CN104813176A - A SMD current sensor device and uses thereof - Google Patents

Abstract

A SMD current sensor device comprises a magnetic core, a first (31) and a second (43), the first (31) and the second (32) windings respectively wound around a first and a second section of the magnetic core. Most of the first winding (31) is over moulded with an electrically insulating material defining a first envelope (3) defining a through hole (33) for the introduction therein of the first section of the magnetic core. The device also comprises an electrically insulating support (44) around which the second winding (43) is wound and which defines a through hole (42) for the introduction therein of the second section of the magnetic core, both through holes (33, 42) being aligned to each other. The uses of the SMD current sensor device are for sensing an excess of electrical current circulating through the first winding and for accurately measuring the magnitude of said electrical current.

Description

SMD current sensor equipment and its application

technical field

A first aspect of the invention relates generally to an SMD (Surface Mount Device) current sensor device (device), i.e. a device designed to be arranged by SMD technology and soldered on a printed circuit board, the device comprising a wound Two windings on a magnetic core, more specifically related to SMD current sensor devices that are structurally formed to constitute small and compact, inter alia by means of an electrical insulation barrier between the two windings (which allows the two windings placed close to each other) to provide high efficiency.

The second and third aspects of the invention relate to different applications of the SMD current measuring device of the first aspect.

Background technique

There are various devices related to current sensor devices in the prior art, some of which include current transformers (also called transformers) for measuring current, such as the device disclosed in US Pat. No. 4,630,218.

Furthermore, it is well known to have switching protection systems including such current sensors in today's power supplies, such as in the power line current fed power supplies disclosed in US Patent Application Publication No. US 2012236611 A1 like that.

In applications such as inverters and DC/DC battery chargers for electric and hybrid vehicles (aka HEV: "Hybrid-Electric Vehicle"), current sensors are required to occupy as little space as possible and support maximum possible electricity. Additionally, to have proper switching management, digital control is required over traditional PWM control and is implemented by sampling the current through the conductor at a very high frequency (between 70KHz and 200KHz).

Due to size limitations, most sensors known in the art are difficult to use in applications that require the sensor to be a surface mount device. The regulations of various international standards regarding the distance between the windings, the distance between the magnetic core and the individual windings etc. prevent the use of conventional devices for this purpose.

However, certain current sensor devices are known that are actually suitable for SMDs, such as the current sensor devices disclosed in the patents cited below.

US Patent US 7622910 B2 discloses an integrated current sensor device suitable for surface mounting, comprising a magnetic core and first and second windings wound around respective first and second sections of the magnetic core.

Patent US 7622910 B2 describes that the magnetic core and its windings are suitably insulated, but does not disclose the special structural arrangement of said elements (winding and magnetic core) to achieve this insulation, nor does it disclose the use for their integration The specific structural setup of the assembly within the substrate of the device, but only references the integrated circuit "Sentron CSA-1V-SO" (which is said to be modified by being included in the AC inductor), so it is implicitly envisaged that it passes through The substrate of the integrated circuit itself or of other layered elements added during its manufacture to provide insulation for the windings and core.

The use of integrated circuit fabrication processes to fabricate the devices described in US 7622910 B2 suffers from a number of disadvantages, including those associated with the cost and inherent limitations and complexities of such processes. In addition, due to thermal, geometric and other constraints, the maximum electrical value that an integrated current sensor device can withstand is lower than that of a non-integrated current sensor device.

EP 1105893 B1 discloses a process for the manufacture of an inductive element comprising molding molten hot melt adhesive under pressure in a metal mold enclosing a magnetic coil wound by one or more windings. core. As an example, the inductive element disclosed in EP 1105893 B1 can be directly adapted to SMDs, according to it, by providing a plurality of blind holes in the mold and placing connections in which one or more windings are formed.

In EP 1105893 B1 no intermediate insulation is disclosed at all between the windings or between the windings and the magnetic core, once the windings are wound on the magnetic core, the disclosed forming process is carried out.

Contents of the invention

The object of the present invention is to provide an alternative to the prior art and to provide an SMD current sensor device which provides a special structural arrangement for its internal components, namely the magnetic core and the winding, which enables The device has increased efficiency due to being manufactured as a compact and small device and meets various international standards regarding insulation standards (e.g. dielectric strength) and/or physical construction standards (e.g. creepage distances, clearances, insulation passage distances) requirements.

