EP4374140A1

EP4374140A1 - High-layer excitation coil for inductive position sensor

Info

Publication number: EP4374140A1
Application number: EP21783052.0A
Authority: EP
Inventors: Andreas Kurz; Débora PEREIRA; Jorge CABRAL; José António AZEVEDO GONÇALVES; Robert ALEXANDER DAUTH; Sina FELLA; Tim KRZYZANOWSKI; Ville SAMULI KIVIJARVI
Original assignee: Universidade do Minho; Bosch Car Multimedia Portugal SA
Current assignee: Universidade do Minho; Bosch Car Multimedia Portugal SA
Priority date: 2021-09-10
Filing date: 2021-09-14
Publication date: 2024-05-29
Also published as: WO2023037153A1

Abstract

The present application describes a high-layer excitation coil (101) for inductive position sensors (100). The inductive position sensor (100) is arranged in a multi-layer printed circuit board with independently stacked layers which comprises an excitation coil (101) and at least two receiver coils (102, 103), interlaced in the multi-layered printed circuit board arrangement. The excitation coil (101) circularly surrounds the limits defined by the at least two receiver coils (102,103) and comprises a set of traces, overlapped and arranged in the independently stacked layers, being connected to each other through a set of vias.

Description

DESCRIPTION

"High-layer excitation coil for inductive position sensor"

Technical Field

The present application describes a high-layer excitation coil for inductive position sensors.

Background art

Inductive position sensors are usually used to measure the positioning of a moving target. From known technical art, there are several approaches with regard to the operating principles of inductive sensors. The sensor herein disclosed uses the principle of coupled coils.

Inductive position sensors based on coupled coils typically are constituted by one excitation (transceiver / Tx) coil and at least one receiver (Rx) coil, typically two or three receiver coils. These coils are usually integrated, and form a PCB Sensor, which also comprises an application-specific integrated circuit (ASIC). This ASIC is needed for the excitation of the transceiver coil, and the demodulation / amplification of the induced voltage signals on the receiver coils. Once the amplitude of the induced voltage signals depends on the target position, these signals are used for the calculation of the position value.

Due to the ASIC specifications, there are several requirements, or limitations, which have a direct impact on the coil system. One important specification is the impedance of the transceiver coil, because the internal oscillator circuit of the ASIC can be represented as an AC voltage source. A low impedance value can lead to a high current, which might result in an overload of the ASIC. For the sensor application, a specification of the inductance and quality-factor instead of the impedance of the transceiver coil is more useful, because the sensor principle is based on the inductive coupling. The inductance and Q- factor value depend mainly on the geometry of the coil. Most commonly there are transceiver coils used with more than one winding and placed on more than one layer.

The transceiver and receiver coils are placed on the same PCB and must be directly connected to the ASIC. Typically, the transceiver and receiver coils are placed on different PCB layers due to the connection to the ASIC.

For the design of the excitation coil, and to ensure a high Q-factor, two parameters are of major importance, the coil diameter and the number of windings. Often, the diameters are given by the systems final application, and are therefore fixed. However, one can add more windings on each utilized PCB layer or add them to new layers.

If the coil layout is very small, there can be space for a single excitation-coil winding per layer only. Therefore, frequently it is necessary to use all available PCB layers in order to achieve the predetermined specifications. However, frequent conflict with the routing of the receiver coils out of the excitation-coil area occurs.

The use of a special routing layout as herein proposed in present application will allow to overcome this known limitation. Summary

Present invention describes an inductive position sensor, arranged in a multi-layer printed circuit board with independently stacked layers, comprising an excitation coil; at least two receiver coils, interlaced in the multi-layered printed circuit board arrangement; the excitation coil, circularly surrounding the limits defined by the at least two receiver coils, comprising a set of winding traces, overlapped and arranged in the independently stacked layers, said winding traces being connected to each other through a set of vias.

In a proposed embodiment, the independently stacked layers comprise at least four layers: Layer A, Layer B, Layer C, and Layer D.

In another proposed embodiment, the set of winding traces comprises a ring-shaped trace arranged on Layer A; a ring- shaped trace arranged on Layer B; a ring-shaped trace arranged on Layer C; and a ring-shaped trace arranged on Layer D.

In another possible embodiment, the ring-shaped trace arranged on Layer A comprises a Tx connection.

