Inductive sensor assembly, system, and method

Abstract

An inductive sensor assembly is provided. [Solution] The inductive sensor assembly includes a coil assembly and a movable conductive target. The coil assembly is discontinuously excited by a series of signal pulses. The coil assembly includes three coils arranged in a predetermined configuration and coupled between three terminals. The movable conductive target covers the coils at least partially as it moves. The inductive sensor assembly is configured to measure each current in the coil assembly at predetermined intervals synchronized with the excitation of the coil assembly, thereby determining the displacement of the target.

Description

[Technical Field]

[0001] This disclosure is generally directed towards technologies related to inductive sensors, and more specifically towards technologies related to self-inductance-based inductive sensing. [Background technology]

[0002] Inductive position detection (IPS) is a well-known technique used in a variety of applications to measure the position or proximity of metallic objects. Generally, inductive position sensors employ a non-magnetic technique and utilize physical principles such as eddy currents or inductive coupling to detect the position of a target moving above at least one coil.

[0003] In some conventional implementations, the operation of an inductive sensor is generally based on inductive coupling between a transmitting coil, a target, and at least one receiving coil. For example, Figure 1 shows an example implementation of an inductive-based sensor using one transmitting coil and two receiving coils. Here, the two receiving coils are arranged so that for every 360-degree mechanical rotation of the target, one generates a sine signal and the other generates a cosine signal.

[0004] The coils are typically supplied as copper traces on a printed circuit board (PCB). These coils may be arranged so that a transmitting coil induces a secondary voltage in two receiving coils. This depends on the position of a metal target above the coils. In some embodiments, the transmitting coil may be supplied with an alternating current (AC) signal by an oscillator. This generates a high-frequency magnetic field in the transmitting coil, which is picked up by the receiving coils. Depending on the position of the metal target on the coils, the amplitude and phase of the secondary voltage picked up by the receiving coils may vary. This allows the position of the target to be determined by analyzing these effects.

[0005] However, since the inductance changes depending on how much the target overlaps with the coil, it is also possible to detect the displacement of the target based on only a single coil. The operating principle relies on determining the change in impedance by measuring the current flowing through a single coil, but in practice, a single measurement may be insufficient. This is because this measurement is susceptible to external factors such as temperature and mechanical vibration, which can introduce errors into both the amplitude and offset of the measured current.

[0006] Therefore, there is a need for an improved design for IPS-based sensor implementations that can overcome some or all of the problems associated with the prior art, more specifically, that can objectively determine the position of a target on a coil, and preferably has improved energy efficiency and / or reduced complexity. [Overview of the project]

[0007] In view of some or all of the technical issues described above, the present disclosure generally provides inductive sensor assemblies, systems, and corresponding methods having the features of each independent claim.

[0008] According to one aspect of the present disclosure, an inductive sensor assembly (also referred to herein as a circuit / circuit design, setup, or implementation) is provided. The inductive sensor assembly may include a coil assembly that is discontinuously excited by a series of signal pulses. In particular, the coil assembly may include at least three (or more) coils arranged in a predetermined configuration and coupled between three terminals (or connectors, ends, etc.). For example, in some embodiments, the coils in the coil assembly may be identical. The inductive sensor assembly may further include a movable conductive (e.g., made of copper) target that at least partially covers the coils as it moves. More specifically, the inductive sensor assembly may be configured to measure each current in the coil assembly at a predetermined time synchronized with the excitation at each of the terminals of the coil assembly. This makes it possible to determine the (mechanical) displacement (e.g., (relative) position) of the target. Depending on the various implementations, the predetermined time may be, for example, a predetermined time after the end of the excitation pulse, or a predetermined time during the excitation pulse. Furthermore, as will become apparent from the following description, the proposed inductive sensor assembly may be configured to determine, for example, angular displacement (rotational displacement) or linear displacement (or any other suitable displacement), depending on the various implementations and / or circumstances. The application is not limited thereto. As used herein throughout this disclosure, the term “mechanical displacement” may be used to comprehensively refer to any suitable type of displacement, such as angular displacement, linear displacement, or other more complex trajectories.

[0009] This disclosure, as described herein, aims to propose more energy-efficient and less complex sensor designs that enable the measurement (determination, estimation, etc.) of the displacement (angular or linear) of a target. Furthermore, other advantages not illustrated herein will become apparent from the following description.

[0010] In some exemplary embodiments, the inductive sensor assembly may be configured to determine the angular displacement of a target. In some embodiments, such angular displacement may be a (relative) angular position (e.g., an angle) with respect to a reference angle. As described above, in some other implementations, the inductive sensor assembly may be configured to determine the linear displacement of a target. In such cases, appropriate adaptation of the inductive sensor assembly may be required, as will be understood and recognized by those skilled in the art.

[0011] In some exemplary embodiments, a given arrangement may include a triangular topology or a star topology. In these topologies, each coil is positioned displaced by a predetermined angle in the angular direction with respect to a reference angle (e.g., a reference angle of 0 degrees). Needless to say, other suitable arrangements of the coil assembly are possible, depending on the various mounting configurations and / or circumstances, such as a parallel arrangement. Also, as will be understood and recognized by those skilled in the art, when determining linear position / displacement, each coil may be positioned displaced by a predetermined distance (in the linear direction) with respect to a reference position.