To achieve this object, the present invention relates to an SMD current sensor device comprising:

magnetic core;

a first winding around at least a first section of the magnetic core; and

a second winding around at least a second section of the magnetic core;

Contrary to the SMD current sensor devices disclosed in the prior art, in a solution proposed by the present invention, at least a part of the first winding is overmoulded by an electrically insulating material, which defines a first cladding portion ( envelope) that confines the aforementioned at least a portion of the first winding therein, said first wrapping portion defining a through hole for introducing the first section of the magnetic core therein, and the SMD current sensor The device comprises an electrically insulating support around which the second winding is wound and which defines a through hole for introducing the second section of the magnetic core therein, wherein all of the first and second windings The through holes are aligned with each other.

The first cladding provides an insulating physical barrier that physically separates the first winding from the second winding. This barrier provides higher electrical isolation, allowing the distance between the two windings to be reduced due to the increased electrical isolation between the two windings compared to the case where no windings are overmolded with insulating material. Small.

Accordingly, the present invention provides a current sensor device whose arrangement enables the combination of a current sensor with SMD device dimensions, maintaining safety characteristics and complying with the parameters set forth in standards such as IEC-61558 and UL-1950 .

Preferably, the magnetic core and the first and second windings form a current transformer, wherein the first winding acts as the primary winding of the current transformer and the second winding acts as the secondary winding, although for less preferred embodiments this may not be Implemented as a current transformer (for current sensing), but can also be implemented by using the magnetic core and windings of the device of the invention.

As an embodiment, the electrically insulating supporting part is attached to the first covering part, that is, the electrically insulating supporting part and the covering part are two independent parts attached to each other, and as another embodiment, the electrically insulating supporting part Formed in one piece with the first cladding, ie both constitute a single piece.

As an embodiment, the magnetic core comprises at least one elongated magnetic member comprising said first and second sections.

While in one embodiment said first and second sections correspond to distinct regions of a single-piece elongated magnetic member, in another embodiment the core is divided into first and second sub-cores, The first and second magnetic sub-cores include respective elongated magnetic members having free ends abutting each other within said aligned through-holes to form said elongated magnetic member, wherein each elongated magnetic member Said elongated magnetic members correspond to respective said first and second sections of the magnetic core.

Preferably, the core is detachably attached to the first cladding of the first winding, and to the electrically insulating support department.

As another embodiment, the SMD current sensor device of the present invention comprises a first support element and a second support element, each support element supporting said elongated magnetic member at a respective end opposite to said free end. shaped magnetic components.

As an example, said first and second support elements are part of said first and second magnetic sub-cores respectively, and together with corresponding elongate magnetic parts forming respective one-piece (monolithic) elements Formed in one piece and form a closed magnetic circuit when assembled together.

As a preferred embodiment, each said magnetic one-piece element is an E-shaped piece viewed in cross-section through its three legs, and on which the magnetic flux will circulate, with the legs of the central portion The width is twice the width of each side leg so that when two E-shaped pieces are placed facing each other with the free ends of their respective arms/legs in contact, a closed magnetic circuit is formed, wherein the center leg is formed by The magnetic flux density generated by the first/primary winding returns via both sides with half the inductance leg.

As an alternative embodiment, said first and second support elements are non-magnetic elements attached to the elongate magnetic parts of the first and second sub-cores respectively.

As a preferred embodiment, the first winding is configured as one turn, while the second winding is configured as multiple turns. More specifically, in applications in the HEV industry, the second winding is configured with at least fifty turns.

The second winding is also insulated with an electrically insulating material. As an example, the second winding can also be overmolded.

Said insulation or overmolding are independent of each other, i.e. both are performed at least in a separate manner, and both increase the physical barrier between the windings and between the windings and the magnetic core, making the SMD current sensor device of the present invention easy to Withstands higher currents, thereby limiting the possibility of arcing.

According to one embodiment, the magnetic core consists of manganese zinc alloy or amorphous cobalt.

