Magnetic flux sensor signal measuring circuit and peak holder

Abstract

The utility model provides a magnetic flux sensor signal measuring circuit and a peak holder. The magnetic flux sensor signal measuring circuit comprises a magnetic flux sensor. The signal input end of the amplifying and filtering assembly is connected with the signal output end of the magnetic flux sensor; the signal input end of the buffer conversion assembly is connected with the signal output end of the amplifying and filtering assembly; the signal input end of the control assembly is connected with the signal output end of the amplifying and filtering assembly and the signal output end of the buffering and converting assembly. According to the utility model, peak value tracking is carried out on a voltage signal through the buffer conversion assembly, so that a post-stage circuit has sufficient time for sampling and calculation, a high-precision integral voltage value is obtained, an accurate force value of a measured component is further obtained, and a sampling starting signal is generated through the control assembly, so that the measurement precision is improved. Compared with an existing mode of discretized sampling of the integral voltage signal, the problem that the peak value of the integral voltage signal is insufficient in tracking is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of signal circuits, in particular to a magnetic flux sensor signal measurement circuit and a peak value holder. Background Art

[0002] The magnetic flux acquisition device measures the signal by integrating the exponential pulse signal output by the induction coil of the magnetic flux sensor to obtain the integrated voltage value. This value reflects the change in the magnetic permeability of the current load-bearing component. By calibrating the load-bearing component, the relationship between the magnetic permeability of the measured load-bearing component and the actual force value can be obtained.

[0003] In the prior art, in the current magnetic flux sensor signal conditioning circuit, the integrated voltage value output by the integration circuit is measured by high-speed sampling through an analog-to-digital converter to obtain a discrete digital integrated signal, such as Figure 1 As shown, the maximum value selection algorithm is then used to obtain the integrated voltage value. Since the integral signal is a slowly varying signal, and the integral signal decays rapidly after the input exponential pulse signal ends, if the sampling rate is not set properly, the tracking of the maximum value of the integral signal will be lost. At the same time, due to the specifications of different magnetic flux sensors, the time parameters of the input exponential pulse signal will also be different, resulting in different holding times of the integral voltage signal after passing through the integration circuit. This will cause measurement errors through digital sampling, and the measurement errors will also be different for sensors of different specifications. In addition, when performing algorithmic processing on the discrete integral voltage signal, due to insufficient number of peak point samples, such as Figure 2 As shown, there will be some samples below the peak value involved in the calculation, so the data after the mean calculation will also have errors. Utility Model Content

[0004] Based on this, the purpose of the utility model is to provide a magnetic flux sensor signal measurement circuit and a peak holder to at least solve the above-mentioned deficiencies in the prior art.

[0005] In a first aspect, the utility model provides a magnetic flux sensor signal measurement circuit, comprising:

[0006] Magnetic flux sensor;

[0007] an amplifying and filtering component, wherein a signal input end of the amplifying and filtering component is connected to a signal output end of the magnetic flux sensor;

[0008] A buffer conversion component, wherein a signal input end of the buffer conversion component is connected to a signal output end of the amplifying and filtering component;

[0009] A control component, wherein a signal input end of the control component is respectively connected to a signal output end of the amplifying and filtering component and a signal output end of the buffer conversion component;

[0010] Among them, the amplification and filtering component is used to amplify and filter the voltage signal sensed by the magnetic flux sensor, the buffer conversion component is used to track the peak value of the amplified and filtered voltage signal and perform buffer conversion, and the control component is used to control the sampling rate and sampling duration in the buffer conversion component, and compare the amplified and filtered voltage signal with a preset voltage to generate a sampling start signal and transmit it to the buffer conversion component.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: by performing peak tracking of the voltage signal through a buffer conversion component, the maximum value of the integral signal that originally attenuated and changed is maintained and continued for a period of time, so that the subsequent circuit has sufficient time to sample and calculate, and obtain a high-precision integral voltage value, and then obtain an accurate force value of the measured component, and by generating a sampling start signal through a control component, compared with the prior method of discrete sampling of the integral voltage signal, the problem of insufficient peak tracking of the integral voltage signal is solved.

