A method for analyzing magnetic bias of a full-bridge converter

Abstract

The application discloses a full-bridge converter magnetic bias analysis method, comprising the following steps: converting the voltage of the input side capacitor of the full-bridge converter into a pulse voltage through the switching network of the full-bridge converter; injecting the pulse voltage into the resonant inductance of the full-bridge converter; measuring the voltage signal and the current signal of the resonant inductance; and analyzing the measured voltage signal and current signal to realize the direct current magnetic bias analysis of the full-bridge converter. The application injects the alternating voltage with positive and negative conversion into the resonant inductance to obtain the voltage and current waveforms, analyzes the voltage deviation of the positive and negative half cycles, obtains the reason for the magnetic bias of the full-bridge direct current converter, provides the basis for the design and selection of the resonant inductance, and effectively improves the reliability of the system.

Description

Technical Field

[0001] This invention relates to the field of full-bridge DC-DC converter technology, and more specifically to a method for bias magnetization analysis of a full-bridge converter. Background Technology

[0002] In the field of power electronic converters, high efficiency and high reliability are the goals that system control has always pursued. In full-bridge converters, the addition of a resonant inductor enables soft-switching operation of the full-bridge switches, greatly improving the system's operating efficiency. However, the design of the resonant inductor and unavoidable system drive and control errors will lead to DC bias in the converter, thus affecting the reliability of the entire system. Therefore, the analysis method of DC bias in full-bridge converters plays a crucial role in suppressing bias and can greatly improve the reliability of the system.

[0003] There are many methods for suppressing magnetization in existing full-bridge converters, mainly including the addition of DC blocking capacitors and peak current control correction. However, in system applications, the DC blocking capacitors need to withstand voltage changes between positive and negative for extended periods, leading to a shortened lifespan and becoming a major factor limiting the overall lifespan of the full-bridge converter. Peak current control, due to its bandwidth limitations, often has limited correction capabilities, and its response speed also limits the effectiveness of protection against magnetization faults.

[0004] Existing technologies lack analysis of DC bias in full-bridge converters, making it impossible to effectively detect DC bias and affecting the design of resonant inductors in full-bridge converters. Summary of the Invention

[0005] The purpose of this invention is to provide a method for analyzing the bias magnetism of a full-bridge converter. It aims to address the problem in existing technologies that lack analysis of the DC bias magnetism of full-bridge converters, thus failing to effectively detect the DC bias magnetism and affecting the design of the resonant inductor in the full-bridge converter.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] This invention provides a bias magnetization analysis method for a full-bridge converter, which is applied to the power supply and distribution system of a space station, including:

[0008] Step S1: Convert the voltage of the input capacitor of the full-bridge converter into a pulse voltage through the switching network of the full-bridge converter;

[0009] Step S2: Inject the pulse voltage into the resonant inductor of the full-bridge converter;

[0010] Step S3: Measure the voltage and current signals of the resonant inductor;

[0011] Step S4: analyzing the measured voltage signal and the measured current signal to realize the DC bias analysis of the full-bridge converter.

[0012] Preferably, the measured voltage signal and the measured current signal are analyzed, specifically, the deviation of the voltage signal obtained at the positive half cycle and the negative half cycle of the injected pulse voltage is analyzed.

[0013] Preferably, in step S3, the voltage signal and the current signal of the resonant inductor are measured to obtain the voltage signal and the current signal, and a waveform diagram of the voltage signal is drawn.

[0014] Preferably, the current signal is obtained by an oscilloscope test, and a waveform diagram of the current signal is obtained according to the oscilloscope.

[0015] Preferably, the measured current signal is analyzed, specifically including: according to the inductor magnetic circuit law, analyzing the magnetic field strength of the resonant inductor when the current signal increases.

[0016] Preferably, according to the magnetic induction strength and the magnetic field strength, a magnetization curve of magnetic induction strength-magnetic field strength is drawn to analyze the magnetic permeability and obtain the inductance of the full-bridge converter.

[0017] Preferably, according to the inductance, the primary side voltage of the transformer is analyzed to obtain the deviation of the voltage signal.

