Temperature detection circuit applied to direct-type electric energy meter terminal seat

Abstract

The invention provides a temperature detection circuit applied to a direct-type electric energy meter terminal seat, and the circuit comprises a triode which is used for sensing the temperature of the direct-type electric energy meter terminal seat; and a temperature measurement chip. And the temperature sensor is used for acquiring a temperature value by utilizing the voltage characteristic that the base-emitter voltage VBE of the triode changes along with the temperature, and outputting temperature data to the MCU of the electric energy meter through the IIC interface. The temperature detection circuit is low in cost, high in precision and simple in circuit design, and only two IO port resources of the MCU need to be occupied.

Description

Technical Field

[0001] The present invention relates to the field of electronics, and in particular to a temperature detection circuit for a terminal seat of a direct meter of an Internet of Things. Background Art

[0002] With the development of the electricity meter industry, to ensure the safe and efficient operation of the power system, temperature detection measures are implemented for direct-type electricity meters. When the temperature exceeds the safe value, the connection between the electricity meter and the user end is promptly disconnected. This prevents the terminal block from overheating when the meter is short-circuited or the load is heavy. In severe cases, it can cause the terminal box and the plastic parts next to the terminal block to overheat and burn, causing irreversible damage to the electricity meter.

[0003] At present, the existing temperature detection mainly uses temperature sensors to determine the real-time temperature of the terminal block. Its measurement accuracy is good, but the price is high. In addition, each copper bar of the terminal block requires a temperature sensor, and each temperature sensor must occupy an IO port. For a three-phase direct meter, 8 IO ports are required, which is a great waste of chip resources. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the existing electric energy meter uses temperature sensor to measure the temperature of the terminal seat, which has many IO ports occupied and chip resources wasted. A temperature detection circuit for the terminal seat of a direct electric energy meter is proposed. The linear relationship between the forward voltage, current and temperature of the transistor is used. When V is known, the temperature of the terminal seat is measured by the temperature sensor. BE , I C In this case, the required temperature T can be obtained.

[0005] The technical solution of the present invention is:

[0006] The present invention provides a temperature detection circuit applied to a direct-type electric energy meter terminal seat, comprising:

[0007] A transistor for sensing the temperature of the terminal seat of the direct-type electric energy meter;

[0008] And temperature measurement chip; used to use the transistor base-emitter voltage V BE The temperature value is obtained based on the voltage characteristics that change with temperature, and the temperature data is output to the energy meter MCU through the IIC interface.

[0009] Furthermore, the temperature measuring chip provides at least two collector currents I to the transistor. C , get the collector current I C The corresponding base-emitter voltage V BE value, and according to V BE Calculate ΔV BE Value; Temperature measuring chip passes ΔV BE The relationship between the value and temperature is used to obtain the real-time temperature value of the terminal block.

[0010] Furthermore, the temperature measurement chip provides two collector currents I to the transistor. C When the temperature measurement chip is configured to provide a first current I to the transistor C1 and the second current I C2 ;

[0011] Get the first current I C1 and the second current I C2 The corresponding base-emitter voltage V BE1 、V BE2 , and calculate V BE1 、V BE2 The difference ΔV BE , the temperature value T is calculated using the following formula;

[0012]

[0013] Where n is the ideality factor, k is the Boltzmann constant, and q is the electron charge, q = 1.6 × 10 -16 C.

[0014] Furthermore, the temperature measurement chip provides m types of collector currents I to the transistor. C When m>2; the temperature measurement chip is configured to provide m types of collectors to the transistor, wherein the second current is N1 times the first current, the third current is N2 times the first current, the mth current is N(m-1) times the first current, and N1≠N2≠…≠N(m-1);

[0015] Obtain the base-emitter voltage corresponding to the collector current, calculate the difference between any two base-emitter voltages, and use the following formula to calculate the corresponding temperature value T;

[0016]

[0017] Among them, i, j∈(1,m), i≠j, V T is the thermovoltage, n is the ideality factor, k is the Boltzmann constant, q is the electron charge, q = 1.6 × 10 -16 C;

[0018] Traverse all base-emitter voltage differences to obtain corresponding temperature values, and take the average value as the real-time temperature value of the terminal block.

[0019] Furthermore, the temperature detection circuit also includes a noise filter for filtering the signal generated by the transistor.

[0020] Furthermore, the noise filter adopts an RCR filter, which is connected between the transistor and the corresponding input terminal of the temperature measurement chip to reduce common mode noise and differential noise.

