AMIC120: Brushed motor control drivers or design examples?

Viktorija Cecil

Mastermind 18291 points

Part Number: AMIC120
Other Parts Discussed in Thread: CONTROLSUITE

Team,

My customer is working on AMIC120 based EtherCAT+motor control design, and has a few questions, I hope you can answer:

Are there any drivers or design examples you’d recommend considering if the application will be 24V brushed DC motor only? (customer is already aware of BLDC ref design). Requirements for the application would be:

Two separate RS-422 Quadrature encoder feedbacks (would be run into the quadrature encoder conditioners of the Sitara)
Closed loop position or velocity control with a minimum servo cycle rate of 4kHz. PWM switching for the current control loop should be 20kHz or faster.
Motor current feedback (minimum sampling rate 10kHz, 20 kHz preferred)
The DC bus will be 24VDC and 1A will be sufficient.

Are there performance benchmarks for the 3 phase motor design example with Field Oriented Control on the AM437x? It looks like the design example runs 33kHz servo cycle rates. What kind of servo cycle rates could be achieved running this on an AMIC120 at 300MHz?

The brushed DC motor wouldn’t require FOC / commutation calculations, so this should significantly reduce the processing requirements

Thanks

Viktorija

over 6 years ago

0 Viktorija Cecil over 6 years ago

TI__Mastermind 18291 points

Team, can you please look into these questions.

0 Jason Reeder over 6 years ago in reply to Viktorija Cecil

TI__Genius 10435 points

Viktorija,

Unfortunately, we do not have any examples for brushed DC motors on AMIC120. The C2000 team was asked a similar question here (https://e2e.ti.com/support/microcontrollers/c2000/f/171/p/281802/984585#984585) and they pointed to the DRV88xx and DRV84xx motor drives meant for this purpose and also pointed to an example in their controlSUITE software package (DRV8412-C2-KIT). It may be the case that the control portion of that demo could be ported to AMIC120.

The benchmarks for the 3 phase motor design example on AM437x (www.ti.com/.../TIDEP0025) can be found here: http://www.ti.com/lit/pdf/tidu701

These benchmarks were run with the AM437x at 600MHz and the timing for each piece of the control loop can be found in Table 1. The determination in the benchmark document was that the AM437x at 600MHz should be able to close the current loop at a rate of 48kHz (including an added 25% headroom for good measure). Assuming that that each piece does not simply double when the main processor runs at 300 MHz (ADC acquisition will remain the same for instance), then the device should have no problem closing a similar loop at a 20kHz rate.

Jason Reeder

0 Viktorija Cecil over 6 years ago in reply to Jason Reeder

TI__Mastermind 18291 points

Thanks, Jason. I will let you know if they have follow up questions.

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AMIC120: Brushed motor control drivers or design examples?