Temperature sampling circuit and temperature detection system of motor controller

Abstract

The invention provides a temperature sampling circuit and a temperature detection system of a motor controller, and the temperature sampling circuit comprises a sampling circuit which comprises a thermosensitive element and a first resistor, the first resistor and the thermosensitive element are connected in series to obtain a first branch, one end of the first branch is connected with a reference power port, and the other end of the first branch is grounded; the level conversion circuit comprises a second resistor, a third resistor and a level conversion sub-circuit, the second resistor and the third resistor are connected in series to obtain a second branch, one end of the second branch is connected with the reference power supply port, the other end of the second branch is grounded, and a first input end of the level conversion sub-circuit is connected with a node where the first resistor is connected with the thermosensitive element; the second input end is connected with a node where the second resistor and the third resistor are connected, and the output end of the level conversion sub-circuit is connected with the output filter circuit; one end of the output filter circuit is connected with the output end of the level conversion sub-circuit, and the other end of the output filter circuit is connected with a temperature detector. By adopting the scheme, the precision of temperature measurement can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of temperature measurement, and in particular to a temperature sampling circuit and a temperature detection system of a motor controller. Background Art

[0002] Temperature measurement and control protection are means to ensure the normal operation of electronic devices. For devices that require temperature protection, a temperature detection circuit is generally used to measure the temperature during operation so that over-temperature protection can be performed when the temperature is too high, ensuring that the temperature of the device does not exceed the maximum limit defined in its manual during normal operation. For example, for the motor controller of a new energy vehicle, it is necessary to detect the temperature of its internal power semiconductor.

[0003] At present, the temperature detection circuit commonly used in motor controllers uses NTC (Negative Temperature Coefficient) thermistors to sense temperature changes, and monitors the temperature corresponding to the current resistance value of the NTC thermistor by sampling the current / voltage of the NTC thermistor. However, the accuracy of temperature measurement of this circuit is low. Summary of the invention

[0004] The present application provides a temperature sampling circuit and a temperature detection system of a motor controller to solve the above-mentioned technical problems in the prior art.

[0005] According to a first aspect of the present application, a temperature sampling circuit is provided, comprising:

[0006] The sampling circuit includes a thermistor and a first resistor, wherein the first resistor and the thermistor are connected in series to obtain a first branch, wherein one end of the first branch is connected to a reference power supply port and the other end is grounded;

[0007] A level conversion circuit, comprising a second resistor, a third resistor and a level conversion subcircuit, wherein the second resistor and the third resistor are connected in series to obtain a second branch, the second branch is connected in parallel with the first branch, one end of the second branch is connected to the reference power supply port, and the other end is grounded, a first input end of the level conversion subcircuit is connected to a node where the first resistor and the thermistor are connected, a second input end of the level conversion subcircuit is connected to a node where the second resistor and the third resistor are connected, an output end of the level conversion subcircuit is connected to an output filter circuit, and the level conversion subcircuit performs level conversion based on a voltage signal input from the first input end and the second input end and outputs the voltage signal;

[0008] The output filter circuit has one end connected to the output end of the level conversion sub-circuit, and the other end connected to the temperature detector. The output filter circuit filters the input voltage signal and outputs it to the temperature detector.

[0009] In some embodiments, the thermal element is a positive temperature coefficient (PTC) thermistor.

[0010] In some implementations, the sampling circuit further includes a first filter capacitor, the first resistor in the first branch is connected to the reference power port, the thermistor is grounded, and the first filter capacitor is connected in parallel across the thermistor.

[0011] In some implementations, the level conversion circuit further includes a second filter capacitor, the second resistor in the second branch is connected to the reference power port, the third resistor is grounded, and the second filter capacitor is connected in parallel across the third resistor.

[0012] In some implementations, the level conversion subcircuit includes an operational amplifier and a fourth resistor;

[0013] The non-inverting input terminal of the operational amplifier serves as the first input terminal of the level conversion sub-circuit, and is connected to the node where the first resistor and the thermistor are connected. The inverting input terminal of the operational amplifier serves as the second input terminal of the level conversion sub-circuit, and is connected to the node where the second resistor and the third resistor are connected. One end of the fourth resistor is connected to the inverting input terminal of the operational amplifier, and the other end of the fourth resistor is connected to the output terminal of the operational amplifier. The output terminal of the operational amplifier serves as the output terminal of the level conversion sub-circuit, and is connected to the output filtering circuit.

