Search

CN-224203293-U - Isolated alternating current high-voltage signal acquisition circuit resistant to common mode interference

CN224203293UCN 224203293 UCN224203293 UCN 224203293UCN-224203293-U

Abstract

The utility model discloses an isolated alternating current high-voltage signal acquisition circuit resistant to common mode interference, wherein an isolated power supply module is an independent power supply for establishing electrical isolation between a high-voltage side circuit and a low-voltage side circuit. The input attenuation and clamping module is used for carrying out attenuation and amplitude clamping on the alternating current signal at the high voltage side. The isolation amplifying and signal converting module isolates and transmits the attenuated signal to the low-voltage side and outputs a low-voltage analog signal taking the ground of the low-voltage side as a reference. The buffering and filtering output module is used for buffering and filtering the signal, enhancing the driving capability, inhibiting noise and outputting a stable acquisition signal. According to the utility model, the high-voltage side fault voltage and surge are effectively blocked through electrical isolation, personnel and equipment are protected, and the reliability, control precision and robustness of the system under severe environments are improved by combining signal conditioning.

Inventors

  • TENG BO
  • YU YANG
  • SUN YUANBANG

Assignees

  • 大连美恒电气有限公司

Dates

Publication Date
20260505
Application Date
20260326

Claims (6)

  1. 1. The isolated alternating current high-voltage signal acquisition circuit resistant to common mode interference is characterized by comprising an isolated power supply module, an input attenuation and clamping module, an isolated amplifying and signal conversion module and a buffering and filtering output module; The output end of the isolation power supply module is respectively connected with the power input ends of the input attenuation and clamping module and the isolation amplifying and signal converting module, and is used for establishing an independent working power supply reference capable of electrically isolating the low-voltage side circuit from the high-voltage side circuit; The input attenuation and clamping module is connected with the isolation amplifying and signal converting module, can acquire a power supply of the isolation amplifying and signal converting module from the isolation power supply module, attenuates an input high-voltage side alternating current signal, and limits the amplitude of the attenuated alternating current signal within a preset safe voltage range; The isolation amplifying and signal converting module is used for isolating the AC signal attenuated at the high-voltage side and transmitting the AC signal to the low-voltage side, so as to output a low-voltage analog signal taking the ground at the low-voltage side as a reference potential; The buffer and filter output module is connected with the isolation amplifying and signal converting module and is used for buffering and filtering the low-voltage analog signal so as to enhance the driving capability and inhibit noise, and then outputting a stable analog voltage signal serving as an acquisition signal.
  2. 2. The isolated ac high voltage signal acquisition circuit of claim 1, wherein the input attenuation and clamping module comprises a first resistor, a second resistor, a third resistor, and a clamping diode; One end of the first resistor is connected with a high-voltage alternating current input signal end, the other end of the first resistor is connected with one end of the second resistor, the other end of the second resistor is connected with one end of the third resistor, and the other end of the third resistor is connected with the isolation amplifying and signal converting module; And two ends of the clamping diode are respectively connected with a +5V power supply and the isolation amplifying and signal converting module.
  3. 3. The isolated ac high voltage signal acquisition circuit of claim 2, wherein the isolated power supply module comprises an isolated power supply chip, a first capacitor and a second capacitor; the first pin of the isolation power supply chip is grounded, and the second pin is connected with a +24V power supply; One end of the first capacitor is grounded, and the other end of the first capacitor is connected with a +24V power supply; And one end of the second capacitor is grounded, and the other end of the second capacitor is connected with the output end of the isolated power supply chip.
  4. 4. The isolated ac high voltage signal acquisition circuit of claim 3, wherein the isolated amplifying and signal converting module comprises a first operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor and a fourth capacitor; Two power input ends of the first operational amplifier are respectively connected with +5V and +3.3V power sources; The same-direction input end and the reverse input end of the first operational amplifier are respectively connected with two ends of the sixth resistor, and the sixth resistor is connected with the clamping diode; the output end of the first operational amplifier is connected with the buffering and filtering output module; one end of the fifth resistor is connected with a +5V power supply, the other end of the fifth resistor is connected with one end of the seventh resistor, and the other end of the seventh resistor is grounded; one end of the third capacitor is connected with a +5V power supply, and the other end of the third capacitor is grounded; One end of the fourth capacitor is connected with the sixth resistor, and the other end of the fourth capacitor is grounded.
  5. 5. The isolated ac high voltage signal acquisition circuit of claim 4, wherein the buffer and filter output module comprises a second operational amplifier, an eighth resistor, a fifth capacitor, a sixth capacitor and a seventh capacitor; The same-direction input end of the second operational amplifier is connected with the output end of the first operational amplifier, and the reverse input end of the second operational amplifier is connected with the output end of the second operational amplifier; one end of the eighth resistor is connected with the output end of the second operational amplifier, the other end of the eighth resistor is connected with the sixth capacitor, and the power end of the second operational amplifier is connected with a +3.3V power supply; One end of the fifth capacitor is connected with a +3.3V power supply, and the other end of the fifth capacitor is grounded; the other end of the sixth capacitor is grounded; one end of the seventh capacitor is connected with a +3.3V power supply, and the other end of the seventh capacitor is grounded; one end of the eighth resistor is connected with the output signal end.
  6. 6. The isolated ac high voltage signal acquisition circuit of claim 5, further comprising a high impedance co-reference measurement front end network connected to the input attenuation and clamp module for establishing a reference for a high side ac signal; the high-impedance common reference measurement front-end network comprises a ninth resistor, a tenth resistor and an eleventh resistor; One end of the ninth resistor is connected with the high-voltage alternating current input signal end, the other end of the ninth resistor is connected with one end of the tenth resistor, the other end of the tenth resistor is connected with one end of the eleventh resistor, and the other end of the eleventh resistor is grounded.

