Switch circuit and power supply device

Abstract

The present application provides a switch circuit and a power supply device, the switch circuit including at least one switching transistor, a metal unit, and a first branch circuit, the metal unit being disposed on the switching transistor, the first branch circuit being electrically connected between the switching transistor and ground, and / or the first branch circuit being electrically connected between the metal unit and ground, wherein the first branch circuit includes a first capacitor for dissipating radiated interference. This method can maintain heat dissipation effect, reduce radiated interference, and have a small volume.

Description

[Technical Field]

[0001] The present application relates to the field of electronic circuits, and more particularly to switch circuits and power supply devices. [Background technology]

[0002] Currently, in applications where switching transistors are used, the switching transistors often generate heat due to losses such as turn-on loss, turn-off loss, and conduction loss. In order to dissipate the heat from the switching transistors, it is necessary to attach a heat sink to the switching transistor. In addition, due to the high thermal conductivity of metals, metal materials are usually selected for the heat sink.

[0003] However, switching transistors generate electromagnetic interference (EMI) when they are turned on and off, radiating and emitting radio wave interference, i.e., radiated interference. Selecting a metal heat sink can increase the volume of the propagation medium for radiated interference, which can lead to an increase in radiated interference.

[0004] In the prior art, in order to reduce radiation interference, it is usually necessary to add a shielding case to completely cover the heat sink, but this increases the volume and may also reduce the heat dissipation effect. Summary of the Invention [Problem to be solved by the invention]

[0005] The present application aims to provide a switch circuit and a power supply device that can maintain heat dissipation effect, reduce radiation interference, and have a small volume. [Means for solving the problem]

[0006] To achieve the above object, according to a first aspect, the present application provides a switch circuit, the switch circuit including at least one switching transistor, a metal unit, and a first branch circuit, where the metal unit is provided on the switching transistor, the first branch circuit is electrically connected between the switching transistor and ground, and / or the first branch circuit is electrically connected between the metal unit and ground, and the first branch circuit includes a first capacitor for dissipating radiated interference.

[0007] The installation of the first capacitor forms a relief circuit for dissipating radiated interference generated in the switching transistor, and is also used to further dissipate radiated interference amplified by the metal unit, which is advantageous in reducing the risk of malfunctions caused by interference in each electronic device in the circuit and thereby improving the stability of the circuit during operation.In addition, compared to the technical solution of adding a shielding case, on the one hand, the added first capacitor in this application has a small impact on the heat dissipation of the metal unit, i.e., the heat dissipation effect of the metal unit can be maintained, and on the other hand, the volume of the added first capacitor is smaller than the volume of the added shielding case, which reduces the volume of the entire switch circuit and is advantageous in saving circuit design costs.

[0008] In an optional embodiment, the first branch circuit further includes a first resistor connected in series with the first capacitor.

[0009] By adding the first resistor, it is advantageous to consume more radiated interference and improve the operation stability of the switch circuit.

[0010] In an optional embodiment, the first branch circuit further includes a second capacitor, the first capacitor and the second capacitor being connected in series.

[0011] Adding the second capacitor is advantageous to increase the withstand voltage value of the first branch circuit, so that the first branch circuit can be applied to multiple application scenarios with different voltages, thereby improving the practicality of the switch circuit.

[0012] In an optional embodiment, the at least one switching transistor includes at least two switching transistors, the metal unit includes metal subunits corresponding to the switching transistors in a one-to-one relationship, where any one first switching transistor is provided with one metal subunit, and the first branch circuit includes first sub-branch circuits corresponding to the metal subunits in a one-to-one relationship, where any one first sub-branch circuit is electrically connected between the metal subunit and ground.

[0013] When each switching transistor is provided with one metal subunit, a first sub-branch circuit can be installed between each metal subunit and ground to dissipate the radiated interference amplified by each metal subunit, which can provide more sufficient dissipation and significantly reduce the radiated interference, thereby improving the stability of the circuit operation.

[0014] In an optional embodiment, the at least one switching transistor includes at least two bridge arms connected in parallel, where each bridge arm includes two switching transistors connected in series, and the first branch circuit includes second sub-branch circuits corresponding to the bridge arms one-to-one, where any one of the second sub-branch circuits is electrically connected between the bridge arm and ground.

