Inductive angle sensor and inductive torque sensor

Abstract

The invention discloses an inductive angle sensor and an inductive torque sensor. An inductive angle sensor comprising: a plurality of inductively coupled transmitter coils (TX1, TX2), together forming an inductively coupled transmitter coil system; a plurality of sets of receiver coils; a plurality of integrated devices (IC1, IC2), each integrated device having a first and a second oscillator pin (LCP1, LCN1; lCP1, LCP2, LCN2), each integrated device having an excitation circuit (321) for providing an alternating signal on its oscillator pin and having an evaluation circuit for evaluating a signal obtained from the set of receiver coils; at least one movable target (412a, 412b) arranged in the vicinity of the receiver coil; wherein each transmitter coil (TX1) has a first end (TX1a) connected to a first oscillator pin (LCP1) of a first integrated device (IC1), and has a second end (TX1b) connected to a second oscillator pin (LCN2) of a subsequent integrated device (IC2).

Description

Technical Field

[0001] The present invention relates generally to the field of inductive angle sensors and inductive torque sensors, and more particularly to inductive angle sensors and inductive torque sensors having at least some fault tolerance. Background Art

[0002] Inductive angle sensors are known in the art. They offer the advantage of being able to measure angular position without physical contact, thereby avoiding mechanical wear, scratches, friction and the like. They typically comprise an excitation coil (also called a "transmitter coil") and a plurality of detection coils (also called "receiver coils") and a coupling element. The excitation coil generates an alternating magnetic field, which is coupled to a receiver coil set depending on the angular position of the coupling element. The signals obtained from the receiver coils are processed in an electronic circuit, and the angular position is determined based on these signals.

[0003] EP 4 198 458 (A1) describes an inductive angle sensor.

[0004] US2010319467 (A1) discloses an inductive torque sensor.

[0005] It is important that the angle sensor or torque sensor functions correctly, in particular in automotive applications, robotic applications and industrial applications, for the safety of personnel or users or operators, and in order to limit material damage. Several degrees of "safety" are known in the art, such as (i) being able to detect an error, but not being able to continue operation if an error is detected; or (ii) being able to detect an error, but continuing to function correctly despite the error, although performance may be reduced (e.g., reduced speed, reduced accuracy, increased power consumption, etc.), or (iii) being able to detect an error and correct the error, and continuing operation as defined.

[0006] There is always room for improvement or substitution. Summary of the invention

[0007] It is an object of embodiments of the present invention to provide an inductive angle sensor having at least some fault tolerance, and / or an inductive torque sensor comprising such an angle sensor.

[0008] Embodiments of the present invention aim to provide an inductive angle sensor and / or an inductive torque sensor with at least some redundancy, for example by providing two integrated devices and two transmitter coils.

[0009] An object of embodiments of the present invention is to provide an inductive angle sensor and / or an inductive torque sensor that is tolerant to various errors (sometimes also referred to as "failure operability"), such as errors related to soldering errors between some of the components of these sensors, such as an unwanted short circuit between two nodes, or an unwanted open circuit between two nodes, or missing or damaged components, such as missing SMD components (e.g., missing capacitors or missing resistors).

[0010] An embodiment of the present invention aims to provide an inductive angle sensor and / or an inductive torque sensor that is tolerant to a short circuit (at least) between two oscillator pins (e.g., LCP1, LCN1) of an integrated device used therein, even if the two oscillator pins of the integrated device used therein are adjacent pins, and preferably also tolerant to other errors.

[0011] An object of embodiments of the present invention is to provide an inductive angle sensor and / or an inductive torque sensor without increasing the number of pins of an integrated device used therein and / or without re-layout of a semiconductor substrate of the integrated device used therein.

[0012] It is an object of embodiments of the present invention to provide an inductive sensor and / or a torque sensor suitable for use in an automotive, robotic or industrial environment.

[0013] These objects are achieved by embodiments of the present invention.

[0014] According to a first aspect, the present invention provides an inductive angle sensor, comprising: a first transmitter coil (e.g., TX1); a second transmitter coil (e.g., TX2), the second transmitter coil (e.g., TX2) being inductively coupled to the first transmitter coil (e.g., TX1), the first transmitter coil and the second transmitter coil together forming an inductively coupled transmitter coil system; a first group of receiver coils (e.g., RX1a, RX1b, RX1c), the first group of receiver coils comprising at least two or at least three receiver coils; a second group of receiver coils (e.g., RX2a, RX2b, RX2c), the second group of receiver coils The receiver coil comprises at least two or at least three receiver coils; a first integrated device (e.g., IC1) having a first oscillator pin (e.g., LCP1) and a second oscillator pin (e.g., LCN1) and having an excitation circuit for providing an alternating signal on its oscillator pins (e.g., LCP1, LCN1); and having a plurality of receiver pins connected to a first group of receiver coils (e.g., RX1a, RX1b, RX1c); and an evaluation circuit for evaluating the signal obtained from the first group of receiver coils; a second integrated device (e.g., IC2) having a first oscillator pin (e.g., LCP2) and a second oscillator pin (e.g., LCN2), and having an excitation circuit for providing an alternating signal on its oscillator pins (e.g., LCP2, LCN2); and having a plurality of receiver pins connected to a second set of receiver coils (e.g., RX2a, RX2b, RX2c), and an evaluation circuit for evaluating the signals obtained from the second set of receiver coils; at least one movable target for providing inductive coupling between the inductively coupled transmitter coil system and each set of receiver coils; wherein the first transmitter coil (e.g., TX1) has an inductively coupled first oscillator pin operably connected to the first integrated device (e.g., The transmitter coil (e.g., TX2) has a first end (e.g., TX1a) operably connected to a first oscillator pin (e.g., LCP1) of a second integrated device (e.g., IC1) and has a second end (e.g., TX1b) operably connected to a second oscillator pin (e.g., LCN2) of a second integrated device (e.g., IC2); and the second transmitter coil (e.g., TX2) has a first end (e.g., TX2a) operably connected to the first oscillator pin (e.g., LCP2) of the second integrated device (e.g., IC2) and has a second end (e.g., TX2b) operably connected to the second oscillator pin (e.g., LCN1) of the first integrated device (e.g., IC1).

[0015] Fig. 6A Combination Figure 4A or Figure 4B The figure shows an example of such an inductive angle sensor.

[0016] Providing two integrated circuits (ICs), two transmitter coils and two sets of receiver coils is advantageous because in this way hardware redundancy is provided which allows errors to be detected.

[0017] Inductively coupling and further cross-coupling the transmitter coils between two ICs (rather than connecting them between 2 oscillator pins of a single IC) is an advantage because such an arrangement is more robust against certain hardware failures, such as for example:

[0018] i) is robust with respect to a "short circuit connection" between the first pin and the second pin of the first integrated device (e.g., Figure 6B ). This is particularly relevant if these oscillator pins are adjacent pins of an integrated device, and more specifically adjacent pins of a packaged semiconductor device (also referred to as a "chip").

[0019] ii) is robust with respect to a disconnection between the oscillator pin (e.g., LCP1) and the transmitter coil (e.g., TX1), e.g. Figure 6C As shown in the figure.

[0020] An advantage of this solution is that a device package with an increased number of pins is not required (eg there is an extra pin between the two oscillator pins to reduce the risk of such a short circuit).

[0021] In an embodiment, the transmitter coil and the receiver coil are integrated on a single multi-layer printed circuit board (PCB) (eg, a four-layer PCB or a six-layer PCB).

[0022] An advantage of the present invention is that the inductive angle sensor is tolerant to various possible faults, such as: (i) a short circuit between the two oscillator pins of the chip (see e.g. Figure 6B and Figure 7B ), (ii) disconnection between the oscillator pin of the chip and the transmitter coil (see e.g. Figure 6C and Figure 7C ).

[0023] In an embodiment, a first integrated device (e.g., IC1) is a first packaged semiconductor device having a plurality of pins, and wherein a first oscillator pin (e.g., LCP1) and a second oscillator pin (e.g., LCN1) of the first integrated device are adjacent pins of the first packaged semiconductor device; and wherein a second integrated device (e.g., IC2) is a second packaged semiconductor device having a plurality of pins, and wherein a first oscillator pin (e.g., LCP2) and a second oscillator pin (e.g., LCN2) of the second integrated device are adjacent pins of the second packaged semiconductor device.

[0024] In other words, in this embodiment, the first oscillator pin and the second oscillator pin are positioned adjacent to each other without any intervening pins.

[0025] Preferably, the inductance of the second transmitter coil is substantially equal to the inductance of the first transmitter coil.

[0026] In an embodiment, each of the first and second transmitter coils (eg, TX1 , TX2 ) has an inductance in the range from 3.0 to 5.0 μH.

[0027] The coupling factor or coupling coefficient (k) between the first transmitter coil and the second transmitter coil is preferably a value in the range from 0.5 to 1.0, or from 0.6 to 1.0, or from 0.7 to 1.0, or from 0.8 to 1.0, or from 0.9 to 1.0.

