Sensor measurement circuit, sensor, and vehicle

Abstract

The application provides a sensor measurement circuit, a sensor and a vehicle, and belongs to the technical field of sensors. The sensor measurement circuit comprises an operational amplifier, a sensitive circuit, a feedback circuit, a reference circuit and a ground terminal. The feedback circuit is electrically connected with an output end and a reverse input end of the operational amplifier. The sensitive circuit is electrically connected with the reverse input end and the ground terminal. The resistance value of the sensitive circuit changes with the change of a measured parameter. The reference circuit is electrically connected with a forward input end of the operational amplifier, and is used for inputting a reference voltage signal to the operational amplifier. The operational amplifier is used for outputting a measurement voltage signal corresponding to the change of the measured parameter according to the reference voltage signal and an amplification multiple. The measurement of the measured parameter can be realized, and the circuit structure of the sensor measurement circuit is simplified.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a sensor measurement circuit, a sensor and a vehicle. BACKGROUND

[0002] The methods commonly used for resistance value measurement are constant current method and voltage division method. The constant current method is to calculate the resistance value by collecting the voltage across the resistance to be measured and the constant current output by the constant current source according to Ohm's law. The voltage division method is to realize resistance value measurement by dividing a constant voltage by the resistance to be measured and a known resistance.

[0003] The resistance type sensor converts the change of the measured parameter into the change of the sensor resistance, and realizes parameter measurement by detecting the sensor resistance. The resistance value of the resistance type sensor may be in the order of magnitude of ohm (Ω) to several kilo-ohms (kΩ) or even mega-ohms (MΩ). In the prior art, whether it is the constant current method or the voltage division method, the resistance value in different orders of magnitude is usually measured by grading.

[0004] However, different voltage dividing resistors or gain resistors need to be designed for each gear during grading measurement, and switches and switch control circuits for isolating different gears are also needed. In addition, a complex gear switching logic circuit is required. Therefore, the existing sensor measurement circuit has the problem of complex circuit. SUMMARY

[0005] The embodiments of the present application provide a sensor measurement circuit, a sensor and a vehicle to solve the problem of complex circuit of the existing sensor measurement circuit.

[0006] In a first aspect, the embodiments of the present application provide a sensor measurement circuit, comprising: an operational amplifier, a sensitive circuit, a feedback circuit, a reference circuit and a ground terminal;

[0007] The feedback circuit and the output terminal and the inverting input terminal of the operational amplifier are electrically connected respectively;

[0008] The sensitive circuit and the inverting input terminal and the ground terminal are electrically connected respectively; wherein the resistance value of the sensitive circuit changes with the change of the measured parameter;

[0009] The reference circuit is electrically connected with the non-inverting input terminal of the operational amplifier, and is used to input a reference voltage signal to the operational amplifier;

[0010] The operational amplifier is used to output a measurement voltage signal corresponding to the measured parameter according to the reference voltage signal and the amplification factor.

[0011] Optionally, the sensitive circuit comprises a sensitive resistor.

[0012] The sensitive resistor is electrically connected with the ground end and the reverse input end respectively.

[0013] Optionally, the sensitive circuit further comprises a first resistor.

[0014] The first resistor is arranged between the sensitive resistor and the reverse input end and is electrically connected with the sensitive resistor and the reverse input end respectively.

[0015] Optionally, the feedback circuit comprises a second resistor and a first filter circuit.

[0016] The second resistor is electrically connected with the output end and the reverse input end respectively.

[0017] The first filter circuit is electrically connected with the output end and the reverse input end respectively and is connected in parallel with the second resistor.

[0018] Optionally, the reference circuit comprises a first power supply end and a voltage dividing circuit.

[0019] The voltage dividing circuit is electrically connected with the first power supply end and the ground end respectively, and is configured to divide a power voltage signal corresponding to the first power supply end to obtain the reference voltage signal.

[0020] The voltage dividing circuit is further electrically connected with the forward input end, and is configured to input the reference voltage signal into the operational amplifier through the forward input end.

[0021] Optionally, the voltage dividing circuit comprises a third resistor and a fourth resistor.

[0022] One end of the third resistor is electrically connected with the first power supply end, and the other end of the third resistor is electrically connected with the fourth resistor and the forward input end respectively.

[0023] The end of the fourth resistor connected with the third resistor is further electrically connected with the forward input end, and the other end of the fourth resistor is electrically connected with the ground end.

[0024] Optionally, the sensor measurement circuit further comprises a power supply circuit, and the operational amplifier further comprises a first power supply pin and a second power supply pin.

[0025] The power supply circuit is electrically connected with the first power supply pin.

[0026] The second power supply pin is electrically connected with the ground end.

[0027] Optionally, the power supply circuit comprises a second power supply end and a second filter circuit.

[0028] The second filter circuit is electrically connected with the second power supply end, the first power supply pin and the ground end respectively.

[0029] In a second aspect, the embodiments of the present application provide a sensor, comprising the sensor measurement circuit according to the first aspect.

