A flyback transformer winding loss evaluation method, device, equipment and storage medium

Abstract

The application discloses a flyback transformer winding loss evaluation method, device, equipment and storage medium, and the method comprises the following steps: acquiring electrical data in a preset switching period, and actual primary side current waveform and actual secondary side current waveform of a to-be-tested flyback transformer under the electrical data, and constructing a current calculation model to obtain a primary side current change function and a secondary side current change function; then, the primary side current change function and the secondary side current change function are subjected to Fourier decomposition to obtain a primary side DC component, a primary side harmonic component, a secondary side DC component and a secondary side harmonic component; then, selected primary side harmonic components, selected primary side harmonic frequencies, selected secondary side harmonic components and selected secondary side harmonic frequencies are determined; subsequently, the primary side AC resistance, the primary side DC resistance, the secondary side AC resistance and the secondary side DC resistance of the flyback transformer are acquired; finally, the winding loss value of the to-be-tested flyback transformer is calculated. Through implementation of the application, the winding loss of the flyback transformer can be quantitatively calculated.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer loss assessment, and in particular to a method, device, equipment and storage medium for assessing the winding loss of a flyback transformer. Background Art

[0002] The power transmitted to the grid by a photovoltaic inverter is always less than the DC power generated by the solar cells. This is because losses occur during inverter operation, which are composed of active and passive device losses. Active devices include the driver circuit and semiconductor devices such as MOSFETs and diodes, while passive devices include transformers, filter inductors, and capacitors. These devices also consume energy during energy transmission due to various parameters. Flyback transformer winding losses account for a significant proportion of the overall losses in photovoltaic inverters. Improving photovoltaic inverter efficiency requires a thorough understanding of the transformer winding's operating conditions and a detailed analysis of the causes of flyback transformer winding losses.

[0003] However, in the prior art, it is impossible to quantitatively calculate the flyback transformer winding loss. Summary of the Invention

[0004] The present invention provides a flyback transformer winding loss evaluation method, device, equipment and storage medium, which can quantitatively calculate the flyback transformer winding loss.

[0005] An embodiment of the present invention provides a method for evaluating a flyback transformer winding loss, comprising:

[0006] Acquire electrical data within a preset switching cycle, as well as the actual primary current waveform and the actual secondary current waveform of the flyback transformer under test under the above electrical data, and construct a current calculation model based on the above electrical data; wherein the above electrical data includes: switching duty cycle, secondary voltage, secondary current average value, and secondary current change;

[0007] According to the above current calculation model, a primary current change function and a secondary current change function at the end of a preset switching cycle are obtained;

[0008] Performing Fourier decomposition on the primary current change function and the secondary current change function to obtain a primary DC component and various primary harmonic components of the primary current, and a secondary DC component and various secondary harmonic components of the secondary current;

[0009] Determining, based on the respective primary harmonic components, the respective secondary harmonic components, the actual primary current waveform, and the actual secondary current waveform, a selected primary harmonic component, a selected primary harmonic frequency corresponding to the selected primary harmonic component, a selected secondary harmonic component, and a selected secondary harmonic frequency corresponding to the selected secondary harmonic component;

[0010] Obtaining the primary AC resistance of the primary winding of the flyback transformer to be tested at the selected primary harmonic frequency, the primary DC resistance at the primary DC component, the secondary AC resistance of the secondary winding at the selected secondary harmonic frequency, and the secondary DC resistance at the secondary DC component;

[0011] The winding loss value of the flyback transformer to be tested is calculated based on the primary AC resistance, the secondary AC resistance, the selected primary harmonic component, the selected secondary harmonic component, the primary DC component, the secondary DC component, the primary DC resistance and the secondary DC resistance.

[0012] Furthermore, the above current calculation model is:

[0013]

[0014] N P *i p =N S *i S

[0015]

[0016]

[0017] Where V D represents the primary voltage, D represents the switch duty cycle, T represents the switch period, V o Indicates the secondary voltage, N indicates the turns ratio, L P Represents the primary inductance, i p Represents the primary current, N P Indicates the number of primary turns, N S Indicates the number of secondary turns, I o Indicates the average value of the secondary current, P indicates the output power, L S Represents the secondary inductance, i s Represents the secondary current, Δi S Represents the change in secondary current, and i represents the i-th switching cycle.

[0018] Furthermore, according to the above current calculation model, the primary current change function and the secondary current change function at the end of the preset switching period are obtained, including:

[0019] According to the current calculation model, a primary side current simulation programming model and a secondary side current simulation programming model are constructed.

[0020] The primary side current simulation programming model is simulated to obtain a primary side current change function at the end of a preset switching period.

[0021] The secondary side current simulation programming model is simulated to obtain a secondary side current change function at the end of a preset switching period.

[0022] Further, the selected primary side harmonic component, the selected primary side harmonic frequency corresponding to the selected primary side harmonic component, the selected secondary side harmonic component, and the selected secondary side harmonic frequency corresponding to the selected secondary side harmonic component are determined according to the each primary side harmonic component, the each secondary side harmonic component, the actual primary side current waveform, and the actual secondary side current waveform, and include:

[0023] The each primary side harmonic component is inversely Fourier transformed, and the primary side harmonic waveform after the inverse Fourier transformation is compared with the actual primary side current waveform to determine the first primary side harmonic frequency value corresponding to the highest degree of coincidence.

