Sensor device and system with non-linear compensation

Abstract

A sensor circuit (620) for measuring physical quantities, comprising: a signal acquisition circuit (640) including sensors (621, 622) for providing input signals (v1, v2) related to the physical quantity; and a processing circuit (650) for receiving the input signals (v1, v2) and providing an output signal (θ) representing the physical quantity. 校正 The processing circuitry includes a closed loop comprising: a first sub-circuit (660) arranged to receive the input signals (v1, v2) and feedback signals (fbi, fbq), and configured to provide a first signal (θ). 估计 ); a frequency correlation filter (632) for receiving and filtering the first signal (θ) 估计 ), and is used to provide the output signal (θ) 校正 ); a second sub-circuit (670), which is used to receive the filtered signal (θ) 校正 ) and use a nonlinear function to filter the signal (θ) 校正 ) are converted into the feedback signals (fbi, fbq).

Description

Technical Field

[0001] This invention generally relates to the field of sensor systems and devices, such as magnetic sensor systems and devices, magnetic position sensor systems and devices, and linear or angular position sensor systems and devices. Background Technology

[0002] Various sensor systems are known in the art. They typically include one or more sensors or transducers for measuring the characteristics of physical quantities (e.g., current, temperature, mechanical pressure, mechanical force, mechanical torque, linear position, angular position, etc.), and circuitry for converting the measured signals into electrical signals (e.g., current or voltage), as well as circuitry for processing the electrical signals.

[0003] As examples, US2020191834 (A1) describes a sensor device including one or more magnetic sensors for measuring a magnetic field indicating the magnitude of a current. WO2015086680 (A1) describes a pressure sensor that uses a piezoresistive sensor element to measure resistance indicating mechanical pressure applied to a membrane. EP3851820 (A1) describes a sensor structure for measuring mechanical torque using a magnetic sensor. EP3865825 (A1) describes a sensing angular position sensor including multiple receiver coils for measuring a signal indicating the angular position of a target. EP3650816 (A1) describes a linear and angular position sensor system that measures a magnetic field and determines position based on the ratio of magnetic field components or the ratio of magnetic field gradients.

[0004] In many such systems, the physical quantity to be measured (e.g., current, angular position, mechanical torque, etc.) is not measured directly, but indirectly by measuring another signal (e.g., a magnetic field component) that is related to the physical quantity. Ideally, the measured signal is proportional to the physical quantity (i.e., zero offset and a constant scaling factor), but in practice this is usually not the case, and the measured signal has a nonlinear relationship with the quantity to be measured.

[0005] Many variations of sensor systems exist, addressing one or more of the following requirements: using simple or inexpensive sensor structures; using simple or inexpensive sensor circuitry or devices; being able to measure over a relatively large range; being able to measure with high accuracy; requiring only simple arithmetic; being able to measure at high speed; being highly robust to positioning errors; being highly robust to external interference fields; providing redundancy; being able to detect errors; being able to detect and correct errors; having a good signal-to-noise ratio (SNR); having good linearity, etc. Often, two or more of these requirements conflict with each other, thus requiring trade-offs.

[0006] There is always room for improvement or replacement. Summary of the Invention

[0007] The purpose of embodiments of the present invention is to provide a sensor circuit for measuring a physical quantity and for providing an output signal associated with that physical quantity.

[0008] The purpose of embodiments of the present invention is to provide a sensor circuit configured to reduce the error between the output signal and the physical quantity to be measured.

[0009] The purpose of embodiments of the present invention is to provide a sensor circuit configured to improve the linearity between an output signal and a physical quantity to be measured.

[0010] The object of certain embodiments of the present invention is to provide an integrated semiconductor device including such sensor circuitry, for example, a packaged device including a semiconductor substrate implemented in a CMOS process.

[0011] The purpose of specific embodiments of the present invention is to provide position sensor circuits, position sensor devices, and position sensor systems with good or improved linearity.

[0012] The object of a particular embodiment of the present invention is to provide an angular position sensor system having improved angular velocity linearity, the angular velocity spanning at least a range of 1 krpm to 5 krpm, or 1 krpm to 25 krpm, or 1 krpm to 100 krpm, or 1 krpm to 200 krpm.

[0013] The purpose of embodiments of the present invention is to provide an integrated sensor device (e.g., a packaged device including at least one semiconductor die (also referred to as a “chip”)) capable of measuring physical quantities related to magnetic fields (e.g., linear position, angular position, current amplitude, proximity indication, etc.).

[0014] The purpose of this invention is to provide an integrated sensor device including a semiconductor substrate, wherein physical quantities (e.g., linear position, angular position, current amplitude, proximity indication, acceleration, radiation intensity, visible light intensity, IR light intensity, pressure, etc.) are measured with improved accuracy (e.g., improved linearity over its measurement range).

[0015] The purpose of embodiments of the present invention is to provide such magnetic sensor systems, circuits or devices suitable for use in industrial, robotic or automotive environments.

[0016] These objectives are achieved through embodiments of the present invention.

[0017] According to a first aspect, the present invention provides a sensor circuit for measuring a physical quantity, the sensor circuit comprising: a signal acquisition circuit including at least one sensor (e.g., a coil, a sensor element) configured to provide at least one input signal (e.g., v1, v2) relating to (or associated with) a physical quantity, or indicating a characteristic of the physical quantity; and a processing circuit configured to receive the at least one input signal (e.g., v1, v2) and to provide an output signal (e.g., θ) representing the physical quantity. 校正 The processing circuitry includes a closed loop comprising: i) a first sub-circuit arranged to receive the at least one input signal (e.g., v1, v2) and at least one feedback signal (e.g., fbi, fbq); θ fb1 ;θ fb2 ), and includes a combiner configured to provide a first signal (e.g., θ). 估计 θ 计算 ); ii) a frequency correlation filter configured to receive and filter the first signal (e.g., θ). 估计 θ 计算 ), and is used to provide the filtered signal or the signal derived therefrom as the output signal (e.g., θ). 校正 ); and iii) a second sub-circuit configured to receive the filtered signal (e.g., θ). 校正 ), and is used to filter the signal (e.g., θ) using a nonlinear function. 校正 ) is converted into at least one feedback signal (e.g., fbi, fbq; θ) fb1 ;θ fb2 ).

[0018] Preferably, a nonlinear function block is selected to reduce or substantially compensate for any nonlinearity introduced by the sensor circuitry and / or sensor system.

[0019] It can measure physical quantities directly or indirectly.

[0020] The sensor can be any type of sensor or transducer, such as an accelerometer, magnetic sensor, MEMS sensor, infrared (IR) sensor, or frequency sensor.

[0021] The characteristics of a physical quantity can be amplitude or phase. The at least one signal can indicate the input characteristics of the physical quantity, such as the phase or amplitude of the physical quantity.

[0022] The “first signal” can be an estimate of a physical quantity and can also be called an “uncorrected signal”.

[0023] This sensor circuit is particularly well-suited for capturing “fast” signals and performs “linear correction” even at high speeds. In an embodiment, the signal acquisition circuit is capable of sampling the input signal, digitizing the signal, and processing the signal at a symbol rate ranging from about 100 kHz to about 10 MHz, or from about 200 kHz to about 5 MHz, or from about 250 kHz to about 4 MHz, or from about 500 kHz to about 2.0 MHz.

[0024] When implemented in the digital domain, the processing circuitry typically operates at a clock frequency that is a factor of approximately 2 to 64 times higher than the symbol rate, or a factor of 8 to 32 times higher (e.g., approximately 10 times higher, or approximately 16 times higher, or approximately 20 times higher).

[0025] In a particular embodiment, the processing circuitry can operate at a frequency of approximately 10 to 30 MHz.

