Magnetoelectric speed sensor signal acquisition circuit and fault diagnosis method

Abstract

The invention discloses a magnetoelectric speed sensor signal acquisition circuit and a fault diagnosis method. The magnetoelectric speed sensor signal acquisition circuit comprises a low-pass filter circuit, an amplitude limiting circuit, a lifting and adjustable amplifying circuit, a self-adaptive peak detection circuit, a threshold adjusting circuit, an in-phase hysteresis comparison circuit, a fault detection circuit and a single chip microcomputer module. The lifting and adjustable amplifying circuit is used for lifting the peak value of the signal subjected to amplitude limiting in a bias manner and amplifying the signal by a certain multiple; the self-adaptive peak detection circuit is used for detecting and acquiring a peak voltage; the threshold adjusting circuit is used for dividing the peak voltage; the in-phase hysteresis comparison circuit is used for comparing two paths of input signals and outputting a square wave signal to the single chip microcomputer module to obtain a signal frequency value; the single-chip microcomputer module is used for controlling switching of amplification times based on the signal frequency value and controlling fault detection of the magnetoelectric speed sensor. The amplification factor is automatically switched based on the signal intensity, the threshold voltage of the comparator is dynamically adjusted according to the signal peak value, and the detection reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor detection, and in particular to a magnetoelectric speed sensor signal acquisition circuit and a fault diagnosis method. Background Art

[0002] The magnetoelectric speed sensor is one of the most important control parameters of the gearbox. Its operating mechanism is that the periodic approach or separation between the gear teeth and the sensing end face causes the magnetic resistance of the electromagnetic circuit to change, causing the magnetic flux inside the coil to increase or decrease, thereby generating a quasi-sine wave periodic voltage signal. The amplitude of this signal is positively correlated with the speed, while the frequency response is linearly related to the speed. That is, the signal amplitude and frequency parameters increase synchronously when the mechanical speed increases. However, this type of sensor is integrated into the strong electromagnetic environment of the vehicle and is susceptible to coupling of multiple sources of electromagnetic interference, resulting in interference with the output signal. Especially under extreme operating conditions, small signals in the low-frequency band are easily drowned out by noise, and signals in the high-frequency band are prone to overload distortion, which ultimately leads to abnormal phenomena such as pulse waveform distortion or data acquisition failure.

[0003] The processing circuits of existing magnetoelectric speed sensors typically only use a "limiting + amplification" method, but this cannot take into account differences in signal strength when the speed changes. In particular, at low speeds, the signal is weak and easily overwhelmed by noise, resulting in reduced detection accuracy. At the same time, existing comparator circuits mostly use a fixed threshold voltage. When the signal amplitude fluctuates due to operating conditions, the mismatch between the threshold and the signal will cause false triggering. In addition, there is a lack of a diagnostic mechanism for short-circuit and open-circuit faults at the sensor signal input end, resulting in the system's inability to detect in a timely manner, which may cause misjudgment or controller failure.

[0004] Existing sensor signals pass through a clamping circuit, amplifier circuit, voltage follower circuit, comparator circuit, and MCU. This conditioning circuit solution effectively prevents false triggering and enhances the circuit's anti-interference capabilities. However, existing technologies fail to account for signal strength differences and dynamically adjust comparator thresholds. Consequently, signal acquisition reliability is low under complex operating conditions, and sensor status detection is also lacking. Summary of the Invention

[0005] The purpose of the present invention is to provide a magnetoelectric speed sensor signal acquisition circuit and fault diagnosis method, which automatically switches the amplification factor based on the speed signal strength, raises the bipolar sine wave in the full frequency range to the unipolar range, and dynamically adjusts the comparator threshold voltage according to the signal peak value to increase the reliability of sensor fault detection.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: The present invention provides a magnetoelectric speed sensor signal acquisition circuit, comprising a first low-pass filter circuit, a limiter circuit, a lifting and adjustable amplification circuit, an adaptive peak detection circuit, a threshold adjustment circuit, an in-phase hysteresis comparison circuit, a fault detection circuit, a second low-pass filter circuit, and a single-chip microcomputer module; The low-pass filter circuit 1 is used to filter the output signal of the magnetoelectric speed sensor and output it to the limiting circuit; The amplitude limiting circuit is used to limit the peak value of the signal processed by the low-pass filter circuit; The lifting and adjustable amplification circuit is used to lift the peak bias of the signal after limiting, and amplify the signal by a certain multiple and output it to the adaptive peak detection circuit and the in-phase hysteresis comparison circuit; The adaptive peak detection circuit is used to detect and obtain the peak voltage of the input signal and output it to the threshold adjustment circuit; The threshold adjustment circuit is used to divide the peak voltage obtained by the adaptive peak detection and output it to the in-phase hysteresis comparison circuit; The in-phase hysteresis comparison circuit is used to compare the two input signals, and the output square wave signal is sent to the single chip microcomputer module through the second low-pass filter circuit to obtain the signal frequency value; The single chip microcomputer module is used to control the switching of the amplification factor of the lifting and adjustable amplification circuit based on the signal frequency value, and to control the fault detection circuit to perform fault detection on the magnetoelectric speed sensor.