According to one embodiment, the electrically insulating support of the second winding is a winding form around which the second winding is formed.

As an example, the winding die is made of liquid crystal polymers or other materials that meet the requirements of SMD soldering processes such as reflow or vapor phase soldering methods (i.e. high thermal index plastics according to IEC85 standards) and also meet self-extinguishing standards according to UL94 standards. Plastic material composition.

As an embodiment, the first winding comprises copper, nickel, silver, gold and/or tin alloy.

As a preferred embodiment, the principle of the current sensor of the invention is based on the use of meter transformers. Thus, instead of operating on the current through the conductor, measurements are performed from the magnetic field in the core induced by said current.

The second aspect of the present invention relates to the application of the SMD current sensor device in the first aspect for sensing whether the current flowing through the first winding is too large, for example for overheating protection.

Furthermore, in addition to providing a current sensor device for sensing excess current, the present invention can also be used for current measurement. This type of measurement allows the measurement of very high currents without direct contact with this current, which would require considerable bulk for the associated equipment.

Therefore, a third aspect of the invention relates to the use of the SMD current sensor device of any preceding claim for the accurate measurement of the magnitude of the current flowing through the first winding, for example in the control loop of an associated switching power supply Use a reading device (reading).

Description of drawings

These and other advantages and features will be better understood from the following detailed description of embodiments with reference to the accompanying drawings, which should be considered as illustrative and not restrictive, in which:

1 is a perspective view showing an SMD current sensor device of a first aspect of the present invention as an embodiment;

Figure 2 is a top view of the device of Figure 1;

As the same embodiment as Fig. 1 and Fig. 2, Fig. 3 is a three-dimensional exploded view of the device of the first aspect of the present invention;

FIG. 4 shows some elements shown in FIG. 3 in a perspective view, in particular those elements comprising a first winding and a second winding;

Figure 5 shows the same elements as in Figure 4 in top view, with three aligned through-holes for inserting the magnetic core drawn in dashed lines;

Fig. 6 is a sectional view taken along the section line VI-VI of Fig. 5;

Fig. 7 is a sectional view taken along section line VII-VII of Fig. 5;

FIG. 8 is a cross-sectional view taken along the section line VIII-VIII of FIG. 5; and

Fig. 9 is a perspective view showing all the elements shown in Fig. 3 (except the cover 2) after assembly.

Detailed ways

Accompanying drawing shows a plurality of different elements of SMD current sensor device 1 of the present invention, as an embodiment, this device comprises (mainly as shown in Figure 3):

a magnetic core, which is divided into a first sub-core (magnetic sub-core) and a second sub-core, the first sub-core and the second sub-core each comprising an elongated magnetic part 511, 521;

The first winding 31 is overmoulded from an electrically insulating material that defines a first cladding portion 3 that surrounds most of the first winding 31 (except for the free ends 31a and 31b ). ) is limited therein (as shown in FIG. 6), and the first cladding portion 3 defines a through hole 33 for introducing an elongated magnetic component 511 therein, as shown in FIG. 6;

an electrical insulating support 44; and

The second winding 43 is wound around the electrically insulating supporting part 44 , and the electrically insulating supporting part 44 defines a through hole 42 for introducing the elongated magnetic part 521 therein (as shown in FIG. 7 ).

Furthermore, as the illustrated example, the first winding 31 consists of a single turn, while the second winding 43 may comprise 50 to 200 turns. As other examples, those skilled in the art will be able to calculate the ratio of the number of turns of the first and second windings.

As shown in FIG. 8 , the through holes 33 , 42 are aligned with each other such that when the two elongate magnetic members 511 , 521 are inserted through their free ends, they abut each other within the aligned through holes 33 , 42 . These elongated magnetic components 511 , 521 may be attached to the inner contours of the through-hole windings 33 and 42 by structural adhesive or epoxy glue.

(The device) is provided with a cover 2 to house and hold together (here a snap fit) the different elements of the current sensor device 1 , in particular the sub-core, as shown in FIGS. 1 and 2 .

