AC Induction and BLDC(brushless DC) Motor Voltage Comparison Question

Discussion in 'General Electronics Chat' started by kazafken, Aug 29, 2010.

  1. kazafken

    Thread Starter New Member

    Jun 19, 2008
    8
    0
    Hi,forumers!
    Is it true that the AC induction motor needs a higher voltage supply to operate while DC motor (such as BLDC) needs lower voltage supply?

    Currently,researching on various types of motors possible for electric vehicle. as i know, AC motors tend to be around 300-400V while most dc motors only varies around 96V-100++V

    Due to the fact of implementing batteries,the amount of it may affect weight and charging time coz higher voltage = more batteries.

    thanks in advance,
    kazafken.
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Well, you will not use many batteries in series to achieve, for example, 120VDC but you can use one battery and a step-up (boost) DC-DC converter. The number of batteries will be dependent on the power rating of the motor, the desired working time and the capacity of the batteries.
     
  3. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    When you get to higher powers, tens to hundreds of kilowatts, DC motors are generally higher voltage as well.

    It's largely down to current - a 100V motor will take four times the current than a 400V motor for the same power.

    With lower currents, the switching transistors dissipate less power, and there are less losses in the wiring.

    Also, for vehicle use, a number of small batteries operating in series at lowish currents will generally work better than a low voltage, high current setup.

    The Amp-Hour rating of most batteries depends on the charge and discharge rates, and lower currents give higher capacities.
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Same principle for why industrial building with 480V 3 phase use one leg of it as 277V to power the fluorescent and HID lighting.

    A #12 AWG wire is rated for 20A so long as there's a limited # in a piece of conduit. 20A @ 277V will operate a lot more fixtures than it would 120V ones so there's a great savings in wiring costs.
     
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