Inductive angular position sensor arranged only on an angular sector

Abstract

Inductive position sensor comprising: -a primary coil (10) and -at least two secondary windings (201, 202, 203) of at least two secondary turns. The primary and secondary windings (10, 201, 202, 203) extend along an arc of a circle, each secondary winding (201, 202, 203) -extends over an angular sector of 360° / N -the surface of the turns wound in one direction corresponds to the surface of the turns wound in an opposite direction, -comprises two compensation turns connected in series with the turns of the corresponding secondary winding (201, 202, 203) such that: -each compensation turn is wound in the opposite direction to the winding of its neighboring secondary turn; - the two compensation turns of the same secondary winding (201, 202, 203) are wound in two opposite directions and angularly offset by an angle of 360° / N; and - the compensation turns wound in the same direction are superimposed. Abstract figure: Figure 11

Description

Title of the invention: Inductive angular position sensor arranged only on an angular sector

[0001] The present disclosure relates to an inductive angular position sensor arranged only on an angular sector. Technical field

[0002] The present disclosure relates to the field of inductive position sensors. Such a sensor makes it possible to determine a position of a mechanical part, or the like, without coming into contact with said mechanical part. This technology is used in many technical fields and is found in the automotive field. Prior art

[0003] The operating principle of an inductive sensor is based on the variation of coupling between a primary winding and at least two secondary windings, said windings forming a transformer operating at high frequency without using a magnetic circuit. The primary winding and the secondary windings are for example fixed and an electrically conductive part, generally called a "target", is in motion with the mechanical part considered to be mobile (or vice versa). The relative movement of the conductive target with the windings will vary the coupling between the primary winding and the secondary windings. Currents induced in the target modify the voltages induced in the secondary windings.Knowing the current flowing in the primary winding, it is then possible, knowing the geometry of the target and the windings, to determine the position of the target by analyzing the signals (the voltage) at the terminals of the secondary windings.

[0004] The present disclosure relates more particularly to inductive angular position sensors, i.e. a sensor for determining the angular position of a rotating shaft. The target is, for example, in the form of a tooth which rotates with the shaft. The inductive sensor is produced on a card arranged in a plane perpendicular to the axis of rotation of the shaft. The measurement of the angular position by the inductive sensor is then sensitive to the relative position of the sensor and the target. For a good measurement, the sensor and the target must be in two parallel planes and rotate around the same axis.

[0005] Besides the relative position of the sensor and the target, the structure of the sensor is also important. There are two main families of inductive angular position sensors: through-shaft sensors (the shaft whose angular position is measured passes through the plane of the sensor which surrounds the shaft) and sensors extending over an angular sector (they are arranged on the periphery of a tree, only partially surrounding it).

[0006] For a through-shaft sensor, the positioning errors between the shaft and the target are compensated for naturally and the measurement error is therefore relatively low.

[0007] The present disclosure relates more particularly to sensors extending over an angular sector. Such a sensor is for example described in document WO2022 / 248221. According to its abstract, this document relates to an inductive position sensor comprising, on the one hand, a primary coil and, on the other hand, at least one secondary coil which comprises at least two secondary windings each consisting of several turns produced on two layers of a printed circuit board. Each of said turns has a first generally concave part arranged on one layer of the printed circuit board and a second generally concave part arranged on another layer of the printed circuit board.Among the first parts and second parts of the turns of the two secondary windings, at least some of these first and second parts are arranged according to a mirror symmetry on either side of a transverse separation plane, this transverse separation plane being located between the two secondary windings and being orthogonal to the longitudinal direction.

[0008] With an inductive sensor of the angular sector type for example, it is necessary to ensure that it is correctly positioned relative to the shaft whose angular position is to be determined. It is assumed that the angular position measurement concerns a shaft rotating around an axis of rotation Oz and that the inductive sensor, ideally, is positioned in an Oxy plane while being centered on the Oy axis. It is assumed that the target which is linked to the shaft has a face opposite the sensor in the Oxy plane and rotates without eccentricity around the Oz axis.

