Inductive position sensors

Abstract

The present application relates to an inductive position sensor, comprising a microcontroller unit, a mover, and a stator, and further comprising: a signal amplification circuit for amplifying the sensing signal, wherein the sensing signal is a differential signal; a low-frequency filtering circuit, wherein the low-frequency filtering circuit receives the amplified sensing signal and performs high-pass filtering or band-pass filtering on the sensing signal to filter out the low-frequency signal; a demodulation circuit, which receives the sensing signal filtered by the low-frequency filtering circuit and demodulates the sensing signal into a low-frequency demodulation signal; a high-frequency filtering circuit, which receives the demodulated signal and performs low-pass filtering on the demodulated signal to filter out the high-frequency signal; and the microcontroller unit receives the demodulated signal filtered by the high-frequency filtering circuit and converts the demodulated signal into position information.

Description

Technical Field

[0001] The present application relates to the field of sensors, and in particular to an inductive position sensor. Background Art

[0002] Inductive position sensors consist of a stator and a mover, and can be categorized as either rotary or linear displacement inductive position sensors. The stator is equipped with an excitation coil and an induction coil. When a high-frequency AC signal is applied to the excitation coil, an AC magnetic field is generated. This AC field acts on the copper foil on the mover, generating eddy currents. The stator and mover are placed parallel to each other. When the mover rotates relative to the stator or moves horizontally, the eddy currents change. This change is sensed by the induction coil, which in turn changes the mutual inductance between the induction coil and the mover, and the induced signal (induced voltage) output by the induction coil changes accordingly.

[0003] Existing inductive position sensors require a signal decoding device to decode the sensing signal to obtain position information. However, because the induction coil's output signal is typically weak, the demodulated signal must be amplified several dozen times. This significantly amplifies the noise and temperature drift of electronic components like op amps and resistors, increasing the overall signal noise and limiting the effective resolution of the inductive encoder. Existing signal decoding devices also suffer from a limited variety, high cost, limited selection, and amplitude attenuation after demodulation. Summary of the Invention

[0004] In order to obtain a more accurate decoding signal when an inductive position sensor is decoded, the present application proposes a new inductive position sensor.

[0005] The inductive position sensor proposed in this application includes a microcontroller unit, a mover, and a stator. The microcontroller unit transmits an excitation signal to the excitation coil of the stator. When the mover is displaced relative to the stator, the stator remains stationary and the mover moves relative to the stator, or the mover remains stationary and the stator moves relative to the stator, so as to generate and output an induction signal on the induction coil of the stator. Furthermore, it also includes: a signal amplification circuit for amplifying the induction signal, wherein the induction signal is a differential signal; a low-frequency filtering circuit, which receives the amplified induction signal and performs high-pass filtering or band-pass filtering on it to filter out low-frequency signals; a demodulation circuit, which receives the induction signal filtered by the low-frequency filtering circuit and demodulates the induction signal into a low-frequency demodulation signal; a high-frequency filtering circuit, which receives the demodulation signal and performs low-pass filtering on it to filter out high-frequency signals; and the microcontroller unit receives the demodulation signal filtered by the high-frequency filtering circuit and converts the demodulation signal into position information.

[0006] Optionally, the demodulation circuit is a signal sampling circuit, which receives the sensing signal after filtering by the low-frequency filtering circuit and receives a periodic trigger pulse output by the microcontroller unit to trigger sampling of an extreme value of the sensing signal to obtain the demodulated signal, wherein the trigger pulse has a phase delay relative to the sensing signal to align a sampling point with an extreme value point of the sensing signal.

[0007] Optionally, the signal amplification circuit and the low-frequency filtering circuit are integrated into an active filtering circuit.

[0008] Optionally, each time the signal sampling circuit triggers sampling of the sensing signal, the signal sampling circuit maintains the sampled signal value until a trigger pulse of the next cycle triggers sampling of the sensing signal.

