Improved inductive position sensor

Abstract

The present invention relates to an inductive position sensor (1) for a rotary electric machine, comprising a printed circuit board (10), with two substrates (13, 14), on which there are arranged at least one emitting element (11) intended to emit an oscillating magnetic field towards a coupling element (20) that is rotating in order to generate a modified magnetic field, and at least one receiving device (12) intended to detect the modified magnetic field, the connections connecting the at least one emitting element and the at least one receiving element to at least one signal processing element being provided by conductive elements (101, 102) located in a region (30) different from the region (40) where the emitting (11) and receiving (12) elements are located, the sensor comprising a ground plane (17) positioned on the region (30) of the conductive elements in such a way as to extend up to the region (40) of the emitting (11) and receiving (12) elements.

Description

[0001] Description

[0002] Title of the invention: Improved inductive position sensor

[0003] The present invention relates to the field of position sensors, and more particularly to an inductive position sensor.

[0004] Inductive position sensors, known as eddy current sensors, use an oscillating magnetic field to determine the angular position of a rotating target that forms a coupling element.

[0005] These position sensors are used in particular in electric motors of electric or hybrid vehicles comprising a rotor rotating relative to a stator.

[0006] The angular position of the rotor is determined relative to the stator. The target is mounted at the end of or across a rotor shaft to modify an oscillating magnetic field transmitted by a transmitter. The target is centered relative to an axis of rotation of the rotor. The target comprises several blades that provide a magnetic field pattern relative to the rotor's axis of rotation.

[0007] The position sensor is mounted fixed relative to the stator, facing the target and around or facing the end of the rotor. The position sensor comprises a printed circuit board (PCB) comprising at least one transmission element intended to transmit an oscillating magnetic field towards the target, generating a modified oscillating magnetic field at a given frequency.

[0008] The printed circuit comprises at least one receiving device for detecting the modified oscillating magnetic field and transmitting it to a signal processing unit provided on the printed circuit to deduce the angular position of the target. Typically, the coupling element has an outer diameter substantially identical to the outer diameter of the transmitting antennas.

[0009] However, in some cases, the sensor has to be positioned facing different coupling elements, for example with an outer diameter greater than the outer diameter of the transmitting / receiving antennas. A disadvantage of this situation comes from the fact that when the coupling element is larger than the transmitting and receiving elements, there are significant disturbances during the angle measurement which degrades the performance. For sensors with only two substrate layers forming the electronic board, due to their configuration, the ground plane cannot be sufficiently extended to correct the disturbance problems. Indeed, the ground plane cannot overlap certain electrical connections, for example the conductive elements connecting the transmitting and / or receiving elements to the signal processing unit.Thus, in cases where the coupling element has a larger outer diameter than that of the antennas, the conductive elements behave as a disturbing element in the angle measurement.

[0010] The present invention therefore aims to overcome one of the drawbacks of those of the prior art by proposing a position sensor whose configuration is improved to limit disturbances and improve performance.

[0011] For this purpose, the present invention proposes an inductive position sensor for a rotating electrical machine comprising a printed circuit board, with two substrates, on which are arranged at least one transmitting element intended to transmit an oscillating magnetic field towards a rotating coupling element to generate a modified magnetic field, and at least one receiving device intended to detect the modified magnetic field, the connections between the at least one transmitting element and the at least one receiving element to at least one signal processing element are made with conductive elements located on a zone different from that where the transmitting and receiving elements are located, the sensor comprising a ground plane positioned on the zone of the conductive elements so as to extend to the zone of the transmitting and receiving elements.

[0012] Thus, with the sensor according to the invention, when the coupling element superimposes the area of ​​the conductive elements, the conductive elements being included in the ground plane, without being covered, they no longer behave as disturbing elements.

[0013] According to one embodiment of the invention, the ground plane is segmented into several portions arranged so as to surround the conductive elements without covering them.

[0014] According to one embodiment of the invention, the ground plane is arranged on two substrate layers.

[0015] According to one embodiment of the invention, different portions of the ground plane are arranged on the first and second substrate layers and are connected to each other with metal vias passing through the printed circuit board in its thickness to join another lower substrate.

[0016] According to one embodiment of the invention, a portion of conductive elements located on two different substrate layers of the electronic card are superimposed on each other.

