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Thread: Revolt Open Source Controller

              
   
   
  1. #1
    Senior Member EV_Scoot's Avatar
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    Revolt Open Source Controller

    So, who here has any experience with the Revolt Open Source controller?

    No one seems to have mentioned it.

    Here are some details: http://ecomodder.com/wiki/index.php/Open_ReVolt
    EV 500 & 1000 Amp DC Motor Controller "ReVolt" Features

    Continuous current rating of 500 or 1000 Amps.
    Any voltage input in the range of 0 to 144v.
    15.6 kHz switching frequency.
    Adjustable hardware overcurrent shutdown.
    Hardware over-current shuts down in 3-4 Ás. [1]
    RS-232 interface.
    Reprogrammable.
    High pedal lockout.
    The controller will not close the main contactor if the mosfets have failed shorted.
    Protection from many potentially destructive errors: [2]
    Control board power polarity reversed
    12V supply connected to throttle
    Full throttle at 0 RPM

    The thing that I noticed about this controller is that it ends up being rather chunky, so might not be a good idea for MC's :/
    Last edited by EV_Scoot; 28 September 2013 at 2249.

  2. #2
    Senior Member EV_Scoot's Avatar
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    Well, I looked into it a little further and it seems that the project has dried up. Oh well.

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    Member PaulWay's Avatar
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    One of the members of Canberra EV has one of those. It was fairly basic, but did the job, and if you're prepared to do the soldering yourself it was quite a bit cheaper than a regular one.

    I'm a little concerned about the low switching frequency though.

    Have fun,

    Paul

  4. #4
    Senior Member EV_Scoot's Avatar
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    Paul,

    And what would that give you? Lag?

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    Junior Member glassblower's Avatar
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    You may experience much audible noise on top of electrical noise into any surrounding electronics such as AM radio or instruments. Also can affect the harmonic currents into the motor which affects the efficiency of the motor. Probably not a big issue but worth talking to a few people in the EV auto side that have used them. When I built my 144 volt truck I contributed to these guys because I considered using this drive and believe in open source products to help out guys like us. In the end I bought a Curtis drive and have been happy with it, but like Paul said, it is clunky big and might be an issue wedging it in a bike.

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    Member PaulWay's Avatar
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    For DC, the switching frequency isn't really a problem - you're using PFM or PWM to chop the battery DC up according to how much power (i.e. amps) you want. This then gets converted[1] to DC but at a lower amperage.

    For non-induction AC and brushless DC (which are basically the same), switching does matter, as you're switching the DC from positive to negative and back, so the maximum frequency of that oscillation is limited to half your switching frequency (one positive cycle, one negative cycle). That then gets divided by the number of coils on each phase - so if there are 36 coils in total, on three phases, then you have to go through twelve oscillations to move the rotor around one revolution.

    So with a 15KHz switching rate on a 36-coil motor, you can only get (15000 / (2 * 12)) = 625 revs per second, or 37500 RPM. OK, so that doesn't sound so bad. In reality, you usually don't want to get anywhere near half the switching frequency.

    For AC induction motors, the frequency is more or less irrelevant, as the induced magnetic field in the rotor is itself rotating. It'll never be moving as fast as the stator frequency, so there's always some 'slip' - that's OK, the higher the slip the more torque. And that's about as much as I understand about AC induction motor theory.

    Hope this helps,

    Paul

    [1] I don't know how. I'm assuming big capacitors or something.

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    Quote Originally Posted by PaulWay View Post
    For DC, the switching frequency isn't really a problem - you're using PFM or PWM to chop the battery DC up according to how much power (i.e. amps) you want. This then gets converted[1] to DC but at a lower amperage.
    <>

    [1] I don't know how. I'm assuming big capacitors or something.
    Actually it is converted to higher current and uses the motor inductance. See Buck converter to understand how.

  8. #8
    Junior Member glassblower's Avatar
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    The drive EV-Scoot is talking about is a DC unit...

  9. #9
    Se˝or Member podolefsky's Avatar
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    Quote Originally Posted by PaulWay View Post
    For DC, the switching frequency isn't really a problem - you're using PFM or PWM to chop the battery DC up according to how much power (i.e. amps) you want. This then gets converted[1] to DC but at a lower amperage.

    For non-induction AC and brushless DC (which are basically the same), switching does matter, as you're switching the DC from positive to negative and back, so the maximum frequency of that oscillation is limited to half your switching frequency (one positive cycle, one negative cycle). That then gets divided by the number of coils on each phase - so if there are 36 coils in total, on three phases, then you have to go through twelve oscillations to move the rotor around one revolution.

    So with a 15KHz switching rate on a 36-coil motor, you can only get (15000 / (2 * 12)) = 625 revs per second, or 37500 RPM. OK, so that doesn't sound so bad. In reality, you usually don't want to get anywhere near half the switching frequency.

    For AC induction motors, the frequency is more or less irrelevant, as the induced magnetic field in the rotor is itself rotating. It'll never be moving as fast as the stator frequency, so there's always some 'slip' - that's OK, the higher the slip the more torque. And that's about as much as I understand about AC induction motor theory.

    Hope this helps,

    Paul

    [1] I don't know how. I'm assuming big capacitors or something.
    Actually, the signal for PMAC and AC induction are similar - 3-phase sine waves. They're both limited by the switching frequency. You're right, less than half and you can't discern the signal frequency. But it has to be a lot more than half becaus you get aliasing (you need several square waves to make anything resembling a sine wave). BLDC is a little better, but you still need to make a trapezoidal wave, so again you need the switching freq to be a lot higher than the drive signal.

    You're also right about AC induction and slip, with the rotor turning slower than the stator field. It has to be that way, since slip is what produces torque. But when it is generating (like regen braking), it's reversed. Induction motor theory is...complicated. Variable frequency controllers have to balance a number of parameters in order to run a motor efficiently.
    - Noah Podolefsky -
    The GSX-E

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