A high-precision frequency converter data acquisition terminal

Abstract

The utility model discloses a kind of high-precision frequency converter data acquisition terminal, belong to inverter technical field, including main controller, direct current acquisition unit, alternating current acquisition unit, temperature and humidity transmitter, vibration transmitter, wireless communication module and power module, solve under frequency converter high voltage and strong electromagnetic interference environment, realize the technical problem of safety isolation, high-precision, multichannel acquisition to direct current bus and three-phase ac parameter, the utility model realizes the electrical isolation between sampling circuit and control system, effectively improve the safety and anti-common mode interference ability of system, applicable to frequency converter high voltage working environment, direct current bus voltage, current and three-phase ac output voltage, current are multichannel, high-precision acquisition, meet the requirement of precision and real-time of frequency converter operating state monitoring, improve the stability and reliability of sampling signal, reduce the influence of high frequency noise on measurement result.

Description

Technical Field

[0001] This utility model belongs to the field of inverter technology, and in particular relates to a high-precision inverter data acquisition terminal. Background Technology

[0002] Frequency converters are widely used in industrial motor drives, energy conversion, and automation control. Their operation involves various electrical parameters, such as DC bus voltage and current, and three-phase AC output voltage and current. In order to monitor the operating status of frequency converters, diagnose faults, and perform remote operation and maintenance, it is usually necessary to set up a data acquisition terminal to collect the above electrical parameters in real time and transmit the collected data to the upper-level system.

[0003] Existing inverter data acquisition terminals typically acquire voltage and current signals through resistor dividers, current sampling resistors, operational amplifiers, and analog-to-digital converters, with the main controller handling data processing and communication. However, due to the inherent characteristics of inverters, such as high voltage, high-frequency switching, and strong electromagnetic interference, data acquisition circuits face challenges in terms of accuracy, reliability, and safety in practical applications.

[0004] The existing technology has at least the following shortcomings:

[0005] Insufficient isolation between voltage and current sampling and control system: Many data acquisition terminals use non-isolated voltage and current sampling methods, with the sampling circuit directly connected to the main controller and communication module on the same ground. In high-voltage side of the frequency converter or in strong interference environment, common-mode interference is easily introduced, and there may even be breakdown and safety hazards.

[0006] Insufficient multi-channel high-precision synchronous acquisition capability: Existing solutions often sample a single parameter or use multiple low-precision sampling devices to achieve multi-channel acquisition, making it difficult to complete synchronous and high-precision acquisition of DC bus and three-phase AC parameters while ensuring accuracy.

[0007] Poor anti-interference capability and measurement stability: On the output side of the frequency converter, high-frequency pulses, electromagnetic interference and common-mode noise are more serious. Traditional amplification and sampling structures are easily interfered with, resulting in large fluctuations in the acquired signal and accumulation of errors, which affects the long-term stability of the system. Utility Model Content

[0008] The purpose of this invention is to provide a high-precision inverter data acquisition terminal, which solves the technical problem of achieving safe isolation, high-precision, and multi-channel acquisition of DC bus and three-phase AC parameters under high voltage and strong electromagnetic interference environments of inverters.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A high-precision inverter data acquisition terminal includes a main controller, a DC acquisition unit, an AC acquisition unit, a temperature and humidity transmitter, a vibration transmitter, a wireless communication module, and a power supply module. The DC acquisition unit, the AC acquisition unit, the temperature and humidity transmitter, the vibration transmitter, and the wireless communication module are all connected to the main controller.

[0011] The power module supplies power to the main controller, DC acquisition unit, AC acquisition unit, temperature and humidity transmitter, vibration transmitter and wireless communication module;

[0012] The DC acquisition unit is used to acquire the voltage and current signals entering the DC bus of the frequency converter through a DC voltage divider network and a DC current sampling resistor, respectively.

[0013] The AC acquisition unit is used to acquire the A-phase current signal, B-phase current signal and C-phase current signal output by the frequency converter through three AC current sampling resistors respectively;

[0014] The AC acquisition unit is also used to acquire the A-phase voltage signal, B-phase voltage signal and C-phase voltage signal output by the frequency converter through three sets of AC voltage divider resistor networks respectively.

[0015] Preferably, the power supply module includes a 5V output DC-DC module and a three-terminal regulator. The input terminal of the 5V output DC-DC module is connected to the DC bus, and the output terminal outputs 5V power and the first ground wire. The input terminal of the three-terminal regulator is connected to the 5V power supply and the first ground wire, and the output terminal outputs 3.3V power.

[0016] The 5V output DC-DC module is model LM2596S-5.0; the three-terminal regulator is model AMS1117-3.3.

[0017] Preferably, the DC acquisition unit includes a DC voltage divider network, a voltage isolation amplifier, a DC current sampling resistor R13, a current isolation amplifier, and a first AD chip;

[0018] A DC voltage divider network is connected to the input of a voltage isolation amplifier, and the output of the voltage isolation amplifier is connected to one of the AD input channels AIN2 of the first AD chip.

[0019] The two ends of the DC current sampling resistor R13 are differentially connected to the input terminal of the current isolation amplifier, and the output terminal of the current isolation amplifier is connected to the other AD input channel AIN1 of the first AD chip;

[0020] The first AD chip is connected to the main controller via the SPI bus;

[0021] A DC voltage divider network is used to acquire the voltage signal input to the DC bus of the inverter;

[0022] The DC current sampling resistor R13 is used to collect the current signal input to the DC bus of the inverter.