[0007] Preferably, the output signal of the magnetoelectric speed sensor is connected to an input end of the low-pass filter circuit, an output end of the low-pass filter circuit is connected to the input end of the limiting circuit, the output end of the limiting circuit is connected to the input end of the lifting and adjustable amplifier circuit, the lifting and adjustable amplifier output end is connected to the input end of the adaptive peak detection circuit, the input end of the in-phase hysteresis comparison circuit and the single-chip microcomputer module, the adaptive peak detection output end is connected to the threshold adjustment input end, the threshold adjustment output end is connected to the input end of the in-phase hysteresis comparison circuit, the output end of the in-phase hysteresis comparison circuit is connected to the second input end of the low-pass filter circuit, the second output end of the low-pass filter circuit is connected to the single-chip microcomputer module, the output end of the fault detection circuit is connected to the output end of the low-pass filter circuit and the single-chip microcomputer module, and the input end of the fault detection circuit is connected to the single-chip microcomputer module.

[0008] Preferably, the amplitude limiting circuit is used to limit the peak value of the signal processed by the low-pass filter circuit to ±0.6V.

[0009] Preferably, the threshold adjustment circuit is used to divide the peak voltage obtained by the adaptive peak detection to obtain Vth, and Vth is 2 / 3 of the peak voltage.

[0010] Preferably, the low-pass filter circuit 1 includes a resistor R6 and a capacitor C1, one end of the resistor R6 is connected to the output end of the magnetoelectric speed sensor, and the other end is connected to one end of the capacitor C1, and the other end of the capacitor C1 is grounded.

[0011] Preferably, the fault detection circuit includes an NMOS tube Q1, a resistor R1 and a resistor R2, the source of the NMOS tube Q1 is connected to one end of the capacitor C1, the gate is connected to the single-chip computer module, the drain is connected to one end of the resistor R1 and the resistor R2, the other end of the resistor R1 is connected to the power supply VCC5, and the other end of the resistor R2 is connected to the single-chip computer module.

[0012] Preferably, the amplitude limiting circuit includes a diode D2, a pin 3 of the diode D2 is connected to the capacitor C1, the resistor R6 and one end of the source of the NMOS transistor Q1, and the pin 1 and the pin 2 are connected to the ground.

[0013] Preferably, the lifting and adjustable amplification circuit includes a resistor R4, a resistor R5, a resistor R7, a resistor R9, a resistor R10, an op amp U2A and an analog switch U1, one end of the resistor R7 is connected to pin 3 of the diode D2, the other end of the resistor R7 is connected to the resistor R4, the resistor R5 and the inverting input of the op amp U2A, the other end of the resistor R4 is connected to the Y1 pin of the analog switch U1, the other end of the resistor R5 is connected to the Y0 pin of the analog switch U1, one end of the resistor R9 and the resistor R10 is connected to the non-inverting input of the op amp U2A, the other end of the resistor R9 is connected to the reference power supply VREF, the other end of the resistor R10 is grounded, and the output of the op amp U2A is connected to the common terminal Z pin of the analog switch U1.

[0014] Preferably, the adaptive peak detection circuit includes an op amp U2B and an op amp U2C, a diode D1, a diode D3, a resistor R3, a resistor R16, a capacitor C5 and an NMOS tube Q2, the non-inverting input terminal of the op amp U2B is connected to the output terminal of the op amp U2A, the inverting input terminal of the op amp U2B is connected to the anode of the diode D1 and one end of the resistor R3, the output terminal of the op amp U2B is connected to the cathode of the diode D1 and the anode of the diode D3, the cathode of the diode D3 is connected to the capacitor C5, the resistor R6 and the non-inverting input terminal of the op amp U2C, the other end of the capacitor C5 is grounded, the other end of the resistor R16 is connected to the drain of the NMOS tube Q2, the source of the NMOS tube Q2 is grounded, the gate of the NMOS tube Q2 is connected to the single-chip computer module, and the inverting input terminal of the op amp U2C is connected to the other end of the resistor R3 and the output terminal of the op amp U2C.

[0015] Preferably, the threshold adjustment circuit includes a resistor R11 and a resistor R8, the resistor R8 is connected to the output end of the operational amplifier U2C, the other end of the resistor R8 is connected to the resistor R11, and the other end of the resistor R11 is grounded.

