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CRD200DA12E Startup

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djsubert
djsubert Contributor Level 1
edited April 28 in General

Wolfspeed forum,

I am looking for tips/tricks on working with the previous generation CRD200DA12E. We utilize the CRD200DA12E to create a 3ph sin wave to test a set of current sensors (one for each phase). The DC link is 45VDC & we are utilizing 0.8ohm resistive loads. To interface with the gate drivers generate the sin wave, we created a circuit board with RS485 transmitters and an Arduino. Our base switching frequency is 20khz. Cooling is handled by a stand-alone WEG chiller from one of our test cells.

With this configuration, we are able to successfully generate a clean 3ph sin wave for several minutes at several current levels. After a few minutes, the sin wave becomes distorted. We observe DC offsets & sharp peaks in the 3ph current waveforms.

For troubleshooting, we have looked at the usual suspects without positive results:

  1. Fault pins from the gate drive boards
  2. Noise impacting the gate drive board control signals
  3. Tried multiple sin wave frequencies & carrier frequencies
  4. (Investigating now)….double checking our 3ph arduino code is consistently generating the sin wave over time, not just at the 20khz carrier, but at the frequency of the sin wave.

Any suggestions or advice would be appreciated. Especially if there are fundamental issues with our goals/application of the CRD200DA12E.

Thanks!

David Subert

Comments

  • Forum_Moderator
    Forum_Moderator Wolfspeed Employee - Contributor Level 5
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    Thank you for your post, it has been approved and we will respond as soon as possible.

  • ChrisN
    ChrisN Wolfspeed Admin - Contributor Level 4
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    Hello David,

    For clarification, is it correct that you are talking about the CRD200DA12E discussed in your previous post? I want to confirm that we are not referring to the CRD200DA12E-XM3.

    Assuming that is the correct design, please first recognize that this design was never publicly released and therefore did not go through the same level of quality and testing checks as our publicly released designs. I believe this design was primarily distributed within research partnerships, so as mentioned in my previous post, we provide limited support for this design. Recognizing these limitations, there is nothing fundamental to the hardware that would cause the problem you described. This design has been run continuously for several hours for internal testing. I listed a few things below to consider as you try to identify the problem:

    1. Many Arduino products have a limited clock frequency (<20 MHz) compared to controllers used in most power electronics applications (>100 MHz). It's possible you are running into compute issues if you are trying to implement closed-loop control with an Arduino-based product.
    2. If your firmware relies on a counting clock, it's possible that you are having an overflow condition where you fill your counter. This would explain why you have a delay before experiencing issues.
    3. The design uses differential inputs to the gate drivers. If you are sending single-ended commands, this could explain why you are running into issues (see Section 4 of PRD-09301 for more information).
    4. It has been a long time since this design was made at Wolfspeed. I would evaluate the hardware closely to ensure that the design hasn't been modified by any colleagues previously to support past testing. If any team members have made changes to the design, this might explain the issue.

    Thanks,

    Chris N.

  • djsubert
    djsubert Contributor Level 1
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    Chris,

    Thanks so much for the feedback. To answer your question, "Yes" we are using the older CRD200DA12E which was a donation. As a university, we rely heavily on donations like this for research to control costs. Sometimes, this results in us using antiquated hardware.

    I have a lot to report since my last post. We found the Ardiuno code was incorrectly generating the sin wave.

    Since then we have:

    1. Spun up a small circuit board with RS485 transmitters to support Gate drive communication.
    2. Designed the circuit board to interface with the Launchpad controller uses on the newer "XM3" version of the inverter development board so that we can leverage the software & interface developed by wolfspeed.

    So far, this approach has solved the reported issues. We are currently generating a 3ph sin wave with an RMS current of over 100A with success!

    Thanks for the support. I'll reach out if we encounter further issues.

  • ChrisN
    ChrisN Wolfspeed Admin - Contributor Level 4
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    Hi David,

    Thanks for the update. That's great news that you identified your issue! I'm glad you got it working! I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.

    Thanks,

    Chris N.

This discussion has been closed.