• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 82 subscribers
  • Views 490 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TIDM-1000: Load regulation on TIDM-1000 when connecting to a motor

Andre Costa
Prodigy 40 points

Part Number: TIDM-1000

Tool/software:

I have been working with the TIDM-1000 3 phase vienna rectifier evaluation board, most recently in build 3 as per the reference design, with a C2000 microcontroller card. When connecting to a resistive load, the rectifier works fine and I can reliably control the output to a set voltage. When I have tried to connect an ECM motor to the rectifier output, targeting a 380 V output with a 208 V input I see the rectifier fail to reliably maintain the output voltage at the setpoint. It instead ramps to 500 V, which is well beyond the setpoint. I have found that when connecting a 500 ohm load in parallel with the motor, the rectifier can regulate its output just fine, and the motor is able to run. Is there any known way to improve the load regulation on this design for use with an ECM or similar application?

  • 0
    TI__Expert 6020 points

    Hi Andre, 

    Check the motor specs you are connecting. unfrotunately, I am not sure about your specifc application. 

    Let me know if you have any queires related to the hardware or software aspects of TIDM1000 design. 

    Thanks & Regards,

    Uttam

  • 0 in reply to Uttam Reddy Pailla
    Prodigy 40 points

    Hi Uttam,

    Upon further investigation, it seems that the problem we were having was when the motor was unloaded, it was drawing very low current. It seems the control system does not handle low currents well (in the 10 to 40 mA range), as when we were operating at this point the voltage exceeded the set point in build 3. Is there a known lower limit to the current that the output can supply before the control cannot regulate the output properly?

    Also, is there any way to account for loads that are not always on and constant in nature? We found that if we let the motor turn on with the 300 V that the rectifier supplies before turning on the control card by turning on our AC supply and waiting before activating the control card, it will work fine when the control card is generating a 370 V output. If we turn on our supply to the rectifier at the same time that we activate the control card, since the motor is starting up while the control card is active we see the issue of the output voltage ramping above the setpoint (presumably because the current being drawn by the motor at startup is too low). What would happen if the rectifier had no load on the output, does the control system account for that as well?

  • 0 in reply to Uttam Reddy Pailla
    Prodigy 40 points

    I found a related forum posting from some years ago, in which the TI expert seemed to imply that the TIDM-1000 does not control the output voltage at low currents well, but it seemed there was never a definitive answer to the thread.

    TMS320F28379D: TIDM 1000 vienna regulation without load - C2000 microcontrollers forum - C2000Tm︎ microcontrollers - TI E2E support forums

  • 0 in reply to Andre Costa
    TI__Expert 6020 points

    As mentioned in the thread, at that design time no-load/light load condition is not considered