[0012] Furthermore, the amplification and filtering component includes an integration circuit, a signal amplification circuit and a low-pass filter. The signal input end of the integration circuit is connected to the signal output end of the magnetic flux sensor, the signal input end of the signal amplification circuit is connected to the signal output end of the integration circuit, the input end of the low-pass filter is connected to the output end of the signal amplification circuit, and the signal output end of the low-pass filter is respectively connected to the signal input end of the buffer conversion component and the signal input end of the hysteresis voltage comparator.

[0013] Furthermore, the buffer conversion component includes a peak holding circuit, a signal buffer and an analog-to-digital converter, the signal input end of the peak holding circuit is respectively connected to the signal output end of the amplifying and filtering component, the signal input end of the signal buffer is connected to the signal output end of the peak holder, the signal output end of the signal buffer is connected to the signal input end of the analog-to-digital converter, and the signal output end of the analog-to-digital converter is connected to the signal input end of the microcontroller.

[0014] Furthermore, the microcontroller is used to control the sampling rate and sampling duration of the analog-to-digital converter.

[0015] Furthermore, the control component includes a microcontroller and a hysteresis voltage comparator, the signal output end of the hysteresis voltage comparator is connected to the input end of the microcontroller, and the signal output end of the buffer conversion component is connected to the signal input end of the microcontroller.

[0016] Furthermore, the signal output end of the amplifying and filtering component is connected to the signal input end of the hysteresis voltage comparator, and the signal output end of the microcontroller is connected to the signal input end of the buffer conversion component.

[0017] Furthermore, the voltage signal sensed by the magnetic flux sensor is an exponential pulse signal.

[0018] In a second aspect, the utility model further provides a peak holder, comprising the above-mentioned magnetic flux sensor signal measurement circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the waveform of the sensing signal after passing through the integration circuit;

[0020] Figure 2 is the integrated voltage signal after discrete sampling;

[0021] Figure 3 It is a structural schematic diagram of a magnetic flux sensor signal measurement circuit in an embodiment of the utility model;

[0022] Figure 4 It is a schematic diagram of the magnetic flux sensor sensing signal before passing through the integration circuit in the embodiment of the utility model;

[0023] Figure 5 It is a schematic diagram of an integrated signal after passing through a peak holding circuit in an embodiment of the utility model;

[0024] Figure 6 is a start signal output by the hysteresis voltage comparator in the embodiment of the utility model;

[0025] Figure 7 It is a schematic diagram of the structure of the integration circuit, the signal amplification circuit and the low-pass filter in the embodiment of the utility model;

[0026] Figure 8 It is a schematic diagram of the structure of the peak holding circuit in the embodiment of the utility model.

[0027] Description of main component symbols:

[0028] 1. Magnetic flux sensor;

[0029] 20. Amplification and filtering components; 2. Integral circuit; 3. Signal amplification circuit; 4. Low-pass filter;

[0030] 30. Buffer conversion component; 5. Peak hold circuit; 6. Signal buffer; 7. Analog-to-digital converter;

[0031] 40. Control component; 8. Microcontroller; 9. Hysteresis voltage comparator.

[0032] The following specific implementation manner will further illustrate the present utility model in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0034] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0036] See also Figure 3 , shown is a signal measurement circuit of a magnetic flux sensor 1 in an embodiment of the utility model, including a magnetic flux sensor 1, an amplifying and filtering component 20, a buffer conversion component 30 and a control component 40.

[0037] The signal input end of the amplifying and filtering component 20 is connected to the signal output end of the magnetic flux sensor 1, the signal input end of the buffer conversion component 30 is connected to the signal output end of the amplifying and filtering component 20, and the signal input end of the control component 40 is respectively connected to the signal output end of the amplifying and filtering component 20 and the signal output end of the buffer conversion component 30, wherein the amplifying and filtering component 20 is used to amplify and filter the voltage signal sensed by the magnetic flux sensor 1, the buffer conversion component 30 is used to perform peak tracking and buffer conversion on the amplified and filtered voltage signal, and the control component 40 is used to control the sampling rate and sampling duration in the buffer conversion component 30, and compare the amplified and filtered voltage signal with a preset voltage to generate a sampling start signal and transmit it to the buffer conversion component 30.

