A temperature compensation module for an eddy current sensor

Abstract

The application provides a temperature compensation module and method of an eddy current sensor, comprising a temperature detection unit, a temperature difference judgment unit and a temperature compensation unit; the temperature detection unit is used for detecting the temperature of the eddy current sensor based on a detection frequency, and generating a real-time temperature detection value; the temperature difference judgment unit is used for receiving the real-time temperature detection value, and generating a temperature difference indication signal according to the change amount of the real-time temperature detection value; and the temperature compensation unit is used for receiving the temperature difference indication signal and the real-time temperature detection value, and generating a real-time compensation value according to the temperature difference indication signal and the real-time temperature detection value, which is used for compensating the angle measurement value of the eddy current sensor. The application can avoid the jump of the compensation output caused by the sudden change of the temperature, generate smooth and stable compensation output, avoid the distortion and error of the angle measurement data, improve the detection precision, and meet the requirements of long-term stable monitoring in the actual application scene.

Description

Technical Field

[0001] This application relates to the field of sensor technology, and in particular to a temperature compensation module for an eddy current sensor. Background Technology

[0002] In industrial automation, power equipment condition monitoring, aerospace attitude control and other scenarios, eddy current sensors are widely used for real-time detection of various angle, position and other parameters due to their advantages such as non-contact measurement, fast response speed and strong anti-interference ability.

[0003] Currently, eddy current sensors commonly suffer from significant temperature drift in practical applications. When the ambient temperature rises from -40℃ to a wide temperature range of 125℃ or even 150℃, the resistivity of the sensor's internal coil increases linearly with temperature, causing a shift in the coil's equivalent impedance. This leads to a deviation in the correspondence between the eddy current sensor's output signal and the actual angle, with measurement errors reaching over 8% of full scale. Therefore, eddy current sensors require a built-in temperature compensation module to correct the output signal, offsetting temperature drift and improving the sensor's detection accuracy.

[0004] However, in practical applications, eddy current sensors face various complex and abnormal operating conditions. Under short-term thermal shock conditions such as short-term overload, sudden changes in ambient temperature, and local heat source impact, sudden temperature changes can cause abrupt changes in the compensation output, even exceeding the temperature compensation's adaptation range. This leads to distortion and errors in angle measurement data, affecting detection accuracy and failing to meet the requirements for long-term stable monitoring in practical applications. Summary of the Invention

[0005] In view of the above problems, this application is made to provide a temperature compensation module and method for an eddy current sensor, which can avoid the compensation output jump caused by sudden temperature changes, generate a smooth and stable compensation output, avoid distortion and error of angle measurement data, improve detection accuracy, and meet the requirements of long-term stable monitoring in practical application scenarios.

[0006] To achieve the above objectives, in a first aspect, this application provides a temperature compensation module for an eddy current sensor, including a temperature detection unit, a temperature difference judgment unit, and a temperature compensation unit.

[0007] The temperature detection unit is used to detect the temperature of the eddy current sensor based on the detection frequency and generate real-time temperature detection values.

[0008] The temperature difference judgment unit is used to receive real-time temperature detection values ​​and generate a temperature difference indication signal based on the change in the real-time temperature detection values.

[0009] The temperature compensation unit is used to receive the temperature difference indication signal and the real-time temperature detection value, and generate a real-time compensation value based on the temperature difference indication signal and the real-time temperature detection value to compensate the angle measurement value of the eddy current sensor.

[0010] Furthermore, the temperature difference judgment unit is further configured as follows:

[0011] When the change in the real-time temperature detection value is not greater than the preset change threshold, a first-level temperature difference indication signal is generated.

[0012] When the change in the real-time temperature detection value exceeds a preset change threshold, a second-level temperature difference indication signal is generated.

[0013] Furthermore, the temperature compensation unit is further configured as follows:

[0014] When the temperature compensation unit receives the first level temperature difference indication signal, the temperature compensation unit calculates the real-time compensation value based on the real-time temperature detection value and the preset compensation function. The preset compensation function is a fitting function of the temperature detection value and the compensation value.

[0015] When the temperature compensation unit receives a second-level temperature difference indication signal, it adds a constant preset adjustment value to the compensation value before the sudden change, thereby generating a real-time compensation value.

