Flyback transformer winding loss evaluation method, device and equipment and storage medium

Abstract

The invention discloses a flyback transformer winding loss evaluation method, device and equipment and a storage medium, and the method comprises the steps: obtaining electrical data in a preset switching period, and the actual primary side current waveform and the actual secondary side current waveform of a to-be-tested flyback transformer under the electrical data, and constructing a current calculation model, obtaining a primary side current change function and a secondary side current change function; fourier decomposition is carried out on the primary side current change function and the secondary side current change function to obtain a primary side direct current component, a primary side harmonic component, a secondary side direct current component and a secondary side harmonic component; then determining a selected primary side harmonic component, a selected primary side harmonic frequency, a selected secondary side harmonic component and a selected secondary side harmonic frequency; the primary side alternating current resistance, the primary side direct current resistance, the secondary side alternating current resistance and the secondary side direct current resistance of the flyback transformer are obtained; and finally, calculating the winding loss value of the flyback transformer to be measured. By implementing the method, 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 electric energy transmitted to the grid by the photovoltaic inverter will always be less than the DC electric energy generated by the solar cell. This is because there are losses in the working process of the inverter, and the loss composition includes active device losses and passive device losses. Active devices include drive circuits and semiconductor devices such as Mosfet tubes and diodes, and passive devices include transformers, filter inductors and capacitors. These devices will also consume energy during the energy transmission process due to the influence of various parameters. The loss of the flyback transformer winding accounts for a considerable proportion of the overall loss of the photovoltaic inverter. If you want to improve the working efficiency of the photovoltaic inverter, you must have a deep understanding of the working state of the transformer winding and conduct a detailed analysis of the causes of the flyback transformer winding loss.

[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 winding loss of the flyback transformer.

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

[0006] Obtain 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 construct a current calculation model based on the above electrical data; wherein the above electrical data include: switch 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 respectively to obtain a primary DC component and each primary harmonic component of the primary current, and a secondary DC component and each secondary harmonic component of the secondary current;

[0009] Determine, according to the above-mentioned primary harmonic components, the above-mentioned secondary harmonic components, the above-mentioned actual primary current waveform and the above-mentioned actual secondary current waveform, a selected primary harmonic component, a selected primary harmonic frequency corresponding to the above-mentioned selected primary harmonic component, a selected secondary harmonic component and a selected secondary harmonic frequency corresponding to the above-mentioned 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 above-mentioned flyback transformer to be tested is calculated based on 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.

[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 represents the secondary voltage, N represents 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 represents the average value of the secondary current, P represents 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 cycle are obtained, including:

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

[0020] Simulating the primary current simulation programming model to obtain a primary current variation function at the end of a preset switching cycle;

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

[0022] Further, the above-mentioned determining, based on the above-mentioned primary harmonic components, the above-mentioned secondary harmonic components, the above-mentioned actual primary current waveform, and the above-mentioned actual secondary current waveform, 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 includes:

[0023] 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;

[0024] 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;

[0025] 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;

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

[0027] Further, 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, including:

[0028] The first primary winding loss value is calculated based on the primary AC resistance and the selected primary harmonic component;

[0029] The loss value of the second primary winding is calculated based on the primary DC component and the primary DC resistance;

[0030] The loss value of the first secondary winding is calculated based on the secondary AC resistance and the selected secondary harmonic component;

[0031] The loss value of the second secondary winding is calculated based on the secondary DC component and the secondary DC resistance;

[0032] 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.

[0033] Furthermore, after calculating the winding loss value of the flyback transformer to be tested, the method further includes:

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

[0035] Based on the above method embodiment, the present invention provides a corresponding device embodiment;

[0036] The present invention provides a flyback transformer winding loss evaluation device, comprising:

[0037] 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;

[0038] 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 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: switch duty cycle, secondary voltage, secondary current average value and secondary current change;

[0039] 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;

[0040] The Fourier decomposition module is used to perform Fourier decomposition on the primary current change function and the secondary current change function to obtain a primary DC component and each primary harmonic component of the primary current, and a secondary DC component and each secondary harmonic component of the secondary current;

[0041] The harmonic component and harmonic frequency selection module is used to determine 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 according to the primary harmonic components, the secondary harmonic components, the actual primary current waveform and the actual secondary current waveform;

[0042] 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;

[0043] The above-mentioned loss calculation module is used to calculate the winding loss value of the above-mentioned flyback transformer to be tested based on 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.

[0044] Furthermore, it also includes: an early warning module;

[0045] The above-mentioned early warning module is used to compare the above-mentioned winding loss value with the preset early warning threshold value, and to issue an early warning when the above-mentioned winding loss value is greater than the above-mentioned preset early warning threshold value.

[0046] Based on the above method embodiment, the present invention provides a terminal device embodiment;

[0047] The present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the above-mentioned method for evaluating the winding loss of a flyback transformer according to any embodiment of the present invention.