[0023] Preferably, the AC acquisition unit includes an AC voltage sampling unit and an AC current sampling unit;

[0024] The AC voltage sampling unit includes a second AD chip, an A-phase AC voltage signal processing unit, a B-phase AC voltage signal processing unit, and a C-phase AC voltage signal processing unit;

[0025] The A-phase AC voltage signal processing unit includes a protection unit, a current limiting circuit, a voltage divider circuit, an RC anti-aliasing circuit, and an AC voltage amplifier. The input terminals of the A-phase AC voltage signal processing unit are connected to the A-phase and N-phase outputs of the frequency converter, respectively, to acquire the voltage signal VA of the A-phase and the voltage signal VN of the N-phase. The voltage signals VA and VN are respectively input into the protection unit, which is connected to the current limiting circuit. The current limiting circuit is connected to the voltage divider circuit, which is connected to the RC anti-aliasing circuit. The RC anti-aliasing circuit is connected to the input terminal of the AC voltage amplifier. The output terminal of the AC voltage amplifier constitutes the output terminal of the A-phase AC voltage signal processing unit, which is used to output the voltage differential signals of the A-phase, namely the OUT-AP signal and the OUT-AN signal.

[0026] The OUT-AP signal and the OUT-AN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN0 terminal and the AIN1 terminal of the second AD chip;

[0027] The circuit principles of the phase B AC voltage signal processing unit and the phase C AC voltage signal processing unit are the same as those of the phase A AC voltage signal processing unit.

[0028] The input terminals of the B-phase AC voltage signal processing unit are connected to the B-phase and N-phase outputs of the frequency converter, respectively, to collect the voltage signal VB of the B-phase and the voltage signal VN of the N-phase. The output terminals of the B-phase AC voltage signal processing unit output the voltage differential signals of the B-phase, namely the OUT-BP signal and the OUT-BN signal. The OUT-BP signal and the OUT-BN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN2 terminal and the AIN3 terminal of the second AD chip.

[0029] The input terminals of the C-phase AC voltage signal processing unit are connected to the C-phase and N-phase outputs of the frequency converter, respectively, to collect the voltage signal VC of the C-phase and the voltage signal VN of the N-phase. The output terminals of the C-phase AC voltage signal processing unit output the voltage differential signals of the C-phase, namely the OUT-CP signal and the OUT-CN signal. The OUT-CP signal and the OUT-CN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN4 terminal and the AIN5 terminal of the second AD chip.

[0030] The AC current sampling unit includes AC circuit sampling resistor R3, AC circuit sampling resistor R2, AC circuit sampling resistor R1, phase A AC current signal processing unit, phase B AC current signal processing unit, and phase C AC current signal processing unit.

[0031] AC circuit sampling resistors R3, R2, and R1 respectively acquire the A-phase current signal, B-phase current signal, and C-phase current signal.

[0032] The phase A AC current signal processing unit includes a current limiting circuit and an AC current amplifier;

[0033] The input terminal of the phase A AC current signal processing unit is connected to both ends of the sampling resistor R3 to obtain the differential phase A current signal collected by the sampling resistor R3, namely the current signal IA+ and the current signal IA-.

[0034] The current signal IA+ and the current signal IA- are connected to the input terminal of the AC current amplifier through the current limiting circuit. The output terminal of the AC current amplifier constitutes the output terminal of the phase A AC current signal processing unit, which is used to output the phase A current signal OUT-IA. The current signal OUT-IA is input to an AD channel AIN6 of the second AD chip.

[0035] The circuit principles of the phase B AC current signal processing unit and the phase C AC current signal processing unit are the same as those of the phase A AC current signal processing unit.

[0036] The input terminal of the B-phase AC current signal processing unit is connected to both ends of the sampling resistor R2 to obtain the differential B-phase current signal collected by the sampling resistor R2, namely the current signal IB+ and the current signal IB-.

[0037] The output terminal of the B-phase AC current signal processing unit outputs the B-phase current signal OUT-IB, which is input to one AD channel AIN7 of the second AD chip.

[0038] The input terminal of the C-phase AC current signal processing unit is connected to both ends of the sampling resistor R1 to obtain the differential C-phase current signal collected by the sampling resistor R1, namely the current signal IC+ and the current signal IC-.

[0039] The output terminal of the C-phase AC current signal processing unit outputs the C-phase current signal OUT-IC, which is then input to one AD channel AIN8 of the second AD chip.

[0040] The second AD chip is connected to the main controller via the SPI bus.

[0041] Preferably, in the A-phase AC voltage signal processing unit, the protection unit includes a fuse F1 and a TVS diode D1, the current limiting circuit includes a current limiting resistor RLIMIT1, the voltage divider circuit includes resistors R4, R5, R7, R9, R10, R8 and R6, and the RC anti-aliasing circuit includes resistor R11, capacitor C1, resistor R12 and capacitor C2.

[0042] Pin 1 of fuse F1 is connected to the voltage signal VA, and pin 2 is connected to pin 1 of current limiting resistor RLIMIT1; one end of TVS diode D1 is connected to pin 2 of fuse F1, and the other end is connected to the voltage signal VN.