[0018] Preferably, when the pulse voltage on the resonant inductor is the positive half cycle, the specific steps of obtaining the voltage signal are as follows:

[0019] Step S4.1: obtaining the difference of the magnetic permeability under two different currents of the full-bridge converter according to the magnetic permeability under the two different currents;

[0020] Step S4.2: obtaining the difference of the inductance under the two different currents according to the difference of the magnetic permeability;

[0021] Step S4.3: obtaining the voltage signal, i.e. the primary side voltage of the transformer of the full-bridge converter, when the pulse voltage is the positive half cycle according to the difference of the inductance.

[0022] Preferably, when the pulse voltage on the resonant inductor is the negative half cycle, the specific steps of obtaining the voltage signal are as follows:

[0023] Step S4.4: obtaining the difference of the magnetic permeability under two different currents of the full-bridge converter according to the magnetic permeability under the two different currents;

[0024] Step S4.5: obtaining the difference of the inductance under the two different currents according to the difference of the magnetic permeability;

[0025] Step S4.6: obtaining the voltage signal, i.e. the voltage of the primary side of the transformer of the full-bridge converter, when the pulse voltage is in the negative half cycle according to the difference of the inductance.

[0026] Preferably, the magnetic bias analysis of the full-bridge converter is realized by analyzing the two voltages of the primary side of the transformer obtained when the pulse voltage is in the positive half cycle and the negative half cycle respectively.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] The present application obtains the voltage current waveform by injecting the AC voltage with positive and negative transformation on the resonant inductance, and obtains the reason of the magnetic bias of the full-bridge DC converter through the analysis and calculation of the voltage deviation of the positive and negative half cycles, thereby providing the basis for the design and selection of the resonant inductance and effectively improving the reliability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the description. Obviously, the drawings in the following description are one embodiment of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings:

[0030] Figure 1 The full-bridge converter circuit diagram provided for an embodiment of the present application;

[0031] Figure 2 The full-bridge converter switching network pulse injection waveform provided for an embodiment of the present application;

[0032] Figure 3 The resonant inductance current waveform of the full-bridge converter provided for an embodiment of the present application;

[0033] Figure 4 The positive half cycle B-H magnetization curve diagram provided for an embodiment of the present application;

[0034] Figure 5 The positive half cycle full-bridge converter equivalent circuit diagram provided for an embodiment of the present application;

[0035] Figure 6 The positive half cycle full-bridge converter magnetic bias reason analysis diagram provided for an embodiment of the present application;

[0036] Figure 7 The negative half cycle B-H magnetization curve diagram provided for an embodiment of the present application. DETAILED DESCRIPTION

[0037] The application will be described in further detail below with reference to the drawings. Figures 1-7 The full-bridge converter bias magnetic analysis method according to the present application will be described in further detail in conjunction with the specific embodiments and the best mode. The advantages and features of the present application will be more apparent from the following description. It should be noted that the drawings are very simplified and all the proportions are not accurate, which are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application. In order to make the purpose, features and advantages of the present application more obvious and easy to understand, please refer to the drawings. It should be noted that the structure, proportion, size and the like shown in the drawings of the present application are only used to cooperate with the content disclosed in the description, so as to be understood and read by those skilled in the art, and are not used to limit the conditions for implementing the present application, and therefore do not have technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, which does not affect the effect and purpose that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0038] In view of the problems that the prior art lacks analysis of DC bias magnetic of a full-bridge converter, cannot effectively detect the DC bias magnetic of the full-bridge converter, and affects the design of the resonant inductor in the full-bridge converter, the present embodiment provides a full-bridge converter bias magnetic analysis method, which comprises the following steps:

[0039] Step S1: converting the voltage of the input side capacitor of the full-bridge converter into a pulse voltage through the switching network of the full-bridge converter.

[0040] Step S2: injecting the pulse voltage into the resonant inductor of the full-bridge converter.

[0041] Step S3: measuring the voltage signal and the current signal of the resonant inductor, obtaining the voltage signal and the current signal, and drawing a waveform graph of the voltage signal.