[0009] There are four types of defects for the relative positioning of the target and the sensor: - the sensor can be offset (eccentric) on the Oy axis: this defect has little influence on the measurement; - the sensor may be offset (eccentric) on the Ox axis: this fault corresponds to an offset of the sensor which will be reflected in the absolute value measured and leads to a constant angular position error; - the sensor has a tilt around the Ox axis: this defect only causes a constant increase or decrease in the space between the sensor and its target. It does not significantly modify the measurement result; - the sensor has a tilt around the Oy axis: this defect has a significant effect on the measurement because the coupling between the windings at one end of the sensor is not the same as at the other end of the sensor. Summary

[0010] The present disclosure improves the situation. Its aim is to provide an inductive sensor for measuring angular position in the form of an angular sector having reduced sensitivity to a relative positioning defect between a target and the sensor, in particular with regard to a tilt defect causing the target to be closer to one end of the sensor than to its opposite end.

[0011] An inductive position sensor is proposed comprising: - a primary coil with at least one primary turn and - a secondary coil having at least two secondary windings each consisting of at least two secondary turns, in which: each primary turn surrounds all the turns of the secondary windings, the primary winding and the secondary winding extend along an arc of a circle, each secondary winding extends over an angular sector of 360° / N where N is an integer, the turns of each secondary winding are such that the surface area of ​​the turns wound in a first direction corresponds to the surface area of ​​the turns wound in a second direction opposite to the first.

[0012] According to the present disclosure, each secondary winding comprises two compensation windings each with at least one compensation turn, such that: - each compensation winding is connected in series with the turns of the corresponding secondary winding, is adjacent to secondary turns wound in the same direction and each turn of said compensation winding is wound in the opposite direction to the winding of said adjacent secondary turns; - for the same secondary winding, the turns of one compensation winding are wound in the opposite direction to the turns of the other compensation winding; - the two compensation windings of the same secondary winding are angularly offset by an angle of 360° / N; and - for all secondary windings, the compensation windings with turns wound in the same direction are superimposed, thus forming two superpositions of compensation windings.

[0013] The features set out in the following paragraphs may, optionally, be implemented, independently of one another or in combination with one another:

[0014] - the compensation turns are smaller in surface area than the secondary turns;

[0015] - the overall surface area of ​​the compensation turns of a secondary winding is between 15% and 1% of the total surface area of ​​the secondary turns of said winding secondary;

[0016] - the turns are made on at least two layers of a printed circuit board; in this variant, each secondary turn may have a first turn part produced on one layer of the printed circuit and a second turn part produced on another layer of the printed circuit, the first turn part and the second turn part being able to be connected to each other by a via.

[0017] According to another aspect, there is provided an electric motor comprising a rotor and a stator and having N pairs of electric poles, characterized in that it comprises, on the one hand, an inductive position sensor as defined above, arranged in a plane perpendicular to the axis of rotation of the stator, and, on the other hand, an electrically conductive part linked to the rotor and having N targets regularly distributed at the periphery of said conductive part and arranged so as to pass opposite the position sensor so as to vary the coupling between the primary coil and the secondary coil of the inductive sensor.

[0018] For such a motor, the primary winding of the inductive sensor can be sized such that it is permanently covered by a metal surface corresponding to the surface of two targets. This makes it possible to have a constant induction flux emitted by the primary coil.

[0019] According to another aspect, there is provided a vehicle provided with an electric motor as described above. Brief description of the drawings

[0020] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l

[0021] [Fig.l] schematically shows a positioning of an inductive sensor relative to an axis of rotation of an electric motor rotor. Fig. 2

[0022] [Fig.2] schematically shows an angular positioning defect of a sensor such as the sensor in [Fig.l] relative to a target. Fig. 3

[0023] [Fig.3] schematically shows a secondary winding and a corresponding target. Fig. 4

[0024] [Fig.4] shows a curve of variation of flux induced in the secondary winding of [Fig.3] when moving the target of [Fig.3]. Fig. 5

[0025] [Fig.5] schematically shows the secondary winding of [Fig.3] with turns compensation according to this disclosure. Fig. 6

[0026] [Fig.6] shows an embodiment for the superposition of the compensation turns of [Fig.5] with the secondary winding of [Fig.3]. Fig. 7

