Whitepaper

Electric Vehicle Ripple Disturbances

Published by Ametek CTS

This technical note from AMETEK CTS focuses on the origins, risks, and testing requirements of ripple disturbances in electric vehicle high-voltage systems. A ripple is an AC disturbance superimposed on a DC supply, primarily generated by the switching operations of inverter components during acceleration. The document explains that voltage ripples of up to 15 Vp can induce current ripples exceeding 300 Ap, and that such disturbances pose real dangers — including triggering battery management system faults, causing complete vehicle power loss, and physically damaging input filters in DC-DC converters. A central challenge discussed is the very low impedance of components like HV batteries and inverters, which can demand peak test currents well beyond 200 Ap and, in the case of inverters at resonance, theoretically up to 4800 Ap — requiring the test voltage to be intelligently limited based on the component's impedance curve to avoid destroying the device under test. The document maps the applicable standards, identifying ISO 21498-2 as the dominant international benchmark, alongside ISO TS 7637-4 and various OEM standards from Volkswagen, Mercedes-Benz, BMW, PSA, Renault, and Nissan, with test frequencies ranging from 10 Hz to 300 kHz and voltage amplitudes up to 40 Vp. Preferred test setup guidance favors transformer-based coupling for galvanic isolation over direct coupling. The note concludes with a ten-point checklist for selecting a ripple test solution, covering DC voltage and current ratings, impedance characterization, current limiting, safety, automation, and future upgradeability.