[0026] In an embodiment, the sensor circuit is a current sensor circuit for measuring current (e.g., current flowing through a busbar), and the current sensor circuit includes at least one magnetic sensor element (e.g., at least one Hall element, such as a horizontal Hall element, a vertical Hall element, or an MR element) configured to measure the magnetic field generated by the current flowing through the busbar. This sensor circuit is preferably implemented in a single semiconductor substrate (e.g., a silicon substrate). This substrate may be packaged in a molded package or a ceramic package, also referred to as a "chip," and may have multiple pins extending from the package. The purpose of the processing circuitry may be to correct for nonlinearity in the conversion from current to magnetic field, or nonlinearity in the conversion from magnetic field value to amplitude, or both. Nonlinearity may be introduced, for example, by magnetic saturation (e.g., by an integrated magnetic concentrator), by amplifier offset or gain offset, by the skin effect, etc.

[0027] In an embodiment, the sensor circuit is a position sensor circuit for measuring the position relative to a sensor device (e.g., the linear or angular position of a magnetic source (e.g., a permanent magnet), or vice versa. The position sensor circuit may include multiple magnetic sensor elements (e.g., at least one Hall element, such as a horizontal Hall element, a vertical Hall element, or an MR element) configured to measure the magnetic field generated by the magnetic source. The multiple magnetic sensor elements may be configured to measure two orthogonal magnetic field components or two orthogonal magnetic field gradients. Thus, the first sensor signal may be substantially phase-shifted by 90° relative to the second sensor signal. The processing circuit may be further configured to calculate an angle (or phase) using an angle measurement function (e.g., an arctangent function) of these signals and convert the angle into a position. The sensor circuit is preferably implemented in a single semiconductor substrate (e.g., a silicon substrate). This substrate may be packaged in a molded package or a ceramic package, also referred to as a "chip," and may have multiple pins extending from the package. The purpose of the processing circuit may be to correct for nonlinearities in the conversion from mechanical position to magnetic field, or from magnetic field values ​​to angles, or both. Nonlinearity can be introduced, for example, by one or more of the following: magnetic saturation (e.g., integrated magnetic concentrator), nonideal magnetization of the magnet, linear or axial offset or mechanical tilt of the magnet relative to the sensor device, offset or gain offset by the amplifier, etc.

[0028] In an embodiment, the sensor circuit is a position sensor circuit for measuring the position (e.g., linear or angular position) of a movable target (e.g., a metallic or conductive target) relative to a printed circuit board. The printed circuit board may include multiple coils, including at least one transmitter coil and at least two receiver coils. The at least two receiver coils may be referred to as magnetic sensors or magnetic sensor elements. In an embodiment, the printed circuit board includes three receiver coils configured to provide three modulated signals, and processing circuitry may be configured to demodulate these three signals. These three signals may be phase-shifted by 120°. The processing circuitry may be further configured to convert the three signals into two orthogonal signals using a transformation (e.g., a Clarke transform). Thus, the first sensor signal may be substantially phase-shifted by 90° relative to the second sensor signal. The processing circuitry may be further configured to calculate an angle (or phase) using an angle measurement function (e.g., an arctangent function) of these signals and convert the angle into a position. The processing circuitry and correction circuitry are preferably implemented in a single semiconductor substrate (e.g., a silicon substrate). This substrate may be packaged in a molded package or a ceramic package, also referred to as a "chip," and may have multiple pins extending from the package. The purpose of the processing circuit may be to correct the nonlinearity of the conversion from mechanical position to magnetic field, or the nonlinearity of the conversion from magnetic field value to angle, or both. Nonlinearity may be introduced, for example, by one or more of the following: magnetic saturation (e.g., by integrated magnetic concentrators), non-idealities in coil layout, offset or mechanical tilt of the target relative to the coil, non-idealities in demodulation, amplifier offset or gain offset, etc.

[0029] The physical quantity to be measured can be selected from the following groups: angular position, linear position, current, acceleration, pressure, force, torque, frequency, temperature, radiation intensity, light intensity, and light waveform amplitude.

[0030] At least one sensor or transducer can measure the physical quantity itself, or can measure a second quantity related to the physical quantity, for example: the physical quantity can be the angular position of a magnet, and the second quantity can be the magnetic field value.

[0031] In this embodiment, the corrected output value has improved linearity relative to the physical quantity. This is improved by stating that "within the measurement range, the linear regression coefficient of the corrected output signal is relative to the magnitude of the physical quantity to be measured," i.e., it is a value closer to 1.0, which can be expressed, for example, mathematically.

[0032] A frequency-dependent filter can be a noise reduction filter. This filter can have low-pass or band-pass characteristics. The noise to be reduced can be thermal noise. The noise to be reduced can have a frequency higher than a predefined frequency. In other words, the noise reduction filter can have a transfer function that attenuates frequencies exceeding a predefined frequency.

[0033] In some embodiments, the filter may include multiple different frequency-dependent filters, one of which is selected, for example, depending on the rate of change of the signal.

[0034] The at least one signal can be an electrical signal, such as a voltage signal or a current signal, or an optical signal.

[0035] A non-linear function block can be a non-linear scaler.

[0036] In the embodiments, the nonlinear function block is memoryless, meaning it does not contain memory elements such as flip-flops or digital registers.

[0037] In an embodiment, the nonlinear function block includes at least one memory element such as a flip-flop or a digital register.

[0038] In this embodiment, the signal acquisition circuit includes at least two sensors.

[0039] In one embodiment, the signal acquisition circuit is configured to provide at least two analog signals, and the processing circuit is implemented at least partially in the analog domain.

[0040] In this embodiment, the signal acquisition circuitry is configured to provide at least two digital signals, and the processing circuitry is implemented entirely in the digital domain. The advantage of such an embodiment is that the main portion of the circuitry is implemented in the digital domain, which typically provides lower manufacturing tolerances, easier testing, and generally improved accuracy.

[0041] In an embodiment, the combiner is a digital combiner, such as a digital linear combiner, such as an adder or subtractor block, or a multiplier, or a complex multiplier (i.e., configured to perform multiplication of two complex signals, each having a real part and an imaginary part), or a complex multiplier of the complex conjugate of the first and second signals.

[0042] In this embodiment, the nonlinear function is defined by a plurality of parameters determined during the calibration process.

[0043] Nonlinear functions can be implemented, for example, using lookup tables with or without interpolation, or as piecewise linear approximations, through multiple points (e.g., from 4 to 32 points) determined during the calibration process.

[0044] The main difference from existing technical solutions is that the nonlinear function is incorporated into the feedback path rather than into a block in the forward path.

[0045] In the embodiment, the physical quantity has an input phase (e.g., θ). i ), and output signal (e.g., θ) 校正 ) is an indicator of the input phase (e.g., θ) iThe phase signal of the input signal; and the signal acquisition circuit includes multiple sensors configured to provide multiple input signals (e.g., v1, v2), each input signal being the input phase (e.g., θ). i The first sub-circuit further includes functions configured to provide a phase response to the input (e.g., θ). i Estimates of (e.g., θ) 计算 ;θ 估计 A phase generator; and wherein processing circuitry is configured to provide an output phase (e.g., θ). 校正 ), thus having a phase relative to the input (e.g., θ) i Improved accuracy (e.g., improved linearity).

[0046] Depending on the implementation, the "phase generator" can be a "phase calculator" or a "phase estimator".

[0047] This sensor circuit is particularly suitable for measuring periodic physical quantities, and the information determined by the sensor device is encoded in the phase of the signal.

[0048] In the embodiment, there are at least two sensors configured to provide two input signals with a basic phase shift of 90°.

[0049] In one embodiment, there are at least three sensors configured to provide three input signals with a basic phase shift of 120°.

[0050] The sensor circuit can be further configured to output the phase value (θ) in a known manner. o Convert to position, for example, convert to linear to angular position.

[0051] In one embodiment, the signal acquisition circuit includes at least one magnetic sensor configured to measure a magnetic field signal associated with the physical quantity to be measured.

