EP2284848B1 - Transmitter - Google Patents

Description

The invention relates to a transformer having a primary core with a primary winding, a first secondary core with a first secondary winding and a second secondary core with a second secondary winding.

From the interface technology electronic components, such as modular converters for measurement and control technology, and in particular isolation amplifier known. Such isolation amplifiers can be used for galvanic isolation, conversion, amplification and / or filtering of standard, standard signals and adaptation of analog signals. The isolation amplifiers are often galvanically isolated from each other in the input, output and / or supply circuit. The separation avoids the influence of different sensor and actuator circuits among each other by interrupting the ground loops caused by grounding of the various circuits.

The galvanic isolation is carried out for example by inductive passive components, which have the property to transmit electrical energy. A well-known from the prior art passive device is, for example, the transformer that allows the up or down transforming AC voltages. A transformer, which is not used for energy transmission, but is used for analog information transmission, is referred to in the art as a transformer. Such a transformer can be used for the transmission of energy and / or signals, wherein both aforementioned electronic components according to the same principle of an inductive component function. In many cases, the electronic components of isolation amplifiers, in particular of the transformer, mounted on printed circuit boards, wherein the circuit board is arranged in an insulating material and equipped with screw, plug or spring connection technology. Such Isolierstoffgehäuse can be snapped onto mounting rails to EN 50022 and thus mounted, for example, in cabinets.

The known from the prior art transformers usually have a core and a plurality of windings on the core. In this case, the core is designed, for example, as a magnetic core of a soft magnetic material, that is, for example, a ferrite, while the winding is preferably made of an insulated wire. The output current or the output voltage are determined by the winding ratio in such transformers, which are usually high-impedance, or when designed as current transformers transformers that are usually short-circuited in the output. In many cases, the known from the prior art transformer several secondary windings, so that the output voltage is present at all secondary windings, regardless of whether the output is loaded or not. Each individual output current varies depending on the load and is independent of the load of the neighboring output.

From the DE 10 2005 041 131 a current transformer or transformer is known in which two or more cores are connected to each other by means of a short-circuit or coupling winding to a transformer or current transformer. Two or more windings are wound on the secondary core. As with the other of the prior art

Another transformer is from the US 3,568,035 known. This transformer comprises a primary core with a primary winding, a first secondary core with a first secondary winding and a second secondary core with a second secondary winding, wherein the primary core, the first secondary core and the second secondary core are connected to each other via a short-circuit winding and the outputs of the secondary windings connected in series are, um
known and, for example, above-mentioned transformers, the output currents of the secondary windings of the transformer are the DE 10 2005 041 131 distributed unevenly depending on the initial loads. However, such a non-calculable distribution of the output currents makes such transformers or current transformers unusable for many fields of application.

The invention has for its object to provide a transformer which has at least two outputs that reliably deliver the same power.

The object is achieved according to the invention by the features of the independent claim. Advantageous embodiments of the invention are specified in the subclaims.

Accordingly, the object is achieved by a current transformer having a primary core with a primary winding, a first secondary core with a first secondary winding and a second secondary core with a second secondary winding, wherein the primary core, the first secondary core and the second secondary core are connected to each other via a short-circuit winding and the first secondary winding and the second secondary winding are operated at the same number of turns in a short circuit. According to the invention, a transformer or a current transformer is specified, which provides an input signal at two outputs as "doubler" such that - with the same number of turns of the first secondary winding and the second secondary winding - the same signal is available at both outputs. Surprisingly, it has been found that the transformer according to the invention in a particularly simple manner the provision of the same current at the two outputs allowed, wherein the currents do not divide unevenly, for example due to different loads. Due to the fact that both secondary windings are connected in series, the current in both secondary windings is the same for the same number of turns. For different number of turns of the secondary windings, the output currents of the secondary windings behave in accordance with the ratio of the number of turns of the secondary windings.

In the context of the present invention, input or output is understood to be the primary winding or the first secondary winding and / or the second secondary winding. Accordingly, an input voltage is applied, for example, to the primary winding, while an output voltage is applied to a secondary winding.

The primary core, the first secondary core and / or the second secondary core may be formed as any core for - in cooperation with a winding - arbitrary inductive component. Preferably, the primary core, the first secondary core and / or the second secondary core comprises a magnetic core of a soft magnetic material, but most preferably a ferrite core. The primary winding, the first secondary winding, the second secondary winding and / or the short-circuit winding are / is preferably designed as an electrical conductor, such as a wire, but most preferably as an insulated wire. In principle, any current can be applied to the primary winding, the first secondary winding and / or the second secondary winding. Preferably, however, the transformer is with a current of 0 to 5, 10, 20, 50th and / or 100 mA at the primary winding and / or at a secondary winding.

