Multistage high-precision temperature detection circuit

Abstract

The utility model provides a multi-stage high-precision temperature detection circuit, which comprises a voltage division sampling module, a first switch resistor module and a second switch resistor module, and is based on different state combinations of a first control signal and a second control signal. The total resistance value of a pull-up resistor composed of the divider resistor, the first resistor and the second resistor can be effectively adjusted, based on resistance value adjustment of the pull-up resistor, the multi-stage high-precision temperature detection circuit has more than two different detection temperature precision highest points, and by combining design adjustment of the corresponding resistance value, the detection precision of the multi-stage high-precision temperature detection circuit is improved. More than two detection temperature precision highest points are averagely distributed in a temperature detection range, the temperature detection range is divided into more than two temperature sections, the middle point of each temperature section corresponds to one detection temperature precision highest point, the temperature detection range is divided more finely, and the temperature detection precision is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of temperature sensing test, in particular to a multi-stage high-precision temperature detection circuit. Background Art

[0002] With the development of intelligent vehicles, extended-range hybrid vehicles have higher and higher requirements for the sampling accuracy of various sensors. Take the temperature sensor of a certain fuel tank as an example. It is an NTC (Negative Temperature Coefficient) thermistor sensor. When the sensor is at -40℃, the resistance characteristic of the sensor is 110K ohms; when the sensor is at 150℃, the resistance characteristic of the sensor is 47 ohms. Before the sensor is connected to the controller, the pull-up resistor and the variable resistance of the sensor are used for voltage division sampling. The obtained sampling signal is then transmitted to the analog-to-digital conversion sampling port of the MCU (MicroController Unit). The current resistance of the sensor can be calculated, and then the current ambient temperature of the sensor can be obtained by the table lookup method.

[0003] However, in the circuit design of traditional automobiles, in the temperature range of -40℃~150℃, in order to ensure accurate feedback control, the corresponding temperature detection accuracy needs to meet the accuracy requirement of ±1%, and the temperature detection error does not exceed ±1℃. However, the existing temperature detection technology solutions have only one or two high-precision points for temperature detection in the entire temperature range, and there are fewer high-precision points for temperature detection. The farther away from the high-precision points for temperature detection, the lower the temperature detection accuracy, and the corresponding detection error may exceed ±1℃.

[0004] In view of this, a simple and high-precision temperature sensing test technology solution is urgently needed. Utility Model Content

[0005] In view of the shortcomings of the prior art mentioned above, the purpose of the utility model is to provide a multi-stage high-precision temperature detection technical solution, combining a voltage divider sampling module, a first switch resistor module and a second switch resistor module to design a multi-stage high-precision temperature detection circuit, based on different state combinations of the first control signal and the second control signal, the total resistance of the pull-up resistor composed of the voltage divider resistor, the first resistor and the second resistor can be effectively adjusted, based on the resistance adjustment of the pull-up resistor, the multi-stage high-precision temperature detection circuit has more than two different detection temperature accuracy points, and combined with the design adjustment of the corresponding resistance value, the more than two detection temperature accuracy points are evenly distributed within the temperature detection range, and the temperature detection range is divided into more than two temperature segments, the midpoint of each temperature segment corresponds to a detection temperature accuracy point, the temperature detection range is more finely divided, and the temperature measurement accuracy is improved.

[0006] In order to achieve the above-mentioned purpose and other related purposes, the technical solution provided by the utility model is as follows.

[0007] A multi-stage high-precision temperature detection circuit, comprising:

[0008] The voltage-dividing sampling module includes a voltage-dividing resistor and a thermistor connected in series, and performs voltage-dividing sampling on the power supply voltage to obtain a sampling voltage related to the ambient temperature;

[0009] A first switch resistance module, connected to the voltage-dividing sampling module, comprising a first resistor, the first resistor being arranged in parallel with the voltage-dividing resistor via a first parallel branch, and the first parallel branch being controlled on and off by a first control signal;

[0010] The second switch resistor module is connected to the voltage-dividing sampling module and includes a second resistor. The second resistor is connected in parallel with the voltage-dividing resistor via a second parallel branch, and the second parallel branch is controlled on and off by a second control signal.

[0011] Optionally, the power supply voltage is grounded after passing through the voltage-dividing resistor and the thermistor which are connected in series in sequence, and a common end of the thermistor and the voltage-dividing resistor outputs the sampling voltage.

[0012] Optionally, the first switch resistor module also includes a first switch tube, a second switch tube, a third resistor, a fourth resistor and a fifth resistor. The first control signal is grounded after passing through the third resistor and the fourth resistor connected in series in sequence. The input end of the first switch tube is grounded, the control end of the first switch tube is connected to the common end of the third resistor and the fourth resistor, the output end of the first switch tube is connected to the control end of the second switch tube, the output end of the first switch tube is also connected to the power supply voltage after passing through the fifth resistor connected in series, the input end of the second switch tube is connected to the sampling voltage after passing through the first resistor connected in series, and the output end of the second switch tube is connected to the power supply voltage.