[0017] According to one embodiment of the invention, a portion of conductive elements located on two different substrate layers of the electronic card are arranged so as not to overlap one another.

[0018] The invention also relates to an electrical machine comprising a sensor according to the invention.

[0019] According to one embodiment of the invention, the rotating electrical machine is an electric motor of an electric or hybrid vehicle comprising a rotor rotating relative to a stator.

[0020] The invention also relates to the use of the sensor according to the invention for measuring the angular position of a rotor relative to a stator of an electrical machine.

[0021] Other aims, characteristics and advantages of the invention will be better understood and will appear more clearly on reading the description given below, with reference to the appended figures, given by way of example and in which:

[0022] - [Fig. 1] is a schematic representation of a sensor with two different coupling elements, a) identical diameter b) larger diameter, than the outer diameter of the transmitting antennas,

[0023] - [Fig. 2] is a view of the superposition of the 2 substrate layers of the sensor according to a first embodiment of the invention,

[0024] - [Fig. 3] is a view of portions of a substrate layer of the sensor according to a second embodiment of the invention,

[0025] - [Fig. 4] is a view of portions of another substrate layer of the sensor according to a second embodiment of the invention,

[0026] - [Fig. 5] is a view of the superposition of the 2 substrate layers of the sensor according to a second embodiment of the invention.

[0027] The invention relates to an inductive position sensor 1, as illustrated in [Fig. 1] to [Fig. 5]. The inductive position sensor 1, associated with a visible coupling element 20 [Fig. 1], is intended to be mounted in a rotating electrical machine such as an electric motor of an electric or hybrid vehicle comprising a rotor rotating relative to a stator. The angular position of the rotor is determined relative to the stator.

[0028] The sensor comprises an electronic card 10 on which are arranged at least one transmitting antenna 11, at least one receiving element 12 and at least one signal processing unit 13.

[0029] According to one embodiment of the invention, at least one receiving antenna is arranged inside at least one transmitting antenna.

[0030] During operation of the sensor, at least one transmitting antenna 11 emits a magnetic field oscillating at a given frequency. A coupling element 20 is positioned so as to modify this magnetic field. According to one embodiment of the invention, the coupling element is mounted on one end of a rotor shaft to modify the magnetic field emitted by the transmitting antenna 11. The modified magnetic field generates an electromotive force in the receiving element 12. This electromotive force is processed by the signal processing unit 13 so as to provide output signals allowing the measurement of the position of the coupling element 20.

[0031] According to one embodiment of the invention, the coupling element 20 is a rotating element, for example with the rotor of the electric motor.

[0032] According to one embodiment of the invention, the coupling element has an external diameter identical to or greater than the external diameter of the transmitting antennas.

[0033] According to one embodiment of the invention, the electronic card 10 comprises openings 15 allowing connection to wires or to metal connection elements.

[0034] According to one embodiment of the invention, the number of windings of at least one receiving element 12 is proportional to the number of angular sectors of the casting element 20.

[0035] According to one embodiment of the invention, the electronic card 10 is made up of two substrate layers.

[0036] According to one embodiment of the invention, the connections between the transmission and reception elements and to at least one signal processing element are made with conductive elements 101, 102.

[0037] According to one embodiment of the invention, the conductive elements 101, 102 are located in a zone 30 different from that 40 where the transmission and reception elements 11 are located.

[0038] 12. According to one embodiment of the invention, the conductive elements 101, 102 are composed of a portion where the conductive elements 101, 102 are on the same substrate layer, and a portion 111, 112 where they are located on two different substrate layers of the electronic card 10, superimposed on each other.

[0039] In the context of the invention, the sensor 1 comprises a ground plane 17 positioned on the zone 30 of the conductive elements so as to extend to the zone 40 of the emission 11 and reception 12 elements.

[0040] For this, according to a first variant of the invention, the ground plane 17 is segmented 171, 172, 173, that is to say it is formed of several portions 171, 172, 173 arranged so as to surround the conductive elements 101, 102 without ever covering them.

[0041] In the context of the invention, the ground plane 17 is arranged on two substrate layers 13, 14.

[0042] The different portions 171, 172, 173 of the ground plane are arranged on the first 13 and the second 14 substrate layer and are connected to each other with metal vias 174 passing through the upper substrate 13 in its thickness to join the lower substrate 14. The upper substrate 13 and the lower substrate 14 are defined with respect to the fact that the two substrates are superimposed. There is therefore an upper substrate and a lower substrate, whatever the direction of orientation of the sensor 1.

