IGBT-based temperature sampling circuit and temperature detection system

Abstract

The invention provides an IGBT-based temperature sampling circuit and a temperature detection system, the circuit comprises a sampling circuit, a level conversion circuit and an output filter circuit, the sampling circuit comprises an IGBT integrated with a thermosensitive element, a first resistor and a constant current source excitation sub-circuit, the thermosensitive element and the first resistor are connected in series to obtain a first branch and are connected with the reference power supply port and the output end of the constant current source excitation sub-circuit, and the junction of the first resistor and the thermosensitive element is connected with the input end of the constant current source excitation sub-circuit; 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 and are connected with the reference power supply port and the output end of the constant current source excitation sub-circuit, and the input end of the level conversion sub-circuit is connected with a node where the second resistor and the third resistor are connected; the output end of the level conversion sub-circuit is connected with the output filter circuit; the output filter circuit is connected with the temperature detector. By adopting the scheme, the precision of temperature measurement can be improved.

Description

Technical Field

[0001] The present application relates to the field of temperature measurement technology, and in particular to an IGBT-based temperature sampling circuit and a temperature detection system. Background Art

[0002] In new energy electric vehicles, motor controllers mostly use IGBTs (Insulated Gate Bipolar Transistor) for power output control. In order to ensure normal operation, it is necessary to measure the IGBT junction temperature so that over-temperature protection can be performed when the temperature is too high to ensure that the temperature of the IGBT does not exceed the maximum limit during normal operation.

[0003] At present, most semiconductor manufacturers use IGBTs with integrated thermal sensors. The temperature sampling design is based on the thermal sensors integrated inside the IGBT to sense temperature changes, and the temperature corresponding to the current resistance of the thermal sensors is monitored by sampling the current / voltage of the thermal sensors. However, the accuracy of temperature measurement of this circuit is low. Summary of the invention

[0004] The present application provides an IGBT-based temperature sampling circuit and a temperature detection system 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 based on an IGBT is provided, comprising:

[0006] A sampling circuit, comprising an IGBT with an integrated thermistor, a first resistor and a constant current source excitation subcircuit, wherein the constant current source excitation subcircuit comprises an input end and an output end, the thermistor integrated in the IGBT is connected in series with the first resistor to obtain a first branch, one end of the first resistor in the first branch is connected to a reference power supply port, one end of the thermistor is connected to the output end of the constant current source excitation subcircuit, and a node connecting the first resistor and the thermistor is connected to the input end of the constant current source excitation subcircuit;

[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, and one end of the second branch is connected to the reference power port, and the other end is connected to the output end of the constant current source excitation subcircuit, the input end of the level conversion subcircuit is connected to the node where the second resistor and the third resistor are connected, the output end of the level conversion subcircuit is connected to the output filter circuit, and the level conversion subcircuit performs level conversion on the voltage signal input from the input end and outputs the voltage signal;

[0008] An output filter circuit, one end of which is connected to the output end of the level conversion sub-circuit, and the other end of which is connected to a 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 embodiments, the constant current source excitation subcircuit includes a first operational amplifier, the inverting input terminal of the first operational amplifier serves as the input terminal of the constant current source excitation subcircuit, connected to the node where the first resistor and the thermistor are connected, the same-direction input terminal of the first operational amplifier is grounded, and the output terminal of the first operational amplifier serves as the output terminal of the constant current source excitation subcircuit, connected to one end of the thermistor in the first branch and one end of the third resistor in the second branch.

[0011] In some implementations, the constant current source excitation subcircuit further includes a first decoupling capacitor, one end of the first decoupling capacitor is connected to the positive power supply terminal of the first operational amplifier, and the other end of the first decoupling capacitor is grounded.

[0012] 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.

[0013] In some embodiments, the level conversion sub-circuit includes a second operational amplifier, a fourth resistor and a fifth resistor, the same-direction input terminal of the second operational amplifier serves as the input terminal of the level conversion sub-circuit and is connected to the node where the second resistor and the third resistor are connected, the reverse input terminal of the second operational amplifier is connected to one end of the fourth resistor and one end of the fifth resistor, the other end of the fourth resistor is grounded, the other end of the fifth resistor is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier serves as the output terminal of the level conversion sub-circuit and is connected to the output filter circuit.