[0016] Preferably, the in-phase hysteresis comparison circuit includes a capacitor C2, a capacitor C3, a resistor R12, a resistor R14, a resistor R15 and a comparator U3A, the negative input end of the comparator U3A is connected to the capacitor C2, the resistor R8 and the resistor R11, the other end of the capacitor C2 is grounded, the output end of the comparator U3A is connected to the resistor R12 and the resistor R15, the other end of the resistor R12 is connected to the power supply VCC3P3, the other end of the resistor R15 is connected to the positive input end of the comparator U3A, one end of the capacitor C3 is connected to the positive input end of the comparator U3A and the resistor R14, the other end of the capacitor C3 is grounded, and the other end of the resistor R14 is connected to the in-phase input end of the op amp U2B.

[0017] Preferably, the second low-pass filter circuit includes a resistor R13 and a capacitor C4, the resistor R13 is connected to the resistor R12, the output end of the comparator U3A and the resistor R15, the other end of the resistor R13 is connected to the capacitor C4 and the single-chip computer module, and the other end of the capacitor C4 is grounded.

[0018] Preferably, the single chip microcomputer module controls the switching of the amplification factor of the lifting and adjustable amplification circuit based on the signal frequency value, including: When the signal frequency value is detected to be less than the set frequency threshold Pth, the analog switches S0, S1, and S2 of the control lift and adjustable amplifier circuit U1 are all low, turning on the Y0 channel and using the amplification factor A1, where A1=-R5 / R7; When the signal frequency value is detected to be greater than the set frequency threshold Pth, the analog switch U1 of the lifting and adjustable amplifier circuit is controlled to be low level, S2 is high level, the Y1 channel is turned on, and the amplification factor A0 is adopted, where A0=-R4 / R7, and A1>A0; The output signal Uo after lifting and amplification is: Uo=VP-A0* Ui ’ Or Uo=VP-A1*Ui ’ , And the A1* Ui ’ Must be less than or equal to VP; Among them, VP is the voltage after lifting, Ui ’ It is the voltage value after being processed by the limiting circuit.

[0019] Preferably, the single chip microcomputer module controls the fault detection circuit to perform magnetoelectric speed sensor fault detection, including: Before the transmission controller of the magnetoelectric speed sensor is powered on and works, perform fault detection on the magnetoelectric speed sensor. The process is as follows: During fault detection, the single chip microcomputer module controls the NMOS tube Q1 of the fault detection circuit to turn on and increase the pull-up resistor. Since the sensor itself has internal resistance, a static voltage division relationship is generated. The voltage after voltage division is V PI_DEC , If the collected voltage V PI_DEC If the value is greater than or equal to 0.95VCC5, it is determined to be a sensor signal line break fault or an internal open circuit fault of the sensor; If the collected voltage V PI_DEC Less than or equal to 0.05VCC5, it is determined to be a sensor signal line short circuit fault or a sensor internal short circuit fault; If the collected voltage V PI_DEC If the sensor is within ±10% of the theoretical amplitude, there is no abnormality in the sensor circuit and internal parts; If the collected voltage V PI_DEC If the value is outside the theoretical amplitude range and does not meet the requirements of being greater than or equal to 0.95VCC5 and less than or equal to 0.05VCC5, it is determined that the sensor characteristics are abnormal.

[0020] Preferably, the adaptive peak detection circuit detects and obtains the peak voltage of the input signal in the following manner: When the output signal of the boost and adjustable amplification circuit passes through the non-inverting input terminal voltage of the operational amplifier U2B and is higher than the inverting input terminal voltage, the diode D3 is turned on and the diode D1 is turned off, and the capacitor C5 starts to charge. After the capacitor C5 is fully charged, it maintains the peak voltage; if a new peak value appears, the capacitor C5 continues to charge to update and maintain the maximum peak voltage.

[0021] The present invention also provides a magnetoelectric speed sensor fault diagnosis method, which is implemented based on the above-mentioned magnetoelectric speed sensor signal acquisition circuit, and the method includes: Before the transmission controller of the magnetoelectric speed sensor is powered on and works, perform fault detection on the magnetoelectric speed sensor. The process is as follows: During fault detection, the NMOS tube Q1 of the fault detection circuit is turned on by the single chip module to increase the pull-up resistance. Since the sensor itself has internal resistance, a static voltage division relationship is generated. The voltage after voltage division is V PI_DEC , If the collected voltage V PI_DEC If the value is greater than or equal to 0.95VCC5, it is determined to be a sensor signal line break fault or an internal open circuit fault of the sensor; If the collected voltage V PI_DECLess than or equal to 0.05VCC5, it is determined to be a sensor signal line short circuit fault or a sensor internal short circuit fault; If the collected voltage V PI_DEC If the sensor is within ±10% of the theoretical amplitude, there is no abnormality in the sensor circuit and internal parts; If the collected voltage V PI_DEC If the value is outside the theoretical amplitude range and does not meet the requirements of being greater than or equal to 0.95VCC5 and less than or equal to 0.05VCC5, it is determined that the sensor characteristics are abnormal.