Description

Isolated alternating current high-voltage signal acquisition circuit resistant to common mode interference Technical Field The utility model relates to the technical field of high-voltage electric signal detection, in particular to an isolated alternating-current high-voltage signal acquisition circuit resistant to common-mode interference. Background In the monitoring and control of industrial high-voltage equipment (such as a crane motor rotor loop and a frequency converter bus), high-voltage alternating current signals are often required to be collected and sent to a low-voltage microcontroller (such as an MCU) for processing. Traditional high voltage acquisition schemes generally adopt a resistor voltage division mode to directly sample, but have the following problems: 1. high-low voltage ground potential inequality The ground (gnd_hv) on the high voltage side (e.g., motor drive bus) and the ground (gnd_lv) on the low voltage side (e.g., MCU) may not be the same potential. Gnd_h may fluctuate strongly from gnd_lv to several tens, hundreds or even up to kv due to, for example, large currents, long cables, etc. If the isolation is not performed, common mode voltage is introduced to the acquisition circuit, and the acquisition of interference signals even damages the back-end circuit; 2. there is a problem of noise and interference The high-voltage environment is usually a high-noise environment, and the noise is coupled into a sensitive low-voltage side circuit through a power supply and a ground wire, so that the signal quality is reduced, the measurement accuracy is reduced, and even the system malfunction or breakdown is caused; 3. safety assurance problem Any circuit directly connected to the high voltage side, if connected to ground or the equipment enclosure, may break down the sampling circuit once the high voltage side fails, threatening equipment and personnel safety. Disclosure of utility model The utility model provides an isolated alternating current high-voltage signal acquisition circuit resistant to common mode interference, which aims to overcome the technical problems. In order to achieve the above object, the technical scheme of the present utility model is as follows: An isolated alternating current high-voltage signal acquisition circuit resistant to common mode interference comprises an isolated power supply module, an input attenuation and clamping module, an isolated amplifying and signal conversion module and a buffering and filtering output module; The output end of the isolation power supply module is respectively connected with the power input ends of the input attenuation and clamping module and the isolation amplifying and signal converting module, and is used for establishing an independent working power supply reference capable of electrically isolating the low-voltage side circuit from the high-voltage side circuit; The input attenuation and clamping module is connected with the isolation amplifying and signal converting module, can acquire a power supply of the isolation amplifying and signal converting module from the isolation power supply module, attenuates an input high-voltage side alternating current signal, and limits the amplitude of the attenuated alternating current signal within a preset safe voltage range; The isolation amplifying and signal converting module is used for isolating the AC signal attenuated at the high-voltage side and transmitting the AC signal to the low-voltage side, so as to output a low-voltage analog signal taking the ground at the low-voltage side as a reference potential; The buffer and filter output module is connected with the isolation amplifying and signal converting module and is used for buffering and filtering the low-voltage analog signal so as to enhance the driving capability and inhibit noise, and then outputting a stable analog voltage signal serving as an acquisition signal. Further, the input attenuation and clamping module comprises a first resistor, a second resistor, a third resistor and a clamping diode; One end of the first resistor is connected with a high-voltage alternating current input signal end, the other end of the first resistor is connected with one end of the second resistor, the other end of the second resistor is connected with one end of the third resistor, and the other end of the third resistor is connected with the isolation amplifying and signal converting module; And two ends of the clamping diode are respectively connected with a +5V power supply and the isolation amplifying and signal converting module. Further, the isolation power supply module comprises an isolation power supply chip, a first capacitor and a second capacitor; the first pin of the isolation power supply chip is grounded, and the second pin is connected with a +24V power supply; One end of the first capacitor is grounded, and the other end of the first capacitor is connected with a +24V power supply; And one end of the second capac