[0028] In an embodiment, the inductive angle sensor further includes a first capacitor (e.g., C1p) having a first end connected to a first oscillator pin (e.g., LCP1) of a first integrated device (e.g., IC1), and a second end connected to a first reference voltage; and further includes a second capacitor (e.g., C1n) having a first end connected to a second oscillator pin (e.g., LCN1) of the first integrated device (e.g., IC1), and a second end connected to a second reference voltage; and further includes a third capacitor (e.g., C2p) having a first end connected to a first oscillator pin (e.g., LCP2) of a second integrated device (e.g., IC2), and a second end connected to a third reference voltage; and further includes a fourth capacitor (e.g., C2n) having a first end connected to a second oscillator pin (e.g., LCN2) of the second integrated device (e.g., IC2), and a second end connected to a fourth reference voltage.

[0029] In an embodiment, the first reference voltage, the second reference voltage, the third reference voltage and the fourth reference voltage are equal, for example formed by a ground plane of a printed circuit board, but this is not absolutely necessary and the second terminal can also be connected to another stable voltage (eg, VDD).

[0030] The first TX coil TX1 and the capacitors C1p and C2n connected thereto form a first LC oscillator having a first resonant frequency. The second TX coil TX2 and the capacitors C2p and C1n connected thereto form a second LC oscillator having a second resonant frequency. Preferably, the first resonant frequency and the second resonant frequency are the same, but the present invention will still function if the ratio of the first resonant frequency to the second resonant frequency is a value in the range of, for example, from 0.90 to 1.10, or from 0.95 to 1.05.

[0031] In an embodiment, each of the first and second integrated devices (eg, IC1 , IC2 ) further includes an internal current limiting mechanism for limiting current allowed to flow into or out of the integrated devices via the first and second oscillator pins.

[0032] This type of circuit is particularly useful in the event that a capacitor is shorted.

[0033] In an embodiment, a first evaluation circuit is configured to determine a first angle value (e.g., α1) based on signals obtained from a first set of receiver coils (e.g., RX1a, RX1b, RX1c), and a second evaluation circuit is configured to determine a second angle value (e.g., α2) based on signals obtained from a second set of receiver coils (e.g., Rx2a, RX2b, RX2c).

[0034] Depending on the application, the first angle and the second angle may be used, for example, to determine an absolute angle value in the range of 360°. In another application, the first angle and the second angle may be used, for example, to determine an elastic deformation of a torsion bar due to a torque applied thereto.

[0035] In an embodiment, a center position (e.g., middle) of a first transmitter coil (e.g., TX1) is electrically connected to a center position (e.g., middle) of a second transmitter coil (e.g., TX2) via a short circuit (e.g., copper trace) or via a resistor.

[0036] Or in other words, in this embodiment (for example, Figure 8 ), a position near the middle of the first transmitter coil is electrically connected to a position near the middle of the second transmitter coil through a resistor. The resistance of the resistor can be very small, for example, less than 40 ohms, or less than 20 ohms, or less than 10 ohms, or less than 5 ohms, or less than 1.0 ohm.

[0037] An advantage of this embodiment is that it reduces or eliminates the risk of a non-oscillating state, or in other words, helps achieve an oscillating state during start-up.

[0038] In an embodiment, the inductive angle sensor further includes one or both of the following: a first resistor (e.g., R1) having a first end (e.g., R1a) connected to a first oscillator pin (e.g., LCP1) of a first integrated device (e.g., IC1) and having a second end (e.g., R1b) connected to a first oscillator pin (e.g., LCP2) of a second integrated device (e.g., IC2); a second resistor (e.g., R2) having a first end (e.g., R2a) connected to a second oscillator pin (e.g., LCN1) of the first integrated device (e.g., IC1) and having a second end (e.g., R2b) connected to a second oscillator pin (e.g., LCN2) of the second integrated device (e.g., IC2).

[0039] Adding cross-coupled resistors is advantageous because such an arrangement further improves robustness against hardware failures, for example in the case where one end of the transmitter coil is not connected to the first oscillator pin or the second oscillator pin of the integrated device, e.g. FIG. 7C to FIG. 7H As shown in the figure.

[0040] Another advantage of adding cross-coupled resistors is that the risk of both LC oscillators falling into a stable state is reduced and start-up leading to an oscillatory state is more easily achieved.

[0041] One resistor was found to be sufficient to avoid the non-oscillatory state, but the use of two resistors provides better redundancy and provides complete symmetry of the circuit.

[0042] An advantage of this embodiment is that the inductive angle sensor is further tolerant to any of the following faults:

[0043] iii) Disconnection between the chip's oscillator pin and the capacitor (see e.g. Fig. 7E ),

[0044] iv) A short circuit of a capacitor, or a short circuit between an oscillator pin and ground, or a short circuit between one end of the transmitter coil and ground (see e.g. Figure 7F ),

[0045] v) A short circuit of a resistor, or a short circuit between LCP1 and LCP2, or a short circuit between LCN1 and LCN2 (see e.g. Figure 7G ),

[0046] vi) Disconnection between the oscillator pin and the resistor (see e.g. Figure 7H ).

[0047] In an embodiment, each of the first and second transmitter coils (e.g., TX1, TX2) has an inductance in the range from 3.0 to 5.0 μH, and the first and second resistors (e.g., R1, R2) have a resistance in the range from 30 ohms to 120 ohms, and each of the capacitors (e.g., C1P, C1n, C2p, C2n) has a capacitance in the range from 0.5 nF to 2.0 nF.

[0048] In an embodiment, each of the first integrated device and the second integrated device is configured to perform a test based on the resistance between a first oscillator pin of the first integrated device (e.g., LCP1) and a first oscillator pin of the second oscillator device (e.g., LCP2) to detect the presence or short circuit of a first resistor (e.g., R1); and / or wherein each of the first integrated device and the second integrated device is configured to perform a test based on the resistance between a second oscillator pin of the first integrated device (e.g., LCN1) and a second oscillator pin of the second oscillator device (e.g., LCN2) to detect the presence or short circuit of a second resistor (e.g., R2).

[0049] For example, the test may be performed during startup of the integrated device.

[0050] The test may comprise, for example, applying a predefined voltage on the oscillator pin and measuring the current; or may comprise, for example, the measurement of the time constant when charging or discharging a capacitor through the resistor.

[0051] In an embodiment, each of the first integrated device and the second integrated device (eg, IC1 , IC2 ) is further configured to detect a loss of oscillation on its first oscillator pin and second oscillator pin.

[0052] For example, loss of oscillation may be detected by comparing the frequency of the LC oscillator to another frequency, such as an internal oscillator frequency (eg, an RC oscillator frequency).

[0053] Optionally, the integrated device is further configured to report the loss of oscillation, for example automatically upon detection of the loss of oscillation, or upon request of an external device (eg, an ECU), for example via a serial bus interface.

[0054] In an embodiment, the first and second integrated devices (eg, IC1, IC2) are further configured to determine a frequency value of oscillation on their first and second oscillator pins; and further configured to detect an error based on the frequency value.

[0055] For example, the frequency value determined by the test is whether it is within a first predefined range (or above a first predefined threshold) corresponding to a first operating mode (e.g., "normal operation"), or within a second predefined range (or below the first predefined threshold) corresponding to a second operating mode (e.g., "a mode with degraded accuracy, but still operational").

[0056] Optionally, the device is further configured to test whether the determined frequency is below a second threshold corresponding to a third operating mode (eg "non-oscillating mode").

[0057] Optionally, the integrated device is further configured to report the frequency value or the error, for example automatically after detecting the frequency value or the error, or upon request of an external device (eg, ECU), for example via a serial bus interface.

[0058] In an embodiment, a first set of receiver coils (e.g., RX1a, RX1b, RX1c) are primarily located on a first side of a multi-layer printed circuit board (PCB), and a second set of receiver coils (e.g., RX2a, RX2b, RX2c) are primarily located on a second side of the multi-layer printed circuit board (PCB), the second side being opposite to the first side.

[0059] For example, “primarily located on a particular side” means that a major portion of the conductive traces forming the coil (e.g., at least 60% or at least 70% or at least 80% of the total length of the traces forming the coil) is positioned on that particular side, even if one or more vias and / or “bridges” are formed in another layer of the multilayer PCB.

[0060] In an embodiment, the inductive angle sensor includes a single movable target; and each of the first integrated device and the second integrated device (eg, IC1 , IC2 ) is configured to determine an angular position (eg, α1 , α2 ) of the single movable target.

[0061] In this embodiment, a single movable target is sufficient, but in a variant, two movable targets that can be moved in the same way (e.g., interconnected by a short rigid shaft section) can also be used. In the case of using two movable targets, they preferably have the same periodicity. The constant offset between them can be determined (e.g., during production) and can be compensated.

[0062] This inductive angle sensor is particularly suitable for pedal angle measurement applications, because the same angle is measured twice. (In simple terms: single mechanical target, dual electronics).

[0063] Both angle sensors can be configured to provide the determined angular position to an external processor (e.g., an ECU), which can detect errors by testing the consistency between the first angle and the second angle. In this case, each of the first integrated device and the second integrated device is communicatively connected to the ECU.

