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Thread: 300A VESC in the works, feature suggestions wanted

  1. #1
    TechAUmNu's Avatar
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    I am starting work on designing a 300A VESC. Estimated Price as 3rd Aug 2017: £350

    So far I have chosen to use OptiMOS fets and associated discrete gate drivers
    FETs: FDBL86361_F085
    Gate Drivers: UCC27211A-Q1

    The first version will have:
    • 6 Fets per phase leg (36 total)
    • 6 Gate drivers per phase (18 total)
    • CNC machined aluminium heatsink with NO fan
    • STM32f405 Cortex M4F
    • Nichicon PW(M) capacitors
    • TVS diodes on power rails
    • 16s LiPo maximum (Rating at 80v for most components gives 19s*4.2v = 79.8v so this is a safety margin however the TVS diodes need to have room to start conducting)
    • 300A continuous
    • 1200A burst
    • Axial connectors (Everything inline to make them stackable)
    • All standard VESC features (CAN, SPI, Encoder/Hall support)
    • Lots of free space around mounting points for shock mounts
    • 60W nominal power dissipation at 300A (Continuous for 5min before performance degradation)
    • 130W nominal power dissipation at 400A (Continuous for 2min before performance degradation)


    Progress so far:
    • Power stage components chosen
    • Power stage schematic complete
    • Logic side schematic complete
    • Power dissipation calculations complete
    • Power supply selection complete
    • Buck converter design complete
    • Switched gate drivers to UCC27211A-Q1
    • power stage rework complete
    • Switched MOSFETS to FDBL86361_F085 to reduce cost and power dissipation
    • Power board layout complete
    • Power board ordering complete
    • Logic board layout complete
    • Logic board ordering complete
    • Power board testing in progress...



    Is there any special features that would be particularly useful to roboteers?
    Last edited by TechAUmNu; 3rd August 2017 at 23:00.

  2. #2
    typhoon_driver's Avatar
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    Features - cost less than a tenner. You'll be very popular

  3. #3
    overkill's Avatar
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    A potted case is a REALLY bad idea! I tried that on a number of IFI Victors a few years ago and they all eventually died. It was traced back to the potting resin expanding at a different rate to the PCB and causing solder joints to crack. A thin conformal coating is a better bet. Room to add our own shock mounts is a good idea.

  4. #4
    TechAUmNu's Avatar
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    Quote Originally Posted by overkill View Post
    A potted case is a REALLY bad idea! I tried that on a number of IFI Victors a few years ago and they all eventually died. It was traced back to the potting resin expanding at a different rate to the PCB and causing solder joints to crack. A thin conformal coating is a better bet. Room to add our own shock mounts is a good idea.
    Good to know! Its probably best to not have any coating then to make it easier to replace parts.

    As for pricing I don't want it to be over £300 current BOM is ~£120 + board.

  5. #5
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    There's a couple of us trying to build 300A ESCs now.

    Personally I'm not a fan of directFETs, can't inspect joints, package is unique to Infineon and they seem to discontinue them quickly. HSOF packages seem much better to me, it's what they use in the Vex BB controllers.

  6. #6
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    Not sure on the integrated shock mounts. Prefer some flexibility on mounting e.g. mount into a shock mounted electronics box

    I'm looking to drive 8019 Neumotors - http://neumotors.com/80xx-series-electric-motors/

  7. #7
    TechAUmNu's Avatar
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    Quote Originally Posted by shakesc View Post
    Not sure on the integrated shock mounts. Prefer some flexibility on mounting e.g. mount into a shock mounted electronics box

    I'm looking to drive 8019 Neumotors - http://neumotors.com/80xx-series-electric-motors/
    I will make the mounting points on the board with plenty of room around them instead, then it gives people mounting flexibility.

    So about 350A peak on those motors, I might end up making another board with 6 or 8 fets per phase if there is demand. It really bumps the price up though.

  8. #8
    TechAUmNu's Avatar
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    Quote Originally Posted by Pinski1 View Post
    There's a couple of us trying to build 300A ESCs now.

    Personally I'm not a fan of directFETs, can't inspect joints, package is unique to Infineon and they seem to discontinue them quickly. HSOF packages seem much better to me, it's what they use in the Vex BB controllers.
    I was thinking that too, only real reason I was going with them was for the ability to stick a heatsink directly onto them, but looking at the HSOF I am going to use this one instead.
    http://www.mouser.com/ds/2/196/Infin...-en-767648.pdf
    Has almost half the on resistance and bumps the current rating way up for a very small price increase.

    Thanks!

  9. #9
    TechAUmNu's Avatar
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    Would people prefer it to be

    A) Smaller with no 5v Dc-DC. i.e. OPTO
    B) Larger with integrated 5v Dc-Dc about 2A (also makes it £10-20 more expensive)

    I think its best to be OPTO since people will likely already have a 5v dc-dc and if they don't they can easily add one.

  10. #10
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    My vote would be OPTO

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