Hello,
I am running a motor with encoder using LaunchPad TMS320F28069M with BoosterPack DRV8305. As long as the motor spins not too fast, everything is working so far. However, when I increase speed, at some point the encoder starts to miss counts. As a result the motor gets slower or even stops while there is maximum current applied (I guess because the error between perceived and actual electrical angle gets too high).
First I thought my encoder was just bad, but after switching to a different encoder, I still see the same behaviour and it seems to always occur at the same encoder line frequency:
1. Encoder: 20000 lines
Already starts to miss a few counts at lower speed but significantly increasing at 900 rpm.
2. Encoder: 5000 lines
Now the motor runs up to 3600 rpm but then again misses lots of counts.
I noticed that with the second encoder, the maximum speed increased by the same ratio by which the encoder lines are reduced. It seems like the problem is occurring at a line frequency of 300 kHz. Both encoders should be able to deal with much higher speed according to the datasheets.
Is there a limitation in the hard- or software that explains this? If yes, is it a fixed limit or is it dependent on some settings?
Best, Felix