[0014] In some implementations, the level conversion sub-circuit further includes a decoupling capacitor, one end of the decoupling capacitor is connected to the positive power supply terminal of the operational amplifier, and the other end of the decoupling capacitor is grounded.

[0015] In some implementations, the voltage signal output by the level conversion subcircuit through level conversion control is within a voltage input range of an input port of the temperature detector.

[0016] In some embodiments, the output filter circuit includes a filter resistor and a filter capacitor, one end of the filter resistor is connected to the output end of the level conversion subcircuit, and the other end of the filter resistor is connected to the temperature detector and grounded through the filter capacitor.

[0017] In some implementations, the temperature sampling circuit further includes a reference power supply, and the first branch and the second branch are connected to a reference power supply port of the reference power supply.

[0018] According to a second aspect of the present application, a temperature detection system of a motor controller is provided, comprising: a control chip of the motor controller and the above-mentioned temperature sampling circuit, wherein the temperature sampling circuit is arranged within a preset distance range of a device to be temperature-measured in the motor controller, and the control chip is connected to an output end of the output filter circuit as a temperature detector;

[0019] The control chip receives the voltage signal output by the temperature sampling circuit, obtains the resistance value of the thermistor based on the voltage signal, and determines the temperature detection value of the device to be measured based on the resistance value.

[0020] In summary, the temperature sampling circuit and the temperature detection system of the motor controller provided by the present application have at least the following features:

[0021] Beneficial effects:

[0022] On the one hand, the first resistor and the thermistor in the sampling circuit and the second resistor and the third resistor in the level conversion circuit form a Wheatstone bridge, and the temperature signal is converted into a voltage signal through the structure of the bridge resistor network, thereby improving the accuracy of temperature sampling; on the other hand, the second resistor and the third resistor form a level conversion circuit with the level conversion sub-circuit, thereby realizing the resistor multiplexing of the bridge resistor network, and the level conversion circuit performs level conversion processing on the voltage signal, and finally outputs the filtered voltage signal to the temperature detector through the output filter circuit, thereby improving the stability of temperature sampling, thereby improving the accuracy and stability of temperature measurement as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below in conjunction with the accompanying drawings. It is obvious that the drawings described below are some implementation methods of the present application. For those skilled in the art, other drawings or solutions can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a circuit diagram of a temperature detection circuit in the prior art;

[0025] Figure 2 A circuit structure diagram of a temperature sampling circuit provided for one embodiment of the present application;

[0026] Figure 3 A circuit schematic diagram of a temperature sampling circuit provided for another embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the above and other features and advantages of the present application more clear, the present application is further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are only exemplary and not restrictive.

[0028] In the following description, many specific details are set forth to provide a thorough understanding of the present application. However, it is apparent to those skilled in the art that specific details need not be adopted to practice the present application. In other cases, well-known steps or operations are not described in detail to avoid blurring the present application.

[0029] like Figure 1 As shown, most motor controllers currently use a resistor divider circuit for temperature sampling, and the resistor divider circuit includes a resistor R1, an NTC (negative temperature coefficient) thermistor and a resistor R2, and the NTC thermistor is connected in parallel with the resistor R2 and then in series with the resistor R1. As described in the background technology, the temperature measured by this circuit structure has low accuracy, and the NTC thermistor is applied to the temperature sampling of the motor controller, and its NTC semiconductor device cannot be standardized and has poor substitutability, and the measurement accuracy and linearity of the NTC are relatively poor as the temperature changes. Based on this, the present application provides a temperature sampling circuit that can improve the accuracy of temperature measurement.

[0030] This application provides a temperature sampling circuit, referring to Figure 2 The temperature sampling circuit includes a sampling circuit 110 , a level conversion circuit 120 and an output filtering circuit 130 .

[0031] The sampling circuit 110 includes a thermistor 111 and a first resistor R1. The first resistor R1 and the thermistor 111 are connected in series to obtain a first branch. One end of the first branch is connected to a reference power port VREF, and the other end is grounded. Specifically, the reference power port VREF is used to provide a reference voltage to supply power to the first branch. The thermistor 111 changes its resistance as the temperature changes, so that the voltage between the nodes TEMP-P and TEMP-N at both ends of the thermistor 111 changes as the temperature changes. It can be understood that in addition to the first resistor R1 and the thermistor 111, other devices can be connected in series on the first branch according to actual needs, for example, multiple resistors can be connected in series according to resistance requirements.

