NTC high-precision temperature detection circuit

Abstract

This application relates to the field of power metering technology, and proposes an NTC high-precision temperature detection circuit, including: an NTC temperature sampling probe, a temperature sampling circuit, a VCC power supply, and a DSP; the temperature sampling circuit is connected to a reference voltage via the VCC power supply; the temperature sampling circuit includes an amplifier and a low-pass filter, and the sampling signal from the NTC temperature sampling probe is sent to the DSP after passing through the amplifier and low-pass filter. The DSP performs temperature detection based on the sampling signal and the reference voltage. By combining bridge arm voltage division and differential amplification, and with the design of connecting the power supply to the reference voltage, the accuracy and stability of the temperature sampling circuit are significantly improved, thereby achieving high-precision, ultra-wide-range temperature measurement. Simultaneously, interference caused by power supply fluctuations is eliminated, ensuring the accuracy of temperature measurement, enabling the circuit to provide reliable temperature data in various applications.

Description

Technical Field

[0001] This application relates to the field of power metering technology, and in particular to an NTC high-precision temperature detection circuit. Background Technology

[0002] In vehicle and marine inverter equipment, real-time monitoring of the heat sink surface temperature is a critical step in ensuring the normal operation of the equipment. Currently, most temperature sampling technologies rely on the combination of digital signal processors (DSPs) and temperature sampling circuits, typically using temperature probes fixed to the heat sink surface with screws to sample the temperature.

[0003] In existing technologies, AZ431 and TL431 are commonly used as controllable voltage regulators in temperature sampling circuits to provide a stable power supply. However, the use of external controllable voltage regulators has certain problems. Due to fluctuations in the DSP reference voltage, these external voltage regulators are affected, leading to deviations in the temperature sampling values ​​and reducing the accuracy and stability of temperature sampling. Furthermore, temperature probes typically use negative temperature coefficient (NTC) thermistors as sensors. Although NTC probes have a relatively simple working principle, their output characteristics are non-linear, thus requiring complex linearization processing to achieve accurate measurement over a wide temperature range. However, in practical applications, traditional NTC temperature sampling circuits still have some shortcomings: the error of traditional NTC temperature sampling circuits typically exceeds 1℃, which is clearly insufficient for high-precision measurement requirements. Traditional NTC circuits generally only cover an operating temperature range of around 90℃, failing to meet the monitoring needs of higher or lower temperatures under some special operating conditions. Because traditional circuits are heavily dependent on the power supply, fluctuations in the power supply directly affect the accuracy and stability of the temperature sampling results. Utility Model Content

[0004] This application aims to solve these problems in the prior art by proposing an NTC high-precision temperature detection circuit.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] This application proposes an NTC high-precision temperature detection circuit, including:

[0007] NTC temperature sampling probe, temperature sampling circuit, VCC power supply and DSP;

[0008] The temperature sampling circuit is connected to a reference voltage via a VCC power supply.

[0009] The temperature sampling circuit includes an amplifier and a low-pass filter. The sampling signal from the NTC temperature sampling probe is sent to the DSP after passing through the amplifier and the low-pass filter. The DSP performs temperature detection based on the sampling signal and the reference voltage.

[0010] This application achieves high-precision and ultra-wide-range temperature sampling by employing a bridge arm voltage divider + differential amplification method. Its temperature sampling circuit is connected to the reference voltage through the power supply, which can eliminate the interference caused by power supply fluctuations and ensure the accuracy of temperature sampling.

[0011] Preferably, the temperature sampling circuit further includes: resistor R1, resistor R2 and resistor R3;

[0012] The resistors R1 and R3 are connected in series and then connected in parallel with the VCC power supply.

[0013] The resistor R2 and the NTC temperature sampling probe are connected in series and then connected in parallel with the VCC power supply.

[0014] Preferably, the temperature sampling circuit further includes:

[0015] Select electrical node V1 between resistor R2 and NTC temperature sampling probe, and select electrical node V2 between resistor R1 and resistor R3;

[0016] The electrical node V1 is connected to the non-inverting input of the amplifier via resistor R5;

[0017] The electrical node V2 is connected to the inverting input of the amplifier via resistor R6.

[0018] Preferably, the temperature sampling circuit further includes: a first side circuit;

[0019] One end of the first side circuit is connected to the non-inverting input terminal of the amplifier, and the other end is connected to the output terminal of the amplifier;

[0020] The first side circuit includes a resistor R7 and a capacitor C1.

