A method for determining the losses of high-frequency transformers in high-frequency chain AC-DC matrix converters.

Abstract

This application provides a method for determining the losses of a high-frequency transformer in a high-frequency AC-DC matrix converter. The method includes determining the first, second, and third power line voltages of the AC power supply to the matrix converter; calculating the primary and secondary currents of the transformer based on these voltages, the leakage inductance of the high-frequency transformer, the transformer's turns ratio, the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and the following stage voltage; calculating the AC winding coefficient based on the winding parameters; calculating the winding losses based on the primary and secondary currents and the AC winding coefficient; calculating the core losses based on the preceding and following stage voltages, the number of winding turns, and the core parameters; and adding the winding losses and core losses to obtain the losses of the high-frequency transformer. This method avoids the negative impact of the non-sinusoidal characteristics of voltage and current on loss calculations during actual operation, resulting in more accurate losses.

Description

Technical Field

[0001] This application relates to the field of transformer technology, and more specifically, to a method, electronic device, and storage medium for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter. Background Technology

[0002] The high-frequency chain AC-DC matrix converter, as a member of the isolated AC-DC converter family, is a derived topology of the matrix converter. It achieves mutual conversion between AC and DC by employing a bidirectional switch array. The high-frequency transformer plays a crucial role in the high-frequency chain AC-DC matrix converter, providing voltage transformation and electrical isolation, and significantly impacting its efficiency and power density.

[0003] To improve the efficiency and power density of high-frequency chain AC-DC matrix converters, it is necessary to accurately determine the losses of the high-frequency transformer. Among these losses, the winding losses of the high-frequency transformer are one of the most significant factors affecting energy conversion and transmission efficiency, making their analysis crucial. In conventional DC-DC converters, the high-frequency transformer is typically excited by a symmetrical square wave or sine wave, and traditional loss calculation methods are relatively accurate for this situation. However, due to the unique topology of high-frequency chain AC-DC matrix converters, the excitation signal on the high-frequency transformer exhibits characteristics such as high frequency, time-varying amplitude, and irregularity. This is far more complex than the symmetrical square wave or sine wave excitation of the high-frequency transformer in conventional DC-DC converters. Existing loss calculation modeling methods cannot obtain accurate loss results. Summary of the Invention

[0004] Embodiments of this application are proposed in view of the above-mentioned problems. Embodiments of this application provide a method, electronic device, and storage medium for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter. This invention discloses a method for determining the losses of a high-frequency transformer in a high-frequency AC-DC matrix converter, comprising: determining, according to the modulation strategy of the matrix converter, a first power line voltage with positive polarity and the largest amplitude, a second power line voltage with positive polarity and the second largest amplitude, and a third power line voltage with positive polarity and the smallest amplitude in each sector of the AC power supply voltage variation diagram of the matrix converter; calculating the primary and secondary currents of the high-frequency transformer based on the first, second, and third power line voltages, the leakage inductance of the high-frequency transformer, the transformation ratio of the high-frequency transformer, the voltage of the subsequent stage of the matrix converter, and the pulse width of the voltage with the largest amplitude among the voltages of the preceding stage of the matrix converter; calculating the AC winding coefficient of the high-frequency transformer based on the winding parameters of the high-frequency transformer; calculating the winding losses of the high-frequency transformer based on the primary current, secondary current, and AC winding coefficient; calculating the core losses of the high-frequency transformer based on the voltage of the preceding stage, the voltage of the subsequent stage, and the number of turns and core parameters of the high-frequency transformer; and adding the winding losses and core losses to obtain the losses of the high-frequency transformer.

[0005] For example, calculating the primary and secondary currents of a high-frequency transformer includes: calculating the primary magnetizing current of the high-frequency transformer based on the magnetizing inductance of the high-frequency transformer, the pulse width of the maximum amplitude voltage among the first, second, and third power supply line voltages, and the preceding stage voltages; calculating the equivalent secondary magnetizing current of the high-frequency transformer based on the magnetizing inductance of the high-frequency transformer, the subsequent stage voltage of the matrix converter, and the transformation ratio of the high-frequency transformer; calculating the primary winding harmonic current and secondary winding harmonic current of the high-frequency transformer based on the first, second, and third power supply line voltages, the leakage inductance of the high-frequency transformer, the transformation ratio of the high-frequency transformer, the subsequent stage voltage of the matrix converter, and the pulse width of the maximum amplitude voltage among the preceding stage voltages of the matrix converter; and calculating the primary and secondary currents of the high-frequency transformer based on the primary magnetizing current, the equivalent secondary magnetizing current, the primary winding harmonic current, and the secondary winding harmonic current.

[0006] For example, calculating the primary winding current of a high-frequency transformer includes: calculating the primary winding harmonic current i of the kth harmonic according to the following formula. L，k Amplitude:

[0007] Where L represents the leakage inductance of the high-frequency transformer, k represents the harmonic order, and n represents the transformation ratio of the high-frequency transformer. u represents the phase difference between the preceding and following voltage stages. max Indicates the first power supply line voltage, u med Indicates the second power supply line voltage, umin d1 represents the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and f represents the voltage of the third power supply line. s This represents the characteristic frequency of the matrix transformer.

[0008] For example, calculating the primary excitation current of a high-frequency transformer includes: calculating c according to the following formula. mp，k and c mp，k The modulus is determined to be the primary excitation current i of the kth harmonic. mp，k Amplitude:

[0009] Among them, L m This represents the magnetizing inductance of a high-frequency transformer, k represents the harmonic order, and u... max Indicates the first power supply line voltage, u med Indicates the second power supply line voltage, u min The voltage of the third power supply line is represented by j0, and j0 indicates that the imaginary impedance angle is 0 in the initial state.

[0010] For example, calculating the equivalent secondary excitation current of a high-frequency transformer includes calculating c' according to the following formula. ms，k and c' ms，k The modulus is determined as the equivalent secondary excitation current i' of the kth harmonic. ms，k Amplitude:

[0011] Among them, L m This represents the magnetizing inductance of the high-frequency transformer, k represents the harmonic order, and n represents the transformer's turns ratio. f represents the phase difference between the preceding voltage and the following voltage of the matrix converter. s This represents the characteristic frequency of the matrix transformer.