[0024] The primary side harmonic frequency corresponding to the each primary side harmonic component and not greater than the first primary side harmonic frequency value is taken as the selected primary side harmonic frequency, and the primary side harmonic component corresponding to the selected primary side harmonic frequency is taken as the selected primary side harmonic component.

[0025] The each secondary side harmonic component is inversely Fourier transformed, and the secondary side harmonic waveform after the inverse Fourier transformation is compared with the actual secondary side current waveform to determine the first secondary side harmonic frequency value corresponding to the highest degree of coincidence.

[0026] The secondary side harmonic frequency corresponding to the each secondary side harmonic component and not greater than the first secondary side harmonic frequency value is taken as the selected secondary side harmonic frequency, and the secondary side harmonic component corresponding to the selected secondary side harmonic frequency is taken as the selected secondary side harmonic component.

[0027] Further, the winding loss value of the to-be-tested flyback transformer is calculated according to the primary side alternating current resistance, the secondary side alternating current resistance, the selected primary side harmonic component, the selected secondary side harmonic component, the primary side direct current component, the secondary side direct current component, the primary side direct current resistance, and the secondary side direct current resistance, and include:

[0028] The first primary side winding loss value is calculated according to the primary side alternating current resistance and the selected primary side harmonic component.

[0029] According to the above primary side DC component and the above primary side DC resistance, a second primary side winding loss value is calculated;

[0030] According to the above secondary side AC resistance and the above selected secondary side harmonic component, a first secondary side winding loss value is calculated;

[0031] According to the above secondary side DC component and the above secondary side DC resistance, a second secondary side winding loss value is calculated;

[0032] The sum of the first primary side winding loss value, the second primary side winding loss value, the first secondary side winding loss value and the second secondary side winding loss value is calculated to obtain the winding loss value of the to-be-tested flyback transformer.

[0033] Further, after the winding loss value of the to-be-tested flyback transformer is calculated, the method further includes:

[0034] The winding loss value is compared with a preset early warning threshold value, and early warning is performed when the winding loss value is greater than the preset early warning threshold value.

[0035] On the basis of the above method embodiment, the application correspondingly provides a device embodiment;

[0036] The application provides a winding loss evaluation device of a flyback transformer, which comprises:

[0037] a data acquisition and model construction module, a current change function generation module, a Fourier decomposition module, a harmonic component and harmonic frequency selection module, a resistance acquisition module and a loss calculation module;

[0038] The data acquisition and model construction module is used for acquiring electrical data in a preset switching period, and actual primary side current waveforms and actual secondary side current waveforms of a to-be-tested flyback transformer under the electrical data, and constructing a current calculation model according to the electrical data; wherein the electrical data comprises a switching duty cycle, a secondary side voltage, a secondary side current average value and a secondary side current change amount.

[0039] The current change function generation module is used for obtaining a primary side current change function and a secondary side current change function at the end of the preset switching period according to the current calculation model.

[0040] The Fourier decomposition module is used for respectively performing Fourier decomposition on the primary side current change function and the secondary side current change function to obtain a primary side DC component and each primary side harmonic component of the primary side current, and a secondary side DC component and each secondary side harmonic component of the secondary side current.

[0041] The harmonic component and harmonic frequency selection module is configured to determine, according to the primary side harmonic components, the secondary side harmonic components, the actual primary side current waveform and the actual secondary side current waveform, the selected primary side harmonic component, the selected primary side harmonic frequency corresponding to the selected primary side harmonic component, the selected secondary side harmonic component and the selected secondary side harmonic frequency corresponding to the selected secondary side harmonic component.

[0042] The resistance acquisition module is configured to acquire the primary side AC resistance of the primary winding of the to-be-tested flyback transformer at the selected primary side harmonic frequency, the primary side DC resistance at the primary side DC component, the secondary side AC resistance of the secondary winding at the selected secondary side harmonic frequency and the secondary side DC resistance at the secondary side DC component.

[0043] The loss calculation module is configured to calculate the winding loss value of the to-be-tested flyback transformer according to the primary side AC resistance, the secondary side AC resistance, the selected primary side harmonic component, the selected secondary side harmonic component, the primary side DC component, the secondary side DC component, the primary side DC resistance and the secondary side DC resistance.

[0044] Further, the method further comprises a pre-warning module.

[0045] The pre-warning module is configured to compare the winding loss value with a preset pre-warning threshold, and perform pre-warning when the winding loss value is greater than the preset pre-warning threshold.

[0046] On the basis of the method embodiment, the application provides a terminal device embodiment.

[0047] The application provides a terminal device, which comprises a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, and the processor implements the winding loss evaluation method of the flyback transformer according to any one of the embodiments of the application when executing the computer program.

[0048] On the basis of the method embodiment, the application provides a storage medium embodiment.