[0016] Furthermore, the temperature compensation unit is further configured as follows:

[0017] When the temperature difference between the real-time temperature detection value and the temperature detection value before the sudden change is within the preset change threshold, the addition of a constant preset adjustment value to the compensation value before the sudden change stops, and the real-time compensation value is calculated based on the real-time temperature detection value and the preset compensation function.

[0018] Furthermore, the temperature difference judgment unit includes a temperature difference calculation subunit and a comparison judgment subunit;

[0019] The temperature difference calculation subunit is used to receive real-time temperature detection values ​​and generate the change in real-time temperature detection values ​​based on the difference between the real-time temperature detection values ​​at two adjacent detection times.

[0020] The comparison and judgment subunit is used to receive the change in the real-time temperature detection value and the preset change threshold, compare the change in the real-time temperature detection value with the preset change threshold, and generate a temperature difference indication signal.

[0021] Furthermore, the temperature detection unit includes a startup circuit, a current generation circuit, a subtraction circuit, and an analog-to-digital conversion circuit;

[0022] A startup circuit is used to generate an initial voltage based on the power supply voltage.

[0023] The current generating circuit is used to receive the initial voltage and generate PTAT current and CTAT current according to the power supply voltage;

[0024] The subtraction circuit receives the PTAT current and CTAT current, and generates a detection voltage based on the current difference between the PTAT current and CTAT current to indicate the temperature of the eddy current sensor.

[0025] The analog-to-digital converter circuit performs analog-to-digital conversion on the detection voltage based on the detection frequency to generate real-time temperature detection values.

[0026] Furthermore, the current generating circuit includes a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, an eighth transistor, a ninth transistor, a first capacitor, a first resistor, and a second resistor;

[0027] The gates of the first transistor, the second transistor, and the third transistor are connected together and to an initial voltage. The source of the first transistor is connected to a reference ground via a first resistor. The sources of the second and third transistors are also connected to the reference ground. The drain of the first transistor is connected to the drain of the fourth transistor. The source of the fourth transistor is connected to the drain of the seventh transistor. The gate of the fourth transistor is connected to the gates of the fifth and sixth transistors and their drains. The gate of the seventh transistor is connected to the gate of the eighth transistor. The sources of the seventh and eighth transistors are connected to the power supply voltage. The drain of the second transistor is connected to the drain of the fifth transistor, the gate of the ninth transistor, and the first terminal of the first capacitor, generating a PTAT current. The source of the fifth transistor is connected to the drain of the eighth transistor. The drain of the ninth transistor is used to generate a CTAT current. The source of the ninth transistor is connected to the first terminal of the second resistor. The second terminal of the second resistor, the second terminal of the first capacitor, and the source of the third transistor are connected to the reference ground. The drain of the third transistor is connected to the drain of the sixth transistor. The source of the sixth transistor is connected to the power supply voltage.

[0028] Furthermore, the subtraction circuit includes a tenth transistor, an eleventh transistor, and a third resistor;

[0029] The source of the tenth transistor is connected to the power supply voltage, the gate of the tenth transistor is connected to the gate of the eighth transistor, the drain of the tenth transistor is connected to the source of the eleventh transistor and the drain of the ninth transistor, the gate of the eleventh transistor is connected to the gate of the fifth transistor, the drain of the eleventh transistor is connected to the first terminal of the third resistor and generates a detection voltage, and the second terminal of the third resistor is connected to the reference ground.

[0030] Furthermore, the startup circuit includes a twelfth transistor, a thirteenth transistor, a fourteenth transistor, and a second capacitor;

[0031] The gate of the twelfth transistor is connected to the source of the twelfth transistor, the second terminal of the second capacitor, and the reference ground. The drain of the twelfth transistor is connected to the drain of the thirteenth transistor and the gate of the first transistor, and generates an initial voltage. The gate of the thirteenth transistor is connected to the drain of the fourteenth transistor and the first terminal of the second capacitor. The source of the thirteenth transistor is connected to the source of the fourteenth transistor and the power supply voltage. The gate of the fourteenth transistor is connected to the gate of the seventh transistor.

[0032] Secondly, this application also provides a temperature compensation method for an eddy current sensor, which utilizes the aforementioned temperature compensation module for temperature compensation. The temperature compensation method includes:

[0033] The temperature detection unit controls the temperature of the eddy current sensor based on the detection frequency and generates a real-time temperature detection value.

