A Digital Isolated High Voltage Probe for Measurements in Power Electronics

For the development and optimization of highly efficient power electronic systems, it is essential to precisely measure voltage signals of fast-switching high voltage semiconductors. Due to various reasons off-the shelf high voltage differential probes are not suitable for those measurements. In this paper a digital isolated high voltage probe, especially designed for measurements in power electronics, is presented. The analog to digital conversion of the input signal is already done at the probe, the galvanic isolation is done on the digital lines. In the paper a detailed explanation about the development is given as well as an extensive characterization of a built prototype. The prototype withstands a permanent isolation voltage of 1500 V. It continuously streams 18 bit ADC data at a sampling rate of 5 MS/s. Special care is taken to reach a flat frequency response and a superb linearity up to the maximum differential input voltage of 1500 V.