[0012] In some exemplary embodiments, the coil assembly may be sequentially excited at each terminal (to which each coil is coupled), and each current in the coil assembly may be measured continuously at each terminal for a predetermined time after each terminal has been excited. Furthermore, it should be noted that in some cases, as will be described in more detail below, this sequential excitation (drive) / continuous measurement approach may be preferred, for example, from the viewpoint of application-specific integrated circuit (ASIC) design. This is because the internal structure can be simplified by reusing the same excitation driver and sensing circuit for each of the three terminals of the sensor. However, as will be understood and recognized by those skilled in the art, any other suitable implementation is possible, such as simultaneous measurement.

[0013] In some exemplary embodiments, the coil assembly may be excited such that when any one of the three terminals is driven to a first predetermined (e.g., "high") potential, the other two terminals are set to a second predetermined (e.g., "low") potential.

[0014] In some exemplary embodiments, the target has a shape designed such that the inductance of the coil assembly (e.g., equivalent coil inductance) as a function of angular displacement follows a predetermined mathematical function (mathematical formula). As will be understood and recognized by those skilled in the art, in practice, the shape of the target that satisfies a particular function / formula can be derived by various methods such as finite element analysis, electromagnetic field (EM) simulation, etc. The present disclosure is not limited thereto.

[0015] In some exemplary embodiments, each current I of the coil assembly measured at each of the terminals i (i = 1, 2, 3) i , and the corresponding angular displacement φ of the target follow the relationship of the following formula.

[0016]

Equation

[0017] Here, Am represents the modulation amplitude parameter, O represents a static and displacement-independent offset parameter, and φ i represents the predetermined displacement angle of each coil coupled to each of the terminals i with respect to the reference angle.

[0018] In some exemplary embodiments, the angular displacement φ of the target may be determined according to the following formula.

[0019]

Equation

[0020] Here, I irepresents each current of the coil assembly measured at each terminal i (i = 1, 2, 3), and φ i represents the predetermined displacement angle of each coil coupled to each terminal i with respect to the reference angle. Needless to say, as will be understood and recognized by those skilled in the art, a determination similar or analogous to the case of angular displacement can be applied to any other suitable type of displacement, such as, for example, by an equivalent transformation of each coordinate system. For example, for linear displacement, the mathematical expression of this transformation may be as follows.

[0021] [Number]

[0022] Here, ΔX represents the linear displacement, and X R represents the (predetermined) measurement range.

[0023] In some exemplary embodiments, the predetermined time after coil excitation when the current is measured may be determined based on the L-R time constant of the inductive sensor assembly and its drive circuit that generates a series of signal pulses. More specifically, as will be understood and recognized by those skilled in the art, in fact, the "R" element usually has two components, including a component derived from the sensor coil (e.g., the resistance of copper on the PCB) and a component derived from the equivalent resistance of the drive circuit on the ASIC side configured to generate a series of signal pulses for driving / exciting the coil assembly. Usually, the latter is dominant.

[0024] A system is provided according to another aspect of the present disclosure. In particular, the system may include an inductive sensor assembly according to the embodiments described above (and optionally exemplary embodiments). The system may further include a circuit assembly (e.g., an ASIC) coupled to the inductive sensor assembly. More specifically, the circuit assembly may be configured to determine the displacement (e.g., angular or linear displacement) of a target of the inductive sensor assembly by discontinuously exciting a coil assembly of the inductive sensor assembly with a series of signal pulses and measuring the current in the coil assembly at a predetermined time synchronized with the excitation of the coil assembly.

[0025] In some exemplary embodiments, the circuit assembly may be configured to sequentially excite the coil assembly at each of the terminals, and the current in each coil assembly may be measured continuously at each terminal for a predetermined time after each terminal has been excited.

[0026] In some exemplary embodiments, the circuit assembly may be configured to excite the coil assembly such that when one of the three terminals is driven to a first predetermined (e.g., "high") potential, the other two terminals are set to a second predetermined (e.g., "low") potential.

[0027] In some exemplary embodiments, the system may be further configured to support a self-diagnostic function. The self-diagnostic function includes determining the modulation amplitude parameter Am according to the following equation:

[0028]

number

[0029] Furthermore, the self-diagnostic function includes determining a static, displacement-independent offset parameter O according to the following equation.

[0030]

number

[0031] Furthermore, the self-diagnostic function includes determining whether a defect exists in the system based on the determined Am and O and their respective predetermined tolerance limits. In particular, I i φ represents the currents of the coil assembly measured at each terminal i (i=1,2,3), i φ represents the predetermined displacement angle of each coil connected to each terminal i relative to the reference angle, and φ represents the angular displacement of the target. Furthermore, tan(φ), which is used to determine the modulation amplitude parameter Am and the offset parameter O, is calculated according to the following formula.

[0032]

number

[0033] This enables the implementation of continuous health / defect monitoring, i.e., self-diagnostic functionality. Specifically, this can be achieved without additional hardware; only a few additional calculations in the digital domain are required, which provides very high self-diagnostic coverage across the entire signal path. This is extremely important for products where safety is critical.

