Hey y’all!
Been setting up two odrives to fight one another for the purpose of characterization (e.g. efficiency: electrical power in vs. mechanical power out). To do this I have one motor (motor1) with an odrive pro in velocity control, and another motor (motor2) with an odrive pro in torque/current control. With this setup I can set motor1 & motor2 at different constant torque & constant velocity setpoints. Motor1 will dictate the velocity, and motor1 will try to apply the target torque at that velocity (Motor1 is quite a bit larger, so motor2 can’t easily overwhelm it). I have a two 3S1P battery packs powering 1 odrive each, and I have oscilloscope readings of battery voltage & current for motor2.
When running this setup at various constant current & speed setpoints I am seeing some low-frequency ripple in the battery current & voltage (around 0.5Hz). Attached is a plot of an example at 10rad/s and 14A q_axis. I low-pass filtered the battery voltage & current data w/ a 10Hz cutoff
Any thoughts what could be causing this?
Thanks!