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LAUNCHXL-F28069M: Fixing a Motorware issue for accelerating/decelerating a centrifugal blower

Part Number: LAUNCHXL-F28069M
Other Parts Discussed in Thread: MOTORWARE, , BOOSTXL-DRV8305EVM, DRV8305

Hi all,

A bit of background of my system: I've got the LAUNCHXL-F28069M connected to a BOOSTXL-DRV8305EVM driving the BLDC motor of a centrifugal blower (sensorless). I've had it up and running via Motorware for some time and run my own controller that works with the Instaspin FOC software based upon Lab11a of the tutorials: I regulate pressure and use a speed reference to input into the bog-standard PI cascaded control loops of speed and current. The disturbance to the pressure is very dynamic and requires the BLDC motor to constantly accelerate and decelerate between high and low speeds (I say low instead of zero because it's a sensorless drive, so needs to be spinning).

The issue that I have comes with figuring out the top-end acceleration profiles possible. The system can handle the maximum acceleration profiles I'm after from low to high speed. The problem is when it decelerates from high to low speed: the drive decelerates the motor a bit but then fails. The "nFault D1" LED lights up on the BOOSTXL-DRV8305EVM and the motor does spin, although it's definitely not smooth and it gives out a very high-pitched ringing sound. I don't like it being in this state for long so I set Flag_Run_Identify false and restart the system - upon a new compile it works fine, until a large deceleration trips it up again. My gut is telling me that the sensorless controller loses track of its position during that deceleration, rather than it being a current overload - it doesn't seem to ever reach peak under the acceleration I'm asking of it. I don't get any error warning on the UserErrorCode handle, either.

My work-around is to decrease the maximum acceleration profile, but this will clearly have a knock-on effect on the performance of my control system. If it just requires the deceleration to be reduced, rather than the acceleration, then that would be better (I think I spotted a way of having different acceleration/deceleration profiles in the forum).

There's not really a question involved in this because I'm just after a bit of feedback to see where my issue lies, and if there's some kind of resolution so that I can get the most out of my device.

All the best,

Jon

  • Jon, Page 28 of the DRV8305 datasheet has details on the conditions at which Fault pin will be activated. Would recommend to identify the exact reported fault for diagnosing.

    Also monitor DC bus if it overshoots during deceleration.

  • Hi Navaneeth,

    Sorry for the delay - I posted just before taking annual leave, which was a bit daft in hindsight.

    Thank you for the suggestion. I've been so caught up in looking through the InstaSpin labs and documentation that I totally forgot to check the documentation for the drive itself, which looks way more useful for this. I'll do some testing, get the fault to occur and then read the SPI (provided it triggers).

    Jon