[0013] Optionally, the second switch resistor module also includes a third switch tube, a fourth switch tube, a sixth resistor, a seventh resistor and an eighth resistor. The second control signal is grounded after being connected in series with the sixth resistor and the seventh resistor in sequence. The input end of the third switch tube is grounded. The control end of the third switch tube is connected to the common end of the sixth resistor and the seventh resistor. The output end of the third switch tube is connected to the control end of the fourth switch tube. The output end of the third switch tube is also connected to the power supply voltage after being connected in series with the eighth resistor. The input end of the fourth switch tube is connected to the sampling voltage after being connected in series with the second resistor. The output end of the fourth switch tube is connected to the power supply voltage.

[0014] Optionally, the first switch tube and the third switch tube are both NMOS tubes, and the second switch tube and the fourth switch tube are both PMOS tubes.

[0015] Optionally, the first switch tube and the third switch tube are both NPN tubes, and the second switch tube and the fourth switch tube are both PNP tubes.

[0016] Optionally, the resistance value of the voltage-dividing resistor is greater than the resistance value of the second resistor, and the resistance value of the second resistor is greater than the resistance value of the first resistor.

[0017] Optionally, the multi-stage high-precision temperature detection circuit also includes a sampling output module, and the sampling voltage is input to the microcontroller through the sampling output module. The microcontroller is configured to: calculate the real-time resistance value of the thermistor based on the sampling voltage, and determine the ambient temperature by looking up a table.

[0018] Optionally, the microcontroller is also configured to: output the first control signal and the second control signal, and adjust the on-off state of the first parallel branch and the second parallel branch based on multiple different state combinations of the first control signal and the second control signal, so as to adjust the total resistance of the pull-up resistor composed of the voltage divider resistor, the first resistor and the second resistor, and divide the temperature detection range into three temperature segments. The resistance values ​​of the pull-up resistors corresponding to different temperature segments are different, so that the highest accuracy points of the detection temperatures corresponding to different temperature segments are different.

[0019] Optionally, the microcontroller is configured to: at the beginning, set the first control signal and the second control signal to a first state, turn off the first parallel branch and the second parallel branch, only perform sampling through the voltage divider sampling module, and calculate and determine the ambient temperature through the microcontroller, and determine the temperature segment to which the ambient temperature belongs through the microcontroller, determine whether it is necessary to readjust the resistance of the pull-up resistor and detect the temperature again, and if so, adjust the states of the first control signal and the second control signal accordingly based on the resistance of the pull-up resistor corresponding to the temperature segment.

[0020] As described above, the multi-stage high-precision temperature detection circuit of the utility model has at least the following beneficial effects:

[0021] A multi-stage high-precision temperature detection circuit is designed by combining a voltage-dividing sampling module, a first switch resistor module and a second switch resistor module. Based on different state combinations of a first control signal and a second control signal, the total resistance of a pull-up resistor composed of a voltage-dividing resistor, a first resistor and a second resistor can be effectively adjusted. When the resistance of the thermistor is equal to that of the corresponding pull-up resistor, the accuracy of the corresponding temperature detection point is the highest. Therefore, based on the resistance adjustment of the pull-up resistor, the multi-stage high-precision temperature detection circuit has more than two different highest points of detection temperature accuracy. Combined with the design adjustment of the corresponding resistance value, the more than two highest points of detection temperature accuracy are evenly distributed within the temperature detection range, and the temperature detection range is divided into more than two temperature segments, and the midpoint of each temperature segment corresponds to a highest point of detection temperature accuracy. The temperature detection range is divided more finely. When detecting the temperature, an approximate temperature detection is first performed to find the temperature segment corresponding to the real-time temperature. Then, based on the control of the first control signal and the second control signal, the temperature is adjusted to the corresponding highest point of detection temperature accuracy before the temperature test is performed, thereby improving the temperature measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is a circuit diagram of a primary temperature detection circuit in the prior art.

[0023] Figure 2 Shown is a circuit diagram of a secondary temperature detection circuit in the prior art II.

[0024] Figure 3 Shown is a circuit structure schematic diagram of a multi-stage high-precision temperature detection circuit in the utility model.

[0025] Figure 4 Shown is a circuit diagram of a multi-stage high-precision temperature detection circuit in an optional embodiment of the utility model.

[0026] Figure 5 Shown is a circuit diagram of a multi-stage high-precision temperature detection circuit in another optional embodiment of the utility model. DETAILED DESCRIPTION

[0027] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] See also Figures 1 to 5. It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the utility model in a schematic manner, so the diagram only shows the components related to the utility model rather than being drawn according to the number, shape and size of the components during actual implementation. During actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated. The structure, proportion, size, etc. illustrated in the drawings attached to this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the restrictive conditions for the implementation of the utility model, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the utility model without affecting the effect and purpose that can be achieved by the utility model.

