We are using a Zubax Myxa A2Z ESC (AmpDrive AD0505A/B, Telega V0) in a regenerative braking configuration. The ESC is operating in RPM control mode (esc_rcm = 1). Our setup involves one motor connected to the Myxa ESC, which is being driven by another motor acting as an “engine.” The goal is to maintain a constant RPM while maximizing regenerative power extraction.
Currently, the regenerative performance appears to be limited by the maximum braking current, which in v0 appears to be hard coded to be a fraction of the rated phase current amplitude.
In the Kucher app, the max_current is set to 200 A (maximum allowed) However, the phase current (I_Q) saturates around 20 A
This suggests an internal limitation at approximately 10% of max_current.
With this configuration, we are able to extract approximately 300 W of power, but our target is 1200 W or as high as practically achievable.
Now, we are wondering if it is possible to increase the maximum allowable phase current (I_Q) or increase the maximum braking current fraction in Telega v0 for the Myxa ESC? If so, could you let us know which parameters control this limit?
Sensorless FOC drives tend to lose stability at high braking currents so there is a hard-coded 10% limit in v0. This limit is adjustable in Telega v1 so you might want to try that. Alternatively, we could craft a special build of v0 for you but it might take some time to get around to that.
Thanks for the response, Pavel.
Sensorless FOC drives tend to lose stability at high braking currents so there is a hard-coded 10% limit in v0.
I assume the underlying stability concern is tied to sensorless FOC operation, so this issue may still exist in v1, even though the braking-current limit is adjustable. Is that correct?
This limit is adjustable in Telega v1 so you might want to try that
I have updated one ESC to v1 and will test with it to see whether the adjustable limit helps us reach the desired regenerative power level.
Alternatively, we could craft a special build of v0 for you but it might take some time to get around to that.
At the moment, however, the special v0 build is our preferred option. We are using a Simulink-to-PX4 workflow, and I am not yet sure whether Cyphal is supported cleanly in that workflow. We also have other DroneCAN devices, including power management units and servos, that are currently working well with v0. Do you have an estimate of how long it would take to prepare the special v0 build?
Thanks again for your help.