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Old 07-05-2008, 07:25 PM
michael30.06 michael30.06 is offline
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Default Too much time to think!

Well I am still waiting on the powers that be in the Department of Transport to tell me the requirements for road registering an all electric motorbike for road use here in Queensland. So while I have been waiting, I have spent my time looking at how to reduce costs of the overall project. A question comes to mind. Why can't we use a second hand 240V AC motor as they are often available for free or very cheap from garage sales in used household appliances. Sorry if this is a dumb question but like I said Too much time to think!
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  #2  
Old 07-05-2008, 10:59 PM
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Default Re: Too much time to think!

THe problem is they are made to go at 50Hz which means you only get 1 cruise speed, a couple of guys at the AEVA site have used a specific type of industrial motor to do it but I don't think normal AC motors work that well.
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Old 07-06-2008, 03:16 AM
michael30.06 michael30.06 is offline
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Default Re: Too much time to think!

Ok so the flexibility that seems to be in a DC motor which can be run at 2X it's normal voltage does not extend to an AC motor in this way. As you can see I am winging it in a big way as far as understanding the fundamental process. Thankyou for the reply
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Old 07-06-2008, 05:22 AM
manic_monkey manic_monkey is offline
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Default Re: Too much time to think!

its my understanding that in an AC motor, voltage and frequency are linearly related, mostly to prevent magnetic saturation.

so, if the motor is 1800rpm @240v 50hz then then 900rpm is @120v 25hz

you should be able to run the motor past its rating, but you cant do it using hz or voltage alone, it must be both, in the correct measure. so, for the motor above, you could run it at 3600rpm, providing you could supply it with 480v and 100hz.

Ive never actually run an AC motor past its rating, but i always thought that because of their simplicity they should be very tolerant to overload. i would imagine its limits would be the class of insulation in the field windings
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Old 07-06-2008, 03:54 PM
michael30.06 michael30.06 is offline
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Default Re: Too much time to think!

Ok that explains why we don't see more washing machine motors in use out there, it seems to be either lots of voltage or back to the gearbox and it's extra weight, Possible uses in the Mtb range of vehicles but not really the 250cc motor bike I would like. Thanks for the reply
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