[0034] The temperature difference judgment unit generates a temperature difference indication signal based on the change in the real-time temperature detection value;

[0035] The temperature compensation control unit generates a real-time compensation value based on the temperature difference indication signal and the real-time temperature detection value, which is used to compensate for the angle measurement value of the eddy current sensor.

[0036] The beneficial effects of this application are:

[0037] (1) This application provides a temperature compensation module for an eddy current sensor, which includes a temperature difference judgment unit and a temperature compensation unit. When the change in the real-time temperature detection value is not greater than a preset change threshold, the temperature compensation unit calculates the real-time compensation value according to a preset compensation function. When the change in the real-time temperature detection value is greater than the preset change threshold, the temperature compensation unit adds a constant preset adjustment value to the compensation value before the sudden change, so as to avoid the compensation output jump caused by the sudden temperature change, generate a smooth and stable compensation output, avoid distortion and error of angle measurement data, improve detection accuracy, and meet the requirements of long-term stable monitoring in actual application scenarios.

[0038] (2) This application also provides a temperature detection unit that uses the difference between PTAT current and CTAT current to generate a detection signal, thereby improving temperature sensitivity; at the same time, a single negative feedback loop is used to keep PTAT current and CTAT current stable, thereby reducing the volume of the temperature detection unit and further improving the temperature detection accuracy, thus providing a basis for subsequent temperature compensation improvement. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A structural block diagram of the temperature compensation module provided in this application;

[0041] Figure 2 A structural block diagram of the temperature difference judgment unit provided in this application;

[0042] Figure 3 A circuit diagram of the temperature detection module provided in this application;

[0043] Figure 4 A flowchart of the temperature compensation method provided in this application. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “said,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. “Multiple” generally includes at least two, but does not exclude the inclusion of at least one.

[0046] This application provides a temperature compensation module and method for an eddy current sensor. It includes a temperature difference judgment unit and a temperature compensation unit. When the change in the real-time temperature detection value is no greater than a preset change threshold, the temperature compensation unit calculates a real-time compensation value based on a preset compensation function. When the change in the real-time temperature detection value is greater than the preset change threshold, the temperature compensation unit adds a constant preset adjustment value to the compensation value before the sudden change. This avoids jumps in the compensation output caused by sudden temperature changes, resulting in a smooth and stable compensation output. This prevents distortion and errors in angle measurement data, improves detection accuracy, and meets the requirements for long-term stable monitoring in practical application scenarios.

[0047] Furthermore, this application also provides a temperature detection unit that generates a detection signal by subtracting the PTAT current and CTAT current to improve temperature sensitivity; at the same time, it adopts a single negative feedback loop to keep the PTAT current and CTAT current stable, reducing the size of the temperature detection unit and further improving the temperature detection accuracy, thus providing a basis for subsequent temperature compensation improvements.

[0048] The present application will be further described below with reference to the accompanying drawings and specific embodiments.

[0049] In some embodiments of this application, such as Figure 1 As shown, this application provides a temperature compensation module for an eddy current sensor. The temperature compensation module for the eddy current sensor includes a temperature detection unit, a temperature difference judgment unit, and a temperature compensation unit.

[0050] The temperature detection unit is used to detect the temperature of the eddy current sensor based on the detection frequency and generate real-time temperature detection values.

[0051] The temperature difference judgment unit is used to receive real-time temperature detection values ​​and generate a temperature difference indication signal based on the change in the real-time temperature detection values.

[0052] Among them, a temperature difference indication signal is generated based on the change in the real-time temperature detection value, including:

[0053] When the change in the real-time temperature detection value is not greater than the preset change threshold, a first-level temperature difference indication signal is generated to indicate that no short-term thermal shock has occurred in the application scenario of the eddy current sensor. At this time, the temperature compensation module can generate a smooth and stable compensation output.

[0054] When the change in the real-time temperature detection value exceeds the preset change threshold, a second-level temperature difference indication signal is generated to indicate that a short-term thermal shock has occurred in the application scenario of the eddy current sensor. If temperature compensation is performed at this time, it will cause the compensation output to jump, or even exceed the temperature compensation adaptation range, resulting in distortion and misjudgment of the angle measurement data.