As shown in Figure 3, the SMD current sensor device 1 includes a first support element 51 and a second support element 52, each support element has two parallel arms 51a-51b interconnected by cross beams (traverse) 51c, 52c; 52a- 52b, one of the elongated magnetic members 511, 521 is connected to this beam at the corresponding end opposite its free end, so that the elongated magnetic members 511, 521 are parallel in the same direction as the parallel arms 51a-51b; 52a-52b extending so as to form an E-shaped piece with these parallel arms and corresponding beams 51c; 52c. The two E-shaped pieces are arranged to face each other and when assembled (as shown in FIG. 9 ) at the respective free ends of their respective arms 51a-51b; 52a-52b and elongated magnetic members 511, 521 touch.

These E-shaped shapes of the first support element 51 and the second support element 52 provide a particularly advantageous embodiment because, in final assembly, the shape of the two E-shaped pieces, which are in contact with each other once assembled, approximates that of a typical surface mount device. Cubic or rectangular prisms. And thus, these E-shapes allow to form a symmetrical device 1 and to easily remove the magnetic core for replacement if required.

As a preferred embodiment, the first supporting element 51 and the second supporting element 52 are part of the first sub-core and the second sub-core respectively, and are connected with the corresponding (with which the corresponding magnetic one-piece element is formed together) The elongated magnetic members 511, 521 are formed in one piece, each magnetic one-piece element being an E-shaped piece (as shown in FIG. 3 ) with a central leg 511, 521 of width Wc, which is the width of each side Twice the width Ws of the legs 51a, 51b, 52a, 52b, so that when two E-shaped pieces are arranged to face each other and touch at the free ends of their respective arms/legs, a closed magnetic circuit is formed , where the magnetic flux generated by the first/primary winding 31 in the central leg (formed by 522 plus 521 ) returns with half the inductance value via the two side legs (51a plus 52a and 51b plus 52b).

As another example, the first support element 51 and the second support element 52 are non-magnetic elements attached to the elongate magnetic parts 511 , 521 of the first and second magnetic sub-cores, respectively.

As shown in Figure 3, the present invention provides a single package for each winding 31, 43 so there is a physical barrier between the two to prevent arcing or loss. This is especially beneficial since the device of the present invention is preferably used in applications that withstand 100 to 1000V and have RMS currents (to detect/measure currents up to 50A).

This single package includes a fully overmolded primary winding with a dielectric strength between 2 and 4kV and a creepage distance of at least 5mm from the secondary winding as well as the core, thus meeting requirements such as IEC- Insulators specified and required by standards such as 61558 and UL-1950.

FIG. 4 shows in detail the device of FIG. 3 without the magnetic core and cover 2, so that details of the windings 31, 43 and elements associated therewith, such as the first insulating cladding 3 and the electrically insulating support 44, can be observed. Or the winding mold, in a specific preferred embodiment, the winding mold is formed by liquid crystal polymer (also known as LCP, "Liquid Crystal Polymer"), carbolic acid or any other material and flame retardant resistant to high temperature. This winding die 44 must be able to withstand continuous temperatures between about -40°C and +155°C.

Figure 5 shows a top view of the element shown in Figure 4, where two of the five pins (pin) 41 (the second and fourth in the row of five pins) are connected (not shown in the figure) connected) to the free end of the second or secondary winding 43 on which, when used, an output current proportional to the current through the first or primary winding 31 will be obtained by the principle of electromagnetic induction. As an illustrated example, the winding form 44 of the secondary winding 43 is mechanically connected to five pins 32 to provide better mechanical fastening, however these pins 32 have an indirect electrical connection.

The first winding 31 is a planar metal strip (as shown in FIGS. 1 to 9 ) with free ends 31 a , 31 b that are not overmolded and held outside the cladding 3 , these free ends constitute SMD use to be electrically connected (by soldering) to corresponding circuit board traces to allow current to pass therethrough.

FIG. 6 is a cross-sectional view taken along the section line VI-VI of FIG. 5 and shows how the first winding 31 is embedded into the first cladding portion 3 after being formed to have an Ω-shape or the like, which Ω-shape typically Used to define a regular shape, such as that used for metal profiles.

This omega-shape allows for the formation around the elongated magnetic member 511 where electromagnetically one turn is understood here as a turn.

As shown in FIGS. 5 and 6 , the first cladding portion 3 comprises two upper planar walls 3a, 3b and a protruding central portion 3c surrounding the central portion of the first winding 31 therebetween.

