HPLC (High Performance Liquid Chromatography) medium-voltage carrier high-power signal differential amplification circuit

Abstract

The utility model provides an HPLC (High Performance Liquid Chromatography) medium-voltage carrier high-power signal differential amplification circuit, which relates to the technical field of amplification circuits and comprises a coupling transformer, a bridge sensor, an adjustment analysis module, an AD (Analog to Digital) acquisition circuit and an MCU (Microprogrammed Control Unit) module which are connected in sequence, a common-mode surge suppressor is connected in series between the coupling transformer and the bridge type sensor; the adjustment analysis module at least comprises a digital potentiometer and a differential amplification module, and the control end of the digital potentiometer is connected with the MCU module. According to the utility model, the common-mode surge suppressor is connected in series between the coupling transformer and the bridge type sensor, and the common-mode surge suppressor is formed by connecting the transient voltage suppression diode array and the common-mode choking coil in parallel, so that transient overvoltage active clamping of more than six kilovolts per microsecond is realized, the breakdown risk of a post-stage circuit is reduced, and the reliability of the circuit is improved. The problem that a conventional amplifying circuit is damaged due to power line coupling surge is solved.

Description

Technical Field

[0001] This utility model relates to the field of amplifier circuit technology, and in particular to a differential amplifier circuit for high-power signals with medium-voltage carrier in HPLC. Background Technology

[0002] In high-speed power line carrier systems, high-power signals on medium-voltage lines need to be driven and transmitted through differential amplifier circuits. In complex medium-voltage power environments, common-mode noise is suppressed by differential circuits, and only differential signals are amplified. Through differential amplification, weak differential signals are effectively extracted, common-mode interference is suppressed, and the requirements of HPLC systems, i.e., high-speed power line carrier systems, for high precision and low bit error rate are met.

[0003] A search revealed that utility model patent CN208689397U discloses a signal differential amplifier circuit. The circuit includes a bridge sensor, an adjustment and analysis module, an AD acquisition circuit, and an MCU module. The original signal is converted into two in-phase and out-of-phase input voltage signals containing noise by the corresponding double-arm bridge sensor. The voltage signals are then sent to the adjustment and analysis module. After processing by the adjustment and analysis module, the signals are sent to the AD acquisition circuit, which then sends the signals to the MCU module. The real signal differential amplifier circuit offers precise control, high safety and efficiency, and stable operation.

[0004] The aforementioned disclosure relies solely on the AD623 for common-mode noise suppression, with a typical CMRR of 100dB@1kHz. In industrial environments, such as during motor interference or long-distance transmission, common-mode noise can easily exceed the chip's suppression range. Power line coupling from lightning and switching surges (>6kV / μs) far exceeds the common-mode rejection capability of conventional instrumentation amplifiers, such as the AD623, leading to signal distortion. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a differential amplifier circuit for high-power signals using a medium-pressure carrier wave in HPLC.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a differential amplifier circuit for high-power signals with medium-voltage carrier in HPLC, comprising a coupling transformer, a bridge sensor, an adjustment analysis module, an AD acquisition circuit, and an MCU module connected in sequence; a common-mode surge suppressor is connected in series between the coupling transformer and the bridge sensor; the adjustment analysis module includes at least a digital potentiometer and a differential amplifier module, and the control terminal of the digital potentiometer is connected to the MCU module.

[0007] Preferably, the common-mode surge suppressor is composed of a transient voltage suppression diode array and a common-mode choke connected in parallel.

[0008] Preferably, the clamping voltage of the transient voltage suppression diode array is less than or equal to ±15 volts, and the clamping voltage response time of the transient voltage suppression diode array is less than or equal to one nanosecond.

[0009] Preferably, the impedance of the common-mode choke at a frequency of 500 kHz is greater than or equal to 1,000 ohms, and the saturation current of the common-mode choke at a frequency of 500 kHz is greater than or equal to 5 amperes.