[0029] As mentioned in the background technology above, the inventors have found that the existing temperature detection technology solutions have only one or two points with high temperature detection accuracy in the entire temperature range, and there are fewer points with high temperature detection accuracy. The farther away from the points with high temperature detection accuracy, the lower the temperature detection accuracy, and the corresponding detection error may exceed ±1°C.

[0030] In detail, Figure 1 As shown, the prior art 1 is a primary temperature detection circuit, which includes a voltage-dividing resistor R0, a thermistor Rs, an output resistor Rt, a first capacitor C1 and a second capacitor C2. The voltage-dividing resistor R0 and the thermistor Rs constitute a resistor voltage-dividing network, and the power supply voltage VDDSA is sampled to obtain a sampled voltage Vs. The output resistor Rt, the first capacitor C1 and the second capacitor C2 constitute a sampling output structure, and the sampled voltage Vs is transmitted to the microcontroller MCU after filtering and current limiting processing of the sampling output structure. When the ambient temperature of the thermistor Rs changes, the resistance of the thermistor Rs changes, causing the sampled voltage Vs to change accordingly. The microcontroller MCU can calculate the resistance of the thermistor Rs according to the sampled voltage Vs, and then obtain the ambient temperature of the thermistor Rs by looking up the table method, so that the ambient temperature detection is realized.

[0031] Among them, the pull-up resistor in the resistor voltage divider network is only the voltage divider resistor R0, and the resistance of the voltage divider resistor R0 is fixed (such as 1K ohm). The signal of the sampling voltage Vs will change with the temperature. When the resistance of the thermistor Rs is equal to that of the corresponding pull-up resistor, the accuracy of the corresponding temperature detection point is the highest. Therefore, this makes Figure 1 The primary temperature detection circuit shown has only one temperature detection point with higher accuracy within the temperature detection range. For example, when the resistance of the voltage divider resistor R0 is 1K ohms, the temperature detection point with the highest accuracy is 45°C. As the temperature rises and falls, the deviation of the detection accuracy increases, and thus the detection accuracy requirement of ±1°C cannot be met.

[0032] In detail, Figure 2 As shown, the second prior art is a secondary temperature detection circuit, which includes an NMOS tube N1, a PMOS tube P1, a voltage-dividing resistor R0, a thermistor Rs, a first resistor R1, a voltage-dividing resistor R01, a voltage-dividing resistor R02, a current-limiting resistor R03, an output resistor Rt, a first capacitor C1 and a second capacitor C2. The voltage-dividing resistor R0 and the thermistor Rs constitute a resistor voltage-dividing network, and the power supply voltage VDDSA is sampled to obtain a sampled voltage Vs. The output resistor Rt, the first capacitor C1 and the second capacitor C2 constitute a sampling output structure. The sampled voltage Vs is transmitted to the microcontroller MCU after filtering and current limiting processing of the sampling output structure. The NMOS tube N1, the PMOS The tube P1, the voltage-dividing resistor R01, the voltage-dividing resistor R02 and the current-limiting resistor R03 form a switch resistor structure. The microcontroller MCU outputs a first control signal Ctrl_1. The first control signal Ctrl_1 is applied to the gate of the NMOS tube N1 after being divided by the resistor voltage-dividing network composed of the voltage-dividing resistor R01 and the voltage-dividing resistor R02, so as to perform switch control on the NMOS tube N1. The switch state of the NMOS tube N1 further determines the switch state of the PMOS tube P1. Therefore, the on-off state of the parallel path where the first resistor R1 is located can be controlled by the first control signal Ctrl_1, so that the first resistor R1 can be connected in parallel to the voltage-dividing resistor R0 or not connected.

[0033] Among them, when the first control signal Ctrl_1 is at a low level, the first resistor R1 is not connected in parallel with the voltage-dividing resistor R0, and the pull-up resistor in the resistor voltage-dividing network is only the voltage-dividing resistor R0, such as 10K ohms, and the corresponding detection temperature accuracy is at a maximum of 0°C; when the first control signal Ctrl_1 is at a high level, the NMOS tube N and the PMOS tube P1 are turned on, the first resistor R1 is not connected in parallel with the voltage-dividing resistor R0, and the pull-up resistor in the resistor voltage-dividing network is actually the voltage-dividing resistor R0 and the first resistor R1 set in parallel, and the corresponding resistance value is 909 ohms, and the detection temperature accuracy is at a maximum of 50°C.

[0034] So, in such Figure 2 In the secondary temperature detection circuit shown, although there are two temperature points with higher detection accuracy between -40℃-150℃, when the two temperature points with higher detection accuracy are 0℃ and 50℃, the temperature detection accuracy within the temperature range of -40℃-80℃ can barely be met, while the temperature within the temperature range of 80℃-150℃ deviates far from 0℃ and 50℃, and the detection error within the corresponding range is greater than ±1℃, which still cannot meet the detection accuracy requirement of ±1℃.