[0027] [Fig.7] shows a detail of an alternative embodiment for the winding of [Fig.6]. Fig. 8

[0028] [Fig.8] shows in top view a primary winding and a first secondary winding according to the present disclosure. Fig. 9

[0029] [Fig.9] shows in top view the primary winding of [Fig.8] and a second secondary winding according to the present disclosure. Fig. 10

[0030] [Fig. 10] shows in top view the primary winding of [Fig.8] and a third secondary winding according to the present disclosure. Fig. 11

[0031] [Fig. 11] shows the primary winding of [Fig.8] and the three secondary windings of Figures 8 to 10 superimposed to form a sensor according to the present disclosure. Fig. 12

[0032] [Fig. 12] shows the windings of [Fig. 11] in perspective. Fig. 13

[0033] [Fig. 13] shows the sensor of Figures 11 and 12 in cooperation with two targets. Description of the embodiments

[0034] Reference is now made to [Fig. 1]. This figure illustrates a sectoral inductive sensor 2 of the prior art such as for example a sensor described in document WO2022 / 248221 to which reference is made here (in particular page 6, line 25 to page 12, line 4), as well as in documents FR3002034 and FR3068464 cited in this document WO'221. This inductive sensor 2 is intended here to determine the angular position of an electric motor which comprises N pairs of electric poles. It is formed of a primary winding and at least two secondary windings. To know the angular position of the motor, the inductive sensor 2 cooperates with an electrically conductive target which is linked to the rotor and rotates with it, modifying the coupling between the primary winding and the secondary windings.The primary winding is supplied with a known high-frequency current and by analyzing the signals (voltages) induced in the secondary windings when the target passes, it is possible to know the angular position of the motor. It is advisable that a target permanently covers a secondary winding which extends over an angular sector of 360° / N.

[0035] A sector sensor configuration as illustrated in [Fig.l] allows a gain of space compared to a crown-shaped sensor which would be arranged at the end of the shaft / rotor or at the periphery of this shaft / rotor. On the other hand, a sector sensor is more sensitive to a misalignment with the target. It can be assumed that the target is “perfectly” mounted on the motor rotor shaft, that is to say that the target has a rotational movement around the axis of the motor (without eccentricity or angular misalignment) and has a face opposite the sensor perpendicular to its axis of rotation because fairly precise machining can be carried out. It is assumed in the remainder of the description that the inductive sensor has a positioning defect relative to the target but the person skilled in the art will understand that this is in fact a relative positioning defect.

[0036] It is assumed here that the ideal position of the sectorial inductive sensor 2 is a position in a plane Oxy, the rotor rotating around an axis Oz and the sensor being centered on the axis Oy.

[0037] Four positioning defects may appear. The inductive sensor 2 may be offset along the Oy axis. If the offset is not too large, the target will normally cover the inductive sensor 2 and the couplings between the primary winding and the secondary windings will not be affected.

[0038] If the inductive sensor is shifted by translation along the OX axis, the determined angular position will always have the same angular shift, the value of which will depend on the shift and the radius on which the sensor is located.

[0039] If the inductive sensor is inclined by a rotation around the axis Ox, then the space (commonly called "gap" or "airgap") between the target and the inductive sensor 2 will be modified. This will have an influence on the intensity of the signal recorded at the output of the secondary winding but not (or very little) on the shape of the signal so that it is still possible to determine the angular position of the rotor.

[0040] On the other hand, if the inductive sensor is tilted by rotation around the OY axis, then the target will be closer, when it passes in front of the sensor, to one part of a secondary winding than to an opposite part. The shape of the signal is affected.

[0041] [Fig.2] illustrates in the Oxz plane the relative position of a target 4 with the inductive sensor 2. It can be seen that the inductive sensor 2 makes a “gamma” angle with the Oxy plane so that the target 4 which moves along the Ox axis (i.e. from left to right or vice versa in [Fig.2]) moves away from (or approaches) the inductive sensor 2 during its passage in front of the sensor.