[0010] Preferably, the differential amplification module employs a high-voltage slew rate instrumentation amplifier, wherein the slew rate of the high-voltage slew rate instrumentation amplifier is greater than or equal to 20 volts per microsecond.

[0011] Preferably, the gain adjustment range of the digital potentiometer is from 20 decibels to 60 decibels, and the bandwidth of the digital potentiometer is greater than or equal to one megahertz.

[0012] Preferably, the adjustment analysis module further includes a bandpass filter unit, wherein the passband frequency of the bandpass filter unit is between 3 kHz and 500 kHz.

[0013] Preferably, the stopband attenuation is greater than 40 decibels per decade.

[0014] Preferably, the MCU module is connected to the digital potentiometer via an isolated SPI interface and performs a dynamic gain calibration procedure.

[0015] Preferably, the dynamic gain calibration procedure includes real-time monitoring of the signal-to-noise ratio of the output signal of the AD acquisition circuit.

[0016] Beneficial effects:

[0017] 1. This utility model realizes a common-mode surge suppressor connected in series between the coupling transformer and the bridge sensor. It is composed of a transient voltage suppression diode array and a common-mode choke connected in parallel, which can achieve active clamping of transient overvoltage greater than 6 kV per microsecond, reduce the risk of breakdown of subsequent circuits, and solve the problem of power line coupling surges causing damage to conventional amplifier circuits.

[0018] 2. This utility model realizes a calibration method that uses a microcontroller to dynamically control a digital potentiometer. In a wide temperature range of -40°C to 85°C, the gain drift is compressed to less than ±0.5%. Compared with the mechanical potentiometer, which has a temperature drift degradation of more than 10%, the stability is greatly increased, thus solving the inherent defect of carrier signal amplitude fluctuation.

[0019] 3. This utility model realizes the design of a bandpass filter unit. Through precise passband adaptation from 3 kHz to 500 kHz and stopband attenuation characteristics of more than 40 dB per ten octave, it achieves a suppression capability of more than 60 dB for 50 Hz power frequency noise and a cancellation effect of more than 45 dB for radio frequency interference above 1 MHz. The out-of-band noise suppression rate is greatly improved, and the frequency band mismatch problem of general filters is solved. Attached Figure Description

[0020] Figure 1 This is a flowchart of the present invention.

[0021] Legend:

[0022] 1. Coupling transformer; 2. Bridge sensor; 3. Adjustment and analysis module; 31. Digital potentiometer; 32. Differential amplifier module; 33. Bandpass filter unit; 4. AD acquisition circuit; 5. MCU module; 6. Common mode surge suppressor. Detailed Implementation

[0023] To make the technical means, creative features, and achieved objectives and effects of this utility model easier to understand, the present utility model is further described below with reference to specific embodiments and accompanying drawings. However, the following embodiments are merely preferred embodiments of this utility model and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described in the implementation plan without creative effort are all within the protection scope of this utility model.

[0024] The specific embodiments of this utility model are described below with reference to the accompanying drawings.

[0025] Reference Figure 1 A differential amplifier circuit for high-power signals with medium-voltage carrier in HPLC includes a coupling transformer 1, a bridge sensor 2, an adjustment and analysis module 3, an AD acquisition circuit 4, and an MCU module 5 connected in sequence. A common-mode surge suppressor 6 is connected in series between the coupling transformer 1 and the bridge sensor 2. The adjustment and analysis module 3 includes at least a digital potentiometer 31 and a differential amplifier module 32. The control terminal of the digital potentiometer 31 is connected to the MCU module 5. The common-mode surge suppressor 6 actively clamps power line surge overvoltages greater than 6 kV / µs, reducing the risk of breakdown of subsequent circuits to zero. At the same time, the MCU module 5 dynamically adjusts the digital potentiometer 31 to achieve a gain drift of <±0.5% across the entire temperature range, solving the carrier signal amplitude fluctuation and forming a dual guarantee mechanism of surge protection and gain stability.

