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CCS/TMDSSOLARUINVKIT: connection loss after plugging-in AC source

Mauricio Neiff
Prodigy 60 points

Part Number: TMDSSOLARUINVKIT

Tool/software: Code Composer Studio

Hello everyone, I'm putting my hands on the TMDSSOLARUINVKIT and I've successfully tested the flyback stage, now I'm trying to test the operation on-grid but I'm having some problems.

I'm following the User's Guide (Literature Number: TIDU405B), trying to run the test 6.3.2 Full PV Inverter System Check without MPPT (BUILD=3)

I have setted up all the configuration variables:

#define INCR_BUILD 3
#define GRID_CONNECT 1
#define MPPT 0
#define GRID_FREQ 50

(NOTE: the mains here has 220VRMS and 50Hz)

First I connected the external power supplies for primary and secondary sides, rebuild all and clicked on debug. Loaded the window of variables, and then proceeded with the steps indicated in the guide:

  1. Run the project by clicking on (PLAY ICON).
  2. In the watch view, check the value of Gui_Vrms and Gui_Vpv to display the input voltage at the flyback stage and the AC voltage source rms value at the micro inverter output.
  3. Turn the AC source on, and ensure the frequency is 60 Hz and rms voltage is 110.
  4. Gui_Vrms will show around 110 V. If the resistive load is used, the power drawn from the DC power supply will be around 120 W.
  5. Turn on the DC power supply
  6. ......

As soon as I reach the step 3 and plug the inverter's output into the power outlet, the microcontroller and the PC lose connection, showing the following message in the console:

C28xx: Error: (Error -150 @ 0x0) One of the FTDI driver functions used during configuration returned a invalid status or an error. (Emulation package 8.0.27.9)
C28xx: Unable to determine target status after 20 attempts
C28xx: Failed to remove the debug state from the target before disconnecting. There may still be breakpoint op-codes embedded in program memory. It is recommended that you reset the emulator before you connect and reload your program before you continue debugging

The variable windows dissapaears and I stop the test.

I have checked that the live wire of the power outlet would be connected with the live wire pin of the board, as well as for the neutral wire. The external bias power supplies are floating. I connected a resistive load of 1kohms as the local load and I checked the jumpers for interconnecting the DC/DC stage with the inverter stage.

I would really appreciate any suggestion, may be I'm missing something since the user's guide seems to be made for 110V mains tests.

I have thought of trying first connecting the AC plug, and then the DC external biases. I guess may be some disturbance in the AC grid caused by the connection of the inverter with the grid affects the external power supply and it mekes it lose connection? But I really don't want it to lose connection in mid-test since I'm afraid if some powerMOS gets stucked in a turned-on state and burns something.

 

Waiting for your replies. Thanks for your time!

Mauricio

  • 0
    TI__Mastermind 43730 points
    1. Can you wind the USB wire on a ferrite bead to minimize noise
    2. Can you tests with a AC source instead of the real grid socket? that ways you can soft start the AC voltage to see where the issue is coming from ?
    3. Also, I am not sure if the bas supplies that you use they are three pronged or two pronged? The one you are supposed to use are two pronged ones
  • 0 in reply to Manish Bhardwaj
    Prodigy 60 points
    Hi Manish, thanks for your answer.

    1. I just tried it winding the USB cord but the problem stills the same.
    2. We don't have an AC source.
    3. I use two pronged ones, they came in the box with the development kit.

    Additional information: All the LEDs on the board remain ok, so I think the power supplies are still delivering their power without problem (but there might be some transient noise I can't detect...)
    Also, I'm using a desktop PC.

    I would like to mention that today, I made it to the stage of injection to the grid BUT connection got lost in mid-test. What I did was replacing the PC wire for a two-pronged one and it didn't lose connection at the first try (YAY!).

    So, I moved on with the steps of the guide and set the relay on and started injection. I heard the "click" of the relay's contact and then a buzzing sound that I didn't like much but I knew switching converters have ... so I didn't care much. Then, I checked my scope and I noticed the current drawn/feed from the grid turned weird shaped (it was a sine-like wave due the local resistive load) So I stopped the inverter with Gui_InvStop and prepared to retry again with more attention to the readings on my scope. I set up Gui_InvStart to 1 and it started "injection" (buzzing sound again) but this time it lost connection two seconds after that... buzzing sound, scope reading an ugly current from grid, and a board out of control... I freaked out and turned off all sources...

    I'm using an isolated current probe and battery-powered Fluke scope.

    I think the problem is some noise in the grid when this board is plugged in or when it's doing something and I'm really feeling stressed to continue trying using this without anything blowing up. This board is REALLY expensive and I would hate not making it work before it explodes!

    Any suggestion? Someone suggested me to use a laptop but I would like more opinions about this matter?

    Thanks again, and sorry for the long post...

    Mauricio.
  • 0 in reply to Mauricio Neiff
    TI__Mastermind 43730 points
    1. Mauricio, the board is targeted for HV trained individuals, if you have not recieved training or are unfamiliar with you should not be using it.

    2. In your tests , which build level are you at , and is DC-DC stage also enabled? The reason why ask this is if you are seeing un-familiar behavior one needs to resolve the variables and it may be better to use another build level.

    3. Given, something weird has happened, please go back to build level 1 and 2 and ensure the power stage is still healthy

    4. We only tested this design with AC source, it is not meant to be a product and connect to grid directly as it is not tested, nor complies with grid connection requirements.