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multiple BLDC motor system with DRV8301s

Pete Owen
Prodigy 40 points
Other Parts Discussed in Thread: DRV8301, DRV8313, DRV8332

Hello,

I recently completed a test that required control of eight BLDC motors (48V/5A/10k RPM) using eight DRV8301-HC-C2-KIT eval boards running lightly modified Instaspin software and a Stellaris Launchpad to control them all over SPI.  This worked well, but required a huge box, so the next stage of the project will require a custom board or boards to minimize the package volume.  For the power drive section, I am planning to closely copy the DRV8301-HC-C2-KIT schematic with the layout modified to minimize PCB area.  

My question is how many motors could be controlled with a single F28035 controlCARD as included with the eval kits that I have?  

I suspect that all eight DRV8301/motor combinations controlled by one processor would not be possible, based on reading the spry135.pdf whitepaper, which seemed to indicate not a lot of extra headroom running two motors, but that app note is for FOC control, which I imagine is more processor intensive than the Instaspin trapezoidal drive?  Also I don't need the PFC described in that app note.  

Would there be a better processor choice?  

Thanks for any help you can provide.

Pete

  • 0
    TI__Mastermind 26065 points

    Hi Pete

    I think the limit will be subject to the controller's PWM output channels if you want to control more motors together with sensorless strategy. Usually we do one control for one motor with algorithm like instaspin or FOC, if the algorithm is simple, we can choose low end processor for better cost and small package. if only instaspin needed, MSP430 is capable also. for example, you can find our DRV8313 EVM (http://www.ti.com/tool/drv8313evm) with a value line MSP430 as the controller. But for 5A current, DRV8332 may be a choice instead of DRV8313.

    For processor choice, maybe you will get better answer on the C2000 forum.http://e2e.ti.com/support/microcontrollers/c2000/f/171.aspx

    Thanks,

    Regards,

    Wilson Zuo

    Motor Application Team

  • 0 in reply to Wilson Zuo
    Prodigy 40 points

    Hi Wilson,

    Thanks for the quick reply.  I will look into the DRV8332/MSP430 combination, as that seems like it would be very compact.  If I have the motor running acceptably using the  DRV8301-HC-C2-KIT, would it be an easy task to get the motor running with the DRV8332/MSP430?  I don't see the code that runs the project in the DRV8313 EVM download, I guess it's contained in the 8313 library?  I do not have time for extensive software development, so hopefully this would be fairly simple to set up.

    Can you give me an idea as to what size heatsink would be needed for 6A operation with the DRV8332 at room temperature?

    Thanks,

    Pete

  • 0 in reply to Pete Owen
    TI__Mastermind 26065 points

    Hi Pete

    if your application function is simple, you can use the solution just the same as our EVM. But any change will need maybe extensive coding effort.

    C2K is much stronger than the 430MCU on DRV8313 EVM. I think only the basic sensorless driving algorithm using instaspin can be applied to the value line 430MCU.

    About the heatsink, you can try bigger one first. There is one FYI in DRV8432's EVM http://www.ti.com/tool/drv8432evm. You can find the heatsink dimention in the User Guide.

    Thanks.

    Wilson