[0032] The level conversion circuit 120 includes a second resistor R2, a third resistor R3 and a level conversion sub-circuit 121. The second resistor R2 and the third resistor R3 are connected in series to obtain a second branch. The second branch is connected in parallel with the first branch, and one end of the second branch is connected to the reference power port VREF, and the other end is grounded. The reference voltage provided by the reference power port VREF supplies power to the second branch. Specifically, the first branch and the second branch are connected in parallel, so that the first resistor R1, the thermistor 111, the second resistor R2 and the third resistor R3 form a bridge resistor network of a Wheatstone bridge, such as Figure 2 As shown in the dotted box, the bridge resistor network converts the sampled temperature signal into a voltage signal. When the temperature sensed by the thermistor 111 changes, the voltage at the connection node between the first resistor R1 and the thermistor 111 changes accordingly.

[0033] The first input end of the level conversion subcircuit 121 is connected to the node where the first resistor R1 and the thermistor 111 are connected, the second input end of the level conversion subcircuit 121 is connected to the node where the second resistor R2 and the third resistor R3 are connected, and the output end of the level conversion subcircuit 121 is connected to the output filter circuit 130. The level conversion subcircuit 121 performs level conversion based on the voltage signal input from the first input end and the second input end and outputs it, and specifically, the voltage signal may be amplified and output to the output filter circuit 130.

[0034] Among them, one end of the output filter circuit 130 is connected to the output end of the level conversion sub-circuit 121, and the other end of the output filter circuit 130 is connected to the temperature detector. For example, the output filter circuit 130 is connected to the temperature detector through the port TEMP-OUT. Specifically, the output filter circuit 130 filters the input voltage signal and outputs it to the temperature detector, filters the noise, improves the stability of the voltage output, and thus improves the stability of the temperature sampling circuit. Specifically, the temperature detector can determine the resistance value of the thermistor 111 according to the input voltage signal, and then obtain the current temperature detection value according to the corresponding relationship table between the resistance value of the thermistor 111 and the temperature.

[0035] For example, the temperature sampling circuit can be used in the motor controller of an electric vehicle; the temperature sampling circuit is set within a preset distance range of the device to be measured, close to the device to be measured, specifically, the thermistor 111 in the sampling circuit 110 is close to the device to be measured; the control chip of the motor controller is used as a temperature detector, the control chip receives the voltage signal output by the output filter circuit 130, and obtains the resistance value of the thermistor 111 based on the voltage signal, and determines the temperature detection value of the device to be measured based on the corresponding relationship table between the resistance value and the temperature. In this way, the temperature sampling circuit can be used to more accurately feedback the temperature of the device to be measured in the motor controller, and protective measures can be taken when the temperature detection value is too high to ensure that the temperature of the device to be measured does not exceed the maximum limit during normal operation.

[0036] In the above-mentioned temperature sampling circuit, on the one hand, the first resistor R1 and the thermistor 111 in the sampling circuit 110 and the second resistor R2 and the third resistor R3 in the level conversion circuit 120 form a Wheatstone bridge, and the temperature signal is converted into a voltage signal through the structure of the bridge resistor network, thereby improving the accuracy of temperature sampling; on the other hand, the second resistor R2 and the third resistor R3 and the level conversion sub-circuit 121 form a level conversion circuit 120, thereby realizing the resistor multiplexing of the bridge resistor network, and the level conversion circuit 120 performs level conversion processing on the voltage signal, and finally outputs the filtered voltage signal to the temperature detector through the output filter circuit 130, thereby improving the stability of temperature sampling, thereby improving the accuracy and stability of temperature measurement as a whole.

[0037] In some embodiments, the thermistor is a positive temperature coefficient (PTC) thermistor. The resistance of a positive temperature coefficient (PTC) thermistor increases with increasing temperature. Compared with an NTC thermistor, a positive temperature coefficient (PTC) thermistor has higher substitutability, higher reliability, and higher precision and linearity, thereby improving the precision and linearity of temperature sampling.

[0038] In some embodiments, reference Figure 3 The sampling circuit 110 also includes a first filter capacitor C1. The first end of the first resistor R1 in the first branch is connected to the reference power port VREF. The second end of the first resistor R1 is connected to the first end of the thermistor 111. The second end of the thermistor 111 is grounded. The first filter capacitor C1 is connected in parallel to both ends of the thermistor 111.