[0048] Based on the above method embodiment, the present invention provides a storage medium embodiment;

[0049] The present invention provides a storage medium, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, a method for evaluating the winding loss of a flyback transformer described in any embodiment of the present invention is implemented.

[0050] The embodiments of the present invention 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 electrical data, and constructing a current calculation model based on the electrical data; wherein the electrical data comprises: a switching duty cycle, a secondary voltage, an average secondary current value and a secondary current change; then, according to the current calculation model, obtaining a primary current change function and a secondary current change function at the end of the preset switching cycle; then, respectively, performing Fourier decomposition on the primary current change function and the secondary current change function to obtain a primary DC component and each primary harmonic component of the primary current, and a secondary DC component and each secondary harmonic component of the secondary current; then, according to the each primary harmonic component, the upper 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 are determined according to the above-mentioned secondary harmonic components, the above-mentioned actual primary current waveform, and the above-mentioned actual secondary current waveform; then 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 are obtained; 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, the winding loss value of the above-mentioned flyback transformer to be tested is calculated. 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 the DC component 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, the 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 It is a flow chart of a method for evaluating the winding loss of a flyback transformer provided in one embodiment of the present invention.

[0053] Figure 2 It is a schematic diagram of the working principle of a flyback transformer provided by an embodiment of the present invention.

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

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

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

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

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

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

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

[0061] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0063] Step S101: acquiring electrical data within a preset switching cycle, and 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 according to the above electrical data; wherein the above electrical data include: switch 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, at the i-th switching cycle, according to the volt-second balance of the primary inductance:

[0067]

[0068] In the primary switch on interval, 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 represents the secondary voltage, N represents 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 represents the average value of the secondary current, P represents 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 Medium P and N S They are the primary winding and the secondary winding respectively. The inductances of the two windings on the primary and secondary sides of the flyback transformer are L P and L S . In switch S m Turn on, 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 up, 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 neither increase nor 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] In the formula, 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 of the primary winding is transferred to the secondary side. The induced electromotive force of the secondary winding is positive at the top and negative at the bottom. At this time, the 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. In this process, the magnetic energy stored in the secondary inductance of the transformer is converted into electrical energy to supply power to the load, and also charges the capacitor C. Since S m After conduction, there is the following equation:

[0086]

[0087] And the flux change relationship is:

[0088]

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

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

[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 flux reduction is:

[0095]

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

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

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

[0099] When the flyback transformer works in steady state, the change of magnetic flux in one cycle is 0, so we can get:

[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 cycle 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 cycle.

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

[0112] Schematically, the above primary current simulation programming model is as follows Figure 3 As shown in the figure, 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 secondary current average value is small. Therefore, before the current switching cycle ends, the secondary current may have dropped to 0; the secondary current may also be greater than 0. This is because the preset secondary current average value 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 cycle are finally obtained.

[0114] Step S103: performing Fourier decomposition on the primary current change function and the secondary current change function respectively to obtain a primary DC component and each primary harmonic component of the primary current, and a secondary DC component and each secondary harmonic component 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 component values ​​decrease.

[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 according to the primary harmonic components, the secondary harmonic components, the actual primary current waveform, and the actual secondary current waveform;

[0118] In a preferred embodiment, the above-mentioned determination 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 according to the above-mentioned primary harmonic components, the above-mentioned secondary harmonic components, the above-mentioned actual primary current waveform, and the above-mentioned 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 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;

[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 first secondary harmonic frequency value is taken as the selected secondary harmonic frequency, and the secondary harmonic component corresponding to the selected secondary harmonic frequency is taken as the 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 schematic diagram of the comparison between the primary harmonic waveform and the actual primary current waveform is shown in FIG. Figure 5 As shown in the figure, the comparison diagram of the secondary harmonic waveform and the actual secondary current waveform is as follows Figure 6 As shown. Figure 5 and Figure 6It can be seen that when the harmonic frequency is 12 times the switching frequency, the harmonic waveform after inverse transformation is basically consistent with the actual current waveform. Therefore, 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 based on each primary harmonic component, each 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 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;

[0126] Preferably, a high-precision impedance analyzer, a high-frequency characteristic measurement system for small signal components, can be used to measure the AC resistance and DC resistance of the primary winding and the secondary winding of the flyback transformer by frequency sweeping. The characteristic curve of the relationship between the primary AC resistance and the frequency of the measured primary winding is as follows: Figure 7 As shown, the characteristic curve of the relationship between the secondary side AC resistance and frequency of the secondary winding is as follows Figure 8 shown.

[0127] Step S106: Calculate 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.

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

[0129] In a 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, including:

[0130] The first primary winding loss value is calculated based on the primary AC resistance and the selected primary harmonic component;

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

[0132]

[0133] Where P P1 Represents 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] The loss value of the second primary winding is calculated 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] The loss value of the first secondary winding is calculated based on the secondary AC resistance and the selected secondary harmonic component;

[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 Represents the secondary AC resistance corresponding to the i-th selected secondary harmonic component.