[0043] Pin 2 of the current-limiting resistor RLIMIT1 is connected to pin 1 of resistor R6 via resistors R4, R5, R7, R9 and R10 connected in series. Pin 2 of resistor R6 is connected to the voltage signal VN.

[0044] Pin 1 of resistor R6 is also connected to pin 1 of resistor R11, pin 2 of resistor R11 is connected to pin 1 of resistor R12, and pin 2 of resistor R12 outputs the voltage signal VIN-AP.

[0045] One end of capacitor C1 is connected to pin 2 of resistor R11, and the other end is connected to voltage signal VN. Pin 1 of capacitor C2 is connected to pin 2 of resistor R12, and pin 2 is connected to voltage signal VN.

[0046] The output voltage signal VIN-AN is generated at pin 2 of capacitor C2.

[0047] The AC voltage amplifier includes amplifier IC4, capacitor C7, capacitor C10, capacitor C3, rectifier bridge B1, capacitor C4, capacitor C5, regulator IC1, capacitor C6, regulator IC2, capacitor C8, capacitor C9, regulator IC3, capacitor C11, and capacitor C12.

[0048] The input terminals of rectifier bridge B1 are connected to voltage signal VA and voltage signal VN respectively, and the output terminals output power supply VINA and the first ground line GND1 respectively; capacitor C3 is the filter capacitor at the input terminal of rectifier bridge B1; capacitors C4 and C5 are both filter capacitors at the output terminal of rectifier bridge B1.

[0049] The input terminal of voltage regulator IC1 is connected to power supply VINA and the first ground line GND1, and the output terminal outputs power supply VA1; capacitor C6 is the filter capacitor at the input terminal of voltage regulator IC1.

[0050] The input terminal of voltage regulator IC2 is connected to power supply VA1 and the first ground line GND1, and the output terminal outputs power supply VA2; capacitors C8 and C9 are both filter capacitors at the output terminal of voltage regulator IC2.

[0051] The input terminal of voltage regulator IC3 is connected to power supply VA2 and the first ground line GND1, and the output terminal outputs power supply VH; capacitors C11 and C12 are both filter capacitors at the output terminal of voltage regulator IC3.

[0052] Voltage signals VIN-AP and VIN-AN are input to the IN and GND1 terminals of amplifier IC4, respectively. The VDD1 terminal of amplifier IC4 is connected to the power supply VH, the SHTDN terminal is connected to the first ground GND1, the GND1 terminal is connected to the first ground GND1, the GND2 terminal is connected to the second ground GND2, the OUTN terminal outputs the OUT-AN signal, the OUTP terminal outputs the OUT-AP signal, and the VDD2 terminal is connected to the power supply VCC. Capacitors C7 and C10 are the filter capacitors for the VDD1 and VDD2 terminals of amplifier IC4, respectively.

[0053] The power supply VCC and the second ground GND2 are both provided by the power module.

[0054] Preferably, the DC voltage divider network is a voltage sampling circuit composed of voltage divider resistors; the voltage isolation amplifier is model AMC1311BDWV; the current isolation amplifier is model AMC1301DWV; the first AD chip is model ADS1115; the main controller is model STM32F407VGT6; the temperature and humidity transmitter is model SHT30-DIS; the vibration transmitter is model ADXL345; and the wireless communication module is model ESP32-WROOM-32.

[0055] Preferably, the current limiting circuit is a differential current limiting protection circuit composed of current limiting resistors; the AC current amplifier is model AMC1301DWV; and the second AD chip is model ADS8688.

[0056] The fuse F1 is model 0603L050YR; the TVS diode D1 is model SMBJ18CA; the amplifier IC4 is model AMC1311BDWV; the rectifier bridge B1 is model MB6S; the voltage regulator IC1 is model LM7812; the voltage regulator IC2 is model LM7805; and the voltage regulator IC3 is model AMS1117-3.3.

[0057] This invention relates to a high-precision inverter data acquisition terminal, which solves the technical problem of achieving safe isolation, high-precision, and multi-channel acquisition of DC bus and three-phase AC parameters under high-voltage and strong electromagnetic interference environments. This invention utilizes an isolated voltage and current sampling structure to achieve electrical isolation between the sampling circuit and the control system, effectively improving system safety and common-mode interference immunity. It is suitable for high-voltage inverter operating environments, enabling multi-channel, high-precision acquisition of DC bus voltage and current, as well as three-phase AC output voltage and current, meeting the accuracy and real-time requirements of inverter operation status monitoring. Multi-level protection, current limiting, voltage division, and anti-aliasing processing circuits are introduced into the AC sampling channel to improve the stability and reliability of the sampling signal and reduce the impact of high-frequency noise on the measurement results. Attached Figure Description

[0058] Figure 1 This is a block diagram illustrating the overall principle of this utility model;

[0059] Figure 2 This is a block diagram of the DC acquisition unit of this utility model.

[0060] Figure 3 This is a block diagram of the AC current sampling unit of this utility model;

[0061] Figure 4 This is a block diagram of the AC voltage sampling unit of this utility model.