[0034] Furthermore, according to yet another aspect of the present disclosure, a method is provided for using an inductive sensor assembly. The inductive sensor assembly may be identical or similar to those described above. In particular, the method may include providing a coil assembly in which three coils, arranged in a predetermined configuration and coupled between three terminals, are discontinuously excited by a series of signal pulses. The method may further include providing a movable conductive target that at least partially covers the coils as it moves. This allows for the measurement of each current in the coil assembly at predetermined times synchronized with the excitation at each terminal of the coil assembly, and for determining the displacement of the target.

[0035] Similarly, further embodiments of the present disclosure provide methods for using the system. The system may be identical or similar to those described above. For example, the system may include an inductive sensor assembly comprising a coil assembly in which three (e.g., identical) coils arranged in a predetermined configuration are coupled between three terminals, and a movable conductive target (movable in a rotational or linear direction) that at least partially covers the coils during movement. The system may also include a circuit assembly coupled to the inductive sensor assembly. More specifically, the method may include the circuit assembly discontinuously exciting the coil assembly of the inductive sensor assembly with a series of signal pulses, the circuit assembly measuring each current in the coil assembly at predetermined times synchronized with the excitation at each terminal of the coil assembly, and the circuit assembly determining the displacement (angular or linear displacement) of the target of the inductive sensor assembly based on the measured currents.

[0036] The details of the methods disclosed herein may be implemented as a system (e.g., in the form of a circuit, circuit assembly, etc.) adapted to perform some or all of the steps of the method, as will be recognized by those skilled in the art, and vice versa. In particular, the methods disclosed herein relate to methods for operating systems (or circuits) according to the embodiments and variations thereof described above, and it should be noted that each description relating to a system (or circuit) applies equally to the corresponding method, and vice versa.

[0037] Furthermore, please note that in this disclosure, the term "bonding" refers to a state in which elements are electrically able to communicate with each other, whether directly connected via, for example, a wire, or in other forms (e.g., indirectly). An example of "bonding" is "connection." [Brief explanation of the drawing]

[0038] Exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings, where identical or similar elements are denoted by the same reference numerals. [Figure 1] This diagram schematically illustrates an example of a conventional induction-based sensor implementation. [Figure 2] This diagram schematically illustrates an example of the functional relationship between target displacement and coil inductance, achieved by appropriately designing the target's shape. [Figure 3] This figure schematically illustrates an example of the relationship between current and target angular displacement when a coil assembly is excited by a pulse signal, as described in some embodiments of the present disclosure. [Figure 4] This figure schematically shows an example of the arrangement of coils in an inductive sensor assembly according to some embodiments of the present disclosure. [Figure 5A] This figure schematically shows an example of coil arrangement according to some embodiments of the present disclosure. [Figure 5B] This figure schematically shows an example of coil arrangement according to some embodiments of the present disclosure. [Figure 6A] This figure schematically illustrates some implementation examples of coil excitation methods according to several embodiments of the present disclosure. [Figure 6B] This figure schematically illustrates some implementation examples of coil excitation methods according to several embodiments of the present disclosure. [Figure 7] This figure schematically illustrates an example of a system, according to some embodiments of the present disclosure, that includes an inductive sensor assembly and an application-specific integrated circuit (ASIC) for use with the inductive sensor assembly. [Figure 8] This figure schematically illustrates an example of an implementation for determining the linear displacement of a target by equivalent transformation of each coordinate system, according to several embodiments of the present disclosure. [Figure 9] This figure schematically illustrates another example of an implementation for determining the linear displacement of a target, according to some embodiments of the present disclosure. [Figure 10]This flowchart schematically illustrates an example of a method using an inductive sensor assembly according to some embodiments of the present disclosure. [Figure 11] This flowchart schematically illustrates an example of how to use the system according to some embodiments of the present disclosure. [Modes for carrying out the invention]

[0039] As stated above, unless otherwise specified, the same or similar reference numerals described herein may refer to the same or similar elements. Therefore, for the sake of brevity, repeated descriptions of them may be omitted. Furthermore, unless otherwise specified, it should be noted that the reference numerals used in the drawings are for illustrative purposes only and should not be understood as constituting any kind of limitation.

[0040] As stated above, in a broad sense, this disclosure relates to the technical field of inductive sensors (also known as induction-based sensors), and more specifically, to the technology relating to self-inductance-based inductive sensing.

[0041] Furthermore, as mentioned above, a typical conventional sensor implementation (for example, as illustrated in Figure 1) can generally be configured to perform positioning based on a variable mutual inductance between a transmitting coil and a receiving coil.

[0042] In contrast, in a broader sense, the technology proposed in this disclosure is implemented based on the self-inductance of a sensor coil and the dependence of that self-inductance on the position of a target. In some cases, the inductance changes depending on how much the target overlaps with the coil, so it may also be possible to detect the displacement of the target based on only a single coil.

[0043] However, as mentioned above, the operating principle relies on determining changes in the impedance of a coil by measuring the current flowing through a single coil, but in practice, a single measurement is often insufficient. This is mainly because the measurement is susceptible to external factors such as temperature and mechanical vibration, which can introduce errors into both the (modulation) amplitude (also called the dynamic range of the signal) and the static, displacement-independent offset (also called the DC offset) of the measured current.