As mentioned above, the short-circuit winding can be configured as desired. Most preferably, however, the short-circuit winding is self-contained, that is, for example, has a self-contained winding. Furthermore, it is preferred that the short-circuit winding has one, two, five or ten windings.

In principle, the number of turns of the first secondary winding and / or the second secondary winding can be arbitrary. According to a particularly preferred embodiment of the invention, the number of turns of the first secondary winding is equal to the number of turns of the second secondary winding. By such a configuration it is achieved that the currents in the two secondary windings, ie in the first secondary winding and the second secondary winding are the same size, so even with uneven load on the first secondary winding and the second secondary winding is not divided unevenly but the same are.

According to a further preferred embodiment of the invention, the primary core, the first secondary core and the second secondary core each have a center hole, wherein the primary winding, the first secondary winding and the second secondary winding are guided through the respective center hole and the short-circuit winding is passed through the respective center hole. Thus configured, the primary core, the first secondary core and the second secondary core each form an inductive component, wherein the primary core, the first secondary core and the second secondary core preferably comprise a magnetic core of a soft magnetic material and the primary winding, the first secondary winding and the second secondary winding and the short-circuit winding are preferably made of insulated wire. The dimensioning of the primary winding, the first secondary winding, the second secondary winding and / or the short-circuit winding can be carried out with regard to the expected voltages, currents and the number of turns.

In principle, the transmitter may be manufactured as any electrical component in any manner known in the art. According to a particularly preferred embodiment of the invention, however, it is provided that the transmitter has a substrate for provision on a printed circuit board, the substrate has a conductor track and the primary core, the first secondary core and / or the second secondary core can be fastened to the substrate such that the Ladder forms the short circuit winding. This makes it possible to produce a transformer in a particularly space-saving manner with low overall height, which is particularly easy to mount on known from the prior art circuit boards.

Most preferably, the transformer according to the invention is further configured such that the requirements for clearance and creepage distances according to the standards for ensuring intrinsic safety, also called EX standards, are met, such as the standards EN 60079-11 or EN 60079-0, that is, the primary core with the primary winding, the first secondary winding with the first secondary winding, the second secondary core with the second secondary winding and the short-circuit winding according to the EX standards dimensioned and positioned on the substrate. It is also preferred that the Conductor is dimensioned according to the expected currents and / or voltages of the short-circuit winding. It is further preferred that the conductor track is provided within the substrate, so that the substrate forms the insulation for the conductor track. The substrate can also be configured as a circuit board known from the prior art for receiving the primary core and the secondary cores.

According to a further preferred embodiment of the invention, it is provided that a second conductor track is provided on the substrate and / or on the circuit board and the conductor track is connected to the second conductor track for forming the short-circuit winding. Most preferably, a completed short-circuit winding is provided by such a configuration. The provision of a second conductor on the substrate and / or on the circuit board thus allows a particularly simple design of the short-circuit winding.

In principle, the primary winding, the secondary winding, the second secondary winding and / or the short-circuit winding can be contacted with any means known from the prior art. According to a further preferred embodiment of the invention, however, it is provided that the substrate has contact surfaces for contacting the printed circuit board and / or for contacting the primary winding, the first secondary winding, the second secondary winding and / or the short-circuit winding. The contact surfaces may be metallic, for example, so that by soldering, bonding or other known from the prior art means electrically conductive connections between the circuit board, the conductor track, the primary winding, the first Secondary winding, the second secondary winding, the short-circuit winding and / or external contacts can be produced. About such contact surfaces, for example, in a particularly simple manner, an electrically conductive contact to a drive circuit for the transformer can be made.

According to another preferred embodiment of the invention, the substrate has webs for receiving the primary core, the first secondary core and / or the second secondary core, wherein the conductor track is provided in the web. Furthermore, it is preferred that the substrate has two oppositely arranged webs, the primary core is arranged on the first web and the first secondary core and the second secondary core are arranged on the second web. Most preferably, the first web and the second web are arranged spaced from each other. Furthermore, it is preferred that the conductor track of at least 0.5 mm insulating material, so for example, the substrate is surrounded. In this way, the requirements of the EX standards can be realized. Furthermore, by appropriate arrangement of the primary winding, the first secondary winding and the second secondary winding, the necessary to comply with the EX standards distances, and clearance and creepage distances for safe galvanic isolation, be ensured by arranging on oppositely oriented webs. Most preferably, the short-circuit winding is uniformly distributed on both sides of the oppositely disposed webs, resulting in an improved coupling of the inductive components thus formed.