[0030] In a third aspect, the embodiments of the present application provide a vehicle, comprising the sensor according to the second aspect.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] In the embodiments of the present application, the feedback circuit is electrically connected with the output end and the inverting input end of the operational amplifier, the sensing circuit is electrically connected with the inverting input end and the ground end, the reference circuit is electrically connected with the non-inverting input end of the operational amplifier, and a reference voltage signal is input to the operational amplifier. Therefore, the sensor measurement circuit constitutes a non-inverting amplifier circuit, and the resistance value of the sensing circuit is taken as a part of the non-inverting amplifier circuit, so that the resistance value of the sensing circuit is associated with the amplification factor of the non-inverting amplifier circuit. Compared with the way of grading measurement of resistors of different orders of magnitude in the prior art constant current method or the voltage division method, the complex circuit structure such as voltage division resistor, switch, switch control circuit and switching gear logic circuit can be avoided during grading measurement. Since the resistance value of the sensing circuit changes with the change of the measured parameter, the operational amplifier is used to output a measurement voltage signal corresponding to the measured parameter according to the reference voltage signal and the amplification factor. Therefore, the measurement of the measured parameter can be realized through the sensor measurement circuit, and the sensor measurement circuit has the advantage of simple circuit structure.

[0033] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiment description.

[0035] Figure 1 A structure schematic diagram of a sensor measurement circuit provided by the embodiments of the present application;

[0036] Figure 2 A structure schematic diagram of a sensor measurement circuit provided by the embodiments of the present application;

[0037] Figure 3 A relationship trend diagram of the resistance value of the sensing resistor and the measurement voltage signal provided by the embodiments of the present application;

[0038] Figure 4 Circuit schematic diagram of a Wheatstone bridge measurement sensor in the prior art;

[0039] Figure 5 Circuit schematic diagram of a Wheatstone bridge measurement sensor in the prior art;

[0040] Figure 6 Circuit schematic diagram of a constant current measurement sensor in the prior art.

[0041] Reference signs:

[0042] 10-sensor measurement circuit; 101-operational amplifier; 1011-output terminal; 1012-inverting input terminal; 1013-non-inverting input terminal; 1014-first power supply pin; 1015-second power supply pin; 102-sensitive circuit; 1021-sensitive resistor; 1022-first resistor; 1023-first capacitor; 103-feedback circuit; 1031-second resistor; 1032-second capacitor; 104-reference circuit; 1041-first power supply terminal; 1042-third resistor; 1043-fourth resistor; 105-ground terminal; 106-power supply circuit; 1061-second power supply terminal; 1062-third capacitor; 1063-fourth capacitor. DETAILED DESCRIPTION

[0043] Exemplary embodiments of the present application will be described herein below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0044] In the related art, a resistance type sensor measurement circuit can be used for detection of various mechanical quantities and thermal quantities, such as force, pressure, displacement, strain, speed, acceleration, temperature, and humidity. The resistance type sensor converts the change of the measured parameter into the change of the resistance parameter of the sensitive element in a certain way, and then converts it into the output of the voltage or current signal, thereby realizing the measurement of non-electric quantities. Since there are many materials and types of resistance, and many physical reasons for causing resistance change, the resistance type sensor has been widely used in many industries.

[0045] Figure 1 is one of the structural schematic diagrams of a sensor measurement circuit provided by the embodiments of the present application, and the sensor measurement circuit 10 includes an operational amplifier 101, a sensitive circuit 102, a feedback circuit 103, a reference circuit 104, and a ground terminal 105.

[0046] The feedback circuit 103 is electrically connected with the output end 1011 and the reverse input end 1012 of the operational amplifier 101 respectively;

[0047] The sensitive circuit 102 is electrically connected with the reverse input end 1012 and the ground end 105 respectively; wherein the resistance value of the sensitive circuit 102 changes with the change of the measured parameter;

[0048] The reference circuit 104 is electrically connected with the forward input end 1013 of the operational amplifier 101, for inputting the reference voltage signal to the operational amplifier;

[0049] The operational amplifier 101 is used for outputting the measurement voltage signal corresponding to the measured parameter according to the reference voltage signal and the amplification multiple.

[0050] In the embodiment of the application, the feedback circuit 103 is electrically connected with the output end 1011 and the reverse input end 1012 of the operational amplifier 101 respectively, and the measurement voltage signal outputted by the output end 1011 is fed back to the reverse input end 1012 of the operational amplifier 101 as the feedback, to form a negative feedback network, and the input voltage signal of the reverse input end 1012 is equivalent to the reference voltage signal inputted from the forward input end 1013. The closed loop gain of the sensor measurement circuit 10 only depends on the resistance values of the sensitive circuit 102 and the feedback circuit 103 respectively, and in the case that the resistance value of the sensitive circuit 102 changes with the change of the measured parameter, the closed loop gain of the sensor measurement circuit 10 changes accordingly, so that the operational amplifier 101 amplifies or attenuates the reference voltage signal according to the closed loop gain, and outputs the corresponding measurement voltage signal, and then the subsequent circuit such as the analog-digital conversion circuit calculates the change of the measured parameter according to the change of the measurement voltage signal. Wherein, the subsequent circuit can refer to the implementation mode in the prior art, and the embodiment of the application does not limit this.