[0044] In view of the foregoing, one of the primary technical objectives of the Disclosure, in a broad sense, is to find an improved design for an IPS-based sensor implementation that can solve some or all of the problems relating to the prior art, more specifically, to enable objective determination of the position of a target on a coil, preferably with improved energy efficiency and / or reduced complexity. To achieve this, in a broad sense (but not limited to), the Disclosure proposes providing three (e.g., identical) coils (or collectively referred to as a coil assembly) connected / coupled at a predetermined and known angular offset, arranged to supply voltage pulses to the coils, and sampling the current at a predetermined time after a (non-periodic) charge / discharge process has started.

[0045] In general, pulse-based drive systems are considered to offer several advantages, including (but are not limited to) simplification of coil drive circuits, reduction of spectral density and average level of radiated electromagnetic (EM) interference, improved energy efficiency, and easy adaptation to a wide range of inductive sensors and specific application requirements (e.g., speed, current consumption, EMC, etc.) by controlling pulse width and period. Needless to say, other applicable implementations, purposes, and / or advantages of this disclosure will become apparent from the detailed description below.

[0046] Many of the examples described below may refer to, or may seem to focus on, examples of implementations for determining the angular displacement of a target (capable of moving in a rotational or angular direction), but as will be understood and recognized by those skilled in the art, the techniques proposed herein are also suitably applicable for determining the linear displacement (or any other suitable mechanical displacement) of a target capable of moving in a linear direction. In any case, for the sake of illustration, some implementation examples for suitably determining the linear displacement of a target will also be described in more detail below.

[0047] First, the sensor part will be described.

[0048] Specifically, when a conductive (e.g., copper) plate, also called the target, covers a part (S o ) of the entire cross-section (S c ) of the coil, due to the eddy currents induced on the plate and the accompanying influence on the magnetic field passing through the coil, the equivalent inductance (L e ) of the coil can become a part of the original inductance (L o ). In some examples, the equivalent inductance may be reduced according to the following formula / Equation (1).

[0049]

Number

[0050] Therefore, by appropriately designing the shape of the target, the relationship between the (mechanical) displacement (e.g., Δφ as an angular displacement or Δx as a linear displacement) and the inductance of the coil can be an arbitrary mathematical function differentiable within the measurement range (e.g.,

[0051]

Number

[0052] It may be appropriately formed to follow the function represented by (see, for example, the diagram illustrated in Figure 2). Thus, equation (1) above can be expressed as follows:

[0053]

number

[0054] As described above, by appropriately designing the shape of the target, the modulation function of the sensor can be controlled according to the requirements of the system. In this specification, a target whose shape is appropriately designed with respect to angle measurement (and similarly with respect to linear measurement) is defined as L in any appropriate mathematical expression such as the following equation. e It may be any target such that it is represented.

[0055]

number

[0056] In particular, the parameter K may be considered to define the sampling time relative to the LR time constant of the coil. That is, it is given by the following equation:

[0057]

number

[0058] In some cases, the sampling time is,

[0059]

number

[0060] This may be, but is not limited to, the maximum sensitivity. Generally, a predetermined time T0 after coil excitation, at which current is measured, may be determined based on the LR time constant of the inductive sensor assembly and its drive circuit that generates a series of signal pulses. In particular, the "R" element generally has two components: one is a component originating from the sensor coil (e.g., the resistance of copper on the PCB), and the other is the equivalent resistance of the drive circuit in the ASIC, which is usually dominant.

[0061] Furthermore, the parameter M is the equivalent inductance L, which is determined by the modulation index selected for the sensor, i.e., the target displacement φ. e It can also be considered as indicating the extent to which (φ) changes.

[0062]

number

[0063] (or simply

[0064]

number

[0065] (That is.)

[0066] As those skilled in the art will understand and recognize, in practice, L follows formula (3) above. e The target shape from which the result can be generated may be derived by any suitable method, such as finite element analysis or EM simulation, depending on the various implementation forms and / or circumstances.

[0067] When using a single coil, it has been shown that the current flowing through the coil may depend on the displacement of the target on the coil. For an angular displacement φ, the current at a given sampling time T0 may be given by the following equation.

[0068]

number

[0069] Here, L e (φ) represents the equivalent inductance of the coil with respect to the displacement φ, and R represents the resistance connected in series with the coil.

[0070] Therefore, in some implementations, when a rectangular voltage pulse is supplied to the coil, it is theoretically possible to determine the (relative) position of the target by measuring the current after T0 (for example, after the end of the excitation pulse or during the excitation pulse).

[0071] In some implementations, for example, for a sensor configured to measure angular displacement, substituting equation (3) into the above general equation (4) can further simplify it to the following equation.

[0072]

number

[0073] Here, the parameter Am generally represents the amplitude of the signal (modulation) (generally corresponding to the dynamic range illustrated in Figure 3). The parameter O is generally static and represents the displacement-independent offset (roughly corresponding to the DC offset illustrated in Figure 3).

[0074] If both parameters Am and O are known, then the current I T0 A single measurement of (φ) is sufficient to calculate the position φ. However, as mentioned above, it may be affected by various external factors such as temperature, mechanical vibration, and changes in the air gap, and both parameters Am and O may not be known.

[0075] In other words, theoretically, a sensor with a single coil can determine that a target has moved and derive how much it has rotated, but such a sensor configuration would result in very low accuracy and repeatability.

