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KR-102964086-B1 - Improved low-EMI transformer

KR102964086B1KR 102964086 B1KR102964086 B1KR 102964086B1KR-102964086-B1

Abstract

The present invention relates to a transformer (100e1) comprising: i) a magnetizable core (110) having individual primary and secondary coils; ii) a grounding terminal (PE) for electrically connecting to an external grounding terminal (999) of a power grid (900); and iii) a physical electrical grounding node (175) positioned within an isolation transformer (100e1), wherein the physical electrical grounding node (175) is electrically connected to the grounding terminal (PE, 199). The transformer (100e1) further comprises: iv) at least two electrically conductive loops (CL1..CL6) positioned at different locations of the transformer (100e1) where a magnetic field may be established during operation; and v) a switching circuit (801) configured to sequentially, temporarily, and optionally electrically couple a subset (SS) of the electrically conductive loops (CL1..CL6) with the physical electrical grounding node (175) according to a specific sequence and pattern. The present invention provides an isolation transformer that is much less susceptible to EMI effects without the need to apply standards. Additionally, the transformer does not require field adjustment or calibration.

Inventors

  • 프리스볼드, 에를렌
  • 스바네스, 에릭 셸란드

Assignees

  • 이존 에너지 에이에스

Dates

Publication Date
20260513
Application Date
20220822
Priority Date
20210923

Claims (15)

  1. ― Magnetizable core (110); ― At least one primary coil (120, 120-1..120-3) and at least one secondary coil (130, 130-1..130-3) provided around the magnetizable core (110); ― A grounding terminal (PE) for electrically connecting to an external grounding terminal (999) of the power grid; and — A transformer (100e1) comprising a physical electrical ground node (175) positioned within the transformer (100e1) and electrically connected to the ground terminal (PE, 199), The above transformer (100e1) is, ― At least two electrically conductive loops (CL1..CL6) placed at different locations of the transformer (100e1) where a magnetic field can be established during operation; and — A transformer (100e1) further comprising a switching circuit (801) configured to sequentially, temporarily, and optionally electrically couple a subset (SS) of the electrically conductive loops (CL1..CL6) with the physical electrical ground node (175) according to a specific sequence and pattern.
  2. In paragraph 1, A transformer (100e1) comprising at least two electrically conductive loops (CL1..CL6) and at least three electrically conductive loops.
  3. In paragraph 2, A transformer (100e1) comprising at least 6 electrically conductive loops, wherein at least 2 of the above electrically conductive loops (CL1..CL6).
  4. In any one of paragraphs 1 through 3, A transformer (100e1) in which at least two of the above-mentioned electrically conductive loops (CL1..CL6) are disposed in the space between the coils (120, 120-1..120-3, 130, 130-1..130-3).
  5. In any one of paragraphs 1 through 3, At least two of the above electrically conductive loops (CL1..CL6) are integrated into a plate (800-1, 800-2) or multiple plates (800-1, 800-2), which are laminated with a material that is permeable to magnetic fields and electrically insulating, in a transformer (100e1).
  6. In any one of paragraphs 1 through 3, A subset (SS) of the above electrically conductive loops (CL1..CL6) forms a pair of electrically conductive loops (CL1..CL6), a transformer (100e1).
  7. In any one of paragraphs 1 through 3, The above specific sequence and pattern is a transformer (100e1) that substantially covers all electrically conductive loops (CL1..CL6).
  8. In any one of paragraphs 1 through 3, The above specific sequence and pattern constitute a predetermined order of selection of a subset (SS) of electrically conductive loops (CL1..CL6), transformer (100e1).
  9. In any one of paragraphs 1 through 3, The above specific sequence and pattern constitute a random order of selection of a subset (SS) of electrically conductive loops (CL1..CL6), transformer (100e1).
  10. In any one of paragraphs 1 through 3, The above magnetizable core (110) is floating and electrically insulated from all parts accessible from the outside of the transformer (100e1), the transformer (100e1).
  11. In any one of paragraphs 1 through 3, The transformer (100e1) comprises three sets of coils (120-1..120-3, 130-1..130-3), each set comprising at least one primary coil (120-1..120-3) and at least one secondary coil (130-1..130-3) to form a three-phase transformer (100e1).
  12. In Paragraph 11, The above magnetizable core (110) comprises at least three legs (110I1..110I3), with at least one for each pair of primary coil and secondary coil, in a transformer (100e1).
  13. In any one of paragraphs 1 through 3, The transformer (100e1) further comprises a Faraday cage (150) in which the magnetizable core (110), the individual coils (120-1..120-3, 130-1..130-2), and at least two conductive loops (CL1..CL6) are disposed, wherein the Faraday cage (150) is electrically connected to a physical electrical ground node (175).
  14. ― Terminals (L1, L2, L3) for connection with the power grid (900); ― Dedicated ground (999) for forming an external ground terminal; ― A power supply network including all necessary cables, electrical contacts, and plugs; and A power system (1000) comprising a transformer (100e1) according to any one of claims 1 to 3, wherein the input terminal of the transformer (100e1) is electrically connected to a power supply network and the ground terminal (PE) of the transformer (100e1) is electrically connected to the dedicated ground (999).
  15. As a method for improving the performance of an electric or electronic device (1), ― Step of placing at least two electrically conductive loops (CL1..CL3) at different locations of the device (1) where a magnetic field can be established during the operation of the device (1), and ― Step of sequentially, temporarily, and optionally electrically coupling a subset of the above electrically conductive loops (CL1..CL3) to a physical electrical ground node (175) according to a specific sequence and pattern A method for improving the performance of an electrical or electronic device (1), including.