[0038] Wherein, the voltage signal induced by the magnetic flux sensor 1 is an exponential pulse signal.

[0039] Specifically, in this embodiment, the amplifying and filtering component 20 includes an integrating circuit 2, a signal amplifying circuit 3 and a low-pass filter 4. The signal input end of the integrating circuit 2 is connected to the signal output end of the magnetic flux sensor 1, the signal input end of the signal amplifying circuit 3 is connected to the signal output end of the integrating circuit 2, the input end of the low-pass filter 4 is connected to the output end of the signal amplifying circuit 3, and the signal output end of the low-pass filter 4 is respectively connected to the signal input end of the buffer conversion component 30 and the signal input end of the hysteresis voltage comparator 9. The buffer conversion component 30 includes a peak holding circuit 5, a signal buffer 6 and an analog-to-digital converter 7. The signal input end of the peak holding circuit 5 is respectively connected to the amplifying and filtering component The signal output end of the signal buffer 20 and the signal input end of the signal buffer 6 are connected to the signal output end of the peak holder, the signal output end of the signal buffer 6 is connected to the signal input end of the analog-to-digital converter 7, the signal output end of the analog-to-digital converter 7 is connected to the signal input end of the microcontroller 8, the control component 40 includes the microcontroller 8 and the hysteresis voltage comparator 9, the signal output end of the hysteresis voltage comparator 9 is connected to the input end of the microcontroller 8, the signal output end of the buffer conversion component 30 is connected to the signal input end of the microcontroller, the signal output end of the amplifying and filtering component 20 is connected to the signal input end of the hysteresis voltage comparator 9, and the signal output end of the microcontroller is connected to the signal input end of the buffer conversion component 30. The microcontroller 8 is used to control the sampling rate and sampling duration of the analog-to-digital converter 7.

[0040] In a specific implementation, the induction signal of the magnetic flux sensor 1 is an exponential pulse signal, such as Figure 4 As shown, after passing through the integration circuit 2, the signal becomes the charging signal of the integration circuit 2, such as Figure 2 As shown, Figure 2 When the signal in accumulates to the highest point Um, it means that the input exponential pulse signal ends and the signal integration process ends. The highest point of the integrated signal is the voltage value that needs to be accurately measured.

[0041] The signal output by the integration circuit 2 needs to be conditioned after passing through the signal amplification and phase adjustment circuit; for example, the integration voltage is set to a reasonable gain to adapt to the dynamic range of the analog-to-digital converter 7; since the integration circuit 2 is generally configured with an inverting output, the signal amplification circuit 3 needs to invert the integration signal again to adjust the signal to a positive unipolar signal before inputting the analog-to-digital converter 7;

[0042] After the integrated signal passes through the signal amplification circuit 3, it needs to pass through the low-pass filter 4 to filter out noise and interference outside the signal bandwidth and optimize the signal quality. After the integrated signal passes through the low-pass filter 4, it will enter the core part of this patent, that is, the peak holding circuit 5, which can track the peak value Um of the signal and maintain it for a certain time t, such as Figure 5 As shown. In this way, the signal maintaining the peak value will have enough time for the subsequent analog-to-digital conversion to perform sufficient sampling, and then perform algorithms such as average filtering to obtain an accurate integrated voltage value. The integrated signal after passing through the peak holding circuit 5 passes through the voltage buffer to improve the driving ability of the signal and ensure that no loss occurs when entering the analog-to-digital converter 7. The analog-to-digital converter 7 converts the analog integrated voltage signal at a certain sampling rate to obtain a discrete digital sample. The microcontroller 8 obtains a set of discrete integrated voltage sample values ​​by controlling the sampling rate and sampling duration of the analog-to-digital converter 7. The data is then optimized and filtered by the algorithm, and the mean is calculated to obtain an accurate integrated voltage value. The hysteresis voltage comparator 9 can obtain a start signal for the integrated voltage sampling by setting a suitable reference voltage Ua and comparing it with the integrated voltage signal before entering the peak holder. The signal is provided to the microcontroller 8 to initialize and start sampling the analog-to-digital converter 7. Specifically, Figure 6 shown.