[0021] Preferably, the temperature sampling circuit further includes: a second side circuit;

[0022] One end of the second side circuit is connected to the inverting input of the amplifier, and the other end is grounded;

[0023] The second side circuit includes a resistor R8 and a capacitor C2.

[0024] Preferably, the low-pass filter further includes:

[0025] Resistor R9 and capacitor C3;

[0026] One end of the resistor R9 is connected to the output terminal of the amplifier, and the other end is connected to the DSP and capacitor C3;

[0027] The other end of capacitor C3 is grounded.

[0028] Preferably, resistor R5 = resistor R6; resistor R7 = resistor R8.

[0029] Preferably, electrical node V1 = VCC power supply * R of NTC temperature sampling probe NTC / (NTC temperature sampling probe R NTC +Resistance R2).

[0030] Electrical node V2 = VCC power supply * resistance R3 / (resistance R1 + resistance R3).

[0031] Preferably, the amplifier output VOUT = (electrical node V2 – electrical node V1) * resistor R8 / resistor R6.

[0032] Compared with the prior art, this application has the following advantages:

[0033] This application describes a high-precision NTC temperature detection circuit that significantly improves the accuracy of the temperature sampling circuit through bridge arm voltage division and differential amplification techniques, reducing the temperature error to as low as 0.3℃, far lower than the error of traditional NTC circuits (typically exceeding 1℃). This enables the circuit to provide more accurate temperature monitoring, meeting the requirements of high-precision temperature sampling. The circuit can cover a wide temperature range from 10℃ to 150℃ and above, overcoming the limitation of traditional NTC circuits operating only within a narrow range, and adapting to more complex operating conditions and a wider range of application scenarios.

[0034] By connecting the temperature sampling circuit to the power supply and reference voltage, this circuit effectively eliminates the interference of power supply fluctuations on the temperature sampling accuracy, ensuring the stability and reliability of temperature monitoring.

[0035] The use of amplifiers and low-pass filters further improves signal quality, reduces noise interference, and enhances the system's anti-interference capability, thereby improving the stability of the temperature sampling signal and ensuring reliability during long-term operation.

[0036] This circuit, through its integrated design, avoids complex linearization processes, improves the system's simplicity and maintainability, reduces the complexity of circuit debugging and maintenance, and lowers the overall system cost. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the NTC high-precision temperature detection circuit in the embodiment.

[0038] Figure 2The circuit diagram for the high-precision NTC temperature detection circuit in this embodiment is shown. Detailed Implementation

[0039] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0040] Reference Figure 1-2 This application proposes an NTC high-precision temperature detection circuit, comprising:

[0041] NTC temperature sampling probe, temperature sampling circuit, VCC power supply and DSP;

[0042] The temperature sampling circuit is connected to the reference voltage via the VCC power supply, ensuring that the system has a stable operating voltage and reference voltage.

[0043] The temperature sampling circuit includes an amplifier and a low-pass filter. The sampling signal from the NTC temperature sampling probe is sent to the DSP after passing through the amplifier and the low-pass filter. The DSP performs temperature detection based on the sampling signal and the reference voltage.

[0044] In this application, the resistance change of the NTC probe is converted into a voltage signal using a bridge arm voltage divider circuit. A differential amplifier enhances the signal strength and removes common-mode noise from the system. The amplifier further amplifies the signal to improve the signal-to-noise ratio, ensuring accurate transmission of the sampled signal. A low-pass filter removes high-frequency noise, making the signal smoother and more stable, facilitating subsequent processing.

[0045] The NTC temperature sampling probe can be a negative temperature coefficient (NTC) thermistor. The NTC probe is mounted on the surface of the inverter's heatsink and can sense real-time temperature changes in the heatsink. The resistance of the NTC probe changes with temperature, thus it can serve as an input source for the temperature signal.

[0046] This application achieves high-precision and ultra-wide-range temperature sampling by employing a bridge arm voltage divider + differential amplification method. Its temperature sampling circuit is connected to the reference voltage through the power supply, which can eliminate the interference caused by power supply fluctuations and ensure the accuracy of temperature sampling.

[0047] In this embodiment, the temperature sampling circuit is used for monitoring the radiator temperature of a vehicle or ship inverter. Inverters generate a large amount of heat during operation; if the radiator temperature is too high, it may damage the equipment. Real-time temperature monitoring using this circuit allows for timely detection of temperature anomalies and the implementation of appropriate protective measures, ensuring the safe and reliable operation of the inverter equipment.