[0051] In the embodiment of the present application, the operational amplifier 101 can be an operational amplifier, the feedback circuit 103 is electrically connected to the output terminal 1011 and the reverse input terminal 1012 of the operational amplifier, the sensitive circuit 102 is electrically connected to the reverse input terminal 1012 and the ground terminal 105, the reference circuit 104 is electrically connected to the forward input terminal 1013 of the operational amplifier, and the reference voltage signal is input to the operational amplifier. Since the reverse input terminal 1012 is grounded and the reference voltage signal is input to the operational amplifier from the forward input terminal 1013, the measurement voltage signal output from the output terminal 1011 has the same phase as the reference voltage signal, the sensor measurement circuit 10 constitutes a same-phase amplification circuit, and the resistance of the sensitive circuit 102 is taken as a part of the same-phase amplification circuit. The closed-loop gain of the sensor measurement circuit 10 is the sum of the resistances of the sensitive circuit 102 and the feedback circuit 103 divided by the resistance of the sensitive circuit 102. Therefore, when the resistance of the sensitive circuit 102 is large, the amplification multiple of the sensor measurement circuit 10 is small, and when the resistance of the sensitive circuit 102 is small, the amplification multiple of the sensor measurement circuit 10 is large. The resistance of the sensitive circuit 102 can be calculated according to the measurement voltage signal. It should be noted that the same-phase amplification circuit has the characteristics of high input impedance and low output impedance, is suitable for the application scene of high input impedance of the resistance type sensor, and can improve the practicability of the sensor measurement circuit 10.

[0052] In the embodiment of the present application, the sensitive circuit 102 can include a sensitive element, and the type of the sensitive element can be determined according to the physical property of the measured parameter. The sensitive element is a circuit element that can change its resistance according to the change of the measured parameter. For example, for a temperature sensor, the sensitive element can be a thermistor, and for a light-sensitive sensor, the sensitive element can be a light-sensitive resistor. Here, only examples are given, and the embodiment of the present application is not limited in this regard.

[0053] In the embodiment of the present application, the feedback circuit 103 is electrically connected to the output terminal 1011 and the reverse input terminal 1012 of the operational amplifier 101, the sensitive circuit 102 is electrically connected to the reverse input terminal 1012 and the ground terminal 105, the reference circuit 104 is electrically connected to the forward input terminal 1013 of the operational amplifier 101, and the reference voltage signal is input to the operational amplifier 101, so that the sensor measurement circuit 10 constitutes a non-inverting amplifier circuit, and the resistance of the sensitive circuit 102 is taken as a part of the non-inverting amplifier circuit, so that the resistance of the sensitive circuit 102 is associated with the amplification factor of the non-inverting amplifier circuit. Compared with the way of grading measurement of resistors of different orders of magnitude in the prior art constant current method or voltage division method, the complex circuit structure such as voltage division resistor, switch, switch control circuit and switching gear logic circuit can be avoided during grading measurement. Since the sensitive circuit 102 can generate a resistance variation according to the variation of the measured parameter, and the operational amplifier 101 is used to output a measurement voltage signal corresponding to the variation of the measured parameter according to the reference voltage signal and the resistance variation, the measurement of the measured parameter can be realized through the sensor measurement circuit 10, and the sensor measurement circuit 10 has the advantages of simple circuit structure.

[0054] Optionally, the sensitive circuit 102 comprises a sensitive resistor 1021.

[0055] The sensitive resistor 1021 is electrically connected to the ground terminal 105 and the reverse input terminal 1012, respectively.

[0056] In the embodiment of the present application, the sensitive resistor 1021 can be used as a sensitive element of the sensitive circuit 102 to generate a resistance variation according to the variation of the measured parameter. The sensitive resistor 1021 is, for example, a thermistor, a photoresistor or the like. The thermistor is usually made of semiconductor material, and most of them are negative temperature coefficient, that is, the resistance of the thermistor decreases with the increase of temperature, and can be used for temperature measurement of a temperature sensor. The photoresistor is a special resistor made of sulfurized or selenized material, and its working principle is based on internal photoelectric effect. The stronger the light is, the lower the resistance is, and it can be used for light intensity measurement of a light-sensitive sensor.

[0057] In a specific embodiment, the sensitive resistor 1021 is a thermistor, and the sensor measurement circuit 10 is used for temperature measurement. For example, for a measured temperature in the range of -40℃ to 100℃, the resistance variation range of the thermistor is 332kΩ to 0.65kΩ.

[0058] In the embodiment of the present application, the sensitive resistor 1021 can sense the variation of the measured parameter, so as to generate a corresponding resistance variation according to the variation of the measured parameter, the circuit structure is simple, the required circuit elements are less, and the hardware cost of the sensor measurement circuit 10 can be reduced.

[0059] Optionally, the sensitive circuit 102 further comprises a first resistor 1022.

[0060] The first resistor 1022 is arranged between the sensitive resistor 1021 and the reverse input end 1012 and is electrically connected to the sensitive resistor 1021 and the reverse input end 1012 respectively.

[0061] In the embodiment of the present application, the resistance value of the feedback circuit 103 is generally set to the same order of magnitude as the maximum value of the resistance value of the thermistor. For example, the resistance value of the sensitive resistor 1021 varies in the range of 332 kΩ to 0.65 kΩ, and the resistance value of the feedback circuit 103 can be 200 kΩ. The closed-loop gain of the sensor measurement circuit 10 can be the sum of the resistance values of the sensitive resistor 1021, the first resistor 1022 and the feedback circuit 103 divided by the sum of the resistance values of the sensitive resistor 1021 and the first resistor 1022. In actual application, if the sensitive resistor 1021 is directly connected to the reverse input end 1012, the minimum value of the resistance value of the sensitive resistor 1021 can be ignored in terms of the order of magnitude of the resistance value of the feedback circuit 103. Therefore, in the case that the resistance value of the sensitive resistor 1021 is the minimum value, the closed-loop gain of the sensor measurement circuit 10 can reach hundreds of times, which can cause the reference voltage signal to be excessively amplified and can cause the circuit to work abnormally. Therefore, by arranging the first resistor 1022, the amplification multiple of the reference voltage signal can be limited, and the abnormal working of the circuit can be avoided.

