CN-121977746-A - Fault detection circuit of pressure sensor and pressure sensor

CN121977746ACN 121977746 ACN121977746 ACN 121977746ACN-121977746-A

Abstract

The invention provides a fault detection circuit of a pressure sensor and the pressure sensor, and relates to the technical field of pressure sensor detection. The fault detection circuit comprises a signal source, a first filtering module and a first judging module, wherein the signal source is used for outputting a high-frequency signal to two differential output ends in the working state of the pressure sensor, the input end of the first filtering module is connected with the two differential output ends and used for filtering and differentiating signals of the two differential output ends and outputting differential signals, and the input end of the first judging module is connected with the output end of the first filtering module and used for acquiring the peak voltage of the differential signals and outputting short-circuit fault signals of the two differential output ends when the peak voltage is smaller than a short-circuit detection threshold value. According to the invention, high-frequency signals can be injected into the two differential output ends in the normal working process of the pressure sensor, the first filtering module is utilized to extract the high-frequency components for peak monitoring, and whether the differential output ends have short-circuit faults or not can be judged on line in real time while the pressure detection function is continuously executed by the sensor.

Inventors

LI MINGHAO
REN CHEN
ZHANG JIAYU
YANG YONGJUN

Assignees

河北美泰电子科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260331

Claims (10)

1. A fault detection circuit for a pressure sensor, for use with a pressure sensor comprising a resistive full bridge circuit having two differential outputs, the fault detection circuit comprising: The signal source is used for outputting high-frequency signals to the two differential output ends in the working state of the pressure sensor; The input end of the first filtering module is connected with the two differential output ends, and is used for filtering signals of the two differential output ends to extract high-frequency components, carrying out differential processing on the extracted two paths of high-frequency components, and outputting differential signals reflecting the difference value of the high-frequency components between the two differential output ends; The input end of the first judging module is connected with the output end of the first filtering module, and is used for acquiring the peak voltage of the differential signals and outputting fault signals representing the short circuit of the two differential output ends when the peak voltage is smaller than a short circuit detection threshold value; The frequency of the high-frequency signal is higher than the pressure change frequency of the pressure sensor during operation, and the first filtering module is provided with a high-pass cutoff frequency, wherein the high-pass cutoff frequency is lower than the frequency of the high-frequency signal and higher than the pressure change frequency.
2. The fault detection circuit of a pressure sensor of claim 1, wherein the high frequency signal is a square wave signal and the low level of the square wave signal is zero.
3. The fault detection circuit of a pressure sensor of claim 1, wherein the signal source outputs a first high frequency signal to a first differential output and a second high frequency signal to a second differential output; the first high-frequency signal and the second high-frequency signal have the same amplitude and opposite phases.
4. The fault detection circuit of a pressure sensor of claim 3, wherein the first filtering module comprises a filtering unit, a differential unit and a rectifying unit connected in series in sequence; The filtering unit filters the signals of the two differential output ends respectively and outputs the filtered signals of the two differential output ends to the differential unit; The differential unit is used for differentiating the filtering signals of the two differential output ends and outputting differential signals to the rectifying unit; The rectification unit performs full-wave rectification on the differential signals and outputs the rectified differential signals to the first judgment module.
5. The fault detection circuit of a pressure sensor of claim 4, wherein the filtering unit is a bandpass filter; the band-pass filter has a lower cut-off frequency equal to the high-pass cut-off frequency and an upper cut-off frequency greater than the frequency of the high-frequency signal.
6. The fault detection circuit of a pressure sensor of claim 1, wherein the first determination module comprises a first comparator; The non-inverting input end of the first comparator receives the differential signal, and the inverting input end of the first comparator receives a short circuit detection threshold; And the output end of the first comparator outputs a low level when the peak voltage of the differential signal is smaller than the short circuit detection threshold value, and the low level is used as a fault signal for representing the short circuit of the two differential output ends.
7. The fault detection circuit of a pressure sensor of claim 1, wherein the resistive full bridge circuit further comprises a power terminal and a ground terminal; the second judging module is selectively connected with the first differential output end or the second differential output end; The second judging module outputs a fault signal of short circuit between the first differential output end and the grounding end or disconnection between the first differential output end and the power supply end when the voltage of the signal of the first differential output end is smaller than the single-end detection low threshold value; The second judging module outputs a fault signal of short circuit between the second differential output end and the grounding end or disconnection between the second differential output end and the power supply end when the voltage of the signal of the second differential output end is smaller than the single-end detection low threshold value; The single-ended detection low threshold value is larger than or equal to the voltage of the grounding terminal and smaller than the lower limit of the voltage variation range of the two differential output terminals caused by pressure variation in normal operation.
8. The fault detection circuit of a pressure sensor of claim 7, further comprising a third determination module; the third judging module is alternatively connected with the first differential output end or the second differential output end; the third judging module outputs a fault signal of short circuit between the first differential output end and the power supply end or disconnection between the first differential output end and the grounding end when the voltage of the signal of the first differential output end is larger than the single-ended detection threshold value; the third judging module outputs a fault signal of short circuit between the second differential output end and the power supply end or disconnection between the second differential output end and the grounding end when the voltage of the signal of the second differential output end is larger than the single-ended detection threshold value; The single-ended detection threshold value is smaller than or equal to the voltage of the power supply end and is larger than the upper limit of the voltage change range of the two differential output ends caused by pressure change during normal operation.
9. The fault detection circuit of a pressure sensor of claim 7, wherein a first switch and a second switch are further provided between the second determination module and the two differential output terminals; one end of the first switch is connected with the first differential output end, and the other end of the first switch is connected with the second judging module; One end of the second switch is connected with a second differential output end, and the other end of the second switch is connected with a second judging module; The first switch and the second switch are alternatively closed.
10. A pressure sensor, characterized by comprising a fault detection circuit of a pressure sensor according to any of claims 1 to 9.

