the model only includes the driving current and temperature, and the model coefficients are small, and at least only three actual measurement results are required to solve the unknown coefficients; the impedance and frequency response predicted by the model are highly consistent with the actual measurement results, and at the same time, the system can be guided to compensate for the nonlinearity of the LED based on the LED working state predicted by the model, such as designing a dynamic equalizer so that the equalizer poles can match the LED under the current working conditions at any time, so as to achieve the best equilibrium state.

[0157] Embodiment 2

[0158] In order to verify the LED model establishment method characterized by driving current and temperature in the first embodiment of the present invention, the impedance and frequency response data of the xpe2 red LED produced by Cree Company were extracted under the three conditions of driving current and temperature of 10mA, 25℃, 50mA, 25℃, 50mA, 60℃, and the impedance and frequency response data of the xpe2 red LED produced by Cree Company were extracted under the three conditions of driving current and temperature of 1 ... R , τr , τe , Cb , R , Lb The values ​​are shown in Table 1:

[0159] Table 1

[0160]

[0161] Will R , τr , τe Substituting the extracted value into equation (1.26), equation (1.27), and equation (1.28) in Example 1 yields:

[0162] (1.34)

[0163] (1.35)

[0164] (1.36)

[0165] Cb , R , Lb Take the average values ​​of 5.12E-10, 0.67, and 1.32E-9. From this, we can get the model of LED impedance and frequency response only related to drive current and temperature. Z(I,T) , H(I,T) , and can also be subdivided to obtain models of each part only related to drive current and temperature Rd(I,T) , Cd(I,T) , Rc(I,T) . See Figures 5 to 12 , Figure 5 The comparison chart of the measured impedance and the model prediction results of the LED at an operating temperature of 25°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively; Figure 6 The comparison chart of the measured impedance results and the model prediction results of the LED at an operating temperature of 40°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively; Figure 7 The comparison chart of the measured impedance results and the model prediction results of the LED at an operating temperature of 50°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively; Figure 8 The comparison chart of the measured impedance results and the model prediction results of the LED at an operating temperature of 60°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively; Fig. 9 The comparison chart of the measured frequency response and the model prediction results of the LED under the working temperature of 25℃ and the working current of 10mA, 20mA, 30mA, 40mA and 50mA respectively. The frequency response is the frequency response, the horizontal axis of the frequency response curve is the frequency, and the vertical axis is the response amplitude. Fig.10 The comparison chart of the measured frequency response and the model prediction results of the LED at an operating temperature of 40°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively; Fig.11 The comparison chart between the measured frequency response results and the model prediction results of the LED at an operating temperature of 50°C and operating currents of 10mA, 20mA, 30mA, 40mA, and 50mA respectively; Fig.12 This is a comparison chart of the measured frequency response results and the model prediction results when the LED is at an operating temperature of 60°C and an operating current of 10mA, 20mA, 30mA, 40mA, and 50mA respectively. It can be found that the measured results of impedance and frequency response are highly consistent with the model prediction results.

[0166] Embodiment 3

[0167] See also Fig.13 , Fig.13This is a structural block diagram of a system for establishing an LED model characterized by a driving current and a temperature, provided in the third embodiment of the present invention. The system 200 for establishing an LED model characterized by a driving current and a temperature is used to implement the above-mentioned embodiments and preferred implementations, and the descriptions that have been made will not be repeated. As used below, the term "module" may be a combination of software and / or hardware that implements a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, the implementation in hardware, or a combination of software and hardware, is also possible and conceivable.

