DE102017222248A1 - Throttle with current sensor - Google Patents

Abstract

A choke (12), in particular a common mode choke (1), comprising a hollow magnetically soft core (10) having a plurality of recesses for guiding one electrical conductor (22-24), each of the recesses being defined by a projection (121-123), which leads from an outer periphery of the hollow soft magnetic core (10) toward the center (M) of the hollow soft magnetic core (10), is separated from the adjacent recess, and between two of the adjacent projections (121-123) and adjacent to the end portions of these projections (121-123), a current sensor (331-33) is arranged.

Description

The present invention relates to a reactor with current sensor, in particular a common mode choke.

EMC filters (EMC = Electromagnetic Compatibility) are used in power electronics in vehicles to ensure the most trouble-free on-board electrical system. The EMC filter can be used both on the DC side (DC = DC) and on the AC side (AC = AC) of the power electronics. For example, in the case of an inverter that converts the DC energy of the battery to the AC energy on the electric machine, the EMC filter is installed between the inverter and the electric machine to propagate electromagnetic interference toward the electric machine to reduce.

The principle of the output filter can be described in the form of an electrical throttle. The reactor has a soft magnetic core and usually three AC lines (electrical conductors) guided in the interior of the soft magnetic core, which are connected to the electric machine through the soft magnetic core. With this structure, a common mode impedance is generated to reduce the propagation of the common mode noise. At the same time, AC current sensors are used in the inverter to measure the AC currents. The signals of these current sensors are then fed into a microcontroller and further processed there for control or monitoring.

A typical open-loop Hall current sensor is in 1 shown and consists of a Hall sensor 30 and a soft magnetic core 10 , as well as an AC line 21 passing through the soft magnetic core 10 is guided. Based on the current passing through the soft magnetic core 10 flows, can define a defined electromagnetic field in the area of the Hall sensor 30 to be generated.

EMC filters on the AC output of an inverter and the AC current sensors have previously been designed and built separately in the inverter. As a result, both components must have a large space. Due to the soft magnetic material used, the two components are expensive.

Therefore, it is an object of this invention to provide a choke for EMC filters that requires less space and is thus less expensive.

This object is achieved by the features of the independent claim. Advantageous embodiments are the subject of the dependent claims.

Accordingly, a throttle is proposed, comprising a hollow soft magnetic core. The core has a plurality of recesses for guiding each of an electrical conductor. Each of the recesses is separated from the adjacent recess by a protrusion leading from an outer periphery of the hollow soft magnetic core toward the center of the hollow soft magnetic core. Accordingly, such a projection is located between two adjacent recesses. Accordingly, such a recess is located between two adjacent projections. The projections have in the direction of the center of the soft magnetic core (that is, in the direction of radially inward) in each case over an end region. Between at least two of the thus adjacent projections and adjacent to these end portions of these two projections, a current sensor is arranged.

The proposed arrangement, a reduction of the space for the arrangement of current sensors in EMC filters can be achieved. The functions of a throttle and a current sensor are thus combined in a common component.

In particular, the electrical conductors and the current sensor together with the soft magnetic core are components of the throttle. The throttle may also include a housing surrounding the core.

Preferably, the core has exactly or at least three such recesses. Thus, exactly or at least three such electrical conductors are provided. In particular, thus, the throttle can be used in a three-phase or multi-phase inverter. In this case, the electrical conductors then form the phase lines (AC lines) of the inverter. By using three or more such current sensors, the phase currents of all the phase lines can then be determined.

Preferably, a current sensor is arranged in each case between all adjacent two projections in this manner. Thus, exactly or at least three current sensors can be provided. The current sensor is used in particular for determining the electric current in that electrical conductor which is guided in the recess between the two adjacent projections with the intermediate current sensor.

