脉宽调制整流器中模拟信号的远距离隔离传输

Isolated Transportation of Analog Signals for Long-distance in Pulse-Width-Modulation Rectifier

提出了一种适用于高压环境下远距离传输模拟信号的方法。利用AD650构成压频和频压转换电路,先将模拟信号转换成±5 V,后经压频电路将电压信号线性变成一定频率的方波脉冲列,并经光纤传输到远处的控制中心。在控制中心再将脉冲列送入频压转换电路还原成电压信号,最终送入AD芯片转换成数字信号送入控制器进行处理。设计了电路结构和参数,并进行了实验。实验结果表明:所设计方案可以有效地传输模拟信号,既无衰减,又有良好的抗干扰能力。传输距离可达200 m,传输过程中的延时小于20μs。

A method was proposed to transport isolate analog signals for long distance in high-voltage system. In this paper,the chip AD650 was adopted to construct a voltage-frequency conversion circuit and frequencyvoltage conversion circuit. The analog signal was converted into a ± 5 V firstly,and then the voltage signal was linearly converted into a square wave pulse-train with certain frequency by the voltage-frequency circuit. The pulse train was transported to distant control center through optical fiber. In the control center the pulse train was reduced to the voltage signal by a frequency-voltage circuit. Finally the voltage signal in the distant position was put into an A / D chip to be converted into digital signal,and then was transmitted to the controller for processing. The circuit structure was designed,and the method to calculate the circuit parameters was given. The experimental results show that the scheme can effectively transmit analog signals without attenuation and with good anti-interference ability. The transmission distance can reach 200 meters with the delay of less than 20 us.