In another possible embodiment, the ring-shaped trace arranged on Layer C comprises a Tx connection.

In another possible embodiment, the both Tx connections are connected to an application-specific integrated circuit. In another possible embodiment, the application-specific integrated circuit is adapted to perform signal processing, excitation, demodulation and amplification of induced voltage signals on the at least two receiver coils.

In another possible embodiment, the set of vias comprise a via adapted to connect Layer A trace to Layer B trace.

In another possible embodiment, the set of vias comprise a via adapted to connect Layer C trace to Layer D trace.

In another possible embodiment, the set of vias comprise a via adapted to connect Layer B trace to Layer C trace.

General Description

This special transceiver coil design allows to solve the problem of crossing tracks with the same inductance/Q- factor, reducing the number of windings per layer of the multilayer printed circuit board (PCB).

Therefore, and with the disclosed layout, the needed area per layer for the transceiver coil is minimized resorting to the use of additional windings on overlapped layers and a smart connection to the ASIC. With less area per layer for the transceiver coil, the same inductance and Q-factor value can be achieved. Furthermore, the spanned area of the receiver coils can be increased, which leads to a higher signal amplitude gain and signal-to-noise ratio. With this technique, it is possible to achieve an improvement with regard to presently know architectures, making use of all PCB layers for the excitation coil instead of just a few layers only, while simultaneously routing the connections from the receiver coils to the outside. This can be achieved by adding an additional cut-out to the multilayer printed circuit board (PCB), meaning the overall diameter is not increased. This fulfils and ensure typical space requirements.

In the standard layouts, the routing of the receiver (Rx) coils is performed in different layers than the ones used for the transceiver (excitation / Tx) coil.

Present disclosure suggests a layout where the transceiver (excitation / Tx) coil is placed over all layers of the PCB, overlapping the circular layered traces, and connecting them through vias, allowing the maximization of the Q-factor. The routing of the receiver (Rx) coils is done by using a small segment of the PCB where the coil diameter is not limited to the excitation-coil area. A gap cut-out in the excitation coil is performed, and removed the remaining part, placing it with a slightly increased diameter on another layer.

A favourable solution is to place the largest deviations of the excitation coil from a circle in the layer (s) far away from the target, as any asymmetry can lead to an asymmetric distribution of induced Eddy currents, and thus an enhanced nonlinear signal output.

Such excitation coil can be used for linear and rotor positioning sensors. Brief description of the drawings

For better understanding of the present application, figures representing preferred embodiments are herein attached which, however, are not intended to limit the technique disclosed herein.

Fig. 1 - represents in a 3D perspective the model layout of the proposed inductive position sensor with the High-layer excitation coil. Reference numbers represent:

100 - inductive position sensor;

101 - High-layer excitation coil / Tx coil;

102 - Receiver coil A / Rx coil A;

103 - Receiver coil B / Rx coil B;

1011 - via connection between Layer F traces and Layer

E traces of the excitation coil;

1012 - via connection between Layer A traces and Layer

B traces of the excitation coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1015 - via connection between Layer E traces and Layer

F traces of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1017 - Excitation / Tx connection of the excitation coil;

1018 - Excitation / Tx connection of the excitation coil. Fig. 2 - represents an overall 3D model of the High-layer excitation coil. In this proposed layout perspective, it is possible to verify the existence of multiple layers, in the exemplified and not limiting case six layers, of stacked and overlapped circular traces connected through all the layers by connection points identified by vias. Reference numbers represent:

101 - High-layer excitation coil / Tx coil;

1011 - via connection between Layer F traces and Layer

E traces of the excitation coil;

1012 - via connection between Layer A traces and Layer

B traces of the excitation coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1015 - via connection between Layer E traces and Layer

F traces of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1017 - Excitation / Tx connection of the excitation coil;

1018 - Excitation / Tx connection of the excitation coil.

Fig. 3 - represents a detailed view of the 3D model of the High-layer excitation coil. This layout shows a more detailed embodiment of the overlapped circular traces connected through all the layers by its connection points. Reference numbers represent:

101 - High-layer excitation coil / Tx coil; 1011 - via connection between Layer F traces and Layer

E traces of the excitation coil;

1012 - via connection between Layer A traces and Layer

B traces of the excitation coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1015 - via connection between Layer E traces and Layer

F traces of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1017 - Excitation / Tx connection of the excitation coil;

1018 - Excitation / Tx connection of the excitation coil.

