A switching circuit and power supply device

Abstract

The application provides a switching circuit and a power supply device. The switching circuit comprises at least one switching tube, a metal unit (20) and a first branch (21). The metal unit (20) is arranged on the switching tube. The first branch (21) is electrically connected between the switching tube and the ground. Alternatively, the first branch (21) is electrically connected between the metal unit (20) and the ground. The first branch (21) comprises a first capacitor (C1) for discharging radiation interference. In this way, the radiation interference can be reduced while the heat dissipation effect is maintained, and the volume is relatively small.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a switching circuit and power supply device. Background Technology

[0002] Currently, in applications using switching transistors, the transistors typically generate heat due to losses such as turn-on losses, turn-off losses, and conduction losses. Therefore, a heat sink is required to dissipate heat from the switching transistor. Since metals have good thermal conductivity, heat sinks are usually made of metal.

[0003] However, switching transistors generate electromagnetic interference (EMI) when they are turned on and off, and radiate electromagnetic interference, which is called radiated interference. Furthermore, the use of metal heat sinks can increase the volume of the radiated interference propagation medium, leading to an increase in radiated interference.

[0004] In existing technologies, a shielding cover is typically added to completely cover the heat sink to reduce radiation interference. However, this approach increases the size of the heat sink and may also lead to poorer heat dissipation. Summary of the Invention

[0005] This application aims to provide a switching circuit and power supply device that can reduce radiation interference while maintaining heat dissipation and has a smaller size.

[0006] To achieve the above objectives, in a first aspect, this application provides a switching circuit, including at least one switching transistor, a metal unit, and a first branch. The metal unit is disposed on the switching transistor. The first branch is electrically connected between the switching transistor and ground, and / or, the first branch is electrically connected between the metal unit and ground. The first branch includes a first capacitor for discharging radiated interference.

[0007] By setting a first capacitor, a discharge circuit can be formed to discharge radiated interference generated by the switching transistor, and also to further discharge radiated interference amplified by the metal unit. This helps reduce the risk of abnormalities caused by interference to various electronic components in the circuit, thereby improving the stability of the circuit during operation. Furthermore, compared to adding a shielding cover, the first capacitor added in this application has a smaller impact on the heat dissipation of the metal unit, thus maintaining the heat dissipation effect of the metal unit. Additionally, the volume of the added first capacitor is smaller than that of adding a shielding cover, which helps reduce the overall size of the switching circuit and saves circuit design costs.

[0008] In one alternative embodiment, the first branch further includes a first resistor. The first resistor is connected in series with the first capacitor.

[0009] Adding a first resistor helps to dissipate more radiated interference, thereby improving the stability of the switching circuit.

[0010] In one alternative embodiment, the first branch also includes a second capacitor. The first capacitor and the second capacitor are connected in series.

[0011] Adding a second capacitor increases the withstand voltage of the first branch, making it suitable for various applications with different voltages, thereby improving the practicality of the switching circuit.

[0012] In one alternative embodiment, at least one switching transistor includes at least two switching transistors. The metal unit includes metal sub-units corresponding to each switching transistor, wherein each first switching transistor has one metal sub-unit. The first branch includes first sub-branches corresponding to each metal sub-unit, wherein each first sub-branch is electrically connected between a metal sub-unit and ground.

[0013] When each switching transistor has a metal sub-unit, a first sub-branch can be set between each metal sub-unit and ground to discharge the radiated interference amplified by each metal sub-unit. This allows for more thorough discharge, which helps to reduce radiated interference to a greater extent and thus improves the stability of the circuit operation.

[0014] In one alternative embodiment, at least one switch comprises at least two bridge arms connected in parallel, wherein each bridge arm comprises two switches connected in series. A first branch includes second sub-branches corresponding to a bridge arm, wherein each second sub-branch is electrically connected between a bridge arm and ground.

[0015] When a circuit includes at least two bridge arms connected in parallel, a second sub-branch can be provided in each bridge arm to discharge electromagnetic interference.

[0016] In an alternative embodiment, the switching circuit further includes a first pad. The first pad is disposed between the switching transistor and the metal unit.