[0035] Based on this, the utility model proposes a multi-stage high-precision temperature detection technical solution: a multi-stage high-precision temperature detection circuit is designed by combining a voltage divider sampling module, a first switch resistor module and a second switch resistor module, and based on different state combinations of a first control signal and a second control signal, the first resistor provided by the first switch resistor module and the second resistor provided by the second switch resistor module are adjusted relative to the parallel access state of the voltage divider resistor in the voltage divider sampling module to adjust the total resistance value of the pull-up resistor composed of the voltage divider resistor, the first resistor and the second resistor, so that the pull-up resistor has more than two different resistance values, and based on the design of more than two different resistance values ​​of the pull-up resistor, more than two are present within the temperature detection range. The detection temperature accuracy is higher, and combined with the design adjustment of the corresponding resistance value, more than two detection temperature accuracy points are evenly distributed in the temperature detection range, and then the temperature detection range is more finely divided, and the temperature detection range is divided into more than two temperature segments, and the midpoint of each temperature segment corresponds to a detection temperature accuracy point. When detecting the temperature, an approximate temperature detection is first performed to find the temperature segment corresponding to the real-time temperature, and then based on the control of the first control signal and the second control signal, the temperature is adjusted to the corresponding detection temperature accuracy point before the temperature test is performed. The number of temperature division segments is more and the division is more refined. The temperature test results in the corresponding temperature segments are more accurate, which improves the temperature measurement accuracy.

[0036] First, if Figure 3 As shown, the utility model provides a multi-stage high-precision temperature detection circuit, which includes:

[0037] The voltage division sampling module 1 includes a voltage division resistor R0 and a thermistor Rs connected in series, and performs voltage division sampling on the power supply voltage VDDSA to obtain a sampling voltage Vs related to the ambient temperature;

[0038] The first switch resistor module 2 is connected to the voltage-dividing sampling module 1 and includes a first resistor R1, which is connected in parallel with the voltage-dividing resistor R0 through a first parallel branch, and the first parallel branch is controlled on and off by a first control signal Ctrl_1;

[0039] The second switch resistor module 3 is connected to the voltage-dividing sampling module 1 and includes a second resistor R2. The second resistor R2 is connected in parallel with the voltage-dividing resistor R0 via a second parallel branch, and the second parallel branch is controlled on and off by a second control signal Ctrl_2.

[0040] In detail, Figure 3 As shown, in the voltage-dividing sampling module 1 , the power supply voltage VDDSA is connected to the ground GND after passing through the voltage-dividing resistor R0 and the thermistor Rs connected in series in sequence, and the common end of the thermistor Rs and the voltage-dividing resistor R0 outputs the sampling voltage Vs.

[0041] In detail, Figure 3As shown, the first switch resistor module 2 at least includes a second switch tube K1 and a first resistor R1. The input end of the second switch tube K1 is connected to the sampling voltage Vs via the first resistor R1 connected in series. The output end of the second switch tube K1 is connected to the power supply voltage VDDSA. The control end of the second switch tube K1 is connected to the converted first control signal Ctrl_1. The first parallel branch is controlled to be on and off by the first control signal Ctrl_1.

[0042] In more detail, Figure 4 As shown, in an optional embodiment of the utility model, the first switch resistor module 2 also includes a first switch tube Q1, a third resistor R3, a fourth resistor R4 and a fifth resistor R5. The first control signal Ctrl_1 is connected to the ground GND after passing through the third resistor R3 and the fourth resistor R4 connected in series in sequence. The input end of the first switch tube Q1 is connected to the ground GND, the control end of the first switch tube Q1 is connected to the common end of the third resistor R3 and the fourth resistor R4, the output end of the first switch tube Q1 is connected to the control end of the second switch tube K1, the output end of the first switch tube Q1 is also connected to the power supply voltage VDDSA after passing through the fifth resistor R5 connected in series, the input end of the second switch tube K1 is connected to the sampling voltage Vs after passing through the first resistor R1 connected in series, and the output end of the second switch tube K1 is connected to the power supply voltage VDDSA.

[0043] In detail, Figure 3 As shown, the second switch resistor module 3 at least includes a fourth switch tube K2 and a second resistor R2, the input end of the fourth switch tube K2 is connected to the sampling voltage Vs via the second resistor R2 connected in series, the output end of the fourth switch tube K2 is connected to the power supply voltage VDDSA, and the control end of the fourth switch tube K2 is connected to the converted second control signal Ctrl_2, and the second parallel branch is controlled to be on and off by the second control signal Ctrl_2.

