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DRV8301-HC-C2-KIT : What is the worst time delay of the start up phase by using one of your sensorless strategy ?

frank philippot
Prodigy 75 points

DRV8301-HC-C2-KIT seems to be made only for sensorless BLDC. Are there any inputs for hall sensor signals to drive a sensored BLDC ?

I fear that the start up response time of a sensorless BLDC is not compliant with my requirements. What the worst time delay of the starting up by applying one of your sensorless strategy compared to a sensored control ?

  • 0
    Intellectual 720 points

    Frank,

    J4 and J10 on the board "DRV8031-KIT" can be used to connect the sensor, e.g. Hall-Sensor.

    I am not sure, what you mean by "start up response time". Whether it is sensored or not, you can change the parameters of PID-Control to make the loop quicker or smother!

    So sensorless BLDC at "DRV8301-KIT" is also "closed loop". With sensor input you just have another of estimating/detecting the rotor position.

    Correct me, if I misunderstood it.

    Long

  • 0 in reply to Long Wang
    Prodigy 75 points

    I know from RC controller that the startup sequence of a sensorless BLDC is sometimes erratic. It looks like that the motor is misfired (turning reverse then forward). From my understanding the position of the rotor is unknown at the beginning of the startup phase. The first command may induced a reverse rotation depending of he position of the rotor versus to the energized coils. This misfired command may induce a delay of the response time. I suppose that the command of the BLDC during the first turns is blind because BEMF is too small. So I was not thinking about PID tuning which is another topic.

    I'm not an expert about this subject. I'd be interested about any document explaining the startup strategy used by your algorithm.

  • 0 in reply to frank philippot
    Intellectual 720 points

    Now I understand your question better.

    For sensorless start up, I only knew, a resolver can be used to sense the start up position. In this case, start up is not blind.

    If  start up is blind, I will drive the motor with low frequency and then increase the frequency to speed up the motor, until I can measure EMF signal.

    If PWM signals are used, it means changing the PMW frequency.

    Yes, at the beginning of the low frequency the drive signal can tune the motor in reverse direction, I have no ideas how to garantee the right spin direction by blind start up.

    Long