[0017] A first gasket is placed between the switching transistor and the metal unit to serve as an isolation device.

[0018] In one alternative approach, the capacitance of the first capacitor ranges from 1nF to 10nF, where nF represents the unit of capacitance, nanofarad.

[0019] When the capacitance of the first capacitor is in the range of 1nF-10nF, the discharge effect on radiated interference is better. Furthermore, within this range, the discharge effect increases with the increase of capacitance.

[0020] In an alternative embodiment, the switching circuit also includes a filter branch. The filter branch is connected to both the AC power supply and the switching transistor, and is used to filter out differential-mode and common-mode interference from the AC power supply.

[0021] By filtering out differential-mode and common-mode interference in the AC power supply, a more stable AC power supply can be provided for subsequent circuits, which helps to improve the stability of the circuit during operation.

[0022] Secondly, this application also provides a power supply device, including the switching circuit as described in any of the above embodiments.

[0023] In one alternative approach, the power supply device is a switching power supply or a charging station.

[0024] The beneficial effects of the embodiments of this application are as follows: The switching circuit provided by this application, by electrically connecting a first branch between the switching transistor and ground, and / or between the metal unit and ground, and by discharging radiated interference through the first capacitor in the first branch, can not only discharge radiated interference generated by the switching transistor, but also further discharge radiated interference amplified by the metal unit. This helps reduce the risk of abnormalities caused by interference to various electronic components in the circuit, thereby improving the stability of the circuit during operation. Secondly, compared with the technical solution of adding a shield in the prior art, the first capacitor added in this application has a smaller impact on the heat dissipation of the metal unit, that is, it can maintain the heat dissipation effect of the metal unit. At the same time, the volume of the added first capacitor is also smaller than the volume of adding a shield, which helps to reduce the overall size of the circuit and save circuit design costs. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the shielding cover and MOSFET disclosed in the prior art;

[0027] Figure 2 This is a schematic diagram of an application scenario disclosed in an embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the structure of a switching circuit disclosed in an embodiment of this application;

[0029] Figure 4 This is a schematic diagram of the switching circuit disclosed in another embodiment of this application;

[0030] Figure 5This is a schematic diagram of the switching circuit disclosed in another embodiment of this application;

[0031] Figure 6 This is a schematic diagram of the switching circuit disclosed in another embodiment of this application;

[0032] Figure 7 This is a schematic diagram of the switching circuit disclosed in another embodiment of this application;

[0033] Figure 8 This is a schematic diagram of the switching circuit disclosed in another embodiment of this application;

[0034] Figure 9 This is a schematic diagram of the switching circuit disclosed in another embodiment of this application;

[0035] Figure 10 This is a schematic diagram of the structure of the first gasket, switching transistor and metal unit disclosed in an embodiment of this application;

[0036] Figure 11 This is a schematic diagram of the circuit structure of a switching circuit disclosed in an embodiment of this application;

[0037] Figure 12 This is a schematic diagram of the waveform of radiated interference without the addition of a first branch, as disclosed in an embodiment of this application;

[0038] Figure 13 This is a schematic diagram of the waveform of radiated interference after adding a first branch, as disclosed in an embodiment of this application;

[0039] Figure 14 This is a schematic diagram of the circuit structure of a switching circuit disclosed in another embodiment of this application.

[0040] The accompanying drawings are not drawn to scale. Detailed Implementation

[0041] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0042] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0043] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the shielding cover and MOSFET structure disclosed in the prior art. (Example:) Figure 1 As shown, a heat sink 11 is provided on the MOSFET 10 for heat dissipation. In practical applications, the switching frequency of the switching transistor is generally tens of kHz or even hundreds of kHz, meaning that the dv / dt and di / dt of the switching transistor are relatively large. This causes the switching transistor to radiate electromagnetic interference at high frequencies during the switching process, resulting in a large amount of radiated interference that continues to increase. In order to reduce the adverse effects of the radiated interference generated by the MOSFET 10 on the normal operation of other electronic devices, a shielding cover 10 can be used to cover the MOSFET 10 and the heat sink 11 from top to bottom.