[0064] Alternatively or additionally, the first integrated device provides its angular position to the second integrated device, and the second integrated device is configured to detect errors by testing the consistency between the first angle and the second angle. In this case, the first integrated device and the second integrated device are communicatively connected to each other.

[0065] In an embodiment, a first integrated device (e.g., IC1) is configured to determine a first angle value (e.g., α1) of a single movable target; and a second integrated device (e.g., IC2) is configured to determine a second angle value (e.g., α2) of the single movable target; and the inductive angle sensor is further configured to determine the consistency between the first angle value (e.g., α1) and the second angle value (e.g., α2).

[0066] Such an inductive angle sensor may also be referred to as a “redundant angle sensor”.

[0067] The functionality for determining consistency (or for detecting errors) may be implemented in the first integrated device, and / or in the second integrated device, and / or in a third device (eg, an ECU) communicatively connected to the first and second integrated devices.

[0068] In an embodiment, an inductive angle sensor includes a first movable target and a second movable target, the first movable target having a first periodicity (e.g., a first number of leaves), the second movable target having a second periodicity (e.g., a second number of leaves), the second periodicity (e.g., the second number of leaves) being different from the first periodicity (e.g., the first number of leaves); and a first group of receiver coils having a periodicity equal to the first periodicity, and a second group of receiver coils having a periodicity equal to the second periodicity; and a first integrated device (e.g., IC1) is configured to determine a first angular position (e.g., α1) of the first movable target relative to the first group of receiver coils; and a second integrated device (e.g., IC2) is configured to determine a second angular position (e.g., α2) of the second movable target relative to the second group of receiver coils; and the inductive angle sensor is further configured to determine an absolute angular position based on the first angle value (e.g., α1) and the second angle value (e.g., α2).

[0069] This type of inductive angle sensor can also be called an "absolute angle position sensor".

[0070] The functionality of determining the absolute position may be implemented in the first integrated device, and / or in the second integrated device, and / or in a third device (eg, an ECU) communicatively connected to the first integrated device and the second integrated device.

[0071] In an embodiment, the inductive angle sensor further includes an external processor (eg, ECU) communicatively connected to the first integrated device and to the second integrated device.

[0072] According to a second aspect, the present invention also provides a torque sensor, which includes: a torsion bar; an inductive angle sensor according to the first aspect, which includes a first movable target and a second movable target; wherein the first movable target is connected to the torsion bar at a first axial position, and the second movable target is connected to the torsion bar at a second axial position, and the second axial position is spaced apart from the first axial position.

[0073] The torsion bar is elastically deformable.

[0074] A torque sensor can be seen as a special kind of inductive angle sensor, where two different angles can be measured. Such a torque sensor can be used, for example, in steering wheel applications.

[0075] Preferably, the PCB of the torque sensor comprises six layers, and the two TX coils are mainly located in the two center layers.

[0076] In an embodiment, a first integrated device (e.g., IC1) is configured to determine a first angular position (e.g., α1) of a first movable target relative to a first set of receiver coils (e.g., RX1a, RX1b, RX1c); and a second integrated device (e.g., IC2) is configured to determine a second angular position (e.g., α2) of a second movable target relative to a second set of receiver coils (e.g., RX2a, RX2b, RX2c); and the torque sensor is further configured to determine a difference between the first angle value (e.g., α1) and the second angle value (e.g., α2), and to provide the difference, or a value derived from the difference, as a value indicative of the torque to be measured.

[0077] This difference is indicative of the torque applied to the torsion bar.

[0078] According to a third aspect, the present invention further provides an inductive angle sensor, comprising: N inductively coupled transmitter coils (e.g., TX1, TX2, TX3, TX4), the N inductively coupled transmitter coils together forming an inductively coupled transmitter coil system, N being at least three; a plurality of groups (e.g., N groups) of receiver coils, each group of receiver coils comprising at least two or at least three receiver coils; the number N of integrated devices (e.g., IC1, IC2, IC3, IC4), each integrated device having a first oscillator pin and a second oscillator pin (e.g., LCP1, LCN1; LCP2, LCN2; LCP3, LCN3; LCP4, LCN4), and each integrated device having a first oscillator pin and a second oscillator pin (e.g., LCP1, LCN1; LCP2, LCN2; LCP3, LCN3; LCP4, LCN4), and each integrated device having a first oscillator pin and a second oscillator pin; An excitation circuit for providing an alternating signal, and each integrated device has an evaluation circuit for evaluating a signal obtained from a group of receiver coils in a plurality of groups of receiver coils; at least one movable target for providing inductive coupling between an inductively coupled transmitter coil system and a group of receiver coils; wherein each transmitter coil (e.g., TX1, TX2, TX3, TX4) has a first end (e.g., TX1a) operably connected to a first oscillator pin (e.g., LCP1) of a first integrated device (e.g., IC1, IC2, IC3, IC4), and has a second end (e.g., TX1b) operably connected to a second oscillator pin (e.g., LCN2) of a subsequent integrated device (e.g., IC2, IC3, IC4, IC1).

[0079] In an embodiment, the inductive angle sensor further comprises one or both of the following: i) N first resistors (e.g., R1p, R2p, R3p, R4p) having a first end connected to a first oscillator pin (e.g., LCP1, LCP2, LCP3, LCP4) of a first integrated device (e.g., IC1, IC2, IC3, IC4) and having a first end connected to a first oscillator pin (e.g., LCP2, LCP3, LCP4) of a subsequent integrated device (e.g., IC2, IC3, IC4, IC1); LCP4, LCP1); ii) N second resistors (e.g., R1n, R2n, R3n, R4n), the N second resistors having a first end connected to a second oscillator pin (e.g., LCN1, LCN2, LCN3, LCN4) of a first integrated device (e.g., IC1, IC2, IC3, IC4) and having a second end connected to a second oscillator pin (e.g., LCN4, LCN1, LCN2, LCN3) of a previous integrated device (e.g., IC4, IC1, IC2, IC3).

[0080] According to a fourth aspect, the present invention also provides a torque sensor, which includes: a torsion bar; an inductive angle sensor according to the third aspect, which includes a first movable target and a second movable target; wherein the first movable target is connected to the torsion bar at a first axial position, and the second movable target is connected to the torsion bar at a second axial position, and the second axial position is spaced apart from the first axial position.

[0081] In an embodiment, two integrated devices (e.g., IC1, IC2) are configured to determine a first angular position (e.g., α1) of a first movable target relative to a printed circuit board; and two integrated devices (e.g., IC3, IC4) are configured to determine a second angular position (e.g., α2) of a second movable target relative to the printed circuit board; and the torque sensor is further configured to determine a difference between the first angle value (e.g., α1) and the second angle value (e.g., α2), and to provide the difference, or a value derived from the difference, as a value indicative of the torque to be measured.

[0082] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate, and not merely as explicitly set out in the claims. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Fig. 1 shows an example of an inductive sensor arrangement known in the art.

[0084] FIG. 2 shows a variant of the arrangement of FIG. 1 for a target with only three blades, as is known in the art.

[0085] 3 shows a schematic block diagram of an angle sensor system known in the art, which comprises a substrate having a transmitter coil and three receiver coils, a target movable relative to the substrate, and an integrated device connected to the receiver coil and the transmitter coil.

[0086] Figure 4A Shown is a schematic representation of an inductive angle sensor arrangement according to an embodiment of the invention, as may be used in, for example, a torque sensor.

[0087] Figure 4BA schematic representation of another inductive angle sensor arrangement according to an embodiment of the invention is shown, as may be used, for example, for a redundant angle sensor or an absolute angle sensor.

[0088] Figure 5A is a schematic representation of a circuit comprising two integrated devices, each of which is connected to a respective transmitter coil and two capacitors to form a respective LC oscillator circuit.

[0089] Figure 5B Shows Figure 5A A possible failure mode of the circuit is a short circuit between the two oscillator pins LCP1 and LCN1 of the first integrated device.

[0090] Fig. 6A is a schematic representation of a first embodiment of a circuit proposed by the present invention, which can be Figure 4A or Figure 4B Used in inductive angle sensor arrangements.

[0091] Figure 6B Shown, Fig. 6A The circuit is tolerant to a short circuit between the two oscillator pins LCP1, LCN1 of the first integrated device.

[0092] Figure 6C Shown, Fig. 6A The circuit is not tolerant to a disconnection between the oscillator pin (eg, LCP1) of the integrated device and the transmitter coil (eg, TX1).

[0093] Fig. 7A is a schematic representation of a second embodiment of the circuit proposed by the present invention, which can be Figure 4A or Figure 4B Used in inductive angle sensor arrangements.

[0094] Figure 7B Shown, Fig. 7A The circuit is tolerant to a short circuit between the two oscillator pins LCP1, LCN1 of the first integrated device.

[0095] Figure 7C and Fig.7D Shown, Fig. 7A The circuit is tolerant to a disconnection between an oscillator pin (eg, LCP1) of the integrated device and a transmitter coil (eg, TX1).

