I’d like to know more about the breaking and regenerative breaking behavior of Orel20 and Sapog firmware. We have eight Orel20 mounted on a fixed wing aircraft in open loop control mode. The flight velocity and small propellers requiresr to spin the engine at a fast rate to produce thrust, therefor it is quite easy for the propeller to enter windmilling state, especially in descent.
Three pictures are attached:
-Current and voltage measurement by Orel20
-Air velocity, calculated thrust and engine RPM
-ADC0/1: current measurements by power boards at the battery level
We have 2 batteries powering each 4 engines.
So far we identify one safe state:
-The propeller is producing negative thrust but the pilot keeps some control on the engine RPM and no power is produced (visible shortly at time=330s in the images). How does sapog manages the engine control in this case?
Lately we found a weird behavior:
-If the pilot sets throttle stick at 0%, high current spicks are returned to the power bus (shortly 14A!). Propellers are stopped shortly with a loud mechanical sound before being in what appears to be free-wheeling mode, despite the 0rpm measured by the ESC. And this is can be a cyclic behavior until the pilot throttles up again.
After reading both Orel20 and Sapog doc, I’m unable to explain these behaviors so I’d like to understand better:
-how does Sapog applies regenerative breaking and what is an “active free-wheeling”?
-as you can see in the pictures, measured current from Sapog doesn’t go negative and I don’t think this is only due to filtering. Is it possible to obtain the negative values as well (would be much useful for identification)?
-would it be possible to remove this regenerative breaking behavior or to control it better!(it is not really funny to hear that noise in flight) ?
-I understood that Sapog does not have breaking behavior (not regenerative) is that correct?
Thank you for help!