[0168] Specifically, the LED model establishment system 200 characterized by driving current and temperature includes: an acquisition module 201, a first rewriting module 202, a first combining module 203, a second combining module 204, a first determining module 205, a first analyzing module 206, a modeling module 207, a second rewriting module 208, a second analyzing module 209 and a second determining module 210, wherein:

[0169] The acquisition module 201 is used to obtain the change relationship of the carrier in the quantum well region and the quantum well outer cladding region of the LED per unit time. The change relationship is represented by a corresponding rate equation. The rate equation of the carrier in the quantum well region of the LED is:

[0170]

[0171] The rate equation of carriers in the outer cladding region of the quantum well of the LED is:

[0172]

[0173] in, Nc , Nd are the number of particles in the cladding region and the quantum well region, I is the current entering the envelope, q is the charge, Csc is the internal barrier capacitance of the LED, Vc , Vd are the voltages applied to the cladding and quantum well regions, respectively, τr , τe The recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region. t For time;

[0174] The first rewriting module 202 is used to rewrite the rate equation into the sum of a DC steady-state quantity and a small-signal dynamic quantity. The sum of the DC steady-state quantity and the small-signal dynamic quantity is expressed as:

[0175]

[0176] in, represents the steady-state value of the current entering the cladding region, i.e., the driving current, is the small signal value of the current entering the cladding region, is the angular frequency, is a natural number, and the subscript 0 indicates a steady-state quantity;

[0177] The first combining module 203 is used to determine the small signal rate equation according to the rewriting result, and combine it with the capacitance formula to obtain the admittance matrix. The small signal rate equation is expressed as:

[0178]

[0179]

[0180] Cc is the capacitance related to carrier access, and the admittance matrix is ​​expressed as:

[0181] ;

[0182] The second combining module 204 is used to define the different process experience times of the carriers as the time constants in the lumped parameters, combine the properties of the admittance matrix to obtain the LED intrinsic equivalent circuit model structure, and then combine the parasitic parameters to obtain the LED equivalent circuit model;

[0183] The first determination module 205 is used to determine the impedance formula and the frequency response formula according to the LED equivalent circuit model. The impedance formula is expressed as:

[0184]

[0185] The frequency response formula is expressed as:

[0186]

[0187] in, R , Cb , Lb They are parasitic resistance, parasitic capacitance, and parasitic inductance, respectively. Cd is the capacitance related to carrier recombination in the quantum well, Rc is the resistance associated with carriers entering the quantum well, Rd is the resistance related to carrier recombination in the quantum well;

[0188] A first analytical module 206 is used to solve the steady-state form of the rate equation according to the definition of different process experience times of the carriers, the capacitance formula and the properties of the admittance matrix, and obtain the steady-state solutions of the lumped parameters;

[0189] The modeling module 207 is used to model the different process experience times of the carriers with respect to the driving current and temperature from a semi-physical and semi-empirical perspective to obtain a modeling result. τr is modeled as:

[0190]

[0191] τe is modeled as:

[0192]

[0193] in, T is the absolute temperature, a 1 , b 1 , c 1 , a 2 , b 2 , c 2 All are undetermined coefficients;

[0194] The second rewriting module 208 is used to rewrite the impedance formula and the frequency response formula through the steady-state solution of each lumped parameter and the modeling result to obtain the objective function. According to the objective function, the required parameter values ​​are extracted from the measured data. In the objective function, the rewritten impedance formula is:

[0195]

[0196] The rewritten frequency response formula is:

[0197]

[0198] Among them, the parameter values ​​are extracted after actual measurement R , τr , τe , Cb , R , Lb , R for Rc and Rd The sum of , and only includes the drive current and absolute temperature, R It is expressed as:

[0199]

[0200] in, n 0 is the correction factor, n is the LED ideal factor, K is the Boltzmann constant;

[0201] A second analytical module 209 is used to solve the undetermined coefficients of the LED equivalent circuit model according to the parameter values, and update the parasitic parameters to the measured average values;

[0202] The second determination module 210 is used to determine the final LED equivalent circuit model according to the undetermined coefficients and the updated parasitic parameters.