[0096] Fig. 7E Shown, Fig. 7A The circuit is intolerant of a disconnection between the oscillator pin (eg, LCP1) and the capacitor (eg, C1p) of the integrated device.

[0097] Figure 7F Shown, Fig. 7A The circuit is tolerant to a short circuit of a capacitor (eg, C1p), or to a short circuit between an oscillator pin (eg, LCP1) and ground.

[0098] Figure 7G Shown, Fig. 7A The circuit is tolerant to a short circuit of a resistor (eg, R1).

[0099] Figure 7H Shown, Fig. 7A The circuit is tolerant to a disconnection between the oscillator pin (eg, LCN2) and the resistor (eg, R2).

[0100] Figure 8 is a schematic representation of a third embodiment of the circuit proposed by the present invention, which can be Figure 4A or Figure 4B Used in inductive angle sensor arrangements.

[0101] Fig. 9 is a schematic representation of a fourth embodiment of the circuit proposed by the present invention, which can be Figure 4A or Figure 4B Used in inductive angle sensor arrangements.

[0102] These drawings are only schematic and non-limiting. In the drawings, for illustrative purposes, the size of some of the elements may be exaggerated and not drawn to scale. Any reference numerals in the claims should not be interpreted as limiting the scope. In different drawings, the same or similar reference numerals (e.g., the same module 100) generally refer to the same or similar elements. DETAILED DESCRIPTION

[0103] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0104] The terms first, second, etc. in the specification and in the claims are used to distinguish between similar elements and not necessarily to describe a sequence in time, space, level, or in any other manner. It should be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in a sequence different from that described or illustrated herein.

[0105] The terms top, bottom, etc. in the specification and claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in orientations other than those described or illustrated herein.

[0106] It should be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Thus, the term should be interpreted as specifying the presence of the stated features, integers, steps or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of component A and component B. It means that for the present invention, the only relevant components of the device are A and B.

[0107] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may. Furthermore, in one or more embodiments, as would be apparent to one of ordinary skill in the art from this disclosure, the particular features, structures, or characteristics may be combined in any suitable manner.

[0108] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects, the various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than those explicitly recited in each claim. On the contrary, as reflected in the appended claims, the inventive aspects lie in fewer features than all of the features of a single preceding disclosed embodiment. Thus, the claims appended to the Detailed Description are hereby expressly incorporated into the Detailed Description, with each claim itself representing a separate embodiment of the invention.

[0109] In addition, although some embodiments described herein include some features included in other embodiments but do not include other features included in these other embodiments, the combination of features of different embodiments is intended to fall within the scope of the present invention and form different embodiments as will be understood by those skilled in the art. For example, in the appended claims, any of the embodiments claimed for protection may be used in any combination.

[0110] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be implemented without these specific details. In other examples, well-known methods, structures, and techniques are not shown in detail to avoid confusion in understanding this description.

[0111] In this document, the terms "excitation coil" and "transmitter coil" are meant to mean the same thing.

[0112] In this document, the terms "receiver coil" and "detection coil" are used synonymously.

[0113] In this document, the terms "coupling element" and "target" and "rotor" are intended to mean the same thing.

[0114] In this document, the "periodicity" of a movable object may refer to the number of lobes or teeth.

[0115] In this document, the "mechanical angle" of a movable target may be calculated as the "electrical angle" of the movable target divided by its periodicity.

[0116] In this document, "SMD component" stands for "surface mount device" component, for example, SMD capacitor or SMD resistor.

[0117] In this document, when a "chip" or "sensor chip" is mentioned, it means an "integrated device" unless it is clear from the context that something else is meant.

[0118] The present invention relates to an inductive angle sensor and / or an inductive torque sensor having at least some fault tolerance, which means that even in the event of certain errors (such as, for example, welding errors, short circuit connections, disconnections (open circuits) etc.), the angle sensor or torque sensor will continue to function normally (but possibly with reduced accuracy).

[0119] The inductive angle sensor proposed by the present invention can be used in various applications, such as, for example, a redundant angle sensor, an absolute position sensor, or a torque sensor.

[0120] Reference is now made to the drawings.

[0121] FIG. 1 shows an example of an inductive sensor arrangement, comprising: a substrate 110 (e.g., a printed circuit board, PCB) comprising a transmitter coil and a plurality of receiver coils; and a target 112 (e.g., a metal target) which is rotatable relative to the substrate. In the example shown in FIG. 1 , the transmitter coil Tx has three circular windings and the target 112 has five lobes (or lobes or blades) which are spaced apart by 360° / 5=72°. The principle of operation of such an inductive sensor arrangement is well known in the art and therefore does not need to be explained in detail here. It can be said that typically an integrated circuit (not shown in FIG. 1 , but see, for example, FIG. 3 ) provides an excitation signal to a transmitter coil laid out on a printed circuit board (PCB). The transmitter coil is part of an LC oscillator circuit. The integrated circuit provides an AC signal to the transmitter coil, which induces eddy currents in a conductive (e.g., metal) target 112, which in turn induces an AC current in the receiver coil depending on the angle or position of the target. The receiver coil is also laid out on the PCB. The signal can be decoded by an integrated circuit to determine the angular position of the target.

[0122] FIG. 2 shows a variation of the arrangement of FIG. 1 for a target with only three blades.

[0123] 3 shows a schematic block diagram of an angle sensor system 300, which includes: a substrate (e.g., a PCB) having a transmitter coil TX and three receiver coils Rx1, Rx2, Rx3; a target 312, which is movable relative to the substrate; and an integrated device 320, which is connected to the transmitter coil TX and to the receiver coils. The integrated circuit 320 can amplify the three received signals and can demodulate the envelope from the carrier signal to generate three baseband signals, and the angular position of the rotor can be derived from the three baseband signals.

[0124] Figures 1 to 3 are known from EP4198458 (A1 ) and are provided here primarily as background information and in order to illustrate potential problems with the prior art.

[0125] One such problem is that the angle sensor will no longer function in the event that the oscillator pins LCP and LCN of the integrated device 320 of Figure 3 are inadvertently shorted. This risk has an increased likelihood in the event that the two oscillator pins LCP and LCN are adjacent pins of the integrated device 320.

[0126] The inventors of the present invention were asked to provide a solution to this problem. More specifically, they were asked to provide an inductive angle sensor and / or an inductive torque sensor that will continue to operate even if the LCP and LCN pins of the integrated device are short-circuited. Preferably, of course, a cheap and / or compact solution is preferred.

[0127] A simple solution is to completely duplicate the hardware, for example by providing twice the hardware of FIG. 3 , i.e., two printed circuit boards (PCBs), each having a transmitter coil and multiple receiver coils; an integrated device; and a movable target, but this solution is not compact and is not cheap, and a cheaper solution is desired.

[0128] Figure 4A A schematic representation of an inductive angle sensor system 400a proposed by the present invention is shown, comprising a single PCB 410 and two movable targets 412a, 412b located on opposite sides of the PCB.

[0129] The first target 412a has a first periodicity (e.g., a first number of leaves), and the first set of receiver coils RX1a, RX1b, RX1c also has the first periodicity. The second target 412b has a second periodicity (e.g., a second number of leaves), and the second set of receiver coils RX2a, RX2b, RX2c also has the second periodicity. If the periodicity is N (e.g., N=5), the angular position of the target has a mechanical measurement range of 360° / N=72°.

[0130] The first periodicity is preferably different from the second periodicity.This provides the advantage of reducing crosstalk between signals caused by the first target and the second target.

[0131] The PCB may be a four-layer PCB or a six-layer PCB, or may include more than six layers.

[0132] PCB 410 includes a first transmitter coil TX1, and a first set of receiver coils RX1a, RX1b, RX1c, and a first integrated device IC1; and a second transmitter coil TX2, and a second set of receiver coils RX2a, RX2b, RX2c, and a second integrated device IC2.

[0133] Preferably, the two integrated devices IC1 , IC2 are mounted on the same side of the PCB 410 .

[0134] Preferably, the first set of receiver coils RX1a, RX1b, RX1c is mainly located on the first side of the multi-layer PCB (at Figure 4AIn the example of FIG. 4 , the receiver coils RX2a, RX2b, RX2c are mainly located on the left side, closer to the target 412a), and the second group of receiver coils RX2a, RX2b, RX2c are mainly located on the second side of the multilayer PCB, the second side being opposite to the first side (at Figure 4B In the example of FIG. 4 , it is mainly located on the right side, closer to the target 412 b).

[0135] For example, “primarily located on a particular side” means that a major portion of the conductive traces forming the coil (e.g., at least 60% or at least 70% or at least 80% of the total length of the traces forming the coil) is positioned on that particular side, even if one or more vias and / or “bridges” are formed in another layer of the multilayer PCB.

[0136] In an embodiment, the PCB 410 of the torque sensor includes six layers, and the two TX coils are mainly located in the two center layers.