[0022] The beneficial effects brought about by the technical solution of the present invention are as follows: The present invention discloses a magnetoelectric speed sensor signal acquisition circuit and fault diagnosis method, which automatically switches the amplification factor according to the speed signal strength, with a large amplification factor for small signals and a small amplification factor for large signals, thereby improving signal acquisition reliability. The present invention converts the full frequency range bipolarity into a unipolar range through a lifting and amplifying circuit to ensure signal integrity; The present invention provides sensor input signal peak detection and dynamic adjustment of comparator threshold voltage, so that signals with different peak values can reliably identify threshold voltages, while enhancing anti-interference capabilities; The present invention provides fault diagnosis of sensor input status to avoid misjudgment or controller failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a signal acquisition circuit for a magnetoelectric speed sensor provided by an embodiment of the present invention; Figure 2 A schematic diagram of the principle of a magnetoelectric speed sensor signal acquisition circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0025] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, the accompanying drawings only show structures and / or processing steps closely related to the solutions according to the present invention, while other details that are not closely related to the present invention are omitted.

[0026] It should be emphasized that the term "include / comprises" when used herein refers to the existence of features, elements, steps or components, but does not exclude the existence or addition of one or more other features, elements, steps or components.

[0027] It should also be noted that, unless otherwise specified, the term "connection" herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0029] It should be emphasized here that the step marks mentioned below do not limit the order of the steps, but it should be understood that the steps can be executed in the order mentioned in the embodiment, or in a different order from the embodiment, or several steps can be executed simultaneously. Example 1

[0030] This embodiment 1 provides a magnetoelectric speed sensor signal acquisition circuit, such as Figure 1 As shown, it includes a low-pass filter circuit 1, a limiting circuit, a lifting and adjustable amplification circuit, an adaptive peak detection circuit, a threshold adjustment circuit, an in-phase hysteresis comparison circuit, a fault detection circuit, a low-pass filter circuit 2 and a single-chip microcomputer module.

[0031] The output signal of the magnetoelectric speed sensor is connected to an input end of a low-pass filter circuit, an output end of the low-pass filter circuit is connected to an input end of a limiting circuit, an output end of the limiting circuit is connected to an input end of a lifting and adjustable amplifier circuit, an output end of the lifting and adjustable amplifier is connected to an input end of an adaptive peak detection circuit, an input end of an in-phase hysteresis comparison circuit and a single-chip microcomputer module, an output end of an adaptive peak detection circuit is connected to an input end of a threshold adjustment, an output end of a threshold adjustment is connected to an input end of an in-phase hysteresis comparison circuit, an output end of an in-phase hysteresis comparison circuit is connected to an input end of a low-pass filter circuit, an output end of a low-pass filter circuit is connected to an output end of a low-pass filter circuit and a single-chip microcomputer module, an output end of a fault detection circuit is connected to an output end of a low-pass filter circuit and a single-chip microcomputer module, and an input end of a fault detection circuit is connected to a single-chip microcomputer module.

[0032] See also Figure 2 In this embodiment, the low-pass filter circuit 1 includes a resistor R6 and a capacitor C1. One end of the resistor R6 is connected to the output end of the magnetoelectric speed sensor, and the other end is connected to one end of the capacitor C1. The other end of the capacitor C1 is grounded.

[0033] In this embodiment, the fault detection circuit includes an NMOS transistor Q1, a resistor R1, and a resistor R2. The source of the NMOS transistor Q1 is connected to one end of the capacitor C1, the gate is connected to the microcontroller module, the drain is connected to one end of the resistor R1 and the resistor R2, the other end of the resistor R1 is connected to the power supply VCC5, and the other end of the resistor R2 is connected to the microcontroller module.

[0034] In this embodiment, the limiter circuit includes a diode D2. Pin 3 of diode D2 is connected to capacitor C1, resistor R6, and one end of the source of NMOS transistor Q1. Pins 1 and 2 of diode D2 are connected to ground. The limiter circuit is used to limit the peak value of the output signal of the magnetoelectric speed sensor (peak range 0.1V to 15V) to ±0.6V to ensure that it does not affect the downstream circuitry.

[0035] In this embodiment, the boost and adjustable amplifier circuit includes resistors R4, R5, R7, R9, and R10, an op amp U2A, and an analog switch U1. One end of resistor R7 is connected to pin 3 of diode D2, and the other end of resistor R7 is connected to resistors R4, R5, and the inverting input of U2A. The other end of resistor R4 is connected to pin Y1 of analog switch U1, and the other end of resistor R5 is connected to pin Y0 of analog switch U1. One end of resistors R9 and R10 is connected to the non-inverting input of op amp U2A, the other end of resistor R9 is connected to reference power supply VREF, and the other end of resistor R10 is grounded. The output of op amp U2A is connected to the common pin Z of analog switch U1. The boost and adjustable amplifier circuit is used to boost the bias of a signal with a peak value of ±0.6V after clipping from 0V to VP, where VP = Uref*R10 / (R9+R10), amplify the signal by a certain factor, and output it to the adaptive peak detection circuit and the in-phase hysteresis comparator circuit.

