Filter and power supply system

Abstract

A filter and a power supply system. The filter comprises a differential mode signal suppression unit which is connected with a phase line and is used for filtering a differential mode signal; the high-impedance common-mode filtering unit is connected with the phase line and is used for inhibiting interference of the high-frequency common-mode signal on the power supply; the low-impedance common-mode filtering unit is connected with the phase line and the protection conductor and is used for conducting a high-frequency common-mode signal to the protection conductor; and the switching unit is connected with the protection conductor and is used for disconnecting a loop between the low-impedance common-mode filtering unit and the protection conductor or conducting the loop between the low-impedance common-mode filtering unit and the protection conductor. By adopting the scheme, the cost of a power supply system can be reduced, and large-scale and unified production of the filter is facilitated.

Description

[0001] This application claims the priority of the Chinese patent application filed with the China Patent Office on October 10, 2023, with application number 202311309957.X and invention name “Filter and Power Supply System”, the entire contents of which are incorporated by reference in this application. Technical Field

[0002] The present invention relates to the technical field of power supply, and in particular to a filter and a power supply system. Background Art

[0003] The power supply system refers to the system composed of the power supply system and the transmission and distribution system that generates electrical energy and supplies and transmits it to electrical equipment. The power supply system can be roughly divided into three types: TN, IT, and TT.

[0004] Among them, in the TN system, the neutral point of the power supply is grounded, and the metal shell of the electrical equipment is grounded by connecting to the neutral point of the power supply. In the IT system, the neutral point of the power supply is not grounded, and the metal shell of the electrical equipment is directly grounded. In the TT system, the neutral point of the power supply is grounded, and the metal shell of the electrical equipment is directly grounded.

[0005] The existing TN system and IT system use different filters for filtering to avoid electromagnetic interference, which increases the cost of the power supply system and is not conducive to the large-scale and unified production of filters. Summary of the invention

[0006] The problem to be solved by the present invention is to reduce the cost of the power supply system and facilitate the large-scale and unified production of filters.

[0007] In order to solve the above problem, an embodiment of the present invention provides a filter, wherein the filter comprises:

[0008] A differential mode signal suppression unit is connected to the phase line and is used to filter the differential mode signal;

[0009] A high impedance common mode filter unit is connected to the phase line to suppress the interference of high frequency common mode signals on the power supply;

[0010] A low impedance common mode filter unit is connected to the phase line and the protection conductor and is used to conduct high frequency common mode signals to the protection conductor;

[0011] A switching unit is connected to the protection conductor and is used to disconnect the loop between the low-impedance common-mode filtering unit and the protection conductor, or to connect the loop between the low-impedance common-mode filtering unit and the protection conductor.

[0012] Optionally, the filter includes: a protection conductor power supply terminal and a protection conductor load terminal; the switching unit includes: a first switch circuit located between the protection conductor power supply terminal and the protection conductor load terminal.

[0013] Optionally, the first switch circuit includes: a first switch.

[0014] Optionally, the switching unit further includes:

[0015] The magnetic flux suppression circuit is connected to the first switch circuit and is used to suppress the increase of the magnetic flux of the high impedance common mode filter unit after the loop between the low impedance common mode filter unit and the protection conductor is disconnected.

[0016] Optionally, the magnetic flux suppression circuit includes: a second switch and a short-circuiting coil, and two ends of the short-circuiting coil are connected to the second switch.

[0017] Optionally, when the first switching circuit connects the loop between the low-impedance common-mode filtering unit and the protection conductor, the second switch disconnects the short-circuit coil; when the first switching circuit disconnects the loop between the low-impedance common-mode filtering unit and the protection conductor, the second switch short-circuits the short-circuit coil.

[0018] Optionally, the high-impedance common-mode filtering unit includes: a magnetic ring, and a first winding, a second winding, and a third winding wound on the magnetic ring, wherein the first winding to the third winding are respectively connected to different phase lines.

[0019] Optionally, the short-circuit coil is wound around the magnetic ring.

[0020] Optionally, the short-circuit coil is located between any two phase windings.

[0021] Optionally, the differential mode signal suppression unit is a differential mode capacitor group.

[0022] Optionally, the low-impedance common-mode filtering unit is a common-mode capacitor group.

[0023] An embodiment of the present invention further provides a power supply system, the system comprising:

[0024] power supply;

[0025] A filter of any of the above;

[0026] and load;

[0027] One end of the filter is connected to the phase line output end of the power supply, and the other end is connected to the load.

