Hi all,
I need to control the TORQUE of a 50W 24V BLDC motor. Is it possible with the Odrive to have a SPEEDlimit during torque control? So the engine is not speeding up to maximum speed when no load is applied.
Thanks,
Steven
Yes! This is enabled by default, actually. See here: Controller — ODrive Documentation 0.6.11 documentation
Note that proper speed limiting in torque mode requires tuning the vel_gain in velocity mode.
Thank you Solomon, that is what I need.
Is there an encoder needed or is this also sensorless possible?
Sensorless is supported, under certain operating conditions – namely a minimum speed limitation. Could you share a bit more as to your application/requirements?
Thanks. A minimum speed limit could be ok. I would use it for a small winding application with 2 winders (24V bldc engines 1000rpm). When switching between winders, there is for start no load on the second winder, this would drive this engine to maximum speed. But the RPM can not go higher then the speed-limit or it would break the material. There are 2 variables available on PLC CANbus: Torque and speed-limit. The given speed-limit is variable and calculated on the current line-speed.
Should work fine in sensorless! I’d maybe recommend instead running in velocity mode with a torque limit, which will help prevent it from falling below minimal speed. Which specific motor are you considering? I’d be happy to recommend a starting place for the sensorless parameters.
Thanks Solomon, running in velocity mode with torque limits could work. For now I am testing the 42BLF02 4000rpm with a gear ratio 4:1 and encoder. But a better option would be the WK8115 24V 5,8A 954rpm 21pairs (no encoder) so I do not need a gear ratio. The Odrive micro has 100W limit, do I better order the Odrive S1?
On the side, is the communication doable with canbus between the Odrive and a PLC?
The WK8115 should be fine. No issues using it with the Micro as long as the slightly lower torque limit isn’t an issue – you’d get about 0.66Nm continuous, 1.3Nm peak. 42BLF02 is usually around 0.125 Nm continuous, 4:1 gear ratio is 0.125*4 = 0.5Nm, so I think this would work. Note you’ll get around ~800-900 RPM max at that torque (and 24V bus voltage), due to the Micro’s 78% modulation depth limit (sort of like an effective DC bus voltage multiplier) – this will be lifted in a future firmware update.
On the side, is the communication doable with canbus between the Odrive and a PLC?
As long as you can specify the PLC CAN protocol, then yes absolutely! You can see our CAN protocol here: CAN Protocol — ODrive Documentation 0.6.11 documentation
Ok, I will check the Odrive CAN protocol and then make a set up using the micro with the 8115.
Thanks for the detailed help!
No worries, let me know if there’s anything else I can do!