[0043] Further, such as Figure 7 As shown, it is a schematic diagram of the structure of the integration circuit 2, the signal amplification circuit 3 and the low-pass filter 4, R60 is the integration input resistor, C65 is the integration capacitor, and R59 is the feedback resistor. The output of the integration circuit 2 is: Vo = -(1 / RC)*∫Vi*dt, where R is R60 and C is C65. The RC time constant needs to be more than 10 times the duration of the input signal to ensure that the integration circuit 2 does not saturate. Generally, the duration of the sensing signal of the magnetic flux sensor 1 is within 10ms, so the RC time constant is generally set to more than 100ms. R59 is a feedback resistor, which is used to suppress the DC gain of the circuit and prevent the integration circuit 2 from saturating due to the parameters of the circuit itself, such as the offset voltage and bias current of the operational amplifier. The selection of R59 is generally based on the DC gain to ensure that the circuit is saturated, and at the same time, the transition frequency 1 / 2πR59*C65 is reduced as much as possible to increase the lower limit of the working range of the integration circuit 2. The operational amplifier of the integration circuit 2 needs to select the input process of JFET or CMOS to ensure the low bias current on the integration accuracy. The integral capacitor C65 is a polystyrene capacitor, which has a smaller dielectric absorption rate and leakage current;

[0044] The signal amplifier circuit 3 is an inverting gain configuration. Since the signal output by the integration circuit 2 is inverted, it is necessary to convert the integrated voltage into a positive polarity signal after one inversion: Vout = -(Rf / Ra)*[-(1 / RC)*∫Vi*dt] = (Rf / Ra)*[(1 / RC)*∫Vi*dt]. The gain A of this circuit is -R62 / R61. It is necessary to select a suitable gain according to the power rail and the dynamic range of the analog-to-digital converter 7.

[0045] The low-pass filter 4 adopts a unit-gain two-stage active low-pass filter 4 of SK topology structure. The passband cutoff frequency of the filter can be guaranteed to be higher than the upper limit of the integral signal bandwidth.

[0046] See also Figure 8 , the diode D49 and the operational amplifier U91A in the peak holding circuit 5 form an ideal diode circuit to eliminate the error caused by the diode charging voltage drop. D48 plays a clamping role when re-establishing the peak value of the input signal to prevent the circuit from responding too slowly when negative saturation occurs. Q1 is a JFET. Here, the source and drain of the JFET are connected together, and Q1 is used as a diode because the reverse leakage current of the JFET is much smaller than that of an ordinary diode. The voltage on the capacitor C118 tracks the voltage (peak value) of the input signal. The C118 capacitor is also the same as the integral capacitor in the integral circuit 2, and a polystyrene capacitor is selected to ensure the peak tracking performance. R129, R130, R131, U92 and the capacitor C118 form a capacitor voltage clearing circuit, because after measuring an integral voltage signal, the charge stored on the capacitor C118 needs to be discharged and cleared to avoid affecting the next measurement. When performing the clearing operation, the microcontroller 8 enables the XF pin, U92 is turned on, and C118 is cleared through R129.

[0047] It is worth noting that, in the present embodiment, the signal buffer 6 is mainly used to improve the driving capability of the analog-to-digital converter 7 and improve the DC accuracy, and a voltage follower is generally used to achieve signal buffering; 6. Since the analog-to-digital converter 7 uses the peak holding circuit 5, the requirements for the sampling rate of the analog-to-digital converter 7 are greatly reduced, as long as enough samples can be sampled within the integral signal holding period.

