CN111108812A - Induction hob comprising an electromagnetic interference filter - Google Patents
Induction hob comprising an electromagnetic interference filter Download PDFInfo
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- CN111108812A CN111108812A CN201880061700.8A CN201880061700A CN111108812A CN 111108812 A CN111108812 A CN 111108812A CN 201880061700 A CN201880061700 A CN 201880061700A CN 111108812 A CN111108812 A CN 111108812A
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Abstract
An induction hob is disclosed, comprising an AC power input (2) and a power conversion mechanism (3), which is adapted to provide a high frequency current to an induction coil, wherein an electromagnetic filtering portion (1) is arranged between the AC power input (2) and the power conversion mechanism (3), the electromagnetic filtering portion (1) comprising a common mode filter device and a differential mode filter device, wherein the electromagnetic filter part (1) comprises a closed magnetic core element (4) around which at least two coils (5, 6) are arranged, said closed magnetic core element (4) and said coils (5, 6) providing said common mode filtering means, and wherein the differential mode filtering means are configured to achieve a forward magnetic flux between the coil ends (5.1, 5.2, 6.1, 6.2) of each coil (5, 6) for obtaining a differential mode filtering effect.
Description
The present invention generally relates to the field of induction cookers. More particularly, the present invention relates to an induction hob comprising an electromagnetic interference filter for filtering interference occurring in a power unit of the induction hob.
Background
Induction hobs for preparing food are well known in the prior art. Typically, the induction hob comprises at least one heating zone, which is associated with at least one induction coil. In order to heat a cooker placed on the heating area, the induction coil is coupled with an electronic driving device (hereinafter, referred to as a power unit) for driving an Alternating Current (AC) current through the induction element. The power unit may include an AC power input and a power conversion mechanism to provide high frequency current to the induction coil.
Disadvantageously, high-frequency noise is generated in the power unit. Said high frequency noise has a detrimental effect on the AC mains voltage, for example. Therefore, an electromagnetic interference filter is used to reduce the influence of high frequency noise. The electromagnetic interference filter may comprise a plurality of electrical components in order to achieve a common mode filtering capability and a differential mode filtering capability.
Disclosure of Invention
It is an object of embodiments of the present invention to provide an induction hob including an electromagnetic interference filter with reduced filter complexity. This object is solved by the features of the independent claims. Preferred embodiments are given in the dependent claims. The embodiments of the invention and the individual features of said embodiments can be freely combined with each other, if not explicitly stated otherwise.
According to an aspect, the present invention relates to an induction hob comprising an AC power input (i.e. a mains voltage input) and a power conversion mechanism adapted to provide a high frequency current to an induction coil. An electromagnetic filtering portion is disposed between the AC power input and the power conversion mechanism. Preferably, the electromagnetic filtering portion includes a common mode filter device and a differential mode filter device. The electromagnetic filter part may particularly comprise a closed magnetic core element around which at least two coils are arranged. The closed magnetic core element and the coil preferably provide the common mode filtering means. The differential mode filtering device is more preferably adapted to achieve a forward magnetic flux between the coil ends of each coil in order to obtain a differential mode filtering effect.
The induction hob is advantageous because the electromagnetic filtering portion provides common mode filtering capability and differential mode filtering capability in a single component. Thereby, the installation space and the manufacturing cost of the filter part can be reduced.
According to an embodiment, the closed magnetic core element comprises a ring-like or polygonal shape. The closed magnetic core element may be constructed from a single core element or may comprise a plurality of core element portions that are assembled to construct a closed magnetic core element.
According to an embodiment, the differential mode filter device comprises a rod-shaped or plate-shaped core element arranged between the coils. Based on the rod-shaped or plate-shaped core element, a shortcut of the magnetic flux is created, which is arranged between the electromagnetic coils. The rod-shaped or plate-shaped core element adds a differential mode filtering capability to a common mode filter formed by a closed magnetic core element and a pair of coils.
According to an embodiment, an air gap is provided at one or each side between the rod-shaped or plate-shaped core element and the closed magnetic core element. Thereby, the filtering behavior of the filtering part can be designed according to the required requirements. In particular, the relation between common mode filtering capability and differential mode filtering capability may be adjusted by including one or two air gaps, respectively by selecting the width of the air gaps.
