using DCC1120 as regen braking controller

[bugbeest]

Hey everyone! I am setting up a basic electromechanical dynamometer and was considering using a BLDC motor plus controller in braking/regen mode as the load. I wanted to ask if anyone has tried this with the DCC1120 controller, and to validate my understanding of how it/the `BLDCMotor` API would accomplish this. My understanding after reading through the API guide is that I can do the following to get "some" braking ability:

Code: Select all

...setDriveMode(DRIVE_MODE_FORCED);
...setCurrentLimit(<value based on desired torque and Kt of motor>)
...setTargetVelocity(0);
//enable the dyno, motor will provide braking torque until current limit is reached

The amount of braking torque I can achieve is (I believe) based on the torque constant of the motor I use for the load and the current limit I set, as well as the back EMF constant and my means of dumping excess voltage off the motor bus. I plan to use a crowbar circuit and a power resistor to dump the excess voltage.

Does anyone see a significant flaw in my reasoning? Many thanks!

[burley]

We built something like this internally for testing motor controllers. We used a DC motor as the load rather than a BLDC but that should work as well.

It works quite well for us, but the energies involved are fairly impressive so make sure you select a power resistor that can handle it. I believe this is the one we used but you could definitely go bigger:

https://www.tti.com/content/ttiinc/en/a ... irect=true

And if you aren't using lead acid batteries as your supply I'd really recommend an SAF2020 as well.