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Need recommendation for BLDC motor driver for 75k RPM, 24VDC, 2A

Derek
Mastermind 9691 points

Hello, I'm working on a product where we need to drive a motor up to 75,000 RPM. Motor specs:

24VDC

2A stall current

130mA no-load current

Back-emf constant: 0.39 (V/1000 rpm)

Internal phase resistance: 700mOhms

3 hall effect sensors, 120 degree phases

Motor Interface (8 wires):

  • Phase 1/2/3
  • VDC
  • GND
  • Sensor 1/2/3

Forward only, no reverse required

Also need a speed output for monitoring by an MCU for safety

Interface can be serial or hardware, it will be controlled by an MSP430

Thanks,

Derek

  • 0
    TI__Guru 61330 points
    Derek,

    Thanks for all the details! We have devices that support up to 100V with hall input, built in buck regulator, SPI or hardware control. They all have forward and reverse. We don't have a speed output but you could estimate this using the Hall connections and your MCU.

    Looking at your back-emf constant of 0.39 V per 1kRPM, this means the back EMF at 75kRPM would be around 29V. We recommend about 20% headroom so therefore your applied voltage should be at least 35V to reach 75kRPM. With 24V available, you could probably get ((24*0.8)/0.39)*1000 = ~49kRPM.

    Not sure if you need the full 75kRPM.

    Regards,

    -Adam
  • 0 in reply to Adam Sidelsky
    Mastermind 9691 points
    Hello, what if I use hall effect sensors instead of back-emf? Can I go up to 75k RPM?
  • 0 in reply to Derek
    TI__Guru 61330 points

    Derek,

    This is about driving the motor, you need to overcome the back emf no matter how you sense the motor (hall sensors or not). in order to drive current into the motor, our voltage applied needs to be More than the back emf already generated by the spinning motor. 

    To drive the motor faster, you need enough voltage as described above.

    Regards,

    -Adam