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

[0015] 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.

[0016] In some implementations, the IGBT-based 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.

[0017] According to a second aspect of the present application, there is provided an IGBT-based temperature detection system, comprising a control chip of a motor controller and the above-mentioned IGBT-based temperature sampling circuit, wherein the thermistor integrated in the IGBT is located within a preset distance range of the IGBT, and the control chip is connected to the output end of the output filter circuit as a temperature detector;

[0018] The control chip receives the voltage signal output by the IGBT-based temperature sampling circuit, obtains the resistance value of the thermistor based on the voltage signal, and determines the temperature detection value of the IGBT based on the resistance value.

[0019] In summary, the IGBT-based temperature sampling circuit and temperature detection system provided by the present application have at least the following features:

[0020] Beneficial effects:

[0021] A Wheatstone bridge is formed by the first resistor and thermistor in the sampling circuit and the second resistor and the third resistor in the level conversion circuit. The temperature signal is converted into a voltage signal through a constant current source excitation subcircuit in cooperation with the structure of the bridge resistor network, thereby improving the accuracy of temperature sampling. At the same time, the second resistor and the third resistor form a level conversion circuit with the level conversion subcircuit to realize the resistor multiplexing of the bridge resistor network. After the level conversion circuit performs level conversion processing on the voltage signal, the output filter circuit finally outputs the filtered voltage signal to the temperature detector, thereby improving the stability of temperature sampling, thereby improving the accuracy and stability of IGBT temperature measurement as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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.

[0023] Figure 1 It is a circuit diagram for sampling IGBT temperature in the prior art;

[0024] Figure 2 A circuit structure diagram of a temperature sampling circuit based on IGBT provided in one embodiment of the present application;

[0025] Figure 3A circuit schematic diagram of a temperature sampling circuit based on IGBT provided in another embodiment of the present application;

[0026] Figure 4 FIG. 1 is a graph showing the relationship between the output voltage and temperature of an IGBT-based temperature sampling circuit in an embodiment. 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] In the prior art, most motor controllers use IGBTs that integrate NTC (Negative Temperature Coefficient) thermistors by welding. The circuit design for sampling the temperature of the IGBT is as follows: Figure 1 As shown, a resistor R2 is connected in parallel with an NTC thermistor integrated in the IGBT and then connected in series with a resistor R1 to form a resistor divider circuit for temperature sampling. As described in the background technology, the temperature measurement accuracy of this circuit structure is low. Based on this, the present application provides a solution that can improve the IGBT temperature measurement accuracy.

[0030] The present application provides a temperature sampling circuit based on IGBT, such as Figure 2 As shown, the IGBT-based temperature sampling circuit includes a sampling circuit 210 , a level conversion circuit 220 and an output filtering circuit 230 .

[0031] The sampling circuit 210 includes an IGBT with an integrated thermistor R2, a first resistor R1, and a constant current source excitation subcircuit 211. The constant current source excitation subcircuit 211 includes an input terminal TEM-P and an output terminal TEM-N. The thermistor R2 integrated in the IGBT is connected in series with the first resistor R1 to obtain a first branch. In the first branch, the first end of the first resistor R1 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 R2, the second end of the thermistor R2 is connected to the output terminal TEM-N of the constant current source excitation subcircuit 211, and the node where the first resistor R1 and the thermistor R2 are connected is connected to the input terminal TEM-P of the constant current source excitation subcircuit 211. It can be understood that in addition to the first resistor R1 and the thermistor R2, 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 220 includes a second resistor R3, a third resistor R4 and a level conversion sub-circuit 221. The second resistor R3 and the third resistor R4 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 connected to the output end TEM-N of the constant current source excitation sub-circuit 211. Specifically, the reference voltage provided by the reference power port VREF supplies power to the second branch, and one end of the second resistor R3 can be connected to the reference power port VREF, and one end of the third resistor R4 can be connected to the output end of the constant current source excitation sub-circuit 211. The input end of the level conversion sub-circuit 221 is connected to the node where the second resistor R3 and the third resistor R4 are connected, and the output end of the level conversion sub-circuit 221 is connected to the output filter circuit 130. The level conversion sub-circuit 221 performs level conversion on the voltage signal inputted from the input end and outputs it, and specifically, the voltage signal can be amplified and outputted to the output filter circuit 130.

