Current and voltage transmitting device
By using a resistance adjustment module composed of memristors and transistors in the current-voltage transmitter, the problem of mechanical adjustable resistors being susceptible to vibration is solved, achieving high-precision and reliable current-voltage signal conversion and ensuring signal stability and accuracy.
Patent Information
- Application Number
- CN202511700978.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-02-17
AI Technical Summary
In existing current-voltage transmitters, mechanical adjustable resistors are susceptible to mechanical vibration, which can cause resistance changes, signal offset, and errors. Furthermore, existing technologies suffer from high power consumption, low integration, and difficulty in adjustment.
A resistance adjustment module composed of memristors and transistors is used to adjust the resistance of the memristors through digital pulse control, so as to achieve precise adjustment of the zero-point and full-point voltage, replacing the traditional mechanical adjustable resistor and ensuring the stability and accuracy of the signal in the vibrating environment.
It completely eliminates the risk of resistance drift caused by mechanical vibration, achieves higher precision in the reliability of zero-point reference and full-scale output in the current-voltage transmission process, and improves the stability and accuracy of signal conversion.
Smart Images
Figure CN121541737A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of industrial measurement and control technology, and in particular to a current and voltage transmitter. Background Technology
[0002] Current-to-voltage conversion technology can accurately convert current / voltage signals collected by sensors into standardized signals (such as 4-20mA, 0-10V), enabling compatible communication and remote monitoring between devices. In fields such as power, chemical, and intelligent manufacturing, its high-precision conversion directly determines the accuracy of control system decisions, avoiding equipment malfunctions or production accidents caused by signal distortion. It is a key technological support for ensuring the safe and efficient operation of industrial processes.
[0003] Currently, various technical solutions exist for current-to-voltage transmission. These mainly include direct conversion, single op-amp voltage follower, multi-op-amp differential amplification, and I / V transmitter chips. The implementation process of multi-op-amp differential amplification involves: when a 4mA zero-point current signal is input, the output voltage... Since the voltage is not zero, a combination circuit based on OP4 and OP5 is used to achieve zero adjustment so that the transmitter output voltage is zero. OP4 is a voltage follower used to divide the voltage output of the voltage divider network composed of adjustable resistors RP1 and R12. The isolated signal is then transmitted to the inverting input of OP6. Similarly, the output voltage of OP6 is also transmitted to OP5. Therefore, the voltage divider output is changed by adjusting RP1. This will enable the OP6 output voltage The input to the multi-op-amp differential amplifier is a 4mA signal, generating a 0V voltage through differential amplifier OP6, which is then output as the transmitter voltage Uo via inverting proportional amplifier OP7. When the input to the multi-op-amp differential amplifier is a 20mA full-scale signal, different voltage outputs can be achieved by adjusting the full-scale resistor RP2 to meet different measurement and control requirements (i.e., different voltage ranges). Also based on the "virtual open" and "virtual short" characteristics, the output voltage of OP7... Uo The following relationship exists between the in-phase and out-of-phase input voltages: After sorting, we get: At this point, by changing the resistance value of resistor RP2, different full-point transmission voltages (transmission output ranges) can be obtained.
[0004] Adjustable resistors RP1 and RP2 are mostly precision adjustable resistors used for zero-point and full-point adjustment. These resistor packages usually contain mechanical structures, which are not only large and difficult to integrate, but also have poor shock resistance. They are easily affected by mechanical vibration factors, which can cause the output signal to deviate during the current-voltage transmission process and cause errors. Summary of the Invention
[0005] Therefore, it is necessary to provide a current and voltage transmitter to address the aforementioned technical problems.
[0006] This invention provides a current and voltage transmitter, comprising: a power supply module, a zero-point adjustment module, a full-point adjustment module, and a setting device. The input terminal of the power supply module is connected to a +24V external power supply, and the output terminal of the power supply module is connected to the input terminal of the zero-point adjustment module and the input terminal of the full-point adjustment module, respectively. The output terminals of the zero-point adjustment module and the full-point adjustment module are both connected to the setting device. Both the zero-point adjustment module and the full-point adjustment module include a resistance adjustment module. The resistance adjustment module includes: a memristor M1, a first control transistor T1, a second control transistor T2, a third control transistor T3, and a fourth control transistor T4. The collectors of T1 and T2 are connected to the output terminal of the power supply module. The emitter of T1 and the collector of T3 are connected to the positive terminal of M1. The emitter of T2 and the collector of T4 are connected to the reverse terminal of M1. The bases of T1 and T4 are connected to receive the positive pulse control signal CP1. The bases of T2 and T3 are connected to receive the reverse pulse control signal CP2. The zero-point adjustment module includes: resistor R8 and resistance adjustment module. One end of R8 is connected to the output terminal of the reference voltage module, and the other end of R8 is connected in series with the positive terminal of M1 and then grounded. The reference voltage output by the reference voltage module is processed by the zero-point adjustment module and then outputs the zero-point reference voltage to the initial signal conditioning module. The full-point adjustment module includes: resistor R9 and resistance adjustment module. The positive terminals of R9 and M1 are both connected to the inverting input terminal of the secondary signal conditioning module. The output terminal of the secondary signal conditioning module is connected to the inverting terminal of M1. The output voltage of the secondary signal conditioning module is processed by the full-point adjustment module to obtain the transmitted output voltage. Specifically, the resistance value of memristor M1 is controlled by the levels of the positive pulse control signal CP1 and the reverse pulse control signal CP2 in the zero-point adjustment module, thereby changing the zero-point reference voltage of the primary signal conditioning module; the resistance value of memristor M1 is controlled by the levels of the positive pulse control signal CP1 and the reverse pulse control signal CP2 in the full-point adjustment module, thereby adjusting the amplitude of the transmitter output voltage.