[0026] The common-mode surge suppressor 6 is composed of a transient voltage suppression diode array and a common-mode choke connected in parallel. The transient voltage suppression diode array and the common-mode choke connected in parallel form a synergistic protection body. The diode array dissipates the surge energy of large current, and the choke suppresses high-frequency common-mode noise. The two complement each other to improve the transient overvoltage suppression efficiency.

[0027] The clamping voltage of the transient voltage suppressor diode array is less than or equal to ±15 volts, and the clamping voltage response time of the transient voltage suppressor diode array is less than or equal to one nanosecond. The clamping voltage ≤ ±15 volts ensures the safe operation of subsequent sensitive circuits, such as the AD623 chip. The response time ≤ 1 nanosecond can intercept steep surge fronts of 6 kV / microsecond, which greatly improves the response speed compared to conventional protection solutions.

[0028] The impedance of the common-mode choke at a frequency of 500 kHz is greater than or equal to 1,000 ohms, and the saturation current of the common-mode choke at a frequency of 500 kHz is greater than or equal to 5 amps. The impedance ≥ 1,000 ohms at 500 kHz can suppress the common-mode noise at that frequency by > 20 dB, and the saturation current ≥ 5 amps ensures that magnetic saturation does not occur during the transmission of high-power carrier signals, thus avoiding signal distortion.

[0029] The differential amplifier module 32 uses a high-voltage slew rate instrumentation amplifier with a slew rate greater than or equal to 20 volts per microsecond and a slew rate ≥ 20 volts per microsecond. This allows a high-power carrier signal with a peak-to-peak value of 2 volts to be amplified without distortion at a frequency of 500 kHz, with a harmonic distortion rate of <0.1%.

[0030] The gain adjustment range of the digital potentiometer 31 is from 20 dB to 60 dB. The bandwidth of the digital potentiometer 31 is greater than or equal to 1 MHz. The gain range of 20 dB to 60 dB covers the requirements of weak signal amplification and strong signal attenuation in HPLC. The bandwidth ≥ 1 MHz ensures that the group delay of 500 kHz carrier signal amplification is < 10 nanoseconds.

[0031] The adjustment analysis module 3 also includes a bandpass filter unit 33. The passband frequency of the bandpass filter unit 33 is from 3 kHz to 500 kHz. The passband frequency of 3 kHz to 500 kHz is precisely matched to the HPLC carrier frequency band, suppressing 50 Hz power frequency noise by >60 dB and attenuating radio frequency interference above 2 MHz by >45 dB.

[0032] The stopband attenuation of the bandpass filter unit 33 is greater than 40 dB per decade. The characteristic of stopband attenuation > 40 dB / decade causes the noise outside the passband to decrease exponentially. The measured noise suppression at 550 kHz reaches 42 dB, which is a significant improvement over general filters.

[0033] MCU module 5 connects to digital potentiometer 31 via an isolated SPI interface and executes a dynamic gain calibration program. The isolated SPI interface cuts off ground loop interference, and in conjunction with the dynamic gain calibration program, the gain adjustment bit error rate is greatly reduced in the harsh electromagnetic environment of the power field.

[0034] The dynamic gain calibration procedure includes real-time monitoring of the signal-to-noise ratio (SNR) of the output signal of the AD acquisition circuit 4. The real-time SNR is used as feedback, and adjustment is triggered when SNR < 30 dB, so that the carrier signal can maintain a small bit error rate even when the channel attenuation fluctuates.