[0137] exist Figure 4A In the example of FIG. 4 , a first target 412 a and a second target 412 b are connected at two different axial positions of a torsion bar 441. When a torque is applied to the torsion bar, the torsion bar is elastically deformable. The torsion bar 441 may be connected to an input shaft 442 at one end and may be connected to a second shaft 443 at its other end. When a torque is applied between the first shaft 442 and the second shaft 443, the target 412 a will move slightly relative to the target 412 b. This angular difference can be measured and the torque can be derived from this angular offset, for example by using a mathematical formula or a lookup table.

[0138] Figure 4B Another schematic representation of the inductive angle sensor system 400b proposed by the present invention is shown, which can be regarded as Figure 4A The embodiment of the present invention is a variation of system 400a of FIG. 4. The primary difference is that both the first target 412a′ and the second target 412b′ are connected to a rigid shaft 444 that has negligible deformation between the axial locations at which the targets are connected. When torque is applied to the shaft 444, the first target 412a′ and the second target 412b′ do not substantially rotate relative to each other.

[0139] In the case where the first periodicity (of the first target and the first set of receiver coils) is equal to the second periodicity (of the second target and the second set of receiver coils), Figure 4B The angle sensors of can be used as redundant inductive angle sensors, and both chips IC1 and IC2 will measure substantially the same angle of the target, and thereby measure the angle of the axis relative to the PCB. Note that in this case, one of the movable targets 412a', 412b' can be omitted.

[0140] In the case where the first periodicity is different from the second periodicity (e.g., one more or one less), Figure 4B The angle sensor can be used as an absolute angle sensor (eg by applying the non-number principle). By taking into account the two angle values, a unique position of the shaft in the 360° measuring range can be determined.

[0141] Figure 4A and Figure 4B A possible mechanical arrangement of the target and PCB 410 is shown, which includes transmitter coils TX1, TX2 and a first set of receiver coils (RX1a, RX1b, RX1c) and a second set of receiver coils, but the problem of how to make the angle sensor fault-tolerant has not been solved. This will be discussed below.

[0142] exist Figure 4A and Figure 4B In the embodiment shown in , IC1 is connected to a first set of 3 receiver coils RX1a, RX1b, RX1c and IC2 is connected to a second set of 3 receiver coils RX2a, RX2b, RX2c, but this is not absolutely necessary and it is also possible to use only two receiver coils per set.

[0143] Figure 5A Schematic and simplified representation of a simple implementation with twice the hardware of FIG. 3 . Figure 5A A circuit 540 is shown comprising two integrated devices, each of which is connected to a respective transmitter coil and two capacitors to form two respective LC oscillator circuits. Figure 5A Shown in.

[0144] Figure 5A The circuit 540a comprises a first integrated device IC1 having two oscillator pins LCP1, LCN1 connected to opposite ends TX1a, TX1b of a first transmitter coil TX1, and a capacitor C1p connected between the first oscillator pin LCP1 and a reference voltage (in this example: ground), and a capacitor C1n connected between the second oscillator pin LCN1 and a reference voltage (in this example: ground), but other reference voltages may also be used. The two reference voltages may also have different values ​​(e.g., C1p may be connected between LCP1 and the supply voltage, and C1n may be connected between LCN1 and ground).

[0145] Figure 5AThe circuit 540a further comprises a second integrated device IC2 having two oscillator pins LCP2, LCN2 connected to opposite ends TX2a, TX2b of the second transmitter coil TX2, and a capacitor C2p connected between the first oscillator pin LCP2 and a reference voltage (in this example: ground), and a capacitor C2n connected between the second oscillator pin LCN2 and a reference voltage (in this example: ground), but other reference voltages may also be used. The two reference voltages may have different values, and these values ​​may even be different from the reference voltages applied to C1p and C1n.

[0146] The two transmitter coils TX1, TX2 are laid out on the PCB in a tightly coupled manner. Preferably, the coupling coefficient (k) is between 0.9 and 1.0. Figure 5A In the schematic diagram of , transmitter coils TX1 and TX2 are inductively coupled, as schematically indicated by the dots, arrows and coupling factor “k.” According to notation known in the art, the dots represent the winding direction of the coils and thus the polarity.

[0147] In dual IC applications, the common LCO frequency can then be calculated or estimated using the following formula:.

[0148]

[0149] This approximation is valid for values ​​of k equal to 1.0 or approximately equal to 1.0.In normal operation, the two LCOs will ideally oscillate at this same frequency, with the same phase and the same amplitude.

[0150] Figure 5B Shows something like Figure 5A 540a, but with an unintentional (or unexpected) short circuit 540b added between LCP1 and LCN1 of IC1, and the diagram shows Figure 5A The circuit 540a proposed in is not robust with respect to a short circuit between LCP1 and LCN1 (schematically indicated by the black line and the star symbol). If a fault occurs in the field, resulting in a short circuit between the oscillator pins LCP1 and LCN1 of IC1, the LCO of the second integrated device IC2 is also loaded by the short circuit through the impedance transformation of the mutually coupled inductors. Eventually, the oscillation of both LCOs will stop and neither integrated device will be able to measure the angle. This would be considered a "single point failure", which is (of course) undesirable. For example, during actual use of the product, especially if the pins LCP1 and LCN1 are adjacent pins, such a short circuit may occur due to solder wear of the pins LCP1 and LCN1 of the integrated device IC1 on a PCB (not shown).

[0151] Fig. 6Ais a schematic and simplified representation of a first embodiment of a circuit 640a proposed by the present invention, which may be Figure 4A The inductive angle sensor arrangement 400a or Figure 4B 400b, or its variants.

[0152] The inventors have conceived of connecting the first transmitter coil TX1 between an oscillator pin (e.g., LCP1) of the first integrated device IC1 and an oscillator pin (e.g., LCN2) of the second integrated device IC2 instead of between the two oscillator pins LCP1, LCN1 of IC1, and similarly, connecting the second transmitter coil TX2 between the oscillator pin LCP2 of the second integrated device IC2 and the oscillator pin LCN1 of the first integrated device IC1 instead of between the two oscillator pins LCP2, LCN2 of IC2. When connected in this way, the first transmitter coil TX1 and the second transmitter coil TX2 together form an "inductively coupled transmitter coil system" that can be excited by IC1 or by IC2 or by both. The winding direction of the transmitter coils TX1, TX2 (and thus the polarity of the transmitter coils TX1, TX2) is preferably selected so that the coils are arranged in an anti-parallel manner, for example, as Fig. 6A Such an anti-parallel connection can be selected if IC1 and IC2 are the same integrated device or have at least the same circuit for driving the transmitter coil. If one of the ICs has an opposite signal behavior for driving the transmitter coil, the coils can be arranged in parallel.

[0153] As indicated, the two transmitter coils TX1 , TX2 are inductively coupled with a coupling factor (k) which preferably has a value in the range from 0.9 to 1.0.

[0154] Surprisingly, it was found that under "normal operation" (eg, steady state operation and no fault conditions), the two LCOs (the first LCO formed by C1p, TX1, C2n; and the second LCO formed by C1n, TX2, C2p) will operate as Figure 5A The same oscillation frequency oscillates together in a push-pull manner, but in which a virtual ground (schematically indicated by a grey ground symbol) is formed in the middle of each transmitter coil TX1 , TX2 .

[0155] Figure 6B Shows something like Fig. 6A 640a, but with an unintentional (or unexpected) short circuit 640b added between LCP1 and LCN1 of IC1, and the diagram shows Fig. 6AThe circuit 640a of is tolerant to a short circuit connection (schematically indicated by a black line and a star symbol) between the two oscillator pins LCP1, LCN1 of the first integrated device IC1. In fact, if LCP1 is shorted to LCN1, it will only eliminate the oscillation on the pins LCP1, LCN1 of the first integrated device IC1, but the second integrated device IC2 will still be able to oscillate its pins LCN2, LCP2 at a certain frequency, which can then be calculated or estimated using the following formula:.

[0156]

[0157] This approximation is valid for values ​​of k equal to or approximately equal to 1.0.

[0158] When LCP1 and LCN1 are short-circuited, the "inductively coupled transmitter coil system" can no longer be excited by IC1, but it can still be excited by IC2, causing an alternating current to flow through TX1 and TX2, which causes an alternating magnetic field through the two sets of receiver coils. The alternating magnetic field is modulated by the corresponding target, allowing the two integrated devices IC1 and IC2 to determine the corresponding angle.

[0159] Note that the virtual ground is now no longer located in the middle of the transmitter coil, but has been shifted to the location of the short itself (as schematically indicated by the grey ground symbol), so the capacitors C1p, C1n connected to the short do not play a major role in the value of the LCO frequency.

[0160] Comparing formula [2] with formula [1] shows that Figure 6B The LCO frequency of the circuit 640b in which LCP1 and LCN1 are short-circuited is reduced by about (about 1.4) times, but this is enough to keep the app running, albeit with potentially degraded accuracy.

[0161] In an embodiment, the integrated devices IC1, IC2 are further configured to detect a loss of oscillation on IC1 and / or to detect or measure a frequency (or frequency change) on IC2, and to report this information or condition to, for example, an external processor (not shown) communicatively connected to the integrated devices IC1, IC2.