[0007] Optionally, the power supply module includes: an input protection diode D1, a first input filter capacitor C1, a second input filter capacitor C2, an integrated adjustable three-port regulator LM317, a first voltage regulating resistor R1, a second voltage regulating resistor R2, and an output filter capacitor C3. The anode of D1 is connected to a +24V external power supply, and the cathode of D1 is connected to the voltage input terminal of LM317, one end of C1, and one end of C2. The output terminals of LM317 are connected to one end of R1 and one end of C3, respectively, and the adjustment terminals of LM317 are connected to the other end of R1 and one end of R2, respectively. The other ends of C1, C2, R2 and C3 are all grounded; The 24V voltage output from the +24V external power supply is processed sequentially by C1, C2, LM317 and C3, and then supplies power to the negative voltage module, the reference voltage module, the zero-point adjustment module and the full-point adjustment module, respectively.
[0008] Optionally, the negative voltage module includes: ICL7660, output filter capacitor C6, first external capacitor C7, and second external capacitor C8; The input terminal of ICL7660 is connected to the output terminal of the power supply module, and the output terminal of ICL7660 is connected to one end of C6, while the other end of C6 is grounded. The CAP+ terminal of ICL7660 is connected to the positive terminal of C8, and the CAP- terminal of ICL7660 is connected to the negative terminal of C8. The low-voltage terminal of ICL7660 is connected to one end of C7, and the other end of C7 is connected to the input terminal of ICL7660. The ground pin of the ICL7660 is grounded.
[0009] Optionally, the reference voltage module includes: an input resistor R3, a precision adjustable reference TL431, a first output filter capacitor C4, and a second output filter capacitor C5; One end of the input resistor R3 is connected to the output terminal of the power supply module, and the other end of the input resistor R3 is connected to the reference terminal and the cathode of the TL431 respectively. The reference terminal of TL431 is also connected to one end of C4 and one end of C5, and the anode of TL431, the other end of C4, and the other end of C5 are all grounded; The cathode and reference electrode of TL431 are connected to form a feedback loop. The voltage output by the power supply module after voltage regulation is input to the cathode of TL431 through R3. The reference voltage output by the reference electrode of TL431 is filtered by C4 and C5 before being output.
[0010] Optionally, it also includes a current sampling module, which includes: a sampling resistor R4 connected in parallel, an output filter capacitor C9, and an output filter capacitor C10; One end of the current sampling module is connected to the current input terminal. The current entering from the current input terminal passes through R4 to generate a sampling voltage, which is then filtered by C9 and C10 and input to the primary signal conditioning module.
[0011] Optionally, the primary signal conditioning module includes: a non-inverting input resistor R6, an inverting input resistor R5, a negative feedback resistor R7, and a first operational amplifier OP1; The sampling voltage output by the current sampling module is input to the non-inverting input terminal of the first operational amplifier OP1 through the non-inverting input resistor R6, and the zero-point reference voltage output by the zero-point adjustment module is input to the inverting input terminal of the first operational amplifier OP1 through R5. The output voltage of the first operational amplifier OP1 is input to the inverting input terminal through the negative feedback resistor R7; The positive power supply of the first operational amplifier OP1 is provided by an external +24V power supply, and the negative power supply of the first operational amplifier OP1 is provided by a negative voltage module.
[0012] Optionally, the secondary signal conditioning module includes: a second operational amplifier OP2 and an output filter capacitor C11; One end of the output filter capacitor C11 is connected to the voltage output terminal of the second operational amplifier OP2; The voltage signal output from the primary signal conditioning module is input to the non-inverting input of the second operational amplifier OP2. The output voltage of the second operational amplifier OP2 is filtered by the output filter capacitor C11 to remove the AC component before being output to the measurement and control equipment. The output voltage of the second operational amplifier OP2 is fed back to the inverting input of the second operational amplifier OP2 through the full-point adjustment module.
[0013] The current and voltage transmitter provided in this embodiment of the invention has the following advantages compared with the prior art: This invention replaces the mechanical adjustable resistor with a memristor as the core. It uses a resistance adjustment module composed of a memristor and four transistors to precisely adjust the resistance of the memristor through a positive pulse control signal CP1 and a negative pulse control signal CP2. In the zero-point adjustment module composed of the resistance adjustment module and resistor R8, changing the memristor resistance will change the zero-point reference voltage. In the full-point adjustment module composed of the resistance adjustment module and resistor R9, changing the memristor resistance will adjust the amplitude of the transmitter output voltage.
[0014] This all-electronic adjustment mechanism completely eliminates the risk of resistance drift caused by mechanical vibration. The digital pulse control method not only achieves higher precision resistance adjustment, but also ensures the reliability of zero-point reference and full-scale output during current-voltage transmission, fundamentally solving the problem of signal offset that traditional mechanical resistors are prone to in industrial vibration environments. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the overall circuit of a current-voltage transmitter provided in one embodiment; Figure 2 A schematic diagram of a power supply module for a current-voltage transmitter provided in one embodiment; Figure 3This is a schematic diagram of a reference voltage module for a current-voltage transmitter provided in one embodiment; Figure 4 This is a schematic diagram of a negative pressure module of a current-voltage transmitter provided in one embodiment; Figure 5 This is a schematic diagram of a current sampling module of a current-voltage transmitter provided in one embodiment; Figure 6 This is a schematic diagram of the primary signal conditioning module of a current-voltage transmitter provided in one embodiment; Figure 7 This is a schematic diagram of a zero-point adjustment module for a current-voltage transmitter provided in one embodiment; Figure 8 This is a schematic diagram of a secondary signal conditioning module of a current-voltage transmitter provided in one embodiment; Figure 9 This is a schematic diagram of a full-point adjustment module for a current-voltage transmitter provided in one embodiment; Figure 10 This is a schematic diagram of a direct conversion of a current-voltage transmitter provided in one embodiment; Figure 11 This is a schematic diagram of a single operational amplifier voltage follower for a current-voltage transmitter provided in one embodiment; Figure 12 This is a schematic diagram of a multi-op-amp differential amplifier for a current-voltage transmitter device provided in one embodiment; Figure 13 This is a schematic diagram of the I / V transmitter chip of a current-voltage transmitter device provided in one embodiment; Figure 14 This is a schematic diagram of the I / V transmitter chip connection of a current and voltage transmitter device provided in one embodiment. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0017] 1. Memristor.
