Multi-channel temperature acquisition circuit

Abstract

The utility model provides a multi-channel temperature acquisition circuit. The multi-channel temperature acquisition circuit comprises a plurality of analog input sources, a multiplexer and a micro-control unit, the multiplexer is used for combining a plurality of signals output by the plurality of analog input sources into one channel, and comprises a multiplexer receiving end, a multiplexer output end and a multiplexer selection end; the multiplexer output end of the multiplexer is electrically connected with the voltage follower circuit, the ADC acquisition port and the receiving end of the micro-control unit in sequence; the output end of the micro-control unit, which is used for outputting a selection channel signal, is electrically connected with the selection end of the multiplexer; and the plurality of analog input sources used for generating temperature analog signals are electrically connected with the receiving end of the multiplexer. According to the utility model, multi-channel temperature analog signals are processed by the multiplexer and are transmitted to the same ADC port, so that the purpose of saving micro-control unit resources is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of temperature acquisition circuits, and in particular relates to a multi-channel temperature acquisition circuit. Background Art

[0002] In the use of APF / SVG, grid voltage, grid current, output current, temperature, etc., these signals need to be collected using the ADC port of the MCU; in the use of APF / SVG, temperature collection is a key step to ensure the normal operation of the equipment and prevent damage caused by overheating. The collection and input of temperature data requires multiple ADC ports, which consumes a lot of resources and imposes certain restrictions on the selection of MCU. Utility Model Content

[0003] In view of the above technical problems, the utility model transmits the analog signal of temperature to the same ADC port by building a hardware circuit, thereby achieving the purpose of saving MCU resources.

[0004] The first aspect of the utility model provides a multi-channel temperature acquisition circuit, comprising: a plurality of analog input sources, a multiplexer, and a micro-control unit;

[0005] The multiplexer is used to merge the multiple signals output by the multiple analog input sources into one channel. The multiplexer comprises a multiplexer receiving end, a multiplexer output end, and a multiplexer selection end. The multiplexer output end of the multiplexer is electrically connected to the voltage follower circuit, the ADC acquisition port, and the micro-control unit receiving end in sequence;

[0006] The micro-control unit, the micro-control unit output end for outputting a selection channel signal is electrically connected to the multiplexer selection end;

[0007] The plurality of analog input sources, which are used to generate temperature analog signals, are electrically connected to the receiving end of the multiplexer.

[0008] The beneficial effects of the utility model are as follows: multiple voltage signals are processed by a multiplexer and transmitted to one ADC port, thereby simplifying the CPU processing task; multiple temperature signals are aggregated to one ADC port for processing using the processing signals of the hardware circuit, thereby saving the ADC port resources of the MCU and monitoring the temperature of key components (such as IGBTs, capacitors, etc.) to prevent overheating. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The circuit structure of the new embodiment is shown in FIG. Figure 1 ;

[0010] Figure 2 The circuit structure of the new embodiment is shown in FIG. Figure 2 ;

[0011] Figure 3 The circuit structure of the new embodiment is shown in FIG. Figure 3 ;

[0012] Figure 4 Schematic diagrams of several analog input structures of the new embodiment;

[0013] Figure 5 Circuit diagram of the new embodiment;

[0014] Figure 6 Internal circuit diagram of the low level end of the multiplexing circuit of the new embodiment;

[0015] Figure 7 Schematic diagram of the circuit structure of APF / SVG and multi-channel temperature acquisition circuit in this new embodiment. DETAILED DESCRIPTION

[0016] The following examples further illustrate the content of the utility model, but should not be construed as limiting the utility model. Without departing from the spirit and essence of the utility model, modifications or replacements made to the methods, steps or conditions of the utility model are within the scope of the utility model.

[0017] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0018] In some embodiments of the present invention, Figure 1-7 As shown:

[0019] A multi-channel temperature acquisition circuit includes: a plurality of analog input sources, a multiplexer, and a micro-control unit;

[0020] The multiplexer is used to merge the multiple signals output by the multiple analog input sources into one channel. The multiplexer includes a multiplexer receiving end, a multiplexer output end, and a multiplexer selection end. The multiplexer output end of the multiplexer is electrically connected to the voltage follower circuit, the ADC acquisition port, and the micro-control unit receiving end in sequence;

[0021] The micro-control unit, the micro-control unit output end for outputting a selection channel signal is electrically connected to the multiplexer selection end;

[0022] The plurality of analog input sources, which are used to generate temperature analog signals, are electrically connected to the receiving end of the multiplexer.

