MCSDK 6.4.1. FOC with hall sensor start up issues

[BWI]

Hello,

I did a custom design based on EVLSPIN32G4-ACT, schematic is basically the same apart from board shape and connectors.

The hardware is working in general, I successfully got my BLDC motor without an attached load spinning using sensor less speed feedback.

The application is the drive unit for an radial fan. After attaching the fan impeller to the motor shaft the before working setup would not spin up anymore.

I got speed feedback failures, then I raised the start up current until I got over current events. All not working.

The motor also features integrated hall sensors, so I decided to switch to those. The mechanical speed returns sane values inside motor pilot software, so I assume them working.

Using the hall sensor, the motor is trying to spin up in the wrong direction finally failing with an speed feedback error.

How ever, if I give the motor a push in the correct direction, it will spin up and then be driven to the max. application speed.  At this point new speed set values are ignored by the firmware until the motor is stopped again.

Summary:

- the custom board seems to be working in general

- the motor looks to be connected and setup so it should be working

- after attaching a load, no spin up in sensor less FOC mode (PLL + Cordic)

- hall sensor setting spins up motor in wrong direction, when pushed by hand to correct direction fast spin up to max speed and new set values are ignored until stopped

Could you give a hint, how to troubleshoot this?

Thanks and best regards

Benjamin

[GMA]

Hello @BWI,

If with load, the motor is not able to spin, it could mean that your selected board does not provide enough power at the beginning. Does Sensor Less RevUp table uses the maximum allowed current?

You can also dynamically tune the current target parameter through the Motor Pilot tool in the Rev-up tab.

[BWI]

Hello @GMA ,

as I said, I already tried your suggested adjustments in the rev up table until I got overcurrent events.

The driver board is very well capable to supply enough power to spin up the motor and to rev up to taget speed as I also mentioned.

My chosen hall sensor approach also does not offer any settings regarding start up current, as this is only available  for the sensor less speed sensing option.

My questions:

- why does the motor try to spin up in the wrong direction using hall speed sensing option? This issue persist for both directions

- when motor is spinning up to full speed after getting a push in the correct direction, why are new set values ignored, the firmware does not indicate any errors. The motor pilot software also correctly reports changing set values, how ever they do not get applied.

Where do I start to look?

[BWI]

Hello @GMA ,

I was playing around with the rev up parameters until I managed to get the motor spinning with the load in sensor less mode.

The hall sensor feedback seems to not work properly because it is somehow interfering with my setup using TIM8 Ch1 as PWM input to control the speed.

How ever the max. speed is limited to about 30% of the max application speed the motor is rated for (3k RPM). Even I give  a higher set value there is the ceiling at ca. 1150 RPM. The power draw in this state is about 15W@12V and far away from the current limit of 4A. What is limiting the speed?

[GMA]

Hello @BWI,

The maximum speed might be limited by the Max Modulation index value if it is not computed close to 100%.

If applicable, you can improve it by reducing the PWM frequency.