[0015] When the circuit includes at least two bridge arms connected in parallel, each bridge arm can be provided with a second sub-branch circuit to achieve the purpose of escaping radio interference.

[0016] In an optional embodiment, the switch circuit further includes a first gasket disposed between the switching transistor and the metal unit.

[0017] A first gasket is provided between the switching transistor and the metal unit to perform an isolation function.

[0018] In an optional form, the first capacitor has a capacitance range of 1 nF-10 nF, where nF represents nanofarad, a unit of capacitance.

[0019] When the capacitance of the first capacitor is in the range of 1 nF-10 nF, the dissipation effect against radiated interference is better, and within this range, the dissipation effect improves with increasing capacitance.

[0020] In an optional aspect, the switch circuit further includes a filtering sub-circuit, the filtering sub-circuit connected to the AC power supply and the switching transistor, respectively, the filtering sub-circuit for filtering out differential mode interference and common mode interference in the AC power supply.

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

[0022] According to a second aspect, the present application further provides a power supply device, the power supply device including the switch circuit of any one of the above embodiments.

[0023] In an optional aspect, the power supply is a switching power supply or a charging stand.

[0024] The advantageous effects of the embodiments of the present application are as follows: the switch circuit of the present application electrically connects a first branch circuit between the switching transistor and ground and / or between the metal unit and ground, and the first capacitor in the first branch circuit dissipates radiated interference, which can be used to dissipate radiated interference generated in the switching transistor and can also be used to further dissipate radiated interference amplified by the metal unit. This is advantageous in reducing the risk of interference and malfunction in each electronic device in the circuit, thereby improving the stability of the circuit during operation. Secondly, compared to the prior art technical solution of adding a shielding case, the added first capacitor of the present application has a small impact on the heat dissipation of the metal unit, i.e., the heat dissipation effect of the metal unit can be maintained. Furthermore, the volume of the added first capacitor is smaller than the volume of the added shielding case, which reduces the overall volume of the circuit and is advantageous in saving circuit design costs. [Brief explanation of the drawings]

[0025] In order to more clearly explain the technical solutions of the embodiments of the present application, the following will briefly describe the drawings that need to be used in the embodiments of the present application. It should be obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without paying any creative effort.

[0026] [Figure 1] 1 is a schematic diagram of the structure of a shield case and a MOS transistor disclosed in the prior art. [Figure 2] 1 is a schematic diagram of an application scenario disclosed in an embodiment of the present application; [Figure 3] 1 is a structural schematic diagram of a switch circuit disclosed in an embodiment of the present application; [Figure 4] FIG. 10 is a structural schematic diagram of a switch circuit disclosed in another embodiment of the present application; [Figure 5] FIG. 10 is a structural schematic diagram of a switch circuit disclosed in yet another embodiment of the present application. [Figure 6] FIG. 10 is a structural schematic diagram of a switch circuit disclosed in yet another embodiment of the present application. [Figure 7] FIG. 10 is a structural schematic diagram of a switch circuit disclosed in yet another embodiment of the present application. [Figure 8] FIG. 10 is a structural schematic diagram of a switch circuit disclosed in yet another embodiment of the present application. [Figure 9] FIG. 10 is a structural schematic diagram of a switch circuit disclosed in yet another embodiment of the present application. [Figure 10] 1 is a structural schematic diagram of a first gasket, a switching transistor, and a metal unit disclosed in an embodiment of the present application; [Figure 11] 1 is a schematic circuit diagram of a switch circuit disclosed in an embodiment of the present application; [Figure 12] 10 is a schematic diagram of a waveform of radiated interference when a first branch circuit is not added, according to an embodiment of the present application; [Figure 13] FIG. 10 is a schematic diagram of a waveform of radiated interference after adding a first branch circuit, according to an embodiment of the present application; [Figure 14] FIG. 10 is a schematic circuit diagram of a switch circuit disclosed in another embodiment of the present application;

[0027] In the drawing section, the drawings are not drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, the embodiments of the present application will be described in more detail with reference to the drawings and examples. The detailed description of the following examples and the drawings are used to exemplify the principles of the present application, but should not be used to limit the scope of the present application, i.e., the present application is not limited to the described examples.