[0023] In these embodiments:

[0024] Through voltage, thermistor RT1 and resistor R1 convert temperature parameters into voltage signals, which are transmitted to the multiplexing circuit through the MCU's GPIO1, GPIO2, and GPIO3 signals to select channels, and the collected voltage is output from pin 3 of U6. The MCU's GPIO1, GPIO2, and GPIO3 output high levels (1) and low levels (0) to select the multiplexer channel. For example, when the output of GPIO1, GPIO2, and GPIO3 is 001, channel 1 is selected, that is, the voltage of pin U6-3 is the voltage of pin U6-X1.

[0025] After the voltage is processed by the follower circuit, the collected voltage value is input into the ADC port of the MCU.

[0026] The plurality of analog input sources convert the collected physical temperature into analog signals, which are received by the receiving end of the multiplexer;

[0027] The multiplexer selection end receives the selection signal output by the micro-control unit output end, selects a number of analog signals received by the multiplexer, and outputs them from the multiplexer output end;

[0028] The analog signal output by the multiplexer needs to be voltage followed by a voltage follower circuit, and then converted into a digital signal through an ADC acquisition port, converted into a form readable by the micro-control unit, and input into the receiving end of the micro-control unit for subsequent processing.

[0029] The novel method combines multiple signals into a single transmission channel so as to transmit these signals simultaneously, allowing multiple data streams to be transmitted simultaneously on one physical channel, thereby effectively utilizing limited transmission resources.

[0030] APF (Active Power Filter): APF is a new type of power harmonic control equipment made of modern power electronics technology and digital signal processing technology based on high-speed DSP (digital signal processor) devices. APF can compensate for harmonics with varying magnitude and frequency as well as varying reactive power.

[0031] SVG (Static VAR Generator): SVG, also known as high-voltage dynamic VAR compensation generator or static synchronous compensator, is a device that uses self-commutated power semiconductor bridge converters for dynamic VAR compensation. SVG detects the reactive power required in the system and can quickly generate reactive power of equal magnitude and opposite phase to achieve local reactive balance and maintain real-time high power factor operation of the system.

[0032] The APF is mainly composed of two main parts: the command current operation circuit and the compensation current generation circuit. It monitors the current in the line in real time and converts the analog current signal into a digital signal. After DSP processing, it generates a compensation current with the same amplitude and opposite polarity as the grid harmonic current and injects it into the grid to eliminate harmonics. The APF overcomes the shortcomings of traditional harmonic suppression and reactive power compensation methods such as LC filters, realizes dynamic tracking compensation, and has good governance effects. It can filter out multiple and high-order harmonics at the same time.

[0033] MCU: stands for microcontroller unit, also known as single-chip microcomputer or single-chip microcomputer. MCU appropriately reduces the frequency and specifications of the central processing unit (CPU), and integrates peripheral interfaces such as memory, timer, USB, A / D conversion, UART, PLC, DMA, and even LCD driver circuits on a single chip to form a chip-level computer.

[0034] The following are the optional MCU selections: 8051 series: microcontrollers based on the 8051 core, such as STC89c52, STC89c51. PIC series: a series of microcontrollers for specific applications, with its own unique instruction set and architecture. AVR series: 8-bit microcontrollers characterized by high performance and low power consumption. ARM series: a widely used 32-bit microcontroller series, such as the STM32 series, including cores such as Cortex-M0, Cortex-M3, and Cortex-M4. If the project has strict requirements on power consumption, choose an MCU with low power design. If the project involves sensitive data or security requirements, choose an MCU with security functions, such as the National Technology N32 series.

[0035] Multiplexer: It is an electronic technology widely used in the field of communication and data transmission. Its main function is to transmit multiple input signals through the same transmission line to achieve simultaneous transmission of multiple signals, thereby improving transmission efficiency and bandwidth utilization. The working principle of the multiplexing circuit is mainly based on time division multiplexing, frequency division multiplexing, code division multiplexing and other technologies.

[0036] The multiplexing circuit combines multiple signals into one transmission channel through time division multiplexing, realizes the simultaneous transmission of multiple signals, and improves the transmission efficiency and bandwidth utilization. Maximum allowable current: Make sure that the multiplexer can withstand the current requirements in the project. For critical applications, choose a multiplexer with fault protection and overvoltage protection to improve the reliability of the system.