[0142] The loss value of the second secondary winding is calculated based on the secondary DC component and the secondary DC resistance;

[0143] Specifically, the loss value of the second secondary winding 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 the winding loss value of the flyback transformer to be tested, the method further includes:

[0149] The above winding loss value is compared with the preset warning threshold, and a warning is issued when the above winding loss value is greater than the above 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 embodiment, the present invention provides a corresponding device embodiment.

[0153] like Fig. 9 As shown, an embodiment of the present invention provides a flyback transformer winding loss evaluation device, including: 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 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: switch 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 used to perform Fourier decomposition on the primary current change function and the secondary current change function to obtain a primary DC component and each primary harmonic component of the primary current, and a secondary DC component and each secondary harmonic component of the secondary current;

[0157] The harmonic component and harmonic frequency selection module is used to determine 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 according to the primary harmonic components, the secondary harmonic components, the actual primary current waveform and the actual secondary current waveform;

[0158] 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;

[0159] The above-mentioned loss calculation module is used to calculate the winding loss value of the above-mentioned flyback transformer to be tested based on 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.

[0160] In a preferred embodiment, it also includes: an early warning module;

[0161] The above-mentioned early warning module is used to compare the above-mentioned winding loss value with the preset early warning threshold value, and to issue an early warning when the above-mentioned winding loss value is greater than the above-mentioned preset early warning threshold value.

[0162] It should be noted that the device embodiments described above are merely schematic, wherein the modules described above as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the accompanying drawings of the device embodiments provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art can understand and implement it without creative work. The above schematic diagram is only an example of a flyback transformer winding loss assessment device, and does not constitute a limitation on a flyback transformer winding loss assessment device, and may include more or fewer components than shown in the figure, or a combination of certain components, or different components.

[0163] Based on the above method item embodiments, the present invention provides corresponding terminal device item embodiments.

[0164] Another embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, it implements a flyback transformer winding loss evaluation method described in any embodiment of the present invention.

[0165] Exemplarily, in this embodiment, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to implement the present invention. The one or more module elements may be a series of computer program instruction segments capable of implementing specific functions, which are used to describe the execution process of the computer program in the device;

[0166] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The device may include, but is not limited to, a processor, a memory;

[0167] The processor referred to herein may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The above-mentioned processor is the control center of the above-mentioned device, and uses various interfaces and lines to connect various parts of the entire device;

[0168] The above-mentioned memory can be used to store the above-mentioned computer programs and / or modules. The above-mentioned processor realizes various functions of the above-mentioned device by running or executing the computer programs and / or modules stored in the above-mentioned memory, and calling the data stored in the memory. The above-mentioned 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 required for a function, etc.; in addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0169] Based on the above method item embodiments, the present invention provides a corresponding storage medium item embodiment.

[0170] Another embodiment of the present invention provides a storage medium, the storage medium includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute a flyback transformer winding loss evaluation method described in any embodiment of the present invention.

[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 may be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0172] Compared with the prior art, by implementing the above-mentioned embodiments of the present invention, the winding loss of the flyback transformer can be quantitatively calculated.

[0173] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

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 the actual primary current waveform and the actual secondary current waveform of the flyback transformer to be tested under the electrical data, and construct a current calculation model based on the electrical data; wherein the electrical data includes: switch 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 cycle 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 each primary harmonic component of the primary current, and a secondary DC component and each secondary harmonic component of the secondary current; Determine, according to 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. A flyback transformer winding loss evaluation method according to claim 1, characterized in that: 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 represents the secondary voltage, N represents 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 represents the average value of the secondary current, P represents 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. A flyback transformer winding loss evaluation method according to claim 2, characterized in that: According to the current calculation model, a primary current change function and a secondary current change function at the end of a preset switching cycle 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 cycle.

4. A flyback transformer winding loss evaluation method according to claim 3, characterized in that: Determining, according to 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 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 taken as the selected secondary harmonic frequency, and the secondary harmonic component corresponding to the selected secondary harmonic frequency is taken as the selected secondary harmonic component.

5. A flyback transformer winding loss evaluation method according to claim 4, characterized in that: The step of calculating 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 according to 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 according to 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. A flyback transformer winding loss evaluation method according to claim 5, characterized in that: After the winding loss value of the flyback transformer to be tested is calculated, 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 used to acquire electrical data within a preset switching cycle, and the actual primary current waveform and the actual secondary current waveform of the flyback transformer to be tested under the electrical data, and build a current calculation model based on the electrical data; wherein the electrical data includes: switch duty cycle, secondary voltage, secondary current average value and secondary current change; 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 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 a primary DC component and each primary harmonic component of the primary current, and a secondary DC component and each secondary harmonic component of the secondary current; The harmonic component and harmonic frequency selection module is used to determine 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 according to the various primary harmonic components, the various secondary harmonic components, the actual primary current waveform and the actual secondary current waveform; The resistance acquisition module is used to acquire 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 invention 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 as claimed in 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 a flyback transformer winding loss evaluation method as described in any one of claims 1 to 6.

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