[0049] The application provides a storage medium, which comprises a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, and the processor implements the winding loss evaluation method of the flyback transformer according to any one of the embodiments of the application when executing the computer program.

[0050] The embodiments of the application have the following beneficial effects:

[0051] The present invention provides a method, device, equipment and storage medium for evaluating the winding loss of a flyback transformer. The method comprises: first obtaining electrical data within a preset switching cycle, as well as the actual primary current waveform and the actual secondary current waveform of the flyback transformer to be tested under the above electrical data, and constructing a current calculation model based on the above electrical data; wherein the above electrical data include: switching duty cycle, secondary voltage, secondary current average value and secondary current change; then, according to the above current calculation model, obtaining the primary current change function and the secondary current change function at the end of the preset switching cycle; then, Fourier decomposition is performed on the above primary current change function and the above secondary current change function respectively to obtain the primary DC component and each primary harmonic component of the primary current, the secondary DC component and each secondary harmonic component of the secondary current; then, according to the above primary harmonic components, the above primary harmonic components and the above secondary harmonic components are obtained. The above-mentioned each secondary harmonic component, the above-mentioned actual primary current waveform and the above-mentioned actual secondary current waveform are used to determine the selected primary harmonic component, the selected primary harmonic frequency corresponding to the above-mentioned selected primary harmonic component, the selected secondary harmonic component and the selected secondary harmonic frequency corresponding to the above-mentioned selected secondary harmonic component; then obtain the primary AC resistance of the primary winding of the flyback transformer to be tested at the above-mentioned selected primary harmonic frequency, the primary DC resistance under the above-mentioned primary DC component, the secondary AC resistance of the secondary winding at the above-mentioned selected secondary harmonic frequency, and the secondary DC resistance under the above-mentioned secondary DC component; finally, according to the above-mentioned primary AC resistance, the above-mentioned secondary AC resistance, the above-mentioned selected primary harmonic component, the above-mentioned selected secondary harmonic component, the above-mentioned primary DC component, the above-mentioned secondary DC component, the above-mentioned primary DC resistance and the above-mentioned secondary DC resistance, calculate the winding loss value of the above-mentioned flyback transformer to be tested. Therefore, the present invention establishes a current calculation model to obtain the change function of the primary current and the secondary current of the flyback transformer, then performs Fourier decomposition on the current change function to determine the selected harmonic components and DC components of the current, measures the AC resistance of the flyback transformer at the harmonic frequency corresponding to the selected harmonic components, and the DC resistance at the primary DC component and the secondary DC component, and finally calculates the winding loss of the flyback transformer based on the AC resistance, DC resistance, the selected harmonic components of the current and the DC component, so that the winding loss of the flyback transformer can be quantitatively calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The figure is a flow chart of a method for evaluating the winding loss of a flyback transformer provided by one embodiment of the present invention.

[0053] Figure 2 Schematic diagram of the working principle of a flyback transformer provided by one embodiment of the present invention.

[0054] Figure 3Schematic diagram of a primary current simulation programming model provided by an embodiment of the present invention.

[0055] Figure 4 Schematic diagram of a secondary current simulation programming model provided by an embodiment of the present invention.

[0056] Figure 5 3 is a schematic diagram comparing the primary harmonic waveform and the actual primary current waveform provided by an embodiment of the present invention.

[0057] Figure 6 3 is a schematic diagram comparing the secondary harmonic waveform and the actual secondary current waveform provided by an embodiment of the present invention.

[0058] Figure 7 1 is a schematic diagram of a characteristic curve showing the relationship between primary AC resistance and frequency provided by an embodiment of the present invention.

[0059] Figure 8 FIG. 1 is a schematic diagram of a characteristic curve showing the relationship between the secondary side AC resistance and the frequency provided by an embodiment of the present invention.

[0060] Figure 9 1 is a schematic structural diagram of a flyback transformer winding loss evaluation device provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0061] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0062] like Figure 1 As shown, an embodiment of the present invention provides a method for evaluating the winding loss of a flyback transformer, including:

[0063] Step S101: Acquire electrical data within a preset switching cycle, as well as the actual primary current waveform and the actual secondary current waveform of the flyback transformer under test under the electrical data, and construct a current calculation model based on the electrical data; wherein the electrical data includes: switching duty cycle, secondary voltage, secondary current average value, and secondary current change;

[0064] Specifically, an oscilloscope is used to measure the actual primary current waveform and the actual secondary current waveform of the flyback transformer to be tested under the above electrical data.

[0065] In a preferred embodiment, the current calculation model is:

[0066] Specifically, in a sine half-wave with a period of 10ms, during the i-th switching cycle, the volt-second balance of the primary inductance is:

[0067]

[0068] In the primary side switch on range, there are:

[0069]

[0070] At the moment the switch is turned off, the energy on the primary side is transferred to the secondary side. This process satisfies the ampere-turn balance relationship, that is:

[0071] N P *i p =N S *i S

[0072] During the switch off period, the secondary side transfers energy to the grid:

[0073]

[0074] Where V D represents the primary voltage, D represents the switch duty cycle, T represents the switch period, V o Indicates the secondary voltage, N indicates the turns ratio, L P Represents the primary inductance, i p Represents the primary current, N P Indicates the number of primary turns, N S Indicates the number of secondary turns, I o Indicates the average value of the secondary current, P indicates the output power, L S Represents the secondary inductance, i s Represents the secondary current, Δi S Represents the change in secondary current, and i represents the i-th switching cycle.

