Insulation Resistance Monitoring for HVDC systems in automotive applications

Abstract

ABSTRACT As electric vehicle and renewable-energy systems push toward ever-higher voltages, reliable insulation resistance monitoring (IRM) becomes critical to ensure safety, prevent insulation degradation, and maintain system availability. Key IRM performance parameters include common-mode and delta-voltage excursions (which drive dielectric stress, insulation aging, and electromagnetic compatibility risk), measurement time (set by resistance–capacitance time constants, crucial for real-time fault detection), and measurement accuracy (to avoid false positives/negatives). Results show that under balanced conditions the resistor-switching Volvo TVPDCU exhibits Δ-voltage excursions up to 263 V with floating-bus bias under 15% of pack voltage, whereas the pulse-based Bender iso175 confines ΔV to 11.3 V and holds bias within 7%. In single-pole fault tests, TVPDCU drives the healthy pole up to ≈ 16.9% of pack voltage (simulated hand-to-hand currents peaking at ≈ 1.57 A), while Bender limits it to ≈ 10% (currents ≈ 1.01 A). Both methods generate discharge energies exceeding the ISO 0.2 J safety threshold for voltages above 600 V. The balanced condition discharge energies span ≈ 0.20˘0.464 J (TVPDCU ≈ 0.02 J higher), and healthy-pole energies in fault tests range ≈ 0.32˘0.89 J, with faulty pole. Despite manual data extraction and component tolerances, rigorous recalibration and transparent procedures ensure reproducibility and validity of the results. These findings inform IRM selection trade-offs voltage headroom, real-time responsiveness, accuracy, electromagnetic compliance and insulation longevity, and point to future work on active balancing, novel algorithms, and material effects under high Δ-voltage stress.