Filter circuit and filter for rectification inverter

Abstract

The embodiment of the utility model provides a filter circuit and a filter for a rectification inverter. The filter circuit comprises a common-mode filter module which comprises a common-mode filter inductor which is connected in series with a plurality of power lines; the multiple pairs of first filter capacitors are coupled to the multiple power lines respectively, each pair of first filter capacitors is arranged at the two ends of the male mode filter inductor respectively, the first ends of the first filter capacitors are coupled to the corresponding power lines, and the second ends of the first filter capacitors are coupled to the ground; the magnetic ring is arranged on the side, facing the power supply side, of the common-mode filtering module and at least partially surrounds the outer sides of the power lines; and the plurality of second filter capacitors are arranged on the side, away from the common-mode filter module, of the magnetic ring, the first ends of the plurality of second filter capacitors are respectively coupled to the plurality of power lines, and the second ends of the plurality of second filter capacitors are grounded. Therefore, various interference signals generated by a noise source can be suppressed.

Description

Technical Field

[0001] The exemplary embodiments disclosed herein generally relate to the field of electrical equipment, and particularly to filter circuits and filters for rectifier inverters. Background Technology

[0002] With the development of new semiconductor technologies, the operating frequency of Insulated-Gate Bipolar Transistors (IGBTs) is increasing. As a core component of three-phase four-wire active power filters (APFs) and static var generators (SVGs), increasing the operating frequency of IGBTs can effectively improve the power density of products, but it also causes more severe high-frequency electromagnetic interference.

[0003] These high-frequency electromagnetic interferences can affect other devices in the same microgrid environment through cables and spatial radiation, and may even cause other devices to malfunction or shut down. Utility Model Content

[0004] In a first aspect of this disclosure, a filter circuit for a rectifier inverter is provided. The filter circuit is arranged between a power supply side and a noise source, and includes: a common-mode filter module adapted to filter interference signals on multiple power lines between the power supply side and the noise source, and includes: a common-mode filter inductor connected in series on the multiple power lines; and multiple pairs of first filter capacitors, respectively coupled to the multiple power lines, each pair of first filter capacitors being arranged at both ends of the common-mode filter inductor, with a first end of the first filter capacitor coupled to the corresponding power line and a second end of the first filter capacitor coupled to ground; a magnetic ring arranged on the side of the common-mode filter module facing the power supply side and at least partially surrounding the outside of the multiple power lines; and multiple second filter capacitors arranged on the side of the magnetic ring away from the common-mode filter module, with the first ends of the multiple second filter capacitors respectively coupled to the multiple power lines and the second ends of the multiple second filter capacitors grounded.

[0005] In some embodiments, the filtering circuit further includes: at least one third filtering capacitor disposed between the magnetic ring and the common-mode filtering module, wherein the first end of the at least one third filtering capacitor is coupled to at least one live wire of the plurality of power lines, and the second end of the at least one third filtering capacitor is coupled to the neutral wire of the plurality of power lines.

[0006] In some embodiments, the filtering circuit further includes: at least one fourth filter capacitor disposed on the side of the common-mode filtering module near the noise source, and the first end of the at least one fourth filter capacitor is coupled to at least one live wire of the plurality of power lines, and the second end of the at least one fourth filter capacitor is coupled to the neutral wire of the plurality of power lines.

[0007] In some embodiments, the filter inductor is a nickel-zinc ferrite inductor.

[0008] In some embodiments, the magnetic ring is a nanocrystalline magnetic ring.

[0009] In some embodiments, the cross-section of the magnetic ring perpendicular to the axis is elliptical.

[0010] According to the filtering circuit provided in this disclosure, it suppresses high-frequency and low-frequency noise generated by the noise source from being conducted to the power supply side by using a common-mode filter module, a magnetic ring, and multiple filter capacitors arranged between the power supply side and the noise source. The common-mode inductor module is suitable for suppressing relatively low-frequency common-mode interference and some differential-mode interference generated by the noise source, while the magnetic ring and multiple second filter capacitors arranged near the power supply side of the magnetic ring are suitable for suppressing high-frequency interference generated by the noise source. In this way, high-frequency and low-frequency interference generated by the noise source can be effectively reduced. Furthermore, the combination of the magnetic ring, common-mode inductor module, and multiple filter capacitors reduces the overall space occupied by the filtering circuit and lowers manufacturing costs.