[0052] In one embodiment, the signal acquisition circuit includes at least two magnetic sensors, each configured to measure the magnetic field (e.g., at least two magnetic field components or at least two magnetic field gradients) associated with the physical quantity to be measured.

[0053] In one embodiment, the signal acquisition circuit includes at least three magnetic sensors, each configured to measure the magnetic field (e.g., at least two magnetic field components or at least two magnetic field gradients) associated with the physical quantity to be measured.

[0054] In embodiments having at least two magnetic sensors, preferably, these at least two magnetic sensors are arranged to provide two sinusoidal signals with a substantially 90° phase shift and preferably also having substantially the same amplitude.

[0055] In embodiments having at least three magnetic sensors, preferably, these at least three magnetic sensors are arranged to provide three sinusoidal signals with a substantially 120° phase shift and preferably also having substantially the same amplitude.

[0056] In an embodiment (e.g., shown in Figures 1 through 4), the first sub-circuit includes the phase estimator, followed by the combiner, and the phase estimator is arranged to receive the at least one input signal (e.g., v1, v2) and convert it into the phase signal (e.g., θ). 计算 ), and wherein the combiner is configured to receive and combine the phase signal (e.g., θ). 计算 ) and the feedback signal (e.g., θ) fb1 ;θ fb2 ).

[0057] In one embodiment, the second sub-circuit includes a nonlinear function block arranged to receive and modify the filtered signal (e.g., θ) using a (e.g., memoryless) nonlinear function. 校正 ); and the at least one feedback signal (e.g., θ) fb1 ;θ fb2 ) is derived from the modified signal.

[0058] In an embodiment, the filter has a frequency-dependent transformation function T(s), wherein T(s) is chosen such that [T(s)-1] has at least one zero at DC, and wherein a nonlinear function block is configured to be used at θ fb1 =f(θ) o )-θ o The feedback signal is output in the form of θ, where θ fb1 It is the feedback signal, f() is a predefined nonlinear function, and θ o This is the output value.

[0059] In practice, the function f() is preferably chosen such that f(θ) o ) is the input (θ) i The function f() can be estimated through simulation or calibration testing (e.g., off-line testing in production). The function f() can be specified, for example, by multiple values, coefficients, or coordinates stored in the device's non-volatile memory (e.g., flash memory or EEPROM). Predefined nonlinear functions f() can be implemented using lookup tables with or without interpolation. Predefined nonlinear functions f() can also be implemented using piecewise linear approximations.

[0060] In the embodiment, the transformation function T(s) is selected such that [T(s)-1] has at least two zeros at DC.

[0061] "At DC" means "at 0 Hz". Such a filter allows ramp signals with zero steady-state error to follow. Such a filter T is sometimes called a zero-wait-time filter (ZLF).

[0062] In the embodiment, the filter has a frequency-dependent transformation function H(s), and H(s) has at least one pole at DC, and the nonlinear function block is configured to be used at θ fb =f(θ) o The feedback signal is output in the form of θ. fb It is the feedback signal, f() is a predefined nonlinear function, and θ o This is the output value.

[0063] In practice, the function f() is preferably chosen such that f(θ) o ) is the input (θ) i The estimation of a function f() can be achieved, for example, using a lookup table with or without interpolation, or using a piecewise linear approximation. The function f() can be determined through simulation or through calibration testing (e.g., through off-line testing in production). The function f() can be specified, for example, by multiple values ​​or multiple coefficients or coordinates stored in the device's non-volatile memory (e.g., flash memory or EEPROM). Predefined nonlinear functions f() can be implemented using lookup tables with or without interpolation. Predefined nonlinear functions f() can be implemented using piecewise linear approximations.

[0064] In the embodiment, the transformation function H(s) has at least two poles at DC.

[0065] "At DC" means "at 0 Hz".

[0066] In (for example) Figure 6 or Figure 7 In the embodiment shown, the first sub-circuit includes the combiner, followed by the phase generator, and the combiner is arranged to receive and combine the at least one input signal (e.g., v1, v2) and the at least one feedback signal (e.g., fbi; fbq), and the phase generator is configured to convert the combined signal into the phase signal (e.g., θ). 估计 ).

[0067] In one embodiment, the second sub-circuit includes a nonlinear functional block arranged to receive and modify the filtered signal (e.g., θ) using a (e.g., memoryless) nonlinear function. 校正The second sub-circuit further includes a phase-to-I / Q converter configured to receive the modified signal and convert it into at least two component signals; and a feedback signal (e.g., fbi; fbq) is derived from these component signals.

[0068] In an embodiment, the signal acquisition circuit includes a plurality of magnetic sensing elements (e.g., at least two Hall elements, or at least two MR elements, or at least two coils) configured to measure the magnetic field associated with the physical quantity to be measured, and configured to provide a plurality of signals (e.g., v1, v2), each signal being the input phase of the physical quantity (e.g., θ). i The processing circuitry (including a phase estimator or an angle estimator) is configured to derive a representation of the input phase (e.g., θ) from the plurality of signals (e.g., v1, v2). i The uncorrected phase value (e.g., θ) 计算 The correction circuit is arranged to receive the uncorrected phase value (e.g., θ). 计算 ), and is used to provide a corrected output phase value (e.g., θ) with reduced error. 校正 ), for example, having a phase relative to the input (e.g., θ) i The improved linearity; and i) the combiner is arranged to receive and combine the uncorrected phase values ​​(e.g., θ). 计算 ) and feedback signals (e.g., θfb1; θfb2); and ii) a frequency correlation filter is configured to receive and filter the output of the combiner and to generate the corrected output phase value (e.g., θfb1; θfb2). 校正 ); and iii) the nonlinear function block is configured to receive the corrected output phase value (e.g., θ). 校正 ).

[0069] The physical quantity can be, for example, the linear or angular position of a magnet, or the value of an AC current. The phase value can be an angle value. The processing circuit can be a phase estimator or an angle estimator. The combiner can be an adder or a subtractor. The filter can be a noise filter.

[0070] Ideally, the phase of the magnetic field should be the same as the phase of the physical quantity. However, in practice, due to factors such as mechanical misalignment of the magnet or imperfect PCB layout of the sensing angle sensor, a (first) nonlinear relationship may exist. Furthermore, ideally, the phase value provided by the processing circuit should be the same as the phase of the magnetic field. However, in practice, due to defects in the processing circuit, a (second) nonlinear relationship may exist. This can occur, for example, if the processing circuit is a tracking loop simulating the arctangent function.

[0071] The advantage of the correction circuit is that it can reduce or substantially compensate for the first and / or second nonlinearities created inside and / or outside the sensor device.

[0072] The inventors were surprised to find that the feedback signal had to be injected before the frequency-dependent filter, otherwise the nonlinear correction would not work and might even make the signal worse.

[0073] In an embodiment, the processing circuitry introduces nonlinearity (e.g., NL2); and the nonlinearity functional block is configured to at least reduce or substantially eliminate the nonlinearity (e.g., NL2) introduced by the processing circuitry.

[0074] In other words, in this embodiment, the value provided by the processing circuitry (e.g., the phase value provided by the phase calculator) can be represented or approximated by a (desired) linear function plus a (undesired) nonlinear error function (NL2) at its input.

[0075] In one embodiment, the processing circuitry includes a tracking loop that introduces the nonlinearity (e.g., NL2).

[0076] In some embodiments, the first and second signals provided by the tracking loop are analog signals. In other embodiments, the first and second signals provided by the tracking loop are digital signals.

[0077] In one embodiment, the tracking loop includes at least four magnetically sensitive elements; and the processing circuitry is configured to generate the uncorrected phase value based on a coarse signal and a fine signal, wherein the coarse signal is generated based on the symbol of a digital signal.