[0055] The temperature compensation unit is used to receive the temperature difference indication signal and the real-time temperature detection value, and generate a real-time compensation value based on the temperature difference indication signal and the real-time temperature detection value to compensate the angle measurement value of the eddy current sensor.

[0056] Among them, real-time compensation values ​​are generated based on the temperature difference indication signal and the real-time temperature detection value, including:

[0057] Optionally, when the temperature compensation unit receives a temperature difference indication signal of the first level, the temperature compensation unit calculates a real-time compensation value based on the real-time temperature detection value and a preset compensation function, wherein the preset compensation function is a fitting function of the temperature detection value and the compensation value.

[0058] Specifically, compensation values ​​for multiple temperature detection values ​​within the range of the eddy current sensor are obtained in advance, and polynomial fitting is performed to obtain a preset compensation function within the range of the eddy current sensor.

[0059] When the temperature compensation unit receives the second-level temperature difference indication signal, it adds a constant preset adjustment value to the compensation value before the sudden change, generating a real-time compensation value until the short-term thermal shock disappears.

[0060] In applications where eddy current sensors are used, short-term thermal shocks are considered negligible due to their short duration. Instead, a constant preset adjustment value is added to the compensation value before the abrupt change to meet the compensation requirements. The specific preset adjustment value is selected based on the smoothness of the thermal shock.

[0061] Furthermore, when the temperature difference between the real-time temperature detection value and the temperature detection value before the sudden change is within a preset change threshold, the addition of a constant preset adjustment value to the compensation value before the sudden change is stopped, and the real-time compensation value is calculated based on the real-time temperature detection value and the preset compensation function.

[0062] This embodiment of the application includes a temperature difference judgment unit and a temperature compensation unit. When the change in the real-time temperature detection value is not greater than a preset change threshold, the temperature compensation unit calculates the real-time compensation value according to a preset compensation function. When the change in the real-time temperature detection value is greater than the preset change threshold, the temperature compensation unit adds a constant preset adjustment value to the compensation value before the sudden change, so as to avoid the compensation output jump caused by the sudden temperature change, generate a smooth and stable compensation output, avoid distortion and error of angle measurement data, improve detection accuracy, and meet the requirements of long-term stable monitoring in practical application scenarios.

[0063] In some embodiments of this application, such as Figure 2 As shown, the temperature difference judgment unit includes a temperature difference calculation subunit and a comparison judgment subunit, wherein:

[0064] The temperature difference calculation subunit is used to receive real-time temperature detection values ​​and generate the change in real-time temperature detection values ​​based on the difference between the real-time temperature detection values ​​at two adjacent detection times; where two adjacent detection times refer to the current detection time and the previous detection time.

[0065] The comparison and judgment subunit receives the change in the real-time temperature detection value and a preset change threshold, compares the change in the real-time temperature detection value with the preset change threshold, and generates a temperature difference indication signal. The temperature difference indication signal includes a first-level temperature difference indication signal and a second-level temperature difference indication signal. The first-level temperature difference indication signal indicates that the change in the temperature detection value is not greater than the preset change threshold, and the second-level temperature difference indication signal indicates that the change in the temperature detection value is greater than the preset change threshold.

[0066] In some embodiments of this application, a temperature detection unit is provided, which employs a single negative feedback loop and a subtraction circuit to reduce the size of the temperature detection unit while improving the temperature detection accuracy. This unit is suitable for integration into an eddy current sensor to achieve subsequent temperature compensation.

[0067] like Figure 3 As shown, the temperature detection unit includes a startup circuit, a current generation circuit, a subtraction circuit, and an analog-to-digital conversion circuit. Specifically:

[0068] The startup circuit is used to generate an initial voltage Vint based on the power supply voltage VDD.

[0069] The current generating circuit is used to receive the initial voltage and generate a PTAT (proportional to absolute temperature) current Ip and a CTAT (inversely proportional to absolute temperature) current Ic according to the power supply voltage VDD.

[0070] The subtraction circuit is used to receive the PTAT current Ip and the CTAT current Ic. Based on the current difference between the PTAT current Ip and the CTAT current Ic, it generates a detection voltage Vtemp, which is used to indicate the temperature of the eddy current sensor.