Furthermore, it is preferred that the first secondary winding and the second secondary winding, which preferably on one of the oppositely arranged webs are arranged side by side, isolated by insulation against each other. Such insulation may be embodied, for example, as a circular disk made of a non-conductive material, wherein the insulation preferably has a center hole, so that the insulation can also be arranged on the web as the first secondary core and the second secondary core.

According to another preferred embodiment of the invention, the substrate is designed as a planar substrate and / or the substrate is mountable on the printed circuit board in SMD technology. Furthermore, it is preferable for the substrate to have a suction surface, so that a vacuum suction device can suck in, transport the substrate, position it over the printed circuit board and deposit it. By design in SMD technology, the transformer is realized in a particularly space-saving manner and can also be used in limited space.

According to another preferred embodiment of the invention, the short-circuit winding has at least one winding. Furthermore, it is preferred that the primary core, the first secondary core and / or the second secondary core are each embodied as toroidal cores or as rectangular cores. Very particularly preferred is the use of a transformer according to the invention as a current transformer.

According to another preferred embodiment it is provided that the transformer has at least three secondary cores, each secondary core has a respective secondary winding, and the primary core and the secondary cores are connected to each other via the short-circuit winding. Accordingly, it is therefore preferred that the

Transmitter in addition to the first secondary core and the second secondary core has at least one further secondary core with a respective further secondary winding, wherein the other secondary cores and the primary core, the first secondary core and the second secondary core are also connected to each other via the short-circuit winding. Further embodiments of the other secondary cores or further secondary windings are obtained in analogy to the above.

The invention will be explained in more detail with reference to the accompanying drawings with reference to a preferred embodiment.

Fig. 1

einen erfindungsgemäßen Übertrager gemäß einem bevorzugten Ausführungsbeispiel der Erfindung in einer schematischen Ansicht,

Fig. 2

das Ersatzschaltbild des erfindungsgemäßen Übertragers gemäß dem bevorzugten Ausführungsbeispiel der Erfindung, und

Fig. 3

den erfindungsgemäßen Übertrager auf einem Substrat gemäß dem bevorzugten Ausführungsbeispiel der Erfindung in einer Draufsicht.

Show it

Fig. 1

a transformer according to the invention according to a preferred embodiment of the invention in a schematic view,

Fig. 2

the equivalent circuit of the transformer according to the invention according to the preferred embodiment of the invention, and

Fig. 3

the transmitter according to the invention on a substrate according to the preferred embodiment of the invention in a plan view.

Out Fig. 1-3 is a transformer with a primary core 1 with a primary winding 2, a first secondary core 3 with a first secondary winding 4 and a second secondary core 5 with a second secondary winding 6 visible. The primary core 1, the first secondary core 3 and the second secondary core 5 are connected to each other via a short-circuit winding 7.

Such a transformer or current transformer is used to transmit power or signals galvanically isolated. The number of turns N1, N2, N3 determine the output current I2, I3 or the output voltage U2, U3, depending on the input current I1 or the input voltage U1. In this case, current transformers are usually short-circuited in the output, ie at the secondary winding 4, 6, while voltage transformers are terminated in the high-impedance output.

When using the transformer as a current transformer, as previously stated, the secondary windings 4, 6 operated in a short circuit, so that a primary side impressed current I1 in the secondary circuits I2, I3 can flow. Thus, if a current I1 is impressed into the current transformer on the primary side, it is transformed into the short-circuit winding 7 with the transmission ratio of N1 to NK.

As also from the replacement shield image of the transformer according to the invention in Fig. 2 As can be seen, this transformed current IK flows as a primary current through the other partial transformers, ie the secondary cores 3, 5 with the secondary windings 4, 6, and is transformed down again with the transmission ratio NK to N2 or N3. With the same number of turns of the windings N2 and N3 flow in both secondary windings 4, 6, the same currents I2, I3, because the primary current, ie the short-circuit current IK of the partial transformer, is also the same size.

Surprisingly, it has been found that with the same number of turns of the windings N2 and N3 in the first secondary winding 4 and in the second secondary winding 6, the same currents I2 and I3 flow. The transformer according to the invention or current transformer thus allows the galvanic separation of an input signal U1, I1 to two output signals U2, I2, U3, I3 such that at both outputs of the same current I2, I3 flows and the currents I2, I3 at the same number of turns of Do not divide windings N2 and N3 unevenly.

Fig. 3 shows an integratable into a printed circuit transformer SMD technology according to the invention, wherein the primary core 1, the first secondary core 3 and the second secondary core 5 having a magnetic core of a soft magnetic material, wherein the magnetic core each having a center hole, not shown, through that the primary winding 2, the first secondary winding 4 and the second secondary winding 6 and a short-circuit winding 7 designed as a conductor track are guided. The designed as a conductor short-circuit winding 7 is arranged in a substrate 8.