[0009] Optionally, the signal amplifying circuit converts the sensing signal, which is a differential signal, into a single-ended signal.

[0010] Optionally, the trigger pulse has the same frequency as the induction signal, and the trigger signal is delayed by 89°-91° in phase relative to the induction signal.

[0011] Optionally, the trigger pulse is delayed by 90° relative to the induction signal.

[0012] Optionally, the differential signal includes a first signal and a second signal, and the trigger pulse includes a first pulse and a second pulse, wherein the first pulse is used to trigger sampling of the first signal, and the second pulse is used to trigger sampling of the second signal.

[0013] Optionally, a switch detection circuit is further included, which receives the sensing signal filtered by the low-frequency filtering circuit and the synchronous square wave output by the micro control unit, and detects the sensing signal into a single-ended detection signal.

[0014] Optionally, the signal sampling circuit receives the detection signal, and samples the detection signal into the demodulated signal based on the trigger pulse.

[0015] Optionally, the trigger pulse has the same frequency as the induction signal, and the trigger signal is phase-delayed by 179°-181° relative to the induction signal.

[0016] Optionally, the trigger pulse is delayed by 180° relative to the induction signal.

[0017] By using the above-mentioned inductive position sensor, under the excitation signal of frequency ω, the induction signal output by the induction coil is first amplified and then subjected to high-pass or band-pass filtering, or processed by an active filter that combines amplification and filtering. This allows the induction signal to pass through essentially losslessly, and effectively suppresses low-frequency and DC signals that are less than the excitation signal frequency ω, especially less than 1 / 10ω.

[0018] Furthermore, the sinusoidal AM signal output by the induction coil is demodulated by a signal sampling circuit. This uses a narrow pulse signal with the same carrier frequency as the sinusoidal AM signal but with a phase delay as the trigger signal to sample the extreme voltages (peaks or valleys) of the AM signal, ensuring accurate acquisition of the extreme voltages. As a result, the inductive position sensor proposed in this application can accurately demodulate the signal carrying the desired position information in most operating environments without attenuating the signal amplitude, thereby obtaining precise position information. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of an inductive position sensor.

[0020] Figure 2 is a schematic diagram of an analog multiplier.

[0021] Figure 3 This is a schematic diagram of a switching synchronous detection circuit.

[0022] Figure 4 is a schematic diagram of an inductive position sensor according to an embodiment of the present application.

[0023] Figure 5 2 is a schematic diagram of signals sampled by a signal sampling circuit according to an embodiment of the present application.

[0024] Figure 6 Schematic diagram of the first embodiment of the inductive position sensor proposed in this application.

[0025] Figure 7 Schematic diagram of the circuit structure of the first embodiment of the inductive position sensor proposed in this application.

[0026] Figure 8 This is a schematic diagram of narrow pulse sampling triggering in the first embodiment of the inductive position sensor proposed in this application.

[0027] Figure 9 Schematic diagram of the second embodiment of the inductive position sensor proposed in this application.

[0028] Figure 10 Schematic diagram of the circuit structure of the second embodiment of the inductive position sensor proposed in this application.

[0029] Figure 11 Schematic diagram of the third embodiment of the inductive position sensor proposed in this application.

[0030] Figure 12 This is a waveform diagram of the third embodiment of the inductive position sensor proposed in this application after detection by the switch synchronous detection circuit.

[0031] Figure 13 Schematic diagram of a fourth embodiment of the inductive position sensor proposed in this application. DETAILED DESCRIPTION

[0032] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. It should be understood that the specific embodiments described herein are only used to illustrate the relevant disclosure and are not intended to limit the disclosure. It should also be noted that for ease of description, only the portions relevant to the relevant disclosure are shown in the drawings.

[0033] First, the terms involved in this application are introduced.

[0034] Carrier frequency: During signal transmission, a lower frequency signal is loaded onto a wave with a fixed higher frequency. This wave is called a carrier wave, and the higher frequency modulated by the lower frequency is called the carrier frequency, or simply carrier frequency.