Fig. 4 - represents a Top View of the High-layer excitation coil with multilayer overlapping. Reference numbers represent:

101 - High-layer excitation coil / Tx coil;

1011 - via connection between Layer F traces and Layer

E traces of the excitation coil;

1012 - via connection between Layer A traces and Layer

B traces of the excitation coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil; 1015 - via connection between Layer E traces and Layer

F traces of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil.

Fig. 5 - represents a detailed view of the 3D model of the High-layer excitation coil. This layout shows a more detailed embodiment of the overlapped circular traces connected through Layer A and Layer B by its connection points. Reference numbers represent:

101 - High-layer excitation coil / Tx coil;

1012 - via connection between Layer A traces and Layer

B traces of the excitation coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1017 - Excitation / Tx connection of the excitation coil;

1021 - Layer A circular trace of the excitation coil;

1022 - Layer B circular trace of the excitation coil;

Fig. 6 - represents a detailed view of the 3D model of the High-layer excitation coil. This layout shows a more detailed embodiment of the overlapped circular traces connected through Layer B and Layer C by its connection points.

Reference numbers represent:

101 - High-layer excitation coil / Tx coil; 1012 - via connection between Layer A traces and Layer

B traces of the excitation coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1022 - Layer B circular trace of the excitation coil;

1023 - Layer C circular trace of the excitation coil.

Fig. 7 - represents a detailed view of the 3D model of the High-layer excitation coil. This layout shows a more detailed embodiment of the overlapped circular traces connected through Layer C and Layer D by its connection points. Reference numbers represent:

101 - High-layer excitation coil / Tx coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1023 - Layer C circular trace of the excitation coil;

1024 - Layer D circular trace of the excitation coil. Fig. 8 - represents a detailed view of the 3D model of the High-layer excitation coil. This layout shows an additional and more detailed embodiment of the overlapped circular traces connected through Layer D and Layer E by its connection points. Reference numbers represent:

101 - High-layer excitation coil / Tx coil;

1011 - via connection between Layer F traces and Layer E traces of the excitation coil;

1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1015 - via connection between Layer E traces and Layer

F traces of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1018 - Excitation / Tx connection of the excitation coil;

1024 - Layer D circular trace of the excitation coil;

1025 - Layer E circular trace of the excitation coil.

Fig. 9 - represents a detailed view of the 3D model of the High-layer excitation coil. This layout shows an additional and more detailed embodiment of the overlapped circular traces connected through Layer E and Layer F by its connection points. Reference numbers represent:

101 - High-layer excitation coil / Tx coil;

1011 - via connection between Layer F traces and Layer E traces of the excitation coil; 1013 - via connection between Layer C traces and Layer

D traces, and blind via on Layer B and Layer E of the excitation coil;

1014 - via connection between Layer D traces and Layer

E traces, and blind via on Layer B of the excitation coil;

1015 - via connection between Layer E traces and Layer

F traces of the excitation coil;

1016 - via connection between Layer B traces and Layer

C traces, and blind via on Layer F of the excitation coil;

1018 - Excitation / Tx connection of the excitation coil;

1025 - Layer E circular trace of the excitation coil;

1026 - Layer F circular trace of the excitation coil.

Description of Embodiments

With reference to the figures, some embodiments are now described in more detail, which are however not intended to limit the scope of the present application.

As previously disclosed, present application describes a special transceiver / High-layer excitation coil (101) that allows to overcome known problems related with the trace crossing in printed circuit boards.

In order to achieve the proposed goals previously mentioned, the excitation coil (101), in a possible and not limiting embodiment, will be implemented over a multilayer printed circuit board with a minimum of four layers.

Based on figure 1, an inductive position sensor (100) is disclosed, comprising a High-layer excitation coil (101) and two interlaced receiver (Rx) coils, Receiver coil A (102) and Receiver coil B (103). Said receiver coils (102, 103) are arranged in an interlaced multi-layered arrangement. The excitation coil (101) of the inductive position sensor (100) is vertically stacked over a set of multiple layers of the PCB on a specifically designed layout which allows to achieve a better performance. The excitation coil (101) comprises two independent connections (107, 108) to an external component and which are made available one of the possible embodiments on Layer A and Layer E of the PCB. The connection between the layers of the PCB, and respective circular traces that form the excitation coil (101), is ensured through connection points or vias strategically placed and arranged in order to allow the stacking of said circular traces that make part of the coil (101).

