System:
3-phase bldc in delta configuration
drv8332 w/ OC_ADJ resistor at 19k
pwm at 160kHz(testing at 40k, 60k, 80k has not had any noticeable effect)
Behavior:
It would seem my system operates properly up until about 18% duty cycle at which point motor faults start to occur. In my attempt to understand the faults, I ignore them and have the microntroller reset the driver and attempt to continue operation. This allows me to run the driver up to about 35% duty cycle with significant inefficiencies but still increasing speed. I figured this would be caused by a latching shutdown from overcurrenting; however, scoping the current on the lines never showed current exceeding 4A. What was observed was an interesting asymptotic behavior of current which I would speculate is from saturation of the inductors. But the inductors were tested to maintain linear current up to 20A. attached are some graphs of the output from scoping, any observations or comments would be appreciated in trying to figure out what is wrong.
Figure 1. The current of each motor line right before entering the motor at 0.5A / div while running at 10% DC.
Figure 2. The current of each motor line right before entering the motor taken at 2A / div while running at 20% DC.