Design, construction and calibration of the current sensor for medium frequency high-power electronic applications

Abstract

The paper discusses design methodology, constructional alternatives and calibration procedure of current sensor suited for high-power semiconductor systems operated at medium switching frequencies (industrial contact and contactless power chargers). Even there are several types of the sensor on the market, for medium frequency operation they usually exhibit problems with measured signal and its postprocessing. Proposed sensor is designed for a current up to 200 A and 120 kHz and is based on current transformer principle. Design procedure is focused on winding analyses and its impact on operational characteristics. In order to verify proper choice of magnetic core and windings distribution, finite element analysis have been provided to verify magnetization and saturation of sensor core. Consequently, the internal structure of the sensor and its construction is being described, while it is considered that the sensor is equipped with an electronic unit in a common housing. The electronic transducer evaluates the measured data and produces the digital output signals, which are easy to transfer even to a long distance. Prototype of constructed sensor has been undertaken to experimental measurements for given frequency range in order to evaluate quality factors and accuracy. At the end of the paper, the required process of calibration was provided through the evaluation of the algorithm required by digital logic of the sensor.