[0012] For example, calculating the core loss of a high-frequency transformer includes: calculating the peak magnetic flux density of the high-frequency transformer based on the number of winding turns, core cross-sectional area, first power line voltage, second power line voltage, pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and characteristic frequency of the matrix converter; and calculating the core loss based on the peak magnetic flux density and the loss coefficient of the core material of the high-frequency transformer.

[0013] For example, calculating the core loss based on the peak magnetic flux density and the loss coefficient of the core material of the high-frequency transformer includes: using the modified Steinmetz equation, the generalized Steinmetz equation, and / or the waveform similarity coefficient Steinmetz equation to calculate the core loss based on the peak magnetic flux density and the loss coefficient of the core material of the high-frequency transformer.

[0014] For example, calculating the peak magnetic flux density of a high-frequency transformer includes:

[0015] The peak magnetic flux density of the primary side of a high-frequency transformer can be calculated using the following formula:

[0016]

[0017] The peak magnetic flux density on the secondary side of a high-frequency transformer can be calculated using the following formula:

[0018]

[0019] Among them, B m，p B represents the peak magnetic flux density on the primary side. m，s T represents the peak magnetic flux density on the secondary side. s Indicates the control period, N represents the number of turns in the high-frequency transformer winding, S represents the core cross-sectional area, and u max Indicates the first power supply line voltage, u med d1 represents the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and u represents the voltage of the second power supply line. s This represents the voltage of the subsequent stage of the matrix converter. This indicates the phase difference between the preceding voltage and the following voltage.

[0020] According to another aspect of this application, the present invention also discloses an electronic device, including a processor and a memory, wherein the memory stores computer program instructions, which, when executed by the processor, are used to perform the method described above for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter.

[0021] According to another aspect of this application, the present invention also discloses a storage medium storing program instructions that, when executed, perform the method described above for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter.

[0022] In the above technical solution, the losses of the high-frequency transformer in the high-frequency chain AC-DC matrix converter are determined based on the superposition principle. First, the first, second, and third power line voltages, which are superimposed and equivalent to the preceding voltages of the matrix converter, are determined. Then, based on these power line voltages, the primary circuit and secondary current of the high-frequency transformer are determined, and the winding losses of the high-frequency transformer are calculated. The core loss of the high-frequency transformer is calculated based on the preceding voltages of the matrix converter, the number of turns in the high-frequency transformer windings, and the core parameters. Finally, based on the winding losses and core losses, the total loss of the high-frequency transformer is obtained. This solution avoids the negative impact of the non-sinusoidal characteristics of voltage and current on the calculation of high-frequency transformer losses during actual operation, resulting in more accurate loss determination. Attached Figure Description

[0023] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0024] Figure 1 A schematic diagram of the topology of a high-frequency chain AC-DC matrix converter according to an embodiment of this application is shown;

[0025] Figure 2 It shows Figure 1 The equivalent circuit diagram of the high-frequency chain AC-DC matrix converter is shown below;

[0026] Figure 3 A schematic flowchart of a method for determining the loss of a high-frequency transformer in a high-frequency chain AC-DC matrix converter according to an embodiment of the present invention is shown.

[0027] Figure 4 It shows Figure 1 The diagram shows the voltage variation sector of the AC power supply for the high-frequency chain AC-DC matrix converter.

[0028] Figure 5 It shows Figure 1 The high-frequency chain AC-DC matrix converter shown has a front-end voltage u. p The voltage of the subsequent stage u s Waveform diagram of inductor current;

[0029] Figure 6 An embodiment of the present invention is shown. Figure 5 The preceding voltage u shown p and subsequent voltage u s A waveform diagram showing the first power line voltage, the second power line voltage, and the third power line voltage;

[0030] Figure 7 It shows Figure 6 The diagram shown is the equivalent circuit diagram of the disassembled high-frequency AC-DC matrix converter.

[0031] Figure 8A It shows Figure 1 A simplified schematic diagram of the high-frequency transformer in a high-frequency chain AC-DC matrix converter is shown.

[0032] Figure 8B It shows Figure 1 The cross-sectional view of the Litz wire winding of the high-frequency transformer in the high-frequency chain AC-DC matrix converter is shown.

[0033] Figure 9 It shows Figure 1 A schematic diagram of the cross-section of the high-frequency transformer Litz line in the high-frequency AC-DC matrix converter shown.

[0034] Figure 10 A schematic diagram of an auxiliary function f(t) according to an embodiment of the present invention is shown;

[0035] Figure 11 A schematic diagram of an auxiliary function g(t) according to an embodiment of the present invention is shown;

[0036] Figure 12 An embodiment of the present invention is shown. Figure 1 The diagram shown is the equivalent circuit diagram of the high-frequency AC-DC matrix converter considering the excitation inductance.

[0037] Figure 13 A schematic diagram showing the relationship between the front-end voltage and the rear-end voltage of a high-frequency transformer according to an embodiment of the present invention and the magnetic induction intensity is shown.

[0038] The above figures include the following reference numerals:

[0039] 110. Three-phase AC power supply; 120. Grid-side filter; 131. Matrix switch circuit; 132. High-frequency transformer; 132A. Transformer core; 132B. Transformer winding; 133. Full-bridge circuit; 140. DC-side filter; 150. Storage battery. Detailed Implementation

[0040] In the following description, numerous details are provided to enable a thorough understanding of this application. However, those skilled in the art will appreciate that the following description merely illustrates preferred embodiments of the application by way of example only. Furthermore, to avoid confusion with this application, some technical features well-known in the art have not been described in detail.

[0041] This invention discloses a method for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter. Based on the internal operating mechanism of the high-frequency chain AC-DC matrix converter and the electromagnetic characteristics of the high-frequency transformer, this method determines the losses of the high-frequency transformer using the superposition principle. According to the superposition principle, in a circuit, the effect of one power supply can be equivalent to the combined effect of multiple different power supplies.