According to an embodiment, said closed magnetic core element comprises core protrusions facing each other at opposite parts of the closed magnetic core element, said core protrusions forming said means for closing magnetic flux between said coils. Thus, in other words, the core projections partially reduce the gap between the core element portions, which extend between the coil ends of the two coils. The core protrusion may be integrally formed at the closed magnetic core element. Preferably, a single air gap is provided in the central region between the two coils and between the core projections.
According to an embodiment, the portion of the closed magnetic core element arranged between the coils comprises an E-shape or substantially E-shape. For example, the upper and lower legs of the E-shaped magnetic core element portion extend into the inner portion of the coil, and the central leg forms a core projection extending into the central portion arranged between the coils.
According to an embodiment, the closed magnetic core element and/or the rod-shaped or plate-shaped core element is an injection molded element or a powder press molded element.
According to an embodiment, the closed magnetic core element and/or the rod-shaped or plate-shaped core element is made of ferrite or laminated metal plate.
According to an embodiment, the coils comprise the same number of windings. Preferably, the coils comprise the same winding direction. Thereby, a symmetric filtering effect is obtained.
According to other embodiments, the coil comprises a different number of turns. Thereby, the differential filtering effect is enhanced.
According to an embodiment, the permeability of the closed magnetic core element and/or the rod-shaped or plate-shaped core element is selected so as to achieve a desired filtering effect. Thereby, a desired filtering capability for induction hob applications may be obtained.
According to another aspect, a method for increasing differential filtering effects in an induction hob is provided. The induction hob includes an AC power input and a power conversion mechanism adapted to provide a high frequency current to the induction coil. The induction hob further comprises an electromagnetic filtering portion arranged between the AC power input and the power conversion mechanism. The electromagnetic filtering part comprises a common mode filtering device and a differential mode filtering device. The electromagnetic filtering portion includes a closed magnetic core element around which at least two coils are arranged. The closed magnetic core element and the coil provide the common mode filtering. The differential mode filter device achieves a forward magnetic flux between coil ends of each coil so as to obtain a differential mode filtering effect.
The terms "substantially", "substantially" or "approximately" as used herein refer to a deviation from the exact value by +/-10%, preferably +/-5%, and/or a variation that is not functionally significant.
Drawings
The various aspects of the invention, including its specific features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:
fig. 1 shows a circuit schematic of a power unit of an induction hob;
FIG. 2 illustrates an electromagnetic filtering portion including common mode filtering capability and differential mode filtering capability based on an additional core portion disposed between coils;
fig. 3 illustrates the cancellation of magnetic flux in a choke comprising a pair of coils and a toroidal core element;
figure 4 illustrates the differential mode filtering capability of a choke additionally comprising a rod-shaped core element;
fig. 5 shows an embodiment of a choke with a rod-shaped core element which is at a distance from a ring-shaped core element by means of an air gap; and is
Fig. 6 shows another embodiment of an electromagnetic filtering portion including core projections between coils, the core projections being separated by a central air gap.
Detailed Description
The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments are shown. However, the present invention should not be construed as being limited to the embodiments set forth herein. Throughout the following description, similar reference numerals are used to denote similar elements, parts, articles or features, where applicable.
Fig. 1 shows an equivalent circuit schematic of a power cell circuitry included in an induction hob.
The circuitry comprises an AC power input 2, a power conversion mechanism 3 and an electromagnetic filtering portion 1 comprised between said AC power input 2 and said power conversion mechanism 3. The AC power input 2 provides AC mains power to the power conversion mechanism 3 to enable supply of electrical power to an induction coil coupled to the power conversion mechanism 3. The power conversion mechanism 3 may provide an electronic drive means for driving an AC current through the induction coil. For example, the power conversion mechanism 3 may include a switching section including one or more switching elements (such as IGBTs) and a resonance section that oscillates by means of the switching section.
In order to avoid or suppress interference between the AC power input 2 and the power conversion mechanism 3, the electromagnetic filtering portion 1 provides an electrical filtering capability. Specifically, the electromagnetic filtering portion 1 is adapted to suppress high-frequency interference that is generated in the power conversion mechanism 3 and has an adverse effect on the AC power input terminal 2.
In order to face the common mode interference and the differential mode interference, the electromagnetic filtering portion 1 includes a common mode filter device and a differential mode filter device.