[0076] Therefore, in order to solve this problem and objectively determine the actual angular position of the target, it may be necessary to be able to determine all the unknowns in equation (5) above, namely all the parameters Am, φ, and O. For this purpose, in a broad sense, it is necessary to obtain two more data points and solve the following equation for the angular displacement φ.

[0077]

number

[0078] Here, it should be noted that A, B, and C are merely for the sake of clarity. As those skilled in the art will understand and recognize, these essentially correspond to the measurable currents according to equation (5) above. Thus, I, where i = 1, 2, and 3 respectively, i It can be easily replaced with this.

[0079] In some examples, a simple approach to implementing this is to add two additional measuring probes (coils) to the sensor assembly and position them displaced by a fixed (e.g., predetermined) angle (φ2 and φ3) relative to a reference angle of 0 degrees. Figure 4 shows an example where three currents with three different phases are obtained due to an example of angular displacement of the target. As mentioned above, these three coils are sometimes collectively referred to as a coil assembly. Note that in the example in Figure 4, the coils appear to be evenly displaced (120 degrees) within the circle, but this is not always the case. For example, in some examples, only a part / part of the entire measuring range (corresponding to the entire circle) may be important for a particular application. In this case, the coils may be positioned appropriately accordingly, for example, at different angular positions within the circle.

[0080] In this way, by solving equation (6) for φ, it can be shown that the angular displacement φ can be mathematically determined.

[0081]

number

[0082] As described above, A, B, and C are generally used to represent the three currents measured at the three corresponding pins / terminals A, B, and C shown in Figures 5A and 5B, and φ1, φ2, and φ3 are (predetermined) constants defined by the proper arrangement of the three coils in the sensor assembly, as described above.

[0083] It should be noted that in some implementations, calculating the angle φ based on equation (7) above may be based on subtracting the (current) values ​​of A, B, and C. This can be easily implemented in the analog domain. In particular, this makes it possible to eliminate the common DC offset and to use the full range of the analog-to-digital converter (ADC) in the signal path, as will be explained in more detail below with respect to ASIC design.

[0084] Depending on the various implementation configurations and / or requirements, the coil may be configured in any suitable arrangement. For example, in some implementation configurations, the coil may be configured in a triangular topology (Figure 5A) or a star topology (Figure 5B). In this case, measurements at each pin / terminal may be performed continuously.

[0085] In some examples, a star topology can be transformed into a parallel topology, for example, when the center of the star is coupled to a predetermined reference potential / node (e.g., ground). In this case, it may also be possible to measure the currents at pins A, B, and C simultaneously. That is, the sensor coils can be excited / measured simultaneously using dedicated drive / sensor circuits for each channel, while all other considerations can be maintained in the same way. This configuration may be considered applicable in some specific cases, such as when high accuracy is required by the application for fast-moving targets.

[0086] On the other hand, although it is theoretically possible to measure the currents at A, B, and C in parallel (by grounding the center of the star topology in Figure 5B as described above), this particular arrangement may be considered undesirable in some other cases compared to measuring the currents at A, B, and C continuously using the star or triangular topology as described above. One of the main reasons for this is that simultaneously exciting and measuring the currents at A, B, and C may potentially require the implementation of three identical drive / sensor circuits operating in parallel. In contrast, the continuous measurement method generally requires only a single ASIC, which results in reductions in size, cost, and complexity in particular.

[0087] To measure the current at terminals A, B, and C, any suitable method can be used depending on the various implementation configurations and / or circumstances. For example, in the case of a triangular topology / arrangement, the following excitation sequence may be used to generate current in the coil, as illustrated in Figure 6A.

[0088] In particular, the coil may be sequentially excited / driven at terminals A, B, and C by each pulse (indicated as "charge") shown in Figure 6A. This allows for continuous measurement of the current in the coil at a predetermined time T0 after each terminal is excited. Specifically, as illustrated in Figure 6A, the coil may be excited such that when one of the three terminals A, B, and C is driven to a first predetermined potential (e.g., "high"), the other two terminals are set to a second predetermined potential (e.g., "low"). In other words, simply put, there are no floating nodes / terminals / pins at any point during the excitation of the coil.

[0089] The excitation / drive sequence described above can also function in a star topology, as will be understood and recognized by those skilled in the art.

[0090] For completeness, it should be noted that in some other examples, different excitation / driving methods may be used in star topology, as illustrated in Figure 6B. Needless to say, as will be understood and recognized by those skilled in the art, such excitation / driving methods are also appropriately applicable to triangular topology (or any other suitable topology).

[0091] In particular, as shown in Figure 6B, one of the A, B, and C pins is always in a floating state (indicated as "Z_state"). Nevertheless, in some cases, leaving one of A, B, and C in a floating state after current has flowed can generate undesirable electromagnetic field (EMF) spikes. Therefore, in a preferred embodiment, as described above, the node should not be left in a floating state at any point. In other words, in any topology selected, in a preferred embodiment, terminals A, B, and C are driven such that one of A, B, and C is "high" (or any other suitable reference potential) and the other two are "low" (or any other suitable reference potential).