[0203] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0204] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. A method for establishing an LED model characterized by driving current and temperature, characterized in that: Applied to gallium nitride power LEDs, the method comprises: Obtaining a change relationship of carriers per unit time in a quantum well region and a quantum well outer cladding region of an LED, wherein the change relationship is represented by a corresponding rate equation; Rewriting the rate equation as the sum of a DC steady-state quantity and a small-signal dynamic quantity; According to the rewritten results, the small signal rate equation is determined, and combined with the capacitance formula, the admittance matrix is ​​obtained; The carrier's different process experience time is defined as the time constant in the lumped parameter. Combined with the properties of the admittance matrix, the LED intrinsic equivalent circuit model structure is obtained. Combined with the parasitic parameters, the LED equivalent circuit model is obtained. According to the LED equivalent circuit model, determine the impedance formula and frequency response formula; According to the definition of different process experience time of carriers, capacitance formula and properties of admittance matrix, the steady-state form of the rate equation is solved to obtain the steady-state solution of each lumped parameter; The different process experience times of the carriers are modeled from a semi-physical and semi-empirical perspective with respect to the driving current and temperature, and the modeling results are obtained. Among the modeling results, τr is modeled as: τe is modeled as: T is the absolute temperature, a 1. b 1. c 1. a 2. b 2. c 2 are all undetermined coefficients, I 0 represents the steady-state value of the current entering the outer cladding region of the quantum well, exp represents the natural exponential function, τr , τe Recombination time and escape time, respectively; The impedance formula and the frequency response formula are rewritten through the steady-state solution of each lumped parameter and the modeling results to obtain the objective function, and the required parameter values ​​are extracted from the measured data according to the objective function; According to the parameter values, undetermined coefficients of the LED equivalent circuit model are solved, and at the same time, the parasitic parameters are updated to the measured average values; The final LED equivalent circuit model is determined according to the undetermined coefficients and the updated parasitic parameters.

2. The method for establishing an LED model characterized by driving current and temperature according to claim 1, characterized in that: The rate equation of carriers in the quantum well region of the LED is: The rate equation of carriers in the outer cladding region of the quantum well of the LED is: in, Nc , Nd are the number of particles in the quantum well outer envelope region and the quantum well region, I is the current entering the envelope, q is the charge, Csc is the internal barrier capacitance of the LED, Vc , Vd are the voltages applied to the quantum well outer cladding region and the quantum well region, respectively. τr , τe The recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region, t For time, Cc is the capacitance associated with carrier access.

3. The method for establishing an LED model characterized by driving current and temperature according to claim 2, characterized in that: The sum of the DC steady-state quantity and the small signal dynamic quantity is expressed as: in, represents the steady-state value of the current entering the outer layer of the quantum well, that is, the driving current, is the small signal value of the current entering the outer cladding region of the quantum well, is the angular frequency, is a natural number, subscript 0 indicates steady-state quantity, j Is an imaginary unit.

4. The method for establishing an LED model characterized by driving current and temperature according to claim 3, characterized in that: The small signal rate equation is expressed as: Nc (ω) is the small signal value of the number of particles in the outer envelope region of the quantum well, Nd (ω) is the small signal value of the number of particles in the quantum well region, is the small signal value of the current entering the outer cladding region of the quantum well, q is the charge, Csc is the internal barrier capacitance of the LED, Vc (ω) is the small signal value of the voltage applied to the outer cladding region of the quantum well, Vd (ω) is the small signal value of the voltage applied to the quantum well region, τr , τe The recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region, t For time, Cc is the capacitance related to carrier access, is the angular frequency, j Is an imaginary unit.

5. The method for establishing an LED model characterized by driving current and temperature according to claim 4, characterized in that: The admittance matrix is ​​expressed as: is the small signal value of the current entering the outer cladding region of the quantum well, Csc is the internal barrier capacitance of the LED, Vc (ω) is the small signal value of the voltage applied to the outer cladding region of the quantum well, Vd (ω) is the small signal value of the voltage applied to the quantum well region, τ r , τe The recombination time and escape time are respectively, τc is the time required for carriers to enter the quantum well region from the quantum well outer cladding region, t For time, Cc is the capacitance related to carrier access, Cd is the capacitance related to carrier recombination in the quantum well, is the angular frequency, j Is an imaginary unit.