[0033] Specifically, the reference power supply port VREF is used to provide a reference voltage to supply power to the first branch and the second branch. The constant current source circuit composed of the first resistor R1 and the constant current source excitation subcircuit 211 provides a constant current source excitation signal to act on the thermistor R2. No matter how the temperature changes, the current passing through the first resistor R1 is constant. Specifically, the first branch and the second branch are connected in parallel, so that the first resistor R1, the thermistor R2 integrated in the IGBT, the second resistor R3 and the third resistor R4 constitute a bridge resistor network of the Wheatstone bridge. The constant current source excitation subcircuit 211 cooperates with the bridge resistor network to convert the sampled temperature signal into a voltage signal. When the temperature near the thermistor R2 changes, the thermistor R2 changes its resistance with the change of temperature, and the voltage of the output terminal TEM-N of the constant current source excitation subcircuit 211 changes accordingly. Advantageously, the first resistor R1 of one arm of the bridge resistor network is used together with the constant current source excitation subcircuit 211 to form a constant current source circuit; the second resistor R3, the third resistor R4 of the other arm of the bridge resistor network and the level conversion subcircuit 221 are used together to form a level conversion circuit 220, thereby realizing the reuse of the bridge resistor network.

[0034] Among them, one end of the output filter circuit 230 is connected to the output end of the level conversion sub-circuit 221, and the other end of the output filter circuit 230 is connected to the temperature detector. For example, the output filter circuit 230 is connected to the temperature detector through the port TEMP-OUT. Specifically, the output filter circuit 230 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 R2 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 R2 and the temperature.

[0035] For example, the above-mentioned IGBT-based temperature sampling circuit can be used to measure the temperature of the IGBT of the electric vehicle motor controller; the thermistor R2 in the IGBT-based temperature sampling circuit is located near the IGBT; 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 230, and obtains the resistance value of the thermistor R2 based on the voltage signal, and determines the temperature detection value of the IGBT based on the corresponding relationship table between the resistance value and the temperature as the junction temperature of the IGBT. In this way, the junction temperature of the IGBT of the motor controller can be fed back more accurately by using the IGBT-based temperature sampling circuit, and protective measures can be taken when the junction temperature is too high to ensure that the temperature of the IGBT does not exceed the maximum limit during normal operation.

[0036] The above-mentioned IGBT-based temperature sampling circuit forms a Wheatstone bridge through the first resistor R1 and thermistor R2 in the sampling circuit 210 and the second resistor R3 and the third resistor R4 in the level conversion circuit 220. The temperature signal is converted into a voltage signal through the constant current source excitation subcircuit 211 in conjunction with the structure of the bridge resistor network, thereby improving the accuracy of temperature sampling; at the same time, the second resistor R3 and the third resistor R4 and the level conversion subcircuit 221 form a level conversion circuit 220 to realize the resistor multiplexing of the bridge resistor network. After the level conversion circuit 220 performs level conversion processing on the voltage signal, the filtered voltage signal is finally output to the temperature detector by the output filter circuit 130, thereby improving the stability of temperature sampling, thereby improving the accuracy and stability of IGBT temperature measurement as a whole.

[0037] In some embodiments, the thermosensitive element R2 is a positive temperature coefficient PTC thermistor. Specifically, the IGBT is an IGBT with an internally integrated positive temperature coefficient PTC thermistor, and further, is an IGBT with an internally integrated positive temperature coefficient PTC thermistor through silver sintering technology.

[0038] In the conventional technology, an IGBT is integrated with an NTC thermistor. As the temperature changes, the resistance of the NTC thermistor changes greatly, resulting in poor linearity and accuracy of temperature measurement based on NTC. In addition, the NTC thermistor can only be packaged inside the IGBT by welding, which is far away from the IGBT chip. Moreover, the welding process will increase the thermal resistance between the NTC and the junction, and the IGBT cannot give full play to its performance. This embodiment uses an IGBT with an integrated positive temperature coefficient PTC thermistor. Compared with the traditional IGBT with an integrated NTC thermistor, on the one hand, the resistance of the positive temperature coefficient PTC thermistor increases with the increase of temperature, and its linearity and measurement accuracy are better, thereby improving the linearity and accuracy of temperature sampling, so that the junction temperature of the motor controller IGBT can be fed back more accurately. On the other hand, the positive temperature coefficient PTC thermistor can be packaged in the IGBT using silver sintering technology, has low thermal resistance and can be packaged close to the IGBT chip, which can improve the sensitivity of temperature sensing, thereby improving the accuracy of temperature sampling.