Preferably, the one or more current sensors is offset in the direction of the center of the soft magnetic core to the associated electrical conductor, which is guided in the respective recess. Accordingly, the current sensor (s) are located radially further within the core with respect to the electrical conductors. In particular, when using multiple current sensors, these are arranged on a common radius within the soft magnetic core. In particular, the electrical conductors are arranged or guided on a (other) common radius within the soft-magnetic core.

The projections may each have the shape of a bolt. The protrusions may lead from a radially outer portion of the hollow soft magnetic core cavity to a radially inner portion of the hollow space. Within the cavity and the recesses are then provided. These thus each form part of the cavity. The projections are in particular formed integrally with the soft-magnetic core. They then form an integral part of the hollow core and consist of the same soft magnetic material.

The throttle is preferably an electrical throttle, in particular a common mode throttle. Such a (common mode) choke may be used, for example, in an application in power electronics at the high-voltage input of a power electronic device, such as an electronic ballast. an inverter, between a DC high-voltage connector (DC = DC) and a DC link capacitor may be arranged. Alternatively, as already described above, the throttle may also be arranged at an AC output of an inverter, that is to say at its phase lines (AC lines). The invention can therefore also relate to such an inverter.

Such an electrical conductor may be formed, for example, as a busbar, wire or stranded wire. It consists in particular of a material with a good electrical conductivity, such as copper or aluminum.

Such a soft magnetic core consists of a soft magnetic material. This is understood in particular to mean a ferromagnetic material which can be easily magnetized in a magnetic field. According to DIN EN 60404-1, such a material may in particular be a material which has a coercive field strength of 1000 A / m or less.

In one embodiment, the projections are arranged symmetrically offset from each other in the circumferential direction of the soft magnetic core. If exactly three recesses and correspondingly exactly three projections are provided in a preferred embodiment, these projections are then offset from each other at an angle of 120 degrees. By this arrangement, the electric conductors and the current sensors (if plural are used) are the same distance from each other, and the manufacture of the reactor is simplified due to the symmetry.

In one embodiment, the protrusions have tapered end portions towards the center of the soft magnetic core. Advantageously, in this case the current sensor, preferably each of the current sensors, in the region of the slopes of the tapered end portions of the two adjacent projections arranged. In particular, the current sensor or sensors are then located close to the center of the soft magnetic core.

In one embodiment, the hollow soft magnetic core (at least externally) in the shape of a cylinder. Thereby, the center to which the end portions of the projections point, the center of the cylinder radius. In addition, the production is simplified due to the symmetrical shape.

In one embodiment, the extension (length) of each projection toward the center of the soft magnetic core is smaller than the distance between the outer periphery of the cavity within the core and the center of the soft magnetic core. This ensures that the projections do not touch the center and thus influence the electric field.

In one embodiment, each of the protrusions has at least or exactly one length in the longitudinal direction of the soft magnetic core, which corresponds to the length of the current sensor in the longitudinal direction of the soft magnetic core. In other words, the protrusions and the current sensor or sensors in the longitudinal direction of the core are at least the same length. Thus, material can be saved.

In another embodiment, at least one of the protrusions, preferably each of the protrusions, has a length in the entire length of the soft magnetic core in its longitudinal direction. As a result, the push-pull interference can be further reduced by the increased push-pull impedance.

In one embodiment, the current sensor is designed as a Hall sensor. Hall sensors are insensitive to (non-magnetic) dirt and water, making them very well suited for automotive use.

The current sensors can be placed on a common circuit board. This circuit board can be part of the choke. The electronic components used for the signal processing of the Sensors are needed, such as capacitors and resistors, can also be placed on this common circuit board.

Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures showing details, and from the claims. The individual features can be realized individually for themselves or for several in any combination in a variant of the invention.

• 1 zeigt einen weichmagnetischen Kern mit Hall-Sensor und einer AC-Leitung gemäß dem Stand der Technik.
• 2 zeigt eine Ansicht einer Drossel mit integriertem Strom-Sensor gemäß einer Ausführung der vorliegenden Erfindung.
• 3 zeigt einen Querschnitt der in 2 gezeigten Drossel.