[0071] The analog-to-digital converter circuit performs analog-to-digital conversion on the detection voltage Vtemp based on the detection frequency to generate a real-time temperature detection value.

[0072] Furthermore, the current generating circuit includes a first transistor M1, a second transistor M2, a third transistor M3, a fourth transistor M4, a fifth transistor M5, a sixth transistor M6, a seventh transistor M7, an eighth transistor M8, a ninth transistor M9, a first capacitor C1, a first resistor R1, and a second resistor R2.

[0073] The gates of the first transistor M1, the second transistor M2, and the third transistor M3 are connected and connected to the initial voltage Vint. The source of the first transistor M1 is connected to the reference ground VSS through the first resistor R1. The sources of the second transistor M2 and the third transistor M3 are also connected to the reference ground VSS. The drain of the first transistor M1 is connected to the drain of the fourth transistor M4. The source of the fourth transistor M4 is connected to the drain of the seventh transistor M7. The gate of the fourth transistor M4 is connected to the gate of the fifth transistor M5, the gate of the sixth transistor M6, and the drain of the sixth transistor M6. The gate of the seventh transistor M7 is connected to the gate of the eighth transistor M8. The source of the seventh transistor M7... The source of the eighth transistor M8 is connected to the power supply voltage VDD; the drain of the second transistor M2 is connected to the drain of the fifth transistor M5, the gate of the ninth transistor M9, and the first terminal of the first capacitor C1, and generates the PTAT current Ip; the source of the fifth transistor M5 is connected to the drain of the eighth transistor M8; the drain of the ninth transistor M9 is used to generate the CTAT current Ic; the source of the ninth transistor M9 is connected to the first terminal of the second resistor R2, the second terminal of the second resistor R2, the second terminal of the first capacitor C1, and the source of the third transistor M3 are connected to the reference ground VSS; the drain of the third transistor M3 is connected to the drain of the sixth transistor M6, and the source of the sixth transistor M6 is connected to the power supply voltage VDD.

[0074] Among them, the first transistor M1, the second transistor M2, the third transistor M3, and the ninth transistor M9 are NMOS transistors, and the fourth transistor M4, the fifth transistor M5, the sixth transistor M6, the seventh transistor M7, and the eighth transistor M8 are PMOS transistors.

[0075] In the current generation circuit, the PTAT current is a current whose magnitude increases with increasing temperature, which can be achieved using two transistors, M1 and M2, operating in a subthreshold state. In the subthreshold state, the gate-source voltage difference ∆VGS between transistors M1 and M2 exhibits a direct proportionality to temperature; therefore, the temperature-proportional PTAT current Ip can be generated using this gate-source voltage difference ∆VGS. Based on this principle, transistors M1 and M2 are biased with the same gate voltage VGS and drain current. The current density ratio of transistors M1 and M2 is N1:1. Transistors M7 and M8 form a current mirror. The first resistor R1 is the source series resistor of transistor M1, and the voltage across it is the gate-source voltage difference ∆VGS between transistors M1 and M2. With the drain currents flowing through transistors M1 and M2 matched and balanced, the PTAT current Ip can be expressed as:

[0076]

[0077] Where k is the Boltzmann constant, T is the temperature, and q is the electron charge.

[0078] The generated PTAT current Ip is mirrored to the subtraction circuit through a current mirror circuit composed of the seventh transistor M7, the eighth transistor M8, and the tenth transistor M10.

[0079] In the current generation circuit, the CTAT current is a current whose magnitude decreases with increasing temperature. This can be achieved by utilizing the temperature-dependent negative correlation of the gate-source voltage VGS of the first transistor M1 or the second transistor M2. As the temperature increases, the degradation of mobility and the reduction of the bandgap within the first transistor M1 or the second transistor M2 lead to a decrease in the threshold voltage. This causes the gate-source voltage VGS of the first transistor M1 or the second transistor M2 to exhibit a temperature-dependent negative correlation with temperature in the subthreshold operating state. Therefore, the CTAT current Ic can be expressed as:

[0080]

[0081] The generated CTAT current Ic is connected to the subtraction module and flows out of the subtraction module to the drain of the ninth transistor M9.

[0082] In the current generation circuit, in order to ensure the stability of PTAT current Ip and CTAT current Ic, a single negative feedback loop is added. The gate-source voltage of the first transistor M1 and the second transistor M2 is adjusted by the ninth transistor M9 to achieve the stability of PTAT current Ip and CTAT current Ic.