[0039] In some embodiments, reference Figure 3 The constant current source excitation subcircuit 211 includes a first operational amplifier U1, and the inverting input terminal of the first operational amplifier U1 is used as the input terminal of the constant current source excitation subcircuit 211, and is connected to the node where the first resistor R1 and the thermistor R2 are connected. The non-inverting input terminal of the first operational amplifier U1 is grounded, and the output terminal of the first operational amplifier U1 is used as the output terminal of the constant current source excitation subcircuit 211, and is connected to one end of the thermistor R2 in the first branch and one end of the third resistor R4 in the second branch.

[0040] Specifically, the first resistor R1 and the first operational amplifier U1 form a constant current source circuit to provide a constant current source excitation signal, which acts on the thermistor R2. Since the same-direction input terminal of the first operational amplifier U1 is grounded, according to the "virtual short" characteristic of the operational amplifier, it can be known that the reverse input terminal voltage is 0. As long as the first resistor R1 is determined, its constant current source value will remain unchanged. According to the "virtual open" characteristic of the operational amplifier, it can be known that the current passing through the thermistor R2 is the constant current source value, and the resistance value of the thermistor R2 changes with temperature, so the voltage of the output terminal TEM-N of the first operational amplifier U1 changes with temperature. In this way, the first operational amplifier U1 cooperates with the first resistor R1 to provide a constant current flowing through the thermistor R2, and cooperates with the bridge resistor network to convert the temperature signal into a voltage signal, thereby improving the accuracy of temperature sampling. Specifically, the resistance value of the first resistor R1 and the reference voltage provided by the reference power port VREF can be set to set the current of the first branch to a smaller current, so that the heat generated by the thermistor R2 is as small as possible, thereby reducing the influence of the heat generated by the thermistor R2 on temperature sensing and improving the accuracy of temperature measurement.

[0041] In some embodiments, reference Figure 3 The constant current source excitation subcircuit 211 also includes a first decoupling capacitor C1, one end of which is connected to the positive power supply terminal of the first operational amplifier U1, and the other end of the first decoupling capacitor C1 is grounded. Specifically, the positive power supply terminal of the first 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 first operational amplifier U1; the negative power supply terminal of the first operational amplifier U1 is grounded. By connecting the grounded first decoupling capacitor C1 to the positive power supply terminal of the first 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 first operational amplifier U1 is improved.

[0042] In some embodiments, the magnitude of the voltage signal output by the level conversion subcircuit 221 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 221 is filtered by the output filter circuit 230 is within the voltage input range of the input port of the temperature detector.

[0043] 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.

[0044] Through the level conversion of the level conversion sub-circuit 221, the magnitude of the voltage signal output by the level conversion sub-circuit 221 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.

[0045] In some embodiments, reference Figure 3 The level conversion sub-circuit 221 includes a second operational amplifier U2, a fourth resistor R5 and a fifth resistor R6. The non-inverting input terminal Vp of the second operational amplifier U2 serves as the input terminal of the level conversion sub-circuit 221 and is connected to the node where the second resistor R3 and the third resistor R4 are connected. The reverse input terminal Vn of the second operational amplifier U2 is connected to one end of the fourth resistor R5 and one end of the fifth resistor R6. The other end of the fourth resistor R5 is grounded. The other end of the fifth resistor R6 is connected to the output terminal of the second operational amplifier U2. The output terminal of the second operational amplifier U2 serves as the output terminal of the level conversion sub-circuit 221 and is connected to the output filter circuit 230.

[0046] In this embodiment, the second resistor R3, the third resistor R4, the second operational amplifier U2, the fourth resistor R5 and the fifth resistor R6 form a reverse amplification circuit, wherein the reference voltage provided by the reference power supply port VREF and the voltage of the output terminal TEMP-N of the constant current source excitation subcircuit 211 act on the voltage of the connection node between the second resistor R3 and the third resistor R4 as the voltage signal of the same-direction input terminal of the second operational amplifier U2. The reverse amplification circuit amplifies the voltage signal of the same-direction input terminal to improve the accuracy of temperature sampling.