[0045] However, the above method requires a large shielding cover, which increases the size of the entire circuit and the devices containing it. Furthermore, as the number of MOSFETs 10 increases, the number of shielding covers also increases accordingly, leading to higher overall circuit costs and reduced practicality. In addition, the increased shielding covers may also worsen heat dissipation, increasing the risk of damage to electronic components such as the MOSFETs 10.

[0046] Based on this, embodiments of this application provide a switching circuit that forms a discharge loop by adding a branch including a first capacitor. This discharge loop is used to discharge radiated interference generated by the switching transistor in the switching circuit. Thus, radiated interference can be reduced while maintaining heat dissipation, and the circuit is also smaller in size.

[0047] The switching circuit disclosed in this application can be used, but is not limited to, in power supply devices such as switching power supplies or charging piles. A power supply system composed of a power supply device equipped with the switching circuit disclosed in this application can be used, thus providing a more stable operating power supply to the power supply system and improving the stability of the power supply system's operation.

[0048] To facilitate understanding of this application, we will first introduce one applicable application scenario. For example... Figure 2 As shown, this application scenario includes an electric vehicle 21, a charging pile 22, and an interface 23. The charging pile 22 includes a power conversion module 221, a charging cable 222, and a power cable 223.

[0049] Power cord 223 is used to connect to an external input power source (e.g., AC mains power) via interface 23 (e.g., a socket) to obtain an input voltage. Power conversion module 221 includes a switching circuit as described in any embodiment of this application to obtain a relatively stable voltage that can be used to power a load based on the input voltage. In this embodiment, power conversion module 221 is used to convert the obtained input voltage into a voltage that can be used to charge electric vehicle 21. This voltage is then transmitted to electric vehicle 21 via charging cable 222 to charge electric vehicle 21.

[0050] It should be noted that in this implementation, the power supply device is used as an example of a charging pile. In other embodiments, the power supply device can also be, but is not limited to, an on-board charger, a non-on-board charger, and a switching power supply, etc.

[0051] Please see Figure 3 , Figure 3 This is a schematic diagram of the switching circuit disclosed in one embodiment of this application. Figure 3 As shown, the switching circuit includes a metal unit 20, a first branch 21, and at least one switching transistor. The at least one switching transistor includes switching transistor Q1, switching transistor Q2…switching transistor Qn, where n is a positive integer. The first branch 21 includes a first capacitor C1.

[0052] The metal unit 20 may include a material that is glossy, has good electrical conductivity, thermal conductivity and mechanical properties, and has a positive temperature resistivity, such as aluminum or copper, etc., but the embodiments of this application do not limit this.

[0053] Specifically, the metal unit 20 can be disposed on the switching transistors Q1, Q2, ... Qn in the direction indicated by the arrow. In one embodiment, the metal unit 20 can be as follows: Figure 1 The transistors are installed in the manner shown on the switching transistors Q1, Q2, ... Qn. The first branch 21 is electrically connected between the switching transistors Q1, Q2, ... Qn and ground, and can discharge radiated interference through the first capacitor C1.

[0054] Among these, radiated interference is generated during the rapid switching process of the switching transistor, and the metal unit 20 may increase the volume of radiated interference propagation, further increasing the radiated interference. By setting the first capacitor C1, a discharge circuit can be provided to effectively reduce radiated interference, which helps to reduce the risk of abnormal operation of the switching circuit due to radiated interference, thereby improving the stability of the switching circuit operation.

[0055] Meanwhile, compared to the existing technology that adds a shielding cover, the first branch 21 in this application has a smaller impact on the heat dissipation of the metal unit 20, allowing the metal unit 20 to maintain a better heat dissipation effect. On the other hand, the volume of the first branch 21 is also smaller than that of adding a shielding cover, which helps to reduce the volume of the entire switching circuit and saves circuit design costs.

