Hi Amund,
In my experience it ends up being the dV/dt (and some di/dt) from the driver circuit - essentially a very large digital output! Motors tend to have quite a large capacitance from windings to case through which current will flow, using the shield as a return. I would try: * Use current probes around cable to identify noisy ones * Cable shielding with full shield termination to metal chassis at both ends * Ensure metal case of driver (and therefore shields of cable) has a capacitor (voltage rating!) back to DC negative of the driver to return shield currents back to point of creation * Full shielding of driver enclosure * Common mode choke on output to motor (bulky!) * Check for noise on low voltage control wiring leaving the motor driver - this is a very common problem in traction control / automotive inverters. Apply filtering. Happy hunting. All the best James James Pawson Managing Director & EMC Problem Solver Unit 3 Compliance Ltd EMC : Environmental & Vibration : Electrical Safety : CE & UKCA : Consultancy www.unit3compliance.co.uk <http://www.unit3compliance.co.uk/> | [email protected] <mailto:[email protected]> +44(0)1274 911747 | +44(0)7811 139957 2 Wellington Business Park, New Lane, Bradford, BD4 8AL Registered in England and Wales # 10574298 Office hours: Every morning my full attention is on consultancy, testing, and troubleshooting activities for our customers' projects. I'm available/contactable between 1300h to 1730h Mon/Tue/Thurs/Fri. For inquiries, bookings, and testing updates please send us an email on <mailto:[email protected]> [email protected] or call 01274 911747. Our lead times for testing and consultancy are typically 4-5 weeks. From: Amund Westin <[email protected]> Sent: 05 November 2024 05:04 To: [email protected] Subject: [PSES] BLDC motors - EMI problems We have a BLDC motor (600VDC/50A - Brushless DC motor) in a test setup and I suspect that it is contributing with a lot of broadband noise on both radiated and conducted emission. If anyone has worked with the same problem and has some good hints on how to go about reducing the noise, I would be happy to receive tips. I have little experience with motors and EMI problems. BR Amund _____ This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to [email protected] <mailto:[email protected]> All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/[email protected]/ <https://www.mail-archive.com/[email protected]/%20> Website: https://ewh.ieee.org/soc/pses/ <https://ewh.ieee.org/soc/pses/> Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) <https://ewh.ieee.org/soc/pses/list.html> List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] <mailto:[email protected]> Rick Linford at: [email protected] <mailto:[email protected]> For policy questions, send mail to: Jim Bacher at: [email protected] <mailto:[email protected]> _____ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC <https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1> &A=1 -- This email has been checked for viruses by AVG antivirus software. www.avg.com - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to [email protected] All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/[email protected]/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] Rick Linford at: [email protected] For policy questions, send mail to: Jim Bacher: <[email protected]> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