[0042] [Fig. 3] then illustrates a secondary winding 20 comprising a first turn 22 and a second turn 24. It is assumed that in top view (i.e. perpendicular to the plane of the inductive sensor 2 which is produced on a printed circuit board) the surface of the first turn 22 equals the surface of the second turn 24. However, the first turn 22 is wound in the direction opposite to the winding direction of the second turn 24. A current flowing in a primary winding 10 (Figures 8 to 12) will produce opposite magnetic fluxes (or electromotive forces) in the first turn 22 and in the second turn 24, which is illustrated by the symbols + and - (arbitrary) in [Fig. 3]. In this figure, the turns are symmetrical. It can be seen in [Fig. 3] that when the target 4 passes in front of the inductive sensor 2, the target is closer to the first turn 22 (distance a) than to the second turn 24 (distance b with b>a). Therefore, while the turns are sized so that the overall flux through the two turns (first turn 22 and second turn 24) is zero when there is no target. When there is a target 4, the total flux in the secondary winding 20 (turn 22 or 24) depends on the position of the target relative to the winding (turn).Over a mechanical period (360° / N) of rotation of the target 4, the total flux seen by the secondary winding 20 is sinusoidal in shape depending on the angular position of the target. However, due to the illustrated inclination, we have here a flux whose shape is no longer sinusoidal as illustrated in [Fig.4] on which illustrated surfaces A and B representative of the magnetic flux through a turn are different.

[0043] The solution proposed by the present disclosure is to add a first compensation winding and a second compensation winding, each with at least one turn. For the description of the principle of the present disclosure, it is assumed that the secondary winding considered has only two turns (first turn 22 and second turn 24) and that the first compensation winding has a single first compensation turn 220 and the second compensation winding has a single second compensation turn 240 in series with the first turn 22 and the second turn 24. [Fig. 5] illustrates the secondary winding of [Fig. 3] and the two compensation turns / windings. It should be noted that adding additional turns / windings to a set of secondary turns produces an addition of additional flux to the flux seen by the set of secondary turns.

[0044] The first compensation turn 220 and the second compensation turn 240 must produce a zero flux when the inductive sensor is indeed parallel to the target (angle “gamma” equal to 0°), whatever the position of the target 4. The first compensation turn 220 is therefore offset by 360° / N relative to the second compensation turn 240 and these two compensation turns have the same surface area but are wound in opposite directions so that if an induced flux is positive in one of the two compensation turns then the induced flux in the other compensation turn will be negative. The two compensation turns for the secondary winding 20 are thus of opposite signs and of identical size. They are preferably symmetrical relative to a median angular position.

[0045] [Fig.6] illustrates a diagram allowing the first compensation turn 220 and the second compensation turn 240 to be integrated into the secondary winding 20 so as to be in series with the first turn 22 and the second turn 24. To carry out this series assembly on a printed circuit, it is necessary to provide at least two layers on the printed circuit and vias connecting said layers. [Fig.7] shows an alternative embodiment for a first compensation turn 2200.

[0046] To produce an inductive sensor, it is necessary to provide a primary winding 10 and at least two secondary windings. The embodiment adopted here provides an embodiment of a sensor with three secondary windings. When two secondary windings are used, the signal at the terminals of one winding corresponds to the sine function of the angular position of the motor and that at the terminals of the other winding to the cosine function and the two signals then make it possible to know the position of the motor over 360° (electrical or 360° / N mechanical). With three secondary windings, a first secondary winding 201 corresponds for example to the sine(x) function, while the second secondary winding 202 is offset relative to the first secondary winding to correspond to the sine(x+120°) function and the third secondary winding 203 then corresponds to the sine(x+240°) function.The rules of trigonometry also make it possible to find the angular position x of the motor from the three signals induced in the secondary windings.

[0047] [Fig.8] illustrates an example of a first secondary winding 201 for producing a sensor according to the present disclosure. It is noted that the turns of this first secondary winding 201 are formed on at least two layers of the printed circuit. This first secondary winding 201 comprises a first compensation turn 221 and a second compensation turn 241, these two compensation turns being arranged symmetrically with respect to the axis Oy (when the sensor does not have an offset with respect to its nominal position).