[0029] It should be noted that in the description of this application, unless otherwise specified, "plurality" means two or more, and the orientation or positional relationship indicated by terms such as "up," "down," "left," "right," "inside," and "outside" does not indicate or imply that the depicted device or element must have a particular orientation or be configured and operated in a particular orientation. It is merely for the purpose of facilitating and simplifying the description of this application and should not be understood as a limitation of this application. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. "Perpendicular" does not mean perpendicular in the strict sense, but within a tolerance. "Parallel" does not mean parallel in the strict sense, but within a tolerance.

[0030] Any directions appearing in the following description refer to the directions shown in the drawings and are not intended to limit the specific structure of the present application. It should be further explained that in the description of the present application, unless otherwise clearly specified and limited, the terms "attached," "connected," and "connected" should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, or an integral connection, or may refer to a direct connection or an indirect connection via an intermediate medium. Those skilled in the art can understand the specific meanings of the above terms in the present application according to the specific circumstances.

[0031] Referring to FIG. 1, FIG. 1 is a structural schematic diagram of a shielding case and a MOS transistor disclosed in the prior art. As shown in FIG. 1, a heat sink 11 for heat dissipation is installed on a MOS transistor 10. In actual application processes, the switching frequency of a switching transistor is generally several tens of kHz or even several hundred kHz. That is, the dv / dt and di / dt of the switching transistor are large. Therefore, the switching transistor radiates and emits high-frequency radio interference during the switching process, and the resulting radiated interference is large and constantly increasing. In order to reduce the adverse effects of the radiated interference generated by the MOS transistor 10 on the normal operation of other electronic devices, a shielding case 1 is installed. 2 may cover the MOS transistor 10 and the heat sink 11 from top to bottom.

[0032] However, this method requires a large shielding case, which increases the volume of the entire circuit and the equipment including the circuit. Furthermore, as the number of MOS transistors 10 increases, the number of shielding cases must also increase accordingly, which increases the cost of the entire circuit and reduces its practicality. Furthermore, the additional shielding case may further reduce the heat dissipation effect, increasing the risk of damage to electronic devices such as the MOS transistors 10.

[0033] Based on this, an embodiment of the present application provides a switch circuit, which can form a discharge circuit by adding a branch circuit including a first capacitor to the switch circuit. The discharge circuit is used to discharge radiated interference generated in a switching transistor in the switch circuit, thereby maintaining heat dissipation effect, reducing radiated interference, and achieving a small volume.

[0034] The switch circuit disclosed in the embodiments of the present application may be used in, but is not limited to, a power supply device such as a switching power supply or a charging stand. A power supply system including a power supply device having the switch circuit disclosed in the present application may be used, which can provide a stable operating power source for the power supply system and is advantageous in improving the operating stability of the power supply system.

[0035] To facilitate understanding of the present application, we first introduce an application scenario to which the present application can be applied. As shown in Figure 2, the application scenario includes an electric vehicle 21, a charging station 22, and an interface 23. Here, the charging station 22 includes a power conversion module 221, a charging line 222, and a power line 223.

[0036] The power line 223 is connected to an external input power source (e.g., a commercial power source) via the interface 23 (e.g., a socket) to obtain an input voltage. The power conversion module 221 is provided with a switch circuit according to any one of the embodiments of the present application, thereby obtaining a stable voltage from the input voltage that can be used to supply power to a load. In this embodiment, the power conversion module 221 converts the obtained input voltage into a voltage that can be used to charge the electric vehicle 21. The voltage is transmitted to the electric vehicle 21 via the charging line 222 to charge the electric vehicle 21.

[0037] It should be noted that in this embodiment, the power supply device is a charging station, whereas in other embodiments, the power supply device may also be, but is not limited to, an on-board charger, an off-board charger, a switching power supply, etc.