[0042] The current signal is obtained by oscilloscope testing, and the waveform graph of the current signal is obtained according to the oscilloscope.

[0043] Step S4: analyzing the deviation of the voltage signal obtained during the positive half cycle and the negative half cycle of the injected pulse voltage, so as to realize the DC bias magnetic analysis of the full-bridge converter.

[0044] According to the inductance magnetic circuit law, the magnetic field intensity of the resonant inductor when the current signal increases is analyzed.

[0045] According to the magnetic induction intensity and the magnetic field intensity, a magnetization curve of magnetic induction intensity-magnetic field intensity is drawn, so as to analyze the magnetic permeability and obtain the inductance of the full-bridge converter.

[0046] According to the inductance, the transformer primary voltage is analyzed to obtain the deviation of the voltage signal.

[0047] The specific steps for obtaining the voltage signal when the pulse voltage on the resonant inductance is positive half cycle are:

[0048] Step S4.1: According to the permeability of the full-bridge converter under two different currents, the difference of the permeability under the two different currents is obtained.

[0049] Step S4.2: According to the difference of the permeability, the difference of the inductance under the two different currents is obtained.

[0050] Step S4.3: According to the difference of the inductance, the voltage signal, i.e. the voltage of the transformer primary side of the full-bridge converter, when the pulse voltage is positive half cycle is obtained.

[0051] The specific steps for obtaining the voltage signal when the pulse voltage on the resonant inductance is negative half cycle are:

[0052] Step S4.4: According to the permeability of the full-bridge converter under two different currents, the difference of the permeability under the two different currents is obtained.

[0053] Step S4.5: According to the difference of the permeability, the difference of the inductance under the two different currents is obtained.

[0054] Step S4.6: According to the difference of the inductance, the voltage signal, i.e. the voltage of the transformer primary side of the full-bridge converter, when the pulse voltage is negative half cycle is obtained.

[0055] By analyzing the two transformer primary side voltages obtained respectively in positive half cycle and negative half cycle, the offset analysis of the full-bridge converter is realized.

[0056] In this embodiment, referring to Figure 1 As shown in the figure, the entire full-bridge converter system includes input side capacitor C in , switching network Q1, Q2, Q3 and Q4, resonant inductance L r , transformer T1, rectifier bridge D1, D2, D3 and D4, output side capacitor C0.

[0057] The voltage on the input side capacitor C in is V in , and the switching network converts the direct current voltage V in into pulse voltage v AB through switching tubes Q1, Q2, Q3 and Q4; in the full-bridge converter, the pulse voltage is converted into alternating current through resonant inductance L rThe system achieves soft switching; the transformer ratio is 1:N, achieving electrical isolation between the primary and secondary sides while simultaneously enabling voltage variation; the rectifier bridge processes the AC voltage on the secondary side of the transformer into a DC voltage V0.

[0058] The input DC voltage V is converted through a switching network. in The control is a pulse voltage, which is applied to the resonant inductor L. r Above. By analyzing the resonant inductance L r The voltage and current signals are analyzed to determine the DC bias mechanism of the full-bridge converter.

[0059] Pulse control is applied to the switching network; the voltage and current across the resonant inductor are measured; the measured quantities across the resonant inductor are analyzed to obtain a method for analyzing the magnetic bias caused by the resonant inductor.

[0060] According to the law of magnetic circuits of inductance:

[0061] Hl e =Ni (1)

[0062] Where: H represents the magnetic field strength, l e The value represents the length of the magnetic circuit, N represents the number of inductor turns, and i represents the current flowing through the inductor.

[0063] Inductor turns N and magnetic circuit length l e Both are constants. When the current flowing through the inductor increases, according to the above formula (1), the magnetic field strength H of the inductor increases.

[0064] The magnetic flux density B is obtained from the magnetic field strength H:

[0065] B = μ r μ0H=μH (2)

[0066] In the formula: B represents the magnetic flux density, μ r μ represents relative permeability, μ0 represents free permeability, μ represents permeability, and H represents magnetic field strength.