[0062] Figure 5 This is a circuit diagram of the A-phase AC voltage sampling unit of this utility model. Detailed Implementation

[0063] Depend on Figures 1-5 The high-precision inverter data acquisition terminal shown includes a main controller, a DC acquisition unit, an AC acquisition unit, a temperature and humidity transmitter, a vibration transmitter, a wireless communication module, and a power supply module. The DC acquisition unit, the AC acquisition unit, the temperature and humidity transmitter, the vibration transmitter, and the wireless communication module are all connected to the main controller.

[0064] The power module supplies power to the main controller, DC acquisition unit, AC acquisition unit, temperature and humidity transmitter, vibration transmitter and wireless communication module;

[0065] The power supply module includes a 5V output DC-DC module and a three-terminal regulator. The input terminal of the 5V output DC-DC module is connected to the DC bus, and the output terminal outputs 5V power and the first ground wire. The input terminal of the three-terminal regulator is connected to the 5V power supply and the first ground wire, and the output terminal outputs 3.3V power.

[0066] The 5V output DC-DC module is model LM2596S-5.0; the three-terminal regulator is model AMS1117-3.3.

[0067] The DC acquisition unit is used to acquire the voltage and current signals entering the DC bus of the frequency converter through a DC voltage divider network and a DC current sampling resistor, respectively.

[0068] The DC acquisition unit includes a DC voltage divider network, a voltage isolation amplifier, a DC current sampling resistor R13, a current isolation amplifier, and a first AD chip;

[0069] A DC voltage divider network is connected to the input of a voltage isolation amplifier, and the output of the voltage isolation amplifier is connected to one of the AD input channels AIN2 of the first AD chip.

[0070] The two ends of the DC current sampling resistor R13 are differentially connected to the input terminal of the current isolation amplifier, and the output terminal of the current isolation amplifier is connected to the other AD input channel AIN1 of the first AD chip;

[0071] The first AD chip is connected to the main controller via the SPI bus;

[0072] A DC voltage divider network is used to acquire the voltage signal input to the DC bus of the inverter;

[0073] The DC current sampling resistor R13 is used to collect the current signal input to the DC bus of the inverter.

[0074] The DC voltage divider network is a voltage sampling circuit composed of voltage divider resistors; the voltage isolation amplifier is model AMC1311BDWV; the current isolation amplifier is model AMC1301DWV; the first AD chip is model ADS1115; the main controller is model STM32F407VGT6; the temperature and humidity transmitter is model SHT30-DIS; the vibration transmitter is model ADXL345; and the wireless communication module is model ESP32-WROOM-32.

[0075] The DC acquisition unit proportionally divides the high voltage on the DC bus of the frequency converter using a DC voltage divider network. The divided voltage signal is then input to a voltage isolation amplifier for isolation and amplification, and outputs a low-voltage analog signal proportional to the DC bus voltage. This low-voltage analog signal is then input to the first AD chip for analog-to-digital conversion. Simultaneously, the DC bus current is converted into a proportional small voltage signal through the DC current sampling resistor R13 in the DC bus circuit. This voltage signal is differentially input to a current isolation amplifier, amplified, and outputs a corresponding current detection signal, which is then input to the first AD chip for analog-to-digital conversion. This achieves synchronous sampling of the DC bus voltage and current.

[0076] In this embodiment, voltage isolation amplifiers and current isolation amplifiers are used to isolate the DC bus voltage and current signals, thereby achieving electrical isolation between the high-voltage side and the low-voltage control side and preventing high-voltage interference from being directly coupled to the main controller. At the same time, the isolated and amplified signal has stable amplitude and high linearity, which is beneficial to improving the accuracy and reliability of DC voltage and current sampling and enhancing the system's anti-interference capability in complex electromagnetic environments.

[0077] The AC acquisition unit is used to acquire the A-phase current signal, B-phase current signal and C-phase current signal output by the frequency converter through three AC current sampling resistors respectively;

[0078] The AC acquisition unit is also used to acquire the A-phase voltage signal, B-phase voltage signal and C-phase voltage signal output by the frequency converter through three sets of AC voltage divider resistor networks respectively.

[0079] The AC acquisition unit includes an AC voltage sampling unit and an AC current sampling unit;

[0080] The AC voltage sampling unit includes a second AD chip, an A-phase AC voltage signal processing unit, a B-phase AC voltage signal processing unit, and a C-phase AC voltage signal processing unit;

[0081] The A-phase AC voltage signal processing unit includes a protection unit, a current limiting circuit, a voltage divider circuit, an RC anti-aliasing circuit, and an AC voltage amplifier. The input terminals of the A-phase AC voltage signal processing unit are connected to the A-phase and N-phase outputs of the frequency converter, respectively, to acquire the voltage signal VA of the A-phase and the voltage signal VN of the N-phase. The voltage signals VA and VN are respectively input into the protection unit, which is connected to the current limiting circuit. The current limiting circuit is connected to the voltage divider circuit, which is connected to the RC anti-aliasing circuit. The RC anti-aliasing circuit is connected to the input terminal of the AC voltage amplifier. The output terminal of the AC voltage amplifier constitutes the output terminal of the A-phase AC voltage signal processing unit, which is used to output the voltage differential signals of the A-phase, namely the OUT-AP signal and the OUT-AN signal.

