Saturday, January 3, 2015

The Motor is Spinning!


I have been traveling a lot over the past month due to the holidays etc... However I have been working on this project in the few hours of spare time that I have. I just have not been able to post much. I have gone through a few revisions of my board due to some mistakes that I made but the most important part is that I have a spinning motor! I will edit this post or make some additional ones that describe how i got to this point, and attempt to explain my code and my mistakes.

Enjoy the above video that shows the motor spinning at %50 duty cycle at 25kHz carrier frequency with a 12.9 - 14.1 V high rail for the h-bridge. I will add additional videos later of higher voltages and speeds.

Update 1:

I am having some minor issues. I attempted to run the motor in the other direction. So far it has been running in the counter clockwise direction (CCW). Now when i try to run it in the clockwise direction (CW) it draws way more current. When at 100% speed it is drawing up to and over 5 amps which is beyond the range of my supply. Conversely when running at 100% speed in the CCW direction it is only drawing in the range of 1 amp. 

Here is a video showing both directions 0-50% speed. I am currently trying to come up with some solutions.


Update 2:

Sorry for the length in between updates here. After poking around online and asking the great people at /r/ECE for their input I believe the issue is due to a mis-alignment in the hall effect sensors. This is likely due to the fact that I installed them my self on a very small motor. This means that even a fraction of a degree off on the mechanical placement can result in large errors on the electrical control. Because of this I believe that In order to implement a hall sensor based control on this motor I would either need to create a jig to hold the sensors in exactly the right place, or use a back emf sensing design. Alternatively I can purchase a motor with the hall effect sensors already installed in exactly the right place. I may use the latter option for now just to continue on the same development path.

However I will not be posting on this project for some time now. I am currently travelling abroad for work and will be gone for the next few months. You can view my trip here. I did not bring any of my equipment with me and I will have to pick this back up when I return.

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