[0035] The working principle of this utility model is as follows: At the start of production, the medium-voltage power line carrier signal input coupling transformer 1 performs high-voltage isolation and signal coupling. The TVS diode array of the common-mode surge suppressor 6 clamps a surge of >6 kV / µs to ≤±15 V within ≤1 nanosecond. Simultaneously, the common-mode choke suppresses 500 kHz common-mode noise. The bridge sensor 2 converts the coupled signal into a differential voltage signal containing power frequency interference. The digital potentiometer 31 pre-adjusts the signal gain according to the instructions of the MCU module 5, within the range of 20 to 60 dB. The differential signal amplification module 32 amplifies the differential signal with a slew rate of ≥20 volts / microsecond. The bandpass filter unit 33 filters out out-of-band noise from 3 kHz to 500 kHz and has a stopband attenuation of >40 dB / decade. The AD acquisition circuit 4 converts the analog signal into a digital signal with a resolution of ≥16 bits. The MCU module 5 calculates the signal-to-noise ratio (SNR) in real time. When the SNR is <30 dB, the resistance of the digital potentiometer 31 is dynamically adjusted through the isolated SPI interface. The optimized signal is then output to the power line carrier communication system to complete the closed-loop control.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A differential amplifier circuit for high-power signals using a high-voltage carrier wave in HPLC, characterized in that: It includes a coupling transformer (1), a bridge sensor (2), an adjustment and analysis module (3), an AD acquisition circuit (4), and an MCU module (5) connected in sequence; A common-mode surge suppressor (6) is connected in series between the coupling transformer (1) and the bridge sensor (2); The adjustment analysis module (3) includes at least a digital potentiometer (31) and a differential amplifier module (32), and the control terminal of the digital potentiometer (31) is connected to the MCU module (5).

2. The differential amplifier circuit for high-power signals with medium-voltage carrier wave in HPLC according to claim 1, characterized in that: The common-mode surge suppressor (6) is composed of a transient voltage suppression diode array and a common-mode choke connected in parallel.

3. The differential amplifier circuit for high-power signals with medium-voltage carrier wave in HPLC according to claim 2, characterized in that: The clamping voltage of the transient voltage suppression diode array is less than or equal to ±15 volts, and the clamping voltage response time of the transient voltage suppression diode array is less than or equal to one nanosecond.

4. The differential amplifier circuit for high-power signals with medium-voltage carrier in HPLC according to claim 2, characterized in that: The impedance of the common-mode choke at a frequency of 500 kHz is greater than or equal to 1,000 ohms, and the saturation current of the common-mode choke at a frequency of 500 kHz is greater than or equal to 5 amperes.

5. The differential amplifier circuit for high-power signals with medium-voltage carrier in HPLC according to claim 1, characterized in that: The differential amplifier module (32) adopts a high-voltage slew rate instrumentation amplifier, wherein the slew rate of the high-voltage slew rate instrumentation amplifier is greater than or equal to 20 volts per microsecond.

6. The differential amplifier circuit for high-power signals with medium-voltage carrier wave in HPLC according to claim 1, characterized in that: The gain adjustment range of the digital potentiometer (31) is from 20 decibels to 60 decibels, and the bandwidth of the digital potentiometer (31) is greater than or equal to one megahertz.

7. The differential amplifier circuit for high-power signals with medium-voltage carrier wave in HPLC according to claim 1, characterized in that: The adjustment analysis module (3) also includes a bandpass filter unit (33), the passband frequency of which is from 3 kHz to 500 kHz.

8. The differential amplifier circuit for high-power signals with medium-voltage carrier wave in HPLC according to claim 7, characterized in that: The stopband attenuation of the bandpass filter unit (33) is greater than 40 decibels per decade.

9. The differential amplifier circuit for high-power signals with medium-voltage carrier wave in HPLC according to claim 1, characterized in that: The MCU module (5) is connected to the digital potentiometer (31) via an isolated SPI interface and performs a dynamic gain calibration procedure.

10. The differential amplifier circuit for high-power signals with medium-voltage carrier wave in HPLC according to claim 9, characterized in that: The dynamic gain calibration procedure includes real-time monitoring of the signal-to-noise ratio of the output signal of the AD acquisition circuit (4).

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