This blog documents the restoration, and conversion, of a 1965 Humber (Singer) Vogue to a fully electric vehicle. The Vogue will be powered by an 11kW(modified), 3 phase industrial AC motor, controlled by an industry standard Variable Speed Drive (VSD) or Inverter. To be able to produce the 400 volts phase to phase the VSD will need about 600 VDC of batteries. A big thanks to the contributors on the AEVA forum:

Friday, April 26, 2013

Some Vibration Testing and Thoughts

I have added a new search label to the blog - Vibration!

Someone on the AEVA forums had suggested that the vibration may be resonance in the motor mounting system. I had my heart set on this being the cause - alas no. I'd even measured up for motor cycle steering dampers.
Placing a jack with a block of wood under the centre of the motor frame very marginally decreased the vibration is accord with what you would expect in that it offered a bit of dampening to the real cause. I used my phone to record the subsonic audio coming from the car during axle stand testing. Here is a spectrum plot of the recorded audio with speed somewhere between 55 and 60 km/h.
The lowest peak occurs at about 76 38 Hz which is rotation frequency at 57 km/h - that fits. The next peak is at twice rotation frequency which suggests the universal joint as it rotates over the "top" on each side. The third and most prominent peak is at 118 Hz - which I can't explain - three times rotation frequency?
It still looks like interplay between the UJs and the motor/mounting.

Crawling around under the car travelling at 55-60 km/h (on stands) the vibration was almost non-existant at the diff end. The motor itself was the worst point. I could not visually see any runout consistant with this behaviour. I've had some really bad UJs in tailshafts in my life that didn't vibrate as badly as this apparently OK one.

Precision Balancing have a portable setup for analysing vibration that they use in the field - it may soon come to that.

I'm also thinking about CVs....

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