Description

Improved low-EMI transformer The present invention relates to a transformer comprising a magnetizable core, at least one primary coil provided around the magnetizable core, and at least one secondary coil, a grounding terminal for electrically connecting to an external grounding terminal of a power grid, and a physical electrical grounding node positioned within the transformer, wherein the physical electrical grounding node is electrically connected to the grounding terminal. The present invention also relates to a power system comprising such a transformer. The present invention also relates to a method for improving the performance of an electrical or electronic device. Isolation transformers block the transmission of the DC component of a signal from one circuit to another, while allowing the AC component to pass through. Transformers with a 1:1 ratio between the primary and secondary windings are often used to protect secondary circuits and individuals from electric shock between the energized conductor and ground. Properly designed isolation transformers block interference caused by ground loops. Isolation transformers with electrostatic shielding capabilities are used in power supplies for sensitive equipment such as computers, medical devices, or laboratory equipment. Faraday cages are generally used to block electric fields. External electric fields disperse charges within the conductive material (constituting the cage), thereby canceling out the effects of the electric field inside the cage. This phenomenon is used to protect sensitive electronic equipment inside the cage from external radio frequency interference (RFI). Faraday cages are also used to surround devices that generate RFI themselves, such as radio transmitters. Subsequently, Faraday cages prevent radio waves from interfering with other nearby equipment located outside the individual cages. When the electromagnetic field changes, the faster the change (i.e., the higher the frequency), the greater the material's resistance to magnetic field penetration. In such cases, shielding depends on electrical conductivity, the magnetic properties of the electrically conductive material used in the cage, and its thickness. The problem with the aforementioned known isolation transformer is that, even when used in accordance with international standards for isolation transformer connections, it still suffers from significant electric magnetic interference (EMI). Noise levels can be much higher than the specified maximum allowable levels. Therefore, further improvements to the isolation transformer are clearly necessary. The most relevant international standard is "2011 NEC," which refers to UL, CSA, and NEMA standards (NEMA ST-20). The inventors previously proposed in WO 2019/013642 a low-EMI transformer comprising: i) a Faraday cage comprising a magnetic core, at least one primary coil, and at least one secondary coil; ii) an input terminal connected to at least one primary coil via an input wire; iii) an output terminal connected to at least one secondary coil via an output wire; and iv) an input ground terminal for connecting to the Faraday cage and an output ground terminal connected to the Faraday cage for additional connection to an additional circuit to be connected to the isolation transformer. The isolation transformer of WO 2019/013642 further comprises: v) a clean ground input terminal for receiving an external clean ground; vi) a clean ground output terminal for connecting to an additional clean ground input terminal of an additional circuit; and vii) a physical electric node positioned within the Faraday cage where the magnetic flux and electric field are lowest, preferably close to zero. The clean ground input terminal is electrically supplied to the isolation transformer and connected to the physical electric node via a first electrical connection. In addition, the physical electrical node is further electrically connected to the clean ground output terminal through a second electrical connection. An important feature of the transformer in WO 2019/013642 is that it is provided with a separate (additional) input terminal to receive clean ground and a separate (additional) output terminal to supply clean ground to an additional circuit, whereas in previous prior art solutions, all grounds are interconnected, meaning there is no separate low-EMI ground. The (normal) input ground terminal is connected to a Faraday cage, which may also be additionally connected to another Faraday cage of a different circuit, which is also the case with previous prior art solutions. The clean ground input terminal is supplied to a physical electric node, from which it is further supplied toward the clean ground output terminal. The inventors have found that the placement of this physical electric node is very important, namely that it must be placed where the magnetic flux is lowest and the electric field is lowest. Furthermore, the ideal location of the p