[0035] Amplitude modulated signal: A signal that adjusts the carrier amplitude according to signal transmission needs but keeps the carrier frequency unchanged. The envelope of the AM signal reflects the change in amplitude and carries the essence of the lower frequency signal.

[0036] Figure 1 Figure 1 is a schematic diagram of an inductive position sensor. Figure 1 As shown, the waveform generator of the microcontroller unit (MCU) generates a high-frequency AC excitation signal (such as an excitation square wave) and inputs it into the excitation coil in the LC resonant circuit of the stator. A corresponding AC magnetic field is generated on the excitation coil, and this AC magnetic field can act on the copper foil on the mover to generate an eddy current magnetic field. When the mover and the stator are relatively displaced, the eddy current magnetic field will change. The induction coil on the stator senses the change in the eddy current magnetic field and outputs an orthogonal amplitude modulated signal (i.e., an induction signal) modulated by the relative displacement of the mover and the stator. The amplitude modulated signal includes a sine (sin) amplitude modulated wave and a cosine (cos) amplitude modulated wave, and both the sine amplitude modulated wave and the cosine amplitude modulated wave are differential signals. During decoding, the sine amplitude modulated wave and the cosine amplitude modulated wave need to be input into the same decoding circuit respectively. Figure 1Inputting the sine amplitude modulated wave and the cosine amplitude modulated wave into one circuit is only for the convenience of explanation, indicating that they are input into the decoding circuit 101 with the same structure, and the sine amplitude modulated wave and the cosine amplitude modulated wave described below refer to this description. The decoding circuit is used to restore the sensing signal to a low-frequency signal without interference that carries the position information. The amplitude modulated signal is directly input into the decoding circuit for decoding to obtain a low-frequency signal carrying the required information to be transmitted, for example, through a traditional synchronous detection circuit, and then the high-frequency signal is filtered out by a low-pass filter. Since the sensing signal output by the induction coil is usually relatively weak, it is necessary to amplify the signal through an amplifier, and then input the amplified signal into the ADC in the MCU for analog-to-digital conversion, and decoded in the MCU to obtain the position information.

[0037] The traditional demodulation circuit of inductive encoder uses analog multiplier (such as Figure 2 As shown), or a switching synchronous detection circuit composed of analog switches (such as Figure 3 As shown). However, analog multipliers are limited in variety, expensive, and selection, and cannot meet all needs. The switching synchronous detection circuit also has defects: if the excitation signal is , then the amplitude modulated signal is , where t is the working time, The principle is: the analog switch LO is selected by a square wave signal with the same frequency ω0 as the excitation signal. When the square wave signal is high, the output is , when the square wave signal is low, the output is . So it can be equivalent to: , where s(t) is:

[0038] .

[0039] Substituting the Fourier series of s(t) into the equation, we can get:

[0040] .

[0041] After filtering Uout to remove the high-frequency components, we can get: From the above derivation formula, it can be seen that the switching synchronous detection circuit has the problem of amplitude attenuation after demodulation, which is only 2 / π at most. In addition, since the filter cannot completely suppress the high-frequency harmonic components, there will be a lot of residual harmonic components.

[0042] In addition, as mentioned above, the sensing signal is usually in the millivolt level and needs to be amplified several dozen times by an operational amplifier after demodulation. However, the operational amplifier's own flicker noise, white noise, and thermal noise of the operational amplifier's peripheral resistors will also be amplified by the operational amplifier. The magnitude of these noises is related to the circuit's operating bandwidth. The larger the bandwidth, the greater the noise. Therefore, the existing decoding circuit will inevitably have the above-mentioned various interference signals, thereby affecting the accuracy of the position information obtained by decoding. Therefore, this application proposes the following new signal decoding device for inductive position sensors.

[0043] First, refer to Figure 4 The schematic diagram of the inductive position sensor is shown to illustrate its working principle.