In the prior art electromagnetic filtering section comprised in an induction hob, the common mode and differential mode filtering devices are provided by different filtering sections, namely a common mode filtering section 1.1 and a differential mode filtering section 1.2 highlighted by a dashed box in the equivalent circuit schematic of fig. 1. Furthermore, the common-mode filter section 1.1 and the differential-mode filter section 1.2 may comprise different electronic components for realizing the filter sections 1.1, 1.2.
Fig. 2 shows an embodiment of an electromagnetic filtering portion 1 combining common mode filtering capabilities and differential mode filtering capabilities in a single electronic device. The electromagnetic filtering portion 1 includes a choke coil including a common mode filter device and a differential mode filter device.
In more detail, the choke comprises a closed magnetic core element 4 and a pair of coils 5, 6 arranged at said closed magnetic core element 4. In more detail, the closed magnetic core element 4 comprises a first coil part 4.1 and a second coil part 4.2, the coils 5, 6 being arranged at the first coil part and the second coil part. In particular, the winding of the coil 5 is wound on the first coil portion 4.1 and the winding of the coil 6 is wound on the second coil portion 4.2. The first coil portion 4.1 and the second coil portion 4.2 may be arranged opposite each other.
Furthermore, the closed magnetic core element 4 comprises a pair of coupling parts 4.3, 4.4, which coupling parts 4.3, 4.4 couple the first and second coil parts 4.1, 4.2 on opposite sides. In more detail, the coupling portion 4.3 may be arranged between the free ends 5.1, 6.1 of the coils 5, 6, and the coupling portion 4.4 may be arranged between the free ends 5.2, 6.2 of the coils 5, 6. Thereby providing a closed magnetic core element 4.
The closed magnetic core element 4 may comprise a ring, a circle or a polygon, in particular a rectangle or a square, shape.
The closed core element 4 comprising the pair of coils 5, 6 for achieving the electrical coupling between the AC power input 2 and the power conversion mechanism 3 acts as a common mode filtering choke, since electrical noise signals flowing in the same direction cause a high impedance within the choke and are therefore suppressed.
However, common mode filter chokes do not include differential filtering capability because, as shown in fig. 3, the differential mode current (I) flows1，I2) The induced magnetic fluxes cancel each other out and thus the impedance of the differential mode current is low.
In order to enhance the differential-mode filtering capability, the choke comprises a plate-shaped or rod-shaped core element 7 (see fig. 1). The plate-shaped or rod-shaped core elements 7 may be arranged symmetrically between the coils 5, 6. The core element 7 may provide a magnetic flux between the coupling parts 4.3, 4.4. According to an embodiment, the free end of the core element 7 may abut at the coupling portion 4.3, 4.4.
As shown in FIG. 4, the differential mode current (I)1，I2) The resulting magnetic flux has the same flow direction in the plate-shaped or rod-shaped core element 7, which improves the differential mode filtering capability.
Fig. 5 shows another embodiment of a choke that achieves both common mode filtering capability and differential mode filtering capability. In view of the embodiment of fig. 2, the main difference of the embodiment according to fig. 5 is that an air gap 8 is provided between the closed magnetic core element 4 and the plate-shaped or rod-shaped core element 7. Said air gap 8 may be provided at one free end of the core element 7, i.e. at one of the coupling parts 4.3, 4.4, or at both free ends of the core element 7, i.e. at the free end arranged close to the coupling part 4.3 and at the free end arranged close to the coupling part 4.4.
The filter response of the electromagnetic filter portion 1 can be selected by the material and dimensions of the core element 7, respectively by the air gap 8. The greater the length, width and/or thickness of the core element 7, the greater the effect of the differential mode filtering effect, since the magnetic flux through the core element 7 increases and thus the attenuation increases.
In turn, closing one or more air gaps 8 between the magnetic core element 4 and the plate-or rod-shaped core element 7 reduces the magnetic flux passing through the core element 7 and thus reduces the attenuation, correspondingly reducing the differential mode filtering effect.
Fig. 6 shows another embodiment of the electromagnetic filter portion 1. In contrast to the above described embodiments, the plate-shaped or rod-shaped core element 7 is eliminated on the basis of a pair of core projections 4a, 4 b. The first core projection 4a may be provided at the first coupling portion 4.3 and the second core projection 4b may be provided at the second coupling portion 4.4. The core projections 4a, 4b may be oriented towards the free center of the choke and may face each other. Thus, in other words, the core protrusions 4a, 4b may reduce the distance between the first coupling part 4.3 and the second coupling part 4.4 in the area between the coils 5, 6. Preferably, an air gap 8 is provided between the free ends of the core projections 4a, 4 b.
