Flyback converter with electromagnetic interference suppressing function

Abstract

To provide a flyback converter with an electromagnetic interference suppressing function.SOLUTION: The flyback converter with an electromagnetic interference suppressing function includes an input terminal, an output terminal, a rectifying member, and a transformer. The output terminal includes a first output terminal and a second output terminal. The transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to an input terminal. The upper terminal of the first secondary winding is connected to the first output terminal. The lower terminal of the first secondary winding is connected to a first terminal of the rectifying member. The upper terminal of the second secondary winding is connected to a second terminal of the rectifying member. The lower terminal of the second secondary winding is connected to the second output terminal. With the circuit design of the flyback converter, the generated noise signals cancel each other out, making it possible to effectively suppress electromagnetic interference.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a flyback converter, and more particularly to a flyback converter having an electromagnetic interference suppression function.

Background Art

[0002] Most of the driving power supplies of conventional low-power (less than 200 watts) isolated lighting devices use flyback converters. The driving power supply of the isolated lighting device using a flyback converter is very mature and highly reliable, so it is widely applied.

[0003] However, since serious electromagnetic interference (EMI) occurs during the operation of a flyback converter, it is necessary to reduce electromagnetic interference by a complex filter circuit. However, the above-mentioned filter circuit is usually relatively expensive, which also leads to an increase in the cost of the lighting device. Therefore, how to effectively improve the circuit design of the conventional flyback converter and effectively suppress electromagnetic interference has become an urgent issue.

[0004] Chinese Patent Application Publication No. 104619076 (Patent Document 1) and Chinese Patent Application Publication No. 105871194 (Patent Document 2) disclose an improved converter circuit design, but still cannot effectively solve the problems of the prior art.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a flyback converter having an electromagnetic interference suppression function.

Means for Solving the Problems

[0007] The present invention provides a flyback converter having an electromagnetic interference suppression function, including an input terminal, an output terminal, a rectifying member, and a transformer. The output terminal includes a first output terminal and a second output terminal. The transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the input terminal. The upper terminal of the first secondary winding is connected to the first output terminal, and the lower terminal of the first secondary winding is connected to the first terminal of the rectifying member. The upper terminal of the second secondary winding is connected to the second terminal of the rectifying member, and the lower terminal of the second secondary winding is connected to the second output terminal.

[0008] Based on an improvement of the present invention, the rectifying member is a diode. The lower terminal of the first secondary winding is connected to the negative electrode of the diode, and the upper terminal of the second secondary winding is connected to the positive electrode of the diode.

[0009] Based on an improvement of the present invention, the waveform of the signal passing through the lower end of the first secondary winding is opposite to the waveform of the signal passing through the upper end of the second secondary winding.

[0010] Based on an improvement of the present invention, the number of turns of the first secondary winding is equal to the number of turns of the second secondary winding.

[0011] Based on an improvement of the present invention, the phase of the primary winding is opposite to the phases of the first secondary winding and the second secondary winding.

[0012] Based on an improvement of the present invention, the input terminal includes a first input terminal and a second input terminal. The first input terminal is connected to the upper terminal of the primary winding, and the second input terminal is connected to the lower terminal of the primary winding.

[0013] Based on an improvement of the present invention, the flyback converter further includes a first capacitor. One end of the first capacitor is connected to the first input terminal, and the other end of the first capacitor is connected to the second input terminal.

[0014] Based on an improvement of the present invention, the flyback converter further includes a resistor and a switch member. The second input terminal is connected to the lower terminal of the primary winding via the resistor and the switch member.

[0015] Based on an improvement of the present invention, the switch member is a metal oxide semiconductor field effect transistor (MOSFET), a triode, or other similar members.

[0016] Based on an improvement of the present invention, the flyback converter further includes a second capacitor. One end of the second capacitor is connected to the first output terminal, and the other end of the second capacitor is connected to the second output terminal.