[0036] In this embodiment, the adaptive peak detection circuit includes op amps U2B and U2C, diodes D1 and D3, resistors R3 and R16, capacitor C5, and NMOS transistor Q2. The non-inverting input of op amp U2B is connected to the output of op amp U2A, the inverting input of op amp U2B is connected to the anode of diode D1 and one end of resistor R3, the output of op amp U2B is connected to the cathode of diode D1 and the anode of diode D3, the cathode of diode D3 is connected to capacitor C5, resistor R6, and the non-inverting input of op amp U2C, the other end of capacitor C5 is grounded, the other end of resistor R16 is connected to the drain of NMOS transistor Q2, the source of NMOS transistor Q2 is grounded, and the gate of NMOS transistor Q2 is connected to the microcontroller module. The inverting input of op amp U2C is connected to the other end of resistor R3 and the output of op amp U2C. The adaptive peak detection circuit is used to detect and obtain the peak voltage of the input signal.

[0037] In this embodiment, the threshold adjustment circuit includes resistors R11 and R8. Resistor R8 is connected to the output of op amp U2C. The other end of resistor R8 is connected to resistor R11. The other end of resistor R11 is grounded. The threshold adjustment circuit is used to divide the peak voltage VPP obtained by adaptive peak detection by resistors to obtain Vth. Vth is typically selected as 2 / 3 of VPP and is output to the in-phase hysteresis comparator circuit.

[0038] In this embodiment, the in-phase hysteresis comparator circuit includes capacitor C2, capacitor C3, resistor R12, resistor R14, resistor R15, and comparator U3A. The negative input of comparator U3A is connected to capacitor C2, resistor R8, and resistor R11. The other end of capacitor C2 is grounded. The output of comparator U3A is connected to resistors R12 and R15. The other end of resistor R12 is connected to power supply VCC3P3. The other end of resistor R15 is connected to the positive input of comparator U3A. One end of capacitor C3 is connected to the positive input of comparator U3A and resistor R14. The other end of capacitor C3 is grounded. The other end of resistor R14 is connected to the in-phase input of op amp U2B. The in-phase hysteresis comparator circuit compares its input signal (i.e., the output signal after the boost and adjustable amplification circuit) with a threshold value adjusted by the adaptive peak detection and threshold adjustment circuit. The output square wave signal is sent to the microcontroller module through low-pass filter circuit 2 to obtain the signal frequency.

[0039] In this embodiment, the second low-pass filter circuit includes a resistor R13 and a capacitor C4. The resistor R13 is connected to the resistor R12, the output end of the comparator U3A and the resistor R15. The other end of the resistor R13 is connected to the capacitor C4 and the microcontroller module. The other end of the capacitor C4 is grounded.

[0040] In this embodiment, the single chip microcomputer module is specifically used to: By controlling the on and off of the analog switch U1 of the lifting and adjustable amplifier circuit, the switching of the amplification factor of the lifting and adjustable amplifier circuit is achieved; Processing the square wave signal output by the in-phase hysteresis comparison circuit to obtain the signal frequency; as well as, The NMOS tube Q1 of the fault detection circuit is turned on to increase the pull-up resistance, thereby realizing the fault detection of the magnetoelectric speed sensor.

[0041] In this embodiment, the boost and adjustable amplifier circuit boosts the signal bias of the peak value of ±0.6V after limiting from 0V to VP, where VP = Uref*R10 / (R9+R10), where Uref is the reference power supply. VP is typically VCC5 / 2, or 2.5V.

[0042] In this embodiment, the boost and adjustable amplification circuit amplifies the signal by a certain multiple, specifically: The magnification is: A0=-R4 / R7 or A1=-R5 / R7 (A1>A0), In this embodiment, the magnification switching is achieved by controlling the on and off of the analog switch via the single chip microcomputer module. When the single-chip microcomputer module detects that the signal frequency value is less than the set frequency threshold Pth, the single-chip microcomputer module controls S0, S1, and S2 of the analog switch U1 to low levels, turns on the Y0 channel, and uses the amplification factor A1; when the single-chip microcomputer module detects that the signal frequency value is greater than the set frequency threshold Pth, the single-chip microcomputer module controls S0 and S1 of the analog switch U1 to low levels, S2 to high levels, turns on the Y1 channel, and uses the amplification factor A0.

[0043] The output signal after lifting and amplification is: Uo=VP-A0* Ui ’ Or Uo=VP-A1*Ui ’ , Among them, Ui ’ It is the output signal of the magnetoelectric speed sensor after being processed by the limiting circuit.