[0056] It should be noted that in this embodiment, the first branch 21 is electrically connected between the switching transistors Q1, Q2...Qn and ground. In another embodiment, as shown... Figure 4 As shown, the first branch 21 can also be electrically connected between the metal unit 20 and ground. In another embodiment, as... Figure 5 As shown, the first branch 21 can be electrically connected not only between the metal unit 20 and ground, but also simultaneously electrically connected between the switching transistors Q1, Q2...Qn and ground. Among these, in... Figure 3 or Figure 4 or Figure 5 In the embodiments shown, the purpose of dissipating radiated interference through the first capacitor C1 can be achieved.

[0057] In addition, each switching transistor can be a metal-oxide-semiconductor field-effect transistor, an insulated-gate bipolar transistor, or other switching elements, and the embodiments of this application do not limit this.

[0058] In one embodiment, the first branch 21 further includes a first resistor. The first resistor is connected in series with the first capacitor. Figure 3 The structure shown is further illustrated using a first resistor as an example.

[0059] like Figure 6As shown, the first branch 21 includes a first resistor R1 and a first capacitor C1 connected in series. The positions of the first resistor R1 and the first capacitor C1 can be interchanged, that is, the switching transistors Q1, Q2...Qn can be connected to the first capacitor C1 and the first resistor R1 in sequence, or the switching transistors Q1, Q2...Qn can also be connected to the first resistor R1 and the first capacitor C1 in sequence.

[0060] By increasing the first resistor R1, it is beneficial to dissipate radiated interference more quickly and in greater quantities, thereby further improving the stability of the switching circuit during operation.

[0061] It is understood that the first branch 21 provided in this embodiment can be applied to, for example... Figure 4 or Figure 5 The circuit structure shown is readily understood by those skilled in the art and will not be described in detail here.

[0062] In one embodiment, the first branch 21 further includes a second capacitor, which is connected in series with the first capacitor. Figure 3 The structure shown is further illustrated by including a second capacitor as an example.

[0063] like Figure 7 As shown, the first branch 21 includes a second capacitor C2 and a first capacitor C1 connected in series.

[0064] In one embodiment, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 can be set to be equal, so that the total capacitance value of the circuit formed by the series connection of the first capacitor C1 and the second capacitor C2 is equal to the capacitance value of the first capacitor C1. On the one hand, by keeping the capacitance value constant, the capacitance value can be kept at a low value, which helps to reduce abnormalities such as short circuits in the switching circuit caused by excessive capacitance value; on the other hand, by connecting multiple capacitors in series, the withstand voltage value of the first branch 21 can be increased to be suitable for various application scenarios with different voltages, thereby improving the practicality of the switching circuit.

[0065] It is understood that the first branch 21 provided in this embodiment can also be applied to, for example, Figure 4 or Figure 5 The circuit structure shown is readily understood by those skilled in the art and will not be described in detail here.

[0066] Meanwhile, in the embodiments of this application, the content related to the first branch 21 can be used alone or in combination, and the embodiments of this application do not impose any restrictions on this. For example, in one embodiment, the content related to the first branch 21 can be... Figure 6 and Figure 7 The structure of the first branch 21 shown is such that, in this embodiment, the first branch 21 includes a first capacitor C1, a second capacitor C2, and a first resistor R1 connected in series.

[0067] In one embodiment, it is possible to Figure 3 In the circuit structure shown, n is set to a positive integer greater than 1, meaning that the switching circuit includes at least two switching transistors.

[0068] Please see Figure 8 The metal unit 20 includes metal subunits M1, M2, ..., Mn. Metal subunit M1 is located on switch Q1, metal subunit M2 is located on switch Q2, ..., metal subunit Mn is located on switch Qn. That is, each metal subunit corresponds one-to-one with a switch, and each switch has one metal subunit.

[0069] In this embodiment, the first branch 21 needs to include a first sub-branch L1, a first sub-branch L2, ..., a first sub-branch Ln, and the first sub-branch corresponds one-to-one with the metal sub-unit. At this time, the first sub-branch L1 is electrically connected between the metal sub-unit M1 and ground, the first sub-branch L2 is electrically connected between the metal sub-unit M2 and ground, ..., the first sub-branch Ln is electrically connected between the metal sub-unit Mn and ground. That is, each metal sub-unit is connected to ground by a first sub-branch.