Advantages of the Invention

[0017] Based on the above, the flyback converter with an electromagnetic interference suppression function disclosed in the present invention can have one or more of the following advantages. (1) According to the disclosure of the present invention, the flyback converter includes an input terminal, an output terminal, a rectifying member, and a transformer. The output terminal includes a first output terminal and a second output terminal. The transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the input terminal. The upper terminal of the first secondary winding is connected to the first output terminal, and the lower terminal of the first secondary winding is connected to the first terminal of the rectifying member. The upper terminal of the second secondary winding is connected to the second terminal of the rectifying member, and the lower terminal of the second secondary winding is connected to the second output terminal. Through the structural design of the above primary winding, first secondary winding, second secondary winding, and rectifying member, an effective noise suppression mechanism can be realized, and noise signal propagation paths in two opposite directions can be generated. In this way, the noise signals cancel each other out, and electromagnetic interference can be effectively suppressed. Therefore, the performance of the flyback converter is greatly improved, and the requirements of actual applications can be met. (2) According to the disclosure of the present invention, the flyback converter has a special and effective noise suppression mechanism and can generate two noise signal propagation paths with opposite directions. By the above-mentioned noise suppression mechanism, the noise signal can be effectively canceled without the need for a complex filter circuit, and electromagnetic interference can be effectively suppressed. Therefore, the cost of the flyback converter can be significantly reduced, the application of the flyback converter can be made more extensive, and the requirements of different applications can be met. (3) According to the disclosure of the present invention, the flyback converter has a special and effective noise control mechanism and can effectively suppress electromagnetic interference. Therefore, the performance of the flyback converter can be effectively improved, and at the same time, the performance and reliability of the lighting device can be significantly improved. Therefore, the flyback converter can be more compatible with the future development trend. (4) According to the disclosure of the present invention, the circuit design of the flyback converter can not only realize an effective noise suppression mechanism, but also be applied to various different circuits, without the need to change the circuit design of other functional modules of the lighting device. Therefore, the flyback converter can achieve very high compatibility and make the use of the flyback converter more flexible. (5) According to the disclosure of the present invention, the flyback converter can achieve the desired effect without significantly increasing the cost, and can also improve the performance and reliability of the lighting device. Therefore, the flyback converter can achieve extremely high practicality and meet the requirements of different users.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0019] In the following embodiments, the detailed features and advantages of the present invention will be described. The content is sufficient for those skilled in the art to understand the technical content of the present invention and to enable its implementation accordingly. Moreover, based on the disclosure content, claims, and drawings of this specification, those skilled in the art can easily understand the objectives and advantages of the present invention.

[0020] Hereinafter, with reference to the related drawings, embodiments of a flyback converter having an electromagnetic interference suppression function of the present invention will be described. However, for the sake of easy understanding and easy explanation in the drawings, the members in the drawings may be shown with exaggerated or reduced dimensions and ratios. In the following description and / or claims, when it is stated that a member "connects" or "couples" to another member, it may directly connect or couple to the said another member, or there may be an intervening member. When it is stated that a member "directly connects" or "directly couples" to another member, there is no intervening member, and the same should be interpreted similarly for other terms used to explain the relationship between members or layers. For easy understanding, the same members in the following embodiments will be described with the same reference numerals.

[0021] FIG. 1 is a circuit diagram of a flyback converter having an electromagnetic interference (EMI) suppression function according to the first embodiment of the present invention. As shown in the figure, the flyback converter 1 includes an input terminal Tin, an output terminal Tout, a rectifying member RD, a transformer Tm, a first capacitor C1, a second capacitor C2, a resistor R1, and a switch member MS.

[0022] The input terminal Tin includes a first input terminal P1 and a second input terminal P2. In this embodiment, the first input terminal P1 is a positive input terminal, and the second input terminal P2 is a negative input terminal. In another embodiment, the first input terminal P1 is a negative input terminal, and the second input terminal P2 is a positive input terminal.

[0023] The output terminal Tout includes a first output terminal W1 and a second output terminal W2. In this embodiment, the first output terminal W1 is the positive output terminal, and the second output terminal W2 is the negative output terminal. In other embodiments, the first output terminal W1 is the negative output terminal, and the second output terminal W2 is the positive output terminal.

[0024] The transformer Tm includes a primary winding Pw, a first secondary winding Sw1, and a second secondary winding Sw2. The phase of the primary winding Pw is opposite to the phases of the first secondary winding Sw1 and the second secondary winding Sw2. The number of turns of the first secondary winding Sw1 and the number of turns of the second secondary winding Sw2 may be equal. The primary winding Pw is connected to the input terminal Tin. Here, the first input terminal P1 is connected to the upper terminal Ua of the primary winding Pw, and the second input terminal P2 is connected to the lower terminal La of the primary winding Pw via the resistor R1 and the switch member MS. The upper terminal Ub of the first secondary winding Sw1 is connected to the first output terminal W1, and the lower terminal Lb of the first secondary winding Sw1 is connected to the first terminal of the rectifying member RD. The upper terminal Uc of the second secondary winding Sw2 is connected to the second terminal of the rectifying member RD, and the lower terminal Lc of the second secondary winding Sw2 is connected to the second output terminal W2. In one embodiment, the rectifying member RD is a diode. In another embodiment, the rectifying member RD may be other member having a rectifying function. In one embodiment, the switch member MS is a metal-oxide-semiconductor field-effect transistor (MOSFET). In another embodiment, the switch member MS may be a bipolar junction transistor (BJT) or other similar member.