[0048] Similarly, Figures 9 and 10 respectively illustrate a second secondary winding 202 and a third secondary winding 203. The second secondary winding 202 comprises a first compensation turn 222 and a second compensation turn 242 while the third secondary winding 203 comprises a first compensation turn 223 and a second compensation turn 243.

[0049] Each time, the compensation turns have the same surface area. Two compensation turns of the same secondary winding are offset from each other by 360° / N and are wound in opposite directions. It is noted that in these examples of Figures 8 to 10, each of the secondary windings has several secondary turns wound in a first direction and the same number of secondary turns wound in the opposite direction. On the other hand, each compensation winding has only one turn. However, it may be envisaged to have a secondary winding with two turns (one in each direction) and / or compensation windings with several turns (all in the same direction) each.

[0050] Figures 11 and 12 illustrate a sensor obtained by joining the primary winding 10 (here comprising four turns with a printed circuit used for example having four layers to optimize the induction flux). It is noted that the turns of the secondary windings are offset from one winding to the other (by 120° / N) but the first compensation turns 221, 222, and 223 are superimposed as well as the second compensation turns 241, 242, and 243.

[0051] It is noted that the compensation turns relative to the turns of the secondary windings are of reduced size, for example their overall surface area is of the order of a few percent of the overall surface area of ​​the other turns, preferably less than 15%. Here, the term overall surface area is understood to mean the sum of the surfaces of all the turns considering a secondary winding. The surface area of ​​a turn corresponds in top view to the surface area delimited by the turn considered. We then consider the surface area of ​​each of the secondary turns, on the one hand, and the surface area of ​​each of the compensation turns, on the other hand. The size of each of the compensation turns is calculated during the design of the sensor according to the geometry of the motor, the turns, the targets and the machining and assembly tolerances.Generally these tolerances are limited and therefore the size of the compensation turns also remains limited, for example of the order of 1% of the sizes of the turns of the windings. In other words, in a secondary winding, the induced flux passing through the compensation turns can be of the order of 10%, most often less than 5% and preferably of the order of 0.5 to 2% of the flux passing through the other turns of the secondary winding considered. Taking the example of [Fig.5], if the secondary winding 20 comprises a turn 22 with a surface area of ​​100 units and a turn 24 with a surface area of ​​100 units also (so that the overall flux is zero), then the surface area of ​​the compensation turn 220 will be less than 15 units, of the order of 10 units but rather less than 5 units, or even 2 units. The surface area of ​​the compensation coil 240 will be the same as that of the compensation coil 220.As another illustrative and non-limiting numerical example, if the secondary winding comprised two secondary turns each with a surface area of ​​100 units wound in one direction and two secondary turns each with a surface area of ​​100 units wound in the other direction, we would have a total secondary winding surface area of ​​400 units. If the compensation windings were to represent 5% of the total surface area of ​​the secondary winding considered, i.e. a surface area of ​​20 units, according to the calculations carried out, then we could for example have a compensation winding with a turn with a surface area of ​​10 units wound in one direction and another compensation winding with a turn with a surface area of ​​10 units wound in the other direction. We could also have two compensation windings each with two compensation turns with a surface area of ​​5 units.

[0052] Finally, [Fig. 13] illustrates the inductive sensor of figures 11 and 12 in situ and cooperating with targets linked to a conductive part mounted on a motor rotor. electric.

[0053] In this [Fig.13], two neighboring targets 4 cover the first compensation turns (or windings) for one and the second compensation turns (or windings) for the other. The angular offset between two targets 4 also being 360° / N, this figure illustrates the offset of 360° / N between the two stacks of compensation turns / windings.

[0054] The size (surface) of the primary winding 10 may be such that it extends over an angular sector of 360° / N increased by the size of a target, the geometry of the primary turns (with radial edges) and of the targets 4 (also with radial edges) being adapted so that the primary winding 10 is always covered by two targets 4, thus making it possible to have a constant primary flux. Industrial application

[0055] The present technical solutions can be applied in particular to reduce the effects of mechanical defects on the performance of an inductive angular position sensor. Sector-type sensors (extending only over a part of the periphery of a shaft) are more particularly targeted here because the performance problems are less significant on a sensor arranged at the end of a shaft or on a through-sensor because a “natural” (or physical) compensation is then established.