Figure 2 illustrates the overall 3D arrangement of the stacked layers on the multi-layered PCB. The proposed and not limiting arrangement of the excitation coil (101) disclosed in Fig. 2 comprises at least six circular winding traces (1021, 1022, 1023, 1024, 1025 ,1026), each one arranged on a separated layer of the PCB, vertically stacked in a ring-shaped arrangement. In the proposed six-layer arrangement, the ring-shaped trace (1021) is arranged on Layer A; the ring-shaped trace (1022) is arranged on Layer B; the ring-shaped trace (1023) is arranged on Layer C; the ring-shaped trace (1024) is arranged on Layer D; the ring- shaped trace (1025) is arranged on Layer E and the ring- shaped trace (1026) arranged on Layer F. The connections between the layers are ensured by vertical vias (1011, 1012, 1013, 1014, 1015). In figure 3 is possible to identify the proposed arrangement of the traces and the vias that allow to achieve present invention. Thus, and as illustrated in the figure 5, it is disclosed the layout arrangement on Layer A and Layer B of the PCB. The trace layout on Layer A (1021) will perform a nearly perfect 360-degree circle surrounding the receiver coils (102, 103). The trace layout on Layer A (1021) comprises a Tx connection (1018) which points directly outside the circular coil. Layer A circular trace (1021) will be connected to the beneath layer, Layer B, by the via connection (1012) that routes the induced signal to the layer bellow. Layer B circular trace (1022), will perform a nearly 360-degree circular path along the previously traced path arranged in (1021), but before the meeting point of the via (1012), the trace (1022) will be pushed outside of the previous routing in direction to via (1016). This via (1016) will ensure the connection between Layer B traces (1022) and Layer C traces (1023), and blind via on Layer F. The circular Layer B traces (1022) will describe a complete circular loop over itself with more than 360-degrees.

As illustrated in the figure 6, it is disclosed the layout arrangement on Layer B and Layer C of the PCB. The circular trace layout on Layer B (1022), will be connected to the beneath routed layer, Layer C, through the via connection (1016) that routes the induced signal to the layer bellow. Layer C comprises a circular trace (1023) that performs a nearly perfect 360-degree circular path along the previously traced path arranged in Layer B circular trace (1022), but before meeting again with same starting point of via (1016), the trace (1023) will be pushed inside of the previous routing trace in direction to via (1013). This via connection between Layer C traces and Layer D traces (1013), installed in the internal side of the circular arrangement of multi- layered traces and aligned with via connection between Layer B traces and Layer C traces (1016), will ensure the connection between Layer C traces (1023) and Layer D traces (1024), and blind via on Layer B and on Layer E. The circular Layer C traces (1023) will describe a complete circular loop over itself of 360-degrees.

In figure 7, it is disclosed the layout arrangement on Layer C and Layer D of the PCB. The circular trace layout on Layer C (1023), will be connected to the beneath routed layer, Layer D, through the via connection (1013) that routes the induced signal to the layer bellow. Layer D comprises a circular trace (1024) that performs a nearly perfect 360- degree circular path along the previously traced path arranged in Layer C circular trace (1023), but before meeting again with same starting point of via (1013), the trace (1024) will be pushed inside of the previous routing trace in direction to via (1014) that is placed on the near side of via (1013). The circular Layer D traces (1024) will describe a complete circular loop over itself of 360-degrees. Still with regard to via (1013), and in addition to ensuring the connection between Layer C trace (1023) to Layer D trace (1024), said via (1013) also provides a blind connection to Layer B and Layer E.

In figure 8, it is disclosed the layout arrangement on Layer D and Layer E of the PCB. The circular trace layout on Layer D (1024), will be connected to the beneath routed layer, Layer E, through the via connection (1014) that routes the induced signal to the layer bellow. Layer E comprises a circular trace (1025) that performs a nearly perfect 360- degree circular path along the previously traced path arranged in Layer D circular trace (1024), but before meeting again with same starting point of via (1014), the trace (1025) will be pushed outside of the previous routing trace in direction to via (1015) that is placed on the near side of via (1016), outside of the circular path of the excitation coil. The circular Layer E traces (1025) will describe a complete circular loop over itself of 360-degrees.

