Estimation of residual common mode voltage in floating voltage measurement with differential voltage probe for high voltage power electroincs circuit

Funaki, Tsuyoshi; Hayashi, Katsuhiko

doi:10.1109/icsj.2018.8602435

Cited by 1 publication

(1 citation statement)

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“…A further disadvantage of HV differential probes is the typically very poor CMRR at elevated frequencies (above several MHz), limited by the amplitude and phase matching of the differential signal path [16], which inadmissibly deteriorates the measurement in WBG converter systems, e.g., shown in [17]. Different solutions to overcome these limitations have been proposed in literature, e.g., online or offline compensation of the CM influence on the measurement by subtraction of the resulting error in the measurement signal [18] or indirect characterization of the switching transient by integrating the measured switch current [14]. While these methods can help to improve the performance, they are complex to use and do not fully eliminate the measurement error.…”

Section: Introductionmentioning

confidence: 99%

High-Bandwidth Isolated Voltage Measurements With Very High Common Mode Rejection Ratio for WBG Power Converters

Niklaus

Bonetti

Stäger

et al. 2022

IEEE Open J. Power Electron.

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Galvanically isolated voltage measurements are becoming increasingly important for the characterization of converter systems with fast switching Wide-Bandgap (WBG) semiconductors. A very high Common Mode Rejection Ratio (CMRR) > 80 dB for frequencies up to several tens of MHz is required to accurately measure, e.g., the high-side gate-source or drainsource voltage in a half-bridge, or voltages on floating potentials as, e.g., found in multi-level converters. Common to all listed measurement scenarios is the fast changing reference potential, which acts as Common Mode (CM) disturbance. This article derives the minimum necessary CMRR at different frequencies to constrain the time-domain measurement error below a certain limit. Thereby, only the switched voltage and the voltage transition rate (dv/dt) of the CM disturbance are to be considered and not the actual converter switching frequency f sw . Afterwards, a galvanically isolated measurement system with a CMRR > 100 dB up to 100 MHz and an analog measurement bandwidth of 130 MHz is presented. Critical design aspects to achieve this performance are investigated. Compared to commercially available isolated voltage probes, the presented measurement system does not require any additional equipment like an oscilloscope to perform and visualize measurements, since the data is already digitized/sampled and thus can be transmitted directly to a host device (e.g., computer or monitoring system) with corresponding Graphical User Interface (GUI) software. Experimental verification in frequency-and timedomain confirms that the performance is on par with the best commercially available isolated voltage probes.

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