Modular 3-Port Isolated Current- and Voltage Measurement System for Advanced Converter Control

Precise isolated current and voltage measurement is a frequent task in measurement and control. 3- port isolation simplifies assembling of the measurement system. Typical applications are multichannel data acquisition, ground loop elimination, motor control and rapid prototyping. High common-m.de rejection ratios because of high rate of rise of voltages at switching (high switching speed of state-of-the-art semiconductors have rise and fall times typically less than 1 mus) could be reached by avoiding capacitive cross-coupling. The output signals are scaled signals (+/-10 V or 5 V range) suited directly for A/D-converters. This paper describes the concept of 3-port isolation in current- and voltage a measurement system which is a prerequisite for advanced converter control.