[0062] In the embodiment of the present application, the resistance value of the first resistor 1022 can be determined according to the amplification multiple of the measured parameter. For example, the resistance value of the sensitive resistor 1021 varies in the range of 332 kΩ to 0.65 kΩ, the resistance value of the feedback circuit 103 is 200 kΩ, and the resistance value of the first resistor 1022 can be 22 kΩ. When the sensor resistance value is 332 kΩ, the amplification multiple of the sensor measurement circuit 10 is 1.56 times, and when the sensor resistance value is 0.6752 kΩ, the amplification multiple is 9.82 times. Therefore, the user can set the amplification multiple through the first resistor 1022 to meet the parameter measurement requirement.

[0063] In the embodiment of the present application, since the sensitive resistor 1021 is electrically connected to the ground end 105 and the first resistor 1022 respectively, and the first resistor 1022 is electrically connected to the reverse input end 1012, the change of the measured parameter can be sensed by the sensitive resistor 1021 to generate resistance change, and the amplification multiple of the circuit can be limited by the first resistor 1022, so that the amplification multiple of the reference voltage signal is not excessively large after the sensitive resistor 1021 is directly connected to the reverse input end 1012, the circuit components can be prevented from being damaged, and the service life of the circuit can be improved.

[0064] Optionally, the sensitive circuit 103 further comprises a first capacitor 1023.

[0065] The first capacitor 1023 is electrically connected with the ground end 105 and the first resistor 1022 respectively, and is connected in parallel with the sensitive resistor 1021.

[0066] In the embodiment of the present application, in order to avoid the noise from the reverse input end 1012 into the operational amplifier 101, which affects the accuracy of the operational amplifier 101, a first capacitor 1023 can be connected in parallel at both ends of the sensitive resistor 1021. The first capacitor 1023 can filter high-frequency signals and provide electrostatic protection. The capacitance value of the first capacitor 1023 can be determined according to the circuit design and actual application requirements, for example, 100 picofarads (pF). This is only an example and the embodiment of the present application is not limited thereto.

[0067] In the embodiment of the present application, by electrically connecting the first capacitor 1023 with the ground end 105 and the first resistor 1022 respectively, and connecting in parallel with the sensitive resistor 1021, the electrostatic protection and noise filtering of the reverse input end 1012 can be achieved, which avoids the influence of noise on the accuracy of the operational amplifier 101, and improves the practicality of the sensor measurement circuit 10.

[0068] Optionally, the feedback circuit 103 comprises a second resistor 1031 and a first filter circuit.

[0069] The second resistor 1031 is electrically connected with the output end 1011 and the reverse input end 1012 respectively.

[0070] The first filter circuit is electrically connected with the output end 1011 and the reverse input end 1012 respectively, and is connected in parallel with the second resistor 1031.

[0071] In the embodiment of the present application, since the second resistor 1031 is electrically connected with the output end 1011 and the reverse input end 1012 respectively, the second resistor 1031 can be used as a feedback resistor of the non-inverting amplifier circuit, and the measurement voltage signal output by the output end 1011 of the operational amplifier 101 is fed back to the reverse input end 1012 to form a negative feedback network. Therefore, the second circuit can also be referred to as a negative feedback resistor.

[0072] In the embodiment of the present application, the operational amplifier 101 can be an operational amplifier. When the operational amplifier is working normally, its output end will necessarily output noise with a certain effective value. The size of the noise depends on the selection of internal devices of the operational amplifier, the design of the circuit, and the environment in which it is located. In order to avoid the output noise of the operational amplifier from entering the operational amplifier through the feedback circuit 103 from the reverse input end 1012, which affects the accuracy of the operational amplifier, a filter circuit can be provided in the feedback circuit 103 to filter the output noise of the operational amplifier, which also plays a role in electrostatic protection.

[0073] In some specific embodiments, the first filter circuit can simply employ a second capacitor 1032 connected in parallel with the second resistor 1031 and electrically connected to the output terminal 1011 and the inverting input terminal 1012, respectively. The capacitance of the second capacitor 1032 can be determined according to the circuit design and actual application requirements, for example, 100 pico Farad (pF). This is only an example, and the embodiments of the present application do not make any limitation in this regard.

[0074] In the embodiments of the present application, the second resistor 1031 and the first filter circuit are respectively electrically connected to the output terminal 1011 and the inverting input terminal 1012, and the first filter circuit is also connected in parallel with the second resistor 1031. In this way, the measurement voltage signal output by the output terminal 1011 of the operational amplifier 101 can be conveniently fed back to the inverting input terminal 1012 through the second resistor 1031 to form a negative feedback network. The inverting input terminal 1012 is subjected to noise filtering and electrostatic protection by the first filter circuit, thereby avoiding the influence of noise on the accuracy of the operational amplifier 101, and the practicability of the sensor measurement circuit 10 can be improved.

[0075] Optionally, the reference circuit 104 comprises a first power supply 1041 and a voltage dividing circuit.

[0076] The voltage dividing circuit is electrically connected to the first power supply 1041 and the ground terminal 105, respectively, for dividing the power voltage signal corresponding to the first power supply 1041 to obtain the reference voltage signal.

[0077] The voltage dividing circuit is also electrically connected to the non-inverting input terminal 1013 for inputting the reference voltage signal to the operational amplifier 101 through the non-inverting input terminal 1013.