[0047] Specifically, the second operational amplifier U1 amplifies the voltage signal at the same-direction input terminal to 0.5V-4.5V, so that the voltage output by the port TEMP-OUT is 0.5V-4.5V, which meets the design requirement of 0V-5V of the AD conversion port of the control chip of the motor controller. There is no need to add an overvoltage protection circuit to the AD conversion port, saving circuit costs.

[0048] In some embodiments, reference Figure 3 The level conversion sub-circuit 221 also includes a second decoupling capacitor C2, one end of which is connected to the positive power supply terminal of the second operational amplifier U2, and the other end of the second decoupling capacitor C2 is grounded. Specifically, the positive power supply terminal of the second operational amplifier U2 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 second operational amplifier U2; the negative power supply terminal of the second operational amplifier U2 is grounded. By connecting the grounded second decoupling capacitor C2 to the positive power supply terminal of the second operational amplifier U2, the noise of the positive power supply terminal is reduced, the power supply stability is improved, and thus the working stability of the second operational amplifier U2 is improved.

[0049] In some embodiments, reference Figure 3 The output filter circuit 230 includes a filter resistor R7 and a filter capacitor C3. One end of the filter resistor R7 is connected to the output end of the level conversion sub-circuit 221, and the other end of the filter resistor R7 is connected to the temperature detector and grounded through the filter capacitor C3.

[0050] By using the filter resistor R7 and the filter capacitor C3 to form a low-pass filter, the voltage signal output by the level conversion sub-circuit 221 is filtered to ensure that the output is not affected by line or high-frequency noise, thereby improving the accuracy of temperature measurement.

[0051] In some embodiments, the above-mentioned IGBT-based temperature sampling circuit also 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 R3 are connected to the reference power supply port VREF of the reference power supply. Further, the positive power supply terminal of the first operational amplifier U1 and the positive power supply terminal of the second operational amplifier U2 are 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.

[0052] The present application provides an IGBT-based temperature detection system, including a control chip of a motor controller and an IGBT-based temperature sampling circuit in any of the above embodiments, wherein the thermistor R2 integrated in the IGBT is located within a preset distance range of the IGBT, so that the thermistor R2 is close to the IGBT chip. The control chip is used as a temperature detector and is connected to the output end of the output filter circuit 230.

[0053] The control chip receives the voltage signal output by the temperature sampling circuit based on the IGBT, obtains the resistance value of the thermistor R2 based on the voltage signal, and determines the temperature detection value of the IGBT based on the resistance value. Specifically, the control chip calculates the current resistance value of the thermistor R2 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 of the thermistor R2 and the temperature, as the junction temperature of the IGBT, thereby realizing the temperature measurement.

[0054] The above-mentioned IGBT-based temperature detection system adopts the IGBT-based temperature sampling circuit in the above-mentioned embodiments. Similarly, the temperature sampling has high accuracy and reliability, thereby the accuracy and reliability of the temperature measurement of the IGBT are high.

[0055] by Figure 3Taking the temperature sampling circuit based on IGBT as an example, it can be placed in the GBT power circuit to detect the junction temperature of the IGBT to ensure that its junction temperature does not exceed the maximum limit specified in the manual. Specifically, the first operational amplifier U1 and the second operational amplifier U2 select TI-TLV9002 model operational amplifiers, and the positive temperature coefficient PTC thermistor selects PT1000. The first resistor R1, the positive temperature coefficient PTC thermistor, the second resistor R3, and the third resistor R4 form a bridge resistor network. The first resistor R1 and the first operational amplifier U1 form a high-precision constant current source excitation signal. The current passing through the positive temperature coefficient PTC thermistor is the constant current source value. The voltage value of the output terminal TEM-N of the first operational amplifier U1 changes with the change of temperature. In this embodiment, within the temperature range of -50℃-200℃, the voltage of the output terminal TEM-N of the first operational amplifier U1 varies from -0.85V to -1.90V.