When assembled (as shown in FIG. 9 ), the two parallel arms 51a-51b of the first support member 51 are respectively supported on one of the two upper planar walls 3a, 3b and on the protruding center portion 3c. on the respective adjacent side walls 3c1, 3c2, thus contributing to the general structural robustness of the device 1.

The primary winding is preferably provided to support a DC current of about 50A RMS, so it is preferred to choose a cross-section of about 3 x ^0.4mm2 , a material such as copper plus nickel flash (flash smelting), tin alloy, Silver or gold to ensure that it can be soldered properly and to ensure good electrical properties (ohmic resistivity) and thermal properties (thermal conductivity).

Additionally, the frequency operating range must be between approximately 10KNz to 250KHz to meet industry requirements.

The metal strip forming the first winding 31 is obtained by conventional processes of punching and bending, and is usually formed of stainless steel.

FIG. 7 shows a cross-sectional view taken along section line VII-VII of FIG. 5, which shows how the electrically insulating support 44 (also called winding die) defines the above-mentioned through-holes aligned with the through-holes 33. 42.

Said Figure 7 together with Figures 3, 4 and 5 show an electrically insulating support 44 attached to or integrally formed with a support 4 having two upper planar surfaces 4a, 4b and a central arcuate portion 4c between them and having a central through-hole 55 aligned with the through-holes 33, 42, wherein the two parallel arms 52a-52b of the second support element 52 are respectively supported on said two This likewise contributes to providing the overall structural robustness of the device 1 on the upper planar surfaces 4a, 4b and on the respective adjacent side walls 4c1, 4c2 of the central arcuate portion 4c. This insulating support 44 is used to carry the second or secondary winding 43 .

For the embodiment of FIG. 8 , the electrically insulating support 44 , the support 4 and the first cladding 3 are constructed as a one-piece element whose respective through-holes 55 , 42 and 33 form a single, common through-hole.

A concave region R1 is defined on the upper surface of the support 4 passing under the central arch to serve as a guide for the elongated magnetic member 521 to be easily inserted through the through holes 55 and 42 . For the same purpose, another recessed region R2 is defined on the upper surface of the first cladding portion 3 , as shown in FIG. 5 .

Metal pins 41 for SMD soldering are mechanically attached to said support 4 such that they extend as shown in all figures. It was discussed above that at least two of said metal pins 41 are connected to the free ends of the second winding 43 .

Claims (22)

1. a SMD current sensor devices, comprising:

Magnetic core;

First winding (31), is at least wound around first section of described magnetic core; And

Second winding (43), is at least wound around second section of described magnetic core;

It is characterized in that, described first winding (31) Overmolded by electrically insulating material at least partially, to limit the first covering portion (3), the described of described first winding (31) is limited in this first covering portion by this first covering portion at least partially, described first covering portion (3) is defined for first of described magnetic core section introducing through hole (33) wherein, and wherein said SMD current sensor devices comprises electrical isolation support sector (44), described second winding (43) is wound around described electrical isolation support sector, and described electrical isolation support sector is defined for second of described magnetic core section introducing through hole (42) wherein, the through hole (33) of wherein said first winding (31) and the through hole (42) of described second winding (43) are in alignment with each other.

2. SMD current sensor devices according to claim 1, wherein said electrical isolation support sector (44) is attached to described first covering portion (3), or is integrally formed with described first covering portion (3).

3. SMD current sensor devices according to claim 1 and 2, wherein said magnetic core comprises at least one microscler magnetic component, and described microscler magnetic component comprises described first section and second section.

4. SMD current sensor devices according to claim 3, wherein said magnetic core is divided into the first sub-magnetic core and the second sub-magnetic core, described first sub-magnetic core and the second sub-magnetic core comprise respective microscler magnetic part (511,521), the free end of described microscler magnetic part separately abuts one another in the through hole (33,42) of described alignment, to form described microscler magnetic component, wherein each described microscler magnetic part (511,521) is corresponding to described accordingly first section of described magnetic core and second section.

5. SMD current sensor devices according to claim 4, comprise the first support component (51) and the second support component (52), each described support component supports a described microscler magnetic part at the respective end place contrary with described free end of described microscler magnetic part (511,521).