[0039] Taking a positive temperature coefficient PTC thermistor as an example, the first filter capacitor C1 is connected in parallel at both ends of the positive temperature coefficient PTC thermistor. By connecting the first filter capacitor C1 in parallel at both ends of the thermistor 111, differential mode filtering is performed to enhance the signal, thereby improving the reliability of temperature sampling.

[0040] In some embodiments, reference Figure 3 The level conversion circuit 120 also includes a second filter capacitor C2, a first end of a second resistor R2 in the second branch is connected to a reference power port VREF, a second end of the second resistor R2 is connected to a first end of a third resistor R3, a second end of the third resistor R3 is grounded, and the second filter capacitor C2 is connected in parallel to both ends of the third resistor R3. By connecting the second filter capacitor in parallel to both ends of the third resistor R3, common mode filtering is performed to filter out interference signals, thereby improving the accuracy of temperature sampling.

[0041] In some embodiments, reference Figure 3The level conversion sub-circuit 121 includes an operational amplifier U1 and a fourth resistor R4. The non-inverting input terminal of the operational amplifier U1 is used as the first input terminal of the level conversion sub-circuit 121, connected to the node where the first resistor R1 and the thermistor 111 are connected. The reverse input terminal of the operational amplifier U1 is used as the second input terminal of the level conversion sub-circuit 121, connected to the node where the second resistor R2 and the third resistor R3 are connected. One end of the fourth resistor R4 is connected to the reverse input terminal of the operational amplifier U1, and the other end of the fourth resistor R4 is connected to the output terminal of the operational amplifier U1. The output terminal of the operational amplifier U1 is used as the output terminal of the level conversion sub-circuit 121, connected to the output filter circuit 130.

[0042] The second resistor R2, the third resistor R3, the fourth resistor R4, and the operational amplifier U1 form a reverse proportional amplification circuit. The second resistor R2 and the third resistor R3 are used to form a bridge resistor network, and are matched with the operational amplifier U1 and the fourth resistor R4 to form a level conversion circuit 120, so as to realize the resistor reuse of the bridge resistor network, simplify the circuit structure, and amplify the voltage signal by the operational amplifier U1, so as to improve the accuracy and high reliability of the sampling circuit. Specifically, through the parameter design of the circuit components, the voltage at the reverse input terminal of the operational amplifier U1 can be amplified to 0.477V-4.498V.

[0043] In some embodiments, reference Figure 3 The level conversion sub-circuit 121 also includes a decoupling capacitor C3, one end of which is connected to the positive power supply terminal of the operational amplifier U1, and the other end of the decoupling capacitor C3 is grounded. Specifically, the positive power supply terminal of the operational amplifier U1 is also connected to the reference power supply port VREF, and the reference voltage provided by the reference power supply port VREF is used to power the operational amplifier U1; the negative power supply terminal of the operational amplifier U1 is grounded. By connecting the grounded decoupling capacitor C3 to the positive power supply terminal of the operational amplifier U1, the noise of the positive power supply terminal is reduced, the power supply stability is improved, and thus the working stability of the operational amplifier U1 is improved.

[0044] In some embodiments, the magnitude of the voltage signal output by the level conversion subcircuit 121 through level conversion control is within the voltage input range of the input port of the temperature detector. Specifically, the magnitude of the voltage signal obtained after the voltage signal output by the level conversion subcircuit 121 is filtered by the output filter circuit 130 is within the voltage input range of the input port of the temperature detector.

[0045] The input port of the temperature detector refers to a port connected to the output filter circuit 130 to input a voltage signal. Taking the control chip of the motor controller as an example, the input port of the control chip connected to the output filter circuit 130 is an AD (analog-to-digital) conversion port. The voltage input range of the input port refers to the voltage range allowed to be input by the input port. Taking the AD conversion port of the control chip as an example, the voltage range allowed to be input by the AD conversion port is 0V-5V, and the voltage input range is 0V-5V.

[0046] Through the level conversion of the level conversion sub-circuit 121, the magnitude of the voltage signal output by the level conversion sub-circuit 121 is within the voltage input range of the input port of the temperature detector, so that the voltage signal output to the temperature detector directly meets the voltage magnitude requirement of the input port, and there is no need to add an overvoltage protection circuit, which can save circuit costs.

[0047] Specifically, the voltage output range of the operational amplifier U1 is 0.477V-4.498V, that is, the voltage output by the port TEMP-OUT is 0.477V-4.498V, which meets the design requirement of 0V-5V of the AD conversion port of the control chip of the motor controller.