[0038] Referring to Figure 3, Figure 3 illustrates the structure of a switch circuit disclosed in one embodiment of the present application. As shown in Figure 3, the switch circuit includes a metal unit 20, a first branch circuit 21, and at least one switching transistor. Here, 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 circuit 21 includes a first capacitor C1.

[0039] Here, the metal unit 20 may include a material that has a glossy finish, good electrical conductivity, thermal conductivity, and mechanical properties, and a positive temperature coefficient of resistance, such as aluminum or copper, but the embodiments of the present application are not limited thereto.

[0040] Specifically, the metal unit 20 may be disposed on the switching transistor Q1, switching transistor Q2, ... switching transistor Qn in the direction indicated by the arrow. In one embodiment, the metal unit 20 may be mounted on the switching transistor Q1, switching transistor Q2, ... switching transistor Qn in the manner shown in Fig. 1. The first branch circuit 21 is electrically connected between the switching transistor Q1, switching transistor Q2, ... switching transistor Qn and ground, and a first capacitor C1 can be used to achieve the purpose of dissipating radiated interference.

[0041] Here, the radiated interference is generated during the rapid switching process of the switching transistor, and the metal unit 20 increases the propagation volume of the radiated interference, which may further increase the radiated interference. The installation of the first capacitor C1 provides a relief circuit, which can effectively reduce the radiated interference, which is beneficial to reducing the risk of abnormal operation of the switch circuit due to radiated interference, and thereby improving the operation stability of the switch circuit.

[0042] Additionally, compared to the prior art technical solution of adding a shielding case, the first branch circuit 21 of the present application has a small impact on the heat dissipation of the metal unit 20, and can still maintain a good heat dissipation effect of the metal unit 20. On the other hand, the volume of the first branch circuit 21 is smaller than the volume of the added shielding case, which is advantageous for reducing the volume of the entire switch circuit and can reduce circuit design costs.

[0043] It should be noted that in this embodiment, the first branch circuit 21 is electrically connected between the switching transistor Q1, the switching transistor Q2, ... the switching transistor Qn and the ground. In another embodiment, as shown in Fig. 4, the first branch circuit 21 may be electrically connected between the metal unit 20 and the ground. In yet another embodiment, as shown in Fig. 5, the first branch circuit 21 may not only be electrically connected between the metal unit 20 and the ground, but also be electrically connected between the switching transistor Q1, the switching transistor Q2, ... the switching transistor Qn and the ground. Here, in the embodiments shown in Fig. 3, 4, or 5, the first capacitor C1 can be used to achieve the purpose of dissipating radiated interference.

[0044] Furthermore, each switching transistor may be a switching element such as a metal oxide semiconductor field effect transistor or an insulated gate bipolar transistor, and the embodiments of the present application are not limited thereto.

[0045] In one embodiment, the first branch circuit 21 further includes a first resistor, where the first resistor is connected in series with the first capacitor. The structure shown in FIG. 3 will be taken as an example to further include the first resistor.

[0046] 6, the first branch circuit 21 includes a first resistor R1 and a first capacitor C1 connected in series, where the positions of the first resistor R1 and the first capacitor C1 can be interchanged, i.e., the switching transistor Q1, the switching transistor Q2, ... the switching transistor Qn can be sequentially connected to the first capacitor C1 and the first resistor R1, or the switching transistor Q1, the switching transistor Q2, ... the switching transistor Qn can be sequentially connected to the first resistor R1 and the first capacitor C1.

[0047] The addition of the first resistor R1 is advantageous in dissipating more radiated interference faster, and further improving the stability during operation of the switch circuit.

[0048] As can be understood, the first branch circuit 21 according to this embodiment can be applied to the circuit structure shown in FIG. 4 or FIG. 5, which is within the scope of easy understanding by those skilled in the art, and will not be further described here.

[0049] In one embodiment, the first branch circuit 21 further includes a second capacitor, and the second capacitor is connected in series with the first capacitor. The structure shown in Figure 3 will be described as an example, further including a second capacitor.

[0050] As shown in FIG. 7, the first branch circuit 21 includes a second capacitor C2 and a first capacitor C1 connected in series.