[0070] It is understandable that the structure of any first sub-branch can be similar to... Figure 3 , Figure 4 , Figure 5 , Figure 6 or Figure 7 The structure of the first branch 21 is the same. Therefore, the radiated interference amplified by each metal sub-unit can be discharged, which can make the radiated interference discharge more complete, which is conducive to reducing radiated interference to a greater extent and thus improving the stability of the circuit operation.

[0071] Secondly, in this embodiment, the number of metal sub-units is equal to the number of switching transistors. In other embodiments, the number of metal sub-units may not be equal to the number of switching transistors. For example, multiple switching transistors may share a single metal sub-unit. In this case, by setting up a first sub-branch according to the number of metal sub-units, the radiated interference amplified by each metal sub-unit can also be discharged.

[0072] In one embodiment, the switching circuit includes at least two bridge arms. For example... Figure 9 As shown, the switching circuit includes bridge arms A1, A2, ..., Ak, where k is a positive integer greater than 1. Bridge arm A1 includes switching transistors Q1 and Q2, bridge arm A2 includes switching transistors Q3 and Q4, ..., bridge arm Ak includes switching transistors Qn-1 and Qn, that is, each bridge arm includes two switching transistors.

[0073] Subsequently, in this embodiment, the first branch 21 includes second sub-branches corresponding to one bridge arm. That is, the first branch 21 includes second sub-branches L11, L12, ..., L1k. Each second sub-branch is electrically connected between a bridge arm and ground; that is, second sub-branch is electrically connected between bridge arm A1 and ground, second sub-branch is electrically connected between bridge arm A2 and ground, ..., second sub-branch is electrically connected between bridge arm Ak and ground.

[0074] It is understandable that the structure of any second sub-branch can be similar to... Figure 3 , Figure 4 , Figure 5 , Figure 6 or Figure 7 The structure of the first branch 21 is the same. Therefore, the radiated interference generated by each bridge arm can be discharged, and the discharge of radiated interference can be more complete, which is beneficial to improving the stability of circuit operation.

[0075] In one embodiment, the switching circuit further includes a first pad disposed between the switching transistor and the metal unit. The first pad can be used to isolate the switching transistor from the metal unit to reduce the risk of electric shock that may occur due to voltage or current on the switching transistor being conducted through the metal unit.

[0076] For example, let's take the switching transistor Q1 as an example, with the metal unit serving as a heat sink. Figure 10 As shown, a first gasket 22 is placed between the switching transistor Q1 and the metal unit 20. Since the heat generated by the switching transistor Q1 due to its turn-on, turn-off, and conduction losses is unavoidable, a metal unit 20 (i.e., a heat sink) is needed on the switching transistor Q1 for heat dissipation to extend its service life. Simultaneously, since the switching transistor Q1 carries voltage or current, the first gasket 22 can be placed between the switching transistor Q1 and the metal unit 20. This first gasket 22 should be made of an insulating material with thermal conductivity to transfer heat from the switching transistor Q1 to the metal unit 20, thereby completing the heat dissipation process of the switching transistor Q1.

[0077] In one embodiment, the capacitance range of the first branch 21 is 1nF-10nF, where nF represents the unit nanofarad of capacitance. For example, as... Figure 3 As shown, when the first branch 21 includes the first capacitor C1, the capacitance range of the first capacitor C1 is 1nF-10nF. For example, as... Figure 7 As shown, when the first branch 21 includes the first capacitor C1 and the second capacitor C2, the total capacitance of the first capacitor C1 and the second capacitor C2 ranges from 1nF to 10nF.

[0078] When the capacitance of the first branch 21 is in the range of 1nF-10nF, the first branch 21 can effectively discharge radiated interference. Furthermore, within this range, the discharge effect increases with the increase of capacitance.

[0079] In one embodiment, the switching circuit further includes a filter branch connected to both the AC power supply and the switching transistor. The filter branch is used to filter out differential-mode interference and common-mode interference from the AC power supply. Common-mode interference is defined as an undesirable potential difference between any current-carrying conductor and ground. Differential-mode interference is defined as an undesirable potential difference between any two current-carrying conductors.