[0056] The solution proposed here has the advantage of compensating for alignment defects, particularly inclination between a target and an inductive sensor. The compensation is carried out in the sensor itself without generating any additional cost for it.

[0057] The proposed solution can be adapted to a large number of situations. It works regardless of the number of poles of the electric motor. It can be adapted to any type of inductive sensor, with two or three (or more) secondary windings and with any secondary winding turn structures. The preferred embodiments use turns on several layers as described in the aforementioned documents FR3002034 and / or FR3068464 and or WO2022 / 248221 but also with elementary winding structures as illustrated schematically in [Fig.3].

[0058] The present disclosure is not limited to the embodiment described and to the variants mentioned above, only as examples, but it encompasses all the variants that a person skilled in the art may envisage within the framework of the protection sought.

Claims

Claims

1. Inductive position sensor comprising: - a primary coil (10) with at least one primary turn and - a secondary coil having at least two secondary windings (20; 201, 202, 203) each consisting of at least two secondary turns (22, 24), in which: each primary turn surrounds all the turns of the secondary windings (20; 201, 202, 203), the primary winding (10) and the secondary winding (20; 201, 202, 203) extend along an arc of a circle, each secondary winding (20; 201, 202, 203) extends over an angular sector of 360° / N where N is an integer, the turns of each secondary winding are such that the surface area of ​​the turns wound in a first direction corresponds to the surface area of ​​the turns wound in a second direction opposite to the first, characterized in that each secondary winding (20; 201, 202, 203) comprises two compensation windings (220, 240; 221, 222, 223, 241, 242, 243) each with at least one compensation turn, such that: - each compensation winding (220, 240; 221, 222, 223, 241, 242, 243) is connected in series with the turns of the secondary winding (20; 201, 202, 203) corresponding, is adjacent to secondary turns wound in the same direction and each turn of said compensation winding is wound in the opposite direction to the winding of said adjacent secondary turns; - for the same secondary winding (20; 201, 202, 203), the turns of a compensation winding (220, 240; 221, 222, 223, 241, 242, 243) are wound in the opposite direction to the turns of the other compensation winding; - the two compensation windings (220, 240; 221, 222, 223, 241, 242, 243) of the same secondary winding (20; 201, 202, 203) are angularly offset by an angle of 360° / N; and - for all the secondary windings, the compensation windings (221, 222, 223, 241, 242, 243) with turns wound in the same direction are superimposed, thus forming two superpositions of compensation windings.

2. Inductive position sensor according to claim 1, characterized in that the compensation turns (220, 240; 221, 222, 223, 241, 242, 243) are smaller in surface area than the secondary turns.

3. Inductive position sensor according to one of claims 1 or 2, characterized in that the overall surface area of ​​the compensation turns (220, 240; 221, 222, 223, 241, 242, 243) of a secondary winding is between 15% and 1% of the overall surface area of ​​the secondary turns of said secondary winding (20; 201, 202, 203).

4. Inductive position sensor according to one of claims 1 to 3, characterized in that the turns are produced on at least two layers of a printed circuit board.

5. Inductive position sensor according to claim 4, characterized in that each secondary turn has a first turn part produced on one layer of the printed circuit and a second turn part produced on another layer of the printed circuit, the first turn part and the second turn part being connected to each other by a V1 Q

6. V Id. Electric motor comprising a rotor and a stator and having N pairs of electric poles, characterized in that it comprises, on the one hand, an inductive position sensor according to one of claims 1 to 5 arranged in a plane perpendicular to the axis of rotation of the stator, and, on the other hand, an electrically conductive part linked to the rotor and having N targets (4) regularly distributed at the periphery of said conductive part and arranged so as to pass opposite the position sensor so as to vary the coupling between the primary coil (10) and the secondary coil (20; 201, 202, 203) of the inductive sensor.

7. Electric motor according to claim 6, characterized in that the primary winding (10) of the inductive sensor is dimensioned such that it is permanently covered by a metal surface corresponding to the surface of two targets (4).

8. Motor vehicle, characterized in that it comprises an electric motor according to one of claims 6 or 7.

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