[0067] Plot the BH magnetization curve, refer to Figure 4 As shown, by Figure 4 It can be seen that as the magnetic field strength H continuously increases, its slope becomes increasingly gentle, that is, μ=B / H will continuously decrease.

[0068] The expression for calculating inductance is:

[0069]

[0070] Among them: A e The cross-sectional area of ​​the magnetic core is represented by N, the number of inductor turns is represented by i, and the current flowing through the inductor is represented by i.

[0071] Number of inductor turns N, magnetic circuit length le and the core cross-sectional area A e are constants, so the inductance L decreases with the decrease of the permeability μ.

[0072] Reference Figure 5 The equivalent circuit of the phase-shift full-bridge converter with the resonant inductor is shown in the figure;

[0073] According to the above figure, the voltage across the transformer is:

[0074] v p = V in -V L (4)

[0075] The voltage across the resonant inductor is:

[0076]

[0077] With the decrease of the inductance L, the voltage drop across the inductor decreases, and the input voltage V in is constant, so the primary voltage of the transformer increases with the decrease of the voltage drop across the inductor.

[0078] During the positive half cycle, assume that the initial current i1 corresponds to a magnetic field strength H1, and the current increases to i2, which corresponds to a magnetic field strength H2. The magnetic induction strengths corresponding to the two magnetic field strengths H1 and H2 are B1 and B2, respectively, and the permeabilities are μ1 and μ2, respectively. Then the expressions for the permeabilities μ 1+ and μ 2+ during the positive half cycle are:

[0079]

[0080] The expression for the difference in permeability Δμ under different currents is:

[0081] Δμ + = μ 1+ - μ 2+ (7)

[0082] The expression for the difference in inductance ΔL + under different currents is:

[0083]

[0084] The expression for the primary voltage of the transformer under different currents is:

[0085]

[0086] In the above formula (9), v p2 is the primary voltage of the transformer when the current is i2, v p1 is the primary voltage of the transformer when the current is i1, and Δvp+ The voltage increment of the primary side of the current transformer is twice.

[0087] At the negative half cycle, the negative intensity is -H2, the two magnetic field intensities are B1 and B2, the corresponding magnetic induction intensity distribution is -B1 and -B2, and the permeabilities are μ 1- and μ 2- The difference in the permeability is different from that corresponding to the positive half cycle current, and the expression of the difference in the permeability Δμ is:

[0088] Δμ _ = μ 1_ - μ 2- (10)

[0089] At different currents, the difference in the inductance ΔL _ is:

[0090]

[0091] At the negative half cycle at different currents, the voltage of the primary side of the transformer is:

[0092]

[0093] In the above formula (12), Δv p- is the voltage increment of the primary side of the transformer at different currents at the negative half cycle.

[0094] In the above formula (9) and the above formula (12), the difference in the voltage of the primary side of the transformer at the positive half cycle and the negative half cycle of the pulse voltage is the direct current bias magnetic field of the full-bridge converter, so that the analysis of the reason for the direct current bias magnetic field of the full-bridge converter is realized.

[0095] In summary, the embodiment adopts a direct current bias magnetic field analysis method, realizes the analysis of the reason for the direct current bias magnetic field of the full-bridge converter, and gives a scheme for suppressing the direct current bias magnetic field, which greatly improves the reliability of the entire full-bridge converter system. The method analyzes the possibility of the bias magnetic field and the rationality of the designed resonant inductance by detecting the positive and negative currents of the resonant inductance when the pulse voltage is injected. The method only needs to test the potential risk of the system occurring the direct current bias magnetic field fault through the simple pulse voltage injection method, and also verifies the rationality of the resonant inductance. Finally, the bias magnetic field is suppressed by combining the blocking capacitor and the peak current. By injecting the alternating voltage of the positive and negative conversion on the resonant inductance, the voltage and current waveforms are obtained. Through the analysis and calculation of the voltage deviation of the positive and negative half cycles, the reason for the bias magnetic field of the full-bridge direct current converter is obtained in the subsequent work, which provides a basis for the design and selection of the resonant inductance, and effectively improves the reliability of the system.