As mentioned before, the dimensions (length, width and/or height) of the core projections 4a, 4b and the dimensions of the air gap 8 have an influence on the choke, respectively on the differential-mode filtering effect of the electromagnetic filtering portion 1 and can be dimensioned according to the desired filtering effect.
The closed magnetic core element 4 and/or the plate-shaped or rod-shaped core element 7 may be manufactured by injection molding or powder press molding. Alternatively or in addition, the closed magnetic core element 4 and/or the plate-shaped or rod-shaped core element 7 may be made of ferrite or laminated metal sheet.
The coils 5, 6 may comprise the same number of turns and the same winding direction (see fig. 3 and 4). According to other embodiments, the number of turns of the coils 5, 6 may be different in order to enhance the differential filtering effect.
It should be noted that the description and drawings merely illustrate the principles of the proposed invention. Those skilled in the art will be able to implement various arrangements that embody the principles of the invention and are not explicitly described or illustrated herein.
List of reference numerals
1 electromagnetic filter part
1.1 common mode Filter part
1.2 differential mode filtering part
2 AC power input
3 Power conversion mechanism
4 closed magnetic core element
4a, 4b core projection
4.1 coil part
4.2 coil part
4.3 coupling parts
4.4 coupling parts
5 coil
5.1 coil end
5.2 coil ends
6 coil
6.1 coil end
6.2 coil end
7 plate/rod core element
8 air gap
Claims (15)
1. An induction hob comprising an AC power input (2) and a power conversion mechanism (3) adapted to provide a high frequency current to an induction coil, wherein an electromagnetic filtering part (1) is arranged between the AC power input (2) and the power conversion mechanism (3).
2. Induction hob according to claim 1, wherein the electromagnetic filtering portion (1) comprises a common mode filter device and a differential mode filter device, and wherein the electromagnetic filtering portion (1) preferably comprises a closed magnetic core element (4), more preferably at least two coils (5, 6) are arranged around the closed magnetic core element.
3. Induction hob according to any one of the claims 1 or 2, in particular according to claim 2, wherein said common mode filter means are provided in the form of said closed magnetic core element (4) and said coils (5, 6).
4. Induction hob according to any one of the preceding claims, in particular according to claim 2, wherein said differential mode filtering means are adapted to achieve a forward magnetic flux between coil ends (5.1, 5.2, 6.1, 6.2) of each coil (5, 6) in order to obtain a differential mode filtering effect.
5. Induction hob according to any one of the preceding claims, wherein the closed magnetic core element (4) comprises a ring-like or polygonal shape.
6. Induction hob according to any one of the preceding claims, wherein the differential mode filtering means comprise a rod-shaped or plate-shaped core element (7) arranged between the coils (5, 6).
7. Induction hob according to claim 3, wherein an air gap (8) is provided at one or each side between the rod-shaped or plate-shaped core element (7) and the closed magnetic core element (4).
8. Induction hob according to claim 1 or 2, wherein said closed magnetic core element (4) comprises core protrusions (4a, 4b) facing each other at opposite parts of the closed magnetic core element (4), said core protrusions (4a, 4b) forming said means for closing the magnetic flux between said coils (5, 6).
9. Induction hob according to claim 5, wherein the portion of the closed magnetic core element arranged between said coils (5, 6) comprises an E-shape or a substantially E-shape.
10. Induction hob according to any one of the preceding claims, wherein the closed magnetic core element (4) and/or the rod-shaped or plate-shaped core element (7) is an injection molded element or a powder press molded element.
11. Induction hob according to any one of claims 1 to 6, wherein the closed magnetic core element (4) and/or the rod-shaped or plate-shaped core element (7) is made of ferrite or laminated metal sheet.
12. Induction hob according to any one of the preceding claims, wherein the coils (5, 6) comprise the same number of turns or different numbers of turns.
13. Induction hob according to any one of the preceding claims, wherein the coils (5, 6) comprise the same winding direction.