[0075] Schematically, the working principle diagram of the flyback transformer is as follows Figure 2 As shown, Figure 2 Chinese N P and N S They are the primary winding and the secondary winding respectively. The inductance of the two windings on the primary and secondary sides of the flyback transformer are L P and L S . In switch S m conduction, and the conduction time T on = During DT, the DC voltage V D Added to the primary winding N P At both ends, the current i P Straight line rise, magnetic flux increases linearly, primary inductance L P Energy storage is performed, and the following formula is satisfied at this time:

[0076]

[0077] Among them, i P and φ increase linearly, if i P The initial value is i P0 , the increment is Δi P ;The initial value of φ is Increment Then we can get the following formula:

[0078]

[0079] In S m At the moment of shutdown, the current flowing through the primary winding will suddenly drop to zero, but the energy will not increase or decrease, and is always conserved. Therefore, the magnetic field energy stored in the transformer will not suddenly change, and the current in the secondary winding will suddenly change from 0 to a certain value. In other words, the magnetic energy stored in the primary winding Converted into magnetic energy of the secondary winding Let I S0 is the initial value of the current in the secondary winding. Since the inductance and the number of turns have the following relationship:

[0080]

[0081] And according to the law of conservation of energy, there is the following equation:

[0082]

[0083] Where, I Pmax Indicates the peak current of the primary inductor.

[0084] Then according to the above formula we can get: Pmax *N P =i S0 *N S , that is, the peak current of the primary inductor is converted into the current of the secondary inductor, and the ampere-turn balance relationship is satisfied during the mutation process. Then the initial current value of the secondary winding is:

[0085] In S m Turn off T off =(1-D)T, the current in the primary winding transfers to the secondary winding. The induced electromotive force in the secondary winding is positive at the top and negative at the bottom. At this time, diode D is turned on, the secondary voltage demagnetizes the transformer, and the secondary winding current and magnetic flux gradually decrease from the maximum value. During this process, the magnetic energy stored in the secondary inductor of the transformer is converted into electrical energy to supply power to the load, and also charges capacitor C. m After conduction, the following equation exists:

[0086]

[0087] And the flux change relationship is:

[0088]

[0089] Where, φ m Represents the core magnetic flux, φ O Indicates the initial value of the core magnetic flux.

[0090] In S m During the shutdown period, when the secondary diode is turned on, the following equation will be used:

[0091]

[0092] From the above equation, we can see that in S m During the shutdown period, the secondary current and flux decrease linearly. If during this period, the secondary current changes from i S0 Linearly decreases to i Smin , then we have:

[0093]

[0094] The reduction in magnetic flux is:

[0095]

[0096] Where Δφ′ represents the reduction in magnetic flux.

[0097] At the moment when the switch turns off again after the end of the off period, the current will suddenly change. Based on the principle that the ampere-turns before and after the change are equal, the following equation can be obtained:

[0098] i P0 =I Smin (N S / N P )

[0099] When the flyback transformer is in steady-state operation, the change in magnetic flux within one cycle is 0, from which we can obtain:

[0100]

[0101] The transformation ratio M is:

[0102]

[0103] The switching duty cycle is:

[0104]

[0105] In this preferred embodiment, a current calculation model is constructed based on various preset electrical data.

[0106] Step S102: obtaining a primary current variation function and a secondary current variation function at the end of a preset switching cycle according to the current calculation model;

[0107] In a preferred embodiment, according to the above current calculation model, the primary current change function and the secondary current change function at the end of the preset switching period are obtained, including:

[0108] According to the above current calculation model, a primary current simulation programming model and a secondary current simulation programming model are constructed;

[0109] Simulating the primary current simulation programming model to obtain a primary current variation function at the end of a preset switching cycle;

[0110] The secondary current simulation programming model is simulated to obtain a secondary current variation function at the end of a preset switching period.

[0111] Specifically, programming is performed in Mathcad software.

[0112] Schematically, the above primary current simulation programming model is as follows Figure 3 As shown, the secondary current simulation programming model is as follows Figure 4 As shown, after simulating the primary current simulation model, the primary current variation function at the end of the switching cycle is obtained; after simulating the secondary current simulation model, the secondary current variation function at the end of the switching cycle is obtained. It is worth noting that: at the end of the switching cycle, the secondary current may be equal to 0. This is because the preset average value of the secondary current is small. Therefore, the secondary current may have dropped to 0 before the end of the current switching cycle. The secondary current may also be greater than 0. This is because the preset average value of the secondary current is large. Therefore, at the end of the current switching cycle, the secondary current is still greater than 0. Different secondary currents will result in different current variation functions.

[0113] In this preferred embodiment, based on the current calculation model, the primary current variation function and the secondary current variation function at the end of the preset switching period are finally obtained.

