利用计时器芯片和脉冲占空比调制的光电式电压传感器

An optoelectronic voltage sensor based on a timer chip and pulse duration ratio modulation is proposed and investigated experimentally in order to measure direct current (dc) high voltage.The dc high voltage to be measured can be proportionally converted into the voltage sensing signals modulated by pulse duration ratio by use of the ICM7555 timer chip.The optical sensing signal is generated by a light-emitting diode (LED) which is modulated by the above pulse signal,and transmitted to a photo-detector and signal processing circuits through a piece of plastic optical fiber.The dc voltage sensing signal to be measured can be demodulated from the measurement of the output pulse duration ration.The comparison analysis of relative errors has been conducted for the sensing schemes respectively based on pulse frequency modulation and pulse duration ratio modulation,and relative errors are smaller for the duration ration modulation than those for the frequency modulation.The dc high voltage with amplitude of 10 kV has been measured experimentally,and the fiducial error of the experimental data is less than 0.6%.