[0042] The topology of a high-frequency AC-DC matrix converter is as follows: Figure 1 As shown. Figure 1As shown, the high-frequency AC-DC matrix converter may include: a three-phase AC power supply 110, a grid-side filter 120, a matrix switching circuit 131, a high-frequency transformer 132, a full-bridge circuit 133, a DC-side filter 140, and a battery 150. The three-phase AC power supply 110, the grid-side filter 120, and the matrix switching circuit 131 constitute the front-end circuit of the matrix converter, and its output voltage can be simply referred to as the front-end voltage. The full-bridge circuit 133, the DC-side filter 140, and the battery 150 constitute the rear-end circuit of the matrix converter, and its input voltage can be simply referred to as the rear-end voltage. For ease of description, the front-end voltage of the matrix converter is denoted as u. P The voltage of the subsequent stage is expressed as u. s . Figure 2 It shows Figure 1 The diagram shows the equivalent circuit of a high-frequency AC-DC matrix converter. The inductor in this equivalent circuit is the leakage inductance of a high-frequency transformer. Figure 2 As shown, the voltage u of the later stage of the matrix converter can be... s Reconverted to the preceding circuit, we get nu s , where n represents the transformation ratio of the high-frequency transformer, that is, the turns ratio of the primary and secondary coils of the high-frequency transformer. This equivalent circuit can be used to simplify the calculation of losses in a high-frequency transformer.

[0043] Figure 3 A schematic flowchart of a method for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter according to an embodiment of the present invention is shown. Figure 3 As shown, the method includes the following steps.

[0044] Step S310: Based on the modulation strategy of the matrix converter, determine the first power line voltage u, which has the positive polarity and the largest amplitude, in each sector of the AC power supply voltage variation diagram of the matrix converter. max The second power supply line voltage u is positive in polarity and has the second largest amplitude. med And the third power supply line voltage with positive polarity and minimum amplitude.

[0045] Figure 4 It shows Figure 1 The diagram shows the voltage variation sector of the AC power supply for a high-frequency AC-DC matrix converter. Specifically, the voltage variation of the three-phase AC power supply of the matrix converter within one cycle can be divided into 12 sectors, with the peak line voltage being ±U. Lm Since the preceding 3×2 switching matrix circuit selects a line voltage or zero voltage from the power grid to apply to the high-frequency transformer, from the perspective of improving voltage utilization, a line voltage with the highest possible amplitude is selected. Here, the two line voltages with the largest and second largest amplitudes are combined. To distinguish the relative magnitudes of the line voltages, let u... ab uac u bc u ba u ca u cb Based on the six line voltages, the line voltages with the positive polarity, the largest amplitude, and the second largest amplitude can be used to divide each power frequency cycle into 12 sectors as shown in the figure, thereby ensuring that the relative magnitude of the line voltage amplitude remains unchanged in each sector.

[0046] As can be seen from the diagram, within each sector, the maximum and second-largest line voltages are uniquely determined. Define u max u med They represent u respectively ab u ac u bc u ba u ca u cb In the middle, the polarity is positive, and the line voltages with the largest and second largest amplitudes are the line voltages.

[0047] Taking the first sector as an example, the polarity of the line voltage of the AC voltage source in the first sector is positive, and the line voltage with the largest amplitude is u. ac For ease of description, we will refer to this u from now on. ac This represents the maximum power line voltage in the first sector. That is, in the first sector, the first power line voltage u... max Equal to the maximum power line voltage u ac .

[0048]

[0049] In the first sector, the polarity of the line voltage of the AC voltage source is positive, and the second largest amplitude of the line voltage of the AC voltage source is u. ab The u was later referred to as ab This is the second largest power line voltage in the first sector. That is, in the first sector, the second power line voltage u... med Equal to the second largest power supply line voltage u ab The polarity of the line voltage of an AC voltage source is positive, and the line voltage with the smallest amplitude is u. bc The u was later referred to as bc This is the minimum power line voltage in the first sector. That is, in the first sector, the third power line voltage u... min Equal to the maximum power line voltage u bc .

[0050] The waveform of the AC power supply is a sine wave; in other words, the output voltage of the three-phase power supply varies with time. The positive half-cycle of the waveform is divided into three intervals from largest to smallest, based on the intersection of the two line voltage waveforms. The frequency of the three-phase power supply can be 50Hz, which is significantly lower than the typical operating frequency of matrix converters (tens of kHz or even higher). Therefore, the output voltage of the three-phase power supply can be considered constant within each control cycle. For example, in the control cycle from time t1 to t1+Ts in the diagram, the voltage u in the power supply can be considered constant. max u med u min It remains unchanged. From time t2 to the end of the control period (t2+Ts), u... max u med u min The value is less than the value of u starting at time t1. max u med u min The value.

[0051] Similarly, the first power line voltage, the second power line voltage, and the third power line voltage can be determined separately in other sectors, which will not be elaborated here for the sake of simplicity.

[0052] Step S320, based on the first power line voltage u max Second power line voltage u med Third power line voltage u min Given the leakage inductance L of the high-frequency transformer, the transformation ratio of the high-frequency transformer, the voltage of the later stage of the matrix converter, and the pulse width of the maximum amplitude voltage in the preceding stage of the matrix converter, calculate the primary and secondary currents of the high-frequency transformer.

[0053] Due to the characteristics of the modulation strategy of the matrix converter, the current of the high-frequency transformer has the characteristics of high frequency, time-varying amplitude, and irregularity. Figure 5 The preceding voltage u according to an embodiment of this application is shown. p The voltage of the subsequent stage u s and the inductor current i in the leakage inductance L A waveform diagram. (For example...) Figure 5 As shown, u p The waveform is not a standard square wave, making it difficult to obtain the non-sinusoidal periodic function corresponding to the current, and thus impossible to directly analyze the harmonic current through Fourier decomposition. Therefore, in the embodiments of this application, based on the superposition principle, the primary and secondary currents of the high-frequency transformer are determined using the voltage across the leakage inductance of the high-frequency transformer.