[0044] In more detail, Figure 4 As shown, in an optional embodiment of the utility model, the second switch resistor module 3 includes a third switch tube Q2, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8, the second control signal Ctrl_2 is connected to the ground GND after passing through the sixth resistor R6 and the seventh resistor R7 connected in series in sequence, the input end of the third switch tube Q2 is connected to the ground GND, the control end of the third switch tube Q2 is connected to the common end of the sixth resistor R6 and the seventh resistor R7, the output end of the third switch tube Q2 is connected to the control end of the fourth switch tube K2, the output end of the third switch tube Q2 is further connected to the power supply voltage VDDSA after passing through the eighth resistor R8 connected in series, the input end of the fourth switch tube K2 is connected to the sampling voltage Vs after passing through the second resistor R2 connected in series, and the output end of the fourth switch tube K2 is connected to the power supply voltage VDDSA.

[0045] The resistance of the voltage-dividing resistor R0 is greater than the resistance of the second resistor R2, and the resistance of the second resistor R2 is greater than the resistance of the first resistor R1. For example, in an optional embodiment of the present invention, the resistance of the voltage-dividing resistor R0 is 10K ohms, the resistance of the second resistor R2 is 1K ohms, and the resistance of the first resistor R1 is 200 ohms.

[0046] In detail, Figure 3 As shown, the multi-stage high-precision temperature detection circuit also includes a sampling output module 4, and the sampling voltage Vs is input to the microcontroller MCU through the sampling output module 4. The microcontroller MCU is configured to: calculate the real-time resistance value of the thermistor Rs based on the sampling voltage Vs, and determine the ambient temperature by looking up the table.

[0047] In more detail, Figure 4 As shown, in an optional embodiment of the utility model, the sampling output module 4 includes an output resistor Rt, a first capacitor C1 and a second capacitor C2, the first end of the first capacitor C1 is grounded GND, the second end of the first capacitor C1 is connected to the sampling voltage Vs, the sampling voltage Vs is transmitted to the analog-to-digital conversion sampling port of the microcontroller MCU through the serially connected output resistor Rt, the first end of the second capacitor C2 is grounded GND, and the second end of the second capacitor C2 is connected to the analog-to-digital conversion sampling port of the microcontroller MCU.

[0048] In detail, Figure 3 and Figure 4 As shown, the microcontroller MCU is also configured to: output a first control signal Ctrl_1 and a second control signal Ctrl_2, and adjust the on-off state of the first parallel branch and the second parallel branch based on multiple different state combinations of the first control signal Ctrl_1 and the second control signal Ctrl_2, so as to adjust the total resistance value of the pull-up resistor composed of the voltage divider resistor R0, the first resistor R1 and the second resistor R2, and divide the temperature detection range into three temperature segments. The resistance values ​​of the pull-up resistors corresponding to different temperature segments are different, so that the highest accuracy points of the detection temperatures corresponding to different temperature segments are different.

[0049] In more detail, Figure 4As shown, in an optional embodiment of the utility model, the resistance of the voltage-dividing resistor R0 is 10K ohms, the resistance of the second resistor R2 is 1K ohms, and the resistance of the first resistor R1 is 200 ohms. When the first control signal Ctrl_1 and the second control signal Ctrl_2 are both at a low level (first state), the first switch Q1 and the third switch Q2 are turned off, so that the second switch K1 and the fourth switch K4 are also turned off, the first parallel branch and the second parallel branch are both disconnected, the first resistor R1 and the second resistor R2 are not connected in parallel to the voltage-dividing resistor R0, the pull-up resistor only includes the voltage-dividing resistor R0, the resistance of the pull-up resistor is 10K ohms, and the corresponding detection temperature accuracy The highest point is 0°C; when the first control signal Ctrl_1 is at a low level (first state) and the second control signal Ctrl_2 is at a high level (second state), the first switch Q1 is turned off, and the third switch Q2 is turned off. When the switch Q2 is turned on, the second switch K1 is turned off and the fourth switch K4 is turned on, the first parallel branch is disconnected and the second parallel branch is turned on, and only the second resistor R2 is connected in parallel to the voltage-dividing resistor R0, the pull-up resistor includes the voltage-dividing resistor R0 and the second resistor R2, the resistance of the pull-up resistor is 909 ohms, and the corresponding highest point of detection temperature accuracy is 50°C; when the first control signal Ctrl_1 and the second control signal Ctrl_2 are both high level (second state), the first switch Q1 and the third switch Q2 are turned on, so that the second switch K1 and the fourth switch K4 are also turned on, the first parallel branch and the second parallel branch are both turned on, the first resistor R1 and the second resistor R2 are connected in parallel to the voltage-dividing resistor R0, the pull-up resistor includes the voltage-dividing resistor R0, the first resistor R1 and the second resistor R2, the resistance of the pull-up resistor is 163 ohms, and the corresponding highest point of detection temperature accuracy is 100°C.