Preferred embodiments of the invention will be explained in more detail with reference to the accompanying figures. Shown schematically in each case:

• 1 shows a soft magnetic core with Hall sensor and an AC line according to the prior art.
• 2 shows a view of a throttle with integrated current sensor according to an embodiment of the present invention.
• 3 shows a cross section of in 2 shown throttle.

In the following description of the figures, the same elements or functions are provided with the same reference numerals.

The core of the invention is to achieve a reduction of the installation space for the arrangement of current sensors in EMC filters and thus to reduce costs.

2 shows a possible embodiment of the invention. Here the invention is based on the example of a common mode choke designed as a cylinder 12 with soft magnetic core 10 and three electrical conductors guided therein 22 . 23 . 24 illustrated. At the electrical conductors 22 . 23 . 24 each is an AC line, so in each case an electrical line for passing an electrical alternating current. The goal is the generation of the common mode impedance for the attenuation of the disturbance and for the current sensors 31 . 32 . 33 necessary magnetic field.

3 shows a cross section of in 2 shown throttle 12 ,

Each of the three electrical conductors 22 . 23 . 24 is in its own designated recess by the cylindrically shaped soft magnetic core in this example 10 the common mode choke 12 guided. The recesses together form a cavity within the soft magnetic core 10 , That is, the inner (hollow) region of the common mode choke 12 is structured so that he has three recesses to guide each exactly one of the ladder 22 . 23 . 24 having.

Each of the recesses is thereby by two projections 121 . 122 . 123 separated from the two adjacent recesses. This means that between two adjacent recesses of one of the projections 121 . 122 . 123 located. And that means being between two adjacent protrusions 121 . 122 . 123 one of the recesses is located. Consequently, for the three recesses exactly three projections 121 . 122 . 123 intended.

The projections 121 . 122 . 123 have a length or extent A in the direction of the center M the cylinder radius (ie radially inward) on. That is, regardless of the external shape of the soft magnetic core 10 each of the projections 121 . 122 . 123 from the outer periphery of the cavity within the hollow core 10 in the direction of the center M of the core 10 is guided. The center will also be the center M when the soft magnetic core 10 is designed as a cylinder.

The projections 121 . 122 . 123 are, as shown, preferably at an angle of 120 degrees in the circumferential direction of the core 10 arranged offset from one another. This facilitates the production of the throttle due to the symmetry 12 ,

The projections 121 . 122 . 123 advantageously point in the direction of the center M of the soft magnetic core 10 pointed end portions on. Thus, the projections have 121 . 122 . 123 in cross section in each case a kind of arrow shape, as in 2 and 3 clear to see.

The current sensors required for current measurement 31 . 32 . 33 are preferably Hall sensors. The current sensors 31 . 32 . 33 are each one of the electrical conductors 22 . 23 . 24 assigned. Each of the current sensors 31 . 32 . 33 is located in the region of the recess of the associated electrical conductor 22 . 23 . 24 inside the cavity of the core 10 , The current sensors 31 . 32 . 33 are thus also each in the associated electrical conductor 22 . 23 . 24 associated recess disposed, ie between each two of the projections 121 . 122 . 123 , The current sensors are preferred 31 . 32 . 33 arranged in the region of the slopes of the tapered ends of the recesses and thus close to the center M of the cylinder, as in 3 clearly visible.

The shape and size of the recesses is chosen such that the electrical conductors 22 . 23 . 24 and the associated current sensors 31 . 32 . 33 find enough space in it, and that the current sensors 31 . 32 . 33 the electrical currents in the conductors 22 . 23 . 24 can measure in a suitable manner.

As in 3 is seen along and inside the circumference of the soft magnetic core 10 due to the common mode current of the three electrical conductors 22 . 23 . 24 generates a magnetic field. This is in 3 through the two dashed lines, the concentric circles around the center M form, represented. This creates a common mode impedance.