[0080] Specifically, with Figure 11 The circuit structure of an exemplary switching circuit shown is used as an example for illustration. Figure 11 As shown, the switching circuit includes a metal unit 20, a first branch 21, and a filter branch 23. The switching circuit also includes switching transistors Q1, Q2…Qn, and a first spacer, wherein the first spacer can be equivalent to a parasitic capacitor C11 with a small capacitance value. In this embodiment, the first branch 21 is described as including only the first capacitor C1. The filter branch 21 is electrically connected between the AC power supply AC and each switching transistor, the parasitic capacitor C11 is electrically connected between each switching transistor and the metal unit 20, and the first capacitor C1 is electrically connected between the metal unit 20 and ground (or the casing of the device including the switching circuit).

[0081] Specifically, the first capacitor C1 provides a discharge circuit for the radiated interference generated by each switching transistor. This discharge circuit sequentially includes the metal unit 20, the first capacitor C1, the filter branch 23, each switching transistor, the parasitic capacitance C11, and the metal unit 20. Thus, the radiated interference passing through the metal unit 20 is consumed in this discharge circuit, thereby significantly reducing the radiated interference value.

[0082] Please refer to the following: Figure 12 and Figure 13 , Figure 12 The radiated interference without the addition of the first branch 21 is shown. Figure 13 The diagram illustrates the radiated interference after adding the first branch 21. Waveforms B1 and B2 represent the radiated interference waveforms; waveform B0 represents the safe threshold for radiated interference. Only when the radiated interference is below this safe threshold can its impact on other electronic devices be approximately negligible.

[0083] Specifically, such as Figure 12 As shown, if the first branch 21 is not added to the switching circuit, in the frequency band between 35MHz and 50MHz, waveform B1 exceeds waveform B0, meaning the radiated interference exceeds the safety threshold. Furthermore, as... Figure 13As shown, after adding the first branch 21, in the frequency band between 35MHz and 50MHz, waveform B2 is mostly smaller than waveform B0, meaning that most of the radiated interference has been reduced to below the safe threshold. The reduction in radiated interference is particularly significant at around 40MHz, with a reduction of approximately 10dB.

[0084] It is evident that by adding the first branch 21, radiated interference can be significantly reduced, which is beneficial for protecting the electronic components in the switching circuit and thus extending their service life. Simultaneously, it also improves the stability of the switching circuit. Secondly, the added first capacitor C1 is electrically connected between the metal unit 20 and ground, which reduces the probability of a short circuit in the first capacitor C1, thereby protecting it.

[0085] It is understood that in this embodiment, the first branch 21 is electrically connected between the metal unit 20 and ground. In other embodiments, the first branch 21 can also be electrically connected between each switching transistor and ground. The specific implementation method has been described in the above embodiments and will not be repeated here.

[0086] In one embodiment, the filter branch 23 includes a first safety capacitor CY1, a second safety capacitor CY2, a third safety capacitor CX1, a fourth safety capacitor CX2, a common-mode inductor T1, and a magnetizing inductor T2. The first safety capacitor CY1 is electrically connected between the first terminal of the AC power supply AC and ground; the second safety capacitor CY2 is electrically connected between the second terminal of the AC power supply AC and ground; the third safety capacitor CX1 is electrically connected between the first and second terminals of the AC power supply AC; the first terminal of the common-mode inductor T1 is electrically connected to the first terminal of the AC power supply AC, the second terminal of the common-mode inductor T1 is electrically connected to the second terminal of the AC power supply AC, the first terminal of the common-mode inductor T1 is connected to the first terminal of the fourth safety capacitor CX2, and the second terminal of the common-mode inductor T1 is connected to the second terminal of the fourth safety capacitor CX2; the first terminal of the fourth safety capacitor CX2 is also electrically connected to each switching transistor via the magnetizing inductor T2, and the second terminal of the fourth safety capacitor CX2 is electrically connected to each switching transistor.