[0082] The OUT-AP signal and the OUT-AN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN0 terminal and the AIN1 terminal of the second AD chip;

[0083] The circuit principles of the phase B AC voltage signal processing unit and the phase C AC voltage signal processing unit are the same as those of the phase A AC voltage signal processing unit.

[0084] The input terminals of the B-phase AC voltage signal processing unit are connected to the B-phase and N-phase outputs of the frequency converter, respectively, to collect the voltage signal VB of the B-phase and the voltage signal VN of the N-phase. The output terminals of the B-phase AC voltage signal processing unit output the voltage differential signals of the B-phase, namely the OUT-BP signal and the OUT-BN signal. The OUT-BP signal and the OUT-BN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN2 terminal and the AIN3 terminal of the second AD chip.

[0085] The input terminals of the C-phase AC voltage signal processing unit are connected to the C-phase and N-phase outputs of the frequency converter, respectively, to collect the voltage signal VC of the C-phase and the voltage signal VN of the N-phase. The output terminals of the C-phase AC voltage signal processing unit output the voltage differential signals of the C-phase, namely the OUT-CP signal and the OUT-CN signal. The OUT-CP signal and the OUT-CN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN4 terminal and the AIN5 terminal of the second AD chip.

[0086] The AC current sampling unit includes AC circuit sampling resistor R3, AC circuit sampling resistor R2, AC circuit sampling resistor R1, phase A AC current signal processing unit, phase B AC current signal processing unit, and phase C AC current signal processing unit.

[0087] AC circuit sampling resistors R3, R2, and R1 respectively acquire the A-phase current signal, B-phase current signal, and C-phase current signal.

[0088] The phase A AC current signal processing unit includes a current limiting circuit and an AC current amplifier;

[0089] The input terminal of the phase A AC current signal processing unit is connected to both ends of the sampling resistor R3 to obtain the differential phase A current signal collected by the sampling resistor R3, namely the current signal IA+ and the current signal IA-.

[0090] The current signal IA+ and the current signal IA- are connected to the input terminal of the AC current amplifier through the current limiting circuit. The output terminal of the AC current amplifier constitutes the output terminal of the phase A AC current signal processing unit, which is used to output the phase A current signal OUT-IA. The current signal OUT-IA is input to an AD channel AIN6 of the second AD chip.

[0091] In the A-phase AC voltage signal processing unit, the protection unit includes fuse F1 and TVS tube D1, the current limiting circuit includes current limiting resistor RLIMIT1, the voltage divider circuit includes resistors R4, R5, R7, R9, R10, R8 and R6, and the RC anti-aliasing circuit includes resistor R11, capacitor C1, resistor R12 and capacitor C2.

[0092] Pin 1 of fuse F1 is connected to the voltage signal VA, and pin 2 is connected to pin 1 of current limiting resistor RLIMIT1; one end of TVS diode D1 is connected to pin 2 of fuse F1, and the other end is connected to the voltage signal VN.

[0093] Pin 2 of the current-limiting resistor RLIMIT1 is connected to pin 1 of resistor R6 via resistors R4, R5, R7, R9 and R10 connected in series. Pin 2 of resistor R6 is connected to the voltage signal VN.

[0094] Pin 1 of resistor R6 is also connected to pin 1 of resistor R11, pin 2 of resistor R11 is connected to pin 1 of resistor R12, and pin 2 of resistor R12 outputs the voltage signal VIN-AP.

[0095] One end of capacitor C1 is connected to pin 2 of resistor R11, and the other end is connected to voltage signal VN. Pin 1 of capacitor C2 is connected to pin 2 of resistor R12, and pin 2 is connected to voltage signal VN.

[0096] The output voltage signal VIN-AN is generated at pin 2 of capacitor C2.

[0097] The AC voltage amplifier includes amplifier IC4, capacitor C7, capacitor C10, capacitor C3, rectifier bridge B1, capacitor C4, capacitor C5, regulator IC1, capacitor C6, regulator IC2, capacitor C8, capacitor C9, regulator IC3, capacitor C11, and capacitor C12.

[0098] The input terminals of rectifier bridge B1 are connected to voltage signal VA and voltage signal VN respectively, and the output terminals output power supply VINA and the first ground line GND1 respectively; capacitor C3 is the filter capacitor at the input terminal of rectifier bridge B1; capacitors C4 and C5 are both filter capacitors at the output terminal of rectifier bridge B1.

[0099] The input terminal of voltage regulator IC1 is connected to power supply VINA and the first ground line GND1, and the output terminal outputs power supply VA1; capacitor C6 is the filter capacitor at the input terminal of voltage regulator IC1.

[0100] The input terminal of voltage regulator IC2 is connected to power supply VA1 and the first ground line GND1, and the output terminal outputs power supply VA2; capacitors C8 and C9 are both filter capacitors at the output terminal of voltage regulator IC2.

[0101] The input terminal of voltage regulator IC3 is connected to power supply VA2 and the first ground line GND1, and the output terminal outputs power supply VH; capacitors C11 and C12 are both filter capacitors at the output terminal of voltage regulator IC3.