[0114] Step S103: performing Fourier decomposition on the primary current variation function and the secondary current variation function to obtain a primary DC component and various primary harmonic components of the primary current, and a secondary DC component and various secondary harmonic components of the secondary current;

[0115] Specifically, the primary current change function and the secondary current change function are subjected to Fourier decomposition in a Mathcad program to obtain a DC component and various harmonic components.

[0116] Preferably, after Fourier decomposition, it is found that the harmonic components with larger values ​​are mainly concentrated in several harmonic components close to the switching frequency. As the frequency increases, the harmonic components have smaller values.

[0117] Step S104: determining a selected primary harmonic component, a selected primary harmonic frequency corresponding to the selected primary harmonic component, a selected secondary harmonic component, and a selected secondary harmonic frequency corresponding to the selected secondary harmonic component based on the respective primary harmonic components, the respective secondary harmonic components, the actual primary current waveform, and the actual secondary current waveform;

[0118] In a preferred embodiment, the determining of the selected primary harmonic component, the selected primary harmonic frequency corresponding to the selected primary harmonic component, the selected secondary harmonic component, and the selected secondary harmonic frequency corresponding to the selected secondary harmonic component based on the respective primary harmonic components, the respective secondary harmonic components, the actual primary current waveform, and the actual secondary current waveform includes:

[0119] Performing an inverse Fourier transform on each primary harmonic component, comparing the inverse Fourier transformed primary harmonic waveform with the actual primary current waveform, and determining the first primary harmonic frequency value corresponding to the highest degree of agreement;

[0120] Among the primary harmonic frequencies corresponding to the various primary harmonic components, the primary harmonic frequency that is not greater than the first primary harmonic frequency is used as the selected primary harmonic frequency, and the primary harmonic component corresponding to the selected primary harmonic frequency is used as the selected primary harmonic component;

[0121] Performing an inverse Fourier transform on each secondary harmonic component, comparing the secondary harmonic waveform after the inverse Fourier transform with the actual secondary current waveform, and determining the first secondary harmonic frequency value corresponding to the highest degree of agreement;

[0122] Among the secondary harmonic frequencies corresponding to each secondary harmonic component, the secondary harmonic frequency that is not greater than the above-mentioned first secondary harmonic frequency value is used as the above-mentioned selected secondary harmonic frequency, and at the same time, the secondary harmonic component corresponding to the above-mentioned selected secondary harmonic frequency is used as the above-mentioned selected secondary harmonic component.

[0123] Preferably, the decomposed harmonics are subjected to inverse Fourier transform. When the harmonic frequency is 12 times the switching frequency, i.e., 1.2 MHz, the actual current waveform can be well fitted. The comparison diagram of the primary harmonic waveform and the actual primary current waveform is shown in FIG. Figure 5 As shown, the comparison diagram of the secondary harmonic waveform and the actual secondary current waveform is shown in Figure 6 As shown. Figure 5 and Figure 6As can be seen from the figure, when the harmonic frequency is 12 times the switching frequency, the harmonic waveform after the inverse transformation is basically consistent with the actual current waveform, and thus the harmonic component not greater than 12 times the switching frequency can be used to calculate the winding loss.

[0124] In this preferred embodiment, the selected primary harmonic component, the selected primary harmonic frequency, the selected secondary harmonic component and the selected secondary harmonic frequency are determined according to the primary harmonic component, the secondary harmonic component, the actual primary current waveform and the actual secondary current waveform.

[0125] Step S105: obtaining the primary AC resistance of the primary winding of the to-be-tested flyback transformer at the selected primary harmonic frequency, the primary DC resistance of the primary winding at the primary DC component, the secondary AC resistance of the secondary winding at the selected secondary harmonic frequency, and the secondary DC resistance of the secondary winding at the secondary DC component;

[0126] Preferably, a small-signal element high-frequency characteristic measurement system, i.e., a high-precision impedance analyzer, is used to measure the AC resistance and DC resistance of the primary winding and the secondary winding of the flyback transformer respectively by using the sweep frequency method. As shown in FIG. 6, the measured relationship characteristic curve of the primary AC resistance of the primary winding and the frequency is shown in FIG. 6, and the relationship characteristic curve of the secondary AC resistance of the secondary winding and the frequency is shown in FIG. 7. Figure 7 Figure 8

[0127] Step S106: calculating the winding loss value of the to-be-tested flyback transformer according to the primary AC resistance, the secondary AC resistance, the selected primary harmonic component, the selected secondary harmonic component, the primary DC component, the secondary DC component, the primary DC resistance and the secondary DC resistance.

[0128] Specifically, in the case of low frequency or DC, the calculation of the winding loss is relatively simple, and the winding loss can be obtained by multiplying the square of the current effective value by the resistance. However, as the frequency increases, many complex factors must be considered in the calculation of the winding loss. The winding loss in the high-frequency case can be divided into three main parts: the loss caused by the skin effect; the loss caused by the proximity effect; and the loss caused by the influence of the air gap diffusion magnetic flux in the transformer and inductor with an air gap.