[0044] Furthermore, to ensure that the entire frequency range is raised above 0V, A1* Ui ’ Must be less than or equal to VP.

[0045] In this embodiment, the adaptive peak detection circuit operates as follows: When the output signal of the boost and adjustable amplifier circuit passes through the non-inverting input terminal 5 of op amp U2B and the voltage is higher than the inverting input terminal 6, diode D3 turns on, diode D1 turns off, and capacitor C5 begins charging. Due to the unidirectional conductivity of diode D3, capacitor C5 maintains its peak voltage after being fully charged. Diode D1, resistor R3, and op amp U2C form a negative feedback circuit to prevent op amp U2B from entering a negative saturation state. If a new peak value appears in the signal, capacitor C5 continues to charge, updating and maintaining the maximum peak voltage. At the same time, NMOS transistor Q2 is periodically turned on and off, periodically discharging capacitor C5 when on and periodically charging capacitor C5 when off. It should be noted that if the current peak-to-peak value is Vp, when the peak-to-peak value of the signal is greater than Vp at the next moment, the peak value collected will be updated in real time. However, if the peak-to-peak value of the signal is less than Vp at the next moment, if it is not discharged through resistor R16, the collected peak-to-peak value will remain unchanged. Therefore, it is necessary to periodically turn NMOS transistor Q2 on and off to achieve discharge.

[0046] In this embodiment, the fault detection circuit performs fault detection on the magnetoelectric speed sensor before the transmission controller is powered on and working, to determine whether it is normal. The fault detection process is as follows: During fault detection, the MCU module controls the NMOS tube Q1 to conduct and increase the pull-up resistor (usually 2KΩ, which can be adjusted according to the internal resistance of the sensor). Since the sensor itself has an internal resistance, usually around 400Ω (which does not change much at high or low temperatures), a static voltage division relationship is generated. The voltage after voltage division is V PI_DEC It should be noted that the voltage divider V PI_DECIt is obtained by dividing the voltage VCC5 by the resistor R1 and the internal resistance of the sensor after the single chip controls the NMOS tube Q1 to turn on; If the collected voltage V PI_DEC If it is approximately equal to VCC5 (greater than or equal to 0.95VCC5), it is determined to be a sensor signal line break fault or an internal open circuit fault in the sensor; If the collected voltage V PI_DEC If it is equal to 0V (less than or equal to 0.05VCC5), it is determined to be a sensor signal line short circuit fault or a sensor internal short circuit fault; If the collected voltage V PI_DEC If the sensor is within ±10% of the theoretical amplitude, there is no abnormality in the sensor circuit and internal parts; If the collected voltage V PI_DEC If the value is not within the theoretical amplitude range and is not approximately equal to VCC5 or 0V, it is determined that the sensor characteristics are abnormal.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A magnetoelectric speed sensor signal acquisition circuit, characterized in that: It includes a low-pass filter circuit 1, a limiter circuit, a lifting and adjustable amplifier circuit, an adaptive peak detection circuit, a threshold adjustment circuit, an in-phase hysteresis comparison circuit, a fault detection circuit, a low-pass filter circuit 2 and a single-chip microcomputer module; The low-pass filter circuit 1 is used to filter the output signal of the magnetoelectric speed sensor and output it to the limiting circuit; The amplitude limiting circuit is used to limit the peak value of the signal processed by the low-pass filter circuit; The lifting and adjustable amplification circuit is used to lift the peak bias of the signal after limiting, and amplify the signal by a certain multiple and output it to the adaptive peak detection circuit and the in-phase hysteresis comparison circuit; The adaptive peak detection circuit is used to detect and obtain the peak voltage of the input signal and output it to the threshold adjustment circuit; The threshold adjustment circuit is used to divide the peak voltage obtained by the adaptive peak detection and output it to the in-phase hysteresis comparison circuit; The in-phase hysteresis comparison circuit is used to compare the two input signals, and the output square wave signal is sent to the single chip microcomputer module through the second low-pass filter circuit to obtain the signal frequency value; The single chip microcomputer module is used to control the switching of the amplification factor of the lifting and adjustable amplification circuit based on the signal frequency value, and to control the fault detection circuit to perform fault detection on the magnetoelectric speed sensor.

2. The magnetoelectric speed sensor signal acquisition circuit according to claim 1, characterized in that: The output signal of the magnetoelectric speed sensor is connected to an input end of the low-pass filter circuit, an output end of the low-pass filter circuit is connected to the input end of the limiter circuit, the output end of the limiter circuit is connected to the input end of the lifting and adjustable amplifier circuit, the lifting and adjustable amplifier output end is connected to the input end of the adaptive peak detection circuit, the input end of the in-phase hysteresis comparison circuit and the single-chip microcomputer module, the adaptive peak detection output end is connected to the threshold adjustment input end, the threshold adjustment output end is connected to the input end of the in-phase hysteresis comparison circuit, the output end of the in-phase hysteresis comparison circuit is connected to the second input end of the low-pass filter circuit, the second output end of the low-pass filter circuit is connected to the single-chip microcomputer module, the output end of the fault detection circuit is connected to the output end of the low-pass filter circuit and the single-chip microcomputer module, and the input end of the fault detection circuit is connected to the single-chip microcomputer module.