[0102] Voltage signals VIN-AP and VIN-AN are input to the IN and GND1 terminals of amplifier IC4, respectively. The VDD1 terminal of amplifier IC4 is connected to the power supply VH, the SHTDN terminal is connected to the first ground GND1, the GND1 terminal is connected to the first ground GND1, the GND2 terminal is connected to the second ground GND2, the OUTN terminal outputs the OUT-AN signal, the OUTP terminal outputs the OUT-AP signal, and the VDD2 terminal is connected to the power supply VCC. Capacitors C7 and C10 are the filter capacitors for the VDD1 and VDD2 terminals of amplifier IC4, respectively.

[0103] The power supply VCC and the second ground GND2 are both provided by the power module.

[0104] The phase A AC current signal processing unit converts the phase A AC current into a proportionally small differential voltage signal through the AC current sampling resistor R3 set in the phase A output circuit. The differential voltage signal is then input to the AC current amplifier after passing through a differential current limiting protection circuit composed of current limiting resistors. The AC current amplifier isolates and amplifies the differential voltage signal and outputs a single-ended analog signal OUT-IA proportional to the amplitude of the phase A AC current. The single-ended analog signal is input to the second AD chip for analog-to-digital conversion, thereby realizing accurate sampling of the phase A AC current.

[0105] The circuit principles of the phase B AC current signal processing unit and the phase C AC current signal processing unit are the same as those of the phase A AC current signal processing unit.

[0106] The input terminal of the B-phase AC current signal processing unit is connected to both ends of the sampling resistor R2 to obtain the differential B-phase current signal collected by the sampling resistor R2, namely the current signal IB+ and the current signal IB-.

[0107] The output terminal of the B-phase AC current signal processing unit outputs the B-phase current signal OUT-IB, which is input to one AD channel AIN7 of the second AD chip.

[0108] The input terminal of the C-phase AC current signal processing unit is connected to both ends of the sampling resistor R1 to obtain the differential C-phase current signal collected by the sampling resistor R1, namely the current signal IC+ and the current signal IC-.

[0109] The output terminal of the C-phase AC current signal processing unit outputs the C-phase current signal OUT-IC, which is then input to one AD channel AIN8 of the second AD chip.

[0110] The second AD chip is connected to the main controller via the SPI bus.

[0111] The current limiting circuit is a differential current limiting protection circuit composed of current limiting resistors; the AC current amplifier is model AMC1301DWV; the second AD chip is model ADS8688.

[0112] The fuse F1 is model 0603L050YR; the TVS diode D1 is model SMBJ18CA; the amplifier IC4 is model AMC1311BDWV; the rectifier bridge B1 is model MB6S; the voltage regulator IC1 is model LM7812; the voltage regulator IC2 is model LM7805; and the voltage regulator IC3 is model AMS1117-3.3.

[0113] In this embodiment, by independently sampling the three-phase AC voltage and three-phase AC current, and employing a combination of isolation amplification and differential sampling, the common-mode interference immunity and measurement accuracy of the AC sampling signals are effectively improved. Simultaneously, by synchronously acquiring the voltage and current signals of each phase using a multi-channel AD chip, real-time monitoring and accurate analysis of the inverter's output status are achieved, thereby enhancing the safety and reliability of the system operation.

[0114] In this embodiment, by setting independent rectifier bridges and power supply circuits for the AC voltage signal processing units of phases A, B, and C respectively, the voltage signal processing units of each phase are independent of each other at the power supply level, avoiding mutual interference introduced by power supply coupling between different phases. At the same time, this structure can reduce the impact of three-phase voltage imbalance on sampling accuracy, improve the independence and consistency of AC voltage sampling of each phase, and thus further improve the accuracy of three-phase voltage measurement and the overall stability of the system.

[0115] This invention relates to a high-precision inverter data acquisition terminal, which solves the technical problem of achieving safe isolation, high-precision, and multi-channel acquisition of DC bus and three-phase AC parameters under high-voltage and strong electromagnetic interference environments. This invention utilizes an isolated voltage and current sampling structure to achieve electrical isolation between the sampling circuit and the control system, effectively improving system safety and common-mode interference immunity. It is suitable for high-voltage inverter operating environments, enabling multi-channel, high-precision acquisition of DC bus voltage and current, as well as three-phase AC output voltage and current, meeting the accuracy and real-time requirements of inverter operation status monitoring. The AC sampling channel incorporates multi-level protection, current limiting, voltage division, and anti-aliasing circuits to improve the stability and reliability of the sampling signal and reduce the impact of high-frequency noise on the measurement results.

Claims

1. A high-precision frequency converter data acquisition terminal, characterized in that: It includes a main controller, a DC acquisition unit, an AC acquisition unit, a temperature and humidity transmitter, a vibration transmitter, a wireless communication module, and a power supply module. The DC acquisition unit, the AC acquisition unit, the temperature and humidity transmitter, the vibration transmitter, and the wireless communication module are all connected to the main controller. The power module supplies power to the main controller, DC acquisition unit, AC acquisition unit, temperature and humidity transmitter, vibration transmitter and wireless communication module; The DC acquisition unit is used to acquire the voltage and current signals entering the DC bus of the frequency converter through a DC voltage divider network and a DC current sampling resistor, respectively. The AC acquisition unit is used to acquire the A-phase current signal, B-phase current signal and C-phase current signal output by the frequency converter through three AC current sampling resistors respectively; The AC acquisition unit is also used to acquire the A-phase voltage signal, B-phase voltage signal and C-phase voltage signal output by the frequency converter through three sets of AC voltage divider resistor networks respectively.