[0054] According to the modulation strategy of the matrix converter, in any sector, the preceding voltage u p All can be determined by the first power line voltage u max Second power line voltage u med express.

[0055] Specifically, in a control cycle, u p This can be expressed using the following formula:

[0056]

[0057] Where d1 represents u p The pulse width of the maximum line voltage with medium amplitude, such as Figure 5 As shown.

[0058] Based on the symmetry of the three-phase AC voltage source, the preceding voltage u can be... p and subsequent voltage u s It is equivalent to the superposition of different square wave voltages. Figure 6 The preceding voltage u according to an embodiment of the present invention is shown. p Its superposition is equivalent to the preceding voltage u. p The signal and the subsequent voltage u s The superposition of these voltages is equivalent to the subsequent voltage u. s A schematic diagram of the signal. (e.g.) Figure 6 As shown, the front-end voltage u p It can be divided into three square wave voltage signals u p1 u p2 u p3 , where u p1 The voltage amplitude is 0.5u. max u p2 The voltage amplitude is 0.5u. med u p3 The voltage amplitude is 0.5u. min Among them, u min This indicates the voltage of the third power supply line. p3 with u p1 u p2 With a phase difference of 0.5-d1, three voltage signals u p1 u p2 u p3 Superposition can fit u p u s It can be divided into two square wave voltage signals u with the same phase. s1 and u s2 , where u s1 The voltage amplitude is 0.5u. s u s2 The voltage amplitude is 0.5u. s Expressed as a formula

[0059]

[0060]

[0061] Refer again Figure 2 The equivalent circuit diagram shows that the direction and magnitude of power flow can be adjusted by regulating the phase difference between the voltages on both sides of the leakage inductor. The preceding voltage u... p The voltage of the subsequent stage u s The quantitative relationship between the inductance and the equivalent inductance is as follows:

[0062]

[0063] i L Let L represent the winding harmonic current of the inductor, and t represent time. Therefore, based on the equivalent inductance L and the preceding voltage u... p and subsequent voltage u s The equivalent current i can then be calculated. L This refers to the winding harmonic current.

[0064] According to the superposition theorem, the voltage acting on the leakage inductance L is u. p -nu s , where u p It can be regarded as u p1 u p2 u p3 The result is obtained by superposition, u s It can be regarded as u s1 and u s2 The results are obtained by superposition. Therefore, the primary and secondary currents of a high-frequency transformer can be regarded as the superposition of the inductor currents when five voltage sources act independently on the inductor L. Figure 7 It shows Figure 1 The diagram shown is the equivalent circuit diagram of the disassembled high-frequency AC-DC matrix converter. In this equivalent circuit diagram, u... p Represented as u p1 u p2 u p3 At the same time, u s Represented as u s1 and u s2 If we disregard the magnetizing current in the inductor, we can assume that the secondary current of a high-frequency transformer is equal to n times the primary current.

[0065] Based on formula (2), the first power line voltage u can be determined. max Second power line voltage u med The pulse width d1 determines the preceding voltage u. p Furthermore, based on the above equivalent results and formula (3), the preceding voltage u can be used... p The voltage of the subsequent stage u s Given the leakage inductance L and the transformation ratio n of the high-frequency transformer, calculate the primary current of the high-frequency transformer. The secondary current can then be determined based on the primary current and the transformation ratio.

[0066] Step S330: Calculate the AC winding coefficient F of the high-frequency transformer based on the winding parameters of the high-frequency transformer. r .

[0067] The high-frequency transformer in this application embodiment can use Litz wire. As the operating frequency of a high-frequency transformer increases, the winding conductors experience skin effect and proximity effect, leading to increased winding losses and consequently causing a series of problems such as increased internal temperature of magnetic components and difficulty in heat dissipation. Litz wire, composed of multiple strands of fine wire twisted together, exhibits significantly less skin effect and proximity effect at high frequencies than other wires, making it more widely used in practical engineering. Of course, for high-frequency transformers that do not use Litz wire, the winding can be considered to use a single strand of Litz wire. The winding parameters of the transformer may include the Litz wire fill factor β, the Litz wire resistivity ρ, the number of Litz wire strands N0, and the diameter d0 of the round conductor, etc.

[0068] Figure 8A A simplified schematic diagram of a high-frequency transformer according to an embodiment of the present invention is shown, which includes a transformer core 132A and a transformer winding 132B.

[0069] Figure 9 A schematic cross-sectional view of the Litz line according to an embodiment of the present invention is shown. Figure 9 As shown, the magnetic field strength at a certain point inside the Litz wire winding consists of two parts: one is the magnetic field strength H generated by the thin wires wound inside the Litz wire. int H int It includes two components, x and z, and the magnetic field strength H generated by other windings. ext H ext It follows a one-dimensional distribution along the z-axis.

[0070] Therefore, the magnetic field strength at a certain point within the winding of a high-frequency transformer is shown in the following formula.

[0071] H = H ext +H int

[0072] =(H int cosθ+H ext )e z -H int sinθe x (6)

[0073] Among them, e x e z Let represent the unit vectors along the x and z axes, respectively, and θ represent the angle between the line connecting the point to the origin and the x-axis.

[0074] Figure 8BA cross-sectional view of a Litz wire winding according to an embodiment of the present invention is shown, where m represents the number of layers of Litz wire and n represents the number of turns per layer of Litz wire. The H value of a point on the k-th layer of the transformer winding (let its horizontal distance from the leftmost point of the Litz wire be denoted as Δx) is also shown. ext The value of can be shown in the following formula.

[0075]

[0076] Where I represents the current amplitude, d lizi h represents the diameter of the Lids line. w This indicates the height of winding 132B.

[0077] Express Δx in polar coordinates as Δx = r lizi +rcosθ represents the expression, which gives the following formula:

[0078]

[0079] Where, r lizi Let r represent the radius of the Litz wire, and r represent the radius of the k-th winding.