[0078] The advantage of this embodiment is that the processing circuit can provide an estimate of the arctangent function at relatively high speeds (e.g., at at least 100 MHz, or at least 200 MHz, or at least 500 MHz, or at least 1000 MHz), but the absolute error of the estimate can be approximately ±4°.

[0079] The advantage of the correction circuit is that, even at such high speeds, it can reduce the error to less than ±1°, or less than ±0.5°, or less than ±0.25°.

[0080] According to a second aspect, the present invention also provides a position sensor system comprising: a magnetic source configured to generate an indicator of mechanical position (e.g., θ). 机械 The phase of the magnetic field; and the magnetic sensor circuit according to the first aspect; wherein the input phase of the magnetic field sensed by the magnetic sensor circuit can be expressed as the mechanical position (e.g., θ). 机械The sum of a linear function of the mechanical position and a nonlinear error function (e.g., NL1); and wherein the nonlinear function block is configured to reduce or at least partially compensate for or substantially eliminate the nonlinear error function (e.g., NL1).

[0081] In an embodiment, the second sub-circuit is configured to reduce or substantially eliminate errors (e.g., higher harmonics) that are related to or caused by the mechanical non-idealities of a magnetic source located outside the magnetic sensor circuit.

[0082] In an embodiment, the magnetic source is a permanent magnet movable relative to the magnetic sensor circuit, or vice versa; and the second sub-circuit is configured to reduce or substantially eliminate errors (e.g., higher harmonics) related to mechanical mounting aspects (or mechanical non-ideals), such as those selected from the group consisting of position offset, tilt, and eccentricity.

[0083] In one embodiment, the position sensor system includes: a printed circuit board including a plurality of coils; a target movable relative to the plurality of coils; and the magnetic sensor circuit; and a second sub-circuit configured to reduce or substantially eliminate errors (e.g., higher harmonics) related to mechanical mounting aspects (or mechanical non-ideals) of the target, such as selected from the group consisting of: position offset, tilt, eccentricity, and / or related to the layout of the plurality of coils.

[0084] According to a third aspect, the present invention also provides a current sensor system comprising: a current conductor (e.g., a busbar or an integrated electrical conductor portion) for conducting a current to be measured; and a sensor circuit according to the first aspect, the sensor circuit being configured to measure a magnetic field generated by the current to be measured.

[0085] Specific and preferred aspects of the invention are set forth in the appended independent and dependent claims. Features from the dependent claims may be suitably combined with features of the independent claims and other dependent claims, and not merely as expressly set forth in the claims.

[0086] These and other aspects of the invention will be apparent from the embodiments described herein, and are illustrated with reference to these embodiments. Attached Figure Description

[0087] Figure 1(a) is a schematic diagram of an angular position sensor system according to an embodiment of the present invention, which includes a permanent magnet and a sensor circuit configured to measure the angular position of the magnet. Nonlinearity (or non-ideality) can be introduced in several places. In the example, a first nonlinearity can be introduced when converting a mechanical angle into a magnetic field value, and a second nonlinearity can be introduced within the sensor device when converting a magnetic signal into an electrical signal via a magnetic sensor element or circuit, and a third nonlinearity can be introduced when calculating or estimating the angular position based on the signal provided by the sensor element. The sensor circuit includes correction circuitry operating in the angular domain and is configured to reduce these nonlinearities.

[0088] Figure 1(b) shows an example of a combination of the first, second, and third nonlinearities, illustrated as the (magnetic) angle θ. 计算 and mechanical angle θ 机械 The non-linear relationship between them.

[0089] Figure 2(a) shows a block diagram of the classic correction circuit used to reduce the nonlinearity described in Figures 1(a) and 1(b).

[0090] Figure 2(b) shows the inverse function of the function shown in Figure 1(b), which is highly linear when combined with the nonlinear function in Figure 1(b).

[0091] Figures 3(a) and 3(b) show block diagrams of the first and second processing circuits proposed in this invention, each configured to calculate angles and reduce or correct nonlinear errors. This processing circuit can be used in the system of Figure 1(a). In the embodiments of Figures 3(a) and 3(b), the processing circuit includes a phase calculator, followed by a correction circuit comprising a combiner and a filter arranged in a closed loop, and a nonlinear function block. The correction circuit is arranged downstream (behind) the phase calculator, so the combiner, filter, and nonlinear function block operate in the angle domain.

[0092] Figure 4(a) shows an illustrative example of a circuit with the topology shown in Figure 3(a), wherein the processing circuit is configured to determine the angle using a “tracking loop”.

[0093] Figure 4(b) shows the angle value θ calculated by the angle calculator 427 of Figure 4(a). 计算 Illustrative examples of typical errors between them.

[0094] Figure 4(c) shows the corrected angle θ provided by the correction circuit 428 of Figure 4(a). 校正 The typical error between them is presented as an illustrative example of a function of the input angle.

[0095] Figure 5(a) is a schematic representation of a sensing angular position sensor system according to an embodiment of the present invention. The sensing angular position sensor system includes: a printed circuit board (PCB) including a plurality of coils; a conductive target; and sensor circuitry configured to measure the angular position of the target. Nonlinearity (or non-ideality) can be introduced in several places. In the example, a first nonlinearity can be introduced when converting a mechanical angle to a magnetic field value, a second nonlinearity can be introduced in the receiver and demodulation circuitry, and a third nonlinearity can be introduced by a phase calculator or phase estimator within the sensor device.

[0096] Figure 5(b) shows an illustrative block diagram of a sensing angular position sensor system, which includes a printed circuit board comprising a transmitter coil and three receiver coils. The system further includes sensor circuitry configured to calculate the angular position in a manner that reduces the aforementioned nonlinearity and to output the angular position to an external processor (e.g., an electronic control unit, ECU).

[0097] Figure 6 Another embodiment of the invention is shown, which has a signal acquisition circuit similar to that of FIG. 1(a), but with an additional processing circuit for determining angular position and reducing nonlinear errors. The processing circuit includes a combiner, a phase estimator, a filter, a nonlinear function block, and a phase-to-I / Q converter arranged in a closed loop, wherein the combiner operates in the I / Q domain; and wherein the filter and the nonlinear function block operate in the angular domain. The I / Q domain is located upstream (before) the phase estimator and downstream (after) the phase-to-I / Q converter. The angular domain is located downstream (after) the phase estimator and upstream (before) the phase-to-I / Q converter.

[0098] Figure 7 Another embodiment of the invention is shown, which has a signal acquisition circuit similar to that in FIG5(a), and has Figure 6 The processing circuit.

[0099] The accompanying drawings are illustrative only and not restrictive. In the drawings, some elements may be enlarged and not drawn to scale for illustrative purposes. No reference numerals in the claims should be construed as limiting. In different drawings, the same or similar reference numerals (e.g., having the same module 100) generally refer to the same or similar elements. Detailed Implementation

[0100] The invention will be described with reference to specific embodiments and particular drawings, but the invention is not limited thereto but is defined only by the claims.

[0101] The terms "first," "second," etc., used in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a temporal, spatial, hierarchical, or any other order. It should be understood that such terms are interchangeable where appropriate, and embodiments of the invention described herein can be operated in a different order than those described or illustrated herein.

[0102] The terms top, bottom, etc., used in the specification and claims are for descriptive purposes and are not necessarily used to describe relative positions. It should be understood that the terms used so are interchangeable where appropriate, and the embodiments of the invention described herein can operate in orientations different from those described or illustrated herein.

[0103] It should be noted that the term "comprising" as used in the claims should not be construed as limiting oneself to the means listed thereafter; it does not exclude other elements or steps. Therefore, the term should be interpreted as specifying the presence of the features, integers, steps, or components stated 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 statement "device comprising means A and B" should not be limited to a device consisting solely of components A and B. It means that for the purposes of this invention, the only relevant components of the device are A and B.