[0050] Thus, based on the above three different combinations of the first control signal Ctrl_1 and the second control signal Ctrl_2, three detection temperature accuracy points of 0°C, 50°C and 100°C can be obtained, wherein the detection temperature accuracy point of 0°C can cover the temperature range of -40°C to 20°C, the detection temperature accuracy point of 50°C can cover the temperature range of 20°C to 80°C, and the detection temperature accuracy point of 100°C can cover the temperature range of 80°C to 150°C. That is to say, under the control of the two control signals, this circuit design has three sequential distributions within the temperature range of -40°C to 150°C and Accurately cover the temperature points with higher detection accuracy, and divide the temperature range of -40℃ ~ 150℃ into three temperature segments. Compared with one temperature point with higher detection accuracy (such as 45℃) of the first-level temperature detection, the full-range temperature of -40℃ ~ 150℃ is measured, or two temperature points with higher detection accuracy (such as 0℃ and 50℃) of the second-level temperature detection, the full-range temperature of -40℃ ~ 150℃ is measured. The temperature test range corresponding to each temperature segment has a smaller deviation distance than the corresponding temperature point with higher detection accuracy, and the temperature test accuracy within the corresponding range is higher, which can meet the test accuracy requirement of ±1℃.

[0051] Optionally, in an optional embodiment of the present invention, the power supply voltage VDDSA and the power supply voltage of the microcontroller MCU are the same power supply voltage, and the precisions of the voltage divider resistor R0, the first resistor R1 and the second resistor R2 are all 0.1%.

[0052] In detail, Figure 3 and Figure 4 As shown, the microcontroller MCU is also configured as follows: at the beginning, the first control signal Ctrl_1 and the second control signal Ctrl_2 are both set to the first state, the first parallel branch and the second parallel branch are turned off, sampling is performed only through the voltage divider sampling module 1, and the ambient temperature is determined by calculation through the microcontroller MCU, and the temperature segment to which the ambient temperature belongs is determined by the microcontroller MCU to determine whether it is necessary to readjust the resistance value of the pull-up resistor and detect the temperature again. If so, the states of the first control signal Ctrl_1 and the second control signal Ctrl_2 are adjusted accordingly based on the resistance value of the pull-up resistor corresponding to the temperature segment.

[0053] In more detail, Figure 4As shown, in an optional embodiment of the utility model, the microcontroller MCU is also configured as follows: at the beginning, the first control signal Ctrl_1 and the second control signal Ctrl_2 are both set to a low level, the first parallel branch and the second parallel branch are turned off, the first resistor R1 and the second resistor R2 are not connected in parallel to the voltage divider resistor R0, the pull-up resistor only includes the voltage divider resistor R0, and the voltage divider sampling is performed only through the voltage divider sampling module 1, and the ambient temperature is calculated and determined by the microcontroller MCU, and the temperature segment to which the ambient temperature belongs is determined by the microcontroller MCU to determine whether it is necessary to readjust the resistance value of the pull-up resistor and detect the temperature again. If so, the states of the first control signal Ctrl_1 and the second control signal Ctrl_2 are adjusted accordingly based on the resistance value of the pull-up resistor corresponding to the temperature segment.

[0054] Among them, when the first control signal Ctrl_1 and the second control signal Ctrl_2 are both set to a low level, the higher point of temperature detection accuracy is 0°C, which can accurately cover the ambient temperature in the temperature range of -40°C to 20°C. If the initially measured ambient temperature falls within the temperature range of -40°C to 20°C, there is no need to adjust the resistance of the pull-up resistor and there is no need to detect the temperature again, and the temperature detection accuracy of the test has met the requirements; if the initially measured ambient temperature falls into other temperature ranges outside the temperature range of -40°C to 20°C, it indicates that the tested temperature does not meet the accuracy requirements, and it is necessary to find the corresponding temperature range and the corresponding higher point of detection temperature accuracy, adjust the resistance of the pull-up resistor to the corresponding resistance, and detect the temperature again.

[0055] It can be understood that if the initially measured ambient temperature falls near the critical point of the temperature range of -40℃ ~ 20℃ and the temperature range of 20℃ ~ 80℃, such as -19℃, -20℃ and -21℃, you can flexibly choose according to the situation. You can test again after adjustment and calculate the average of the two tests, or you can stop testing.

[0056] It should be noted that in Figure 4 In the embodiment shown, the first switch tube Q1 and the third switch tube Q2 are both NMOS tubes, and the second switch tube K2 and the fourth switch tube K4 are both PMOS tubes. However, the circuit topology of the multi-stage high-precision temperature detection circuit in the present invention is not limited to the following. Figure 4 The circuit topology shown may also include more or fewer components such as resistors and capacitors. The corresponding switch tube is not limited to MOS tubes, but may also be transistors such as triodes. The corresponding thermistor Rs is not limited to negative temperature coefficient thermistors, but may also be positive temperature coefficient thermistors, which are not limited here.

