Radiofrequency Immunity Issues in Electric Vehicles — Testing Can Find That

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July 26, 2023

The International Energy Agency reports that over 10 million electric vehicles (EVs) were sold in 2022, representing 14% of all new-car sales. The numbers keep climbing. In 2021 it was 9%, and in 2020 it was less than 5%. In the US alone, EV sales increased 55% in 2022.

The rapid adoption of EVs is a product of the steadily improving technology that makes EVs practical and desirable. In regular use, EVs seem to check all the boxes: zero atmospheric emissions, fewer moving parts to fail, quiet operation – a boon to personal transportation.

Like any vehicle, EVs operate in a world subject to extremes. Temperature and moisture are obviously given to extremes, but the electromagnetic (EM) environment is rich with fields and transients that can be extreme in unpredictable ways. EVs rely on complex electronics to react to the driver, interpreting signals in real time from the accelerator, brake pedal, and steering column to control the heavy currents required to operate the drive motors and mechanical systems.

Electronic vehicle control has come a long way since the early 1970s, when first-generation automotive electronics were found vulnerable to radiofrequency (RF) signals. The original equipment manufacturers (OEMs) worked with their suppliers to improve system immunity to electromagnetic interference (EMI). 

Both the technology and the understanding of EMI have greatly improved since then, but the concern is the same. Elite’s Automotive EMC Testing Specialist Stan Dolecki has been involved in testing vehicles with internal combustion engines (ICE) for many years and understands potential interference risks.

Elite Automotive Specialist Stan Dolecki

“Radiated and conducted immunity testing has always been done on automotive components and whole vehicles, and the concern is greater with EVs,” Stan explained. “The interfering signal can come from anywhere, including within the vehicle.” EMI can come from a steady RF field, like a broadcast signal, or it can be a transient spike like an electrostatic discharge (ESD). “One of the major sources of ESD, for example, are serpentine belts. They build up a charge and create transients that affect microprocessor circuits. Transients disrupt logic signals and cause random failures,” Stan said.

A host of automotive EMI immunity standards address the applicable RF levels and the test procedures used in verification. ISO 7637-4 is one such standard, dealing with conducted and coupled electrical disturbances, testing for low-frequency ripple in an EV’s DC supply brought on by external disturbances. Electronic components are tested under standards LV124 (for 12VDC systems) and LV148 (for 48VDC systems). Volkswagen (VW 80000) and Ford (FMC 1280) maintain their own corporate standards to test the resiliency of electronic components, as do other original equipment manufacturers (OEMs).

All of this demonstrates the commitment to safe and reliable operation made by the automotive industry. “EMI immunity is a huge part of the test sequence for EVs,” Stan explained. “We can’t take the risk of an engine failure or a vehicle-control failure when an unseen RF signal or transient is there. The tests we do are thorough and well-documented. The manufacturers of the vehicles and their components rely on this throughout the development process.”

A car on the dynamometer in Elite’s whole-vehicle EMC test chamber

Elite’s lab runs tests at the bench level for components like voltage converters, regulators, and charging systems, and has a whole-vehicle test chamber equipped with a dynamometer in the floor to test a vehicle running under road conditions. “Complete testing is important, from the component level on up,” Stan said.

Contact Elite for more information on RF immunity testing. Put Elite’s deep experience and well-earned industry confidence to work for you as you verify your automotive electronic components.

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