[0051] In one embodiment, the capacitances of the first capacitor C1 and the second capacitor C2 may be set to be equal to each other so that the total capacitance of the circuit formed by connecting the first capacitor C1 and the second capacitor C2 in series is equal to the capacitance of the first capacitor C1. Maintaining a constant capacitance value can maintain a low capacitance value, which is advantageous in reducing abnormalities such as short circuits in the switch circuit caused by excessive capacitance. On the other hand, connecting multiple capacitors in series can increase the withstand voltage of the first branch circuit 21, allowing it to be used in multiple application scenarios with different voltages, which is advantageous in improving the practicality of the switch circuit.

[0052] As can be understood, the first branch circuit 21 according to this embodiment can also be applied to the circuit structure shown in FIG. 4 or FIG. 5, which is within the scope of easy understanding by those skilled in the art, and will not be further described here.

[0053] In addition, in the embodiments of the present application, the contents related to the first branch circuit 21 may be used alone or in combination, and the embodiments of the present application are not limited thereto. For example, in one embodiment, the structures of the first branch circuit 21 shown in Figures 6 and 7 may be combined, that is, in this embodiment, the first branch circuit 21 includes a first capacitor C1, a second capacitor C2, and a first resistor R1 connected in series.

[0054] In one embodiment, in the circuit structure shown in FIG. 3, n may be set to a positive integer greater than 1, ie, in this case, the switch circuit includes at least two switching transistors.

[0055] 8, the metal unit 20 includes a metal subunit M1, a metal subunit M2, and a metal subunit Mn. Here, the metal subunit M1 is disposed on the switching transistor Q1, the metal subunit M2 is disposed on the switching transistor Q2, and the metal subunit Mn is disposed on the switching transistor Qn. That is, the metal subunits and the switching transistors correspond one-to-one, and one metal subunit is disposed on each switching transistor.

[0056] In this embodiment, the first branch circuit 21 must include a first sub-branch circuit L1, a first sub-branch circuit L2, ..., a first sub-branch circuit Ln, and the first sub-branch circuits and the metal subunits correspond one-to-one. In this case, the first sub-branch circuit L1 is electrically connected between the metal subunit M1 and the ground, the first sub-branch circuit L2 is electrically connected between the metal subunit M2 and the ground, ..., the first sub-branch circuit Ln is electrically connected between the metal subunit Mn and the ground. That is, a first sub-branch circuit is connected between each metal subunit and the ground.

[0057] As can be seen, the structure of any one of the first sub-branch circuits may be the same as the structure of the first branch circuit 21 in Figure 3, Figure 4, Figure 5, Figure 6 or Figure 7. This may allow the radiation interference amplified by each metal subunit to escape, and the radiation interference can be more effectively escaped, which is advantageous in significantly reducing the radiation interference and improving the stability of the circuit operation.

[0058] In this embodiment, the number of metal subunits is equal to the number of switching transistors. In other embodiments, the number of metal subunits may not be equal to the number of switching transistors. For example, multiple switching transistors may share one metal subunit. In this case, the first sub-branch circuit may be installed corresponding to the number of metal subunits, and the radiated interference amplified by each metal subunit can be similarly eliminated.

[0059] 9, the switch circuit includes at least two bridge arms, namely, bridge arm A1, bridge arm A2, ... bridge arm Ak, where k is a positive integer greater than 1. Here, bridge arm A1 includes switching transistor Q1 and switching transistor Q2, bridge arm A2 includes switching transistor Q3 and switching transistor Q4, ... bridge arm Ak includes switching transistor Qn-1 and switching transistor Qn, i.e., each bridge arm includes two switching transistors.

[0060] Furthermore, in this embodiment, the first branch circuit 21 includes second sub-branch circuits that correspond one-to-one to the bridge arms. That is, the first branch circuit 21 includes second sub-branch circuits L11, L12, ..., L1k. Each second sub-branch circuit is electrically connected between a bridge arm and ground. That is, the second sub-branch circuit L11 is electrically connected between the bridge arm A1 and ground, the second sub-branch circuit L12 is electrically connected between the bridge arm A2 and ground, ..., the second sub-branch circuit L1k is electrically connected between the bridge arm Ak and ground.