[0104] Throughout this specification, the reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Therefore, the phrase "in one embodiment" or "in an embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, as will be obvious to those skilled in the art from this disclosure, particular features, structures, or characteristics can be combined in any suitable manner.

[0105] Similarly, it should be understood that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, drawing, or description for the purpose of simplifying the disclosure and aiding in the understanding of one or more inventive aspects. However, this method of disclosure should not be construed as reflecting an intention to claim more features than are expressly recited in each claim. Rather, as reflected in the appended claims, inventive aspects exist in fewer features than all the features of a single foregoing disclosed embodiment. Therefore, the claims appended to the Detailed Description are thus explicitly incorporated into this Detailed Description, wherein each claim itself represents a separate embodiment of the invention.

[0106] Furthermore, while some embodiments described herein include features that are included in other embodiments but not others, it will be understood by those skilled in the art that combinations of features from different embodiments are intended to fall within the scope of the invention and form different embodiments. For example, any embodiment of the claimed embodiments in the appended claims can be used in any combination.

[0107] Numerous specific details are set forth in the description provided herein. However, it should be understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this description.

[0108] In this document, unless otherwise expressly stated, the terms “phase calculator” and “angle calculator” are used interchangeably.

[0109] In this document, the term "phase generator" is used as a general term and encompasses the terms "phase calculator" and "phase estimator." Although the term "phase calculator" indicates that the results are more accurate than "phase estimator," these three terms are used interchangeably in this document.

[0110] The phrase "reduce error within the measurement range" can mean: reduce the maximum error, average error, or total squared error (e.g., the integral sum of squared errors) within the measurement range.

[0111] "Improved linearity" means reducing the error between the measured curve and the ideal curve.

[0112] In embodiments of the present invention, "improved linearity" may mean "having improved linear regression coefficients", which means "having linear regression factors closer to 1.000".

[0113] "5krpm electrical" means "the electrical signal rotates or swivels at 5000 revolutions per minute". For example, if the target of a position sensor system contains five lobes and is mounted on a shaft rotating at an angular velocity (mechanical) of 1000 revolutions per minute, then the angular velocity of the electrical signal is 5krpm electrical.

[0114] This invention relates to the field of sensor systems and devices, and may include various types of sensors, such as one or more optical sensors, one or more magnetic sensors, one or more accelerometers, etc. The principles of this invention will be primarily explained with respect to magnetic position sensor systems and angular position sensor systems including permanent magnets; however, the invention is not limited thereto and is more generally applicable to other types of sensors and systems, particularly magnetic sensors and systems.

[0115] Figure 1(a) is a schematic representation of an angular position sensor system 100 including a permanent magnet 110 and a sensor circuit 120. The permanent magnet 110 may be a bipolar magnet, a quadrupole magnet, or a magnet including more than four poles. The magnet 110 shown in Figure 1(a) is rotatable about a rotation axis, and the sensor circuit 120 is configured to determine a mechanical angle θ. 机械 .

[0116] The angular position θ of magnet 110 is determined by measuring the characteristics of the magnetic field generated by magnet 110 using one or more magnetic sensors. 机械 The circuits and methods are known in the art, for example from WO9854547(A1) or WO2014029885(A1), to name just a few. Without going into detail, it is sufficient to know that the angular position of magnet 110 can be determined, for example, by measuring a first magnetic signal that is a sine function of mechanical position and a second magnetic signal that is a cosine function of mechanical position, and by calculating the arctangent of the ratio of the sine and cosine signals.

[0117] For example, this can be achieved by the sensor circuit 120 shown in FIG1(a), which includes a first sensor element 121 providing a first sensor signal s1 and a second sensor element 122 providing a second sensor signal s2. The first sensor element 121 and the second sensor element 122 may be, for example, a horizontal Hall element, a vertical Hall element, a magnetoresistive element (MR element), etc.

[0118] The biasing and readout circuitry of the magnetic sensor element is known in the art and is not the focus of this invention, so it does not need to be explained in more detail here. In the example of FIG1(a), the readout circuit 126 may include at least one analog-to-digital converter (ADC), and the readout circuit 126 may provide two digital signals v1, v2 to the processing block 150.

[0119] However, in practice, signals v1 and v2 are often not perfect sine and cosine signals for various reasons. One reason could be that the first magnetic field component measured at a first sensor position at a predefined distance from the magnet (e.g., about 1.0 mm) may not be a perfect sine signal, and / or the second magnetic field component measured at a second sensor position may not be a perfect cosine signal. This can occur, for example, if the sensor device is not perfectly aligned with the magnet, or is tilted, or if the magnet is imperfect, etc., resulting in nonlinearity. This is schematically indicated in Figure 1(a) by the symbol “NL1”, representing the first nonlinearity or first non-ideality.

[0120] However, bias and readout circuits are often not perfect either, for example, due to amplifier offset or gain offset, or nonlinearity caused by analog-to-digital converters. This is schematically indicated in Figure 1(a) by the symbol "NL2".

[0121] In the sensor circuit of Figure 1(a), signals v1 and v2 are applied to processing circuit 150. Processing circuit 150 includes a "phase generator," also referred to herein as a "phase calculator" or "angle calculator." This block 127 can be configured to determine (e.g., calculate) the angle value θ based on the arctangent of the ratio of v1 and v2. 计算 However, in practice, the phase calculator 127 provides the value θ 计算 This is only an approximation, and depending on the implementation, it may deviate more or less from arctan(v1 / v2), for example, due to the limited number of bits, and / or due to the way the division is implemented, and / or due to the way the arctangent function is implemented (e.g., using an iterative formula, or as a Taylor series, or as a lookup table with / without interpolation, etc.). In other words, the phase calculator 127 may also introduce nonlinearity (or non-ideality), schematically represented by the symbol NL3.

[0122] In practice, the effects of various nonlinear NL1, NL2 and NL3 are often cumulative and can be represented by combined or global nonlinear NLo, an example of which is shown in Figure 1(b) as an illustrative example only.

[0123] The inventors of this invention seek to find a solution to improve the accuracy of sensor devices (excluding magnets) and / or sensor systems (including magnets) by reducing at least one of the nonlinear errors, preferably all of the nonlinear errors, and more preferably substantially eliminating or compensating for the overall nonlinear error.

[0124] Figure 2(a) shows the classic solution to this problem.

[0125] Figure 2(a) shows a block diagram of a correction circuit 228 arranged to correct the signal provided by the phase calculator 227.

[0126] Figure 2(b) shows the inverse function of the function shown in Figure 1(b).

[0127] The correction circuit 228 is configured to receive the calculated angle θ from the phase calculator block 227. 计算 And use a predefined remapping function to convert the value to a corrected value θ. 校正For example, a piecewise linear correction function can be used, interconnecting a finite number of points (e.g., from 4 to 32 points, such as about 8 points, or about 12 points, or about 16 points, or about 24 points). The nonlinear function, or the coordinates of these points, can be determined, for example, during calibration testing, by calculating the angle value θ. 计算 The magnet is positioned at multiple predefined angular locations (e.g., in multiples of 30°) during calibration testing, and the value is stored in the sensor device's non-volatile memory. Later, during normal operation, the sensor device can subsequently correct the calculated value θ between these points using piecewise linear interpolation. 计算 This reduces nonlinear errors.

[0128] By selecting a piecewise linear correction function as an approximation of the inverse function of the combination of the aforementioned nonlinearities NL1, NL2, and NL3, nonlinearity can be significantly reduced. This technique is used in commercial products and is well-known in the art, therefore it need not be described in more detail here.

[0129] The correction circuit 228 may optionally include a noise filter 230 (e.g., with low-pass characteristics). This can help smooth the output signal in the case of a magnet rotating relatively slowly (e.g., at an angular velocity of less than 100 rpm). For example, the noise filter can be implemented as a low-pass FIR (finite impulse response) filter or an exponential moving average (EMA) filter. In practical implementation, the noise filter can be disabled or bypassed.