[0018] Some scholars, starting from the completeness of circuits, theoretically predicted the existence of memristors. Memristors are considered the fourth basic circuit element besides resistors, capacitors, and inductors. Their resistance is variable within a certain range and depends on the time-domain integral of the current flowing through it or the applied voltage, and it remains unchanged after power is turned off, thus achieving non-volatile storage of circuit states. Typically, memristors have a threshold voltage; they only exhibit memristor characteristics when the voltage across them exceeds this threshold voltage; otherwise, they are purely resistive devices.
[0019] In addition, memristors have advantages such as low power consumption, simple structure, fast storage speed, high integration density, and compatibility with CMOS technology, and have broad application prospects in fields such as memristor sensors, high-density information storage, intelligent computing, and brain-like artificial intelligence.
[0020] 2. 4-20mA current signal.
[0021] With the development of electronic and sensor technologies, intelligent instruments and meters have been widely used in industrial control environments in recent years. Industrial control environments are typically harsh, often exhibiting various types of electromagnetic interference, including signal crosstalk, grounding interference, and common-mode and differential-mode noise. These interferences become increasingly severe with longer transmission lines. To avoid this interference, noise-insensitive current signals are typically used to represent measured values during signal transmission between instruments and electrical control equipment. Considering explosion-proof requirements, 4mA is generally used to represent zero point, and 20mA to represent full-scale.
[0022] 3. Analog-to-digital converter (ADC).
[0023] Analog-to-digital converters (ADCs) convert continuously changing analog signals (such as voltage and current signals) into discrete digital signals that can be processed by digital devices (such as microcontrollers, PLCs, and industrial control computers) through steps such as sampling, quantization, and encoding. Currently, most applications (sensor measurement, audio signal sampling, and communication systems) use voltage-type ADCs, which sample analog voltage signals and output corresponding digital signals. For current signals, ADC conversion typically requires the current signal to flow through a fixed sampling resistor, converting the current into a voltage signal across the resistor before sending it to the ADC for conversion.
[0024] 4. Operational amplifier.
[0025] An operational amplifier (op-amp) is a high-gain DC-coupled differential voltage amplifier. It performs various functions, including mathematical operations and signal conditioning, through a feedback network. An op-amp has two input terminals (inverting and non-inverting) and one output terminal. The input terminals have extremely high input impedance, while the output terminal has very low output impedance. When the op-amp operates in linear mode, the inverting and non-inverting input terminals can be considered to be at the same potential, i.e., the voltages are equal (virtual short); furthermore, the two input terminals can be considered as open circuits, meaning the current flowing into the inverting and non-inverting input terminals is almost zero (virtual open). Utilizing these properties, voltage signals can be conditioned for specific purposes.
[0026] 5. Existing technology.
[0027] 5.1 Direct conversion.
[0028] like Figure 10 As shown, this scheme is the simplest, directly passing the 4-20mA current signal through a high-precision sampling resistor. Rs One end of the sampling resistor is grounded, and the other end is directly connected to the AD input of the measurement and control equipment (such as a microcontroller). The signal current flows through... Rs At that time, it will be according to Ohm's law. U=IR Generate sampling voltage Vs Then it is used by the measurement and control equipment for AD conversion.
[0029] The technical solution mentioned in section 5.1 is the simplest, but it is only applicable to measurement and control equipment with input isolation, and its scope of application is relatively narrow. Currently, most measurement and control equipment with AD conversion functions does not integrate input isolation circuits. Therefore, if an ADC is directly used to measure the voltage across the sampling resistor, a significant current shunting phenomenon will occur. That is, part of the current signal flows to the ADC device, and part flows through the sampling resistor. This causes the voltage across the sampling resistor to be lower than the actual value, resulting in a significant measurement error.
[0030] 5.2 Single op-amp voltage follower.
[0031] A voltage follower is an application circuit designed using the "virtual short" and "virtual open" operating characteristics of an operational amplifier, meaning that the voltages at the inverting and non-inverting input terminals are assumed to be equal, and the input current is zero. For example... Figure 11 As shown, a 4-20mA current signal passes through a high-precision sampling resistor. Rs One end of the sampling resistor is grounded, and the other end is connected to... R i The non-inverting input of operational amplifier OP1 is connected to the non-inverting input; the inverting input of operational amplifier OP1 is connected to the feedback resistor. R f Connect to the output terminal; R i and R fThese are used to increase input resistance and enhance feedback stability, respectively. The signal current flows through... Rs At that time, a sampling voltage is generated. Vs and after R i The current is fed into the non-inverting input of the operational amplifier; due to the "virtual open" characteristic, it flows through... R i and R f The current is 0, and the voltage at the non-inverting input of the op-amp is... Due to its "virtual shortness" characteristic, and R f The current in the circuit is 0, and the voltage at the inverting input of the op-amp is... Both the output voltage Vo and the output voltage Vo are OP1 enables the output voltage to follow the input voltage.
[0032] The technical solution mentioned in section 5.2 utilizes an operational amplifier to construct a voltage follower, thereby achieving input isolation. However, when a 4-20mA current signal flows through the sampling resistor, its sampling voltage range is also determined by the fixed resistance value of the sampling resistor. Taking a commonly used 100-ohm precision sampling resistor as an example, a 4-20mA current signal will generate a sampling voltage range of 0.4-2V. Typically, the range of the ADC in measurement and control equipment is between 0-3.3V or 0-5V, which obviously cannot fully utilize the effective range of the ADC, resulting in a decrease in measurement accuracy.
[0033] 5.3 Multi-op-amp differential amplification.
[0034] like Figure 12 As shown, in the current detection and amplification unit, regardless of the direction in which the current signal flows through the sampling resistor R9, a voltage will be generated across R9, denoted as . U 1 and U 2. Sampling voltage As a differential amplifier, the OP5 op-amp has a "virtual open circuit" characteristic, meaning there is no current input at the non-inverting and inverting inputs (considered as an "open circuit"). The input voltage at the non-inverting input can be obtained according to the voltage divider law. Based on the "virtual short" characteristic, the voltage at the inverting input of op-amp OP1 is... According to Kirchhoff's circuit laws, the output voltage of the current detection amplifier unit can be obtained. Since R13 = R10, therefore .