[0092] The above-described driving method may be considered to result in measuring the two sensor coils simultaneously. That is, in such a configuration, the equivalent inductance L of the entire coil assembly, rather than for a single coil, is measured. e This is one reason why equation (3) above should be applied to the above. In some cases, this may make the system more sensitive to asymmetry in the three drive channels. However, it should be noted that the proposed technique is preferable from the standpoint of practical implementation, as will be understood and recognized by those skilled in the art.

[0093] Next, we will describe the ASIC side. In particular, Figure 7 shows an example (of course not limited to) of an exemplary implementation of the topology of the ASIC720 used with the sensor 710 described above. Generally, the ASIC720 supplies a voltage pulse (such as a rectangular waveform) to one of A, B, and C and measures the sample for a predetermined time after the charging / discharging process of the coil has started. In this way, the ASIC720, especially when used in combination with the sensor 710 described above, enables the information necessary to solve equation (7) above to be passed into the digital domain, and at the same time, enables the maximum utilization of the dynamic range of the ADC725, as described above.

[0094] In particular, the driver stage 721 may be configured to apply the excitation / driving and measurement methods described above to the three ends (A, B, and C) of the coil. While conventional sensor implementations (e.g., those shown in Figure 1) typically drive the coil with AC current from an oscillator, in this disclosure, the ASIC may supply pulses (e.g., square wave, rectangular wave) to the coil assembly to excite the coil discontinuously. As those skilled in the art will understand and recognize, exciting the transmitting coil with short (discontinuous) pulses may have at least the following effects: First, glitchy excitation signals (e.g., short rectangular pulses) generally have a wide spectral bandwidth, allowing their energy to be distributed over a wider frequency band. This reduces the spectral density of electromagnetic noise generated by the system during operation, improving EMC performance. Furthermore, compared to conventional AC current-based technologies, the need to continuously supply current to the coil is eliminated, significantly reducing the sensor's power consumption. Therefore, the ASIC may also be powered synchronously with a series of pulses. Furthermore, since the current supplied to the coil and the induced current are already in a form suitable for subsequent processing, a rectifier is not required. The design of the excitation generator can also be significantly simplified. In some examples, the clock scheme for pulse generation may be randomized (for example, by using an analog random number generator). This significantly reduces the electromagnetic interference that the coil may exert on neighboring circuits. Additionally, using a randomized clock scheme can break correlation with external interference signals, for example. This has a desirable effect in improving the system's immunity to electromagnetic interference.

[0095] Furthermore, the current sensing stage 722 and the sample-and-hold stage 723 enable sampling of the current at all three phases of the measurement, and with the help of the MUX stage 724, it is possible to selectively subtract the currents at A, B, and C.

[0096] As a result, the calculation of (BA), (AC), and (CB) for equation (7) above can be considered to be possible in the analog domain. This cancels out the DC offset of the signal, allowing the dynamic component of the information signal to make full use of the ADC's dynamic range. The rest of the system / circuit follows a known receive path topology, so for the sake of brevity, a detailed explanation is omitted here.

[0097] Needless to say, as those skilled in the art will understand and recognize, this exemplary implementation of the ASIC720 shown in Figure 7 is provided for illustrative purposes only and should not be understood to constitute any kind of limitation. Depending on the circumstances and / or requirements, any other suitable implementation of the ASIC may be adopted.

[0098] It should be noted that the proposed ASIC architecture, especially when used in combination with the proposed sensor assembly, may also be considered to enable the following advantages in general: namely, the following: The differential signal paths proposed herein may be considered to be resistant to common-mode and power supply interference. • Because information is carried by the flow of current rather than voltage potential, it is less susceptible to the effects of voltage drop (e.g., I*R drop) and parasitic coupling. • In the case of a star topology, the equivalent inductance L e (φ) is always greater than the inductance of the individual coils. In this case, a higher inductance may be considered preferable in terms of sensor sensitivity and the electrical requirements of the ASIC. This contributes to miniaturization of the sensor. The current from the sensor may be sampled and subtracted in the analog domain. This cancels out the DC offset of the signal in the preceding stage. As a result, the dynamic component of the information signal allows for maximum utilization of the ADC's dynamic range. Finally, complex signal post-processing can be moved entirely into the digital realm.

[0099] Furthermore, it should be noted that the entire system (i.e., the combination of sensors and ASICs mentioned above) may be considered to offer further advantages through continuous health / defect monitoring.

[0100] More specifically, if the sensor malfunctions, the derived values ​​of parameters Am and O may be used to determine whether or not an error exists. Similar to equation (7) above, the other two unknowns, namely the amplitude parameter Am and the offset parameter O, may be determined from equation (6) using equations (8) and (9) below, respectively.

[0101]

number

[0102]

number

[0103] It should be noted that in equations (8) and (9) above, the tan(φ) used to determine the amplitude parameter Am and the offset parameter O may be calculated according to the following equation based on equation (7).

[0104]

number

[0105] If a defect or malfunction occurs, the values ​​of these two parameters may exceed narrow tolerance limits (defined, for example, by natural but relatively small process, voltage, and temperature (PVT) fluctuations), which may trigger appropriate alarm signals or the like.

[0106] Furthermore, the self-diagnostic function described above generally does not require additional hardware. While only additional calculations in the digital domain are necessary to provide this benefit, it can offer extremely high self-diagnostic coverage across the entire signal path, which may be considered a critical requirement for safety-critical products.

