Nissan Leaf motor EMC

[arber333]

YA! I finally managed to find someone with RF spectrum analyser. I have been searching for the thing to get a feeling for EMI at motor load.
We setup the gizmo inside a building with the antenna on the outside.
Then i performed a low speed drive on the parking lot outside. There was actually no much interference detected here.

Next i decide to open the hood and perform a simulated hill driveoff. That meant i was holding a parking brake while trying to start from full stop. This is actually the worst EMI condition with amps flying but no significan voltage in RST cables. My inverter was operating at 6kHz PWM with full FOC code from Lebowski. I have phase cables inside metal socks as well as some of the DC cable. A lot of cable is passing under the car and is covered by alu cover. Motor is under a lot of metal covering and inverter also has inox cover over contacts. Everything is properly grounded with at least 6mm2 copper braid.

Resulting EMI spectrum actually surprised me. We ve got a wide range of noise just in the VHF area 184Mhz firemen and other first responders use! My bad!
I will probably go to the local fire brigade and try to get a feel of actual EM noise during one of their excercises. Probably my car has the ability to swamp their portable radios if i am too close.

So for now gorge your eyes on the VHF spectrum disturbance . Hardcore no?

[damian.lo]

It could be true - I hear it into FM radio
When my Leaf motor starts spinning I hear noise in speakers. The same situation is when regen is active. I don't hear any distrurbances when speed is constant - no matter hi or low.
So - there are also mine EMF investigations. For now I don't know what to do with this...

[arber333]

It could be true - I hear it into FM radio
When my Leaf motor starts spinning I hear noise in speakers. The same situation is when regen is active. I don't hear any distrurbances when speed is constant - no matter hi or low.
So - there are also mine EMF investigations. For now I don't know what to do with this...

In my case i dont hear my motor inside the FM radio. Seems harmonics is higher up into 180Mhz range.
That EE guy who operated the spectrum analyzer said that 6Khz PWM can certainly create much higher bumps into the spectrum. He said power supplies and converters are major EMI contributor here...

Well you can do several things with your DIY EV i saw also OEMs doing.
1. Put your phase cables into shielded socks with common GND connected to car chassis
2. Both motor and inverter need to be connected to chassis by at least 6mm2 cable.
3. You can put mesh or foil over your DC cables from front-back. However that might be expensive. There is an old trick though. You go and twist DC cables so that you make twisted pair. I twisted them at least once per 300mm. You need some more cable length that way, but cable EMI are greatly reduced that way.

Dont forget your car sheet metal also acts as a "cage" and very minor correction or cable joints can influence RF.

[damian.lo]

Thanks, maybe fastest way will be to connect ground to phase shields, since my cables are already made like this. My fault was to don't connect them at beginning. I will try this and report.
Inverter - motor - DCDC are already connected to GND with thick cable (removed from gas engine) at least 50 sq mm or even more.