[0096] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0097] It is to be understood that the embodiments disclosed herein are only illustrative of the principles of this application. Numerous modifications and adaptations will be readily apparent to those skilled in the art without departing from the spirit and scope of the present application. Therefore, the scope of the present application is not intended to be limited to the particular embodiments discussed above, but is only limited by the scope of the appended claims. Accordingly, the specification and drawings are to be regarded simply as illustrative and without limitation.

[0098] In addition, each functional module in each embodiment herein can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0099] Although the present application has been described in detail through the preferred embodiments, it should be recognized that the above description is not to be considered as limiting. Various modifications and alterations will occur to others upon reading the above description. It is intended that the application be construed as including all such modifications and alterations and be limited only by the scope of the appended claims.

Claims

1. A method for analyzing magnetic bias of a full-bridge converter, the method comprising: The method comprises the following steps: Step S1: converting the voltage of the input side capacitor of the full-bridge converter into a pulse voltage through the switching network of the full-bridge converter; Step S2: injecting the pulse voltage into the resonant inductor of the full-bridge converter; Step S3: measuring the voltage signal and the current signal of the resonant inductor; Step S4: analyzing the measured voltage signal and current signal to realize the DC bias analysis of the full-bridge converter; The analysis of the measured voltage signal and current signal is specifically as follows: analyzing the deviation of the voltage signal obtained respectively when the positive half cycle and the negative half cycle of the injected pulse voltage; The specific steps for obtaining the voltage signal when the pulse voltage on the resonant inductor is in the positive half cycle are as follows: Step S4.1: obtaining the difference between the magnetic permeability under two different currents of the full-bridge converter; Step S4.2: obtaining the difference between the inductance under two different currents according to the difference between the magnetic permeability under two different currents obtained in step S4.1; Step S4.3: obtaining the voltage signal, i.e. the voltage of the primary side of the transformer of the full-bridge converter, when the pulse voltage is in the positive half cycle according to the difference between the inductance in step S4.2; The specific steps for obtaining the voltage signal when the pulse voltage on the resonant inductor is in the negative half cycle are as follows: Step S4.4: obtaining the difference between the magnetic permeability under two different currents of the full-bridge converter; Step S4.5: obtaining the difference between the inductance under two different currents according to the difference between the magnetic permeability under two different currents obtained in step S4.4; Step S4.6: obtaining the voltage signal, i.e. the voltage of the primary side of the transformer of the full-bridge converter, when the pulse voltage is in the negative half cycle according to the difference between the inductance in step S4.

5.

2. The full-bridge converter biasing analysis method of claim 1, wherein, In step S3, the voltage signal and the current signal of the resonant inductor are measured to obtain the voltage signal and the current signal, and a waveform diagram of the voltage signal is drawn.

3. The full-bridge converter biasing analysis method of claim 2, wherein, The current signal is obtained by oscilloscope test, and a waveform diagram of the current signal is obtained according to the oscilloscope.

4. The full-bridge converter biasing analysis method of claim 3, wherein, The analysis of the measured current signal specifically comprises: analyzing the magnetic field intensity of the resonant inductor when the current signal increases according to the inductance magnetic circuit law.

5. The full-bridge converter biasing analysis method of claim 4, wherein, The magnetic induction intensity is calculated according to the magnetic field intensity, and a magnetization curve of magnetic induction intensity-magnetic field intensity is drawn according to the magnetic induction intensity and the magnetic field intensity, so as to analyze the magnetic permeability and obtain the inductance of the full-bridge converter.

6. The full-bridge converter biasing analysis method of claim 4, wherein, According to the inductance, the voltage of the primary side of the transformer is analyzed to analyze the deviation of the voltage signal.

7. The full-bridge converter biasing analysis method of claim 6, wherein, The deviation analysis of the voltage signal is realized by analyzing the two voltages of the primary side of the transformer obtained respectively when the pulse voltage is in the positive half cycle and the negative half cycle.

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