[0087] Specifically, the first safety capacitor CY1 and the second safety capacitor CY2 are used to eliminate differential-mode interference. The third safety capacitor CX1 and the fourth safety capacitor CX2 are used to eliminate common-mode interference. The common-mode inductor T1 is used to filter out common-mode electromagnetic interference on the signal lines and also to suppress its own electromagnetic interference, thus avoiding affecting the normal operation of other electronic devices in the same electromagnetic environment. The magnetizing inductor T2 is used to achieve voltage boost or buck.

[0088] In this embodiment, a safety capacitor refers to a capacitor that will not cause electric shock or endanger personal safety if it fails. Therefore, by selecting safety capacitors for each capacitor, the safety of the switching circuit during operation can be improved. Of course, other types of capacitors can be used in other embodiments, and this application does not impose any limitations on the comparison of embodiments. Furthermore, this embodiment, by filtering out differential-mode interference and common-mode interference in the AC power supply, can provide a more stable AC power supply for subsequent circuits, which is beneficial to improving the stability of the circuit during operation.

[0089] It should be noted that, as Figure 11 The circuit structure of the switching circuit shown is merely an example, and the switching circuit may have more or fewer components than shown in the figure, may combine two or more components, or may have different component configurations; this application does not limit this. For example, in one embodiment, the switching circuit may be a resonant bidirectional full-bridge DC / DC converter circuit. As another example, in another embodiment, the switching circuit may also be a phase-shifted full-bridge circuit.

[0090] Among them, the resonant bidirectional full-bridge DC / DC converter circuit can be as follows: Figure 14 As shown in the diagram, in this circuit, switching transistors S141, S142, S143, S144, S145, S146, and S148 can all be provided with metal units. Furthermore, a first branch can be provided between each switching transistor and ground, and / or between the metal unit and ground, to mitigate the discharge radiation interference generated by each switching transistor. The specific implementation process has been described in the above embodiments and will not be repeated here.

[0091] This application provides a power supply device, which includes the switching circuit described in any of the above embodiments. The power supply device can be a device that obtains energy from the power grid, converts it, and then provides electrical energy to one or more loads.

[0092] In one embodiment, the power supply device is a switching power supply or a charging station. The switching power supply or charging station can obtain input voltage from mains power and convert the input voltage into a voltage usable by other devices.

[0093] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A switching circuit, comprising: At least one switching transistor; A metal unit, wherein the metal unit is disposed on the switching transistor; The first branch is electrically connected between the switch and ground; or, the first branch is electrically connected between the switch and ground and the first branch is also electrically connected between the metal unit and ground. The first branch includes a first capacitor, which is used to discharge radiated interference.

2. The switching circuit according to claim 1, wherein, The first branch also includes a first resistor; The first resistor is connected in series with the first capacitor.

3. The switching circuit according to claim 1, wherein, The first branch also includes a second capacitor; The first capacitor and the second capacitor are connected in series.

4. The switching circuit according to claim 1, wherein, The at least one switching transistor includes at least two switching transistors; The metal unit includes metal sub-units corresponding to each of the switching transistors, wherein each of the switching transistors is provided with a metal sub-unit; The first branch includes a first sub-branch corresponding to each of the metal sub-units, wherein any of the first sub-branches is electrically connected between a metal sub-unit and ground.

5. The switching circuit according to claim 1, wherein, The at least one switch includes at least two bridge arms connected in parallel, wherein the bridge arm includes two switch elements connected in series; The first branch includes a second sub-branch corresponding to each of the bridge arms, wherein any second sub-branch is electrically connected between a bridge arm and ground.

6. The switching circuit according to claim 1, wherein, The switching circuit also includes a first pad; The first gasket is disposed between the switching transistor and the metal unit.

7. The switching circuit according to any one of claims 1-6, wherein, The capacitance range of the first capacitor is 1nF-10nF, where nF represents the unit of capacitance, nanofarad.

8. The switching circuit according to any one of claims 1-6, wherein, The switching circuit also includes a filtering branch; The filter branch is connected to the AC power supply and the switching transistor respectively, and the filter branch is used to filter out differential mode interference and common mode interference in the AC power supply.

9. A power supply device, comprising: The switching circuit as described in any one of claims 1-8.

10. The power supply device according to claim 9, wherein, The power supply device is a switching power supply or a charging pile.

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