As further out Fig. 3 can be seen, the substrate 8 webs 9 for receiving the primary core 2, the first secondary core 3 and the second secondary core 5, wherein the conductor track is arranged in the web 9. The primary core 2 is arranged on a first web 9 and the first secondary core 3 and the second secondary core 5 are arranged on a second web 9 at a distance from one another. By such a spacing, ie correspondingly high clearance and creepage distances for reliable electrical isolation of the primary winding 2 and the secondary windings 4, 6 leave to realize the necessary distances to reach the EX standards.

Furthermore, an insulation 10 is provided between the first secondary winding 4 and the second secondary winding 6, wherein the insulation 10 is made of an insulating material.

The substrate 8 also has a second conductor 11, wherein the second conductor 11 and / or provided on the circuit board trace, not shown, for forming the closed short-circuit winding 7 is usable.

For contacting the circuit board and the primary winding 2, the first secondary winding 4, the second secondary winding 6, the short-circuit winding 7 and the second conductor 11 metallic contact surfaces 12 are provided, which in known from the prior art, for example by soldering, with corresponding contacts the circuit board are connectable.

The transformer according to the invention thus allows in a particularly simple and compact design to provide two equal secondary side currents I2, I3, which are the same number of turns of the windings N2 and N3 regardless of the load. LIST OF REFERENCE NUMBERS primary core 1 primary 2 First secondary core 3 First secondary winding 4 Second secondary core 5 Second secondary winding 6 Short circuit winding 7 substratum 8th web 9 isolation 10 Second trace 11 contact area 12

Claims (14)

1. A current transformer having a primary core (1) with a primary winding (2), a first secondary core (3) with a first secondary winding (4), and a second secondary core (5) with a second secondary winding (6), wherein the primary core (1), the first secondary core (3) and the second secondary core (5) are connected to one another via a squirrel-cage winding (7),
   wherein the first secondary winding (4) and the second secondary winding (6) are operated in a short circuit with the same number of turns.
2. The current transformer according to claim 1, wherein the squirrel-cage winding (7) is closed in itself.
3. The current transformer according to either one of the preceding claims, wherein the primary core (1), the first secondary core (3) and the second secondary core (5) each have a central hole, the primary winding (2), the first secondary winding (4) and the second secondary winding (6) are guided through said central holes respectively, and the squirrel-cage winding (7) is guided through the respective central holes.
4. The current transformer according to any one of the preceding claims, wherein the transformer comprises a substrate (8) to be provided on a printed circuit board, the substrate (8) comprises a conductive track, and the primary core (1), the first secondary core (3) and/or the second secondary core (5) can be secured to the substrate in such a way that the conductive track forms the squirrel-cage winding (7) .
5. The current transformer according to claim 4, wherein a second conductive track (11) is provided on the substrate and/or on the printed circuit board, and the conductive track is connected to the second conductive track (11) in order to form the squirrel-cage winding (7).
6. The current transformer according to either one of claims 4 or 5, wherein the substrate (8) has contact faces (12) for contacting the printed circuit board and/or for contacting the primary winding (2), the first secondary winding (4), the second secondary winding (6) and/or the squirrel-cage winding (7).
7. The current transformer according to any one of claims 4 to 6, wherein the substrate (8) has arms (9) for receiving the primary core (1), the first secondary core (3) and/or the second secondary core (5), and the conductive track is provided in the arm (9).
8. The current transformer according to claim 7, wherein the substrate (8) has two oppositely arranged arms (9), the primary core (1) is arranged on the first arm (9) and the first secondary core (3) and the second secondary core (5) are arranged on the second arm (9).
9. The current transformer according to claim 8, wherein the first arm (9) and the second arm (9) are arranged at a distance from one another.
10. The current transformer according to any one of the preceding claims, wherein the first secondary winding (4) and the second secondary winding (6) are insulated with respect to one another by insulation (10).
11. The current transformer according to any one of claims 4 to 10, wherein the substrate (8) is a planar substrate and/or the substrate (8) can be secured on the printed circuit board by means of SMD technology.
12. The current transformer according to any one of the preceding claims, wherein the squirrel-cage winding (7) has at least one winding.
13. The current transformer according to any one of the preceding claims, wherein the primary core (1), the first secondary core (3) and/or the second secondary core (5) are each embodied as ring cores or as rectangular cores.
14. The current transformer according to any one of the preceding claims, having at least three secondary cores (3, 5), wherein each secondary core (3, 5) has a corresponding secondary winding (4, 6), and the primary core (1) and the secondary cores (3, 5) are connected to one another via the squirrel-cage winding (7).

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