[0080] like Figure 9 As shown, H int As shown in the following formula:

[0081]

[0082] Therefore, the total magnetic field strength H at a certain point of the k-th layer winding is:

[0083]

[0084] By using the method of electric field energy integration, the power loss per unit length of the Litz wire in the k-th layer and t-th turn can be obtained:

[0085]

[0086] Where β represents the fill factor of the Litz wire, ρ represents the resistivity of the Litz wire, N0 represents the number of strands of the Litz wire, and d0 represents the diameter of the round conductor.

[0087] Based on the characteristic frequency f of the matrix transformer s The skin depth δ can be calculated using the material of the Litz line.

[0088]

[0089] Where μ represents the permeability of the Litz line.

[0090]

[0091]

[0092]

[0093] Where ber and bei represent different Bessel functions of order 0, ber2 represents a Bessel function of order 2, and ber' and bei' represent the derivatives of the corresponding Bessel functions.

[0094] By summing up the power losses of a winding with m layers and n turns of Litz wire, the power loss per unit length of the Litz wire winding in a high-frequency transformer can be obtained.

[0095]

[0096] Based on the relationship between power and current, the expression for AC resistance can be obtained as follows:

[0097]

[0098] Therefore, the AC resistivity of the Litz wire winding can be obtained as:

[0099]

[0100] The expression for the DC resistance of a Litz wire winding:

[0101]

[0102] Step S340, based on the primary current, secondary current and AC winding coefficient F r Calculate the winding losses of a high-frequency transformer.

[0103] It is understandable that the following formula holds true for matrix transformers:

[0104]

[0105]

[0106] DC resistance R of the winding dc It can be easily measured, or calculated based on the type and length of the Litz wire used, as shown in formula (17). rms,k This represents the effective value of the kth harmonic of the current.

[0107] According to the AC resistivity expression (16), the AC resistivity under each order of harmonic current can be obtained, and thus the winding loss under a single order harmonic can be calculated separately. Using the superposition principle, the winding losses corresponding to each order of current harmonics are summed to obtain the winding loss as shown in the equation:

[0108]

[0109] Among them, I p,k Is,k These represent the k-th harmonic peak values ​​of the primary and secondary currents, respectively, with the peak current being the effective value of the current. times.

[0110] Step S350: Calculate the core loss of the high-frequency transformer based on the preceding voltage, the number of turns in the high-frequency transformer winding, and the core parameters.

[0111] Besides the winding losses calculated in step S340, core losses are also a significant loss in high-frequency transformers. Core losses are the energy consumed by ferromagnetic materials in a high-frequency transformer during repeated magnetization due to hysteresis. Hysteresis refers to the phenomenon where the magnetization intensity lags behind the magnetic field strength when the magnetic state of a ferromagnetic material changes; its magnetic flux density and magnetic field strength exhibit a hysteresis loop relationship. After one cycle, the hysteresis loss per unit volume of the core is proportional to the area of ​​the hysteresis loop. This energy is converted into heat, causing the equipment to heat up and reducing efficiency; it is a component of iron losses in electrical equipment.

[0112] In this step S350, the core loss of the high-frequency transformer can be calculated based on the preceding voltage of the matrix converter, the number of turns of the high-frequency transformer winding, and the core parameters.

[0113] Step S360: Add the winding loss and the core loss to obtain the loss of the high-frequency transformer. According to one embodiment of the present invention, the sum of the winding loss and the core loss is determined as the total loss of the high-frequency transformer.

[0114] In the above technical solution, the losses of the high-frequency transformer in the high-frequency chain AC-DC matrix converter are determined based on the superposition principle. First, the first, second, and third power line voltages, which are superimposed and equivalent to the preceding voltages of the matrix converter, are determined. Then, based on these power line voltages, the primary circuit and secondary current of the high-frequency transformer are determined, and the winding losses of the high-frequency transformer are calculated. The core loss of the high-frequency transformer is calculated based on the preceding voltages of the matrix converter, the number of turns in the high-frequency transformer windings, and the core parameters. Finally, based on the winding losses and core losses, the total loss of the high-frequency transformer is obtained. This solution avoids the negative impact of the non-sinusoidal characteristics of voltage and current on the calculation of high-frequency transformer losses during actual operation, resulting in more accurate loss determination.

[0115] The most significant component of the primary and secondary currents in a high-frequency transformer is its winding harmonic current. According to one embodiment of the present invention, this winding harmonic current can be considered as both the primary and secondary currents of the high-frequency transformer. In this case, the secondary current is equal to n times the primary current.

[0116] For example, the above step S320, which calculates the primary and secondary currents of the high-frequency transformer, may include step S323: calculating the primary winding current and secondary winding current of the high-frequency transformer based on the first power line voltage, the second power line voltage, the third power line voltage, the leakage inductance of the high-frequency transformer, the transformation ratio of the high-frequency transformer, the voltage of the subsequent stage of the matrix converter, and the pulse width of the voltage with the largest amplitude in the preceding stage of the matrix converter.

[0117] For example, calculating the primary winding current and secondary winding current of a high-frequency transformer includes: calculating the primary winding current i, excluding the excitation current's kth harmonic, according to the following formula. L，k Amplitude:

[0118]

[0119] Where L represents the leakage inductance of the high-frequency transformer, k represents the harmonic order, and n represents the transformation ratio of the high-frequency transformer. u represents the phase difference between the preceding and following voltage stages. max Indicates the first power supply line voltage, u med Indicates the second power supply line voltage, u min d1 represents the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and f represents the voltage of the third power supply line. s This represents the characteristic frequency of the matrix transformer.

[0120] As mentioned earlier, the effect of the preceding voltage on the high-frequency transformer in the matrix converter can be equivalent to multiple voltage u. p1 u p2 u p3 The function is to utilize the first power line voltage u. max Second power line voltage u med Third power line voltage u min The pulse width d1 of the maximum amplitude voltage in the preceding stage voltage of the matrix converter can determine the square wave voltage u. p1 u p2 u p3 The expression with time as the variable. The voltage amplitude can be multiplied by an auxiliary function f(t). f(t) is a square wave signal with a duty cycle of 0.5 and an amplitude of 1 / 2. Figure 10 A schematic diagram of a square wave of function f(t) is shown. The current expression obtained after this square wave acts on the inductance of a high-frequency transformer can be obtained by Fourier transform to obtain the expression for the harmonic current. This simplifies the calculation. Furthermore, u can be... p1 Using u max f(t) represents, similarly, u p2 and u p3 Using u med f(t) and u minf(t) represents this. Therefore, we can obtain:

[0121]

[0122] Based on the subsequent voltage u of the matrix converter s The turns ratio n of the high-frequency transformer and the preceding voltage u p Phase difference with the subsequent voltage It can be obtained

[0123]

[0124] As mentioned earlier, the subsequent voltage u can be... s Split into u s1 and u s2 This facilitates subsequent calculations.