[0035] When a 4mA zero-point current signal is input, the output voltage is... Since the voltage is not zero, a combination circuit based on OP4 and OP6 is used to achieve zero adjustment so that the transmitter output voltage is zero. OP4 is a voltage follower used to divide the voltage output of the voltage divider network composed of adjustable resistors RP1 and R12. The isolated signal is then transmitted to the inverting input of OP6. Similarly, the output voltage of OP6 is also transmitted to OP5. Therefore, the voltage divider output is changed by adjusting RP1. This will enable the OP6 output voltage The value is zero (in fact, the OP6 requires a negative power supply to output 0V, and the negative voltage is provided by the ICL7660 switched capacitor voltage converter).
[0036] After the zero-adjustment resistor RP1 is adjusted, a 0V voltage will be generated through the differential amplifier OP6 when a 4mA signal is input, and then finally output as a transmitted voltage through the inverting amplifier OP7. Uo When a 20mA full-scale signal is input, different voltage outputs can be achieved by adjusting the full-scale resistor RP2 to ensure the output voltage meets different measurement and control requirements (i.e., different voltage ranges). Similarly, based on the "virtual open" and "virtual short" characteristics, the OP7 output voltage... Uo The following relationship exists between the in-phase and out-of-phase input voltages: After sorting, we get: It is easy to see that by changing the resistance value of resistor RP2, different full-point transmission voltages (transmission output ranges) can be obtained.
[0037] The technical solution mentioned in section 5.3 effectively addresses the shortcomings of solutions 5.1 and 5.2, achieving both input isolation and adjustable output voltage range, allowing for flexible adjustment based on different ADC devices. However, this solution uses four operational amplifiers and a 78M05 voltage regulator chip for power, resulting in relatively high overall power consumption. Furthermore, the voltage divider network formed by RP1 and R12 directly uses the 5V power supply from the 78M05 as the zero-adjustment reference voltage for the differential amplifier OP3, making it highly susceptible to zero-point drift due to ripple and noise in the 78M05 output voltage. In addition, RP1 and RP2 often employ precision adjustable resistors for zero-point and full-point adjustment. These resistor packages typically contain mechanical structures, making them bulky, difficult to integrate, and with poor shock resistance, easily affected by mechanical vibrations. Adjusting these resistors is also relatively difficult, requiring multiple careful manual adjustments to achieve the desired circuit operation, making large-scale adjustments inconvenient.
[0038] 5.4 I / V transmitter chip.
[0039] For example, the commonly used RCV420 current loop receiver is a highly integrated single-chip solution capable of converting 4-20mA current signals into 0-5V voltage outputs. Figure 13 As shown, according to the chip datasheet, the chip internally consists of a 75Ω sampling resistor, a pre-biased high-precision operational amplifier, and a 10V precision voltage source. Based on the chip's input and output, the transimpedance value of the chip can be calculated to be V. OUT / IIN = 5V / 16mA = 0.3125V / mA; To achieve a 0V output voltage from a 4mA input, the operational amplifier requires voltage biasing, with a bias value of V. OS = (-4mA)(0.3125V / mA) = -1.25V; Operational amplifier voltage gain A D = 5V / (20mA -4mA)(75Ω) = 4.1667V / V. The chip is manufactured according to... Figure 14 By connecting in this way, voltage transmission from 0 to 5V can be achieved.
[0040] The technical solution mentioned in section 5.4 is a single-chip solution, which has high integration and precision, but its output voltage range is fixed, limiting its application scope. Furthermore, the chip is expensive, making it unsuitable for cost-sensitive applications, further restricting its applicability.
[0041] This invention provides a current-voltage transmitter, comprising: a power supply module, a zero-point adjustment module, a full-point adjustment module, and a setting device. The input terminal of the power supply module is connected to a +24V external power supply, and the output terminal of the power supply module is connected to the input terminals of the zero-point adjustment module and the full-point adjustment module, respectively. Both the output terminals of the zero-point adjustment module and the full-point adjustment module are connected to the setting device.
[0042] Both the zero-point adjustment module and the full-point adjustment module include a resistance adjustment module, which comprises: a memristor M1, a first control transistor T1, a second control transistor T2, a third control transistor T3, and a fourth control transistor T4. The collectors of T1 and T2 are connected to the output of the power supply module; the emitter of T1 and the collector of T3 are connected to the positive terminal of M1; and the emitter of T2 and the collector of T4 are connected to the negative terminal of M1. The bases of T1 and T4 are connected to receive the positive pulse control signal CP1, and the bases of T2 and T3 are connected to receive the reverse pulse control signal CP2.
[0043] The zero-point adjustment module includes: resistor R8 and resistance adjustment module. One end of R8 is connected to the output terminal of the reference voltage module, and the other end of R8 is connected in series with the positive terminal of M1 and then grounded. The reference voltage output by the reference voltage module is processed by the zero-point adjustment module and then outputs the zero-point reference voltage to the initial signal conditioning module.
[0044] The full-point adjustment module includes: resistor R9 and a resistance adjustment module. The positive terminals of both R9 and M1 are connected to the inverting input terminal of the secondary signal conditioning module, and the output terminal of the secondary signal conditioning module is connected to the inverting terminal of M1. The output voltage of the secondary signal conditioning module is processed by the full-point adjustment module to obtain the transmitted output voltage.
[0045] Specifically, the resistance value of memristor M1 is controlled by the levels of the forward pulse control signal CP1 and the reverse pulse control signal CP2 in the zero-point adjustment module, thereby changing the zero-point reference voltage of the primary signal conditioning module. The resistance value of memristor M1 is controlled by the levels of the forward pulse control signal CP1 and the reverse pulse control signal CP2 in the full-point adjustment module, thereby adjusting the amplitude of the transmitter output voltage.
[0046] Preferably, the power supply module includes: an input protection diode D1, a first input filter capacitor C1, a second input filter capacitor C2, an integrated adjustable three-port regulator LM317, a first voltage regulating resistor R1, a second voltage regulating resistor R2, and an output filter capacitor C3. The anode of D1 is connected to a +24V external power supply, and the cathode of D1 is connected to the voltage input terminal of LM317, one end of C1, and one end of C2. The output terminal of LM317 is connected to one end of R1 and one end of C3, and the adjustment terminal of LM317 is connected to the other end of R1 and one end of R2. The other ends of C1, C2, R2, and C3 are all grounded. The 24V voltage output from the +24V external power supply is processed sequentially by C1, C2, LM317, and C3, and then supplies power to the negative voltage module, the reference voltage module, the zero-point adjustment module, and the full-point adjustment module, respectively.