[0028] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0029] By applying the solution of the present invention, a switching unit is provided, and the switching unit can disconnect the loop between the low-impedance common-mode filter unit and the protection conductor, and can also connect the loop between the low-impedance common-mode filter unit and the protection conductor. When the loop between the low-impedance common-mode filter unit and the protection conductor is disconnected, the entire filter does not need to filter out the electromagnetic interference of high-frequency common-mode signals, and is thus suitable for use in IT systems. When the loop between the low-impedance common-mode filter unit and the protection conductor is connected, the entire filter needs to filter out the electromagnetic interference of common-mode signals and differential-mode signals at the same time, and is thus suitable for use in TN systems. In this way, there is no need to provide a separate filter for the IT system or the TN system, thereby reducing the cost of the power supply system and facilitating the large-scale and unified production of filters.

[0030] Furthermore, by providing a magnetic flux suppression circuit, after the loop between the low-impedance common-mode filter unit and the protective conductor is disconnected, the magnetic flux saturation of the high-impedance common-mode filter unit can be suppressed, thereby avoiding the phenomenon of overheating or even burning of the high-impedance common-mode filter unit due to magnetic flux saturation, thereby improving the safety of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the structure of a filter in an embodiment of the present invention;

[0032] Figure 2 is a schematic diagram of the structure of another filter in an embodiment of the present invention;

[0033] Figure 3 is a top view of a common mode coil assembly in an embodiment of the present invention;

[0034] Figure 4 4 is a side view of a common mode coil assembly in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In the TN system, the metal casing of the electrical equipment is grounded by connecting to the neutral point of the power supply, that is, there is a ground loop. Therefore, common-mode electromagnetic interference will have a greater impact on the TN system. The filter used in the TN system needs to filter out both differential-mode and common-mode high-frequency interference.

[0036] In IT systems, the metal casing of electrical equipment is directly grounded, that is, there is no ground loop, and no common-mode electromagnetic interference is generated to the IT system. At this time, the filter used in the IT system only needs to filter out the high-frequency interference of the differential mode.

[0037] The existing TN system and IT system use different filters for filtering to avoid electromagnetic interference, which increases the cost of the power supply system and is not conducive to the large-scale and unified production of filters.

[0038] In view of this problem, the present invention provides a filter, in which a switching unit is provided, and the switching unit can disconnect the loop between the low-impedance common-mode filter unit and the protection conductor, and can also connect the loop between the low-impedance common-mode filter unit and the protection conductor. When the loop between the low-impedance common-mode filter unit and the protection conductor is disconnected, the entire filter does not need to filter out the electromagnetic interference of high-frequency common-mode signals, so that it is suitable for application in IT systems. When the loop between the low-impedance common-mode filter unit and the protection conductor is connected, the entire filter needs to filter out the electromagnetic interference of common-mode signals and differential-mode signals at the same time, so that it is suitable for application in TN systems. In this way, there is no need to set up a separate filter for the IT system or the TN system, so that the cost of the power supply system can be reduced, and it is conducive to the large-scale and unified production of filters.

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0040] Reference Figure 1 The embodiment of the present invention provides a filter 10, which may include: a differential signal suppression unit 11, a high impedance common mode filter unit 12, a low impedance common mode filter unit 13 and a switching unit 14. Wherein:

[0041] The differential mode signal suppression unit 11 is connected to the phase line and is used to filter the differential mode signal;

[0042] The high impedance common mode filter unit 12 is connected to the phase line and is used to suppress the interference of high frequency common mode signals on the power supply;

[0043] The low impedance common mode filter unit 13 is connected to the phase line and the protection conductor, and is used to conduct the high frequency common mode signal to the protection conductor;

[0044] The switching unit 14 is connected to the protection conductor and is used to disconnect the loop between the low impedance common mode filtering unit 13 and the protection conductor, or to connect the loop between the low impedance common mode filtering unit 13 and the protection conductor.

[0045] In a specific implementation, the filter 10 is located between the power supply 20 and the load 30. During the transmission process, the power supply signal output by the power supply 20 usually receives interference from the external environment, such as electromagnetic interference. These interferences will generate common-mode signals and differential-mode signals, thereby affecting the transmission quality of the power supply signal. Among them, the interference caused by the differential-mode signal on the transmission of the power supply signal is called differential-mode interference, which belongs to the noise between the phase lines. The interference caused by the common-mode signal on the transmission of the power supply signal is called common-mode interference, which belongs to the noise between the phase line and the earth. For this reason, it is necessary to set a filter 10 between the power supply 20 and the load 30 to filter out the corresponding interference signals and provide stability and reliability of signal transmission.