[0130] However, during the design of the new sensor device, the inventors of the present invention discovered that under certain conditions, the solutions proposed in Figures 2(a) and 2(b) did not work well and actually made the results less accurate than those without the correction circuit 228.

[0131] Upon further investigation of the problem, it was found that the correction circuit 228 in Figure 2(a) works well at relatively low speeds, but does not work well at relatively high speeds (e.g., around 100 krpm or higher).

[0132] Hoping to reduce one or more of the nonlinearities at such high speeds, and preferably all of them, the inventors began experimenting with various circuit topologies, and they were surprised to find in Figures 3(a) and 3(b) Figure 6 and Figure 7 The four circuit topologies shown in the figure yield satisfactory results.

[0133] Figure 3(a) shows a block diagram of the first processing circuit 350 proposed in this invention, which includes a phase calculator 327 followed by a correction circuit 328 for reducing or correcting one or more nonlinear errors. This arrangement can be used in a sensor circuit similar to that shown in Figure 1(a) to reduce one or more or all of the nonlinearities NL1, NL2, NL3.

[0134] As can be seen, the correction circuit 328 is arranged to receive the uncorrected signal θ from the phase calculator 327. 计算 And used to provide a corrected output signal θ 校正 The correction circuit 328 includes:

[0135] i) Combiner 331, which is arranged to receive and combine the uncorrected signal θ 计算 and feedback signal θ fb1 ,as well as

[0136] ii) Frequency correlation filter 332, configured to receive and filter the output of the combiner 331, and to generate the corrected output signal θ. 校正 ,as well as

[0137] iii) Nonlinear function block 333, which is configured to receive the corrected output signal θ 校正 And used to generate the feedback signal θ using a nonlinear function f(θ) (e.g., the inverse function shown in Figure 2(b), or an approximation thereof, such as a piecewise linear approximation). fb1 .

[0138] The frequency-dependent filter 332 has a conversion characteristic T(s), where [T(s)-1] has at least one zero at DC (i.e., 0 Hz), but preferably at least two zeros at DC. The latter is called a zero-wait-time filter (ZLF).

[0139] The feedback signal θ provided by nonlinear function block 333 fb1 This can be expressed by the following formula: θ fb1 = f(θ0) - θ0, where θ0 is the output value provided by the filter T(s), and f(θ0) is the nonlinear transformation of the output value.

[0140] Combiner 331 can be configured to provide the output as the uncorrected value θ 计算 and feedback signal θ fb1 Linear combinations, such as addition or subtraction.

[0141] Simulations show that the circuit works well even at relatively high speeds, such as up to about 200krpm, or even up to 300krpm, or even up to 400krpm, or even up to 500krpm, or even up to 600krpm, or even up to 700krpm.

[0142] Note that the correction circuit 328 can be implemented entirely in the digital domain.

[0143] In an embodiment, the phase calculator circuit 327 may be further configured to determine the angular velocity ω and / or angular acceleration α, for example, as a first and second time derivative of the angular position, and one or both of these values ​​may optionally be provided to the correction circuit 328. Taking into account one or both of the angular velocity ω and / or angular acceleration α, the correction circuit 328 may be configured to adjust the filter characteristic T(s) and / or the nonlinear function f(). For example, in a particular implementation, the correction circuit 328 includes two filters, one of which is selected depending on whether the angular velocity is above or below a predefined threshold.

[0144] In Figure 3(a), the processing block 327 that provides an estimate of the physical value to be measured is a phase calculator that can perform the arctangent function of the ratio of signals v1 and v2, but the invention is not limited thereto, and another processing block 327 may also be used.

[0145] Figure 3(b) shows a block diagram of the second processing circuit 350' proposed in this invention, which includes a phase calculator 327' followed by a correction circuit 328' for reducing or correcting nonlinear errors. This arrangement can also be used in a sensor circuit similar to that shown in Figure 1(a) to reduce one or more or all of the nonlinearities NL1, NL2, NL3. Processing circuit 350' is a variation of processing circuit 350. The phase calculator 327' in Figure 3(b) can be the same as the phase calculator 327 in Figure 3(a), but the correction circuit 328' is different.

[0146] As can be seen, the correction circuit 328' is arranged to receive the uncorrected value θ from the phase calculator 327'. 计算 And used to provide a corrected output signal θ 校正 The correction circuit 328' includes:

[0147] i) Combiner 331', which is arranged to receive and combine the uncorrected signal θ 计算 and feedback signal θ fb2 ,as well as

[0148] ii) Frequency correlation filter 332', which is configured to receive and filter the output of the combiner 331' and to generate the corrected output signal θ. 校正 ,as well as

[0149] iii) Nonlinear function block 333', which is configured to receive the corrected output signal θ 校正 And used to generate the feedback signal θ using a nonlinear function f(θ). fb2 .

[0150] The frequency-dependent filter 332' has a conversion characteristic H(s), which has at least one pole at DC (i.e., 0 Hz), but preferably at least two poles at DC.

[0151] The feedback signal θ provided by the nonlinear function block 333' fb2 This can be expressed by the following formula: θ fb2 = f(θ0), where θ0 is the output value provided by the filter H(s), and f(θ0) is the nonlinear transformation of the output signal.

[0152] Combiner 331' can be configured to provide an output as an uncorrected signal θ 计算 and feedback signal θ fb2 Linear combinations, such as addition or subtraction.

[0153] In a variant (not shown), block 333 of Figure 3(a) and / or block 333' of Figure 3(b) may include one or more storage elements, and / or one or more delay elements and / or one or more scalers, and may provide a nonlinear function of the value θ0 at its input and a combination of one or more previous values.

[0154] In an embodiment, block 333 of FIG3(a) and / or block 333' of FIG3(b) may include a piecewise linear interpolator and an FIR filter, and are configured to provide a combination of a piecewise linear transform version and an FIR filter version of the value θ0 applied at its input.

[0155] In the embodiment, block 333 of FIG3(a) and / or block 333' of FIG3(b) do not contain FIR filters or delay elements, but only the piecewise linear interpolator.

[0156] In the same case, the phase calculator 327' may optionally provide the correction circuit 328' with one or both of angular velocity ω and / or angular acceleration α, and the correction circuit 328' may adjust its behavior based on one or both of these values ​​(velocity and / or acceleration).

[0157] In Figure 3(b), the phase calculator 327' that provides an estimate of the physical value to be measured can perform an arctangent function of the ratio of signals v1 and v2, but the invention is not limited thereto, and another processing block can also be used.

[0158] Figure 4(a) shows an illustrative example of the implementation of the circuit shown in Figure 3(a), where the "phase generator" or "angle calculator" 427 is implemented using a so-called "tracking loop". In a specific embodiment, the tracking loop may be implemented in more detail as in EP3528388(A1), which is incorporated herein by reference in its entirety, especially the circuit shown in Figure 2, and the corresponding text.

[0159] As can be seen, the processing circuit 450 includes an angle calculator 427, which includes a tracking loop, and the processing circuit 450 further includes a correction circuit 428, but the correction circuit 428 is arranged outside the tracking loop, downstream of the angle calculator 427.

[0160] The main advantage of this "tracking loop" is that it can be used to calculate, estimate, approximate, or simulate the arctangent function without actually requiring a programmable DSP (digital signal processor) or arithmetic unit.

[0161] Figure 4(b) shows the calculated angle value θ provided by the tracking loop 427 (e.g., implemented as described in EP3528388). 计算 An illustrative example of a typical error between the angle value corresponding to the one or more sensor signals applied as input. As can be seen, there is a predefined relationship between the angle value corresponding to the input signal(s) and the calculated value. As mentioned above, this error can be considered as a "nonlinear error" NL3.