[0043] According to an embodiment of the invention of this illustrated variant [Fig. 2], the portion 111, 112 comprises conductive elements 101, 102 located on two different substrate layers 13, 14 of the electronic card which are superimposed on each other.

[0044] Thus, on each substrate, there is at least one portion of ground plane 17 bypassing the conductive elements 101, 102. In this way, when the substrates are superimposed, thanks to all of the portions connected by the vias 174 [Fig. 5], a large part of the zone 30 where the conductive elements 101, 102 are located is covered by the ground plane 17.

[0045] According to a variant of the invention, the ground plane 17 is segmented as in the first variant and the conductive elements located on two different substrate layers 13, 14 of the electronic card of the portion 111, 112 are arranged so as not to overlap. The conductive elements of the portion 111, 112 are thus offset so that they are located on the at least two substrate layers 13, 14 but without being superimposed on each other as illustrated in [Fig. 5]. The offset of the conductive elements on each of the substrates makes it possible to extend the ground plane 17 over the two substrate layers 13, 14.

[0046] The ground plane 17 is thus made up of several portions 171, 172, 173 located on each of the two substrate layers 13, 14 of the electronic card 10. The portions 171, 172, 173 of the ground plane 17 are connected to each other by several metal vias 174 passing through the electronic card 10 in its thickness. That is to say that there is at least one portion on a substrate layer and a portion on another substrate layer.

[0047] Thus, with the sensor 1 according to the invention, when the coupling element superimposes the area of ​​the conductive elements, the conductive elements 101, 102 being included in the ground plane, without being covered, they no longer behave as disturbing elements.

[0048] The invention also relates to an electrical machine comprising a sensor 1 as described previously.

[0049] The scope of the present invention is not limited to the details given above and allows embodiments in many other specific forms without departing from the scope of the invention. Therefore, the present embodiments should be considered by way of illustration, and may be modified without departing from the scope defined by the claims.

Claims

CLAIMS 1. Inductive position sensor (1) for a rotating electrical machine comprising a printed circuit board (10), with two substrates (13, 14), on which are arranged at least one transmitting element (11) intended to transmit an oscillating magnetic field towards a rotating coupling element (20) to generate a modified magnetic field, and at least one receiving device (12) intended to detect the modified magnetic field, the connections between the at least one transmitting element and the at least one receiving element to at least one signal processing element are made with conductive elements (101, 102) located on a zone (30) different from that (40) where the transmitting (11) and receiving (12) elements are located, characterized in that it comprises a ground plane (17) positioned on the zone (30) of the conductive elements so as to extend to the zone (40) of the transmitting (11) and receiving (12) elements.

2. Inductive position sensor (1) according to claim 1, wherein the ground plane (17) is segmented (171, 172, 173) into several ground plane portions (171, 172, 173) arranged so as to surround the conductive elements (101, 102) without covering them.

3. Inductive position sensor (1) according to claim 1 or 2, wherein the ground plane (17) is arranged on two substrate layers (13, 14).

4. Inductive position sensor (1) according to one of claims 2 to 3 when it depends on 2, in which different portions (171, 172, 173) of the ground plane are arranged on the first (13) and the second (14) substrate layer and are connected to each other with metal vias (174) passing through the printed circuit board (10) (13) in its thickness to join another lower substrate (14).

5. Inductive position sensor (1) according to one of claims 1 to 4, wherein the conductive elements (101, 102), of a portion (111, 112) of conductive elements, located on two different substrate layers (13, 14) of the electronic card are superimposed relative to each other.

6. Inductive position sensor (1) according to one of claims 1 to 4, wherein the conductive elements (101, 102), of a portion (111, 112) of conductive elements, located on two different substrate layers (13, 14) of the electronic card are arranged so as not to overlap one another.

7. Electrical machine comprising a sensor (1) according to one of claims 1 to 6.

8. Electrical machine comprising a sensor (1) according to one of claims 1 to 6, in which the rotating electrical machine is an electric motor of an electric or hybrid vehicle comprising a rotor rotating relative to a stator.

9. Use of the sensor according to one of claims 1 to 6 for measuring the angular position of a rotor relative to a stator of an electrical machine.

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