Isolation-type voltage collecting circuit

Abstract

The invention relates to an isolation-type voltage collecting circuit. The isolation-type voltage collecting circuit comprises an input voltage adjustment circuit, a voltage-pulse width transformationcircuit, a pulse transformation control circuit and a pulse width signal isolation transmitting circuit which are on the input side, and further comprises a pulse width signal isolation receiving circuit, a pulse width-voltage transformation circuit and a transformation pulse signal generation circuit which are on the isolation side. The input end of the input voltage adjustment circuit is connected with the input voltage; the input voltage adjustment circuit, the pulse transformation control circuit and the pulse width signal isolation transmitting circuit are connected to the voltage-pulsewidth transformation circuit; the transformation pulse signal generation circuit is connected to the pulse transformation control circuit; the pulse width signal isolation receiving circuit is connected with the pulse width-voltage transformation circuit; and the voltage-pulse width transformation circuit comprises a charging resistor, a charging control switch device and a capacitor which are connected in series. The collecting results are accurate, the working stability and reliability of voltage isolation collecting are high, the collecting circuit is simple, and the manufacturing cost is low.

Description

technical field [0001] The invention relates to the technical field of voltage acquisition, in particular to an isolated voltage acquisition circuit. Background technique [0002] With the rapid development and popularization of power electronics technology in various fields, the demand for voltage acquisition and measurement applications is becoming more and more extensive. For the collection of high voltage and high current, in order to ensure safety and reduce interference, electrical isolation between the collected circuit and the control circuit is usually required. In many fields such as inverter power supply, power conversion, motor control, high-voltage line detection, industrial process control and measurement system, in order to complete accurate closed-loop feedback control, it is necessary to respond quickly, with high reliability and high safety. The voltage acquisition measurement realizes electrical isolation between the power supply end of the collected circ...

AI Technical Summary

Problems solved by technology

[0004] The integrated isolation amplifier module realized by magnetic coupling isolation or capacitive coupling isolation, such as AD company's magnetic isolation amplifier AD202 and BB company's capacitive coupling isolation amplifier ISO122, such products are expensive, voltage isolation capability, reliability and response speed limited by the module itself

[0005] Linear optocoupler isolation methods, such as BB's ISO100 and AVAGO's HCNR200, use light-emitting diodes (LEDs) to couple with two photodiodes, one way is fed back to the input end, and the other way is coupled to the output end. After laser adjustment and careful matching, the linearity and The stability is good, but the isolated acquisition is realized by simulating a linear optocoupler. Since the coupling multiple is not a fixed value but an interval, the circuit consistency is poor. In practical applications, recalibration or additional calibration adjustment of circuit parameters is required. circuit, resulting in complex circuit, low voltage acquisition accuracy, slow response speed, and the price of linear optocoupler is still high

[0006] Ordinary optocoupler isolation acquisition, directly use one or two ordinary optocouplers, and use its approximate linear amplification function to achieve isolation acquisition, but ordinary optoelectronic isolation circuits cannot satisfy the linear relationship and the discrete type is larger, so accurate results cannot be collected

[0007] Modulation and demodulation mode, the measured voltage is frequency modulated (V / F mode) or pulse width modulated (PWM mode) to form a frequency or pulse width signal proportional to the measured voltage, which is transmitted to the isolation side through the isolation device. The isolated side restores the measured voltage information through demodulation and low-pass filtering. In this way, the circuits on the input side and the isolated side are more complicated, the reliability is poor, and the biggest limitation is the slow response speed.

[0008] In short, when the acquisition voltage input terminal needs to be isolated from the acquisition result output terminal, it is usually achieved through magnetic isolation, capacitive isolation, or optocoupler isolation. However, the existing acquisition methods require a large number of components and require additional calibration or other methods. Auxiliary circuit, low reliability, slow response speed, insufficient precision, expensive and other deficiencies

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