[0125] In calculating the winding current i L When (t), it can be regarded as the superposition of the inductor current when five voltage sources act independently on the inductor L, such as Figure 6 As shown.

[0126] Integrating equation (5) yields the winding current i. L The expression for (t):

[0127]

[0128] Among them, i L1 (t), i L2 (t), i L3 (t), i L4 (t) and i L5 (t) respectively represent the expression by u p1 u p2 u p3 u s1 and u s2 The current generated by each. s This represents the characteristic frequency of the matrix transformer. Exemplarily, and not limitingly, f s It can be 33kHz.

[0129] In formula (21), each term contains a function g(t). Figure 11 A schematic diagram of a function g(t) according to an embodiment of the present invention is shown. g(t) can be expressed by the following formula:

[0130]

[0131] Therefore, the winding harmonic current i L The expression for (t) can be:

[0132]

[0133] Similar to f(t) above, g(t) is also set to simplify calculations.

[0134] For the winding harmonic current i shown in formula (23) L Performing a Fourier transform on (t) yields the following expression for the winding current.

[0135]

[0136] Where the Fourier coefficient c k Expressed using the following formula:

[0137]

[0138] Where k = 1, 3, 5...

[0139] At this point, the winding current i is calculated. L The amplitude is:

[0140]

[0141] Therefore, the winding harmonic currents of the primary and secondary sides are respectively

[0142] Therefore, based on the first power line voltage u max Second power line voltage u med Third power line voltage u min The pulse width d1 of the maximum amplitude voltage in the front-stage voltage of the matrix converter; the voltage u of the rear-stage voltage of the matrix converter. s Given the transformer's turns ratio n and leakage inductance L, calculate the amplitude of the harmonic currents in the primary and secondary windings.

[0143] The above method of calculating the harmonic currents of the primary and secondary windings is more accurate, thus ensuring a more accurate calculation of the total loss of the high-frequency transformer.

[0144] For example, the above step S320 for calculating the primary and secondary currents of the high-frequency transformer may include not only step S323, but also the following steps S321, S322 and S324.

[0145] In step S321, the primary-side magnetizing current of the high-frequency transformer is calculated based on the magnetizing inductance of the high-frequency transformer, the first power supply line voltage, the second power supply line voltage, the third power supply line voltage, and the pulse width of the maximum amplitude voltage in the preceding stage voltage. In step S322, the primary-side magnetizing current of the high-frequency transformer is calculated based on the magnetizing inductance of the high-frequency transformer and the voltage u of the subsequent stage of the matrix converter. s Calculate the equivalent secondary excitation current of the high-frequency transformer based on the transformer ratio n.

[0146] The magnetizing inductance is the inductance of the transformer's front winding. Since the magnetic flux density of the core gradually increases upon energization, this process can be considered the transformer's excitation process. Considering this excitation process... Figure 1 The topology shown can be transformed into Figure 12 The equivalent circuit is shown. Based on this equivalent circuit and the voltage and current characteristics of the inductor, similar to the calculation process of the winding harmonic current above, the magnetizing inductance L of the high-frequency transformer can be used as a reference. m And the characteristic frequency of the matrix converter, calculate the primary excitation current i. mp and secondary excitation current i' ms .

[0147] In step S324, refer to Figure 12 The primary and secondary harmonic currents of a high-frequency transformer can be calculated based on the primary excitation current, the equivalent secondary excitation current, and the winding harmonic currents.

[0148] i p =i mp +i L

[0149] i′ s =i L -i′ ms

[0150] The above technical solution takes into account the magnetizing inductance of the high-frequency transformer, thus the calculated loss of the high-frequency transformer is more accurate and the error is smaller.

[0151] For example, similar to step S323 which calculates the primary winding harmonic current of the high-frequency transformer, step S321 which calculates the primary excitation current of the high-frequency transformer may include: calculating c according to the following formula mp，k and c mp，k The modulus is determined to be the primary excitation current i of the kth harmonic. mp，k Amplitude:

[0152]

[0153] like Figure 12 As shown, considering the excitation branch, the primary current can be expressed as the superposition of the current acting on the leakage inductance of the high-frequency transformer and the current in the excitation branch. The preceding voltage u p Directly applied to the magnetizing inductor L m On top, the primary side excitation current i is generated. mp，k .

[0154] In the above technical solution, the above formula is used to determine the first power supply line voltage u. max Second power line voltage umed Third power line voltage u min The pulse width d1 of the maximum amplitude voltage in the preceding stage voltage of the matrix converter; the characteristic frequency f of the matrix converter. s and the magnetizing inductance L of the high-frequency transformer m Calculate the primary excitation current i mp，k The amplitude of the total harmonic current can be further improved, which in turn improves the accuracy of the calculation of the loss of the high-frequency transformer.

[0155] For example, similar to step S323 which calculates the harmonic current of the secondary winding of the high-frequency transformer, step S322 calculates the equivalent secondary excitation current of the high-frequency transformer, including calculating c' according to the following formula. ms，k and c' ms，k The modulus is determined as the equivalent secondary excitation current i' of the kth harmonic. ms，k Amplitude:

[0156]

[0157] Continue to refer to Figure 12 The secondary current can be expressed as the superposition of the current acting on the leakage inductance of the high-frequency transformer and the current in the excitation branch. The voltage of the subsequent stage is referred back to the preceding stage. s Directly applied to the magnetizing inductor L m On top, a secondary excitation current i' is generated. ms，k .