[0011] In a second aspect of this disclosure, a filter is provided. The filter includes: a housing; and a filtering circuit according to a first aspect of this disclosure.

[0012] In some embodiments, the housing includes an opening formed on one side, and the filter further includes: a top cover coupled to the housing to shield the opening; and a shielding cover disposed within the housing to surround a shielding cavity with the housing and the top cover, wherein the filter circuitry is at least partially disposed within the shielding cavity.

[0013] In some embodiments, a plurality of second filter capacitors of the filter circuit are arranged inside a shielded cavity.

[0014] In some embodiments, the filter further includes two sets of springs, respectively arranged on the sides of the shield facing the housing and facing the top cover, so that the shield is sealed to the housing and the top cover.

[0015] It should be understood that the content described in this content section is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0016] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0017] Figure 1 A simplified circuit diagram of a filter circuit according to some embodiments of the present disclosure is shown; and

[0018] Figure 2 A schematic diagram of the internal structure of a filter according to an embodiment of the present disclosure is shown. Detailed Implementation

[0019] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0020] It should be noted that the headings of any section / subsection provided herein are not limiting. Various embodiments are described throughout this document, and embodiments of any type may be included under any section / subsection. Furthermore, embodiments described in any section / subsection may be combined in any way with any other embodiments described in the same section / subsection and / or different sections / subsections.

[0021] In the description of embodiments of this disclosure, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The term "some embodiments" should be understood as "at least some embodiments". Other explicit and implicit definitions may also be included below. The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0022] As briefly mentioned earlier, for high-frequency insulated-gate bipolar transistors (IGBTs), traditional techniques often employ multiple common-mode inductors to suppress noise. However, this suppression method is only effective for low-frequency noise. It often fails to meet the requirements for suppressing high-frequency noise. Furthermore, the multiple common-mode inductor suppression method also suffers from drawbacks such as large size and high cost.

[0023] The filter circuit and filter for a rectifier inverter provided in this disclosure solve, or at least partially solve, the aforementioned problems and other potential problems existing in conventional solutions. The filter circuit for a rectifier inverter provided in this disclosure suppresses high-frequency and low-frequency noise generated by the differential mode of the noise source from being conducted to the power supply side by means of a common-mode filter module, a magnetic ring, and multiple filter capacitors arranged between the power supply side and the noise source. The common-mode inductor module is suitable for suppressing relatively low-frequency common-mode interference and a portion of differential-mode interference generated by the noise source, while the magnetic ring and multiple second filter capacitors arranged near the power supply side of the magnetic ring are suitable for suppressing high-frequency interference generated by the noise source. In this way, high-frequency and low-frequency interference generated by the noise source (e.g., an insulated-gate bipolar transistor) can be effectively reduced. Furthermore, the combination of the magnetic ring, the common-mode inductor module, and multiple filter capacitors reduces the overall space occupied by the filter circuit and lowers manufacturing costs.

[0024] Figure 1 A simplified circuit diagram of a filter circuit according to some embodiments of the present disclosure is shown. Figure 1 As shown, the filter circuit is arranged between the power supply side 9 and the noise source 8, and is adapted to suppress the transmission of interference signals generated by the noise source 8 to the power supply side 9. The filter circuit generally includes a common-mode filter module 1, a magnetic ring 2 arranged on the side of the common-mode filter module 1 facing the power supply side 9, and a plurality of second filter capacitors 3 arranged on the side of the magnetic ring 2 away from the filter module.

[0025] In some embodiments, the power supply side 9 and the noise source 8 are connected by a three-phase four-wire power supply structure, meaning the power lines between the power supply side 9 and the noise source 8 include three live wires (L1, L2, and L3) and one neutral wire. In some embodiments, the power supply side 9 and the noise source 8 can also be connected by any other suitable power supply structure, for example, one live wire and one neutral wire may be connected between the power supply side 9 and the noise source 8.