[0056] The second resistor R3, the third resistor R4, the second operational amplifier U2, the fourth resistor R5 and the fifth resistor R6 form a reverse amplifier circuit, wherein the reference voltage provided by the reference power supply port VREF and the voltage of the output terminal TEMP-N of the constant current source excitation subcircuit 211 act on the voltage of the connection node of the second resistor R3 and the third resistor R4 as the voltage signal of the same-direction input terminal of the second operational amplifier U2, and its equivalent voltage is 0.096V-0.84V. The reverse amplifier circuit amplifies the voltage signal of the same-direction input terminal, and its amplification factor is 5.35 times, thereby amplifying to 0.5V-4.5V.

[0057] A low-pass filter is formed by using filter resistor R7 and filter capacitor C3, and its cut-off frequency fc=1 / 2*pi*R*C, where R is equal to the resistance of filter resistor R7, and C is equal to the capacitance of filter capacitor C3. The output voltage of the second operational amplifier U2 passes through a low-pass filter to filter out all the noise of the signal exceeding fc, and then outputs it to the AD conversion port of the control chip. By designing the output voltage range to be 0.5V~4.5V, the requirement of 0V-5V of the AD conversion port is met, and no additional voltage protection device is required. In this embodiment, fc is set to 1kHz, and its cut-off frequency can be adjusted according to actual needs later.

[0058] The temperature sampling circuit based on IGBT in this embodiment has higher linearity in the full temperature range (-50 to 200°C). Figure 4 As shown, it can more intuitively reflect the relationship between temperature and voltage, and has high measurement accuracy, so it can more accurately measure the junction temperature of the IGBT.

[0059] 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.

[0060] 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 based on IGBT, characterized in that: include: A sampling circuit, comprising an IGBT with an integrated thermistor, a first resistor and a constant current source excitation subcircuit, wherein the constant current source excitation subcircuit comprises an input end and an output end, the thermistor integrated in the IGBT is connected in series with the first resistor to obtain a first branch, one end of the first resistor in the first branch is connected to a reference power supply port, one end of the thermistor is connected to the output end of the constant current source excitation subcircuit, and a node connecting the first resistor and the thermistor is connected to the input end of the constant current source excitation subcircuit; 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, and one end of the second branch is connected to the reference power port, and the other end is connected to the output end of the constant current source excitation subcircuit, the input end of the level conversion subcircuit is connected to the node where the second resistor and the third resistor are connected, the output end of the level conversion subcircuit is connected to the output filter circuit, and the level conversion subcircuit performs level conversion on the voltage signal input from the input end and outputs the voltage signal; An output filter circuit, one end of which is connected to the output end of the level conversion sub-circuit, and the other end of which is connected to a temperature detector. The output filter circuit filters the input voltage signal and outputs it to the temperature detector.

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

3. The IGBT-based temperature sampling circuit according to claim 1, characterized in that: The constant current source excitation subcircuit includes a first operational amplifier, the inverting input terminal of the first operational amplifier serves as the input terminal of the constant current source excitation subcircuit, and is connected to the node where the first resistor and the thermistor are connected, the same-direction input terminal of the first operational amplifier is grounded, and the output terminal of the first operational amplifier serves as the output terminal of the constant current source excitation subcircuit, and is connected to one end of the thermistor in the first branch and one end of the third resistor in the second branch.

4. The IGBT-based temperature sampling circuit according to claim 3, characterized in that: The constant current source excitation subcircuit also includes a first decoupling capacitor, one end of the first decoupling capacitor is connected to the positive power supply terminal of the first operational amplifier, and the other end of the first decoupling capacitor is grounded.

5. The IGBT-based 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.

6. The IGBT-based temperature sampling circuit according to any one of claims 1 to 5, characterized in that: The level conversion sub-circuit includes a second operational amplifier, a fourth resistor and a fifth resistor. The same-direction input terminal of the second operational amplifier serves as the input terminal of the level conversion sub-circuit and is connected to a node where the second resistor and the third resistor are connected. The reverse input terminal of the second operational amplifier is connected to one end of the fourth resistor and one end of the fifth resistor. The other end of the fourth resistor is grounded. The other end of the fifth resistor is connected to the output terminal of the second operational amplifier. The output terminal of the second operational amplifier serves as the output terminal of the level conversion sub-circuit and is connected to the output filter circuit.

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

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

Images