[0158] In the above technical solution, the above formula is used to determine the voltage u of the subsequent stage of the matrix converter. s The transformation ratio n of the high-frequency transformer, and the phase difference between the preceding voltage and the following voltage of the matrix converter. The characteristic frequency f of the matrix transformer s and the magnetizing inductance L of the high-frequency transformer m Calculate the equivalent secondary excitation current i' ms，k The amplitude of the total harmonic current is increased, thereby improving the calculation accuracy of the total harmonic current and, consequently, the calculation accuracy of the loss of the high-frequency transformer.

[0159] For example, step S324 includes calculating the primary and secondary currents of each harmonic of the high-frequency transformer according to the following formula:

[0160]

[0161] For example, step S350, which calculates the core loss of the high-frequency transformer, includes steps S351 and S352.

[0162] In step S351, based on the number of turns N of the high-frequency transformer winding, the core cross-sectional area S, the first power supply line voltage, the second power supply line voltage, the pulse width d1 of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and the characteristic frequency f of the matrix converter... s Calculate the peak magnetic flux density B of the high-frequency transformer. m .

[0163] According to the law of electromagnetic induction:

[0164]

[0165] Therefore, based on the voltage u of the high-frequency transformer front stage p Calculate the rate of change of magnetic flux density B. (U...) p Disassemble into u max and u med The expression for the rate of change of magnetic flux density B can be obtained as follows:

[0166]

[0167] Where T s This represents the control period, which is the characteristic frequency f of the matrix converter. s The reciprocal of.

[0168] Figure 13 A schematic diagram illustrating the relationship between the front-stage voltage and the rear-stage voltage of a high-frequency transformer according to an embodiment of the present invention and the magnetic induction intensity is shown. Figure 13 As shown, the magnetic flux density is at -B max B med B max -B med The cycle repeats. Based on its meaning, ΔB is:

[0169]

[0170] The voltage excitation is symmetrical, and the peak magnetic flux density can be calculated based on ΔB.

[0171] For example, calculating the peak magnetic flux density of the primary side of a high-frequency transformer includes: calculating the peak magnetic flux density according to the following formula:

[0172]

[0173] The above process calculates the peak magnetic flux density on the primary side of a high-frequency transformer. Similarly, the peak magnetic flux density on the secondary side of a high-frequency transformer can be calculated in a similar manner.

[0174]

[0175]

[0176] Among them, u s This represents the voltage of the subsequent stage of the matrix converter. This indicates the phase difference between the preceding voltage and the following voltage.

[0177] Thus, the secondary voltage u of the high-frequency transformer is obtained. s The corresponding peak magnetic flux density.

[0178] In step S352, the peak magnetic induction intensity B can be used as a reference. m The loss coefficient of the magnetic core material of the high-frequency transformer is used to calculate its core loss.

[0179] For example, the Steinmetz Equation (SE) can be used for calculation, i.e., the SE formula:

[0180]

[0181] Among them, P v The SE formula represents the core loss per unit volume. K, α, and β represent loss coefficients, which are constants and can be obtained by fitting data from core material datasheets. While the SE formula is simple and convenient, suitable for engineering applications, it is more applicable to calculating the core loss of high-frequency transformers under standard sinusoidal excitation. However, its accuracy is not high for calculating the core loss under non-sinusoidal excitation.

[0182] In the above technical solution, the peak magnetic flux density of the high-frequency transformer is first calculated, and then the core loss is calculated based on this peak magnetic flux density. The obtained core loss is more accurate, thus ensuring the accuracy of the final total loss.

[0183] For example, step S352 calculates the core loss based on the peak magnetic induction intensity and the loss coefficient of the core material of the high-frequency transformer, including using the modified Steinmetz equation MSE, the generalized Steinmetz equation IGSE, and / or the waveform similarity coefficient Steinmetz equation WcSE to calculate the core loss of the high-frequency transformer.

[0184] Specifically, the primary core loss of a high-frequency transformer can be calculated using the following formula.

[0185] Improved Steinmetz equation:

[0186]

[0187] Generalized Steinmetz equation:

[0188]

[0189]

[0190] Steinmetz equation for waveform similarity coefficient:

[0191]

[0192] The core loss on the primary side of a high-frequency transformer can be calculated using one or more of the formulas mentioned above.

[0193] The secondary core loss of a high-frequency transformer can be calculated using the following formula.

[0194] Improved Steinmetz equation:

[0195]

[0196] Generalized Steinmetz equation:

[0197]

[0198] Steinmetz equation for waveform similarity coefficient:

[0199]

[0200] The core loss on the secondary side of the high-frequency transformer can be calculated using one or more of the above formulas. The total core loss of the high-frequency transformer can be obtained by adding the core loss on the primary side to the core loss on the secondary side.

[0201] Using the above formula can significantly improve the accuracy of core loss calculation. Furthermore, the errors of the three formulas will vary for different matrix converters, so the most suitable formula can be selected for calculation as needed.

[0202] According to another aspect of this application, an electronic device is also provided, including a processor and a memory, wherein the memory stores computer program instructions, which are executed by the processor to perform the above-described method for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter.

[0203] According to another aspect of this application, a storage medium is also provided, on which program instructions and parameters required by the program are stored. When the program instructions are run by a processor, they are used to execute the corresponding steps of the method for determining the loss of a high-frequency transformer in a high-frequency chain AC-DC matrix converter according to the embodiments of this application. The storage medium may include, for example, a storage component, a hard disk, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable read-only memory (CD-ROM), a USB memory, or any combination of the above storage media.

[0204] Those skilled in the art can understand the specific implementation scheme and beneficial effects of the above-mentioned program instructions and storage medium by reading the relevant description of the method for determining the loss of high-frequency transformers in high-frequency chain AC-DC matrix converters. For the sake of brevity, they will not be described in detail here.