[0057] In detail, in another optional embodiment of the present invention, as Figure 5As shown, the first switch tube Q1 and the third switch tube Q2 are both NPN tubes, the second switch tube K1 and the fourth switch tube K2 are both PNP tubes, and the sampling output module 4 only includes an output resistor Rt and a first capacitor C1, and no longer includes a second capacitor C2. The detailed circuit topology and working principle can be referred to as Figure 4 The illustrated embodiment is analyzed and explained, which will not be described in detail here.

[0058] In addition, it should be emphasized that the high level or low level of the first control signal Ctrl_1 and the second control signal Ctrl_2 output by the microcontroller MCU is a relatively fixed voltage value in this field, such as the high level voltage is 3.3V or 5V, and the low level voltage is 0V or 0.1V.

[0059] At the same time, it should be noted that in the present invention, the first control signal Ctrl_1 and the second control signal Ctrl_2 are not limited to the above three different combinations, but also have a fourth state combination, that is, the first control signal Ctrl_1 is high level and the second control signal Ctrl_2 is low level, and the corresponding detection temperature precision can be up to four points. Based on the design adjustment of the resistance value, the temperature detection range can be divided into 4 sections more finely, and the design can be flexibly selected according to actual needs, which is not limited here.

[0060] Secondly, the utility model also provides a vehicle, which includes the above-mentioned multi-stage high-precision temperature detection circuit. The above-mentioned multi-stage high-precision temperature detection circuit can be used in multiple functional modules of the vehicle, such as transmission oil temperature detection, engine intake temperature detection and motor temperature detection.

[0061] The vehicle includes a transmission. The oil temperature sensor of the transmission is located on the valve plate in the oil pan of the automatic transmission. It is mainly used to detect the temperature of the transmission hydraulic oil. As an electronic control unit, it is the basis of shift control, oil pressure control and locking clutch air. Its interior is mainly a thermistor with a negative temperature coefficient. The higher the temperature, the lower the resistance. Its resistance changes with temperature. The microcontroller MCU measures the temperature of the automatic transmission hydraulic oil according to the change of its resistance. In an optional embodiment of the utility model, the oil temperature of the transmission is detected and collected using the above-mentioned multi-stage high-precision temperature detection circuit. The multi-stage high-precision temperature detection circuit based on the above-mentioned multi-stage precision control test can effectively improve the temperature test accuracy, thereby improving the feedback control accuracy of the transmission.

[0062] The extended-range hybrid vehicle also includes an engine, and a vehicle intake temperature sensor is provided on the intake pipe or intake valve of the engine to monitor the temperature change during the vehicle intake process and transmit these data to the engine control system, and the engine control system adjusts the engine intake volume and fuel injection volume according to these data to achieve the best power output and fuel economy. In an optional embodiment of the utility model, the engine intake temperature is detected and collected using the above-mentioned multi-stage high-precision temperature detection circuit. The multi-stage high-precision temperature detection circuit based on the above-mentioned multi-stage precision control test can effectively improve the temperature test accuracy, thereby improving the feedback accuracy of the engine intake temperature, and facilitating the realization of the best power output and fuel economy.

[0063] The vehicle also includes a motor, which is the core component of the new energy vehicle that converts electrical energy into kinetic energy. The power level of hybrid vehicles, electric vehicles / buses ranges from 10KW to 200KW. By monitoring the temperature of the motor, the motor controller can adopt different control strategies in different states to protect the entire power unit. In an optional embodiment of the utility model, the real-time temperature of the motor is detected and collected using the above-mentioned multi-stage high-precision temperature detection circuit. The multi-stage high-precision temperature detection circuit based on the above-mentioned multi-stage precision control test can effectively improve the temperature test accuracy, thereby improving the feedback accuracy of the motor temperature, and facilitating the optimization of the motor output power and control strategy.

[0064] In summary, in the multi-stage high-precision temperature detection circuit and vehicle provided by the utility model, the multi-stage high-precision temperature detection circuit is designed in combination with the voltage-dividing sampling module, the first switch resistor module and the second switch resistor module. Based on the different state combinations of the first control signal and the second control signal, the total resistance of the pull-up resistor composed of the voltage-dividing resistor, the first resistor and the second resistor can be effectively adjusted. When the resistance of the thermistor is equal to that of the corresponding pull-up resistor, the accuracy of the corresponding temperature detection point is the highest. Therefore, based on the resistance adjustment of the pull-up resistor, the multi-stage high-precision temperature detection circuit has more than two different highest points of detection temperature accuracy. Combined with the design adjustment of the corresponding resistance value, the more than two highest points of detection temperature accuracy are evenly distributed within the temperature detection range, and the temperature detection range is divided into more than two temperature segments, and the midpoint of each temperature segment corresponds to a highest point of detection temperature accuracy. The temperature detection range is divided more finely. When detecting the temperature, an approximate temperature detection is first performed to find the temperature segment corresponding to the real-time temperature. Then, based on the control of the first control signal and the second control signal, the temperature is adjusted to the corresponding highest point of detection temperature accuracy before the temperature test is performed, thereby improving the temperature measurement accuracy.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A multi-stage high-precision temperature detection circuit, characterized in that: include: The voltage-dividing sampling module includes a voltage-dividing resistor and a thermistor connected in series, and performs voltage-dividing sampling on the power supply voltage to obtain a sampling voltage related to the ambient temperature; A first switch resistance module, connected to the voltage-dividing sampling module, comprising a first resistor, the first resistor being arranged in parallel with the voltage-dividing resistor via a first parallel branch, and the first parallel branch being controlled on and off by a first control signal; The second switch resistor module is connected to the voltage-dividing sampling module and includes a second resistor. The second resistor is connected in parallel with the voltage-dividing resistor via a second parallel branch, and the second parallel branch is controlled on and off by a second control signal.