[0047] Preferably, the negative voltage module includes: an ICL7660, an output filter capacitor C6, a first external capacitor C7, and a second external capacitor C8. The input terminal (port 8) of the ICL7660 is connected to the output terminal of the power supply module. The output terminal (port 5) of the ICL7660 is connected to one end of C6, and the other end of C6 is grounded. The CAP+ terminal (port 2) of the ICL7660 is connected to the positive terminal of C8, and the CAP- terminal (port 4) of the ICL7660 is connected to the negative terminal of C8. The low-voltage terminal (port 6) of the ICL7660 is connected to one end of C7, and the other end of C7 is connected to the input terminal (port 8) of the ICL7660. The ground pin (port 3) of the ICL7660 is grounded.
[0048] Preferably, the reference voltage module includes: an input resistor R3, a precision adjustable reference TL431, a first output filter capacitor C4, and a second output filter capacitor C5. One end of the input resistor R3 is connected to the output terminal of the power supply module, and the other end of the input resistor R3 is connected to the reference terminal (port 2) and the cathode (port 1) of the TL431, respectively. The reference terminal (port 2) of the TL431 is also connected to one end of C4 and one end of C5. The anode (port 3) of the TL431, the other end of C4, and the other end of C5 are all grounded.
[0049] The cathode (port 1) and reference (port 2) of TL431 are connected to form a feedback loop. The voltage output by the power supply module after voltage regulation is input to the cathode (port 1) of TL431 through R3. The reference voltage output by the reference (port 2) of TL431 is filtered by C4 and C5 before being output.
[0050] Preferably, the system further includes a current sampling module, which comprises a sampling resistor R4 connected in parallel, an output filter capacitor C9, and an output filter capacitor C10. One end of the current sampling module is connected to the current input terminal. The sampling voltage generated by the current entering from the current input terminal after passing through R4 is filtered by C9 and C10 and then input to the primary signal conditioning module.
[0051] Preferably, the primary signal conditioning module includes: a non-inverting input resistor R6, an inverting input resistor R5, a negative feedback resistor R7, and a first operational amplifier OP1; The sampling voltage output from the current sampling module is input to the non-inverting input of the first operational amplifier OP1 via the non-inverting input resistor R6. The zero-point reference voltage output from the zero-point adjustment module is input to the inverting input of the first operational amplifier OP1 via R5. The output voltage of the first operational amplifier OP1 is input to the inverting input via the negative feedback resistor R7.
[0052] The positive power supply of the first operational amplifier OP1 is provided by an external +24V power supply, and the negative power supply of the first operational amplifier OP1 is provided by a negative voltage module.
[0053] Preferably, the secondary signal conditioning module includes a second operational amplifier OP2 and an output filter capacitor C11. One end of the output filter capacitor C11 is connected to the voltage output terminal of the second operational amplifier OP2.
[0054] The voltage signal output from the primary signal conditioning module is input to the non-inverting input of the second operational amplifier OP2. The output voltage of the second operational amplifier OP2 is filtered by the output filter capacitor C11 to remove the AC component before being output to the measurement and control equipment. The output voltage of the second operational amplifier OP2 is fed back to the inverting input of the second operational amplifier OP2 through the full-point adjustment module.
[0055] A specific embodiment of the present invention is provided: 1. Overall design architecture.
[0056] like Figure 1 As shown, the current and voltage transmitter consists of a power supply module, a negative voltage module, a reference voltage module, a primary signal conditioning module, a secondary signal conditioning module, a zero-point adjustment module, a full-point adjustment module, a current sampling module, and a setting device.
[0057] The power supply module is connected to the negative voltage module, reference voltage module, zero-point adjustment module, and full-point adjustment module. The negative voltage module is interconnected with the primary signal conditioning module and the secondary signal conditioning module; the zero-point adjustment module is interconnected with the reference voltage module, the primary signal conditioning module, and the setting device; and the full-point adjustment module is interconnected with the output voltage, the secondary signal conditioning module, and the setting device. The current sampling module is serially connected to a 4-20mA current signal and interconnected with the primary signal conditioning module. A 24V external power supply is interconnected with the power supply module, the primary signal conditioning module, and the secondary signal conditioning module.
[0058] 2. Power supply module.
[0059] The 24V DC power supply commonly used in industrial control environments will damage most of the components in this system. Therefore, the power supply module needs to regulate and stabilize the input voltage before providing the necessary power to other functional modules.
[0060] like Figure 2 As shown, the power supply module consists of an input protection diode D1, input filter capacitors C1 and C2, an LM317 integrated adjustable three-port regulator, regulating resistors R1 and R2, and an output filter capacitor C3. The 24V DC power supply voltage passes sequentially through the anode and cathode of D1, and then through two parallel input filter capacitors C1 and C2 to ground the AC component. One end of C1 and C2 is connected to the cathode of D1 and the voltage input terminal (port 3) of the LM317, while the other end is connected to ground. Subsequently, the filtered AC power supply voltage is input to the input terminal of the LM317. The output terminal (terminal 2) of the LM317 is grounded through a series of regulating resistors R1 and R2. A constant voltage of 1.25V is maintained between the output terminal (port 2) and the adjustment terminal (port 1), and is connected to the series connection of R1 and R2. The adjusted output voltage is approximately 1.25 (1 + R2 / R1) = 8V. Finally, after eliminating the AC component through the output filter capacitor C3 connected between the output terminal of the LM317 and the ground potential, power is supplied to the negative voltage module, the reference voltage module, the zero-point adjustment module, and the full-point adjustment module.
[0061] 3. Reference voltage module.
[0062] The reference voltage module is essentially a constant voltage source, used to provide a precise power supply voltage to the zero-point adjustment module. The zero-point adjustment module then provides a precise differential reference voltage to the primary signal conditioning module based on this voltage, thereby achieving zero-point voltage adjustment.