6. SMD current sensor devices according to claim 5, wherein said first support component (51) and the second support component (52) are a part for described first sub-magnetic core and the second sub-magnetic core respectively, and form as one with corresponding described microscler magnetic part (511,521), to form corresponding one-piece member with corresponding described first support component and the second support component.

7. SMD current sensor devices according to claim 5, wherein said first support component (51) and the second support component (52) are the non-magnetic component of the microscler magnetic part (511,521) being attached to the first sub-magnetic core and the second sub-magnetic core respectively.

8. the SMD current sensor devices according to claim 6 or 7, wherein said first support component (51) and the second support component (52) have by crossbeam (51c separately; 52c) interconnective two parallel arms (51a-51b; 52a-52b), described microscler magnetic part (511,521) is connected to described crossbeam (51c; 52c), described microscler magnetic part edge and described parallel arms (51a-51b is made; 52a-52b) identical direction extends abreast, with described parallel arms and described crossbeam (51c; 52c) form E shaped piece together, wherein two E shaped piece are set to facing with each other, and at both respective described arm (51a-51b; 52a-52b) and described microscler magnetic part (511,521) free end place contact.

9. SMD current sensor devices according to claim 8, wherein said first covering portion (3) comprises at least two upper flat and to face the wall and meditate (3a, 3b) and therebetween outstanding central part (3c), described outstanding central part around described first winding (31) at least partially, at least two upper flat described in two parallel arms (51a-51b) of wherein said first support component (51) are supported on respectively are faced the wall and meditated (3a, one of 3b) upper and be supported on the adjacent wall (3c1 of correspondence of described outstanding central part (3c), 3c2).

10. SMD current sensor devices according to claim 9, wherein said electrical isolation support sector (44) is attached to support member (4) or forms as one with support member (4), described support member (4) has at least two upper flat surface (4a, 4b) and therebetween central dome portion (4c), described central dome portion with described through hole (33, 42) central through hole (55) alignd, at least two upper flat surface (4a described in described two parallel arms (52a-52b) of wherein said second support component (52) are supported on respectively, one of 4b) upper and be supported on the adjacent wall (4c1 of correspondence of described central dome portion (4c), 4c2).

11. SMD current sensor devices according to claim 10, comprise the metal pins (41) for SMD welding, the free end being at least electrically connected to described second winding (43) at least partially of wherein said metal pins (41) and be attached mechanically to described support member (4).

12. SMD current sensor devices according to any one of the claims, the free end (31a, 31b) of wherein said first winding (31) is not wrapped by shaping and remains on outside described covering portion (3), and is configured for two corresponding metal pins of SMD welding.

13. SMD current sensor devices according to claim 1, wherein said first winding (31) is constructed to single turn, and described second winding (43) is constructed to multiturn.

14. SMD current sensor devices according to any one of the claims, wherein said second winding (43) also adopts electrically insulating material Overmolded.

15. SMD current sensor devices according to any one of the claims, wherein, by introducing first section and second section of described magnetic core respectively via the described through hole (33,42) of alignment, described magnetic core is made to be detachably attached to first covering portion (3) of described first winding (31) and the electrical isolation support sector (44) of described second winding (43).

16. SMD current sensor devices according to any one of the claims, wherein said magnetic core is made up of MnZn alloy and/or amorphous cobalt.

17. SMD current sensor devices according to claim 1, the electrical isolation support sector (44) of wherein said second winding (43) is winding former.

18. SMD current sensor devices according to claim 17, wherein said winding former is made up of the material comprising liquid crystal polymer.

19. SMD current sensor devices according to any one of the claims, wherein said first winding (31) comprises nickel, silver, gold and/or ashbury metal.

20. SMD current sensor devices according to any one of the claims, wherein said magnetic core and the first winding (31) and the second winding (43) form power pack.

The application of 21. 1 kinds of SMD current sensor devices according to any one of the claims, excessive for sensing the electric current flowing through described first winding.

The application of 22. 1 kinds of SMD current sensor devices according to any one of claim 1 to 20, flows through the size of the electric current of described first winding for Measurement accuracy.