2. The multi-stage high-precision temperature detection circuit according to claim 1, characterized in that: The power supply voltage is grounded after passing through the voltage-dividing resistor and the thermistor which are connected in series in sequence, and a common end of the thermistor and the voltage-dividing resistor outputs the sampling voltage.

3. The multi-stage high-precision temperature detection circuit according to claim 2, characterized in that: The first switch resistor module also includes a first switch tube, a second switch tube, a third resistor, a fourth resistor and a fifth resistor. The first control signal is connected to ground after passing through the third resistor and the fourth resistor connected in series in sequence. The input end of the first switch tube is grounded, the control end of the first switch tube is connected to the common end of the third resistor and the fourth resistor, the output end of the first switch tube is connected to the control end of the second switch tube, the output end of the first switch tube is also connected to the power supply voltage after passing through the fifth resistor connected in series, the input end of the second switch tube is connected to the sampling voltage after passing through the first resistor connected in series, and the output end of the second switch tube is connected to the power supply voltage.

4. The multi-stage high-precision temperature detection circuit according to claim 3, characterized in that: The second switch resistor module also includes a third switch tube, a fourth switch tube, a sixth resistor, a seventh resistor and an eighth resistor. The second control signal is connected to ground after passing through the sixth resistor and the seventh resistor connected in series in sequence. The input end of the third switch tube is grounded. The control end of the third switch tube is connected to the common end of the sixth resistor and the seventh resistor. The output end of the third switch tube is connected to the control end of the fourth switch tube. The output end of the third switch tube is also connected to the power supply voltage after passing through the eighth resistor connected in series. The input end of the fourth switch tube is connected to the sampling voltage after passing through the second resistor connected in series. The output end of the fourth switch tube is connected to the power supply voltage.

5. The multi-stage high-precision temperature detection circuit according to claim 4, characterized in that: The first switch tube and the third switch tube are both NMOS tubes, and the second switch tube and the fourth switch tube are both PMOS tubes.

6. The multi-stage high-precision temperature detection circuit according to claim 4, characterized in that: The first switch tube and the third switch tube are both NPN tubes, and the second switch tube and the fourth switch tube are both PNP tubes.

7. The multi-stage high-precision temperature detection circuit according to claim 1, characterized in that: The resistance value of the voltage-dividing resistor is greater than the resistance value of the second resistor, and the resistance value of the second resistor is greater than the resistance value of the first resistor.

8. The multi-stage high-precision temperature detection circuit according to claim 7, characterized in that: The multi-stage high-precision temperature detection circuit also includes a sampling output module, and the sampling voltage is input to the microcontroller through the sampling output module. The microcontroller is configured to: calculate the real-time resistance value of the thermistor based on the sampling voltage, and determine the ambient temperature by looking up a table.

9. The multi-stage high-precision temperature detection circuit according to claim 8, characterized in that: The microcontroller is also configured to: output the first control signal and the second control signal, and adjust the on-off state of the first parallel branch and the second parallel branch based on multiple different state combinations of the first control signal and the second control signal, so as to adjust the total resistance of the pull-up resistor composed of the voltage divider resistor, the first resistor and the second resistor, and divide the temperature detection range into three temperature segments. The resistance values ​​of the pull-up resistors corresponding to different temperature segments are different, so that the highest accuracy points of the detection temperatures corresponding to different temperature segments are different.

10. The multi-stage high-precision temperature detection circuit according to claim 9, characterized in that: The microcontroller is configured as follows: at the beginning, both the first control signal and the second control signal are set to a first state, the first parallel branch and the second parallel branch are turned off, sampling is performed only through the voltage divider sampling module, and the ambient temperature is determined by calculation by the microcontroller, and the temperature segment to which the ambient temperature belongs is determined by the microcontroller to determine whether it is necessary to readjust the resistance value of the pull-up resistor and detect the temperature again. If so, the states of the first control signal and the second control signal are adjusted accordingly based on the resistance value of the pull-up resistor corresponding to the temperature segment.

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