[0048] In some embodiments, reference Figure 3 The output filter circuit 130 includes a filter resistor R5 and a filter capacitor C4. One end of the filter resistor R5 is connected to the output end of the level conversion sub-circuit 121, and the other end of the filter resistor R5 is connected to the temperature detector and grounded through the filter capacitor C4.

[0049] By using the filter resistor R5 and the filter capacitor C4 to form a low-pass filter, the voltage signal output by the level conversion sub-circuit 121 is filtered to ensure that the output is not affected by line or high-frequency noise, thereby improving the accuracy of temperature measurement.

[0050] In some embodiments, the temperature sampling circuit further includes a reference power supply, and the first branch and the second branch are connected to a reference power supply port VREF of the reference power supply. Specifically, the first resistor R1 and the second resistor R2 are connected to the reference power supply port VREF of the reference power supply. Furthermore, the positive power supply terminal of the operational amplifier U1 is connected to the reference power supply port VREF of the reference power supply. By adopting the reference power supply for single power supply, there is no need to generate an additional excitation voltage, and the circuit structure is simpler.

[0051] In addition, the present application provides a temperature detection system for a motor controller, including a control chip of the motor controller and a temperature sampling circuit in each of the above embodiments, wherein the temperature sampling circuit is arranged within a preset distance range of a temperature-tested device in the motor controller, wherein the preset distance range can be set to a distance range close to the temperature-tested device according to actual needs. The control chip is connected to the output end of the output filter circuit 130 as a temperature detector.

[0052] The control chip receives the voltage signal output by the temperature sampling circuit, obtains the resistance value of the thermistor based on the voltage signal, and determines the temperature detection value of the device to be measured based on the resistance value. Specifically, the control chip calculates the current resistance value of the thermistor according to the value of the voltage signal and the calculation relationship between the value of the voltage signal and the resistance value, and then determines the temperature detection value corresponding to the current resistance value according to the corresponding relationship table between the resistance value and the temperature of the thermistor as the current temperature of the device to be measured, thereby realizing the temperature measurement.

[0053] The temperature detection system adopts the temperature sampling circuit in the above-mentioned embodiments. Similarly, the temperature sampling has high accuracy and reliability, so the temperature measurement of the device to be measured has high accuracy and reliability.

[0054] Taking the temperature measurement of the SIC (silicon carbide) power semiconductor of the motor controller as an example, the temperature sampling circuit is set near the SIC power semiconductor to monitor the working temperature of the SIC power semiconductor. Among them, the operational amplifier U1 selects the TI-LM2904 operational amplifier, and the positive temperature coefficient PTC thermistor selects PT1000. The bridge resistor network is composed of the first resistor R1, the positive temperature coefficient PTC thermistor, the second resistor R2, and the third resistor R3. As the temperature of the SIC power semiconductor changes, the resistance of the positive temperature coefficient PTC thermistor also changes accordingly, and the voltage at both ends also changes with the temperature. The positive temperature coefficient PTC thermistor is between -50℃ and 200℃, and its corresponding change is 803.06Ω-1791.61Ω, and the voltage at both ends changes to 0.884V~1.488V. The connection node of the first resistor R1 and the positive temperature coefficient PTC thermistor serves as the same-direction input terminal signal of the operational amplifier U1, and the divided voltage of the second resistor R2 and the third resistor R3 is equivalent to the reverse input terminal signal of the operational amplifier U1. At the same time, the second resistor R2, the third resistor R3, the fourth resistor R4 and the operational amplifier U1 form a same-direction amplification circuit and a reverse proportional amplification circuit, and the same-direction amplification factor is 6.568, and the reverse amplification factor is 5.568. When the two are superimposed, the output range of the operational amplifier U1 is 0.477V-4.498V, that is, the port TEMP-OUT output has an output range of 0.477V-4.498V, which meets the design requirement of 0~5V of the AD conversion port of the control chip of the motor controller, and there is no need to add an overvoltage protection circuit, which can save the cost of this part of the circuit.