[0026] The common-mode filtering module 1 includes a common-mode filtering inductor 11 and multiple pairs of first-mode filtering capacitors 12. The common-mode filtering inductor 11 is arranged on multiple power lines between the noise source 8 and the power supply side 9. For example, the three-phase live wires and one-phase neutral wire of the power supply side 9 are coupled to one end of the common-mode filtering inductor 11, and the three-phase live wires and one-phase neutral wire of the noise source 8 are coupled to the other end of the common-mode filtering inductor 11. The multiple pairs of first-mode filtering capacitors 12 correspond to multiple power lines, and each pair of first-mode filtering capacitors 12 is arranged on both sides of the common-mode filtering inductor 11 along a power line. One end of each first-mode filtering capacitor 12 is coupled to the corresponding power line, and the other end is grounded. In this way, the filtering inductor 11 and the multiple pairs of first-mode filtering capacitors 12 on both sides can form a π-shaped filter, which can suppress low-frequency common-mode interference and some differential-mode interference in the power lines.

[0027] In some embodiments, the common-mode filter inductor 11 can be a nickel-zinc ferrite inductor, which can provide a high common-mode impedance. During the passage of the common-mode interference signal through the common-mode filter inductor 11, the common-mode impedance provided by the common-mode filter inductor 11 can reflect most of the common-mode interference signal, thereby suppressing the conducted emission of the interference signal. The first filter capacitors 12 arranged in pairs on both sides of the common-mode filter inductor 11 are adapted to provide a low-impedance loop to the common-mode interference signal, bypassing the interference signal to the chassis.

[0028] The magnetic ring 2 at least partially surrounds the outside of multiple power lines and is adapted to filter high-frequency interference signals within the multiple power lines. In some embodiments, the magnetic ring 2 may be a nanocrystalline magnetic ring, which has a wider filtering bandwidth than conventional material magnetic rings, thus providing better suppression of high-frequency (e.g., 150kHz) interference signals. In some embodiments, the cross-section of the magnetic ring 2 perpendicular to the axis may be elliptical. An elliptical magnetic ring 2 is easier to manufacture and also reduces space requirements. In other embodiments, the cross-section of the magnetic ring 2 perpendicular to the axis may also be circular or oblong.

[0029] In some embodiments, at least one third filter capacitor 4 is further disposed on the side of the magnetic ring 2 facing the common-mode filter module 1. The at least one third filter capacitor 4 corresponds to at least one live wire among the plurality of power lines, and one end of the third filter capacitor 4 is coupled to the corresponding live wire, while the other end is coupled to the neutral wire. In some embodiments, the plurality of power lines include three live wires and one neutral wire; therefore, three third filter capacitors 4 are arranged between the magnetic ring 2 and the common-mode filter module 1. The three third filter capacitors 4, together with the magnetic ring 2, can form an inductor-capacitor sub-circuit, thereby further eliminating interference signals in the power lines.

[0030] Multiple second filter capacitors 3 are respectively associated with multiple power lines, with one end of each capacitor coupled to a power line and the other end grounded. In some conventional active power filter designs, the power supply side 9 is often close to printed circuit boards (PCBs) containing high-speed signals, such as the control board, auxiliary power supply, and drive board of the active power filter. These high-speed signals often generate severe high-frequency interference. Placing multiple second filter capacitors 3 near the power supply side 9 on the power lines can further eliminate this high-frequency interference. In some embodiments, the second filter capacitors 3 can also be selected as capacitors with smaller capacitance values; for example, the capacitance value of the second filter capacitor 3 can be smaller than that of the first filter capacitor 12. The smaller capacitance value of the second filter capacitor 3 can more effectively filter out this high-frequency interference.

[0031] In some embodiments, the filtering circuit further includes at least one fourth filter capacitor 5, which is arranged on the side of the common-mode filtering module 1 near the noise source 8. Each fourth filter capacitor 5 corresponds to at least one live wire, with one end of each fourth filter capacitor 5 coupled to the live wire and the other end coupled to the neutral wire. Common-mode interference in the power line is, to some extent, converted from differential-mode interference generated by the noise source 8. Therefore, by arranging at least one fourth filter capacitor 5 between the common-mode filtering module 1 and the noise source 8, differential-mode interference can be reduced, thereby indirectly reducing common-mode interference, thus reducing the noise reduction burden on the common-mode filtering module 1.

[0032] Figure 2 A schematic diagram of the internal structure of a filter according to an embodiment of the present disclosure is shown. Figure 2 As shown, the filter generally includes a housing 6 and filter circuitry arranged within the housing 6. In some embodiments, the filter circuitry is arranged within the housing 6 in the form of a circuit board.