[0044] like Figure 4 As shown, the inductive position sensor 400 includes a signal amplification circuit 401, a low-frequency filtering circuit 402, a demodulation circuit 403, a high-frequency filtering circuit 404, a microcontroller unit (MCU) 405, a mover 406, and a stator 407. The MCU 405 transmits an excitation signal to the excitation coil in the mover 406. When the mover 406 moves relative to the stator 407, an induction signal is generated and outputted by the induction coil in the stator 407. The excitation signal is preferably a square wave signal. The induction signal includes a sine amplitude modulated signal and a cosine amplitude modulated signal. Both the sine amplitude modulated signal and the cosine amplitude modulated signal are differential signals, as shown in the following equation:

[0045] .

[0046] Among them, u a (t) is a sinusoidal amplitude modulated signal, u b (t) is the cosine amplitude modulation signal, Us is the amplitude of the output amplitude modulation signal, ω is the excitation signal frequency, t is the working time, and θr is the pole logarithm angle between the mover and the stator.

[0047] The frequency of the excitation signal is usually a signal at the Mhz level, and the induced signal generated by the excitation will produce a large attenuation, attenuating into a high-frequency amplitude modulated signal at the millivolt level. When the inductive position sensor 400 is decoded, the induced signal is first amplified by the signal amplification circuit 401, and then the amplified induced signal is input into the low-frequency filtering circuit 402 to filter out various low-frequency noise signals and DC signals that are less than the frequency of the excitation signal, especially the signals less than 1 / 10ω, while ensuring that the signal with a frequency of ω passes through without loss. The low-frequency filtering circuit 402 can be implemented by a high-pass filter or a suitable band-pass filter. Moreover, in actual circuit implementation, the signal amplification circuit 401 and the low-frequency filtering circuit 402 can also be integrated into one, and implemented by an active filtering circuit. It can be understood by those skilled in the art that, in the case of Figure 1 In the conventional inductive position sensor shown, since the low-frequency noise is only relatively low, its frequency is still within the bandwidth of the signal used for decoding. Therefore, to ensure the desired signal passes, the low-pass filter's cutoff frequency cannot be set low enough to filter out the low-frequency noise, and thus low-frequency filtering is not performed before demodulation. Therefore, conventional inductive position sensors first demodulate the low-frequency envelope signal through synchronous detection, then low-pass filter the demodulated signal to filter out high-frequency noise, and then amplify the signal. As can be seen, low-frequency filtering is no longer possible after the low-frequency envelope signal is demodulated. Therefore, in conventional inductive position sensors, noise is also amplified after signal amplification, reducing sensor accuracy. However, the present invention shifts the spectrum of the desired signal to a higher frequency band, enabling the signal to be amplified and low-frequency noise filtered out by pre-installing a low-frequency filtering circuit. Since demodulation is not performed, only the low-frequency noise is filtered out, while the high-frequency sensing signal is retained. Demodulation and subsequent processing are then performed, significantly improving the signal-to-noise ratio.

[0048] Then, the sensing signal after filtering out the low-frequency interference is input into the demodulation circuit 403 for demodulation to restore the low-frequency signal carrying the position information. Figure 4 As shown, the demodulation circuit 403 can preferably be a signal sampling circuit that simultaneously receives periodic trigger pulses output by the MCU 405. These trigger pulses trigger the sampling of the sensing signal, thereby implementing a synchronous detection function, sampling the high-frequency sensing signal into the desired low-frequency sampling signal (i.e., the demodulated signal) that carries the position information. At this stage, since the desired sampling signal is a low-frequency signal, the sampling signal needs to be input into a high-frequency filtering circuit 404 to filter out high-frequency noise, thereby improving the resolution of the inductive position sensor 400. The high-frequency filtering circuit 404 can be implemented as a low-pass filter. Finally, the sampling signal, after filtering out high-frequency noise, is input into the MCU 405, where it can be decoded into the position information. Alternatively, the demodulation circuit can be a conventional synchronous switch detection demodulation circuit or an analog multiplier demodulation circuit.

