I use the Odrive S1 to test custom motors i make, i’m currently working on a 4KV motor, quite big and powerfull.
The issue is that with the same power supply set to 24 V and 10A the motor runs at a maximum of 1.2 rps when controlled by a ESC (sensorless and with no way to configure anything) and when controlled by the Odrive i can reach at maximum .9 rps.
Is that expected behavior or might i be configuring it wrong? I had to calculate the specs of the motor myself so i tried playing around with the KV when configuring the motor, but to no efect, the maximum is always 0.9rps
Also its the first time i have to configure a motor as gimbal! The phase resistance is 1.5ohm, i dont know if that might be related
Hi! Yes, the S1 has a 78% modulation depth limit, this is effectively the maximum utilizable percentage of DC bus voltage. This limit will be lifted in a future firmware version.
However, the gimbal mode may be also exacerbating this. You can try running in the HIGH_CURRENT/PMSM_CURRENT_CONTROL mode, or you can enable the wL_FF_enable feedforward term to help compensate for motor inductance. The bEMF_FF_enable term may also work, but it relies on an accurate torque_constant value (which is 8.27/kv, so it relies on an accurate KV value). Happy to give instructions for characterizing the kv experimentally!
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Thanks a lot for all the information, i’ll test all of it!
I’d really appreciate those instructions if you wouldnt mind!
For now i’m calculating kv like this: i have a comercial motor conected to an odrive spining at a set speed. The comercial motor is attached to the rotor of the tested motor. And with a multimeter i’m reading the voltage generated across two of the phases of the tested motor
The “proper” way here is with an oscilloscope, Oskar showed the methodology here: Project HoverArm - #2 by madcowswe
Very cool post, thanks! I’ll look into getting an osciloscope to test it. Would you expect the results from both methods to stray a lot from each other?