[0046] In a specific implementation, the number of phase lines is usually three, namely the first phase line, the second phase line and the third phase line. The filter 10 can be a three-phase filter, and has a first phase line input terminal L1, a first phase line output terminal L1', a second phase line input terminal L2, a second phase line output terminal L2', a third phase line input terminal L3 and a third phase line output terminal L3'. The first phase line input terminal L1 is connected to the first phase line of the power supply 20 to access the power supply signal transmitted on the first phase line and filter it. The second phase line input terminal L2 is connected to the second phase line of the power supply 20 to access the power supply signal transmitted on the second phase line and filter it. The third phase line input terminal L3 is connected to the third phase line of the power supply 20 to access the power supply signal transmitted on the third phase line and filter it.

[0047] In a specific implementation, the differential mode signal suppression unit 11 may be a differential mode capacitor group. The differential mode capacitor group is located between phase lines.

[0048] Specifically, refer to Figure 2 , the differential signal suppression unit 11 may include: a first differential capacitor Cf1, a second differential capacitor Cf2, and a third differential capacitor Cf3. One end of the first differential capacitor Cf1 may be connected to the first phase line input terminal L1 and the second phase line input terminal L2, thereby connecting to the first phase line and the second phase line of the power supply. One end of the second differential capacitor Cf2 may be connected to the second phase line input terminal L2 and the third phase line input terminal L3, thereby connecting to the second phase line and the third phase line of the power supply. One end of the third differential capacitor Cf3 may be connected to the first phase line input terminal L1 and the third phase line input terminal L3, thereby connecting to the first phase line and the third phase line of the power supply.

[0049] Since capacitors can store electrical energy, when the voltage across the capacitor changes, the capacitor will release or absorb charge to achieve signal transmission and filtering. Therefore, when a differential signal is generated on the phase line, the differential signal will be introduced into the differential capacitor, thereby using this characteristic of the capacitor to filter out the differential signal.

[0050] In a specific implementation, the low impedance common mode filter unit 13 can be a common mode capacitor group. One end of the common mode capacitor group is connected to the phase line, and the other end is connected to the protection conductor. The protection conductor, also known as the protection line, is a wire connected to the earth through a deep buried electrode and short-circuited, also known as the ground wire, which is a conductor used to ground the metal casing of the electrical equipment.

[0051] Specifically, refer to Figure 2 , the common-mode capacitor group may include: a first common-mode capacitor Cs1, a second common-mode capacitor Cs2 and a third common-mode capacitor Cs3. One end of the first common-mode capacitor Cs1 is connected to the first phase line output terminal L1', and the other end is connected to the protection conductor load terminal PE'. One end of the second common-mode capacitor Cs2 is connected to the second phase line output terminal L2', and the other end is connected to the protection conductor load terminal PE'. One end of the third common-mode capacitor Cs3 is connected to the third phase line output terminal L3', and the other end is connected to the protection conductor load terminal PE'.

[0052] Since capacitors can store electrical energy, when the voltage across the two poles of the capacitor changes, the capacitor will release or absorb charge to achieve signal transmission and filtering. Therefore, when a common-mode signal is generated on the phase line, the common-mode signal will be introduced into the common-mode capacitor, thereby using this characteristic of the capacitor to filter out the common-mode signal.

[0053] In a specific implementation, the high impedance common mode filter unit 12 may be a common mode coil group, one end of which is connected to the phase line, and the other end of which is connected to the protective conductor at the same potential.

[0054] Figure 3 It is a top view of the common mode coil assembly. Figure 4 This is a side view of the common mode coil assembly. Figures 2 to 4 Specifically, the common mode coil group may include: a magnetic ring 121 and a first winding P1, a second winding P2 and a third winding P3 wound on the magnetic ring 121. The first end p1a of the first winding P1 is connected to the first phase line input terminal L1, and the second end P1b is connected to the first phase line output terminal L1'. The first end p2a of the second winding P2 is connected to the second phase line input terminal L2, and the second end P2b is connected to the second phase line output terminal L2'. The first end p3a of the third winding P3 is connected to the third phase line input terminal L3, and the second end P3b is connected to the third phase line output terminal L3'. An insulating baffle is provided between adjacent windings of the common mode coil group.

[0055] When a common-mode signal flows through the winding, the magnetic flux in the magnetic ring 121 will be superimposed on each other, thereby increasing the inductance of the common-mode coil group, thereby suppressing the common-mode signal. When a differential-mode signal flows through the winding, the magnetic flux in the magnetic ring 121 cancels each other out, and there is almost no inductance, so the differential-mode signal can pass without attenuation. Therefore, the common-mode coil group can suppress common-mode interference in the transmission line.