[0107] Furthermore, it should be noted that in some cases, the system can be easily and inexpensively calibrated for potential asymmetry between channels. Such asymmetry can manifest as angular errors and nonlinearity. In particular, by performing measurements at only three data points (target positions) during production testing after the system has been manufactured, individual φ for each channel (A, B, and C) can be measured. i This also makes it possible to determine the amplitude. These are further stored in the ASIC as normalized data, which can then be used to calibrate the sensor as needed.

[0108] Furthermore, while many of the examples described above may appear to focus on determining the angular displacement of targets that are movable (rotationally or angularly), the techniques proposed herein can also be applied (e.g., with appropriate adaptation) to determining the linear displacement of targets that are movable in a linear direction. For completeness, several possible (but not limited to) examples illustrating the general principles for determining linear displacement are described below with reference to the drawings.

[0109] The first implementation shown in Figure 8 may be considered relatively straightforward. That is, this implementation generally illustrates the possible transformations between the polar coordinate system used for determining angular displacement and the Cartesian coordinate system that can be used for determining linear displacement, as well as how the coil arrangement and target shape may change when determining linear displacement.

[0110] A unique feature of this simplified sensor configuration is that the coil PCB can be made relatively small. However, as illustrated in Figure 8, in this example the target length can be twice the measurement range, which may be considered unsuitable for some potential applications.

[0111] As a second possible implementation for determining linear displacement, Figure 9 schematically shows a linear position sensor having a parallel arrangement (topology) of coils. This may allow for a smaller target size and a simpler shape. This may, in turn, be considered a preferred embodiment for many industrial applications. In a broad sense, as will be understood and recognized by those skilled in the art, in this particular example, the required mathematical relationship / function between the target position and the self-inductance of the coil may be achieved by appropriately designing the shape of the coil winding.

[0112] Finally, Figures 10 and 11 schematically show flowcharts illustrating examples of methods according to some exemplary embodiments of the present disclosure.

[0113] In particular, Figure 10 schematically shows an example of Method 1000 using an inductive sensor assembly according to some embodiments of the present disclosure. The inductive sensor assembly may be one of those described above with reference to the drawings or similar. In particular, Method 1000 may include, in step S1010, providing a coil assembly in which three coils, which are discontinuously excited by a series of signal pulses and arranged in a predetermined configuration, are coupled between three terminals. Method 1000 may further include, in step S1020, providing a movable conductive target that at least partially covers the coils as it moves. This allows for the measurement of each current in the coil assembly at a predetermined time synchronized with the excitation at each terminal of the coil assembly, and for determining the displacement of the target.

[0114] Similarly, Figure 11 schematically shows an example of Method 1100 using a system according to several embodiments of the present disclosure. The system may be identical or similar to those described above with reference to the drawings, etc. For example, the system may include an inductive sensor assembly comprising a coil assembly in which three (e.g., identical) coils arranged in a predetermined configuration are coupled between three terminals, and a movable conductive target (movable in a rotational or linear direction) that at least partially covers the coils during movement. The system may also include a circuit assembly coupled to the inductive sensor assembly. More specifically, Method 1100 may include, in step S1110, the circuit assembly discontinuously exciting the coil assembly of the inductive sensor assembly with a series of signal pulses. Method 1100 may further include, in step S1120, the circuit assembly measuring each current in the coil assembly at predetermined time points synchronized with the excitation at each terminal of the coil assembly. Finally, in step S1130, the method 1100 may also include the circuit assembly determining the displacement (angular or linear displacement) of the target of the inductive sensor assembly based on the measured current.

[0115] The technology proposed in this disclosure offers several advantages, including, but not limited to, high configurability (generally meaning that a single product can be configured to serve many applications), relatively easy implementation due to the absence of a demanding analog section, availability of readily usable and high-coverage self-diagnostic methods for the entire signal path, ability to meet higher automotive safety integrity levels (ASIL), high EMC robustness, low current consumption, low cost of goods sold (COGS), and minimization of the bill of materials (BOM) for external components.

[0116] It should be noted that exemplary mounting configurations using coils that appear to have a specific winding shape, arrangement, or installation as shown in the drawings are provided for illustrative purposes only and should not be understood as limitations of any kind. Any other suitable arrangement, mounting configuration, and / or application configuration may be adopted, as will be understood and recognized by those skilled in the art.

[0117] Furthermore, it should be noted that the characteristics of the circuits / systems described above, while not explicitly stated for the sake of brevity, correspond to the characteristics of the corresponding methods. The disclosures herein are considered to extend to the characteristics of such methods as well. In particular, it should be noted that these disclosures relate to methods for manufacturing and / or operating the circuits / systems described above, and / or methods for providing and / or arranging the elements of the circuits / systems.

[0118] Furthermore, it should be noted that the examples of embodiments of this disclosure are applicable to a variety of applications or system configurations, depending on the underlying technical field. In other words, the examples shown in the drawings above and used as the basis for the examples described above are merely illustrative and do not limit this disclosure in any way. That is, based on the defined principles, additional existing and proposed novel functionalities available in the corresponding operating environments can be used in connection with the examples of embodiments of this disclosure.