14. Induction hob according to any one of the preceding claims, wherein the magnetic permeability of the closed magnetic core elements (4) and/or the rod-shaped or plate-shaped core elements (7) is selected so as to achieve a desired filtering capacity for induction hob applications.
15. Method for increasing the differential filtering effect in an induction hob comprising an AC power input (2) and a power conversion mechanism (3) adapted to provide a high frequency current to an induction coil, said induction hob further comprising an electromagnetic filtering part (1) arranged between said AC power input (2) and said power conversion mechanism (3), said electromagnetic filtering part (1) comprising a common mode filter device and a differential mode filter device, wherein said electromagnetic filtering part (1) comprises a closed magnetic core element (4) around which at least two coils (5, 6) are arranged, said closed magnetic core element (4) and said coils (5, 6) providing said common mode filtering, and wherein said differential mode filter device causes a coil end (5.1, 5.2, 6.1, 6.2) to obtain a differential mode filtering effect.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP19083935 | 2017-10-25 | ||
| EP171983935 | 2017-10-25 | ||
| PCT/EP2018/077280 WO2019081189A1 (en) | 2017-10-25 | 2018-10-08 | Induction hob comprising an electromagnetic interference filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111108812A true CN111108812A (en) | 2020-05-05 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201880061700.8A Pending CN111108812A (en) | 2017-10-25 | 2018-10-08 | Induction hob comprising an electromagnetic interference filter |
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| Country | Link |
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| CN (1) | CN111108812A (en) |
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| EP2512205A1 (en) * | 2009-12-11 | 2012-10-17 | Panasonic Corporation | Induction heating apparatus and induction heating cooker provided with same |
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| CN103748774A (en) * | 2011-08-25 | 2014-04-23 | 华为技术有限公司 | Common mode inductance apparatus and method |
| CN104064327A (en) * | 2013-03-20 | 2014-09-24 | 施耐德东芝换流器欧洲公司 | Differential Mode And Common Mode Choke |
| CN204168515U (en) * | 2014-11-01 | 2015-02-18 | 朗格森(西安)电子有限公司 | A kind of electromagnetic oven resonant transform circuit |
| CN104539148A (en) * | 2014-11-27 | 2015-04-22 | 华为技术有限公司 | Filter circuit and device |
| CN106098321A (en) * | 2016-07-05 | 2016-11-09 | 海宁联丰东进电子有限公司 | A kind of assembly type multifunctional filter |
| CN206149135U (en) * | 2016-11-02 | 2017-05-03 | 浙江绍兴苏泊尔生活电器有限公司 | EMC filter circuit and electromagnetism stove |
| CN206313657U (en) * | 2016-11-02 | 2017-07-07 | 浙江绍兴苏泊尔生活电器有限公司 | EMC filter circuit and electromagnetism stove |
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2018
- 2018-10-08 CN CN201880061700.8A patent/CN111108812A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2512205A1 (en) * | 2009-12-11 | 2012-10-17 | Panasonic Corporation | Induction heating apparatus and induction heating cooker provided with same |
| CN102856036A (en) * | 2011-06-30 | 2013-01-02 | 艾默生网络能源有限公司 | Difference and common mode integrated inductor, EMI (electromagnetic interference) filter and switch power source |
| CN103748774A (en) * | 2011-08-25 | 2014-04-23 | 华为技术有限公司 | Common mode inductance apparatus and method |
| CN104064327A (en) * | 2013-03-20 | 2014-09-24 | 施耐德东芝换流器欧洲公司 | Differential Mode And Common Mode Choke |
| CN204168515U (en) * | 2014-11-01 | 2015-02-18 | 朗格森(西安)电子有限公司 | A kind of electromagnetic oven resonant transform circuit |
| CN104539148A (en) * | 2014-11-27 | 2015-04-22 | 华为技术有限公司 | Filter circuit and device |
| CN106098321A (en) * | 2016-07-05 | 2016-11-09 | 海宁联丰东进电子有限公司 | A kind of assembly type multifunctional filter |
| CN206149135U (en) * | 2016-11-02 | 2017-05-03 | 浙江绍兴苏泊尔生活电器有限公司 | EMC filter circuit and electromagnetism stove |
| CN206313657U (en) * | 2016-11-02 | 2017-07-07 | 浙江绍兴苏泊尔生活电器有限公司 | EMC filter circuit and electromagnetism stove |
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