[0055] The temperature sampling circuit structure of this embodiment has the advantage that the PTC small voltage signal can be amplified to the full voltage range detectable by the control chip, the sampling resolution can be reduced, and the impact of AD acquisition error can be further improved; and in the full temperature range (-50℃-200℃), the linearity is higher, and the accuracy can reach ±1.5%. The output filter circuit 130 adopts a filter resistor R5 and a filter capacitor C4 to form a low-pass filter circuit, and its cut-off frequency fc=1 / 2*pi*R*C, where R is equal to the resistance of the filter resistor R5, and C is equal to the capacitance of the filter capacitor C4. In this embodiment, fc is set to 100Hz, and its cut-off frequency can be adjusted later according to actual needs. The output voltage of the operational amplifier U1 passes through this output filter circuit 130, and all noises exceeding fc are filtered out, and then output to the AD conversion port of the control chip.

[0056] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A temperature sampling circuit, characterized in that: include: The sampling circuit includes a thermistor and a first resistor, wherein the first resistor and the thermistor are connected in series to obtain a first branch, wherein one end of the first branch is connected to a reference power supply port and the other end is grounded; A level conversion circuit, comprising a second resistor, a third resistor and a level conversion subcircuit, wherein the second resistor and the third resistor are connected in series to obtain a second branch, the second branch is connected in parallel with the first branch, one end of the second branch is connected to the reference power supply port, and the other end is grounded, a first input end of the level conversion subcircuit is connected to a node where the first resistor and the thermistor are connected, a second input end of the level conversion subcircuit is connected to a node where the second resistor and the third resistor are connected, an output end of the level conversion subcircuit is connected to an output filter circuit, and the level conversion subcircuit performs level conversion based on a voltage signal input from the first input end and the second input end and outputs the voltage signal; The output filter circuit has one end connected to the output end of the level conversion sub-circuit, and the other end connected to the temperature detector. The output filter circuit filters the input voltage signal and outputs it to the temperature detector.

2. The temperature sampling circuit according to claim 1, characterized in that: The thermal element is a positive temperature coefficient PTC thermistor.

3. The temperature sampling circuit according to claim 1, characterized in that: The sampling circuit further includes a first filter capacitor, the first resistor in the first branch is connected to the reference power port, the thermistor is grounded, and the first filter capacitor is connected in parallel at both ends of the thermistor.

4. The temperature sampling circuit according to claim 1, characterized in that: The level conversion circuit further includes a second filter capacitor. The second resistor in the second branch is connected to the reference power port, the third resistor is grounded, and the second filter capacitor is connected in parallel at both ends of the third resistor.

5. The temperature sampling circuit according to any one of claims 1 to 4, characterized in that: The level conversion sub-circuit includes an operational amplifier and a fourth resistor; The non-inverting input terminal of the operational amplifier serves as the first input terminal of the level conversion sub-circuit, and is connected to the node where the first resistor and the thermistor are connected. The inverting input terminal of the operational amplifier serves as the second input terminal of the level conversion sub-circuit, and is connected to the node where the second resistor and the third resistor are connected. One end of the fourth resistor is connected to the inverting input terminal of the operational amplifier, and the other end of the fourth resistor is connected to the output terminal of the operational amplifier. The output terminal of the operational amplifier serves as the output terminal of the level conversion sub-circuit, and is connected to the output filtering circuit.

6. The temperature sampling circuit according to claim 5, characterized in that: The level conversion sub-circuit further includes a decoupling capacitor, one end of which is connected to the positive power supply terminal of the operational amplifier, and the other end of which is grounded.

7. The temperature sampling circuit according to claim 1, characterized in that: The voltage signal output by the level conversion subcircuit is controlled to be within the voltage input range of the input port of the temperature detector through level conversion.

8. The temperature sampling circuit according to claim 1, characterized in that: The output filter circuit comprises a filter resistor and a filter capacitor. One end of the filter resistor is connected to the output end of the level conversion subcircuit, and the other end of the filter resistor is connected to the temperature detector and is grounded through the filter capacitor.

9. The temperature sampling circuit according to claim 1, characterized in that: It also includes a reference power supply, and the first branch and the second branch are connected to a reference power supply port of the reference power supply.

10. A temperature detection system for a motor controller, characterized in that: A control chip of a motor controller and a temperature sampling circuit as claimed in any one of claims 1 to 9, wherein the temperature sampling circuit is arranged within a preset distance range of a temperature-measured device in the motor controller, and the control chip is connected to an output end of the output filter circuit as a temperature detector; The control chip receives the voltage signal output by the temperature sampling circuit, obtains the resistance value of the thermistor based on the voltage signal, and determines the temperature detection value of the device to be measured based on the resistance value.

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