[0061] It can be understood that the structure of any one of the second sub-branch circuits may be the same as the structure of the first branch circuit 21 in Figure 3, Figure 4, Figure 5, Figure 6 or Figure 7. This can dissipate the radiation interference generated in each bridge arm, which can more effectively dissipate the radiation interference and is advantageous to improving the stability of the circuit operation.

[0062] In one embodiment, the switch circuit further includes a first gasket disposed between the switching transistor and the metal unit, and the first gasket may be used to isolate the switching transistor from the metal unit to reduce the risk of electric shock caused by the voltage or current in the switching transistor being conducted through the metal unit.

[0063] Take the switching transistor Q1 as an example, where the metal unit is a heat sink. As shown in FIG. 10 , a first gasket 22 is installed between the switching transistor Q1 and the metal unit 20. Because heat generation due to a series of losses, such as turn-on loss, turn-off loss, and conduction loss, is unavoidable in the switching transistor Q1, it is necessary to install the metal unit 20 (i.e., a heat sink) on the switching transistor Q1 to dissipate heat and extend the service life of the switching transistor Q1. Furthermore, since voltage or current is applied to the switching transistor Q1, the first gasket 22 may be installed between the switching transistor Q1 and the metal unit 20. The first gasket 22 should be made of an insulating material and have thermal conductivity so that the heat generated by the switching transistor Q1 can be transferred to the metal unit 20, thereby completing the heat dissipation process of the switching transistor Q1.

[0064] In one embodiment, the capacitance range of the first branch circuit 21 is 1 nF-10 nF, where nF represents nanofarads, which are units of capacitance. For example, as shown in FIG. 3, when the first branch circuit 21 includes a first capacitor C1, the capacitance range of the first capacitor C1 is 1 nF-10 nF. For example, as shown in FIG. 7, when the first branch circuit 21 includes a first capacitor C1 and a second capacitor C2, the total capacitance range of the first capacitor C1 and the second capacitor C2 is 1 nF-10 nF.

[0065] When the capacitance of the first branch circuit 21 is in the range of 1 nF to 10 nF, the first branch circuit 21 can provide a good dissipation effect against radiated interference. Furthermore, within this range, the dissipation effect improves as the capacitance increases.

[0066] In one embodiment, the switch circuit further includes a filtering sub-circuit, the filtering sub-circuit connected to the AC power supply and the switching transistor, respectively, for filtering out differential mode interference and common mode interference in the AC power supply, where common mode interference is defined as an undesired potential difference between any current-carrying conductor and a reference ground, and differential mode interference is defined as an undesired potential difference between any two current-carrying conductors.

[0067] Specifically, the circuit structure of an exemplary switch circuit shown in FIG. 11 will be taken as an example. As shown in FIG. 11, the switch circuit includes a metal unit 20, a first branch circuit 21, and a filtering branch circuit 23. The switch circuit further includes a switching transistor Q1, a switching transistor Q2, a switching transistor Qn, and a first gasket, where the first gasket may be equivalent to a parasitic capacitor C11 with a small capacitance value. In addition, in this embodiment, the first branch circuit 21 includes only the first capacitor C1 as an example. The filtering branch circuit 2 3is electrically connected between an AC power source AC and each switching transistor, a parasitic capacitor C11 is electrically connected between each switching transistor and the metal unit 20, and a first capacitor C1 is electrically connected between the metal unit 20 and earth (which may be the housing of a device including the switch circuit).

[0068] Specifically, the first capacitor C1 can provide a discharge circuit for the radiated interference generated in each switching transistor, which sequentially includes the metal unit 20, the first capacitor C1, the filtering branch circuit 23, each switching transistor, the parasitic capacitor C11, and the metal unit 20. As a result, the radiated interference passing through the metal unit 20 is dissipated in the discharge circuit, thereby significantly reducing the radiated interference value.

[0069] 12 and 13, Fig. 12 shows the radiated interference without adding the first branch circuit 21, and Fig. 13 shows the radiated interference after adding the first branch circuit 21. Here, waveforms B1 and B2 are waveforms of the radiated interference, and waveform B0 is the safety threshold of the radiated interference. Only when the radiated interference is smaller than the safety threshold can the impact of the radiated interference on other electronic devices be approximately negligible.