[0056] In a specific implementation, the switching unit 14 is connected to the protection conductor, which can not only disconnect the loop between the low-impedance common-mode filter unit 13 and the protection conductor, but also conduct the loop between the low-impedance common-mode filter unit 13 and the protection conductor. When the loop between the low-impedance common-mode filter unit 13 and the protection conductor is disconnected, it is equivalent to the filter 10 without a ground loop, so it is suitable for IT systems. When the loop between the low-impedance common-mode filter unit 13 and the protection conductor is conducted, it is equivalent to the filter 10 with a ground loop, so it is suitable for TN systems.

[0057] In a specific implementation, the structure of the switching unit 14 is not limited.

[0058] In one embodiment, referring to Figure 2 , the switching unit may include a first switch circuit 141. The first switch circuit 141 is located between the protection conductor power supply terminal PE and the protection conductor load terminal PE'.

[0059] In a specific implementation, the first switching circuit 141 can be a switching device that can implement switching, or a combination of multiple switching devices that can implement switching. It is not limited to a specific form of switching device, as long as it can disconnect or conduct the loop between the low-impedance common-mode filtering unit 13 and the protective conductor.

[0060] In one embodiment of the present invention, referring to Figure 2 , the first switch circuit 141 may include: a first switch s1, one end of the first switch s1 is connected to the protection conductor power supply terminal PE, and the other end is connected to the protection conductor load terminal PE'. When the first switch s1 is disconnected, the low impedance common mode filter unit 13 cannot be connected to the protection conductor of the power supply, and thus cannot be grounded. When the first switch s1 is closed, the low impedance common mode filter unit 13 can be connected to the protection conductor of the power supply, thereby achieving grounding.

[0061] In practical applications, once the first switch s1 is operated by mistake, that is, the first switch s1 is disconnected when applied to the TN system, the high-frequency common-mode interference will lose the low-resistance ground capacitance bypass channel, and the common-mode signal can only be suppressed by the common-mode coil group. At this time, the magnetic flux of the common-mode coil group will increase geometrically and it is very easy to saturate. When saturated, the temperature of the magnetic ring of the common-mode coil group will rise sharply, causing the insulation material in the common-mode coil group to fail at high temperature, and even burn due to overheating or insulation failure, which poses certain safety hazards.

[0062] Therefore, in one embodiment of the present invention, in order to improve the safety of the filter, Figure 2The switching unit may further include: a magnetic flux suppression circuit 142. The magnetic flux suppression circuit 142 may be connected to the first switching circuit 141, and is used to suppress the increase of the magnetic flux of the high impedance common mode filter unit 12 after the loop between the low impedance common mode filter unit 13 and the protection conductor is disconnected.

[0063] By suppressing the saturation of the magnetic flux in the high-impedance common-mode filter unit 12, excessive temperature rise of the filter can be avoided, thereby reducing the potential safety hazards caused thereby.

[0064] In a specific implementation, the magnetic flux suppression circuit 142 can be implemented using a variety of structures, which are not limited here.

[0065] In one embodiment of the present invention, referring to Figure 2 , the magnetic flux suppression circuit 142 may include: a second switch s2 and a short-circuit coil P4, wherein both ends of the short-circuit coil P4 are connected to the second switch s2. Figure 3 and Figure 4 The first end P4a of the short-circuit coil P4 is connected to one end of the second switch. The second end P4a of the short-circuit coil P4 is connected to the other end of the second switch.

[0066] When the first switch circuit 141 connects the loop between the low impedance common mode filter unit 13 and the protection conductor, the second switch s2 disconnects the shorting coil P4. When the first switch circuit 141 disconnects the loop between the low impedance common mode filter unit 13 and the protection conductor, the second switch s2 shorts the shorting coil P4.

[0067] Since there is mutual inductance between the short-circuited coil P4 and the windings in the common-mode coil group, when the second switch s2 is closed, the short-circuited coil P4 is short-circuited, and the magnetic flux generated by the short-circuit current flowing through the short-circuited coil P4 will offset the magnetic flux generated by the original common-mode coil group, thereby reducing the magnetic flux of the common-mode coil group and reducing the inductance of the common-mode coil group, thereby achieving the purpose of suppressing the magnetic flux.

[0068] In a specific implementation, the short-circuit coil P4 is wound on the same magnetic core as the high-impedance common-mode filter unit, and when the short-circuit coil P4 is short-circuited, the magnetic flux in the common-mode coil group is suppressed to avoid saturation.