6. The method for establishing an LED model characterized by driving current and temperature according to claim 5, characterized in that: In the step of determining the impedance formula and the frequency response formula according to the LED equivalent circuit model, the impedance formula is expressed as: The frequency response formula is expressed as: in, R , Cb , Lb They are parasitic resistance, parasitic capacitance, and parasitic inductance, respectively. Cd is the capacitance related to carrier recombination in the quantum well, Rc is the resistance associated with carriers entering the quantum well, Rd is the resistance related to carrier recombination in the quantum well, is the angular frequency, j Is an imaginary unit.

7. The method for establishing an LED model characterized by driving current and temperature according to claim 6, characterized in that: In the objective function, the rewritten impedance formula is: The rewritten frequency response formula is: Among them, the parameter values ​​are extracted after actual measurement R , τr , τe , Cb , R , Lb , R for Rc and Rd The sum of , and only includes the drive current and absolute temperature, τr , τe The recombination time and escape time are respectively, R , Cb , Lb They are parasitic resistance, parasitic capacitance, and parasitic inductance, respectively. is the angular frequency, j Is an imaginary unit.

8. The method for establishing an LED model characterized by driving current and temperature according to claim 7, characterized in that: R It is expressed as: in, n 0 is the correction factor, n is the LED ideal factor, K is the Boltzmann constant, I 0 represents the steady-state value of the current entering the outer cladding region of the quantum well, q is the amount of charge.

9. A system for establishing an LED model characterized by driving current and temperature, characterized in that: The system is used to implement the method for establishing an LED model characterized by driving current and temperature as described in any one of claims 1 to 8, the system comprising: An acquisition module, used to acquire the change relationship of carriers in the quantum well region and the quantum well outer cladding region of the LED per unit time, wherein the change relationship is represented by a corresponding rate equation; A first rewriting module, used for rewriting the rate equation into the sum of a DC steady-state quantity and a small signal dynamic quantity; The first combining module is used to determine the small signal rate equation according to the rewriting result, and combine it with the capacitance formula to obtain the admittance matrix; The second combining module is used to define the different process experience times of the carriers as the time constants in the lumped parameters, and combine the properties of the admittance matrix to obtain the LED intrinsic equivalent circuit model structure, and then combine the parasitic parameters to obtain the LED equivalent circuit model; A first determination module is used to determine an impedance formula and a frequency response formula according to an LED equivalent circuit model; The first analytical module is used to solve the steady-state form of the rate equation according to the definition of different process experience time of the carrier, the capacitance formula and the properties of the admittance matrix, and obtain the steady-state solution of each lumped parameter; The modeling module is used to model the different process experience times of the carriers with respect to the driving current and temperature from a semi-physical and semi-empirical perspective to obtain the modeling results, wherein, in the modeling results, τr is modeled as: τe is modeled as: T is the absolute temperature, a 1. b 1. c 1. a 2. b 2. c 2 are all undetermined coefficients, I 0 represents the steady-state value of the current entering the outer cladding region of the quantum well, exp represents the natural exponential function, τr , τe Recombination time and escape time, respectively; The second rewriting module is used to rewrite the impedance formula and the frequency response formula through the steady-state solution of each lumped parameter and the modeling results to obtain the objective function, and extract the required parameter values ​​from the measured data according to the objective function; A second analytical module is used to solve the undetermined coefficients of the LED equivalent circuit model according to the parameter values, and update the parasitic parameters to the measured average values; The second determination module is used to determine the final LED equivalent circuit model according to the undetermined coefficients and the updated parasitic parameters.

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