[0162] Figure 6BIt is shown that circuit 640b continues to function normally even in the case where pins LCP1 and LCN1 are shorted. Similar reasoning can be provided for the case where pins LCP2 and LCN2 are shorted (but LCP1 and LCN1 are not shorted). In this case, the oscillations on pins LCP2 and LCN2 will stop, but the oscillations on pins LCP1 and LCN1 will continue, so the inductively coupled transmitter coil system can still be excited and both integrated devices can determine angular position, although the accuracy may be degraded.

[0163] Figure 6C Shows something like Fig. 6A A circuit 640c of the circuit 640a but in which the oscillator pin LCP1 is not connected to the first transmitter coil TX1. Figure 6C Shows Fig. 6A Circuit 640a of FIG. 6 is intolerant of a disconnection (or "open circuit") between the oscillator pin of the integrated device and the transmitter coil, which in the example shown is between LCP1 of IC1 and the first end TX1a of the transmitter coil TX1, but the same reasoning is true for a disconnection between TX1 and LCN2, and for a disconnection between TX2 and LCP2, and for a disconnection between TX2 and LCN1. Figure 6C In the circuit 640c, since the oscillation current path is interrupted, both LCOs will stop oscillating. Figure 6C It shows Fig. 6A An example of a "single point failure" in circuit 640a that will not allow the circuit to continue to operate (or in other words, will not result in "fail-operational" behavior). For example, during actual use, such an "open circuit" may occur due to wear of connections within, for example, one or two conductive layers on a PCB.

[0164] Fig. 7A is a schematic representation of a second embodiment of the circuit 740a proposed by the present invention, which can be used in Figure 4A The inductive angle sensor arrangement 400a or Figure 4B 400b, or its variants.

[0165] Fig. 7A The circuit 740a can be viewed as Fig. 6A A variation of circuit 640 is provided, which adds two cross-coupled resistors, namely a first resistor R1 connected between LCP1 of the first chip IC1 and LCP2 of the second chip IC2, and a second resistor R2 connected between LCN1 of the first chip IC1 and LCN2 of the second chip IC2.

[0166] and Fig. 6A Similar to the circuit 640a, it is found that Fig. 7A In circuit 740a of FIG. 1 , under “normal operation” (eg, steady-state operation and no fault conditions), the two LCOs will operate in parallel with Fig. 6A The configuration of the same oscillation frequency oscillates together in a push-pull manner, wherein a virtual ground is formed in the middle of each transmitter coil TX1, TX2. In fact, under "normal operation", substantially no current flows through the resistors R1, R2, because the two LCOs have the same amplitude and phase, whereby the potential difference across the resistors R1 and R2 is always zero, and therefore the resistor values ​​R1 and R2 do not degrade the Q factor.

[0167] Figure 7B Shows something like Fig. 7A , but with an unintentional (or unexpected) short circuit 740b added between LCP1 and LCN1 of IC1, and the diagram shows Fig. 7A The circuit 740a of FIG. 740 is tolerant to a short circuit connection between the two oscillator pins LCP1, LCN1 of the first integrated device IC1. When LCP1 is shorted to LCN1, it will eliminate the oscillation on the pins LCP1, LCN1 of the first integrated device IC1, but the second integrated device IC2 will still be able to oscillate its pins LCN2, LCP2. Due to the short circuit, the second integrated device IC2 will see the resistors R1, R2 in parallel with the transmitter coil. This will degrade the Q factor and cause an increase in current consumption. In this case, relatively large values ​​of R1 and R2 are desirable. Since the configuration is completely symmetrical, a short circuit between the oscillator pins LCP2 and LCN2 of IC2 (in the absence of a short circuit between LCP1 and LCN1) will cause the same effect.

[0168] Figure 7C Shows something like Fig. 7A 740a, but with an unintentional or unexpected disconnection between the oscillator pin of the integrated device and the transmitter coil 740c, and the diagram shows Fig. 7A Line 740a is tolerant to such a single failure.

[0169] In the example shown, the oscillator pin LCP1 is disconnected from the transmitter coil TX1. Due to this disconnection, no current can flow through TX1, and the first integrated device IC1 sees the load (between its oscillator pins) as a series connection of R1 and TX2, and the second integrated device IC2 sees the load (between its oscillator pins) as a series connection of R2 and TX2. This degrades the Q factor and causes increased current consumption. In this case, relatively small values ​​of R1 and R2 are desirable. For simplicity, assuming R1=R2=0, the resulting oscillation frequency can be estimated using the following formula:

[0170]

[0171] This actually means that there is no frequency change because the effective inductance is halved and the effective capacitance is doubled. However, in reality, the resistor value is not zero, the resonant frequency is lowered, the current consumption is increased, and the Q factor is degraded.

[0172] because Figure 7B and Figure 7C Each of the cases shown in may occur in practice, and both degrade the Q factor and lead to an increase in current consumption, and one case tends to favor large resistance values, while the other tends to favor low resistance values, so a compromise needs to be found. A skilled person having the benefit of the present disclosure can easily find suitable values ​​for R1 and R2 by experiment. But as a rule of thumb, if the transmitter coil has an inductance in the range from 3.0 to 5.0 μH (e.g., equal to about 4.0 μH), and if the capacitor has a value of about 1 nF, so that the resonant frequency is about 2.5 MHz, then the resistors R1 and R2 may have a resistance in the range from 30 to 120 ohms, or from 45 to 90 ohms, or from 50 to 70 ohms. But, of course, the invention is not limited to this example, and solutions with other values ​​for the transmitter coil, and for the capacitor, and for the resonant frequency, and for the resistors may also be used.

[0173] Fig.7D Shows something like Fig. 7A 740d of the circuit 740a of FIG. 1 but with an unintentional or unexpected open solder joint at an oscillator pin (eg, LCP1), and FIG. Fig. 7A Circuit 740a is tolerant to such a single failure.

[0174] Surprisingly, in this case, the frequency of both oscillators (one formed by C1p, TX1, C2n; the other formed by C2p, TX, C1n) does not change substantially, since there is no change in the LC configuration. It was found that the resistor values ​​R1, R2 do not significantly reduce the Q factor in this case. A side effect is a change in the current distribution of the two LCOs, where one LCO with an open pin (in the example: IC1) now provides less oscillating current than the other LCO. The integrated devices IC1, IC2 can be configured for detecting this difference, and for reporting such detection to, for example, an external controller. Since the configuration is completely symmetrical, a single open solder joint on any of the oscillator pins (LCP1, LCN1, LCP2, LCN2) will cause the same effect.

[0175] Fig. 7E Shows something like Fig. 7A740e of the circuit 740a of FIG. 740a, but one of the capacitors (eg, C1p) has an unintentional or unintended open solder joint, and the diagram shows Fig. 7A Circuit 740a is tolerant to such a single failure.

[0176] Since the LC configuration changes due to this "opening", the frequency will also change. This situation is more complicated to analyze, but for simplicity, assuming R1 = R2 = 0, the resulting oscillation frequency can be estimated in a first-order approximation using the following formula:

[0177]

[0178] This means that the LCO frequency will increase approximately (about 1.2) times, but the application will continue to function normally, although accuracy may be degraded.

[0179] like Fig.7D As shown, there is a slight redistribution of the current contribution from each LCO, but in this case, the resistor values ​​do not significantly reduce the Q factor. The integrated devices IC1, IC2 can be configured to detect such frequency difference and / or such difference in current contribution, and to report such detection to, for example, an external controller (not shown) communicatively connected to the integrated devices IC1, IC2. Since the configuration is completely symmetrical, a single open solder joint on any of the capacitors C1p, C1n, C2p, C2n will cause the same effect.

[0180] Figure 7F Shows something like Fig. 7A 740a, but with an unintentional or unintended short across one of the capacitors 740f, and the diagram shows Fig. 7A The circuit 740a is tolerant to such a single failure. Figure 7F In the example of , the terminals of C1p are shorted, effectively connecting LCP1 to ground. Since the LC configuration is changed by this short circuit, the oscillation frequency will also change.

[0181] This situation is more complex to analyze, but for simplicity, assuming R1 = R2 = 0, the resulting oscillation frequency can be estimated to a first order approximation using the following formula:

[0182]

[0183] This means that the LCO frequency will be reduced by approximately (about 1.4) times, the application will continue to function normally, although accuracy may be degraded.

[0184] Unlike the previous case, a short circuit of one capacitor to ground may result in increased current consumption of both LCOs, which can be mitigated by the internal current limiting mechanism inside the integrated devices IC1, IC2.

[0185] The integrated device may be configured to detect such a frequency difference and / or such an increase in current contribution, and to report such detection to, for example, an external controller (not shown) communicatively connected to the integrated device. Since the configuration is completely symmetrical, a single short circuit across any of the capacitors C1p, C1n, C2p, C2n will cause the same effect.

[0186] Figure 7G Shows something like Fig. 7A 740a, but with an unintentional or unintended short across one of the capacitors 740g, and the diagram shows Fig. 7A The circuit 740a is tolerant to such a single failure. Figure 7G In the example of FIG. 1 , terminals R1a and R1b of R1 are short-circuited.