[0063] like Figure 3As shown, the reference voltage module consists of an input resistor R1, a TL431 precision adjustable reference capacitor, and output filter capacitors C4 and C5. The voltage output from the power supply module, after being regulated, is input to the cathode (port 1) of the TL431 via the input resistor R3. The anode (port 3) is directly connected to ground potential, and the cathode is directly connected to the reference electrode (port 2), allowing the circuit to form a feedback loop for stable operation. The reference voltage output from the reference electrode is filtered by C4 and C5 before being output. C4 and C5 are connected in parallel across the reference terminal and ground potential.
[0064] 4. Negative pressure module.
[0065] In order for the primary and secondary signal conditioning modules to output 0V, a negative voltage lower than 0V needs to be provided to the core component (operational amplifier) of the signal conditioning module. This is the function of the negative voltage module.
[0066] like Figure 4 As shown, the negative voltage module consists of an output filter capacitor C6 and external capacitors C7 and C8. The input terminal (port 8) receives the voltage regulated by the power supply module, and the output terminal (port 5) outputs a voltage with the same amplitude but opposite polarity as the input. The output terminal outputs a reverse voltage after removing AC noise through the output filter capacitor C6 connected to ground. Since the input voltage is greater than 3.5V (8V), the LV terminal (low voltage terminal, port 6) needs to be floating to prevent latch-up. Here, the LV terminal is connected to the input voltage through the external capacitor C7 to achieve this floating. The external capacitor C8 uses a polarized capacitor as a charge pump, with its positive and negative terminals connected to the CAP+ terminal (port 2) and CAP- terminal (port 4), respectively. The ground pin (port 3) is connected to ground, and the other pins (port 1, port 7) are floating.
[0067] 5. Current sampling module.
[0068] In order to convert the current signal into a voltage signal, the current sampling module uses a precision fixed resistor as the sampling resistor and uses Ohm's law to convert the current flowing through the resistor into a voltage drop across the resistor.
[0069] like Figure 5 As shown, the current sampling module consists of a sampling resistor R4 and output filter capacitors C9 and C10. R4, C9, and C10 are connected in parallel, with one end connected to a 4-20mA current signal input and the other end grounded. The sampling voltage generated by the current signal flowing through R4 is filtered by capacitors C9 and C10 and then input to the primary signal conditioning module.
[0070] 6. Primary signal conditioning module.
[0071] The core of the primary signal conditioning module is an operational amplifier operating in differential amplification mode. It receives the sampled voltage from the current sampling module and the zero-point reference voltage from the zero-point adjustment module, and then amplifies the sampled voltage and the zero-point reference voltage by difference (subtraction) before outputting the result with a certain gain. This module mainly enables the transmitter voltage to output 0V even when the sampled voltage corresponding to the zero-point current signal is not zero.
[0072] like Figure 6 As shown, the primary signal conditioning module consists of a non-inverting input resistor R6, an inverting input resistor R5, a negative feedback resistor R7, and an operational amplifier OP1. The sampling voltage (denoted as...) The zero-point reference voltage (denoted as ) is input to the non-inverting input terminal through R6. The input voltage is fed through R5 to the inverting input terminal, and the op-amp output voltage is... The signal is fed to the inverting input terminal via the negative feedback resistor R3. To ensure the primary signal conditioning module outputs 0V, operational amplifier OP1 employs a dual-supply design: the positive supply is provided by a 24V power source, and the negative supply by a negative voltage module. Based on the op-amp's "virtual short" and "virtual open" characteristics, the voltages at the non-inverting and inverting input terminals are the same. Furthermore, based on Kirchhoff's current law at the inverting input terminal, we can obtain... Organized Assume the zero-point current signal generates a sampling voltage. (i.e., Us=U0), according to the above formula, if the transmitter voltage output is made 0V, the zero-point reference voltage... It should be adjusted to , approximately 1.2V.
[0073] 7. Zero point adjustment module.
[0074] The zero-point adjustment module uses a resistive voltage divider network to provide a zero-point reference voltage to the primary signal conditioning module. When adjusting the zero point, a 4mA current signal representing the zero point is first input to the device, and the corresponding output voltage of the device at this time is input to the setting device. The setting device and this device share a common ground (i.e., the ground potentials of both devices are the same, which can be achieved by connecting the grounding terminals of the two devices with a wire). The positive pulse CP1 and reverse pulse CP2 control signals of the zero-point adjustment module are provided by the setting device and sent to the zero-point adjustment module.
[0075] When the setting device detects that the output voltage is higher than 0V, the setting device will keep the CP1 signal line output at a low level and the CP2 output at a high level (5V) pulse, so that the resistance of M1 will continue to increase, raising the zero-point reference voltage, and finally causing the zero-point output voltage of this device to drop to 0V.
[0076] When the setting device detects that the output voltage is lower than 0V, the setting device will output a high-level (5V) pulse on the CP1 signal line and keep CP2 at a low-high level, so that the resistance of M1 will continuously decrease, reducing the zero-point reference voltage, and finally raising the zero-point output voltage of the device to 0V.
[0077] like Figure 7 As shown, the zero-point adjustment module consists of resistor R8, memristor M1, and control transistors T1, T2, T3, and T4. The reference voltage from the reference voltage module is connected to ground via a resistor divider network formed by R1 and M1 in series. The connection between R1 and M1 is a tap of the voltage divider network. The collectors of control transistors T1 and T2 are connected to the regulated output of the power supply module, while the emitters of T3 and T4 are grounded. The emitters of T1 and T3 are connected to the positive terminal of M1, and the emitters of T2 and T4 are connected to the negative terminal of M1. The bases of T1 and T4 are connected and receive the positive pulse control signal CP1, while the bases of T2 and T3 are connected and receive the negative pulse control signal CP2. When CP1 is high and CP2 is low, T1 and T4 are turned on, T2 and T3 are turned off, and the T1-M1-T4 path is established. M1 receives a positive voltage exceeding the memristor threshold, and its resistance decreases. When CP1 is low and CP2 is high, T1 and T4 are off, while T2 and T3 are on, establishing the T2-M1-T3 path. M1 receives a reverse voltage exceeding the memristor threshold, increasing its resistance. When both CP1 and CP2 are low, T1, T4, T2, and T3 are all off, and M1 receives no forward or reverse voltage exceeding the activation threshold, maintaining its resistance. In summary, controlling the levels of CP1 and CP2 adjusts the resistance of memristor M1. The zero-point reference voltage (voltage divider) input to the primary signal conditioning module is... .