[0049] The signal sampling circuit in the present application adopts a synchronous extreme value sampling method. Since the induction signal is an amplitude modulated signal in the form of a sinusoidal signal (including the aforementioned sinusoidal amplitude modulated signal and cosine amplitude modulated signal), a narrow pulse signal with the same carrier frequency as the amplitude modulated signal but with a phase delay is used as the trigger signal to ensure that the sampled value obtained each time is the extreme value of the high-frequency sinusoidal induction signal (i.e., the peak signal value or the trough signal value). Whenever the sampling of the induction signal is triggered, the sampled signal value will be maintained until the trigger pulse of the next sampling period triggers the sampling. Therefore, the sampling value in each sampling period is the extreme value of the induction signal in the corresponding time period, so that the detection can obtain a step-type sampling signal that is close to the envelope of the induction signal. As shown Figure 5 As shown, the first curve 501 is the envelope carrying the position information, and the second curve 502 is the step-type sampling signal, wherein each step corresponds to an extreme value of the sinusoidal amplitude modulation signal.

[0050] The higher the frequency of the sensing signal, the shorter the period of the trigger pulse, and the higher the sampling rate, the closer the resulting step-shaped sampling signal is to the actual low-frequency sinusoidal envelope. Therefore, when the carrier frequency of the sensing signal is in the MHz range, the difference is negligible. Furthermore, when the trigger pulse signal and the amplitude modulated signal have the same frequency and a phase lag of approximately 90° (for example, within the range of 89°-91°, with 90° being optimal), amplitude attenuation of the demodulated signal can be avoided and high-frequency harmonic components can be suppressed. In summary, with this signal sampling circuit, the resulting sampled signal can be considered a low-frequency envelope signal that carries position information.

[0051] Based on the above working principles, this application proposes a variety of different implementation methods of inductive position sensors.

[0052] Figure 6 This is a schematic diagram of a first embodiment of the inductive position sensor proposed in this application.

[0053] In the first embodiment, the signal amplification circuit utilizes a first differential-to-single-ended amplifier circuit 601, which directly converts the differential signal into a single-ended signal for amplification before outputting it to the first low-frequency filter circuit 602. The differential-to-single-ended amplifier circuit can be implemented using a differential amplifier, or by integrating the differential-to-single-ended amplifier circuit and the first low-frequency filter circuit into a first-order active high-pass filter. In this embodiment, the demodulation circuit is a first signal sampling circuit 603, whose trigger pulse phase lags the sensing signal by 90°, enabling precise sampling of each peak signal in the sensing signal. Furthermore, the ADC built into the MCU can be used for analog-to-digital conversion, or, as needed, the low-pass filtered signal can be first input into an external, more precise ADC device for analog-to-digital conversion, and then the digital signal can be input into the MCU for position information calculation. Due to the use of synchronous extreme value sampling, the present application achieves a higher bandwidth for the required low-pass filter compared to conventional switching synchronous detection circuits. The calculation method can include any suitable method, such as the inverse tangent method or a phase-locked loop (PLL).

[0054] Figure 7 Schematic diagram of the circuit structure of the first embodiment. Among them, capacitor C19, resistor R15, resistor R13, and op amp U13-B constitute a first-order active filter circuit, and analog switch U7, capacitor C5, and op amp U9-B constitute a signal sampling circuit. The synchronous narrow pulse PULSE is output from the I / O port of the MCU, and its frequency is the same as the carrier frequency of the amplitude modulated signal SIGNAl output by the induction coil, and its phase lags the carrier frequency of the amplitude modulated signal by about 90°, that is, the rising edge of the PULSE is aligned with the extreme point of SIGNAl, as shown in FIG. Figure 8 The schematic diagram of the medium-narrow pulse sampling trigger is shown below. When PULSE is high, analog switch U7 closes. After capacitor C5 charges to near the extreme voltage of the SIGN1 signal, PULSE becomes low, analog switch U7 opens, and the voltage on capacitor C5 remains. Op amp U9-B maintains the current SIGN1 signal extreme voltage output until the next switching cycle (trigger pulse cycle) arrives, at which point the new extreme voltage is updated.