[0129] In a preferred embodiment, the calculation of the winding loss value of the to-be-tested flyback transformer according to the primary AC resistance, the secondary AC resistance, the selected primary harmonic component, the selected secondary harmonic component, the primary DC component, the secondary DC component, the primary DC resistance and the secondary DC resistance comprises:

[0130] ​​Calculating a first primary winding loss value based on the primary AC resistance and the selected primary harmonic components;

[0131] Specifically, the first primary winding loss value is calculated according to the following formula:

[0132]

[0133] Where, P P1 Indicates the loss value of the first primary winding, I P1aci represents the i-th selected primary harmonic component, R P1aci Represents the primary AC resistance corresponding to the i-th selected primary harmonic component.

[0134] Calculating a second primary winding loss value based on the primary DC component and the primary DC resistance;

[0135] Specifically, the second primary winding loss value is calculated according to the following formula:

[0136]

[0137] Where, P P2 Indicates the loss value of the second primary winding, I P2 Represents the primary DC component, R P2 Represents the primary DC resistance.

[0138] Calculating the first secondary winding loss value based on the secondary AC resistance and the selected secondary harmonic components;

[0139] Specifically, the loss value of the first secondary winding is calculated according to the following formula:

[0140]

[0141] Where, P S1 Indicates the loss value of the first secondary winding, I S1aci represents the i-th selected secondary harmonic component, R S1aci It represents the secondary AC resistance corresponding to the i-th selected secondary harmonic component.

[0142] Calculating the loss value of the second secondary winding according to the secondary DC component and the secondary DC resistance;

[0143] Specifically, the second secondary winding loss value is calculated according to the following formula:

[0144]

[0145] Specifically, P S2 Indicates the loss value of the second secondary winding, I S2 Represents the secondary DC component, RS2 Represents the secondary DC resistance.

[0146] The sum of the first primary winding loss value, the second primary winding loss value, the first secondary winding loss value, and the second secondary winding loss value is calculated to obtain the winding loss value of the flyback transformer to be tested.

[0147] In this preferred embodiment, the winding loss value of the flyback transformer to be tested is calculated based on the primary AC resistance, the secondary AC resistance, the selected primary harmonic component, the selected secondary harmonic component, the primary DC component, the secondary DC component, the primary DC resistance and the secondary DC resistance.

[0148] In another preferred embodiment, after calculating and obtaining the winding loss value of the flyback transformer to be tested, the method further includes:

[0149] The winding loss value is compared with a preset warning threshold, and a warning is issued when the winding loss value is greater than the preset warning threshold.

[0150] Preferably, the size of the preset warning threshold can be determined according to actual conditions.

[0151] In this preferred embodiment, the calculated winding loss value is compared with a preset warning threshold, and a warning is issued when the winding loss value is greater than the preset warning threshold.

[0152] Based on the above method embodiments, the present invention provides corresponding device embodiments.

[0153] like Figure 9 As shown, an embodiment of the present invention provides a flyback transformer winding loss evaluation device, comprising: a data acquisition and model building module, a current change function generation module, a Fourier decomposition module, a harmonic component and harmonic frequency selection module, a resistance acquisition module, and a loss calculation module;

[0154] The data acquisition and model building module is used to acquire electrical data within a preset switching cycle, as well as the actual primary current waveform and actual secondary current waveform of the flyback transformer under test under the electrical data, and to build a current calculation model based on the electrical data; wherein the electrical data includes: switching duty cycle, secondary voltage, secondary current average value, and secondary current change;

[0155] The current change function generating module is used to obtain the primary current change function and the secondary current change function at the end of the preset switching cycle according to the current calculation model;

[0156] The Fourier decomposition module is configured to perform Fourier decomposition on the primary side current variation function and the secondary side current variation function respectively to obtain a primary side direct current component and each primary side harmonic component of the primary side current, a secondary side direct current component and each secondary side harmonic component of the secondary side current.

[0157] The harmonic component and harmonic frequency selection module is configured to determine a selected primary side harmonic component, a selected primary side harmonic frequency corresponding to the selected primary side harmonic component, a selected secondary side harmonic component and a selected secondary side harmonic frequency corresponding to the selected secondary side harmonic component according to the each primary side harmonic component, the each secondary side harmonic component, the actual primary side current waveform and the actual secondary side current waveform.

[0158] The resistance acquisition module is configured to acquire a primary side alternating current resistance of the primary side winding of the to-be-tested flyback transformer at the selected primary side harmonic frequency, a primary side direct current resistance at the primary side direct current component, a secondary side alternating current resistance of the secondary side winding at the selected secondary side harmonic frequency and a secondary side direct current resistance at the secondary side direct current component.

[0159] The loss calculation module is configured to calculate the winding loss value of the to-be-tested flyback transformer according to the primary side alternating current resistance, the secondary side alternating current resistance, the selected primary side harmonic component, the selected secondary side harmonic component, the primary side direct current component, the secondary side direct current component, the primary side direct current resistance and the secondary side direct current resistance.

[0160] In a preferred embodiment, the device further comprises a pre-warning module.

[0161] The pre-warning module is configured to compare the winding loss value with a preset pre-warning threshold, and perform pre-warning when the winding loss value is greater than the preset pre-warning threshold.