[0037] In this embodiment, the selection of related components includes: MCU: TMS320F28379DPTP; multiplexer: CD74HC4051M; thermistor: MF52A 153F3950F (A1);

[0038] MCU: TMS320F28379DPTP is designed for advanced closed-loop control applications such as industrial motor drives, photovoltaic inverters and digital power supplies, electric vehicles and transportation, and sensing and signal processing. TMS320F28379DPTP supports the new dual-core C28x architecture, and each core can provide 200MHz signal processing performance. It integrates IEEE 754 single-precision floating-point unit (FPU), trigonometric function accelerator (TMU) and Viterbi / complex math unit (VCU-II).

[0039] Multiplexer: CD74HC4051M is an 8:1 single-channel analog multiplexer with low power consumption, high-speed operation, bidirectional switching and low on-resistance. In a sensor network, it can select specific signals from multiple sensors for collection and processing.

[0040] Thermistor: MF52A 153F3950F (A1), MF52A series thermistors are usually NTC (negative temperature coefficient) thermistors, which have the characteristics of high sensitivity, good stability, fast response, long life and low cost. The thermistor position is integrated inside the IGBT (F3L150R07W2E3_B11) to monitor the operating temperature of the IGBT; the thermistor is placed on the main control board to monitor the ambient temperature of the machine control part.

[0041] IGBT: F3L150R07W2E3_B11, its features include, voltage level: 650V, current level: 150A; uninterruptible power supply (UPS): provides stable power supply for key equipment; solar system solution: realizes efficient power conversion in solar power generation system.

[0042] ADC (Analog to Digital Converter): used to convert continuous analog signals (such as voltage, current, etc.) into discrete digital signals for processing and analysis by digital systems (such as micro-control units, computers, etc.).

[0043] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the analog input source includes: a temperature-sensitive resistor, a voltage-dividing resistor, and an operational amplifier;

[0044] The first end of the temperature-sensitive resistor is electrically connected to the voltage-dividing resistor and the anode of the operational amplifier respectively;

[0045] The cathode of the operational amplifier is electrically connected to the output terminal of the operational amplifier.

[0046] In these embodiments:

[0047] The thermistor is connected to the voltage-dividing resistor. The resistance value of the thermistor changes after the temperature changes. The voltage-dividing resistor is a fixed-value resistor. At this time, the voltage distribution between the thermistor and the voltage-dividing resistor changes. After the voltage at the first end of the thermistor changes, the voltage input to the anode of the operational amplifier changes, thereby reflecting the temperature change at the location of the thermistor.

[0048] The operational amplifier can be connected to negative feedback. Negative feedback is to connect the input and output of the operational amplifier together through a resistor to form a closed loop.

[0049] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the input end of the ADC acquisition port for receiving analog signals is electrically connected to the output end of the voltage follower circuit; the output end of the ADC acquisition port for outputting digital signals is electrically connected to the input end of the micro-control unit.

[0050] In these embodiments:

[0051] Many MCUs have built-in ADC acquisition ports. In MCUs with integrated ADC, data can be directly transmitted to the processor through an internal bus or a dedicated interface. This integration method greatly simplifies circuit design, reduces system costs, and improves the overall performance and reliability of the system.

[0052] The ADC acquisition port can also be set separately. For an external ADC, the data may be transmitted to the MCU through an I / O port or other interfaces (such as SPI, I2C, etc.).

[0053] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the voltage follower circuit includes:

[0054] The output terminal of the multiplexer is electrically connected to the anode of the operational amplifier in the voltage follower circuit;

[0055] The cathode of the operational amplifier in the voltage follower circuit is electrically connected to the output terminal of the operational amplifier in the voltage follower circuit.

[0056] In these embodiments:

[0057] If the amplitude range of the measured signal is too large or contains negative voltage, it is necessary to add an op amp circuit in the front stage of the ADC to adjust the range or increase the offset to adjust the amplitude range of the input ADC and protect the circuit.

[0058] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the voltage follower circuit further includes: a voltage stabilizing and current limiting component, the current limiting component includes a first current limiting diode D1B and a second current limiting diode D1A, and a current limiting voltage dividing resistor R5;

[0059] The cathode of the first current limiting diode is grounded, the anode of the first current limiting diode is electrically connected to the cathode of the second current limiting diode, and the anode of the second current limiting diode is grounded;

[0060] The current-limiting voltage-dividing resistor is electrically connected to the anode of the first current-limiting diode.