[0078] 8. Secondary signal conditioning module.
[0079] The core of the secondary signal conditioning module is an operational amplifier that receives the voltage signal output from the primary signal conditioning module. After adjusting the amplification gain appropriately with the full-point adjustment module, it finally outputs the transmitted voltage. To ensure the secondary signal conditioning module can output 0V, the operational amplifier OP2 employs a dual-power supply design: the positive power supply is provided by a 24V power source, and the negative power supply is provided by a negative voltage module.
[0080] like Figure 8 As shown, the secondary signal conditioning module consists of operational amplifier OP2 and output filter capacitor C11. The voltage signal output from the primary signal conditioning module is input to the non-inverting input of OP2. The output voltage of OP2 is filtered by the output filter capacitor C11 to remove the AC component before being supplied to the measurement and control equipment. One end of C11 is connected to the voltage output terminal of OP2, and the other end is grounded. Simultaneously, the output voltage of OP2 is fed into the inverting input of OP2 through the full-point adjustment module to form negative feedback.
[0081] 9. Full point adjustment module.
[0082] The full-point adjustment module is used to adjust the amplification gain of the operational amplifier in the secondary signal conditioning module, thereby changing the voltage output range of the primary signal conditioning module and ultimately matching the voltage range of the transmitter output with the range of the analog-to-digital converter.
[0083] When adjusting to full point, first input a 20mA current signal indicating full point to the device, and input the corresponding output voltage of the device to the setting device. The setting device and this device share a common ground (i.e., the ground potentials of the two devices are the same, which can be achieved by connecting the grounding terminals of the two devices with a wire). The positive pulse CP1 and reverse pulse CP2 control signals of the full point adjustment module are provided by the setting device and sent to the full point adjustment module.
[0084] When the setting device detects that the full-point voltage is higher than the expected value (this device can convert a 20mA current signal into a voltage value within a certain range, such as 3.3V or 5V, which is the expected value), the setting device will output a high-level (5V) pulse on the CP1 signal line and keep CP2 at a low-high level, so that the resistance of M1 will continuously decrease, eventually reducing the full-point output voltage of this device to the expected value.
[0085] When the setting device detects that the output voltage is lower than the expected value, the setting device will keep the CP1 signal line output at a low level and the CP2 output at a high level (5V) pulse, so that the resistance of M1 will continue to increase, and eventually the full-point output voltage of the device will be raised to the expected value.
[0086] like Figure 9As shown, the full-point adjustment module consists of resistor R9, memristor M1, and control transistors T1, T2, T3, and T4. The output voltage from the secondary signal conditioning module passes through M1 and R9 sequentially before being grounded. The voltage at the connection point of M1 and R9 is supplied to the inverting input of the operational amplifier in the secondary signal conditioning module. The collectors of control transistors T1 and T2 are connected to the regulated output of the power supply module, and the emitters of T3 and T4 are grounded. The emitter of T1 and the collector of T3 are connected to the positive terminal of M1, and the emitter of T2 and the collector of T4 are connected to the inverting terminal of M1. The bases of T1 and T4 are connected and receive the positive pulse control signal CP1, while the bases of T2 and T3 are connected and receive the inverting pulse control signal CP2. When CP1 is high and CP2 is low, T1 and T4 are turned on, and T2 and T3 are turned off, establishing the T1-M1-T4 path. M1 receives a positive voltage exceeding the memristor threshold, and its resistance decreases. When CP1 is low and CP2 is high, T1 and T4 are off, while T2 and T3 are on, establishing the T2-M1-T3 path. M1 receives a reverse voltage exceeding the memristor threshold, increasing its resistance. When both CP1 and CP2 are low, T1, T4, T2, and T3 are all off, and M1 receives no forward or reverse voltage exceeding the activation threshold, resulting in unchanged resistance. Based on this principle, and according to the operational amplifier's "virtual short," the voltage across the M1-R9 tap connected to the inverting input of the secondary signal conditioning module is equal to the output voltage of the primary signal conditioning module. According to the "virtual open circuit" characteristic and Kirchhoff's current law, the M1-R9 tap satisfies After sorting, Therefore, by controlling the levels of CP1 and CP2, the resistance value of memristor M1 can be adjusted, thereby achieving adjustment of the amplitude of the transmitter output voltage.
[0087] 10. Beneficial effects.
[0088] 10.1 Operational Amplifier Usage Scheme. Compared to existing technologies, the number of operational amplifiers used is reduced, achieving the same function with only two operational amplifiers.
[0089] 10.2 The resistance adjustment mechanism in the zero-point adjustment module and the full-point adjustment module is based on the 4T1M (4 transistors and 1 memristor, T1, T2, T3, T4, M1) structure and its resistance adjustment mechanism to realize zero-point and full-point adjustment.
[0090] 10.3 A high-precision constant voltage source is introduced into the voltage divider network in the zero-point adjustment module to provide a stable and accurate zero-point reference voltage for the differential amplifier.
[0091] 10.4 The memristor used is a microelectronic device, and its manufacturing process is well compatible with CMOS technology. It can integrate the zero-point adjustment module, full-point adjustment module, primary signal conditioning module and secondary signal conditioning module into the manufacturing process.
[0092] In summary, this invention features extremely high input impedance and extremely low output impedance, while simultaneously isolating input and output signals, resolving current shunting during current signal sampling, and improving measurement accuracy. By using memristors, it achieves electronic tuning and programmable control of circuit operating parameters, solving the problems of automated calibration, compensation, and adjustment of the device, effectively improving maintenance convenience. Furthermore, the voltage transmitter output of this invention is adjustable within a certain range, allowing adjustments to be made according to the measurement requirements of different measurement and control equipment.
[0093] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.