[0162] It should be noted that the device embodiments described above are only schematic, wherein the modules described above as separate components can or can not be physically separate, and the components shown as modules can or can not be physical modules, i.e., they can be located in one place or distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment. In addition, the connection relationship between the modules in the device embodiment provided by the present application indicates that there is a communication connection between them, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement it without creative labor. The above schematic diagram is only an example of a flyback transformer winding loss evaluation device and does not constitute a limitation on a flyback transformer winding loss evaluation device, which can include more or fewer components than the diagram, or combine certain components, or different components.

[0163] On the basis of the above-mentioned method embodiment, the application correspondingly provides a terminal device embodiment.

[0164] Another embodiment of the application provides a terminal device, which comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and the processor executes the computer program to implement the above-mentioned anti-flyback transformer winding loss evaluation method of any one of the embodiments of the application.

[0165] For example, in this embodiment, the computer program can be divided into one or more modules, and the one or more modules are stored in the memory and executed by the processor to complete the application. The one or more modules can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program in the device.

[0166] The terminal device can be a desktop computer, a notebook computer, a palm computer, a cloud server, and other computing devices. The device can include, but is not limited to, a processor and a memory.

[0167] The processor can be a central processing module (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc. The processor is the control center of the device, and connects various parts of the device through various interfaces and lines.

[0168] The memory can be used to store the computer program and / or the modules, and the processor can realize various functions of the device by running or executing the computer program and / or the modules stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application program required by a function, and the like; in addition, the memory can include a high-speed random access memory, and can also include a nonvolatile memory, for example, a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one disk storage device, a flash memory device, or other volatile solid-state memory devices.

[0169] On the basis of the method embodiment, the application provides a storage medium embodiment.

[0170] Another embodiment of the application provides a storage medium, which includes a stored computer program, wherein the computer program controls a device where the storage medium is located to perform the winding loss evaluation method of the flyback transformer according to any one of the embodiments of the application when the computer program is running.

[0171] In this embodiment, the storage medium is a computer-readable storage medium, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, an executable file, or some intermediate form, etc. The computer-readable medium can include any entity or device capable of carrying the computer program code, a recording medium, a U disk, a mobile hard disk, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier wave signal, a telecommunication signal, a software distribution medium, etc.

[0172] Compared with the prior art, by implementing the various embodiments of the application, the winding loss of the flyback transformer can be quantitatively calculated.

[0173] The above is the preferred embodiment of the application, and it should be pointed out that, for those skilled in the art, without departing from the principles of the application, some improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the application.

Claims

1. A method for evaluating the winding loss of a flyback transformer, characterized in that: include: Acquire electrical data within a preset switching cycle, as well as actual primary current waveforms and actual secondary current waveforms of the flyback transformer under test under the electrical data, and construct a current calculation model based on the electrical data; wherein the electrical data includes: switching duty cycle, secondary voltage, secondary current average value, and secondary current change; According to the current calculation model, a primary current change function and a secondary current change function at the end of a preset switching period are obtained; Performing Fourier decomposition on the primary current change function and the secondary current change function respectively to obtain a primary DC component and various primary harmonic components of the primary current, and a secondary DC component and various secondary harmonic components of the secondary current; Determining, based on the primary harmonic components, the secondary harmonic components, the actual primary current waveform, and the actual secondary current waveform, a selected primary harmonic component, a selected primary harmonic frequency corresponding to the selected primary harmonic component, a selected secondary harmonic component, and a selected secondary harmonic frequency corresponding to the selected secondary harmonic component; Obtaining the primary AC resistance of the primary winding of the flyback transformer to be tested at the selected primary harmonic frequency, the primary DC resistance at the primary DC component, the secondary AC resistance of the secondary winding at the selected secondary harmonic frequency, and the secondary DC resistance at the secondary DC component; The winding loss value of the flyback transformer to be tested is calculated based on the primary AC resistance, the secondary AC resistance, the selected primary harmonic component, the selected secondary harmonic component, the primary DC component, the secondary DC component, the primary DC resistance, and the secondary DC resistance.

2. The method for evaluating the winding loss of a flyback transformer according to claim 1, wherein: The current calculation model is: N P *i p =N S *i S Where V D represents the primary voltage, D represents the switch duty cycle, T represents the switch period, V o Indicates the secondary voltage, N indicates the turns ratio, L P Represents the primary inductance, i p Represents the primary current, N P Indicates the number of primary turns, N S Indicates the number of secondary turns, I o Indicates the average value of the secondary current, P indicates the output power, L S Represents the secondary inductance, i s Represents the secondary current, Δi S Represents the change in secondary current, and i represents the i-th switching cycle.

3. The method for evaluating the winding loss of a flyback transformer according to claim 2, wherein: According to the current calculation model, a primary current change function and a secondary current change function at the end of a preset switching period are obtained, including: According to the current calculation model, a primary current simulation programming model and a secondary current simulation programming model are constructed; simulating the primary current simulation programming model to obtain a primary current variation function at the end of a preset switching cycle; The secondary current simulation programming model is simulated to obtain a secondary current variation function at the end of a preset switching period.