3. The magnetoelectric speed sensor signal acquisition circuit according to claim 2, characterized in that: The amplitude limiting circuit is used to limit the peak value of the signal processed by the low-pass filter circuit to ±0.6V.

4. The magnetoelectric speed sensor signal acquisition circuit according to claim 2, characterized in that: The threshold adjustment circuit is used to divide the peak voltage obtained by the adaptive peak detection to obtain Vth, where Vth is 2 / 3 of the peak voltage.

5. The magnetoelectric speed sensor signal acquisition circuit according to claim 2, characterized in that: The low-pass filter circuit 1 includes a resistor R6 and a capacitor C1. One end of the resistor R6 is connected to the output end of the magnetoelectric speed sensor, and the other end is connected to one end of the capacitor C1. The other end of the capacitor C1 is grounded.

6. The magnetoelectric speed sensor signal acquisition circuit according to claim 5, characterized in that: The fault detection circuit includes an NMOS transistor Q1, a resistor R1 and a resistor R2. The source of the NMOS transistor Q1 is connected to one end of the capacitor C1, the gate is connected to the microcontroller module, the drain is connected to one end of the resistor R1 and the resistor R2, the other end of the resistor R1 is connected to the power supply VCC5, and the other end of the resistor R2 is connected to the microcontroller module.

7. The magnetoelectric speed sensor signal acquisition circuit according to claim 6, characterized in that: The amplitude limiting circuit includes a diode D2 , wherein a pin 3 of the diode D2 is connected to the capacitor C1 , the resistor R6 and one end of the source of the NMOS transistor Q1 , and the pin 1 and the pin 2 are connected to the ground.

8. The magnetoelectric speed sensor signal acquisition circuit according to claim 7, characterized in that: The lifting and adjustable amplification circuit includes resistor R4, resistor R5, resistor R7, resistor R9, resistor R10, op amp U2A and analog switch U1, one end of the resistor R7 is connected to pin 3 of the diode D2, the other end of the resistor R7 is connected to resistor R4, resistor R5 and the inverting input of the op amp U2A, the other end of the resistor R4 is connected to the Y1 pin of the analog switch U1, the other end of the resistor R5 is connected to the Y0 pin of the analog switch U1, one end of the resistor R9 and the resistor R10 is connected to the non-inverting input of the op amp U2A, the other end of the resistor R9 is connected to the reference power supply VREF, the other end of the resistor R10 is grounded, and the output of the op amp U2A is connected to the common terminal Z pin of the analog switch U1.

9. The magnetoelectric speed sensor signal acquisition circuit according to claim 8, characterized in that: The adaptive peak detection circuit includes an op amp U2B and an op amp U2C, a diode D1, a diode D3, a resistor R3, a resistor R16, a capacitor C5 and an NMOS transistor Q2. The non-inverting input terminal of the op amp U2B is connected to the output terminal of the op amp U2A, the inverting input terminal of the op amp U2B is connected to the anode of the diode D1 and one end of the resistor R3, the output terminal of the op amp U2B is connected to the cathode of the diode D1 and the anode of the diode D3, the cathode of the diode D3 is connected to the capacitor C5, the resistor R6 and the non-inverting input terminal of the op amp U2C, the other end of the capacitor C5 is grounded, the other end of the resistor R16 is connected to the drain of the NMOS transistor Q2, the source of the NMOS transistor Q2 is grounded, the gate of the NMOS transistor Q2 is connected to the single-chip computer module, and the inverting input terminal of the op amp U2C is connected to the other end of the resistor R3 and the output terminal of the op amp U2C.

10. The magnetoelectric speed sensor signal acquisition circuit according to claim 9, characterized in that: The threshold adjustment circuit includes a resistor R11 and a resistor R8. The resistor R8 is connected to the output end of the operational amplifier U2C, the other end of the resistor R8 is connected to the resistor R11, and the other end of the resistor R11 is grounded.

11. The magnetoelectric speed sensor signal acquisition circuit according to claim 10, characterized in that: The in-phase hysteresis comparator circuit includes a capacitor C2, a capacitor C3, a resistor R12, a resistor R14, a resistor R15 and a comparator U3A. The negative input end of the comparator U3A is connected to the capacitor C2, the resistor R8 and the resistor R11, the other end of the capacitor C2 is grounded, the output end of the comparator U3A is connected to the resistor R12 and the resistor R15, the other end of the resistor R12 is connected to the power supply VCC3P3, the other end of the resistor R15 is connected to the positive input end of the comparator U3A, one end of the capacitor C3 is connected to the positive input end of the comparator U3A and the resistor R14, the other end of the capacitor C3 is grounded, and the other end of the resistor R14 is connected to the in-phase input end of the operational amplifier U2B.