[0162] Figure 4(c) shows the corrected angle θ provided by the correction circuit 428. 校正 The typical error between them serves as an illustrative example of the error as a function of the input angle "input". As can be seen, the correction circuit 428 is able to reduce the error of approximately ±4.0° shown in Figure 4(b) to only approximately ±0.2° shown in Figure 4(c), which is more than a factor of 10.

[0163] As mentioned above, the principles of the present invention are not limited to magnetic position sensor systems including magnets, such as those shown in FIG1(a), but can also be used in other types of sensor systems and circuits, such as those including one or more magnetic sensors, one or more optical sensors, one or more pressure sensors, one or more accelerometers, etc.

[0164] Figures 5(a) and 5(b) show schematic representations of a sensing angular position sensor system 500, which includes a printed circuit board (PCB) 513, sensor circuitry 520, and a conductive target 511. Sensor circuitry 520 includes signal acquisition circuitry 540 and processing circuitry 550. Signal acquisition circuitry 540 includes multiple coils, such as a transmitter coil and three receiver coils, which act as sensor elements 521, 522, and 523. Sensor circuitry 520 is configured to determine the angular position θ of target 511. 机械 .

[0165] Nonlinearity (or non-ideality) can be introduced in several places. For example, when considering mechanical angles θ... 机械 When converted to an electrical or magnetic signal (e.g., to three modulated AC signals), a first nonlinearity NL1 may be introduced; a second nonlinearity NL2 may be introduced by the "receiver and demodulation circuit" 526. This circuit may also include at least one analog-to-digital converter (ADC), and optionally, a Clarke transform circuit; when calculating the angular position θ based on the input signals v1, v2... 计算 At this time, the third nonlinearity NL3 can be introduced into the processing circuit 550 itself, for example, by the phase calculator 527. Nonlinearities NL1, NL2, and NL3 are shown for illustrative purposes only, and in practice, there may be more than three or fewer nonlinear sources, or other nonlinearities may exist, but the principles explained above remain unchanged.

[0166] Position sensors are well known in the art and therefore require no detailed explanation here. To understand the invention, it is necessary to know that an alternating signal (AC signal) is typically applied to an excitation coil (also called a transmitter coil), which generates an alternating magnetic field. As is known in the art, the transmitter coil can have a circular shape surrounding the receiver coil. This magnetic field is modulated by the angular position of the conductive target 511, which affects the signals s1, s2, s3 received by the receiver coils 521, 522, 523 as sensor elements. These signals can be converted into angular positions using known techniques (e.g., in “Receiver and Demodulation Circuit” 526). Some inductive sensor systems contain only two receiver coils arranged such that the received and demodulated signals are substantially phase-shifted by 90°.

[0167] In the example shown in Figure 5(b), there are three receiver coils arranged such that the received and demodulated signals are substantially phase-shifted by 120°. These three signals can be converted into orthogonal signals v1, v2 in a known manner (e.g., using a Clarke transform). The phase calculator 527 can then determine the angular position of the target based on these signals v1, v2. Furthermore, the correction circuit 528 can reduce any nonlinear errors and provide an angular position θ with improved accuracy to an external processor 540 (e.g., an electronic control unit (ECU)). 校正 The correction circuit 528 may have the topology shown in Figure 3(a) as described above or in Figure 3(b).

[0168] Of course, this is just an illustrative example of a position sensor, and many variations are possible. For example, many shapes of the target 511 are possible, and various arrangements of the coil are also possible, etc. (e.g., C-shaped, O-shaped). The phase calculator 527 can be implemented using a digital processor (e.g., a DSP), or using a lookup table or a tracking loop as described in Figure 4(a) above.

[0169] In a particular embodiment, the corrected angle θ 校正 The signals are converted into sine and cosine signals, which are then provided to the ECU. This type of implementation is particularly useful for backward compatibility with existing systems.

[0170] In the variant of the system shown in Figure 5(b), the correction circuit 528 is not implemented inside the sensor device, but in an external processor 540.

[0171] Return to reference Figures 1(a) to 5(b) Figures 1 through 5 disclose sensor circuits (e.g., 120) capable of reducing or substantially compensating for nonlinearities introduced internally or externally to the sensor circuit, up to very high speeds. These sensor circuits (e.g., 120) include signal acquisition circuitry (e.g., 140) and processing circuitry (e.g., 150). In these embodiments, the processing circuitry (e.g., 150) is configured to receive at least one input signal v1, v2, such as two sinusoidal input signals with a substantially 90° phase shift, or three sinusoidal signals with a substantially 120° phase shift. In these embodiments, the processing circuitry (e.g., 150) is configured to provide an output signal θ representing the physical quantity to be measured. 校正 For example, the angular position of an axis connected to a magnet or a conductive target.

[0172] Using the reference numerals of Figure 3(a), the processing circuits of Figures 1(a) and 5(a) comprise a closed loop consisting of: a first sub-circuit 360, the output of which is connected to a filter 332; the output of the filter 332 is connected to a second sub-circuit 333; and the output of the second sub-circuit 333 is fed back to the first sub-circuit 360. More specifically, in these embodiments:

[0173] - The first sub-circuit 360 is arranged to receive the at least one input signal v1, v2 and at least one feedback signal θ fb1 The first sub-circuit includes a phase generator 327 and a combiner 331, and provides a phase signal θ. 计算 Phase estimator 327 is followed by combiner 331.

[0174] - Filter 332 is a frequency-dependent filter configured to receive and filter phase θ 计算 And is configured to provide a filtered signal as the output signal θ 校正 ;

[0175] - The second sub-circuit 333 consists of a nonlinear function block 333, which is arranged to receive the filtered signal θ. 校正 As the input signal, it is used to convert the signal into a feedback signal θ using a nonlinear function (e.g., using a piecewise linear approximation through a finite number of predefined points of 8 to 32). fb1 .

[0176] As can be understood, this closed loop operates entirely in the angular domain.

[0177] As mentioned above, the inventors have also discovered another topology that can also reduce or substantially eliminate nonlinearity at very high speeds, such as up to 200 krpm, or even up to 400 or 500 krpm, or 600 or 700 krpm, as will be described below. Figure 6 and Figure 7 As shown.

[0178] Figure 6 Another embodiment of the processing circuit 620 proposed in this invention is shown, which has a signal acquisition circuit 640 and a processing circuit 650. The signal acquisition circuit 640 may be similar to or the same as the signal acquisition circuit of FIG. 1(a) or a variant thereof. However, the processing circuit 650 differs from those described above.

[0179] The processing circuit 650 includes a closed loop formed by: a first sub-circuit 660, the output of which is connected to a filter 632; the output of the filter 632 is connected to a second sub-circuit 670; and the output of the second sub-circuit 670 is fed back to the first sub-circuit 660. More specifically, in Figure 6 In the specific embodiment shown, the processing circuit 650 includes a combiner 631, a phase estimator 627, a filter 632, a nonlinear function block 633, and a phase-to-I / Q converter 634 arranged in a closed loop. The combiner 631 operates in the I / Q domain. The filter 632 and the nonlinear function block 633 operate in the angular domain.

[0180] exist Figure 6 In a specific embodiment,

[0181] A first sub-circuit 660 is arranged to receive the at least one input signal v1, v2 and two feedback signals fbq, fbi. The first sub-circuit 660 includes a combiner 631, followed by a phase estimator 627. The combiner 631 is configured to combine the input signals v1, v2 and the feedback signals fbq, fbi (e.g., by performing a complex multiplication of the complex conjugates of the input signals and the feedback signals). The phase estimator 627 is configured to convert the combined signals into a phase signal θ. 估计 The phase estimator 627 can be an I / Q to phase converter;

[0182] - Filter 632 is a frequency-dependent filter configured to receive and filter the estimated phase signal θ. 估计 And is configured to provide a filtered signal as the output signal θ 校正 ;

[0183] - The second sub-circuit 333 includes a nonlinear function block 633, followed by a phase-to-I / Q converter 634. The nonlinear function block 670 is arranged to receive and modify the filtered signal θ using (e.g., memoryless) nonlinear functions. 校正 For example, a piecewise linear approximation function can be used, which passes through a finite number of predefined points of 8 to 32 that can be stored in non-volatile memory. A phase-to-I / Q converter 634 is configured to receive the modified signal and convert it into at least two component signals, from which two feedback signals fbi and fbq are derived, which are then provided to a combiner 631.