[0025] One end of the first capacitor C1 is connected to the first input terminal P1, and the other end of the first capacitor C1 is connected to the second input terminal P2.

[0026] One end of the second capacitor C2 is connected to the first output terminal W1, and the other end of the second capacitor C2 is connected to the second output terminal W2.

[0027] Of course, the above circuit design is an example and is not limiting, and can be applied to various conventional flyback converters, and the present invention is not limited thereto.

[0028] From the above, it can be seen that the flyback converter 1 of this embodiment includes an input terminal Tin, an output terminal Tout, a rectifying member RD, and a transformer Tm. The output terminal Tout includes a first output terminal W1 and a second output terminal W2. The transformer Tm includes a primary winding Pw, a first secondary winding Sw1, and a second secondary winding Sw2. The primary winding Sw is connected to the input terminal Tin. The upper terminal Ub of the first secondary winding Sw1 is connected to the first output terminal W1, and the lower terminal Lb of the first secondary winding Sw1 is connected to the first terminal of the rectifying member RD. The upper terminal Uc of the second secondary winding Sw2 is connected to the second terminal of the rectifying member RD, and the lower terminal Lc of the second secondary winding Sw2 is connected to the second output terminal W2. Through the structural design of the aforementioned primary winding Pw1, first secondary winding Sw1, second secondary winding Sw2, and rectifying member RD, an effective noise suppression mechanism can be realized, and noise signal propagation paths with two opposite directions can be generated. In this way, the noise signals cancel each other out, and electromagnetic interference can be effectively suppressed. Therefore, the performance of the flyback converter 1 is greatly improved and can meet the requirements of actual applications.

[0029] According to the above-mentioned noise suppression mechanism, noise signals can be effectively canceled without the need for a complex filter circuit, and electromagnetic interference can be effectively suppressed. Therefore, the cost of the flyback converter 1 can be greatly reduced, the application of the flyback converter 1 can be made more extensive, and different response requirements can be met. At the same time, the performance of the flyback converter 1 can be effectively improved, and the performance and reliability of the lighting device can also be greatly improved. Therefore, the flyback converter 1 can be further applied to the future development trend.

[0030] In addition, the circuit design of the flyback converter 1 can not only realize an effective noise suppression mechanism, but also be applied to various different circuits, and there is no need to change the circuit design of other functional modules of the lighting device. Therefore, the flyback converter 1 can achieve extremely high compatibility and make the use of the flyback converter 1 more flexible.

[0031] Of course, this embodiment is only used for illustrative explanation and does not limit the scope of the present invention. Equivalent modifications or changes made based on the flyback converter with the electromagnetic interference suppression function of this embodiment should still be included in the protection scope of the present invention.

[0032] During the operation of a conventional flyback converter, serious electromagnetic interference occurs, so it is necessary to reduce the electromagnetic interference by a complex filter circuit. However, the above-mentioned filter circuit is usually relatively expensive and also leads to an increase in the cost of the lighting device. In contrast, according to the disclosure content of the first embodiment of the present invention, the flyback converter includes an input terminal, an output terminal, a rectifying member, and a transformer. The output terminal includes a first output terminal and a second output terminal. The transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the input terminal. The upper terminal of the first secondary winding is connected to the first output terminal, and the lower terminal of the first secondary winding is connected to the first terminal of the rectifying member. The upper terminal of the second secondary winding is connected to the second terminal of the rectifying member, and the lower terminal of the second secondary winding is connected to the second output terminal. Through the structural design of the above primary winding, first secondary winding, second secondary winding, and rectifying member, an effective noise suppression mechanism can be realized, and noise signal propagation paths in two opposite directions can be generated. In this way, the noise signals cancel each other out, and electromagnetic interference can be effectively suppressed. Therefore, the performance of the flyback converter is greatly improved, and the actual application requirements can be met.