[0048] It should be explained that the microcontroller 8 mainly reads and configures the work of the analog-to-digital converter 7, executes the data algorithm on the data of the analog-to-digital converter 7, and obtains a more accurate integrated voltage value. At the same time, the start signal of the hysteresis voltage comparator 9 is monitored. When the start signal is detected, the microcontroller 8 starts the analog-to-digital converter 7 to sample and read the data. After the acquisition is completed, the microcontroller 8 enables the XF signal and clears the charge of the capacitor C118. The hysteresis voltage comparator 9 is mainly used to capture the start value Ua of the integrated voltage signal, and then outputs a logic signal to the microcontroller 8 to start data sampling.

[0049] In addition, the utility model also provides a peak holder, including a magnetic flux sensor 1 signal measurement circuit.

[0050] In summary, the magnetic flux sensor 1 signal measurement circuit in the above embodiment of the utility model can maintain the maximum value of the original attenuated integral signal for a period of time, so that the subsequent circuit has sufficient time to sample and calculate, obtain a high-precision integral voltage value, and then obtain an accurate force value of the measured component. Compared with the existing method of discrete sampling of the integral voltage signal, the problem of insufficient tracking of the integral voltage signal peak is solved.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0052] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A magnetic flux sensor signal measurement circuit, characterized in that: include: Magnetic flux sensor; an amplifying and filtering component, wherein a signal input end of the amplifying and filtering component is connected to a signal output end of the magnetic flux sensor; A buffer conversion component, wherein a signal input end of the buffer conversion component is connected to a signal output end of the amplifying and filtering component; A control component, wherein a signal input end of the control component is respectively connected to a signal output end of the amplifying and filtering component and a signal output end of the buffer conversion component; The control component includes a microcontroller and a hysteresis voltage comparator, the signal output end of the hysteresis voltage comparator is connected to the input end of the microcontroller, and the signal output end of the buffer conversion component is connected to the signal input end of the microcontroller; The buffer conversion component comprises a peak holding circuit, a signal buffer and an analog-to-digital converter, wherein the signal input end of the peak holding circuit is respectively connected to the signal output end of the amplifying and filtering component, and the signal input end of the signal buffer is connected to the signal output end of the peak holding circuit, the signal output end of the signal buffer is connected to the signal input end of the analog-to-digital converter, and the signal output end of the analog-to-digital converter is connected to the signal input end of the control component; Wherein, the microcontroller is used to control the analog-to-digital converter, and the hysteresis voltage comparator is used to obtain a start signal for sampling the integrated voltage, and provide the start signal to the microcontroller to initialize the analog-to-digital converter and start sampling; Among them, the amplification and filtering component is used to amplify and filter the voltage signal sensed by the magnetic flux sensor, the buffer conversion component is used to track the peak value of the amplified and filtered voltage signal and perform buffer conversion, and the control component is used to control the sampling rate and sampling duration in the buffer conversion component, and compare the amplified and filtered voltage signal with a preset voltage to generate a sampling start signal and transmit it to the buffer conversion component.

2. The magnetic flux sensor signal measurement circuit according to claim 1, characterized in that: The amplifying and filtering component includes an integrating circuit, a signal amplifying circuit and a low-pass filter. The signal input end of the integrating circuit is connected to the signal output end of the magnetic flux sensor, the signal input end of the signal amplifying circuit is connected to the signal output end of the integrating circuit, the input end of the low-pass filter is connected to the output end of the signal amplifying circuit, and the signal output end of the low-pass filter is respectively connected to the signal input end of the buffer conversion component and the signal input end of the control component.

3. The magnetic flux sensor signal measurement circuit according to claim 1, characterized in that: The microcontroller is used to control the sampling rate and sampling duration of the analog-to-digital converter.

4. The magnetic flux sensor signal measurement circuit according to claim 1, characterized in that: The signal output end of the amplifying and filtering component is connected to the signal input end of the hysteresis voltage comparator, and the signal output end of the microcontroller is connected to the signal input end of the buffer conversion component.

5. The magnetic flux sensor signal measurement circuit according to claim 1, characterized in that: The voltage signal induced by the magnetic flux sensor is an exponential pulse signal.

6. A peak holder, characterized in that: The magnetic flux sensor signal measurement circuit comprises the magnetic flux sensor signal measurement circuit according to any one of claims 1 to 5.

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