[0078] In the embodiments of the present application, the first power supply 1041 is used to input a power voltage signal to the voltage dividing circuit. The voltage dividing circuit can comprise a resistor element, which can divide the power voltage signal to obtain a reference voltage signal, and input the reference voltage signal to the operational amplifier 101 through the non-inverting input terminal 1013. The number, connection mode and resistance value of the resistor element can be set according to actual requirements. Specifically, the voltage value of the power voltage signal to be used and the voltage value of the reference voltage signal required are determined, and the embodiments of the present application do not make any limitation in this regard.

[0079] In the embodiments of the present application, the voltage dividing circuit is electrically connected to the first power supply 1041 and the ground terminal 105, respectively, and the voltage dividing circuit is also electrically connected to the non-inverting input terminal 1013. In this way, the power voltage signal can be simply and conveniently divided to provide a reference voltage signal for the operational amplifier 101, and the circuit structure is simple, and the practicability of the sensor measurement circuit 10 can be improved.

[0080] Optionally, the voltage dividing circuit comprises a third resistor 1042 and a fourth resistor 1043;

[0081] One end of the third resistor 1042 is electrically connected with the first power supply 1041, and the other end of the third resistor 1042 is respectively electrically connected with the fourth resistor 1043 and the positive input end 1013;

[0082] The end of the fourth resistor 1043 connected with the third resistor 1042 is also electrically connected with the positive input end 1013, and the other end of the fourth resistor 1043 is electrically connected with the ground end 105.

[0083] In the embodiment of the present application, the voltage dividing circuit can be simply composed of two voltage dividing resistors, i.e. the third resistor 1042 and the fourth resistor 1043. The third resistor 1042 and the fourth resistor 1043 are connected in series, the other end of the third resistor 1042 connected with the fourth resistor 1043 is connected with the first power supply 1041, the other end of the fourth resistor 1043 connected with the third resistor 1042 is connected with the ground end, and a lead wire is drawn out between the third resistor 1042 and the fourth resistor 1043 and is electrically connected with the positive input end 1013 of the operational amplifier 101, so that the reference voltage signal is the voltage signal between the two ends of the fourth resistor 1043 which is the voltage to ground. The voltage dividing ratio of the power supply voltage signal can be determined according to the ratio of the third resistor 1042 and the fourth resistor 1043, and then the voltage value of the reference voltage signal can be determined according to the voltage value of the power supply voltage signal and the voltage dividing ratio.

[0084] In the embodiment of the present application, one end of the third resistor 1042 is electrically connected with the first power supply 1041, the other end of the third resistor 1042 is respectively electrically connected with the fourth resistor 1043 and the positive input end 1013, the end of the fourth resistor 1043 connected with the third resistor 1042 is also electrically connected with the positive input end 1013, and the other end of the fourth resistor 1043 is electrically connected with the ground end 105. In this way, the power supply voltage signal corresponding to the first power supply end can be simply and conveniently divided by the third resistor 1042 and the fourth resistor 1043 to obtain the reference voltage signal, and the reference voltage signal is input into the operational amplifier 101 through the positive input end 1013. The voltage dividing logic is simple, the circuit elements used are less, and the circuit structure can be simplified.

[0085] Optionally, the sensor measurement circuit 10 further comprises a power supply circuit 106; the operational amplifier 101 further comprises a first power supply pin 1014 and a second power supply pin 1015;

[0086] The power supply circuit 106 is electrically connected with the first power supply pin 1014;

[0087] The second power pin 1015 is electrically connected with the ground terminal 105.

[0088] In the embodiment of the present application, the operational amplifier 101 can be an operational amplifier, which can include a first power pin 1014 and a second power pin 1015, and can be powered by a single power supply or a double power supply. The sensor measurement circuit 10 of the embodiment of the present application can be powered by a single power supply, that is, the power supply circuit 106 is electrically connected with the first power pin 1014, and the second power pin 1015 is electrically connected with the ground terminal 105, so that the circuit structure can be simplified. The power supply of the power supply circuit 106 can be a linear DC voltage stabilizing power supply, which can improve the linearity of the signal from the first power pin 1014 of the operational amplifier, so that the operational amplifier can perform linear amplification and improve the accuracy of the measured voltage signal.

[0089] In the embodiment of the present application, the power supply circuit 106 is electrically connected with the first power pin 1014 of the operational amplifier 101, and the second power pin 1015 is electrically connected with the ground terminal 105, so that the operational amplifier 101 can be powered by a single power supply, and the circuit structure can be simplified.

[0090] Optionally, the power supply circuit 106 includes a second power terminal 1061 and a second filter circuit.

[0091] The second filter circuit is electrically connected with the second power terminal 1061, the first power pin 1014 and the ground terminal, respectively.

[0092] In the embodiment of the present application, in order to avoid the influence of power supply noise on the measurement accuracy of the operational amplifier, a filter circuit can be arranged in the power supply circuit 106 to filter the power supply noise and improve the signal-to-noise ratio of the circuit. Specifically, a second filter circuit can be arranged between the second power terminal 1061 and the first power pin 1014.

[0093] In some specific embodiments, the second filter circuit can be simply composed of two capacitors, that is, a third capacitor 1062 and a fourth capacitor 1063. The third capacitor 1062 and the fourth capacitor 1063 are connected in parallel, one end of the parallel third capacitor 1062 and fourth capacitor 1063 is respectively electrically connected with the first power pin 1014 and the second power terminal 1061, and the other end is electrically connected with the ground terminal. The third capacitor 1062 and the fourth capacitor 1063 constitute a decoupling capacitor combination, which filters the power voltage signal provided by the second power terminal 1061 and improves the power quality. Moreover, the circuit structure can be simplified, the number of circuit elements can be reduced, and the power consumption of the circuit can be reduced, thereby meeting the low power consumption demand of users.