[0021] Furthermore, the temperature measuring chip obtains the real-time temperature value of the terminal seat and sends it to the electric energy meter MCU through the IIC interface. The electric energy meter MCU determines whether the real-time temperature value exceeds a preset threshold, and disconnects the electric energy meter from the user end if it exceeds the threshold.

[0022] Furthermore, the collector terminal of the transistor is biased to the ground via an internal resistor.

[0023] Beneficial effects of the present invention:

[0024] This invention discloses a temperature detection circuit for a direct-type electric energy meter terminal block. A temperature measurement chip applies different collector currents to a transistor and measures the corresponding base-emitter voltage to obtain a ΔVbe measurement value. This value is then combined with a built-in ΔVbe-temperature relationship model to determine the real-time terminal block temperature. The temperature measurement chip transmits the temperature data to an MCU via an IIC interface, which determines whether the temperature exceeds a safety threshold. If so, it triggers a disconnection between the electric energy meter and the user. This temperature detection circuit offers low cost, high accuracy, and a simple circuit design, requiring only two MCU I / O ports.

[0025] This invention enables real-time monitoring of the meter terminal block temperature and over-temperature protection, improving the safety of the meter. By integrating the temperature measurement chip and the MCU, an automated process for temperature detection, data transmission, threshold determination, and protection action is achieved, enhancing the system's intelligence and reliability.

[0026] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0028] Figure 1 The internal structure diagram of the temperature measurement chip of the present invention is shown.

[0029] Figure 2 The figure shows a principle block diagram of the temperature detection circuit of the present invention. DETAILED DESCRIPTION

[0030] The preferred embodiment of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiment of the present invention is shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0031] The present invention provides a temperature detection circuit for a direct-type electric energy meter terminal block, such as Figure 2 As shown, including:

[0032] A plurality of transistors are provided, the number of which is the same as the terminal block to be measured, and is used to sense the temperature of the terminal block of the direct-type electric energy meter, and the emitter and collector of the transistor are connected to the terminal block;

[0033] And temperature measurement chip; used to use the transistor base-emitter voltage V BE The temperature value is obtained based on the voltage characteristics that change with temperature, and the temperature data is output to the energy meter MCU through the IIC interface;

[0034] The temperature measuring chip provides at least two collector currents I to the transistor. C , get the collector current I C The corresponding base-emitter voltage V BE value, and according to V BE Calculate ΔV BE Value; Temperature measuring chip passes ΔV BE The relationship between the value and temperature is used to obtain the real-time temperature value of the terminal seat;

[0035] The temperature measuring chip sends the real-time temperature value of the terminal block to the electric energy meter MCU through the IIC interface. The electric energy meter MCU determines whether the real-time temperature value exceeds a preset threshold and disconnects the electric energy meter from the user end if it exceeds the threshold.

[0036] In one example, the temperature measurement chip provides two collector currents I to the transistor. C When the temperature measurement chip is configured to provide a first current I to the transistor C1 and the second current I C2 ;

[0037] Get the first current I C1 and the second current I C2 The corresponding base-emitter voltage V BE1 、V BE2 , and calculate V BE1 、V BE2 The difference ΔV BE , the temperature value T is calculated using the following formula;

[0038]

[0039] Where n is the ideality factor, k is the Boltzmann constant, and q is the electron charge, q = 1.6 × 10 -16 C.

[0040] In one example, the temperature measurement chip is configured to provide m types of collectors to the transistor, wherein the second current is N1 times the first current, the third current is N2 times the first current, the mth current is N(m-1) times the first current, and N1≠N2≠…≠N(m-1);

[0041] Obtain the base-emitter voltage corresponding to the collector current, calculate the difference between any two base-emitter voltages, and use the following formula to calculate the corresponding temperature value T;

[0042]

[0043] Among them, i, j∈(1,m), i≠j, V T is the thermovoltage, n is the ideality factor, k is the Boltzmann constant, q is the electron charge, q = 1.6 × 10 -16 C;

[0044] Traverse all base-emitter voltage differences to obtain corresponding temperature values, and take the average value as the real-time temperature value of the terminal block.

[0045] like Figure 1 The figure shows the internal structure of the temperature measuring chip of the present invention. The selected temperature measuring chip provides three kinds of collector working current to the transistor, which can automatically eliminate the resistance in series with the external temperature sensor. By switching the working current of the sensor between the three related currents, different V BE The second current is N1 x I and the third current N2 x I are different multiples of the first current I. The current of the transistor switches between I and N1 x I to obtain ΔV BE1 ; Then between I and N2 xI, we get ΔV BE2 ; The real-time terminal block temperatures are then calculated separately and the average is taken; this method also eliminates the effect of any series resistance on the temperature measurement.