Description

Fault detection circuit of pressure sensor and pressure sensor Technical Field The present invention relates to the field of pressure sensor detection technologies, and in particular, to a fault detection circuit of a pressure sensor and a pressure sensor. Background The pressure sensor may convert the physical pressure into an electrical signal. The piezoresistive pressure sensor realizes pressure detection based on the piezoresistive effect and the Wheatstone resistance bridge, and the core detection structure is a Wheatstone resistance full bridge circuit. For the piezoresistive pressure sensor which is applied to the field of automobile electronics and has higher functional safety level requirements, the detection and monitoring of each key link of the whole sensor can be realized when the circuit design of the high-level functional safety requirement circuit is carried out. The voltage difference between the two differential outputs in a wheatstone resistive bridge is used to represent the pressure magnitude. In order to meet the requirements of high functional safety level, various faults including short circuit of the differential output end must be detected in real time. One straightforward approach to fault detection is to monitor the resistance between the two outputs. However, in the sensor operating state, the resistance value is superimposed on the amount of resistance change caused by the pressure signal, and it is difficult to directly separate and accurately measure. If an online resistance measurement scheme is adopted, a complex excitation source and a measurement circuit are required to extract weak resistance change from a dynamic pressure signal, which not only increases circuit cost and design complexity, but also is extremely easy to interfere with the pressure signal in measurement accuracy. Therefore, in the prior art, resistance measurement can only be performed through external special equipment under the condition that the sensor is offline and no pressure is input, and real-time and online fault diagnosis in the working state cannot be realized, which is contrary to the increasing high-functional safety requirement in the field of automobile electronics. Disclosure of Invention The embodiment of the invention provides a fault detection circuit of a pressure sensor and the pressure sensor, which are used for solving the problem that the existing mode cannot detect faults of two differential output ends in real time under the working state of the pressure sensor. In a first aspect, the embodiment of the invention provides a fault detection circuit of a pressure sensor, which is applied to the pressure sensor comprising a resistor full-bridge circuit, wherein the resistor full-bridge circuit is provided with two differential output ends, the fault detection circuit comprises a signal source, a first filtering module and a first judging module, wherein the signal source is used for outputting a high-frequency signal to the two differential output ends in the working state of the pressure sensor, the first filtering module is connected with the two differential output ends, is used for filtering signals of the two differential output ends to extract high-frequency components therein and carrying out differential processing on the extracted two high-frequency components to output a differential signal reflecting the difference value of the high-frequency components between the two differential output ends, the input end of the first judging module is connected with the output end of the first filtering module and used for acquiring the peak voltage of the differential signal and outputting a fault signal representing the short circuit of the two differential output ends when the peak voltage is smaller than a short circuit detection threshold value, and the first filtering module is provided with a high-pass frequency, and the high-pass frequency is lower than the high-pass frequency and higher than the high-pass frequency of the high-frequency signal when the pressure sensor works. In one possible implementation, the high frequency signal is a square wave signal and the low level of the square wave signal is zero. In one possible implementation manner, the signal source outputs a first high-frequency signal to the first differential output end and outputs a second high-frequency signal to the second differential output end, wherein the first high-frequency signal and the second high-frequency signal are identical in amplitude and opposite in phase. In a possible implementation manner, the first filtering module comprises a filtering unit, a differential unit and a rectifying unit which are sequentially connected in series, wherein the filtering unit filters signals of two differential output ends respectively and outputs the filtered signals of the two differential output ends to the differential unit, the differential unit carries out differential operation on the filtered signals o