[0119] Finally, it should be noted that the descriptions and drawings herein are merely illustrative of the principles of the proposed circuits and methods. Those skilled in the art will be able to embody the principles of the present invention and implement various configurations that fall within its spirit and scope, even if not expressly described or illustrated herein. Furthermore, all examples and embodiments outlined herein are expressly intended solely for illustrative purposes to help the reader understand the principles of the proposed methods. Moreover, all descriptions herein that provide the principles, aspects and embodiments of the present invention, as well as specific examples thereof, are intended to encompass their equivalents.

Claims

1. An inductive sensor assembly, A coil assembly in which three coils arranged in a predetermined configuration are coupled between three terminals and are discontinuously excited by a series of signal pulses, A movable conductive target that covers the coil at least partially during movement, Includes, An inductive sensor assembly configured to determine the displacement of the target by measuring the current in each of the coil assembly at a predetermined time synchronized with the excitation at each of the terminals of the coil assembly.

2. The induction sensor assembly according to claim 1, configured to determine the angular displacement of the target.

3. The induction sensor assembly according to claim 2, wherein the predetermined arrangement includes a triangular topology or a star topology, and in the topology, the coils are arranged to be displaced in the angular direction by a predetermined angle with respect to a reference angle.

4. The inductive sensor assembly according to claim 2, wherein the coil assembly is sequentially excited at each of the terminals, and the current of each of the coil assembly is continuously measured at each of the terminals for a predetermined time after each of the terminals has been excited.

5. The inductive sensor assembly according to claim 2, wherein the coil assembly is excited such that when one of the three terminals is driven to a first predetermined potential, the other two terminals are set to a second predetermined potential.

6. The inductive sensor assembly according to claim 2, wherein the target has a shape designed such that the inductance of the coil assembly as a function of the angular displacement follows a predetermined mathematical function.

7. Each current I of the coil assembly is measured at each of the terminals i (i = 1, 2, 3). ｉ , and the corresponding angular displacement of the target is given by the following equation [Number 22] This follows the relationship where Am represents the modulation amplitude parameter, O represents a static, displacement-independent offset parameter, and φ ｉ The induction sensor assembly according to claim 2, wherein represents a predetermined displacement angle of each of the coils coupled to each of the terminals i with respect to a reference angle.

8. The angular displacement φ of the target is given by the following equation [Number 23] It is determined according to the following, where I ｉ φ represents the currents of the coil assembly measured at each of the terminals i (i = 1, 2, 3), ｉ The induction sensor assembly according to claim 2, wherein represents a predetermined displacement angle of each of the coils coupled to the terminal i with respect to a reference angle.

9. The inductive sensor assembly according to claim 2, wherein the predetermined time after excitation of the coil on which the current is measured is determined based on the L-R time constant of the inductive sensor assembly and its drive circuit that generates the series of signal pulses.

10. A system comprising an inductive sensor assembly and a circuit assembly as described in claim 1, The circuit assembly is configured to determine the displacement of the target of the inductive sensor assembly by discontinuously exciting the coil assembly of the inductive sensor assembly with a series of signal pulses and by measuring the current of the coil assembly at a predetermined time synchronized with the excitation of the coil assembly. system.

11. The system according to claim 10, wherein the circuit assembly is configured to sequentially excite the coil assembly at each of the terminals, and the current of each coil assembly is continuously measured at each of the terminals for a predetermined time after each of the terminals has been excited.

12. The system according to claim 10, wherein the circuit assembly is configured to excite the coil assembly such that when one of the three terminals is driven to a first predetermined potential, the other two terminals are set to a second predetermined potential.

13. The system is further configured to support a self-diagnostic function, The self-diagnostic function described above is: The following formula [Number 24] The modulation amplitude parameter Am is determined accordingly, The following formula [Number 25] The static, displacement-independent offset parameter O is determined accordingly, This includes determining whether a defect exists in the system based on the determined Am and O and their respective predetermined tolerance limits, Here, I ｉ φ represents the currents of the coil assembly measured at each of the terminals i (i = 1, 2, 3), ｉ φ represents the predetermined displacement angle of each of the coils connected to each of the terminals i with respect to the reference angle, and φ represents the angular displacement of the target. The tan(φ) used to determine the modulation amplitude parameter Am and the offset parameter O is given by the following equation [Number 26] Calculated according to, The system according to claim 10.

14. A method using an inductive sensor assembly, To provide a coil assembly in which three coils, which are discontinuously excited by a series of signal pulses and arranged in a predetermined configuration, are coupled between three terminals, To provide a movable conductive target that covers the coil at least partially while it is in motion, Includes, This allows the current in each of the coil assembly to be measured at a predetermined time synchronized with the excitation at each of the terminals of the coil assembly, thereby determining the displacement of the target. method.

15. A method of using the system, The aforementioned system, An inductive sensor assembly comprising a coil assembly in which three coils arranged in a predetermined configuration are coupled between three terminals, and a movable conductive target that at least partially covers the coils during movement, A circuit assembly coupled to the aforementioned inductive sensor assembly, Includes, The circuit assembly causes the coil assembly of the inductive sensor assembly to be discontinuously excited by a series of signal pulses, The circuit assembly measures the current in each of the coil assembly at a predetermined time synchronized with the excitation at each of the terminals of the coil assembly, The circuit assembly determines the displacement of the target of the inductive sensor assembly based on the measured current, Methods that include...

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