2. The high-precision inverter data acquisition terminal as described in claim 1, characterized in that: The power supply module includes a 5V output DC-DC module and a three-terminal regulator. The input terminal of the 5V output DC-DC module is connected to the DC bus, and the output terminal outputs 5V power and the first ground wire. The input terminal of the three-terminal regulator is connected to the 5V power supply and the first ground wire, and the output terminal outputs 3.3V power. The 5V output DC-DC module is model LM2596S-5.0; the three-terminal regulator is model AMS1117-3.

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3. The high-precision frequency converter data acquisition terminal as described in claim 2, characterized in that: The DC acquisition unit includes a DC voltage divider network, a voltage isolation amplifier, a DC current sampling resistor R13, a current isolation amplifier, and a first AD chip; A DC voltage divider network is connected to the input of a voltage isolation amplifier, and the output of the voltage isolation amplifier is connected to one of the AD input channels AIN2 of the first AD chip. The two ends of the DC current sampling resistor R13 are differentially connected to the input terminal of the current isolation amplifier, and the output terminal of the current isolation amplifier is connected to the other AD input channel AIN1 of the first AD chip; The first AD chip is connected to the main controller via the SPI bus; A DC voltage divider network is used to acquire the voltage signal input to the DC bus of the inverter; The DC current sampling resistor R13 is used to collect the current signal input to the DC bus of the inverter.

4. The high-precision frequency converter data acquisition terminal as described in claim 2, characterized in that: The AC acquisition unit includes an AC voltage sampling unit and an AC current sampling unit; The AC voltage sampling unit includes a second AD chip, an A-phase AC voltage signal processing unit, a B-phase AC voltage signal processing unit, and a C-phase AC voltage signal processing unit; The A-phase AC voltage signal processing unit includes a protection unit, a current limiting circuit, a voltage divider circuit, an RC anti-aliasing circuit, and an AC voltage amplifier. The input terminals of the A-phase AC voltage signal processing unit are connected to the A-phase and N-phase outputs of the frequency converter, respectively, to acquire the voltage signal VA of the A-phase and the voltage signal VN of the N-phase. The voltage signals VA and VN are respectively input into the protection unit, which is connected to the current limiting circuit. The current limiting circuit is connected to the voltage divider circuit, which is connected to the RC anti-aliasing circuit. The RC anti-aliasing circuit is connected to the input terminal of the AC voltage amplifier. The output terminal of the AC voltage amplifier constitutes the output terminal of the A-phase AC voltage signal processing unit, which is used to output the voltage differential signals of the A-phase, namely the OUT-AP signal and the OUT-AN signal. The OUT-AP signal and the OUT-AN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN0 terminal and the AIN1 terminal of the second AD chip; The circuit principles of the phase B AC voltage signal processing unit and the phase C AC voltage signal processing unit are the same as those of the phase A AC voltage signal processing unit. The input terminals of the B-phase AC voltage signal processing unit are connected to the B-phase and N-phase outputs of the frequency converter, respectively, to collect the voltage signal VB of the B-phase and the voltage signal VN of the N-phase. The output terminals of the B-phase AC voltage signal processing unit output the voltage differential signals of the B-phase, namely the OUT-BP signal and the OUT-BN signal. The OUT-BP signal and the OUT-BN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN2 terminal and the AIN3 terminal of the second AD chip. The input terminals of the C-phase AC voltage signal processing unit are connected to the C-phase and N-phase outputs of the frequency converter, respectively, to collect the voltage signal VC of the C-phase and the voltage signal VN of the N-phase. The output terminals of the C-phase AC voltage signal processing unit output the voltage differential signals of the C-phase, namely the OUT-CP signal and the OUT-CN signal. The OUT-CP signal and the OUT-CN signal are respectively input into a pair of differential input terminals of the second AD chip, namely the AIN4 terminal and the AIN5 terminal of the second AD chip. The AC current sampling unit includes AC circuit sampling resistor R3, AC circuit sampling resistor R2, AC circuit sampling resistor R1, phase A AC current signal processing unit, phase B AC current signal processing unit, and phase C AC current signal processing unit. AC circuit sampling resistors R3, R2, and R1 respectively acquire the A-phase current signal, B-phase current signal, and C-phase current signal. The phase A AC current signal processing unit includes a current limiting circuit and an AC current amplifier; The input terminal of the phase A AC current signal processing unit is connected to both ends of the sampling resistor R3 to obtain the differential phase A current signal collected by the sampling resistor R3, namely the current signal IA+ and the current signal IA-. The current signal IA+ and the current signal IA- are connected to the input terminal of the AC current amplifier through the current limiting circuit. The output terminal of the AC current amplifier constitutes the output terminal of the phase A AC current signal processing unit, which is used to output the phase A current signal OUT-IA. The current signal OUT-IA is input to an AD channel AIN6 of the second AD chip. The circuit principles of the phase B AC current signal processing unit and the phase C AC current signal processing unit are the same as those of the phase A AC current signal processing unit. The input terminal of the B-phase AC current signal processing unit is connected to both ends of the sampling resistor R2 to obtain the differential B-phase current signal collected by the sampling resistor R2, namely the current signal IB+ and the current signal IB-. The output terminal of the B-phase AC current signal processing unit outputs the B-phase current signal OUT-IB, which is input to one AD channel AIN7 of the second AD chip. The input terminal of the C-phase AC current signal processing unit is connected to both ends of the sampling resistor R1 to obtain the differential C-phase current signal collected by the sampling resistor R1, namely the current signal IC+ and the current signal IC-. The output terminal of the C-phase AC current signal processing unit outputs the C-phase current signal OUT-IC, which is then input to one AD channel AIN8 of the second AD chip. The second AD chip is connected to the main controller via the SPI bus.