[0046] In this embodiment, to prevent ground noise from interfering with the measurement, the collector terminal of the selected transistor is not referenced to ground, but is biased to ground via an internal resistor of the D- input.

[0047] If the working environment of the temperature measurement circuit is relatively noisy, the noise filter capacitors C2 to C5 cannot completely eliminate the noise. The present invention uses a low-pass RCR filter on the transistor circuit to effectively eliminate the noise, such as Figure 2R3 / C2 / R4 in the circuit is an RCR filter, while R5 / C3 / R6, R7 / C4 / R8, and R9 / C5 / R10 are three other low-pass filters. Resistors R3-R10 can be 100Ω, and C2-C5 can be 1nF. This combination of low-pass filters reduces common common-mode and differential noise. C1 is a filter capacitor for the temperature measurement chip's power port. R1 and R2 are pull-up resistors for the IIC communication interface between the temperature measurement chip and the MCU. Because IIC uses an open-drain output, a pull-up resistor is required on the communication interface. R11 is a pull-up resistor for the overtemperature protection circuit. By default, the THERM output is low. When the detected temperature exceeds the threshold set for the overtemperature protection, the energy meter is disconnected from the user.

[0048] In one example, the temperature detection circuit further includes a noise filter for filtering the signal generated by the transistor; the noise filter adopts an RCR filter, which is connected between the transistor and the corresponding input end of the temperature measurement chip to reduce common mode noise and differential noise.

[0049] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A temperature detection circuit for a direct-type electric energy meter terminal block, characterized in that: include: A transistor for sensing the temperature of the terminal seat of the direct-type electric energy meter; and temperature measurement chips; Used to utilize the transistor base-emitter voltage V BE The temperature value is obtained from the voltage characteristics that change with temperature, and the temperature data is output to the electricity meter MCU through the IIC interface.

2. The temperature detection circuit for a direct-type electric energy meter terminal block according to claim 1, characterized in that: The temperature measuring chip provides at least two collector currents I to the transistor. C , get the collector current I C The corresponding base-emitter voltage V BE value, and according to V BE Calculate ΔV BE Value; Temperature measuring chip passes ΔV BE The relationship between the value and temperature is used to obtain the real-time temperature value of the terminal block.

3. The temperature detection circuit for a direct-type electric energy meter terminal block according to claim 2, characterized in that: The temperature measurement chip provides two collector currents I to the transistor C When the temperature measurement chip is configured to provide a first current I to the transistor C1 and the second current I C2 ; Get the first current I C1 and the second current I C2 The corresponding base-emitter voltage V BE1 、V BE2 , and calculate V BE1 、V BE2 The difference ΔV BE , the temperature value T is calculated using the following formula; Where n is the ideality factor, k is the Boltzmann constant, and q is the electron charge, q = 1.6 × 10 -16 C.

4. The temperature detection circuit for a direct-type electric energy meter terminal block according to claim 2, characterized in that: The temperature measurement chip provides m types of collector current I to the transistor C When m>2; the temperature measurement chip is configured to provide m types of collectors to the transistor, wherein the second current is N1 times the first current, the third current is N2 times the first current, the mth current is N(m-1) times the first current, and N1≠N2≠…≠N(m-1); Obtain the base-emitter voltage corresponding to the collector current, calculate the difference between any two base-emitter voltages, and use the following formula to calculate the corresponding temperature value T; Among them, i, j∈(1,m), i≠j, V T is the thermovoltage, n is the ideality factor, k is the Boltzmann constant, q is the electron charge, q = 1.6 × 10 -16 C; Traverse all base-emitter voltage differences to obtain corresponding temperature values, and take the average value as the real-time temperature value of the terminal block.

5. The temperature detection circuit for a direct-type electric energy meter terminal block according to claim 1, characterized in that: The temperature detection circuit further includes a noise filter for filtering the signal generated by the transistor.

6. The temperature detection circuit for a direct-type electric energy meter terminal block according to claim 5, characterized in that: The noise filter adopts an RCR filter, which is connected between the transistor and the corresponding input terminal of the temperature measurement chip to reduce common mode noise and differential noise.

7. The temperature detection circuit for a direct-type electric energy meter terminal block according to claim 1, characterized in that: The temperature measuring chip obtains the real-time temperature value of the terminal seat and sends it to the electric energy meter MCU through the IIC interface. The electric energy meter MCU determines whether the real-time temperature value exceeds a preset threshold and disconnects the electric energy meter from the user end if it exceeds the threshold.

8. The temperature detection circuit for a direct-type electric energy meter terminal block according to claim 1, characterized in that: The collector terminal of the transistor is biased to ground via an internal resistor.

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