The in the electrical conductors 22 . 23 . 24 flowing currents also generate a magnetic field, but essentially only by the two adjacent projections 121 . 122 . 123 of the respective leader 22 . 23 . 24 is directed. This is in 3 through the dotted-dashed line around the ladder 22 shown by way of example. This magnetic field is in this example by the projections 121 and 122 directed and from the associated current sensor 31 detected. The current sensor 31 generates a corresponding signal for a (not shown) microcontroller.

As in 3 can also be seen, touching the separation of the recesses and thus the electrical conductor 22 . 23 . 24 and current sensors 31 . 32 . 33 provided projections 121 . 122 . 123 not the focus M of the soft magnetic core 10 , Accordingly, their end regions have a certain distance (air gap) to each other. Therein are the current sensors 31 . 32 . 33 arranged.

The shape, the length / extension A the projections 121 . 122 . 123 towards the center M of the soft magnetic core 10 , the length of the projections 121 . 122 . 123 longitudinal L of the soft magnetic core 10 , as well as the width of the projections 121 . 122 . 123 in the circumferential direction is chosen so that the magnetic fields through the electrical conductors 22 . 23 . 24 and the associated current sensors 31 . 32 . 33 be generated and performed in the intended manner.

The projections 121 . 122 . 123 in the soft magnetic core 10 can be designed so that they are only in the area of Hall sensors 31 . 32 . 33 are present, ie not along the entire length L of the soft magnetic core 10 the throttle 12 , In this embodiment, material and thus costs can be saved.

Alternatively, the projections 121 . 122 . 123 along the entire length L of the soft magnetic core 10 the throttle 12 be educated. In this embodiment, in addition, the push-pull interference can be further reduced because with the projections 121 . 122 . 123 a push-pull impedance can be generated.

The proposed common mode choke 12 can be used in particular in an EMC filter of an inverter in the automotive sector, ie for motor vehicles. It is not limited to this application.

LIST OF REFERENCE NUMBERS

10

soft magnetic core

12

throttle

22-24

electrical conductor

31-33

Flow sensor

121-123

head Start

A

Extension / length of a projection

L

Length / longitudinal direction of the throttle

M

Focus

Claims (9)

Choke (12), in particular common mode choke (1), comprising a hollow magnetically soft core (10), having a plurality of recesses for guiding each of an electrical conductor (22-24), wherein each of the recesses is separated from the adjacent recess by a projection (121-123) leading from an outer circumference of the hollow soft magnetic core (10) toward the center (M) of the hollow soft magnetic core (10), and wherein between two of the adjacent projections (121-123) and adjacent to the end portions of these two projections (121-123), a current sensor (331-33) is arranged. Throttle (12) after Claim 1 , wherein the projections (121-123) are arranged offset in the circumferential direction of the soft magnetic core (10) symmetrically to each other. A choke (12) according to any one of the preceding claims, wherein the projections (121-123) have tapered end portions towards the center of the soft magnetic core (10). Throttle (12) after Claim 3 wherein the current sensor (31-33) is disposed in the region of the slopes of the tapered end portions of two of the projections (121-123). A choke (12) according to any one of the preceding claims, wherein the hollow soft magnetic core (10) is in the shape of a cylinder. A choke (12) according to any one of the preceding claims, wherein the extension (A) of each projection (121-123) toward the center (M) of the soft magnetic core (10) is smaller than the distance between an outer periphery of the cavity inside the hollow soft magnetic core (10) and the center (M). A choke (12) according to any one of the preceding claims, wherein each of the protrusions (121-123) has a length in the longitudinal direction (L) of the soft magnetic core (10) corresponding to the length of the current sensor (31-33) in the longitudinal direction (L ) of the soft magnetic core (10). A choke (12) according to any one of the preceding claims, wherein at least one of the protrusions (121-123) has an entire-length length of the soft magnetic core (10) in the longitudinal direction (L) thereof. Throttle (12) according to one of the preceding claims, wherein the current sensor (31-33) is designed as a Hall sensor.

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