[0033] Moreover, according to the disclosure of the first embodiment of the present invention, the flyback converter has a special and effective noise suppression mechanism and can generate two noise signal propagation paths with opposite directions. Through the above-mentioned noise suppression mechanism, the noise signal can be effectively canceled without the need for a complex filter circuit, and electromagnetic interference can be effectively suppressed. Therefore, the cost of the flyback converter can be significantly reduced, the application of the flyback converter can be made more extensive, and the requirements of different applications can be met.

[0034] Moreover, according to the disclosure of the first embodiment of the present invention, the flyback converter has a special and effective noise control mechanism and can effectively suppress electromagnetic interference. Therefore, the performance of the flyback converter can be effectively improved, and at the same time, the performance and reliability of the lighting device can be significantly improved. Therefore, the flyback converter can better conform to the trend of future development.

[0035] Moreover, according to the disclosure of the first embodiment of the present invention, the circuit design of the flyback converter can not only realize an effective noise suppression mechanism, but also be applied to various different circuits without the need to change the circuit design of other functional modules of the lighting device. Therefore, the flyback converter can achieve very high compatibility and make the use of the flyback converter more flexible.

[0036] Furthermore, according to the disclosure of the first embodiment of the present invention, the flyback converter can achieve the desired effect without significantly increasing the cost, and can also improve the performance and reliability of the lighting device. Therefore, the flyback converter can achieve extremely high practicality and meet the requirements of different users. From the above, it can be seen that the flyback converter with an electromagnetic interference suppression function based on the embodiment of the present invention can indeed achieve excellent technical results.

[0037] Figure 2 is a circuit diagram of a flyback converter having an electromagnetic interference suppression function according to the second embodiment of the present invention. As shown in the figure, the flyback converter 1 includes an input terminal Tin, an output terminal Tout, a rectifying member RD, a transformer Tm, a first capacitor C1, a second capacitor C2, a resistor R1, and a switch member MS.

[0038] The input terminal Tin includes a first input terminal P1 and a second input terminal P2. In the present embodiment, the first input terminal P1 is a positive input terminal, and the second input terminal P2 is a negative input terminal.

[0039] The output terminal Tout includes a first output terminal W1 and a second output terminal W2. In the present embodiment, the first output terminal W1 is a positive output terminal, and the second output terminal W2 is a negative output terminal.

[0040] The rectifying member RD is connected to the transformer Tm. In the present embodiment, the rectifying member RD is a diode D1.

[0041] The transformer Tm includes a primary winding Pw, a first secondary winding Sw1, and a second secondary winding Sw2. The phase of the primary winding Pw is opposite to the phases of the first secondary winding Sw1 and the second secondary winding Sw2. The number of turns of the first secondary winding Sw1 and the number of turns of the second secondary winding Sw2 may be equal. The primary winding Pw1 is connected to the input terminal Tin. Among them, the first input terminal P1 is connected to the upper terminal Ua of the primary winding Pw, and the second input terminal P2 is connected to the lower terminal La of the primary winding Pw via the resistor R1 and the switch member MS. In this embodiment, the switch member MS is a transistor M1, which may be a metal-oxide-semiconductor field-effect transistor. The second input terminal P2 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the source of the transistor M1. The drain of the transistor M1 is connected to the lower terminal La of the primary winding Pw, and the gate of the transistor M1 is connected to the control power supply. The upper terminal Ub of the first secondary winding Sw1 is connected to the first output terminal W1, and the lower terminal Lb of the first secondary winding Sw1 is connected to the negative electrode of the diode D1. The upper terminal Uc of the second secondary winding Sw2 is connected to the positive electrode of the diode D1, and the lower terminal Lc of the second secondary winding Sw2 is connected to the second output terminal W2.

[0042] One end of the first capacitor C1 is connected to the first input terminal P1, and the other end of the first capacitor C1 is connected to the second input terminal P2.

[0043] One end of the second capacitor C2 is connected to the first output terminal W1, and the other end of the second capacitor C2 is connected to the second output terminal W2.

[0044] Of course, the above circuit design is an example and is not limiting, and it can be applied to various conventional flyback converters, and the present invention is not limited thereto.

[0045] Of course, this embodiment is only used for illustrative purposes and does not limit the scope of the present invention. Equivalent modifications or changes made based on the flyback converter with the electromagnetic interference suppression function of this embodiment should still be included in the protection scope of the present invention.

