Hi,
Our setup is DRV8301 eval kit, F28069M, 42V supply, PMSM motor. Phase to Phase peak Kt = 32 oz-in/A. Ke = 23 Vpeak/kRPM. Encoder sensored control. flag_enableForceAngle = true.
Question 1: We've found that when motor is holding zero, or idle position, - it seems to max out at approx 3.8A current draw (this was verified with a scope). What is triggering this limit?
The graphs below show 5 cases of where the holding torque is overcome (and the motor shaft forced out of position for approx 3 seconds before releasing).
I've seen several threads on this behaviour. But couldn't get to the source of our problem here. Before digging too deeply, could you point us in the right direction.
Motor max amps is set to 15.0. And we have seen that during position moves with high accel, the currents measured are greater than the apparent 3.8A holding limit (measured and verified on scope at values over 5.5Amps)
Question 2: Can we expect the torque figures (shown in Nm below) to be valid during these holding torque periods? I've included some of our motor data above. The torque plot below shows several cases where values range between roughly 3.2 to 3.5 at steady state currents. We have also seen bigger discrepancies than this in other testing trials.
Thanks in advance!