[0205] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0206] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0207] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus so disclosed can be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0208] The various component embodiments of this application can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. This application can also be implemented as an apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such an implementation of this application can be stored on a computer-readable medium, or can take the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

Claims

1. A method for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter, characterized in that, include: According to the modulation strategy of the matrix converter, the first power line voltage with positive polarity and the largest amplitude, the second power line voltage with positive polarity and the second largest amplitude, and the third power line voltage with positive polarity and the smallest amplitude are determined in each sector of the voltage change diagram of the AC power supply of the matrix converter. The primary and secondary currents of the high-frequency transformer are calculated based on the first power line voltage, the second power line voltage, the third power line voltage, the leakage inductance of the high-frequency transformer, the transformation ratio of the high-frequency transformer, the voltage of the later stage of the matrix converter, and the pulse width of the maximum amplitude voltage in the voltage of the earlier stage of the matrix converter. Calculate the AC winding coefficient of the high-frequency transformer based on the winding parameters of the high-frequency transformer; The winding losses of the high-frequency transformer are calculated based on the primary current, the secondary current, and the AC winding coefficient. Calculate the core loss of the high-frequency transformer based on the preceding and following voltages, the number of turns in the winding of the high-frequency transformer, and the core parameters. as well as The winding loss and the core loss are added together to obtain the loss of the high-frequency transformer; The calculation of the primary and secondary currents of the high-frequency transformer includes: The primary excitation current of the high-frequency transformer is calculated based on the excitation inductance of the high-frequency transformer, the first power line voltage, the second power line voltage, the third power line voltage, and the pulse width of the maximum amplitude voltage in the preceding stage voltage. The equivalent secondary excitation current of the high-frequency transformer is calculated based on the magnetizing inductance of the high-frequency transformer, the voltage of the subsequent stage of the matrix converter, and the transformation ratio of the high-frequency transformer. Based on the first power line voltage, the second power line voltage, the third power line voltage, the leakage inductance of the high-frequency transformer, the transformation ratio of the high-frequency transformer, the voltage of the subsequent stage of the matrix converter, and the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, calculate the primary winding harmonic current and the secondary winding harmonic current of the high-frequency transformer. The primary current and the secondary current of the high-frequency transformer are calculated based on the primary excitation current, the equivalent secondary excitation current, the primary winding harmonic current, and the secondary winding harmonic current.

2. The method as described in claim 1, characterized in that, The calculation of the primary winding current of the high-frequency transformer includes: calculating the primary winding harmonic current i of the kth harmonic according to the following formula. L，k Amplitude: Where L represents the leakage inductance of the high-frequency transformer, k represents the harmonic order, and n represents the transformation ratio of the high-frequency transformer. u represents the phase difference between the preceding and following voltage stages. max Indicates the first power supply line voltage, u med Indicates the second power supply line voltage, u min d1 represents the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and f represents the voltage of the third power supply line. s The characteristic frequency u of the matrix transformer is represented by u. s This represents the voltage of the subsequent stage of the matrix converter.

3. The method as described in claim 1 or 2, characterized in that, The calculation of the primary excitation current of the high-frequency transformer includes: calculating c according to the following formula. mp，k and c mp，k The modulus is determined to be the primary excitation current i of the kth harmonic. mp，k Amplitude: Among them, L m This represents the magnetizing inductance of a high-frequency transformer, k represents the harmonic order, and u... max Indicates the first power supply line voltage, u med Indicates the second power supply line voltage, u min d1 represents the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and f represents the voltage of the third power supply line. s The characteristic frequency of the matrix converter is represented by j0, and j0 indicates that the imaginary impedance angle is 0 in the initial state.

4. The method as described in claim 1 or 2, characterized in that, The calculation of the equivalent secondary excitation current of the high-frequency transformer includes calculating c' according to the following formula. ms，k and c' ms，k The modulus is determined as the equivalent secondary excitation current i' of the kth harmonic. ms，k amplitude, ， Among them, L m This represents the magnetizing inductance of the high-frequency transformer, k represents the harmonic order, and n represents the transformer's turns ratio. f represents the phase difference between the preceding voltage and the following voltage of the matrix converter. s The characteristic frequency u of the matrix transformer is represented by u. s This represents the voltage of the subsequent stage of the matrix converter.

5. The method according to any one of claims 1 to 2, characterized in that, The calculation of the core loss of the high-frequency transformer includes: The peak magnetic flux density of the high-frequency transformer is calculated based on the number of winding turns, core cross-sectional area, first power line voltage, second power line voltage, pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and characteristic frequency of the matrix converter. The core loss is calculated based on the peak magnetic induction intensity and the loss coefficient of the core material of the high-frequency transformer.

6. The method as described in claim 5, characterized in that, The calculation of the core loss based on the peak magnetic induction intensity and the loss coefficient of the core material of the high-frequency transformer includes: The core loss is calculated using the modified Steinmetz equation, the generalized Steinmetz equation, and / or the waveform similarity coefficient Steinmetz equation, based on the peak magnetic induction intensity and the loss coefficient of the core material of the high-frequency transformer.

7. The method as described in claim 5, characterized in that, The calculation of the peak magnetic flux density of the high-frequency transformer includes: The peak magnetic flux density of the primary side of the high-frequency transformer is calculated using the following formula: ， The peak magnetic flux density of the secondary side of the high-frequency transformer is calculated using the following formula: ， Among them, B m，p B represents the peak magnetic flux density of the primary side. m，s T represents the peak magnetic flux density of the secondary side. s Indicates the control period, N represents the number of turns in the high-frequency transformer winding, S represents the core cross-sectional area, and u max Indicates the first power supply line voltage, u med d1 represents the pulse width of the maximum amplitude voltage in the preceding stage voltage of the matrix converter, and u represents the voltage of the second power supply line. s This represents the voltage of the subsequent stage of the matrix converter. This indicates the phase difference between the preceding voltage and the following voltage.

8. An electronic device comprising a processor and a memory, characterized in that, The memory stores computer program instructions, which, when executed by the processor, are used to perform the method for determining the losses of a high-frequency transformer in a high-frequency chain AC-DC matrix converter as described in any one of claims 1 to 7.

9. A storage medium on which program instructions are stored, characterized in that, The program instructions, when executed, are used to perform the method for determining the losses of the high-frequency transformer in a high-frequency chain AC-DC matrix converter as described in any one of claims 1 to 7.

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