[0055] Figure 9 This is a schematic diagram of a second embodiment of the inductive position sensor proposed in this application.

[0056] In the second embodiment, the signal amplification circuit utilizes a differential signal amplification circuit 901, which separately amplifies the first signal (+ signal) and the second signal (- signal) within the differential signal (e.g., the + and - signals of a sine amplitude modulated wave, or the + and - signals of a cosine amplitude modulated wave). Unlike the first embodiment, which converts the differential signal into a single-ended signal for amplification, the amplified first and second signals pass through a second low-frequency filtering circuit 902 (a high-pass filter or a band-pass filter) and are then input into a second signal sampling circuit 903 for sampling. Since two signals are present simultaneously, two trigger signals are also required: a first pulse triggers the sampling of the first signal, and a second pulse triggers the sampling of the second signal. Alternatively, the differential signal amplification circuit and the second low-frequency filtering circuit can be integrated into a differential active high-pass filter or an active band-pass filter.

[0057] Figure 10 This is a schematic diagram of the circuit structure of the second embodiment. Op amps U1-B and U2-B, resistors R2, R3, R6, and capacitor C4 form a differential high-pass active filter, while analog switches U14 and U15, op amp U17-B, and capacitor C11 form a differential signal sampling circuit. The first signal SIGNAl+ and the second signal SIGNAl- are differential signals from the induction coil, and the first pulse PULSE1 and the second pulse PULSE2 are narrow pulses output from the I / O port of the MCU. The frequencies of PULSE1, PULSE2, SIGNAl+, and SIGNAl- are the same. PULSE1 lags 90° relative to the carrier frequency of SIGNAl+, and PULSE2 lags 180° relative to PULSE1. It is easy to understand that since two signals need to be sampled simultaneously, the number of sampling points in the second embodiment is twice that of the first embodiment.

[0058] Compared with the first embodiment, the signal in the second embodiment is more accurate.

[0059] Figure 11 This is a schematic diagram of a third embodiment of the inductive position sensor proposed in this application.

[0060] Compared with the second embodiment, the third embodiment performs a primary detection through a switch synchronous detection circuit 112 after high-pass filtering by the third low-frequency filter circuit 111, so that two peaks or valleys appear in one original carrier frequency cycle to convert the differential signal into a single-ended signal. Figure 12Figure 1 is a schematic diagram of the waveform after switching synchronous detection. It can be seen that the detected signal still contains high-frequency components (i.e., the shaded portion). Therefore, the detected signal still needs to be input into the third signal sampling circuit 113 for sampling. This switching synchronous detection circuit is functionally equivalent to a single-phase bridge rectifier circuit. However, because the amplitude modulated wave is a DSB signal, the negative half-axis of the carrier is also rectified to the positive half-axis during the positive half-cycle of the modulation envelope, and the positive half-axis of the carrier is rectified to the negative half-axis during the negative half-cycle of the modulation envelope, resulting in two extreme values ​​within the original carrier cycle. Therefore, the trigger pulse frequency should be twice the frequency of the sensing signal, resulting in twice the number of sampling points as in the first embodiment. The phase lag should be approximately 180° (e.g., within the range of 179°-181°, with 180° being optimal) relative to the sensing signal to ensure that all extreme values ​​are sampled, thereby improving signal accuracy.

[0061] Figure 13 This is a schematic diagram of a fourth embodiment of the inductive position sensor proposed in this application.

