Hello, have got an Odrive S1 + drone motor, to act as an easily adjustable load for a model wind turbine. Ideally, I’d like to use the Odrive to set a torque and measure the power generated by the wind turbine as accurately as possible - is there any way this can be done?
Currently, when plotting the calculated brake resistor current on the GUI, the Odrive claims it’s around 0.7A, however the multimeter reads about 0.45A - does anyone know what the reasons for the discrepancy could be?
Many thanks
Robbie
Hi!
Not an issue measuring power – you can look at axis0.motor.mechanical_power and axis0.motor.electrical_power (they should be quite similar) – note the former requires an accurate kv value, so it may be off if the value specified by your motor manufacturer is incorrect (it’s frequently off by 10-20%).
ODrive will have the best estimate of brake resistor current – since it rapidly chops the current, your multimeter will likely read incorrectly. Note the brake resistor current is in terms of bus current, and is different from motor current (bus current != motor current).
Brilliant, thank you!
I’ve been plotting the electrical and mechanical power and for the most part, both are behaving as expected. my only query is that when running the motor fast and lightly loaded (above ~ 50 rev/s) the electrical and mechanical power goes negative, which doesn’t seem to make any sense. I’ve attached a graph of it spinning up to around 100 rev/s. This shouldn’t matter for our application, but any clues on why this might be happening would be appreciated 