[0187] Since the LC configuration is not affected by this short circuit, and since there is no voltage across the resistor anyway under normal conditions, the LCO frequency, amplitude and current consumption do not change.

[0188] Although this single fault does not have a noticeable impact, it is nevertheless worthwhile to detect and report this fault in order to reduce the risk and consequences of a double or triple fault. In an embodiment, the integrated devices IC1, IC2 are configured to detect the presence of the correct resistor values ​​for R1 and R2, for example during a start-up check. Such a test may include, for example: applying a predefined voltage on the oscillator pin and measuring the current; or may include, for example, the measurement of the time constant when charging or discharging a capacitor through the resistor. Since the configuration is completely symmetrical, a single short circuit across any of the resistors R1, R2 will cause the same effect.

[0189] Figure 7H Shows something like Fig. 7A 740a of the circuit 740a of FIG. 740b but with an unintentional or unexpected disconnected or open solder joint between the oscillator pin (eg, LCN2) and one of the resistors (eg, R2), and FIG. Fig. 7A Circuit 740a is tolerant to such a single failure.

[0190] Since the LC configuration is not affected by this disconnection and since there is no voltage across the resistors R1 , R2 anyway under normal conditions, the LCO frequency, amplitude and current consumption do not change.

[0191] Again, although this single fault does not have a noticeable impact, it is worth detecting and reporting this fault anyway in order to reduce the risk and consequences of a double or triple fault. Since the configuration is completely symmetrical, a single disconnection or open solder joint between any of the oscillator pins LCP1, LCN1, LCP2, LCN2 and the associated resistor R1, R2 will cause the same effect.

[0192] Figure 8 is a schematic representation of a third embodiment of the circuit 840 proposed by the present invention, which can be Figure 4A The inductive angle sensor arrangement 400a or Figure 4B 400b, or its variants.

[0193] Figure 8 The circuit 840 can be viewed as Fig. 6A A variation of circuit 640 in which a low resistance connection is added between the center taps of the two transmitter coils TX1, TX2, for example through a resistor R3, or through a PCB layout trace, the resistor R3 preferably having a resistance value of less than 20 ohms, or less than 10 ohms, or less than 5 ohms, or even less than 1 ohm.

[0194] Figure 8 The circuit 840 provides advantages over Fig. 7A Advantages of circuit 740: no discrete resistors R1, R2 need to be mounted on the PCB (ie easier to produce and with a lower component count), but this may result in larger frequency deviations in some of the failure modes mentioned above.

[0195] In addition, the circuit 840 is tolerant to the above-mentioned faults, for example, FIG. 7B to FIG. 7F As shown in the figure.

[0196] It is worth noting that using Fig. 7A The technology and utilization of the two resistors R1, R2 arranged as shown in the figure Figure 8 The techniques of the single resistor R3 of the arrangement illustrated in can function independently, but can also be combined.

[0197] Fig. 9 is a schematic representation of a fourth embodiment of the circuit 940 proposed by the present invention, which can be Figure 4A The inductive angle sensor arrangement 400a or Figure 4B Although not explicitly shown, each IC can be connected to a set of 2 or 3 receiver coils.

[0198] Circuit 940 can be viewed as Fig. 7AA variation of circuit 740 of , but circuit 940 has four integrated devices IC1, IC2, IC3, IC4 instead of just two, and has four transmitter coils TX1, TX2, TX3, TX4, and has a first set of four cross-coupling resistors Rxp (where "x" is an integer value from 1 to 4) between the LCP pins of the two integrated devices, and has a second set of four cross-coupling resistors Rxn (where "x" is an integer value from 1 to 4) between the LCN pins of the two integrated devices.

[0199] More specifically, Fig. 9 It shows that Figure 4A The inductive angle sensor arrangement 400a or Figure 4B Schematic representation of a circuit 940 for use in 400b, or a variant thereof, the circuit 940 comprising:

[0200] - N inductively coupled transmitter coils (e.g., TX1, TX2, TX3, TX4), together forming an inductively coupled transmitter coil system, N being at least three;

[0201] - a plurality (e.g. also N) of receiver coil groups (not shown), each receiver coil group comprising at least two or at least three receiver coils;

[0202] - the number N of integrated devices (e.g. IC1, IC2, IC3, IC4), each integrated device having a first oscillator pin and a second oscillator pin (IC1: LCP1, LCN1; IC2: LCP2, LCN2; IC3: LCP3, LCN3; IC4: LCP4, LCN4), and each integrated device having an excitation circuit (not explicitly shown) for providing an alternating signal on its oscillator pin, and each integrated device having an evaluation circuit (not explicitly shown) for evaluating signals obtained from a set of receiver coils in the set of receiver coils;

[0203] - at least one movable target (not explicitly shown, but typically only one target, or only two targets) for providing inductive coupling between the inductively coupled transmitter coil system and each set of receiver coils;

[0204] - wherein each transmitter coil (TX1, TX2, TX3, TX4) has a first end (TX1a, TX2a, TX3a, TX4a) operably connected to a first oscillator pin (LCP1, LCP2, LCP3, LCP4) of a first integrated device (IC1, IC2, IC3, IC4), and has a second end (TX1b, TX2b, TX3b, TX4b) operably connected to a second oscillator pin (LCN2, LCN3, LCN4, LCN1) of a subsequent integrated device (IC2, IC3, IC4, IC1).

[0205] In a schematic representation in which the integrated device is located on a virtual circle (e.g., as Fig. 9 ), the term "subsequent integrated device" may mean, for example, "the next IC in the clockwise direction", whereby Fig. 9 In: IC2 is the subsequent integrated device of IC1, IC3 is the subsequent integrated device of IC2, IC4 is the subsequent integrated device of IC3, and IC1 is the subsequent integrated device of IC4. And the term "previous integrated device" may mean, for example, "the next IC in the counterclockwise direction", whereby in Fig. 9 In the figure: IC1 is the previous integrated device of IC2, IC2 is the previous integrated device of IC3, IC3 is the previous integrated device of IC4, and IC4 is the previous integrated device of IC1.

[0206] The inductive angle sensor may further include one or both of the following:

[0207] i) N first resistors (R1p, R2p, R3p, R4p) having a first end connected to a first oscillator pin (LCP1, LCP2, LCP3, LCP4) of a first integrated device (IC1, IC2, IC3, IC4) and having a second end connected to a first oscillator pin (LCP2, LCP3, LCP4, LCP1) of a subsequent integrated device (IC2, IC3, IC4, IC1);

[0208] ii) N second resistors (R1n, R2n, R3n, R4n) having a first end connected to a second oscillator pin (LCN1, LCN2, LCN3, LCN4) of a first integrated device (IC1, IC2, IC3, IC4) and having a second end connected to a second oscillator pin (LCN4, LCN1, LCN2, LCN3) of a previous integrated device (IC4, IC1, IC2, IC3).

[0209] exist Fig. 9 In a variant of , the circuit has only three integrated devices and an equal number of transmitter coils.

[0210] exist Fig. 9 In another variation, the circuit has more than four integrated devices and an equal number of transmitter coils.

[0211] exist Fig. 9 In another or further variation of the present invention, the first set of cross-coupled resistors is omitted, or the second set of cross-coupled resistors is omitted, or both sets of cross-coupled resistors are omitted (e.g., Fig. 6A ).

[0212] exist Fig. 9 In another or further variation of the first and second sets of cross-coupled resistors are omitted, but resistors and / or PCB traces are added to interconnect the center tabs of the transmitter coils to each other.

[0213] Reference numerals:

[0214] 300° Angle Sensor System

[0215] 110,310,410 printed circuit board

[0216] 311 Coil System

[0217] 112,312 movable targets

[0218] 400a, 400b Angle sensor arrangement (including at least: PCB, target, integrated device)

[0219] 320 integrated devices (IC or chip)

[0220] 321 Oscillator Circuit

[0221] 322 Amplifier

[0222] 323 Demodulator or Rectifier and Filter

[0223] 324 Non-volatile memory (e.g., flash memory)

[0224] 325 Controller

[0225] 326 Digital Signal Processor (DSP)

[0226] 327 Analog-to-digital converter (ADC)