[0062] In the fourth embodiment, the signal sampling circuit and high-frequency filtering circuit are integrated into the MCU 131. The differential signal is directly input into the MCU 131 after passing through the fourth differential-to-single-ended amplifier circuit 132 and the fourth low-frequency filtering circuit 133 for further processing. While the fourth embodiment has a simple structure, it requires a high-performance MCU to ensure high accuracy in signal sampling and low-pass filtering.

[0063] The above is an explanation of the embodiments of the present application by specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this embodiment. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other unless there is a conflict.

[0064] Furthermore, various operations will be described as multiple discrete operations in a manner that is most helpful in understanding the illustrative embodiments; however, the order of description should not be construed as implying that these operations are necessarily order dependent. In particular, these operations do not need to be performed in the order presented.

[0065] Unless the context dictates otherwise, the terms "comprising," "having," and "including" are synonymous. The phrase "A / B" means "A or B." The phrase "A and / or B" means "(A and B) or (A or B)."

[0066] As used herein, the term “module” or “unit” may refer to, be or include: an application specific integrated circuit (ASIC), an electronic circuit, a (shared, dedicated or group) processor and / or memory that executes one or more software or firmware programs, a combinational logic circuit and / or other suitable components that provide the described functionality.

[0067] In the accompanying drawings, some structural or method features are shown in a specific arrangement and / or order. However, it should be understood that such specific arrangement and / or order may not be required. In some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. In addition, the inclusion of structural or method features in a particular figure does not imply that such features are required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0068] It should be understood that although the terms "first," "second," and the like may be used herein to describe various elements or data, these elements or data should not be limited by these terms. These terms are used only to distinguish one feature from another. For example, a first feature may be referred to as a second feature, and similarly, a second feature may be referred to as a first feature without departing from the scope of the exemplary embodiments.

[0069] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0070] While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1. An inductive position sensor comprising a microcontroller, a mover, and a stator, wherein the microcontroller transmits an excitation signal to an excitation coil of the stator. When the mover is displaced relative to the stator, the stator remains stationary while the mover moves relative to the stator, or the mover remains stationary while the stator moves relative to the stator, thereby generating and outputting an induction signal on the induction coil of the stator. The sensor is characterized in that: Also includes: a signal amplifying circuit, configured to amplify the sensing signal, wherein the sensing signal is a differential signal; a low-frequency filtering circuit, which receives the amplified sensing signal and performs high-pass filtering or band-pass filtering on the amplified sensing signal to filter out low-frequency signals; a switch detection circuit, the switch detection circuit receiving the sensing signal filtered by the low-frequency filtering circuit and the synchronous square wave output by the micro control unit, and detecting the sensing signal into a single-ended detection signal; A demodulation circuit receives the detection signal and demodulates the detection signal into a low-frequency demodulation signal; a high-frequency filtering circuit, receiving the demodulated signal and performing a low-pass filter on the demodulated signal to filter out high-frequency signals; The micro control unit receives the demodulated signal filtered by the high-frequency filtering circuit to convert the demodulated signal into position information.

2. The inductive position sensor according to claim 1, wherein: The demodulation circuit is a signal sampling circuit that receives the detection signal and the periodic trigger pulses output by the microcontroller unit to trigger sampling of the extreme values ​​of the detection signal to obtain the demodulated signal. The trigger pulse is phase delayed relative to the sensing signal to align the sampling point with the extreme value of the sensing signal.

3. The inductive position sensor according to claim 2, wherein: The signal amplifying circuit and the low-frequency filtering circuit are integrated into an active filtering circuit.

4. The inductive position sensor according to claim 2, wherein: Each time the signal sampling circuit triggers sampling of the sensing signal, the sampled signal value is maintained until a trigger signal of the next cycle triggers sampling of the sensing signal.

5. The inductive position sensor according to claim 4, wherein: The frequency of the trigger pulse is twice the frequency of the induction signal, and the phase of the trigger pulse is delayed by 179°-181° relative to the induction signal.

6. The inductive position sensor according to claim 5, characterized in that The trigger pulse is delayed by 180° relative to the sensing signal.

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