[0184] As can be understood, the closed loop operates partly in the angle domain and partly in the I / Q domain.

[0185] Figure 7Another embodiment of the processing circuit 720 proposed in this invention is shown. This processing circuit 720 has a signal acquisition circuit 740 that is similar to or the same as the signal acquisition circuit in FIG. 5(a), and has the same... Figure 6 The processing circuit 750 is the same as or similar to the processing circuit.

[0186] If the three sensor signals s1, s2, s3 are obtained from an inductive sensor with three receiver coils, these modulated signals are preferably demodulated, digitized and converted into two-phase signals v1, v2 (e.g., by using a Clarke transform), and then provided to the processing circuit 750.

[0187] The principle of this invention is explained for four magnetic position sensor circuits, mainly in Figure 1(a), Figure 5(a), and Figure 6 as well as Figure 7 The invention has been described herein, but is not limited thereto, and many variations are conceived. For example:

[0188] In Figures 1(a) and 5(a), readout circuits 126, 526 provide two signals v1, v2 to phase calculators 127, 527, and the phase calculators 127, 527 calculate (or estimate) the phase or angle based on these signals. However, the invention is also effective if a single sensor is used to measure physical values ​​(e.g., the amplitude of the current to be measured). In this case, the phase calculator can be replaced by another processing block 527 (e.g., an analog or digital scaling block);

[0189] - In Figures 1(a) and 5(a), signals v1 and v2 are digital signals, but this is not absolutely necessary, and the digitization step can also be performed after processing block 527;

[0190] As previously stated, the present invention is also applicable to other systems in which another source (e.g., gravity, light source) and / or another type of sensor (e.g., accelerometer, light sensor) is used. The present invention therefore also discloses:

[0191] - Linear position sensor systems and angular position sensor systems, including position sensor circuits or devices and magnetic sources, such as permanent magnets.

[0192] - Current sensor system, including current sensor circuitry or device, and electrical conductors, such as integrated conductors or external conductors, such as busbars.

[0193] - A proximity sensor system, including sensor circuitry or device, and a conductive target that is movable relative to the sensor device.

Claims

1. A sensor circuit for measuring a physical quantity, the physical quantity having an input phase, the sensor circuit comprising: - a signal acquisition circuit comprising at least one sensor configured for providing at least one input signal related to the physical quantity; - a processing circuit configured for receiving the at least one input signal and for providing an output signal representative of the physical quantity; the processing circuit comprising a closed loop, the closed loop comprising: i) a first sub-circuit arranged for receiving the at least one input signal and at least one feedback signal and comprising a combiner and configured for providing a first signal, the first signal being an estimate of the input phase; ii) a frequency dependent filter configured for receiving and filtering the first signal and for providing a filtered signal or a signal derived therefrom as output signal; and iii) a second sub-circuit configured for receiving the filtered signal and for converting the filtered signal into the at least one feedback signal using a non-linear function; characterized in that the first sub-circuit is configured for receiving two feedback signals; the first sub-circuit further comprises a phase generator configured for providing the first signal, the combiner being followed by the phase generator, wherein the combiner is arranged for receiving and combining the at least one input signal and the two feedback signals and wherein the phase generator is configured for converting the combined signal into the first signal; the second sub-circuit comprises a non-linear functional block arranged for receiving the filtered signal and modifying the filtered signal using the non-linear function and wherein the second sub-circuit further comprises a phase to I / Q converter configured for receiving the modified signal and converting the modified signal into at least two component signals and wherein the two feedback signals are derived from the component signals; the non-linear function is a piece-wise linear approximation function defined by a plurality of parameters determined during a calibration procedure.

2. The sensor circuit of claim 1, characterized in that the piece-wise linear approximation function passes through a finite number of points.

3. The sensor circuit of claim 2, characterized in that the finite number of points is 4 to 32 points.

4. The sensor circuit of claim 2, characterized in that the finite number of points is 8 to 32 points.

5. The sensor circuit of claim 1, characterized in that the signal acquisition circuit comprises at least one magnetic sensor configured for measuring a magnetic field signal associated with the physical quantity to be measured; or wherein the signal acquisition circuit comprises at least two magnetic sensors, wherein each magnetic sensor is configured for measuring a magnetic field associated with the physical quantity to be measured; or wherein the signal acquisition circuit comprises at least three magnetic sensors, wherein each magnetic sensor is configured to measure a magnetic field associated with the physical quantity to be measured.

6. The sensor circuit of claim 1, wherein the output signal is a phase signal indicative of the input phase; and wherein the signal acquisition circuit comprises a plurality of sensors configured to provide a plurality of input signals, each input signal being a function of the input phase; and wherein the plurality of parameters of the piecewise linear approximation function are selected so as to provide the output signal with improved accuracy with respect to the input phase.

7. The sensor circuit of claim 1, characterized in that the processing circuit introduces non-linearities; and wherein the non-linear function block is configured to at least reduce or eliminate the non-linearities introduced by the processing circuit.

8. The sensor circuit of claim 1, characterized in that the plurality of parameters of the piecewise linear approximation function are stored in a non-volatile memory of the sensor circuit.

9. A position sensor system, comprising: - a magnetic source configured to generate a magnetic field having a phase indicative of a mechanical position; and - a sensor circuit according to any one of claims 5 to 7; wherein the second sub-circuit is configured to at least reduce or eliminate errors related to or caused by mechanical non-idealities of the magnetic source positioned outside the sensor circuit.

10. The position sensor system of claim 9, characterized in that the errors comprise higher harmonics.

11. The position sensor system of claim 9, characterized in that the magnetic source is a permanent magnet movable with respect to the sensor circuit, or the sensor circuit is movable with respect to the magnetic source; and wherein the second sub-circuit is configured to at least reduce or eliminate errors related to mechanical mounting aspects.

12. The position sensor system of claim 11, characterized in that the errors comprise higher harmonics.

13. The position sensor system of claim 11, characterized in that the mechanical mounting aspects are selected from the group consisting of: position offset, tilt, eccentricity.

14. The position sensor system of claim 9, comprising a printed circuit board comprising a plurality of coils; and comprising a target movable with respect to the plurality of coils; and comprising the sensor circuit; and wherein the second sub-circuit is configured to at least reduce or eliminate errors related to mechanical mounting aspects of the target.

15. The position sensor system of claim 9, comprising a printed circuit board comprising a plurality of coils; and comprising a target movable with respect to the plurality of coils; and comprising the sensor circuit; and wherein the second sub-circuit is configured to at least reduce or eliminate errors related to layout aspects of the plurality of coils.

16. The position sensor system of claim 9, comprising a printed circuit board comprising a plurality of coils; and comprising a target movable with respect to the plurality of coils; and comprising the sensor circuit; and wherein the second sub-circuit is configured for at least reducing or eliminating errors related to mechanical mounting aspects of the target and to layout aspects of the plurality of coils.

17. The position sensor system of any one of claims 14 to 16, characterized in that the errors comprise higher harmonics.

18. The position sensor system of claim 14 or 16, characterized in that the mechanical mounting aspects are selected from the group consisting of: positional offset, tilt, eccentricity.

19. A current sensor system, comprising: - a current conductor for conducting a current to be measured; and - a sensor circuit according to any one of claims 1 to 8, configured for measuring a magnetic field generated by the current to be measured.

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