[0083] Specifically, a single negative feedback loop includes transistor M9 (ninth), transistor M3 (third), transistor M4 (fourth), transistor M5 (fifth), and transistor M6 (sixth). When the PTAT current Ip is unstable, the change in the gate-source voltage VGS causes a change in the current flowing through transistor M3. After being mirrored by transistors M4, M5, and M6, the drain currents of transistors M1 and M2 are adjusted, making the drain currents of transistors M1 and M2 matched and balanced, thereby suppressing changes in the PTAT current Ip and stabilizing the PTAT current Ip. Similarly, when the CTAT current Ic is unstable, the change in the gate-source voltage VGS across the second resistor R2 causes a change in the current flowing through transistor M3. After being mirrored by transistors M4, M5, and M6, the drain currents of transistors M1 and M2 are matched and balanced, stabilizing the gate-source voltage VGS, suppressing changes in the gate-source voltage VGS, and thus stabilizing the CTAT current Ic. Finally, after adjustment by the negative feedback loop, the drain currents flowing through the first transistor M1 and the second transistor M2 are equal, and the current generation circuit reaches a matched balance state. At this time, the source of the ninth transistor M9 generates the gate-source voltage VGS, the PTAT current Ip shows a positive temperature correlation, and the CTAT characteristic shows a negative temperature correlation.

[0084] The current generation circuit of this application, on the one hand, uses a single negative feedback loop to keep the PTAT current Ip and CTAT current Ic stable, reducing the number of transistors in the control loop and reducing the size of the temperature detection unit, making it suitable for integration into the eddy current sensor. On the other hand, it generates the PTAT current Ip and CTAT current Ic based on the temperature stability of the eddy current sensor, thereby improving the temperature detection accuracy.

[0085] Furthermore, the subtraction circuit includes the tenth transistor M10, the eleventh transistor M11, and the third resistor R3.

[0086] The source of the tenth transistor M10 is connected to the power supply voltage VDD, the gate of the tenth transistor M10 is connected to the gate of the eighth transistor M8, the drain of the tenth transistor M10 is connected to the source of the eleventh transistor M11 and the drain of the ninth transistor M9, the gate of the eleventh transistor M11 is connected to the gate of the fifth transistor M5, the drain of the eleventh transistor M11 is connected to the first terminal of the third resistor R3 and generates the detection voltage Vtemp, and the second terminal of the third resistor R3 is connected to the reference ground VSS.

[0087] Among them, the tenth transistor M10 and the eleventh transistor M11 are PMOS transistors.

[0088] In the subtraction circuit, to achieve high temperature sensitivity at the output of the temperature detection unit, the generated PTAT current Ip and CTAT current Ic are subtracted, resulting in the following output current:

[0089]

[0090] Wherein, N2 is the scaling factor of the current mirror composed of the tenth transistor M10 and the eighth transistor M8.

[0091] The output current Itemp is output to resistor R3 via the eleventh transistor M11, and then converted into a detection voltage Vtemp by resistor R3. The eleventh transistor M11 is used to isolate the detection voltage from the drain voltage of the ninth transistor M9, thereby expanding the operating range of the CTAT component. The detection voltage Vtemp can be expressed as:

[0092]

[0093] Furthermore, the startup circuit includes a twelfth transistor M12, a thirteenth transistor M13, a fourteenth transistor M14, and a second capacitor C2.

[0094] The gate of the twelfth transistor M12 is connected to the source of the twelfth transistor M12, the second terminal of the second capacitor C2, and the reference ground VSS. The drain of the twelfth transistor M12 is connected to the drain of the thirteenth transistor M13 and the gate of the first transistor M1, and generates the initial voltage Vint. The gate of the thirteenth transistor M13 is connected to the drain of the fourteenth transistor M14 and the first terminal of the second capacitor C2. The source of the thirteenth transistor M13 is connected to the source of the fourteenth transistor M14 and the power supply voltage VDD. The gate of the fourteenth transistor M14 is connected to the gate of the seventh transistor M7.