[0061] In these embodiments:

[0062] The current-limiting voltage-dividing resistor R5 divides the voltage and limits the current in the voltage path to protect the MCU; the first current-limiting diode D1B and the second current-limiting diode D1A are used to clamp the voltage and protect the ADC port of the MCU. When the voltage or current of the analog signal output by the voltage follower circuit exceeds a certain threshold, the diode will start to conduct, thereby limiting the voltage or current of the signal. When two diodes are connected in series, since they have the same conduction characteristics, they will work together to limit the signal, making the current or voltage limiting effect more significant.

[0063] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that a grounding resistor R6 is also included between the multiplexer output terminal and the anode of the operational amplifier in the voltage follower circuit, and the first end of the grounding resistor R6 is electrically connected to the multiplexer output terminal, and the second end of the grounding resistor is grounded.

[0064] In these embodiments:

[0065] Resistor R6 is a pull-down resistor to prevent initial signal interference. A grounding resistor is connected to the input of the operational amplifier to eliminate zero drift. Selecting an appropriate operational amplifier grounding resistor can make the operational amplifier circuit more stable and the output more accurate. Connecting a grounding resistor to the input of the operational amplifier is mainly to eliminate zero drift, affect input impedance and output stability, and improve the working efficiency and output accuracy of the operational amplifier circuit by properly selecting the resistance value of the grounding resistor, thereby improving the working efficiency and output accuracy of the voltage follower circuit.

[0066] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the receiving end of the multiplexer includes a plurality of analog input receiving ports;

[0067] The multiplexer selection end includes a plurality of selection end receiving ports;

[0068] The multiplexer comprises a ground terminal, a low level input terminal and a low level pin, all of which are grounded.

[0069] In these embodiments:

[0070] The analog input receiving port receives the analog signal generated by the analog input source, and the plurality of selection end receiving ports receive the digital signal output by the output end of the micro-control unit;

[0071] Ground terminal, low level input terminal and low level pin

[0072] The grounding terminal is set as a reference point with zero potential in the circuit, so as to determine the positive and negative potentials and voltage waveforms of various potentials in the circuit. Zero potential protection for personal electrical safety. When leakage occurs in the equipment, grounding can conduct the leakage current to the earth, thereby protecting personnel and equipment from dangers such as electric shock.

[0073] Low level input terminal. In logic circuits, a low level (usually 0V) is considered a valid input signal. When a low level signal is received at the input terminal, the logic circuit such as a logic gate or a trigger will perform the corresponding operation according to its design.

[0074] The ground terminal ensures the safety and stability of the circuit. The low-level input terminal simplifies the design of the logic circuit and filters the external signal. The circuit tends to have a lower loop impedance at a low level than at a higher level, which means that the anti-interference ability is stronger.

[0075] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the multiplexer also includes an energy storage pin, the energy storage pin is connected to the first end of the energy storage capacitor, and the energy storage pin is grounded at the same time; the second end of the energy storage capacitor is grounded.

[0076] In these embodiments:

[0077] The capacitors connected to the multiplexer pins can be selected as 0.1uF, 0.15uF, 0.5uF, etc. Their functions mainly include energy storage, filtering, bypassing and decoupling. These functions together ensure that the multiplexer can receive stable and pure signals and work normally.

[0078] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the micro-control unit output end includes a plurality of micro-control unit output pins for sending channel selection signals to the multiplexer.

[0079] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the plurality of micro-control unit output pins include three GPIO ports.

[0080] In these embodiments:

[0081] GPIO is universal and can be used on different types of hardware platforms without having to modify the underlying circuit. This versatility enables the microcontroller to achieve cross-platform applications.

[0082] In some embodiments of the present invention, Figure 1-7 As shown, the difference from the above embodiment is that the multiplexer further includes a low-level operational amplifier;

[0083] The ground terminal is electrically connected to the cathode of the low-level operational amplifier;

[0084] The low level pin is electrically connected to the anode of the low level operational amplifier;

[0085] The anode of the low-level operational amplifier is electrically connected to the output terminal and the low-level input terminal of the low-level operational amplifier;

[0086] The multiplexer includes a low level input terminal and a low level pin, and the ground terminal is connected.

[0087] In these embodiments:

[0088] When the low level pin E is at a low level, the circuit often has a lower loop impedance than when it is at a higher level, and has a stronger anti-interference ability.