[0069] In a specific implementation, the position of the short-circuit coil P4 wound on the magnetic ring 121 is different, and the effect of suppressing the magnetic flux is also different. Figure 3 and Figure 4 When the short-circuit coil P4 is wound on the magnetic ring 121, it can be wound on the magnetic ring area between the second winding P2 and the third winding P3.

[0070] In a specific implementation, the first switch s1 and the second switch s2 may be mechanically linked switches. Specifically, when the first switch s1 is closed, the second switch s2 is opened. When the first switch s1 is opened, the second switch s2 is closed.

[0071] When used in a TN system, the first switch s1 conducts the loop interference between the low-impedance common-mode filter unit 13 and the protective conductor to conduct the high-frequency common-mode signal to the protective conductor. When used in an IT system, the first switch s1 disconnects the loop between the low-impedance common-mode filter unit 13 and the protective conductor. At the same time, the first switch s1 is mechanically linked with the second switch s2. When the loop between the low-impedance common-mode filter unit 13 and the protective conductor is connected, the second switch s2 disconnects the short-circuit coil P4. When the loop between the low-impedance common-mode filter unit 13 and the protective conductor is disconnected, the second switch s2 connects the short-circuit coil P4 loop. When the short-circuit coil P4 is disconnected, the common-mode coil group works normally. When the short-circuit coil P4 is connected, the magnetic flux saturation can be suppressed to prevent the magnetic ring from overheating.

[0072] From the above content, it can be known that the filter in the embodiment of the present invention can be applied not only to IT system but also to TN system. Moreover, when applied to TN system, even if the ground loop is disconnected by mistake, the filter can still work safely and will not be damaged due to excessive temperature rise.

[0073] The embodiment of the present invention further provides a power supply system, specifically Figure 1 As shown, the power supply system may include: a power supply 20, a filter 10 and a load 30. One end of the filter 10 is connected to the phase line output end of the power supply 20, and the other end is connected to the load 30.

[0074] Since the filter 10 can be applied to both IT systems and TN systems, the power supply cost can be effectively reduced. In addition, the use safety of the filter 10 can also be improved.

[0075] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A filter, characterized in that: include: A differential mode signal suppression unit is connected to the phase line and is used to filter the differential mode signal; A high impedance common mode filter unit is connected to the phase line to suppress the interference of high frequency common mode signals on the power supply; A low impedance common mode filter unit is connected to the phase line and the protection conductor and is used to conduct high frequency common mode signals to the protection conductor; A switching unit is connected to the protection conductor and is used to disconnect the loop between the low-impedance common-mode filtering unit and the protection conductor, or to connect the loop between the low-impedance common-mode filtering unit and the protection conductor.

2. The filter according to claim 1, characterized in that The filter comprises: a protection conductor power supply end and a protection conductor load end; the switching unit comprises: a first switch circuit located between the protection conductor power supply end and the protection conductor load end.

3. The filter according to claim 2, characterized in that The first switch circuit includes: a first switch.

4. The filter according to claim 2, characterized in that The switching unit also includes: The magnetic flux suppression circuit is connected to the first switch circuit and is used to suppress the increase of the magnetic flux of the high impedance common mode filter unit after the loop between the low impedance common mode filter unit and the protection conductor is disconnected.

5. The filter according to claim 4, characterized in that The magnetic flux suppression circuit includes: a second switch and a short-circuit coil, and two ends of the short-circuit coil are connected to the second switch.

6. The filter according to claim 5, characterized in that When the first switch circuit connects the loop between the low-impedance common-mode filter unit and the protection conductor, the second switch disconnects the short-circuit coil; when the first switch circuit disconnects the loop between the low-impedance common-mode filter unit and the protection conductor, the second switch short-circuits the short-circuit coil.

7. The filter according to claim 5, characterized in that The high impedance common mode filter unit comprises: a magnetic ring, and a first winding, a second winding and a third winding wound on the magnetic ring, wherein the first winding to the third winding are respectively connected to different phase lines.

8. The filter according to claim 7, characterized in that The short-circuit coil is wound around the magnetic ring.

9. The filter according to claim 8, characterized in that The short-circuit coil is located between any two phase windings.

10. The filter according to claim 1, characterized in that The differential mode signal suppression unit is a differential mode capacitor group.

11. The filter according to claim 1, characterized in that The low impedance common mode filtering unit is a common mode capacitor group.

12. A power supply system, characterized in that: include: power supply; A filter as claimed in any one of claims 1 to 11; and load; One end of the filter is connected to the phase line output end of the power supply, and the other end is connected to the load.

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