[0046] Figure 3 is an explanatory diagram of the operating state of a flyback converter having an electromagnetic interference suppression function according to the first embodiment of the present invention. As shown in the figure, the differential mode signal noise sources are the lower terminal Lb of the first secondary winding Sw1 and the upper terminal Uc of the second secondary winding Sw2. Since the waveform WF1 of the signal passing through the lower terminal Lb of the first secondary winding Sw1 is opposite to the waveform WF2 of the signal passing through the upper terminal Uc of the second secondary winding Sw2, the potential of the noise signal at the lower terminal Lb of the first secondary winding Sw1 is opposite to the potential of the noise signal at the upper terminal Uc of the second secondary winding Sw2.

[0047] When the noise signal at the lower terminal Lb of the first secondary winding Sw1 changes from low to high, the above change is coupled from the upper terminal Ub of the first secondary winding Sw1 to the upper terminal Ua of the primary winding Pw through the distributed capacitance Cd. Therefore, the noise signal propagation path of the lower terminal Lb of the first secondary winding Sw1 is PH1. Similarly, the noise signal at the upper terminal Ua of the primary winding Pw is also coupled to the upper terminal Uc of the second secondary winding Sw2. Therefore, the noise signal propagation path of the signal at the upper terminal Ua of the primary winding Pw is PH2.

[0048] With the above circuit design, the waveform of the signal passing through the lower terminal Lb of the first secondary winding Sw1 is opposite to the waveform of the signal passing through the upper terminal Uc of the second secondary winding Sw2, generating two noise signal propagation paths (PH1 and PH2) with opposite directions. In this way, the noise signals cancel each other out, and electromagnetic interference can be effectively suppressed. Therefore, the performance of the flyback converter 1 is greatly improved, and the requirements of actual applications can be met.

[0049] With the above noise suppression mechanism, it is possible to effectively cancel the noise signal without requiring a complex filter circuit, and effectively suppress electromagnetic interference. Therefore, the cost of the flyback converter 1 can be significantly reduced, the application of the flyback converter 1 can be made more extensive, and different response requirements can be satisfied. At the same time, the performance of the flyback converter 1 can be effectively improved, and the performance and reliability of the lighting device can also be significantly improved. Therefore, the flyback converter 1 can be further applied to the trend of future development.

[0050] In addition, the circuit design of the flyback converter 1 can not only realize an effective noise suppression mechanism, but also be applied to various different circuits, and there is no need to change the circuit design of other functional modules of the lighting device. Therefore, the flyback converter 1 can achieve extremely high compatibility and make the use of the flyback converter 1 more flexible.

[0051] Of course, this embodiment is only used for illustrative explanation and does not limit the scope of the present invention. Equivalent modifications or changes made based on the flyback converter with the electromagnetic interference suppression function of this embodiment should still be included in the protection scope of the present invention.

[0052] In summary, according to the disclosure of the first and second embodiments of the present invention, the flyback converter includes an input terminal, an output terminal, a rectifying member, and a transformer. The output terminal includes a first output terminal and a second output terminal. The transformer includes a primary winding, a first secondary winding, and a second secondary winding. The primary winding is connected to the input terminal. The upper terminal of the first secondary winding is connected to the first output terminal, and the lower terminal of the first secondary winding is connected to the first terminal of the rectifying member. The upper terminal of the second secondary winding is connected to the second terminal of the rectifying member, and the lower terminal of the second secondary winding is connected to the second output terminal. Through the structural design of the above primary winding, first secondary winding, second secondary winding, and rectifying member, an effective noise suppression mechanism is realized, and noise signal propagation paths in two opposite directions can be generated. In this way, the noise signals cancel each other out, and electromagnetic interference can be effectively suppressed. Therefore, the performance of the flyback converter is greatly improved, and the requirements of actual applications can be satisfied.

[0053] Also, according to the disclosure of the first and second embodiments of the present invention, the flyback converter has a special and effective noise suppression mechanism and can generate noise signal propagation paths in two opposite directions. Through the above noise suppression mechanism, noise signals can be effectively canceled without the need for a complex filter circuit, and electromagnetic interference can be effectively suppressed. Therefore, the cost of the flyback converter can be greatly reduced, the application of the flyback converter can be made more extensive, and the requirements of different applications can be satisfied.

[0054] Also, according to the disclosure of the first and second embodiments of the present invention, the flyback converter has a special and effective noise control mechanism and can effectively suppress electromagnetic interference. Therefore, the performance of the flyback converter can be effectively improved, and at the same time, the performance and reliability of the lighting device can be greatly improved. Therefore, the flyback converter can better conform to the trend of future development.