[0095] When the startup circuit starts, it controls the thirteenth transistor M13 to turn on, providing the initial voltage Vint to the first transistor M1 and the second transistor M2, and controlling the generation of PTAT current Ip. When the fourteenth transistor M14 detects the gate voltage of the seventh transistor M7 and turns on, the gate of the thirteenth transistor M13 is pulled up to the power supply voltage, the thirteenth transistor M13 turns off, and the startup circuit stops working.

[0096] In this embodiment of the application, the temperature detection unit generates a detection signal by subtracting the PTAT current and CTAT current, thereby improving temperature sensitivity. At the same time, a single negative feedback loop is used to keep the PTAT current and CTAT current stable, reducing the size of the temperature detection unit and further improving the temperature detection accuracy, thus providing a basis for subsequent temperature compensation improvements.

[0097] In another embodiment of this application, a temperature compensation method for an eddy current sensor is also provided. This temperature compensation method utilizes the aforementioned temperature compensation module for temperature compensation, such as... Figure 4 As shown, the temperature compensation method includes:

[0098] The temperature detection unit controls the temperature of the eddy current sensor based on the detection frequency and generates a real-time temperature detection value.

[0099] The temperature difference judgment unit generates a temperature difference indication signal based on the change in the real-time temperature detection value;

[0100] The temperature compensation control unit generates a real-time compensation value based on the temperature difference indication signal and the real-time temperature detection value, which is used to compensate for the angle measurement value of the eddy current sensor.

[0101] Furthermore, the temperature difference judgment unit generates a temperature difference indication signal based on the change in the real-time temperature detection value, including:

[0102] When the change in the real-time temperature detection value is not greater than the preset change threshold, a first-level temperature difference indication signal is generated.

[0103] When the change in the real-time temperature detection value exceeds a preset change threshold, a second-level temperature difference indication signal is generated.

[0104] Furthermore, the temperature compensation unit generates a real-time compensation value based on the temperature difference indication signal and the real-time temperature detection value, which is used to compensate for the angle measurement value of the eddy current sensor, including:

[0105] When the temperature compensation unit receives the first level temperature difference indication signal, the temperature compensation unit calculates the real-time compensation value according to the preset compensation function, which is a fitting function of the temperature detection value and the compensation value.

[0106] When the temperature compensation unit receives a second-level temperature difference indication signal, it adds a constant preset adjustment value to the compensation value before the sudden change, thereby generating a real-time compensation value.

[0107] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A temperature compensation module for an eddy current sensor, characterized in that, It includes a temperature detection unit, a temperature difference judgment unit, and a temperature compensation unit; The temperature detection unit is used to detect the temperature of the eddy current sensor based on the detection frequency and generate real-time temperature detection values. The temperature difference judgment unit is used to receive real-time temperature detection values ​​and generate a temperature difference indication signal based on the change in the real-time temperature detection values. The temperature compensation unit is used to receive the temperature difference indication signal and the real-time temperature detection value, and generate a real-time compensation value based on the temperature difference indication signal and the real-time temperature detection value to compensate the angle measurement value of the eddy current sensor.

2. The temperature compensation module according to claim 1, characterized in that, The temperature difference judgment unit is further configured as follows: When the change in the real-time temperature detection value is not greater than the preset change threshold, a first-level temperature difference indication signal is generated. When the change in the real-time temperature detection value exceeds a preset change threshold, a second-level temperature difference indication signal is generated.

3. The temperature compensation module according to claim 2, characterized in that, The temperature compensation unit is further configured as follows: When the temperature compensation unit receives the first level temperature difference indication signal, the temperature compensation unit calculates the real-time compensation value based on the real-time temperature detection value and the preset compensation function. The preset compensation function is a fitting function of the temperature detection value and the compensation value. When the temperature compensation unit receives a second-level temperature difference indication signal, it adds a constant preset adjustment value to the compensation value before the sudden change, thereby generating a real-time compensation value.

4. The temperature compensation module according to claim 3, characterized in that, The temperature compensation unit is further configured as follows: When the temperature difference between the real-time temperature detection value and the temperature detection value before the sudden change is within the preset change threshold, the addition of a constant preset adjustment value to the compensation value before the sudden change stops, and the real-time compensation value is calculated based on the real-time temperature detection value and the preset compensation function.

