2022-2023 Meeting Reports

Noise Sources in Electric Vehicles

September 22, 2022

Ms. Karen Burnham

Electromagnetic Applications, Inc

The Phoenix Chapter of the IEEE EMC Society had its first in-person meeting since the pandemic! The chapter met on September 22, 2022, at Compliance Testing, in Mesa AZ.  The meeting was well-attended considering the pandemic, with a count of 26 people.

The evening started at 05:30 pm with a social gathering and dinner.  Brent Treadway of TMS Marketing arranged for a wonderful catered BBQ dinner and he home cooked a vegetarian lasagna!  Dinner was followed by opening announcements and chapter business directed by Glen Gassaway, chapter chair.  Of particular interest was that Phoenix will host the 2024 EMC Symposium (volunteers are needed!). The announcements were followed by the usual around-the-room introductions, including the companies that are hiring and individuals looking for work.

Introductions were followed by a presentation entitled ‘Noise Sources in Electric Vehicles’ presented by Ms. Karen Brunham of Electro Magnetic Applications, Inc. (EMA), located in Lakewood CO. Ms. Brunham is a principal scientist at EMA, has a wealth of experience in the aerospace/defense and automotive industries, and holds a MS in electrical engineering.

Ms. Burnham indicated that the major cause of emissions within and from an electric vehicle is caused by the insulated gate bipolar transistors (IGBTs), considering the very high voltages and current that need to be switched. Slowing down the rise/fall times will help substantially, but that could result in loss of efficiency. Omitting susceptible components from the EV high Voltage bus removes conducted emissions/susceptibility as being a concern. Locating the HV system in very solid metal structures reduces radiated emissions. It’s important to keep parasitic capacitance in mind when positioning the IGBTs so emissions will not couple across filters. Counter to popular opinion, brushed motors can make a lot of noise, so brushless or permanent magnet motors should be used. Sometimes RF from the IGBTs can couple to the driveshaft or other mechanical structures, so proper placement and shielding are crucial.  To summarize, shielding should be as good as a military grade design, cables should be as short as possible and routed close to chassis, return lines must be run next to power lines and there should be a single point ground, and all high voltage enclosures should be well-bonded to chassis.

For all vehicles, CISPR 12 is the applicable standard for off-board radiated emissions and CISPR 25 is the applicable standard for on-board components. CISPR 36 is applicable to EVs only. ICNRP 1998/2010/2020 controls personnel exposure to radiated (magnetic) fields.

After the presentation, Glen Gassaway thanked Ms. Burnham for he very interesting presentation!  The meeting was closed at 8:25.

We are grateful to Compliance Labs in Mesa AZ for hosting and providing their facilities for this event.