[0089] The temperature parameter is converted into a voltage signal through voltage, thermistor RT1 and resistor R1, and transmitted to the multiplexing circuit through the GPIO1, GPIO2, and GPIO3 signals of the MCU to select the channel. The collected voltage is output from pin 3 of U6, and after being processed by the voltage follower circuit, the collected voltage value is input into the ADC port of the MCU.

[0090] The technical effects of the utility model are multifaceted, merging multiple signals into a single transmission channel so as to transmit the signals simultaneously, allowing multiple data streams to be transmitted simultaneously on a physical channel, thereby effectively utilizing limited transmission resources.

[0091] Although the utility model has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements can be made to the utility model based on the utility model. Therefore, these modifications or improvements made without departing from the spirit of the utility model are within the scope of protection claimed by the utility model.

Claims

1. A multi-channel temperature acquisition circuit, characterized in that: include: A multiplexer, comprising a multiplexer receiving end, a multiplexer output end, and a multiplexer selecting end; A micro-control unit, comprising a micro-control unit receiving end and a micro-control unit output end, wherein the micro-control unit output end for outputting a selection channel signal is electrically connected to the multiplexer selection end; The output end of the multiplexer is electrically connected to the voltage follower circuit, the ADC acquisition port, and the micro-control unit receiving end in sequence; A plurality of analog input sources, which are used to generate temperature analog signals, are electrically connected to the receiving end of the multiplexer.

2. The multi-channel temperature acquisition circuit according to claim 1, characterized in that: The analog input source includes: a temperature-sensitive resistor, a voltage-dividing resistor, and an operational amplifier; The first end of the temperature-sensitive resistor is electrically connected to the voltage-dividing resistor and the anode of the operational amplifier respectively; The cathode of the operational amplifier is electrically connected to the output terminal of the operational amplifier.

3. The multi-channel temperature acquisition circuit according to claim 1, characterized in that: The ADC acquisition port input end for receiving analog signals is electrically connected to the voltage follower circuit output end; the ADC acquisition port output end for outputting digital signals is electrically connected to the micro-control unit input end.

4. The multi-channel temperature acquisition circuit according to claim 1, characterized in that: The voltage follower circuit comprises: The output terminal of the multiplexer is electrically connected to the anode of the operational amplifier in the voltage follower circuit; The cathode of the operational amplifier in the voltage follower circuit is electrically connected to the output terminal of the operational amplifier in the voltage follower circuit.

5. The multi-channel temperature acquisition circuit according to claim 4, characterized in that: The voltage follower circuit further comprises: a voltage stabilizing and current limiting component, wherein the current limiting component comprises a first current limiting diode, a second current limiting diode, and a current limiting voltage dividing resistor; The cathode of the first current limiting diode is grounded, the anode of the first current limiting diode is electrically connected to the cathode of the second current limiting diode, and the anode of the second current limiting diode is grounded; The current-limiting voltage-dividing resistor is electrically connected to the anode of the first current-limiting diode.

6. The multi-channel temperature acquisition circuit according to claim 4, characterized in that: A grounding resistor is also included between the multiplexer output terminal and the anode of the operational amplifier in the voltage follower circuit. A first end of the grounding resistor is electrically connected to the multiplexer output terminal, and a second end of the grounding resistor is grounded.

7. The multi-channel temperature acquisition circuit according to claim 1, characterized in that: The multiplexer receiving end includes a plurality of analog input receiving ports; The multiplexer selection end includes a plurality of selection end receiving ports; The multiplexer comprises a ground terminal, a low level input terminal and a low level pin, all of which are grounded.

8. The multi-channel temperature acquisition circuit according to claim 1, characterized in that: The multiplexer further comprises an energy storage pin, wherein the energy storage pin is connected to a first end of an energy storage capacitor and the energy storage pin is grounded at the same time; and a second end of the energy storage capacitor is grounded.

9. The multi-channel temperature acquisition circuit according to claim 1, characterized in that: The micro-control unit output end includes a plurality of micro-control unit output pins for sending a channel selection signal to the multiplexer, and the plurality of micro-control unit output pins include three GPIO ports.

10. The multi-channel temperature acquisition circuit according to claim 7, characterized in that: The multiplexer also includes a low-level operational amplifier; The ground terminal is electrically connected to the cathode of the low-level operational amplifier; The low level pin is electrically connected to the anode of the low level operational amplifier; The anode of the low-level operational amplifier is electrically connected to the output terminal and the low-level input terminal of the low-level operational amplifier; The multiplexer includes a low level input terminal and a low level pin, and the ground terminal is connected.

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