5. A high-precision frequency converter data acquisition terminal as described in claim 4, characterized in that: In the A-phase AC voltage signal processing unit, the protection unit includes fuse F1 and TVS tube D1, the current limiting circuit includes current limiting resistor RLIMIT1, the voltage divider circuit includes resistors R4, R5, R7, R9, R10, R8 and R6, and the RC anti-aliasing circuit includes resistor R11, capacitor C1, resistor R12 and capacitor C2. Pin 1 of fuse F1 is connected to the voltage signal VA, and pin 2 is connected to pin 1 of current limiting resistor RLIMIT1; one end of TVS diode D1 is connected to pin 2 of fuse F1, and the other end is connected to the voltage signal VN. Pin 2 of the current-limiting resistor RLIMIT1 is connected to pin 1 of resistor R6 via resistors R4, R5, R7, R9 and R10 connected in series. Pin 2 of resistor R6 is connected to the voltage signal VN. Pin 1 of resistor R6 is also connected to pin 1 of resistor R11, pin 2 of resistor R11 is connected to pin 1 of resistor R12, and pin 2 of resistor R12 outputs the voltage signal VIN-AP. One end of capacitor C1 is connected to pin 2 of resistor R11, and the other end is connected to voltage signal VN. Pin 1 of capacitor C2 is connected to pin 2 of resistor R12, and pin 2 is connected to voltage signal VN. The output voltage signal VIN-AN is generated at pin 2 of capacitor C2. The AC voltage amplifier includes amplifier IC4, capacitor C7, capacitor C10, capacitor C3, rectifier bridge B1, capacitor C4, capacitor C5, regulator IC1, capacitor C6, regulator IC2, capacitor C8, capacitor C9, regulator IC3, capacitor C11, and capacitor C12. The input terminals of rectifier bridge B1 are connected to voltage signal VA and voltage signal VN respectively, and the output terminals output power supply VINA and the first ground line GND1 respectively; capacitor C3 is the filter capacitor at the input terminal of rectifier bridge B1; capacitors C4 and C5 are both filter capacitors at the output terminal of rectifier bridge B1. The input terminal of voltage regulator IC1 is connected to power supply VINA and the first ground line GND1, and the output terminal outputs power supply VA1; capacitor C6 is the filter capacitor at the input terminal of voltage regulator IC1. The input terminal of voltage regulator IC2 is connected to power supply VA1 and the first ground line GND1, and the output terminal outputs power supply VA2; capacitors C8 and C9 are both filter capacitors at the output terminal of voltage regulator IC2. The input terminal of voltage regulator IC3 is connected to power supply VA2 and the first ground line GND1, and the output terminal outputs power supply VH; capacitors C11 and C12 are both filter capacitors at the output terminal of voltage regulator IC3. Voltage signals VIN-AP and VIN-AN are input to the IN and GND1 terminals of amplifier IC4, respectively. The VDD1 terminal of amplifier IC4 is connected to the power supply VH, the SHTDN terminal is connected to the first ground GND1, the GND1 terminal is connected to the first ground GND1, the GND2 terminal is connected to the second ground GND2, the OUTN terminal outputs the OUT-AN signal, the OUTP terminal outputs the OUT-AP signal, and the VDD2 terminal is connected to the power supply VCC. Capacitors C7 and C10 are the filter capacitors for the VDD1 and VDD2 terminals of amplifier IC4, respectively. The power supply VCC and the second ground GND2 are both provided by the power module.

6. The high-precision frequency converter data acquisition terminal as described in claim 3, characterized in that: The DC voltage divider network is a voltage sampling circuit composed of voltage divider resistors; the voltage isolation amplifier is model AMC1311BDWV; the current isolation amplifier is model AMC1301DWV; the first AD chip is model ADS1115; the main controller is model STM32F407VGT6; the temperature and humidity transmitter is model SHT30-DIS; the vibration transmitter is model ADXL345; and the wireless communication module is model ESP32-WROOM-32.

7. A high-precision frequency converter data acquisition terminal as described in claim 5, characterized in that: The current limiting circuit is a differential current limiting protection circuit composed of current limiting resistors; the AC current amplifier is model AMC1301DWV; the second AD chip is model ADS8688. The fuse F1 is model 0603L050YR; the TVS diode D1 is model SMBJ18CA; the amplifier IC4 is model AMC1311BDWV; the rectifier bridge B1 is model MB6S; the voltage regulator IC1 is model LM7812; the voltage regulator IC2 is model LM7805; and the voltage regulator IC3 is model AMS1117-3.3.

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