[0094] In the embodiment of the present application, the second filter circuit is electrically connected with the second power terminal 1061, the first power pin 1014 and the ground terminal respectively, so that the noise of the power voltage signal corresponding to the second power terminal 1061 can be filtered, and the signal quality of the power voltage input from the first power pin 1014 to the operational amplifier 101 can be improved.

[0095] The sensor measurement circuit 10 of the embodiment of the present application can be powered by the separate power supply circuit 106, so that it can work and operate independently when other external circuits are in sleep state. In addition, a wake-up circuit can be connected to the output terminal of the operational amplifier 101, which is used to wake up the whole measurement system. The corresponding implementation manner can refer to the means in the prior art, and the embodiment of the present application does not limit this.

[0096] The sensor measurement circuit 10 of the embodiment of the present application can realize the function of short circuit diagnosis, because when the sensitive resistor 1021 is short-circuited, the voltage signal output from the output terminal of the operational amplifier is about the size of the power voltage due to the large closed-loop gain. When the sensitive resistor 1021 is open-circuited, the reverse input terminal of the operational amplifier is suspended, and the output terminal outputs a voltage close to the size of the reference voltage signal, so that the function of open-circuit diagnosis can be realized.

[0097] Figure 2 FIG. 2 is a structure schematic diagram of the sensor measurement circuit 10 provided by the embodiment of the present application, which is a second structure schematic diagram of the sensor measurement circuit 10 provided by the embodiment of the present application. Compared with FIG. 1, the sensor measurement circuit 10 of FIG. 2 further comprises a second filter circuit 106. Figure 1The sensor measurement circuit 10, the sensing circuit 102 includes a sensitive resistor 1021, a first resistor 1022 and a first capacitor 1023, the sensitive resistor 1021 and the first capacitor 1023 are connected in parallel and are respectively connected with the first resistor 1022 and the ground terminal 105, and the first resistor 1022 is connected with the reverse input terminal 1012. The feedback circuit 103 includes a second resistor 1031 and a second capacitor 1032, the second resistor 1031 and the second capacitor 1032 are connected in parallel and are respectively connected with the output terminal 1011 and the reverse input terminal 1012. The reference circuit 104 includes a first power terminal 1041, a third resistor 1042 and a fourth resistor 1043, the third resistor 1042 and the fourth resistor 1043 are connected in series and are respectively connected with the first power terminal 1041 and the ground terminal 105, and a lead wire between the third resistor 1042 and the fourth resistor 1043 is connected with the forward input terminal 1013. The sensor measurement circuit 10 further includes a power supply network 106, the power supply circuit 106 includes a second power terminal 1061, a third capacitor 1062 and a fourth capacitor 1063, the third capacitor 1062 and the fourth capacitor 1063 are connected in parallel and are respectively connected with the second power terminal 1061 and the ground terminal 105. The operational amplifier 101 can further include a first power pin 1014 and a second power pin 1015, the second power pin 1015 is connected with the ground terminal 105, and the first power pin 1014 is connected with the near ground terminal of the parallel third capacitor 1062 and the fourth capacitor 1063. In the sensor measurement circuit 10, the resistance value of the sensitive resistor 1021 changes with the change of the measured parameter, the third resistor 1042 and the fourth resistor 1043 obtain a reference voltage signal by dividing the power voltage signal corresponding to the first power terminal 1041, and input the reference voltage signal into the operational amplifier 101 through the forward input terminal 1013, the operational amplifier 101 can determine the measurement voltage signal corresponding to the measured parameter according to the reference voltage signal and the amplification factor, and output the measurement voltage signal through the output terminal 1011. Referring to Figure 2 The sensor measurement circuit 10 has a simple circuit structure, requires a small number of circuit elements, and in actual application, the current flowing in the circuit can be limited to a low-power current of 100 microamperes (uA), so that the circuit cost and power consumption can be reduced. Figure 2 In the sensitive resistor and the first resistor, a high-frequency noise filtering circuit can also be connected, meeting the user's demand for electromagnetic compatibility (Electro Magnetic Compatibility, EMC).

[0098] In the embodiments of the present application, the sensor measurement circuit 10 measures the temperature parameter as an example to illustrate the measurement principle of the embodiments of the present application. Referring to the following formula (1), the measurement voltage signal V sen of the output end 1011 of the operational amplifier 101 can be calculated according to the resistance values of the sensitive resistor, the first resistor and the second resistor, and the voltage value of the reference voltage signal.

[0099]

[0100] wherein V sen represents the voltage value of the measurement voltage signal, ~V represents the voltage value of the reference voltage signal, R sen represents the resistance value of the sensitive resistor, R1 represents the resistance value of the first resistor, R2 represents the resistance value of the second resistor, and the unit is volt (V). For example, the sensitive resistor is a thermistor, the resistance value changes in the range of 332kΩ-0.65kΩ, the temperature measurement range is -40℃-100℃, the resistance value of the first resistor R1 is 22kΩ, the resistance value of the second resistor R2 is 200kΩ, and the reference voltage signal can be set to 500mV. For the thermistor with the resistance value of 332kΩ, the amplification factor of the sensor measurement circuit 10 is 1.56 times, and the voltage value of the measurement voltage signal output by the circuit is shown in the following formula (2).