12. The magnetoelectric speed sensor signal acquisition circuit according to claim 11, characterized in that: The second low-pass filter circuit includes a resistor R13 and a capacitor C4. The resistor R13 is connected to the resistor R12, the output end of the comparator U3A and the resistor R15. The other end of the resistor R13 is connected to the capacitor C4 and the single-chip microcomputer module. The other end of the capacitor C4 is grounded.

13. The magnetoelectric speed sensor signal acquisition circuit according to claim 12, characterized in that: The single chip microcomputer module controls the switching of the amplification factor of the lifting and adjustable amplification circuit based on the signal frequency value, including: When the signal frequency value is detected to be less than the set frequency threshold Pth, the analog switches S0, S1, and S2 of the control lift and adjustable amplifier circuit U1 are all low, turning on the Y0 channel and using the amplification factor A1, where A1=-R5 / R7; When the signal frequency value is detected to be greater than the set frequency threshold Pth, the analog switch U1 of the lifting and adjustable amplifier circuit is controlled to be low level, S2 is high level, the Y1 channel is turned on, and the amplification factor A0 is adopted, where A0=-R4 / R7, and A1>A0; The output signal Uo after lifting and amplification is: Uo = VP - A0 * Ui ’ or Uo = VP - A1 * Ui ’ , And the A1* Ui ’ Must be less than or equal to VP; Among them, VP is the voltage after lifting, Ui ’ It is the voltage value after being processed by the limiting circuit.

14. The magnetoelectric speed sensor signal acquisition circuit according to claim 12, characterized in that: The single chip microcomputer module controls the fault detection circuit to perform magnetoelectric speed sensor fault detection, including: Before the transmission controller of the magnetoelectric speed sensor is powered on and works, perform fault detection on the magnetoelectric speed sensor. The process is as follows: During fault detection, the single chip microcomputer module controls the NMOS tube Q1 of the fault detection circuit to turn on and increase the pull-up resistor. Since the sensor itself has internal resistance, a static voltage division relationship is generated. The voltage after voltage division is V PI_DEC , If the collected voltage V PI_DEC If the value is greater than or equal to 0.95VCC5, it is determined to be a sensor signal line break fault or an internal open circuit fault of the sensor; If the collected voltage V PI_DEC Less than or equal to 0.05VCC5, it is determined to be a sensor signal line short circuit fault or a sensor internal short circuit fault; If the collected voltage V PI_DEC If the sensor is within ±10% of the theoretical amplitude, there is no abnormality in the sensor circuit and internal parts; If the collected voltage V PI_DEC If the value is outside the theoretical amplitude range and does not meet the requirements of being greater than or equal to 0.95VCC5 and less than or equal to 0.05VCC5, it is determined that the sensor characteristics are abnormal.

15. The magnetoelectric speed sensor signal acquisition circuit according to claim 12, characterized in that: The adaptive peak detection circuit detects and obtains the peak voltage of the input signal in the following manner: When the output signal of the boost and adjustable amplification circuit passes through the non-inverting input terminal voltage of the operational amplifier U2B and is higher than the inverting input terminal voltage, the diode D3 is turned on and the diode D1 is turned off, and the capacitor C5 starts to charge. After the capacitor C5 is fully charged, it maintains the peak voltage; if a new peak value appears, the capacitor C5 continues to charge to update and maintain the maximum peak voltage.

16. A method for diagnosing faults of a magnetoelectric speed sensor, characterized in that: The method is implemented based on the magnetoelectric speed sensor signal acquisition circuit according to any one of claims 6 to 12, comprising: Before the transmission controller of the magnetoelectric speed sensor is powered on and works, perform fault detection on the magnetoelectric speed sensor. The process is as follows: During fault detection, the NMOS tube Q1 of the fault detection circuit is turned on by the single chip module to increase the pull-up resistance. Since the sensor itself has internal resistance, a static voltage division relationship is generated. The voltage after voltage division is V PI_DEC , If the collected voltage V PI_DEC If the value is greater than or equal to 0.95VCC5, it is determined to be a sensor signal line break fault or an internal open circuit fault of the sensor; If the collected voltage V PI_DEC Less than or equal to 0.05VCC5, it is determined to be a sensor signal line short circuit fault or a sensor internal short circuit fault; If the collected voltage V PI_DEC If the sensor is within ±10% of the theoretical amplitude, there is no abnormality in the sensor circuit and internal parts; If the collected voltage V PI_DEC If the value is outside the theoretical amplitude range and does not meet the requirements of being greater than or equal to 0.95VCC5 and less than or equal to 0.05VCC5, it is determined that the sensor characteristics are abnormal.

Images