Loading ...
Sorry, an error occurred while loading the content.

Motor Question

Expand Messages
  • Marchelle
    The Sparrow motor is rated at 150V. I have used 14 batteries at one point - 168V. I know the Kilovac controller can go somewhat higher - maybe 180V? My
    Message 1 of 2 , Nov 1, 2010
    View Source
    • 0 Attachment
      The Sparrow motor is rated at 150V. I have used 14 batteries at one point - 168V. I know the Kilovac controller can go somewhat higher - maybe 180V? My question is... what allows an ADC motor to go over it's voltage rating. And just how high can it go? Or this really all about RPMs?

      Thanks for your insight.

      Matt Wilson
      #159
    • davide
      ... What you are forgetting is that the motor is NOT connected directly to the battery pack: there is a motor controller in between. The motor controller
      Message 2 of 2 , Nov 1, 2010
      View Source
      • 0 Attachment
        > The Sparrow motor is rated at 150V. I have used 14 batteries at one
        > point - 168V.

        What you are forgetting is that the motor is NOT connected directly to
        the battery pack: there is a motor controller in between.

        The motor controller _lowers_ the voltage and _raises_ the current, by
        an amount set by the present conditions. The motor controller works like
        a step-down transformer, except that it works at DC instead of AC.

        > what allows an ADC motor to go over [its] voltage rating.

        It never does.

        > And just how high can it go?

        Like the man said: 150 V.

        > Or this really all about RPMs?

        Yes, RPM does have a role to play in this equation.

        Roughly speaking, the voltage across a DC motor is directly proportional
        to its RPM. (More precisely, it is somewhat higher than that, in order
        to generate torque.)

        The motor controller takes the full pack voltage (156 V nominal) and
        drops it down to the voltage that the motor needs at that RPM. So, when
        you're stopped, the motor voltage will be just a few volts, even though
        the pack voltage is about 156 V. When you're going at highway speed, the
        motor voltage may by 50 V or so, even though, again, the pack voltage
        is about 156 V.

        Conversely, the motor controller raises the motor current compared to
        the battery pack current. So, when you're stopped but starting to move,
        the motor current may be 400 A, even though the pack current may be only
        about 50 A. The torque of a DC motor is proportional to its current.

        The only time that the motor voltage is the same as the pack voltage
        (and the current is the same in the motor as in the pack) may be when
        you're "flooring it", and the battery is nearly empty: then the motor
        controller gives the motor all the pack can give. That's pretty rare.

        Davide
      Your message has been successfully submitted and would be delivered to recipients shortly.