4. The method for evaluating the winding loss of a flyback transformer according to claim 3, wherein: The determining, based on the respective primary harmonic components, the respective secondary harmonic components, the actual primary current waveform, and the actual secondary current waveform, a selected primary harmonic component, a selected primary harmonic frequency corresponding to the selected primary harmonic component, a selected secondary harmonic component, and a selected secondary harmonic frequency corresponding to the selected secondary harmonic component comprises: Performing an inverse Fourier transform on each primary harmonic component, comparing the inverse Fourier transformed primary harmonic waveform with the actual primary current waveform, and determining the first primary harmonic frequency value corresponding to the highest degree of agreement; Among the primary harmonic frequencies corresponding to the primary harmonic components, the primary harmonic frequency that is not greater than the first primary harmonic frequency value is used as the selected primary harmonic frequency, and the primary harmonic component corresponding to the selected primary harmonic frequency is used as the selected primary harmonic component; Performing an inverse Fourier transform on each secondary harmonic component, comparing the secondary harmonic waveform after the inverse Fourier transform with the actual secondary current waveform, and determining the first secondary harmonic frequency value corresponding to the highest degree of agreement; Among the secondary harmonic frequencies corresponding to the various secondary harmonic components, the secondary harmonic frequency that is not greater than the first secondary harmonic frequency value is used as the selected secondary harmonic frequency, and the secondary harmonic component corresponding to the selected secondary harmonic frequency is used as the selected secondary harmonic component.

5. The method for evaluating the winding loss of a flyback transformer according to claim 4, wherein: The calculating of the winding loss value of the flyback transformer to be tested according to the primary AC resistance, the secondary AC resistance, the selected primary harmonic component, the selected secondary harmonic component, the primary DC component, the secondary DC component, the primary DC resistance, and the secondary DC resistance includes: Calculating a first primary winding loss value based on the primary AC resistance and the selected primary harmonic component; Calculating a second primary winding loss value according to the primary DC component and the primary DC resistance; Calculating a first secondary winding loss value based on the secondary AC resistance and the selected secondary harmonic component; Calculating a second secondary winding loss value according to the secondary DC component and the secondary DC resistance; The sum of the first primary winding loss value, the second primary winding loss value, the first secondary winding loss value, and the second secondary winding loss value is calculated to obtain the winding loss value of the flyback transformer to be tested.

6. The method for evaluating the winding loss of a flyback transformer according to claim 5, wherein: After calculating the winding loss value of the flyback transformer to be tested, the method further includes: The winding loss value is compared with a preset warning threshold, and a warning is issued when the winding loss value is greater than the preset warning threshold.

7. A flyback transformer winding loss evaluation device, characterized in that: include: Data acquisition and model building module, current change function generation module, Fourier decomposition module, harmonic component and harmonic frequency selection module, resistance acquisition module and loss calculation module; The data acquisition and model building module is configured to acquire electrical data within a preset switching cycle, as well as the actual primary current waveform and the actual secondary current waveform of the flyback transformer to be tested under the electrical data, and to build a current calculation model based on the electrical data; wherein the electrical data includes: switching duty cycle, secondary voltage, secondary current average value, and secondary current change; The current change function generating module is configured to obtain a primary current change function and a secondary current change function at the end of a preset switching cycle according to the current calculation model; The Fourier decomposition module is used to perform Fourier decomposition on the primary current change function and the secondary current change function respectively to obtain the primary DC component and each primary harmonic component of the primary current, and the secondary DC component and each secondary harmonic component of the secondary current; The harmonic component and harmonic frequency selection module is used to determine a selected primary harmonic component, a selected primary harmonic frequency corresponding to the selected primary harmonic component, a selected secondary harmonic component, and a selected secondary harmonic frequency corresponding to the selected secondary harmonic component based on the respective primary harmonic components, the respective secondary harmonic components, the actual primary current waveform, and the actual secondary current waveform; The resistance acquisition module is used to obtain the primary AC resistance of the primary winding of the flyback transformer to be tested at the selected primary harmonic frequency, the primary DC resistance at the primary DC component, the secondary AC resistance of the secondary winding at the selected secondary harmonic frequency, and the secondary DC resistance at the secondary DC component; The loss calculation module is used to calculate the winding loss value of the flyback transformer to be tested based on the primary AC resistance, the secondary AC resistance, the selected primary harmonic component, the selected secondary harmonic component, the primary DC component, the secondary DC component, the primary DC resistance and the secondary DC resistance.

8. The flyback transformer winding loss evaluation device according to claim 7, characterized in that: Also includes: Early warning module; The early warning module is used to compare the winding loss value with a preset early warning threshold, and issue an early warning when the winding loss value is greater than the preset early warning threshold.

9. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, a method for evaluating the winding loss of a flyback transformer according to any one of claims 1 to 6 is implemented.

10. A storage medium, characterized in that: The storage medium includes a stored computer program, wherein when the computer program is executed, the device where the storage medium is located is controlled to execute the flyback transformer winding loss evaluation method according to any one of claims 1 to 6.

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