[0070] Specifically, as shown in Figure 12, when the first branch circuit 21 was not added to the switch circuit, waveform B1 exceeded waveform B0 in the frequency band from 35 MHz to 50 MHz, i.e., the radiated interference exceeded the safety threshold. Furthermore, as shown in Figure 13, after the first branch circuit 21 was added, most of waveform B2 was smaller than waveform B0 in the frequency band from 35 MHz to 50 MHz, i.e., most of the radiated interference was reduced to a value below the safety threshold. In particular, when the frequency was around 40 MHz, the radiated interference was reduced by about 10 dB, which was a more significant effect.

[0071] As can be seen, adding the first branch circuit 21 can significantly reduce radiated interference and is beneficial for protecting the electronic devices in the switch circuit, thereby extending their service life. At the same time, the operational stability of the switch circuit is also improved. The added first capacitor C1 is electrically connected between the metal unit 20 and ground, reducing the probability of the first capacitor C1 being short-circuited, allowing the first capacitor C1 to play a protective role.

[0072] As can be seen, in this embodiment, the first branch circuit 21 is electrically connected between the metal unit 20 and the ground. In other embodiments, the first branch circuit 21 may be electrically connected between each switching transistor and the ground, and the specific implementation has been described in the above embodiment, so will not be further described here.

[0073] In one embodiment, the filtering sub-circuit 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 inductance T1, and a magnetizing inductance T2. Here, the first safety capacitor CY1 is electrically connected between a first end of the alternating current power source AC and ground, the second safety capacitor CY2 is electrically connected between a second end of the alternating current power source AC and ground, the third safety capacitor CX1 is electrically connected between the first end of the alternating current power source AC and a second end of the alternating current power source AC, a first identically named end of the common-mode inductance T1 is electrically connected to the first end of the alternating current power source AC, a second identically named end of the common-mode inductance T1 is electrically connected to the second end of the alternating current power source AC, a first differently named end of the common-mode inductance T1 is connected to a first end of the fourth safety capacitor CX2, and a second differently named end of the common-mode inductance T1 is connected to a second end of the fourth safety capacitor CX2, the first end of the fourth safety capacitor CX2 is further electrically connected to each switching transistor via the magnetizing inductance T2, and the second end of the fourth safety capacitor CX2 is electrically connected to each switching transistor.

[0074] Specifically, the first safety capacitor CY1 and the second safety capacitor CY2 are for filtering out differential mode interference. The third safety capacitor CX1 and the fourth safety capacitor CX2 are for filtering out common mode interference. The common mode inductance T1 is for filtering out common mode radio wave interference in the signal line, but may also be for suppressing the device itself from emitting radio wave interference to avoid affecting the normal operation of other electronic devices in the same electromagnetic environment. The magnetizing inductance T2 is for achieving voltage step-up or step-down.

[0075] In this embodiment, the safety capacitor refers to a safety capacitor that will not cause electric shock or endanger personal safety after the capacitor fails. Therefore, selecting a safety capacitor for each capacitor can improve safety during operation of the switch circuit. Of course, other types of capacitors may be used in other embodiments, and the embodiments of this application are not limited thereto. Furthermore, this embodiment can filter out differential mode interference and common mode interference in the AC power supply, thereby providing a stable AC power supply for subsequent circuits and improving the stability of the circuit during operation.

[0076] It should be noted that the circuit structure of the switch circuit shown in Figure 11 is merely an example, and the switch circuit may have more or fewer components than those shown in the figure, may combine two or more components, or may have a different component arrangement, and the embodiments of the present application are not limited thereto. For example, in one embodiment, the switch circuit may be a resonant bidirectional full-bridge DC / DC conversion circuit. Also, for example, in another embodiment, the switch circuit may further be a phase-shift full-bridge circuit.