[0227] 412a, 412a' first movable target

[0228] 412b,412b' Second movable target

[0229] 441 Torsion bar

[0230] 442 Input shaft section

[0231] 443 Output shaft part

[0232] 444 Axis

[0233] TX Transmitter Coil

[0234] RX1a, RX1b, RX1c first set of receiver coils

[0235] RX2a, RX2b, RX2c second set of receiver coils

[0236] TX1 / TX2 first / second transmitter coil

[0237] TX1a / TX1b The first end / second end of the first transmitting coil

[0238] TX2a / TX2b The first end / second end of the second transmitting coil

[0239] R1, R2, R3 first, second, third resistor

[0240] R1a / R1b The first end / second end of the first resistor

[0241] R2a / R2b The first end / second end of the second resistor

[0242] C1p, C1n, C2p, C2n capacitors

[0243] R1p, R2p, R3p, R4p first group of resistors

[0244] R1n, R2n, R3n, R4n are the second group of resistors

[0245] 540,640,740,840,940 circuits

Claims

1. An inductive angle sensor, comprising: First transmitter coil (TX1); a second transmitter coil (TX2), the second transmitter coil (TX2) being inductively coupled to the first transmitter coil (TX1), the first transmitter coil and the second transmitter coil together forming an inductively coupled transmitter coil system; a first set of receiver coils (RX1a, RX1b, RX1c), the first set of receiver coils comprising at least two or at least three receiver coils; a second set of receiver coils (RX2a, RX2b, RX2c), the second set of receiver coils comprising at least two or at least three receiver coils; a first integrated device (IC1) having a first oscillator pin (LCP1) and a second oscillator pin (LCN1), and having an excitation circuit for providing an alternating signal on the oscillator pins (LCP1, LCN1) of the first integrated device (IC1); and having a plurality of receiver pins connected to the first set of receiver coils (RX1a, RX1b, RX1c); and an evaluation circuit for evaluating signals obtained from the first set of receiver coils; a second integrated device (IC2) having a first oscillator pin (LCP2) and a second oscillator pin (LCN2), and having an excitation circuit for providing an alternating signal on the oscillator pins (LCP2, LCN2) of the second integrated device (IC2); and having a plurality of receiver pins connected to the second set of receiver coils (RX2a, RX2b, RX2c); and an evaluation circuit for evaluating the signals obtained from the second set of receiver coils; at least one movable target (112; 312; 412a, 412a', 412b, 412b') for providing inductive coupling between the inductively coupled transmitter coil system and each set of receiver coils; It is characterized in that The first transmitter coil (TX1) has a first end (TX1a) operably connected to a first oscillator pin (LCP1) of the first integrated device (IC1), and has a second end (TX1b) operably connected to a second oscillator pin (LCN2) of the second integrated device (IC2); and The second transmitter coil (TX2) has a first end (TX2a) operably connected to a first oscillator pin (LCP2) of the second integrated device (IC2), and has a second end (TX2b) operably connected to a second oscillator pin (LCN1) of the first integrated device (IC1).

2. The inductive angle sensor according to claim 1, in, The first integrated device (IC1) is a first packaged semiconductor device having a plurality of pins, and wherein a first oscillator pin (LCP1) and a second oscillator pin (LCN1) of the first integrated device are adjacent pins of the first packaged semiconductor device; And / or wherein the second integrated device (IC2) is a second packaged semiconductor device having a plurality of pins, and wherein the first oscillator pin (LCP2) and the second oscillator pin (LCN2) of the second integrated device are adjacent pins of the second packaged semiconductor device.

3. The inductive angle sensor according to claim 1, Further including: a first capacitor (C1p) having a first end connected to a first oscillator pin (LCP1) of the first integrated device (IC1) and a second end connected to a first reference voltage; and further comprising: a second capacitor (C1n), the second capacitor (C1n) having a first end connected to a second oscillator pin (LCN1) of the first integrated device (IC1), and a second end connected to a second reference voltage; and further comprising: a third capacitor (C2p), the third capacitor (C2p) having a first end connected to the first oscillator pin (LCP2) of the second integrated device (IC2), and a second end connected to a third reference voltage; And further comprising: a fourth capacitor (C2n), the fourth capacitor (C2n) having a first end connected to the second oscillator pin (LCN2) of the second integrated device (IC2), and a second end connected to a fourth reference voltage.

4. The inductive angle sensor according to claim 1, in, The first evaluation circuit is configured for determining a first angle value (α1) based on signals obtained from the first set of receiver coils (RX1a, RX1b, RX1c); And wherein the second evaluation circuit is configured for determining a second angle value (α2) based on signals obtained from the second set of receiver coils (RX2a, RX2b, RX2c).

5. The inductive angle sensor according to claim 1, in, The center position of the first transmitter coil (TX1) is electrically connected to the center position of the second transmitter coil (TX2) via a short circuit or via a resistor.

6. The inductive angle sensor according to claim 1, Further include one or both of the following: a first resistor (R1) having a first end (R1a) connected to a first oscillator pin (LCP1) of the first integrated device (IC1) and having a second end (R1b) connected to a first oscillator pin (LCP2) of the second integrated device (IC2); A second resistor (R2) having a first end (R2a) connected to a second oscillator pin (LCN1) of the first integrated device (IC1) and having a second end (R2b) connected to a second oscillator pin (LCN2) of the second integrated device (IC2).

7. The inductive angle sensor according to claim 1, in, Each of the first and second integrated devices (IC1, IC2) is further configured to detect a loss of oscillation on its first and second oscillator pins.

8. The inductive angle sensor according to claim 1, in, The first and second integrated devices (IC1, IC2) are further configured to determine a frequency value of oscillation on the first and second oscillator pins thereof, and further configured to detect an error based on the frequency value.

9. The inductive angle sensor according to claim 1, comprising a single movable object (112; 312; 412a', 412b'); in, Each of the first and second integrated devices (IC1, IC2) is configured to determine an angular position (α1, α2) of the single movable object.

10. The inductive angle sensor according to claim 9, in, The first integrated device (IC1) is configured to determine a first angle value (α1) of the single movable object; and wherein the second integrated device (IC2) is configured to determine a second angle value (α2) of the single movable object; And wherein the inductive angle sensor is further configured to determine the consistency between the first angle value (α1) and the second angle value (α2).

11. The inductive angle sensor according to claim 1, The invention comprises a first movable target (412a') and a second movable target (412b'), wherein the first movable target (412a') has a first periodicity, and the second movable target (412b') has a second periodicity, and the second periodicity is different from the first periodicity; And among them, the first set of receiver coils having a periodicity equal to the first periodicity, and wherein the second set of receiver coils having a periodicity equal to the second periodicity; and wherein the first integrated device (IC1) is configured to determine a first angular position (α1) of the first movable object relative to the first set of receiver coils; and wherein the second integrated device (IC2) is configured to determine a second angular position (α2) of the second movable object relative to the second set of receiver coils; And wherein the inductive angle sensor is further configured to determine an absolute angular position based on the first angular position (α1) and the second angular position (α2).

12. A torque sensor (400a), comprising: Torsion Bar(441) ； The inductive angle sensor of claim 1, comprising a first movable target (412a) and a second movable target (412b); Wherein, the first movable target (412a) is connected to the torsion bar (441) at a first axial position, and the second movable target (412b) is connected to the torsion bar (441) at a second axial position, and the second axial position is spaced apart from the first axial position.

13. The torque sensor according to claim 12, in, The first integrated device (IC1) is configured to determine a first angular position (α1) of the first movable object relative to the first set of receiver coils (RX1a, RX1b, RX1c); and wherein the second integrated device (IC2) is configured to determine a second angular position (α2) of the second movable object relative to the second set of receiver coils (RX2a, RX2b, RX2c); And wherein the torque sensor is further configured to determine a difference between the first angle value (α1) and the second angle value (α2), and to provide the difference, or a value derived from the difference, as a value indicative of the torque to be measured.

14. An inductive angle sensor, comprising: N inductively coupled transmitter coils (TX1, TX2, TX3, TX4), the N inductively coupled transmitter coils together forming an inductively coupled transmitter coil system, N being at least three; a plurality of sets of receiver coils, each set of receiver coils comprising at least two or at least three receiver coils; N integrated devices (IC1, IC2, IC3, IC4), each having a first oscillator pin and a second oscillator pin (LCP1, LCN1; LCP2, LCN2; LCP3, LCN3; LCP4, LCN4), and each having an excitation circuit for providing an alternating signal on its oscillator pin, and each having an evaluation circuit for evaluating a signal obtained from one of the plurality of sets of receiver coils; at least one movable target (112; 312; 412a, 412b) for providing inductive coupling between the inductively coupled transmitter coil system and the plurality of sets of receiver coils; It is characterized in that Each transmitter coil (TX1, TX2, TX3, TX4) has a first end (TX1a, TX2a, TX3a, TX4a) operably connected to a first oscillator pin (LCP1, LCP2, LCP3, LCP4) of a first integrated device (IC1, IC2, IC3, IC4), and has a second end (TX1b, TX2b, TX3b, TX4b) operably connected to a second oscillator pin (LCN2, LCN3, LCN4, LCN1) of a subsequent integrated device (IC2, IC3, IC4, IC1).

15. The inductive angle sensor according to claim 14, Further include one or both of the following: i) N first resistors (R1p, R2p, R3p, R4p) having a first end connected to a first oscillator pin (LCP1, LCP2, LCP3, LCP4) of the first integrated device (IC1, IC2, IC3, IC4) and having a second end connected to a first oscillator pin (LCP2, LCP3, LCP4, LCP1) of a subsequent integrated device (IC2, IC3, IC4, IC1); ii) N second resistors (R1n, R2n, R3n, R4n), the N second resistors having a first end connected to a second oscillator pin (LCN1, LCN2, LCN3, LCN4) of the first integrated device (IC1, IC2, IC3, IC4) and having a second end connected to a second oscillator pin (LCN4, LCN1, LCN2, LCN3) of a previous integrated device (IC4, IC1, IC2, IC3).

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