Study Ang Design Of Current Sensor Used In High Voltage Power Supply System

With the rapid development of power electronic technology,the high voltage power supply system become the research focus.In order to ensure the safety and stability of high voltage power supply system,the current of important branch in high voltage power supply system need to be measured.Current sensor with high performance is required.This paper designed new current sensors,which has good temperature stability,wide measuring range,and high precision characteristics.A prototype was designed in this paper based on simulation and experimental,which is applied to high voltage electrostatic dust precipitator for experimental research.Specific work is as follows:1.The new current sensor consists of double core probe.The inner ring core works in bidirectionally saturated fluxgate principle for the measurement of DC and low frequency AC.The outer toroidal core is used as a current transformer for higher frequency application.Bidirectionally saturated fluxgate principle is used in this sensor to achieve better temperature characteristic for high current measurement.This paper improved theoretical and experimental analysis of bidirectionally saturated fluxgate principle,and broadened the measurement range and measurement precision of the method.2.This paper proposed a wide range current detection method based on the theoretical research results of bidirectionally saturated fluxgate principle: According to application and different requirements of high voltage power supply system,sampling design of detection circuit is also different.when response time requirement is not high,initial sampling time of the detection circuit delays half cycle,then the data is valid;For such applications that the reaction time demands higher,When the measured current is greater than the critical current,initial half cycle sampling data of detection circuit is valid,and when the measured current is less than the critical current,initial half cycle sampling data of detection circuit is invalid.The size of the measured current and critical current is determined by the estimated sampling resistor.Compared with traditional methods,this method avoids excessive excitation circuit and detection circuit components because of two different principles combination.Related detection quantity is little,so the data processing is simple and volume of the sensor is small.3.The proposed new current sensor was designed as follows: According to choice of core material and performance requirements of the sensor to select suitable core model and design structure of sensor probe.Driver circuit and detection circuit is designed based on detection method of the new current sensor.A current sensor prototype was designed,which broadened the current measuring range and improved the performance of the sensor.4.The new current sensor used in high voltage power supply system measured load current and harmonic current.The simulation results have good agreements with the test results,which show that the current sensor can satisfy testing requirements of high voltage power supply system.