[0077] Here, the resonant bidirectional full-bridge DC / DC conversion circuit may be as shown in Fig. 14. In this circuit, a switching transistor S141, a switching transistor S142, a switching transistor S143, a switching transistor S144, a switching transistor S145, a switching transistor S146, a switching transistor S147, a switching transistor S148, a switching transistor S149, a switching transistor S200, a switching transistor S201, a switching transistor S202, a switching transistor S203, a switching transistor S204, a switching transistor S205, a switching transistor S206, a switching transistor S207, a switching transistor S208, a switching transistor S209, a switching transistor S210, a switching transistor S211, a switching transistor S212, a switching transistor S213, a switching transistor S214, a switching transistor S215, a switching transistor S216, a switching transistor S217, a switching transistor S218, a switching transistor S219, a switching transistor S220, a switching transistor S221, a switching transistor S222, a switching transistor S223, a switching transistor S224, a switching transistor S225, a switching transistor S226, a switching transistor S227, a switching transistor S228, a switching transistor S229, a switching transistor S230, a switching transistor S231, a switching transistor S232, a switching transistor S233, a switching transistor S234, a switching transistor S235, a switching transistor S236, a switching transistor S237, a switching transistor S238, a switching transistor S239, a switching transistor S240, a switching transistor S241, a switching transistor S242, a switching transistor S243, a switching transistor S244, a switching transistor S245, a switching transistor S246, a switching transistor S247, a switching transistor S248, a switching transistor S249, a switching transistor S250, 7 and switching transistor S148 may each be provided with a metal unit. Furthermore, a first branch circuit may be provided between each switching transistor and ground, and / or a first branch circuit may be provided between the metal unit and ground, so as to dissipate radiated interference generated in each switching transistor. The specific implementation process has been described in the above embodiment, and will not be further described here.

[0078] An embodiment of the present application provides a power supply device, the power supply device including the switch circuit of any one of the above embodiments, wherein the power supply device may be a device that obtains energy from a power grid and provides electrical energy for one or more loads after conversion.

[0079] In one embodiment, the power supply device is a switching power supply or a charging station, where the switching power supply or charging station may take an input voltage from a utility power source and convert the input voltage to a voltage usable by other devices.

[0080] Although the present application has been described with reference to preferred embodiments, various improvements may be made thereto and equivalents may be substituted for the elements therein without departing from the scope of the present application. In particular, as long as there is no structural contradiction, any of the technical features recited in each embodiment may be combined in any manner. The present 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 switch circuit, at least one switching transistor; a metal unit provided on the switching transistor; a first branch circuit electrically connected between the metal unit and ground and between the switching transistor and ground; Here, the first branch circuit includes a first capacitor for dissipating radiated interference.

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

3. the first branch circuit further includes a second capacitor; 2. The switch circuit according to claim 1, wherein the first capacitor and the second capacitor are connected in series.

4. the switch circuit includes at least two switching transistors; The metal unit includes metal subunits that correspond one-to-one to the at least two switching transistors, and each of the at least two switching transistors is provided with one metal subunit; 2. The switch circuit of claim 1, wherein the first branch circuit includes first sub-branch circuits that correspond one-to-one to the metal subunits, and wherein any one of the first sub-branch circuits is electrically connected between the metal subunit and ground.

5. the at least one switching transistor includes at least two bridge arms connected in parallel, wherein the bridge arm includes two switching transistors connected in series; 2. The switch circuit according to claim 1, wherein the first branch circuit includes second sub-branch circuits that correspond one-to-one to the bridge arms, and wherein any one of the second sub-branch circuits is electrically connected between one of the bridge arms and ground.

6. the switch circuit further includes a first gasket; The switch circuit according to claim 1 , wherein the first gasket is provided between the switching transistor and the metal unit.

7. 7. The switch circuit according to claim 1, wherein the capacitance range of the first capacitor is 1 nF to 10 nF, where nF represents nanofarad, which is a unit of capacitance.

8. the switch circuit further includes a filtering branch circuit; 7. The switch circuit according to claim 1, wherein the filtering branch circuits are connected to an AC power supply and to the switching transistor, respectively, and the filtering branch circuits are for filtering out differential mode interference and common mode interference in the AC power supply.

9. A power supply device comprising a switch circuit according to any one of claims 1 to 8.

10. 10. The power supply device of claim 9, wherein the power supply device is a switching power supply or a charging stand.

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