DC Motor

Discussion in 'The Projects Forum' started by simon_ravyts, Mar 19, 2014.

  1. simon_ravyts

    Thread Starter New Member

    Mar 19, 2014
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    Hello

    For my master thesis I am repairing an old (1991) EV in an educational way. I am using a buck converter to control the input voltage. So far, so good this is already working quite fine. The problem that I am having is that i can't find the documentation of the motor that has been used in the EV. It's a DC series motor, 11kW from Leroy Somer model: T22, n° 716092/12, 85V, 150A, 2850tr/min. To calculate the ripple in the current etc. I would need the inductance L of the inductor .

    Does anyone has experience with this kind of motors or could you give a guideline value, based on a similar motor?

    Simon
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I wouldn't have thought that a series motor would have been used in a EV?
    A series motor essentially operates in a run away condition, the max rpm is governed by the load and friction at a particular voltage.
    Max.
     
  3. John P

    AAC Fanatic!

    Oct 14, 2008
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    My understanding is that a series motor was the traditional (pre-electronic control) type for traction applications. The feature that made it useful was that at standstill and low speeds, the torque would be very high, as the more current through the armature, the more magnetic field the stator would develop, and in theory torque is proportional to the two currents multiplied together. I think that often, a motor would be used in series mode for starting a vehicle, then be switched over to shunt mode later, with a bank of resistors to limit stator current. Or if the vehicle had multiple motors, they'd be switched (or the field windings would be switched) into some setup where they'd all be in series. Kind of like shifting gears in a car, but done electrically.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Yes, a automotive starter is an example of a series motor, but it is always operated under load, an example of the high rpm reached by an unloaded series motor is the vacuum or power hand tool, router motors that can reach 24krpm.
    In a traction type of application it is normally loaded continuously.
    Max.
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Series motors are awesome for traction apps. There's always enough load.

    Regarding the O.P's question, the inductance of an 11kW DC series motor will be enormous. Pretty much you can assume zero current ripple with any high freq PWM controller. Unless you plan to use 50 Hz PWM or something.
     
    Metalmann likes this.
  6. Metalmann

    Active Member

    Dec 8, 2012
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    "Yes, a automotive starter is an example of a series motor, but it is always operated under load, an example of the high rpm reached by an unloaded series motor is the vacuum or power hand tool, router motors that can reach 24krpm."


    As far as I've heard, router motors are usually AC. Right?
     
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    All I've ever used or seen are a 'universal' motor. Just as happy on DC as well as AC. Ever used a 'router speed control' with one? The speed control makes AC into a pulsed DC.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Universal (Series) motor run on either AC or DC. many have claimed smoother/quieter operation on DC.
    Some years ago there was a T.M. manuf that used a universal motor using a bridge in conjunction with the Motorola TDA1085 IC designed for washing machine motors.
    It has built in tach control.
    Many of the cheap router controller are Triac control so still AC.
    Max.
     
    Last edited: Mar 20, 2014
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