[0055] Moreover, according to the disclosure content of the first embodiment and the second embodiment of the present invention, the circuit design of the flyback converter can not only realize an effective noise suppression mechanism, but also be applied to various different circuits, without the need to change the circuit design of other functional modules of the lighting device. Therefore, the flyback converter can achieve very high compatibility and make the use of the flyback converter more flexible.

[0056] Furthermore, according to the disclosure content of the first embodiment and the second embodiment of the present invention, the flyback converter can achieve the desired effect without significantly increasing the cost, and can also improve the performance and reliability of the lighting device. Therefore, the flyback converter can achieve extremely high practicality and meet the requirements of different users.

[0057] Although the above embodiments are described in this specification, it should be noted that they do not limit the scope of the claims of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications to the embodiments described in this specification, or substitutions of equivalent structures or equivalent processes made using the content of the specification and drawings of the present invention, and directly or indirectly applying the above technical solutions to other related technical fields, all fall within the scope of the claims of the present invention.

Explanation of Reference Numerals

[0058] 1 Flyback Converter Tin Input Terminal P1 First Input Terminal P2 Second Input Terminal Tout Output Terminal W1 First Output Terminal W2 Second Output Terminal RD Rectifying Member D1 Diode Tm Transformer Pw Primary Winding Ua Upper Terminal of the Primary Winding La Lower Terminal of the Primary Winding Sw1 First Secondary Winding Upper terminal of the Ub first secondary winding Lower terminal of the Lb first secondary winding Sw2 Second secondary winding Upper terminal of the Uc second secondary winding Lower terminal of the Lc second secondary winding C1 First capacitor C2 Second capacitor Cd Distributed capacitor R1 Resistor MS Switch member M1 Transistor WF1 Waveform of the signal WF2 Waveform of the signal PH1 Noise signal propagation path PH2 Noise signal propagation path

Claims

1. An input terminal; output terminals including a first output terminal and a second output terminal; A straightening member; a transformer including a primary winding, a first secondary winding and a second secondary winding, the primary winding being connected to the input terminal, an upper terminal of the first secondary winding being connected to the first output terminal, a lower terminal of the first secondary winding being connected to a first terminal of the rectifying member, an upper terminal of the second secondary winding being connected to a second terminal of the rectifying member, and a lower terminal of the second secondary winding being connected to the second output terminal; A flyback converter with electromagnetic interference suppression including:

2. 2. The flyback converter with electromagnetic interference suppression function according to claim 1, characterized in that the rectifying member is a diode, a lower terminal of the first secondary winding is connected to a negative electrode of the diode, and an upper terminal of the second secondary winding is connected to a positive electrode of the diode.

3. 2. The flyback converter with electromagnetic interference suppression function according to claim 1, wherein a waveform of a signal passing through the lower terminal of the first secondary winding is inverse to a waveform of a signal passing through the upper terminal of the second secondary winding.

4. 2. The flyback converter with electromagnetic interference suppression function according to claim 1, wherein the number of turns of the first secondary winding is equal to the number of turns of the second secondary winding.

5. 2. The flyback converter with electromagnetic interference suppression function according to claim 1, wherein the phase of the primary winding is opposite to the phases of the first secondary winding and the second secondary winding.

6. 2. The flyback converter with an electromagnetic interference suppressor according to claim 1, wherein the input terminal includes a first input terminal and a second input terminal element, the first input terminal being connected to an upper terminal of the primary winding, and the second input terminal being connected to a lower terminal of the primary winding.

7. 7. The flyback converter with electromagnetic interference suppression function according to claim 6, further comprising a first capacitor, one end of the first capacitor being connected to the first input terminal, and the other end of the first capacitor being connected to the first input terminal.

8. 7. The flyback converter with electromagnetic interference suppression function according to claim 6, further comprising a resistor and a switch member, wherein the second input terminal is connected to a lower terminal of the primary winding via the resistor and the switch member.

9. 9. The flyback converter with electromagnetic interference suppression function as claimed in claim 8, wherein the switch member is a gold-oxide field effect transistor or a triode.

10. 2. The flyback converter with electromagnetic interference suppression function according to claim 1, further comprising a second capacitor, one end of the second capacitor being connected to the first output terminal, and the other end of the second capacitor being connected to the second output terminal.

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