5. The temperature compensation module according to claim 1, characterized in that, The temperature difference judgment unit includes a temperature difference calculation subunit and a comparison judgment subunit; The temperature difference calculation subunit is used to receive real-time temperature detection values ​​and generate the change in real-time temperature detection values ​​based on the difference between the real-time temperature detection values ​​at two adjacent detection times. The comparison and judgment subunit is used to receive the change in the real-time temperature detection value and the preset change threshold, compare the change in the real-time temperature detection value with the preset change threshold, and generate a temperature difference indication signal.

6. The temperature compensation module according to claim 1, characterized in that, The temperature detection unit includes a startup circuit, a current generation circuit, a subtraction circuit, and an analog-to-digital conversion circuit; A startup circuit is used to generate an initial voltage based on the power supply voltage. The current generating circuit is used to receive the initial voltage and generate PTAT current and CTAT current according to the power supply voltage; The subtraction circuit receives the PTAT current and CTAT current, and generates a detection voltage based on the current difference between the PTAT current and CTAT current to indicate the temperature of the eddy current sensor. The analog-to-digital converter circuit performs analog-to-digital conversion on the detection voltage based on the detection frequency to generate real-time temperature detection values.

7. The temperature compensation module according to claim 6, characterized in that, The current generating circuit includes a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, an eighth transistor, a ninth transistor, a first capacitor, a first resistor, and a second resistor; The gates of the first transistor, the second transistor, and the third transistor are connected together and connected to the initial voltage. The source of the first transistor is connected to reference ground via a first resistor. The sources of the second and third transistors are also connected to reference ground. The drain of the first transistor is connected to the drain of the fourth transistor. The source of the fourth transistor is connected to the drain of the seventh transistor. The gate of the fourth transistor is connected to the gate of the fifth transistor, the gate of the sixth transistor, and the drain of the sixth transistor. The gate of the seventh transistor is connected to the gate of the eighth transistor. The sources of the seventh and eighth transistors are connected to the power supply voltage. The drain of the second transistor is connected to the drain of the fifth transistor, the gate of the ninth transistor, and the first terminal of the first capacitor, generating a PTAT current. The source of the fifth transistor is connected to the drain of the eighth transistor. The drain of the ninth transistor is used to generate a CTAT current. The source of the ninth transistor is connected to the first terminal of the second resistor. The second terminal of the second resistor, the second terminal of the first capacitor, and the source of the third transistor are connected to reference ground. The drain of the third transistor is connected to the drain of the sixth transistor. The source of the sixth transistor is connected to the power supply voltage.

8. The temperature compensation module according to claim 7, characterized in that, The subtraction circuit includes the tenth transistor, the eleventh transistor, and the third resistor; The source of the tenth transistor is connected to the power supply voltage, the gate of the tenth transistor is connected to the gate of the eighth transistor, the drain of the tenth transistor is connected to the source of the eleventh transistor and the drain of the ninth transistor, the gate of the eleventh transistor is connected to the gate of the fifth transistor, the drain of the eleventh transistor is connected to the first terminal of the third resistor and generates a detection voltage, and the second terminal of the third resistor is connected to the reference ground.

9. The temperature compensation module according to claim 8, characterized in that, The startup circuit includes a twelfth transistor, a thirteenth transistor, a fourteenth transistor, and a second capacitor; The gate of the twelfth transistor is connected to the source of the twelfth transistor, the second terminal of the second capacitor, and the reference ground. The drain of the twelfth transistor is connected to the drain of the thirteenth transistor and the gate of the first transistor, and generates an initial voltage. The gate of the thirteenth transistor is connected to the drain of the fourteenth transistor and the first terminal of the second capacitor. The source of the thirteenth transistor is connected to the source of the fourteenth transistor and the power supply voltage. The gate of the fourteenth transistor is connected to the gate of the seventh transistor.

10. A temperature compensation method for an eddy current sensor, wherein the temperature compensation method utilizes the temperature compensation module of any one of claims 1-9 for temperature compensation, the temperature compensation method comprising: The temperature detection unit controls the temperature of the eddy current sensor based on the detection frequency and generates a real-time temperature detection value. The temperature difference judgment unit generates a temperature difference indication signal based on the change in the real-time temperature detection value; The temperature compensation control unit generates a real-time compensation value based on the temperature difference indication signal and the real-time temperature detection value, which is used to compensate for the angle measurement value of the eddy current sensor.

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