[0033] In some embodiments, the filter housing 6 has an open side, and the opening is covered by a cover suitable for concealing the opening. A shielding cover 7 is also arranged inside the housing 6, the shielding cover 7 being bent in a suitable manner within the housing 6, so that the shielding cover 7, together with the housing 6 and the cover, encloses a shielding cavity. At least a portion of the filter circuit can be arranged within the shielding cavity to reduce electromagnetic interference from the power line to the outside. In some embodiments, a plurality of second filters of the filter circuit can be arranged within the shielding cavity. In this way, the shielding cavity can shield interference signals from the power line at the second filters. In some other embodiments, all or any other suitable portion of the filter circuit can also be arranged within the shielding cavity.

[0034] In some embodiments, the shielding cover 7 is coupled with two sets of springs 71 on the side facing the top cover and the side away from the top cover (that is, the side facing the housing 6). The two sets of springs 71 are pressed against the housing 6 and the top cover respectively to improve the sealing of the shielding cover 7 with the top cover and the housing 6, thereby improving the shielding performance of the shielding cavity.

[0035] Various implementations of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed implementations. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described implementations. The terminology used herein is chosen to best explain the principles, practical applications, or improvements to technology in the market, or to enable others skilled in the art to understand the various implementations disclosed herein.

Claims

1. A filter circuit for a rectifier-inverter, arranged between a supply side (9) and a source of noise (8), characterized in that, Comprises: a common mode filter module (1) adapted to filter interference signals on a plurality of power lines between the power supply side (9) and the noise source (8), and comprising: a common mode filter inductor (11) connected in series on the plurality of power lines; and a plurality of pairs of first filter capacitors (12) respectively coupled to the plurality of power lines, each pair of first filter capacitors (12) of the plurality of pairs of first filter capacitors (12) being arranged across the common mode filter inductor (11) and a first end of the first filter capacitor (12) being coupled to a corresponding power line and a second end of the first filter capacitor (12) being coupled to ground; a magnetic ring (2) arranged on a side of the common mode filter module (1) facing the power supply side (9) and at least partially surrounding outside the plurality of power lines; and a plurality of second filter capacitors (3) arranged on a side of the magnetic ring (2) facing away from the common mode filter module (1) and a first end of the plurality of second filter capacitors (3) being respectively coupled to the plurality of power lines and a second end of the plurality of second filter capacitors (3) being coupled to ground.

2. The filter circuit of claim 1, wherein, Further comprises: at least one third filter capacitor (4) arranged between the magnetic ring (2) and the common mode filter module (1), a first end of the at least one third filter capacitor (4) being respectively coupled to at least one hot wire of the plurality of power lines and a second end of the at least one third filter capacitor (4) being coupled to a neutral wire of the plurality of power lines.

3. The filter circuit of claim 1, wherein, Further comprises: at least one fourth filter capacitor (5) arranged on a side of the common mode filter module (1) close to the noise source (8) and a first end of the at least one fourth filter capacitor (5) being respectively coupled to at least one hot wire of the plurality of power lines and a second end of the at least one fourth filter capacitor (5) being coupled to a neutral wire of the plurality of power lines.

4. The filter circuit according to any one of claims 1 to 3, characterized in that The common mode filter inductor (11) is a nickel-zinc ferrite inductor.

5. The filter circuit according to any one of claims 1 to 3, characterized in that, The magnetic ring (2) is a nanocrystalline magnetic ring.

6. The filter circuit of any one of claims 1-3, wherein, A cross section of the magnetic ring (2) perpendicular to an axis is elliptical.

7. A filter, characterized by Comprises: a box (6); and a filter circuit according to any one of claims 1-6. The box (6) comprises an opening formed on a side, and 8. The filter of claim 7, wherein, wherein the filter further comprises: an upper cover coupled to the box (6) to shield the opening; and a shield cover (7) arranged inside the box (6) to enclose a shield cavity with the box (6) and the upper cover, wherein the filter circuit is at least partially arranged inside the shield cavity. The plurality of second filter capacitors (3) of the filter circuit are arranged inside the shield cavity.

9. The filter of claim 8, wherein, Further comprises:

10. The filter according to claim 8 or 9, characterized in that two groups of elastic sheets (71) respectively arranged on two sides of the shield cover (7) facing the box (6) and the upper cover so that the shield cover (7) is sealed to the box (6) and the upper cover. ​

Images