[0048] Preferably, the temperature sampling circuit further includes: resistor R1, resistor R2 and resistor R3;

[0049] The resistors R1 and R3 are connected in series and then in parallel with the VCC power supply; this allows adjustment of the total resistance value of the circuit, thereby affecting the voltage distribution. By appropriately selecting the resistor values, it is possible to ensure that the voltage signal of the NTC temperature probe is within an appropriate range for subsequent temperature sampling and processing.

[0050] The resistor R2 and the NTC temperature sampling probe are connected in series and then in parallel with the VCC power supply to form a voltage divider circuit. The resistance of the NTC temperature probe changes with temperature, therefore the output voltage in the voltage divider circuit also changes with temperature. By reading this changing voltage, the ambient temperature change can be calculated. Specifically, as the temperature of the NTC probe increases, its resistance decreases, resulting in an increase in the output voltage; conversely, as the temperature decreases, the resistance of the NTC probe increases, and the output voltage decreases.

[0051] Preferably, the temperature sampling circuit further includes:

[0052] Select electrical node V1 between resistor R2 and NTC temperature sampling probe, and select electrical node V2 between resistor R1 and resistor R3;

[0053] Electrical node V1 is connected to the non-inverting input of the amplifier via resistor R5. The voltage of electrical node V1 is affected by the temperature change of the NTC probe; when the resistance of the NTC probe changes with temperature, the voltage of V1 also changes. Resistor R5 connects node V1 to the non-inverting input of the amplifier. After the amplifier's non-inverting input is connected to node V1, the amplifier amplifies the voltage signal of node V1. Since the voltage of V1 is controlled by the temperature change of the NTC probe, the signal output by the amplifier reflects this temperature change.

[0054] Electrical node V2 is connected to the inverting input of the amplifier via resistor R6. The voltage at electrical node V2 is affected by the combination of resistors R1 and R3. R1 and R3, through a series voltage divider circuit, distribute the VCC power supply voltage to node V2. Node V2 is connected to the inverting input of the amplifier. The inverting input amplifies the voltage signal at node V2 in reverse. With appropriate gain design, the amplifier can simultaneously process both inverting and non-inverting input signals, achieving differential amplification and thus improving the accuracy of the temperature signal.

[0055] By using differential amplification, the amplifier can better handle the minute voltage fluctuations caused by the resistance changes of the NTC temperature probe and improve the signal strength, making the detection of temperature changes more accurate.

[0056] Preferably, the temperature sampling circuit further includes: a first side circuit;

[0057] One end of the first side circuit is connected to the non-inverting input terminal of the amplifier, and the other end is connected to the output terminal of the amplifier;

[0058] The first side circuit includes a resistor R7 and a capacitor C1.

[0059] The first side circuit acts as a feedback loop, its purpose being to feed the amplifier's output signal back to the input terminal to control the gain and stabilize the circuit. Resistor R7 primarily controls the gain, affecting the amount of signal feedback. Capacitor C1 is used to provide frequency compensation, typically to improve circuit stability, especially under high-frequency signals, preventing oscillations or unstable responses.

[0060] Preferably, the temperature sampling circuit further includes a second side circuit for setting a reference voltage or adjusting the offset of the input signal.

[0061] One end of the second side circuit is connected to the inverting input of the amplifier, and the other end is grounded;

[0062] The second side circuit includes a resistor R8 and a capacitor C2.

[0063] The second side circuit (inverting feedback) is mainly used to control the stability of the inverting input, while capacitor C2 helps reduce high-frequency noise and improve the amplifier's high-frequency response. Resistor R8 affects the current and voltage at the inverting input, controlling signal attenuation or gain. Capacitor C2 is used for high-frequency filtering or further frequency compensation to avoid high-frequency noise or unnecessary oscillations.

[0064] Preferably, the low-pass filter further includes:

[0065] Resistor R9 and capacitor C3;

[0066] One end of the resistor R9 is connected to the output terminal of the amplifier, and the other end is connected to the DSP and capacitor C3;

[0067] The other end of capacitor C3 is grounded.

[0068] Preferably, to maintain circuit symmetry and gain balance, this design helps reduce bias in the circuit and ensures that the signal is processed in a balanced manner in both paths. Further settings are made: resistor R5 = resistor R6; resistor R7 = resistor R8.

