How does Open Loop work

[JoshS]

Here's my setup:

• Nucleo G431RB
• IHM08M1 (Setup for 3 phase current sensing)
• MCSDK v6.3
• Motor is Annaheim Automation BLWS234D-36V-4000 (BLDC motor - Delta winding- 2 pole pairs)

I've tried many different settings to try to get my motor to spin. Currently trying to go to the most basic setup and just input current in open loop mode but it seems the behavior is not what I would expect. I'm setting the speed ramp to ramp up to some speed and I expected that this would result in a cycle of PWM outputs at the given speed and at a duty cycle proportional to my voltage refence. Instead it appears to try pushing some current for a couple seconds then just gives up. I'm not getting any faults and there are no current measurements showing up in the Id or Iq boxes. I would expect those values to come to some steady state. I feel like I'm missing something here.

[Gael A]

Hello JoshS,

Have you taken a look at the Open Loop Documentation ? You can find it in WorkBench by clicking on About -> Documentations -> Documentation -> In the newly opened browser window, click on User Manual -> Open Loop description and usage.

I recommend starting with Open Loop Voltage mode then switching to Current Mode once you are sure voltage generation is correct.

 

Also, have you profiled your motor ?

[JoshS]

After some more testing I think I found the issue. It seems that selecting both the Open Mode and Profiler options breaks the generated code. I can build with Open Loop just fine and same with Profiler. However, if I select both nothing seems to work correctly. If this is correct behavior I suggest adding a warning in MC Workbench or disabling selection of both.

[Gael A]

Hello JoshS,

I am glad you found a way to make things running. Also, thank you for your feedback, we will make sure to investigate this matter.

[ASA]

Hello @JoshS ,

As you suggested, from release MCSDK 6.3.1, selecting Open loop feature and the Motor control Profiler is not allowed anymore.

Kind Regards.