The ring-shaped trace (1025) arranged on Layer E also comprises another trace segment of approximately a quarter of a circular lap of the excitation coil, placed along the side of via (1015), that ensures the accessibility to the Tx connection (1018), and that, by said trace (1025) will also ensure the connection to via (1011) that is adapted to connect Layer F traces (1026) to Layer E traces (1025).

Still with regard to via (1014), and in addition to ensuring the connection between Layer D trace (1023) to Layer E trace (1025), said via (1014) also provides a blind connection to

Layer B and Layer B.

Finally, in figure 9, it is disclosed the layout arrangement on Layer E and Layer F of the PCB. The circular trace layout on Layer E (1025), will be connected to the beneath routed layer, Layer F, through the via connection (1015) that routes the induced signal to the layer bellow. Layer F comprises a circular trace (1026) that performs a nearly perfect 360- degree circular path along the previously traced path arranged in Layer E circular trace (1025), but before meeting again with same starting point of via (1015), in a possible embodiment, approximately a quarter of a circular excitation coil turn, the trace (1026) will be pushed outside of the previous routing trace in direction to via (1011) that is placed outside of the circular path of the excitation coil. The circular Layer F traces (1026), in one possible embodiment, will describe a tree-quarter of circular loop over itself. The circular Layer F trace (1026) connection to via (1011), will ensures the connection between routed traces on mentioned layers 6 and 5 (1026, 1025), especially to the above-mentioned trace segment (1025) that is connected to the Tx connection (1018).

The two connection points (1017, 1018) are responsible to allow the connection of the multi-layered excitation coil to an application-specific integrated circuit. In the proposed designed excitation coil, the induced current flow will enter through the Tx connection (1017), traveling along the traces (1021, 1022, 1023, 1024, 1025, 10266) arranged on the six layers of the PCB in an counter-clockwise rotation, exiting the coil through Tx connection (1017). The application- specific integrated circuit will be adapted to perform signal processing, excitation, demodulation and amplification of the induced voltage signals on the at least two receiver coils.

Claims

1. Inductive position sensor (100), arranged in a multi- layer printed circuit board with independently stacked layers, comprising an excitation coil (101); at least two receiver coils (102, 103), interlaced in the multi-layered printed circuit board arrangement; the excitation coil (101), circularly surrounding the limits defined by the at least two receiver coils (102, 103), comprising a set of winding traces, overlapped and arranged in the independently stacked layers, said winding traces being connected to each other through a set of vias.

2. Inductive positioning sensor (100) according to previous claim, wherein the independently stacked layers comprise at least four layers: Layer A, Layer B, Layer C and Layer D.

3. Inductive positioning sensor (100) according to any of the previous claims, wherein the set of winding traces comprises a ring-shaped trace (1021) arranged on Layer A; a ring-shaped trace (1022) arranged on Layer B; a ring-shaped trace (1023) arranged on Layer C; and a ring-shaped trace (1024) arranged on Layer D.

4. Inductive positioning sensor (100) according to any of the previous claims, wherein the ring-shaped trace (1021) arranged on Layer A comprises a Tx connection (1017).

5. Inductive positioning sensor (100) according to any of the previous claims, wherein the ring-shaped trace (1023) arranged on Layer C comprises a Tx connection (1018).

6. Inductive positioning sensor (100) according to any of the previous claims, wherein the Tx connection (1017) and Tx connection (1018) are connected to an application-specific integrated circuit.

7. Inductive positioning sensor (100) according to any of the previous claims, wherein the application-specific integrated circuit is adapted to perform signal processing, excitation, demodulation and the amplification of induced voltage signals on the at least two receiver coils (102, 103).

8. Inductive positioning sensor (100) according to any of the previous claims, wherein the set of vias comprise a via (1012) adapted to connect Layer A trace (1021) to Layer B trace (1022).

9. Inductive positioning sensor (100) according to any of the previous claims, wherein the set of vias comprise a via (1013) adapted to connect Layer C trace (1023) to Layer D trace (1024).

10. Inductive positioning sensor (100) according to any of the previous claims, wherein the set of vias comprise a via (1016) adapted to connect Layer B trace (1022) to Layer C trace (1023).