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TIDA-00366: Floating voltage GND

Hirotaka Matsumoto
Guru 27525 points
Part Number: TIDA-00366

Hi all

Would you mind if we ask TIDA-00366?
We developed the board which is very similar with TIDA-00366 desgin.
As the different point, there is the difference IGBT module only.

The voltage conditions are follows;
VDC+ and VDC- : DC24V
Gate driver voltage : DC16V

In this case, the voltage between U_TOP_REF～W_TOP_REF and VDC- were 15V.
By these voltages, it doesn't operate normally.
It seems that there is no problem on the board.
On your reference design board, does your board operate normally??

If you have some advice, could you let us know?

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Intellectual 2890 points

    Hello Matsumoto-San, Thank you for using our reference design TIDA-00366. Could you please help us understand what is not working on the board and what is the load connected to the Inverter output? Note that the top side drivers are powered through bootstrap, and hence you need to take care of the switching sequence - turn ON all the bottom switches while starting so that bootstrap capacitor gets charged. Post which you can supply regular PWM pulses. This needs to be taken care in your software.

    regards

    Navaneeth

  • 0 in reply to Navaneeth Narayanasamy
    Guru 27525 points

    Navaneeth san

    Thank you for your reply!

    you need to take care of the switching sequence - turn ON all the bottom switches while starting so that bootstrap capacitor gets charged.
    ->We didn't take care of your mention(the switching sequence - turn ON all the bottom switches while starting so that bootstrap capacitor gets charged.)
       We will try it!
      
    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    Guru 27525 points

    Navaneeth san

    We tried "turn ON all the bottom switches while starting so that bootstrap capacitor gets charged".
    However, in case of  VDC+ and VDC- = DC24V, we could not turn on all the bottom switches.
    According to VDC+ and VDC- = DC24V, there are 15.4 voltage between U,V, W_TOP_REF(floating ground) and VDC- without no high side turning on. 
    We assume that it causes of failure.
    So, do you have the same experience?

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Intellectual 2890 points

    Hello Matsumoto-San,

                                               Could you please share the following waveforms to analyze what is happening on your board?

    1. PWM input to the gate driver, VGE at IGBT, VCE and bootstrap capacitor voltage (referenced to output phase). All waveforms captured using 4 channel Oscilloscope.

    2. Input and output signal waveforms of U8 at start-up. U8 can disable the gate driver during fault conditions

    When none of the IGBT's are switched, the output phases will be around mid of DC voltage when referenced to DC- This is normal behavior.

    regards

    Navaneeth

  • 0 in reply to Navaneeth Narayanasamy
    Guru 27525 points

    Navaneeth san

    Thank you for your reply.

    We would like to send you detail information using private message on E2E.
    So, could you accept friends ship?

    Kind regards,

    Hirotaka Matsumoto