Claims
1. A current-voltage transmitter, characterized in that, include: The system includes a power supply module, a zero-point adjustment module, a full-point adjustment module, and a setting device. The input terminal of the power supply module is connected to a +24V external power supply. The output terminal of the power supply module is connected to the input terminals of the zero-point adjustment module and the full-point adjustment module, respectively. The output terminals of both the zero-point adjustment module and the full-point adjustment module are connected to the setting device. Both the zero-point adjustment module and the full-point adjustment module include a resistance adjustment module. The resistance adjustment module includes: a memristor M1, a first control transistor T1, a second control transistor T2, a third control transistor T3, and a fourth control transistor T4. The collectors of T1 and T2 are connected to the output terminal of the power supply module. The emitter of T1 and the collector of T3 are connected to the positive terminal of M1. The emitter of T2 and the collector of T4 are connected to the reverse terminal of M1. The bases of T1 and T4 are connected to receive the positive pulse control signal CP1. The bases of T2 and T3 are connected to receive the reverse pulse control signal CP2. The zero-point adjustment module includes: resistor R8 and resistance adjustment module. One end of R8 is connected to the output terminal of the reference voltage module, and the other end of R8 is connected in series with the positive terminal of M1 and then grounded. The reference voltage output by the reference voltage module is processed by the zero-point adjustment module and then outputs the zero-point reference voltage to the initial signal conditioning module. The full-point adjustment module includes: resistor R9 and resistance adjustment module. The positive terminals of R9 and M1 are both connected to the inverting input terminal of the secondary signal conditioning module. The output terminal of the secondary signal conditioning module is connected to the inverting terminal of M1. The output voltage of the secondary signal conditioning module is processed by the full-point adjustment module to obtain the transmitted output voltage. Specifically, the resistance value of memristor M1 is controlled by the levels of the positive pulse control signal CP1 and the reverse pulse control signal CP2 in the zero-point adjustment module, thereby changing the zero-point reference voltage of the primary signal conditioning module; the resistance value of memristor M1 is controlled by the levels of the positive pulse control signal CP1 and the reverse pulse control signal CP2 in the full-point adjustment module, thereby adjusting the amplitude of the transmitter output voltage.
2. The current and voltage transmitter as described in claim 1, characterized in that, The power supply module includes: an input protection diode D1, a first input filter capacitor C1, a second input filter capacitor C2, an integrated adjustable three-port regulator LM317, a first voltage regulating resistor R1, a second voltage regulating resistor R2, and an output filter capacitor C3. The anode of D1 is connected to the +24V external power supply, and the cathode of D1 is connected to the voltage input terminal of LM317, one end of C1, and one end of C2, respectively. The output terminal of the LM317 is connected to one end of R1 and one end of C3, respectively; the adjustment terminal of the LM317 is connected to the other end of R1 and one end of R2, respectively. The other ends of C1, C2, R2, and C3 are all grounded; The 24V voltage output from the +24V external power supply is processed sequentially by C1, C2, LM317 and C3, and then supplies power to the negative voltage module, the reference voltage module, the zero-point adjustment module and the full-point adjustment module, respectively.
3. The current and voltage transmitter as described in claim 2, characterized in that, The negative pressure module includes: ICL7660, output filter capacitor C6, first external capacitor C7 and second external capacitor C8; The input terminal of the ICL7660 is connected to the output terminal of the power supply module, the output terminal of the ICL7660 is connected to one end of C6, and the other end of C6 is grounded. The CAP+ terminal of the ICL7660 is connected to the positive terminal of the C8, and the CAP- terminal of the ICL7660 is connected to the negative terminal of the C8. The low-voltage terminal of the ICL7660 is connected to one end of the C7, and the other end of the C7 is connected to the input terminal of the ICL7660. The ground pin of the ICL7660 is grounded.
4. The current and voltage transmitter as described in claim 1, characterized in that, The reference voltage module includes: an input resistor R3, a precision adjustable reference TL431, a first output filter capacitor C4, and a second output filter capacitor C5; One end of the input resistor R3 is connected to the output terminal of the power supply module, and the other end of the input resistor R3 is connected to the reference terminal and the cathode of the TL431 respectively. The reference electrode of the TL431 is also connected to one end of the C4 and one end of the C5, and the anode of the TL431, the other end of the C4, and the other end of the C5 are all grounded; The cathode and reference electrode of TL431 are connected to form a feedback loop. The voltage output by the power supply module after voltage regulation is input to the cathode of TL431 through R3. The reference voltage output by the reference electrode of TL431 is filtered by C4 and C5 before being output.
5. A current-voltage transmitter as described in claim 1, characterized in that, It also includes a current sampling module, which includes: a sampling resistor R4 connected in parallel, an output filter capacitor C9, and an output filter capacitor C10; One end of the current sampling module is connected to the current input terminal. The sampling voltage generated by the current entering from the current input terminal is filtered by C9 and C10 and then input to the primary signal conditioning module.
6. A current-voltage transmitter as described in any one of claims 3 or 5, characterized in that, The primary signal conditioning module includes: a non-inverting input resistor R6, an inverting input resistor R5, a negative feedback resistor R7, and a first operational amplifier OP1; The sampling voltage output by the current sampling module is input to the non-inverting input terminal of the first operational amplifier OP1 through the non-inverting input resistor R6, and the zero-point reference voltage output by the zero-point adjustment module is input to the inverting input terminal of the first operational amplifier OP1 through R5. The output voltage of the first operational amplifier OP1 is input to the inverting input terminal through the negative feedback resistor R7; The positive power supply of the first operational amplifier OP1 is provided by an external +24V power supply, and the negative power supply of the first operational amplifier OP1 is provided by the negative voltage module.
7. A current-voltage transmitter as described in claim 6, characterized in that, The secondary signal conditioning module includes: a second operational amplifier OP2 and an output filter capacitor C11; One end of the output filter capacitor C11 is connected to the voltage output terminal of the second operational amplifier OP2; The voltage signal output by the primary signal conditioning module is input to the non-inverting input of the second operational amplifier OP2. The output voltage of the second operational amplifier OP2 is filtered by the output filter capacitor C11 to remove the AC component before being output to the measurement and control equipment. The output voltage of the second operational amplifier OP2 is fed back to the inverting input of the second operational amplifier OP2 through the full-point adjustment module.