[0069] Preferably, V1 is the output voltage of a voltage divider circuit consisting of an NTC (negative temperature coefficient) temperature sampling probe and resistor R2. The resistance of the NTC probe (R...) NTC R changes with temperature. NTC The smaller the value of R, the larger the voltage V1, and vice versa. NTCThe larger the value, the smaller the voltage V1.

[0070] Specifically: Electrical node V1 = VCC power supply * R of NTC temperature sampling probe NTC / (RNTC+ resistor R2 of NTC temperature sampling probe).

[0071] Preferably, the value of V2 is determined by the ratio of resistors R1 and R3. If R3 increases, V2 will increase relative to R1; if R3 decreases, V2 will decrease.

[0072] Specifically: Electrical node V2 = VCC power supply * resistor R3 / (resistor R1 + resistor R3).

[0073] Preferably, the amplifier output VOUT = (electrical node V2 – electrical node V1) * resistor R8 / resistor R6.

[0074] Preferably, in some amplifier circuits, V2 may be a critical voltage node used for reference signals, input signal bias, or gain adjustment.

[0075] In summary, this application, through the combination of bridge arm voltage divider and differential amplification, along with the design of connecting the power supply to the reference voltage, can significantly improve the accuracy and stability of the temperature sampling circuit, thereby achieving high-precision, ultra-wide-range temperature measurement. Simultaneously, this design can eliminate interference caused by power supply fluctuations, ensuring the accuracy of temperature measurement and enabling the circuit to provide reliable temperature data in various applications.

[0076] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. An NTC high-precision temperature detection circuit, characterized in that, include: NTC temperature sampling probe, temperature sampling circuit, VCC power supply and DSP; The temperature sampling circuit is connected to a reference voltage via a VCC power supply. The temperature sampling circuit includes an amplifier and a low-pass filter. The sampling signal from the NTC temperature sampling probe is sent to the DSP after passing through the amplifier and the low-pass filter. The DSP performs temperature detection based on the sampling signal and the reference voltage.

2. The NTC high-precision temperature detection circuit according to claim 1, characterized in that, The temperature sampling circuit further includes: resistor R1, resistor R2 and resistor R3; The resistors R1 and R3 are connected in series and then connected in parallel with the VCC power supply. The resistor R2 and the NTC temperature sampling probe are connected in series and then connected in parallel with the VCC power supply.

3. The NTC high-precision temperature detection circuit according to claim 2, characterized in that, The temperature sampling circuit further includes: Select electrical node V1 between resistor R2 and NTC temperature sampling probe, and select electrical node V2 between resistor R1 and resistor R3; The electrical node V1 is connected to the non-inverting input of the amplifier via resistor R5; The electrical node V2 is connected to the inverting input of the amplifier via resistor R6.

4. The NTC high-precision temperature detection circuit according to claim 3, characterized in that, The temperature sampling circuit further includes: a first side circuit; One end of the first side circuit is connected to the non-inverting input terminal of the amplifier, and the other end is connected to the output terminal of the amplifier; The first side circuit includes a resistor R7 and a capacitor C1.

5. The NTC high-precision temperature detection circuit according to claim 4, characterized in that, The temperature sampling circuit further includes: a second side circuit; One end of the second side circuit is connected to the inverting input of the amplifier, and the other end is grounded; The second side circuit includes a resistor R8 and a capacitor C2.

6. The NTC high-precision temperature detection circuit according to claim 5, characterized in that, The low-pass filter further includes: Resistor R9 and capacitor C3; One end of resistor R9 is connected to the output of the amplifier, and the other end is connected to the DSP and capacitor C3; the other end of capacitor C3 is grounded.

7. The NTC high-precision temperature detection circuit according to claim 6, characterized in that, Also includes: Resistor R5 = Resistor R6; Resistor R7 = Resistor R8.

8. The NTC high-precision temperature detection circuit according to claim 7, characterized in that, Also includes: Electrical node V1 = VCC power supply * R of NTC temperature sampling probe NTC / (NTC temperature sampling probe R NTC +resistance R2); Electrical node V2 = VCC power supply * resistance R3 / (resistance R1 + resistance R3).

9. The NTC high-precision temperature detection circuit according to claim 8, characterized in that, Also includes: The amplifier output VOUT = (electrical node V2 – electrical node V1) * resistor R8 / resistor R6.

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