[0101] V sen = 0.5 × (200 + 22 + 332.1) / (22 + 332.1) = 0.7824061 (V) (2)

[0102] When the resistance value of the thermistor is 0.6752kΩ, the amplification factor is 9.82 times, and the voltage value of the measurement voltage signal output by the circuit is shown in the following formula (3).

[0103] V sen = 0.5 × (200 + 22 + 0.6752) / (22 + 0.6752) = 4.910104431 (V) (3)

[0104] The corresponding resistance value change range 332kΩ-0.65kΩ and the voltage value range 0.782V-4.91V of the measurement voltage signal when the temperature measurement range is -40℃-100℃ can be obtained, as shown in Table 1.

[0105] Table 1 Temperature-Resistance-Voltage Comparison Table

[0106]

[0107]

[0108] Figure 3is a trend chart of the relationship between the resistance value of the sensitive resistor and the measurement voltage signal provided by the embodiment of the present application, as shown in Figure 3 , the abscissa of curve 1 is temperature, unit is ℃, and the ordinate is the resistance value of the sensitive resistor, unit is kΩ. The abscissa of curve 2 is temperature, unit is ℃, and the ordinate is the voltage value of the measurement voltage signal, unit is V. Referring to curve 1, as the temperature rises, the resistance value of the sensitive resistor gradually decreases, and referring to curve 2, as the temperature rises, the voltage value of the measurement voltage signal gradually increases, and the change of the measurement voltage signal can reflect the change of the resistance value of the sensitive resistor.

[0109] Figure 4 is a schematic diagram of a voltage division method measurement sensor in the prior art, as shown in Figure 4 , NTC represents a thermistor, the voltage division method measurement sensor is used for measuring a temperature parameter, and the constant voltage VDD is divided by the thermistor and the resistor R1 to achieve resistance value measurement of the thermistor. However, when the voltage division method measurement sensor performs grading measurement on resistance values of different orders of magnitude, different voltage division resistors R1 or gain resistors R3 need to be designed for each gear position, and as the number of gear positions increases, the number of resistor elements also increases, and in addition, switches and switch control circuits for isolating different gear positions are needed for switching between different gear positions, and in addition, complex gear switching logic control circuits are also needed for gear switching logic. Figure 4 The voltage division method measurement sensor has the problem of complex circuit for grading measurement on resistance values of different orders of magnitude. Since the power consumption of the circuit increases with the increase in the number of circuit elements, the grading measurement method will result in high circuit power consumption.

[0110] Figure 5 is a schematic diagram of a Wheatstone bridge measurement sensor in the prior art, as shown in Figure 5 , the Wheatstone bridge measurement sensor also uses the voltage division method to measure the change of the resistance value to achieve measurement of the measured parameter. The Wheatstone bridge measurement sensor is driven by a voltage source, and in the case where the measured parameter changes, the resistance value of the resistor Rt on the bridge arm changes, thereby destroying the balance of the bridge, outputting a differential mode signal to the input end of the operational amplifier, and the operational amplifier can obtain the resistance value change amount of the resistor Rt by adjusting and converting the size of the differential mode signal, and further convert the size of the measured parameter. It should be noted that the sensor can be the resistor Rt or the entire bridge. However, when the Wheatstone bridge measurement sensor performs grading measurement on resistance values of different orders of magnitude, the bridge still needs to be graded, specifically, different resistance values need to be set for the resistor RW1 on the bridge arm for each gear position, and at the same time, switches and switch control circuits for different gear positions, and gear switching logic control circuits are also introduced into the measurement circuit. Therefore, as shown in Figure 4The Wen-Tsai bridge measurement sensor has the problem of circuit complexity in the way of grading measurement of resistance values of different orders of magnitude. Since the power consumption of the circuit increases with the increase in the number of circuit elements, the circuit power consumption of the Wen-Tsai bridge measurement sensor is high.

[0111] Figure 6 is a circuit schematic diagram of a constant current method measurement sensor in the prior art, as Figure 6 shown, the left side of the constant current method measurement sensor can be connected to a sensor or a sensitive element, such as a temperature sensor. The circuit includes a constant current source, which can provide a stable power supply for the sensor through the output end on the left side of the circuit, and receive the voltage signal of the sensor through the input end on the left side of the circuit, and then send the measurement signal into an analog-to-digital conversion chip for processing. The resistance change of the sensor can be calculated according to the voltage signal and the current value of the known constant current source, and then the size of the measured parameter can be converted. However, when grading measurement of resistance values of different orders of magnitude is performed, different gear switches and switch control circuits, gear switching logic control circuits are introduced into the measurement circuit, which makes the circuit complex and the control requirement high.

[0112] It should be noted that when grading measurement of resistance values of different orders of magnitude is performed, the resistance value at the gear switching position is limited by the gear switching, and the resolution of the measurement voltage signal obtained is low, which leads to the problem of low measurement accuracy when the subsequent circuit converts the change amount of the measured parameter according to the measurement voltage signal. The sensor measurement circuit 10 of the present application embodiment is different from the way of grading measurement of resistance values of different orders of magnitude by the constant current method or the voltage division method. The resistance value of the induction circuit is taken as part of the amplification circuit, so that the amplification multiple of the circuit is associated with the resistance value of the induction circuit. The way of attenuation and amplification at different resistance values is ingeniously utilized to avoid the problem of low resolution at some resistance values caused by the cross-order of magnitude, which leads to poor accuracy.

