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settings DRV8412 EVM Kit revG

Deny Marfisi
Prodigy 80 points
Other Parts Discussed in Thread: DRV8412, CONTROLSUITE

Hi,

I bought a DRV8412 EVM Kit revG, and I have a few questions :

1) I would like to know if the emf is used to control the speed (PWM) of the motor? If yes, how was it program to work?

2) the settings (Ki, Kp, Kd and Kc) were preconfigured for light loads. I would like to know how to change does settings if I want to put a heavy load on one of the DC motor (I have no precise weight in mind yet).

3) In 'Dual DC Brushed motor', I put 20% in 'Voltage mode' and then started the motor, by clicking on 'Enable Motor', with a light load. IFdbk went up until the 'Status Fault' light turn red stopping the motor when IFdbk got to about 5A, but, on the TI website, it says that the motor should be able to support a 6A peak . So, does someone have a idea on why it stop at about 5A?

4) In the QSG-DRV8412-C2-KIT-GUI pdf file, I don't understand the significance of the 0.92A of the DC motor since we can use them at 3A continuous and have 6A peaks.

Can you help please?

Thanks

  • TI__Guru 54675 points

    Deny,

    1)  Only the DC bus voltage is measured and the speed is open-loop.  PWM is just increased for increase in speed.  Only a current loop is employed with the software released.  I have attached a document on the firmware for the brushed DC project.  This is also available in ControlSUITE (search ti.com).  

    2)  Knobs are provided to tune the parameters based on your desired loop response.  Unfortunately, I do not have a document that describes how to adjust this based on motor parameters.

    3)  It is possible you are hitting a thermal limit on the device.  Per the datasheet, the DRV8412 is rated for 2 x 3A continuous load.  Please check the status of the /OTW pin.  If this is low, then you hit a thermal limit.  You can also adjust the resistor on the OC_ADJ pin per the table in the datasheet if you think you are hitting current limit and would like to increase the limit.  

    4)  The motor provided in the kit is rated at 0.92A DC.  There is no significance beyond that.

  • in reply to Ryan Kehr
    TI__Guru 54675 points

    4401.Dual Axis BDC.pdf

    Previously forgot to attach file.  Please see attached.