[0113] The sensor measurement circuit 10 of the present application embodiment has little difference in measurement accuracy compared with the circuit of the constant current method grading measurement, but is simplified in the circuit, and is more suitable for application in industrial vehicles and other use scenarios. It should be noted that there are many factors affecting the measurement accuracy of the entire circuit, which depends on the weak link of the circuit. Under the same conditions, the sensor measurement circuit 10 of the present application embodiment has a simpler circuit structure than the constant current method grading measurement circuit when measuring resistance values of cross orders of magnitude, requires fewer circuit elements, and has lower overall circuit power consumption. For example, in actual application, the output interval of the measurement voltage signal of the sensor measurement circuit 10 of the present application embodiment is 0.8V-4.9V, and the constant current method grading measurement circuit can divide the output interval into N 0-5V. If the output intervals of the two are consistent, the circuit of the sensor measurement circuit 10 of the present application embodiment is simple, which can reduce the circuit cost and meet the low power consumption demand of users.

[0114] Compared with the circuit for measuring in sections by the voltage division method, the sensor measurement circuit 10 of the embodiment of the present application does not need a high-precision reference voltage, is less affected by external electromagnetic interference, low noise and other interference, and directly outputs an operational amplifier, which has ideal output characteristics and is less affected by the back-end circuit.

[0115] The embodiment of the present application also provides a sensor including the sensor measurement circuit 10 provided by the foregoing embodiment. The sensor can be a temperature sensor, a photosensitive sensor or the like, and is used for measuring physical quantities such as temperature and light intensity. Compared with the way of measuring resistors of different orders of magnitude by grading in the prior art constant current method or voltage division method, the sensor measurement circuit 10 in the sensor has a simple circuit structure and uses fewer circuit elements, and therefore, the power consumption of the circuit can be reduced, the occupation of power supply resources of the sensor can be reduced, and the cost of the sensor can be reduced.

[0116] The embodiment of the present application also provides a vehicle including the sensor described in the foregoing embodiment. The sensor can be a temperature sensor in the vehicle and is used for measuring the temperature of components such as an engine. By using the sensor of the embodiment of the present application, the sensor measurement circuit is simple in structure and low in power consumption, the sensor is low in cost and high in practicability.

[0117] It should be noted that, in the present document, the relationship terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0118] Each of the embodiments in the present specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the difference from other embodiments. The above only describes the preferred embodiments of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application are included in the protection scope of the present application.

[0119] It should be noted that the acquisition of various data related processes in the embodiments of the present application are performed under the premise of complying with the corresponding data protection regulations and policies of the country where the data is located, and under the condition of obtaining authorization from the owner of the corresponding device.

Claims

1. A sensor measurement circuit, characterized by The sensor measurement circuit comprises: an operational amplifier, a sensitive circuit, a feedback circuit, a reference circuit and a ground terminal; the feedback circuit is electrically connected with the output terminal and the reverse input terminal of the operational amplifier respectively; the sensitive circuit is electrically connected with the reverse input terminal and the ground terminal respectively; wherein the resistance value of the sensitive circuit changes with the change of the measured parameter; the reference circuit is electrically connected with the forward input terminal of the operational amplifier, for inputting a reference voltage signal to the operational amplifier; the operational amplifier is used for outputting a measurement voltage signal corresponding to the measured parameter according to the reference voltage signal and the amplification multiple.

2. The sensor measurement circuit of claim 1, wherein, The sensitive circuit comprises: a sensitive resistor; 3. The sensor measurement circuit of claim 2, wherein, the sensitive resistor is electrically connected with the ground terminal and the reverse input terminal respectively. The sensitive circuit further comprises:

4. The sensor measurement circuit of claim 1, wherein, a first resistor; the first resistor is arranged between the sensitive resistor and the reverse input terminal, and is electrically connected with the sensitive resistor and the reverse input terminal respectively. The feedback circuit comprises:

5. The sensor measurement circuit of claim 1, wherein, a second resistor and a first filter circuit; the second resistor is electrically connected with the output terminal and the reverse input terminal respectively; the first filter circuit is electrically connected with the output terminal and the reverse input terminal respectively, and is connected in parallel with the second resistor.

6. The sensor measurement circuit of claim 5, wherein, The reference circuit comprises: a first power terminal and a voltage dividing circuit; the voltage dividing circuit is electrically connected with the first power terminal and the ground terminal respectively, for dividing the power voltage signal corresponding to the first power terminal to obtain the reference voltage signal; 7. The sensor measurement circuit of claim 1, wherein, the voltage dividing circuit is further electrically connected with the forward input terminal, for inputting the reference voltage signal to the operational amplifier through the forward input terminal. The voltage dividing circuit comprises: a third resistor and a fourth resistor; one end of the third resistor is electrically connected with the first power terminal, and the other end of the third resistor is electrically connected with the fourth resistor and the forward input terminal respectively; 8. The sensor measurement circuit of claim 7, wherein, the end of the fourth resistor connected with the third resistor is further electrically connected with the forward input terminal, and the other end of the fourth resistor is electrically connected with the ground terminal. Further comprising:

9. A sensor, characterized by a power supply circuit; the operational amplifier further comprises a first power pin and a second power pin; 10. A vehicle characterized by comprising: the power supply circuit is electrically connected with the first power pin; the second power pin is electrically connected with the ground terminal. The power supply circuit comprises: a second power terminal and a second filter circuit; the second filter circuit is electrically connected with the second power terminal, the first power pin and the ground terminal respectively. The sensor measurement circuit comprises any one of claims 1 to 8. The sensor comprises claim 9.

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