LMG3410R070: Totem Pole converter

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Replies: 5

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Part Number: LMG3410R070

Dear Sir

I have developed a half bridge daughter card using LMG3410R070rwht GaN Device. Initially this Gan half bridge board was tested in boost converter configuration (synchronous switching). The board was loaded upto 1kW( 200V input, 400voutput, 100khz, 50% duty cycle, 5A input current) and its operation was fine. Now we are planning the same half bridge card for a 1.1kW totem pole converter. For 50Hz switching, combination of STW77N65M5 MoSFET and UCC27714D MoSFET driver is used. 

We used the same half bridge for a totem pole converter but we have seen some failures in the GaN device. We have provided constant duty (50%) with a dead time of 120ns. We are getting boost output but failure above 150V. also the shape of the output is not satisfactory. Attached the image of the output voltage(green). Kindly suggest…

5 Replies

  • Hi Akhil,

    May I know where the channel 1 and channel 2 waveforms are measured? For channel 2, it seems to be an AC voltage added on top of the DC voltage. Is that expected?

    Also could you let us know what kind of fault you are seeing? Could you capture a waveform when the fault happens (trigger at fault signal falling edge)?

    Thanks!

    Yichi Zhang

    Applications Engineer

    ti.com/GaN

  • In reply to Yichi Zhang.:

    Dea Yichi

    channel 1 - AC Line sense voltage

    channel 2- open loop output voltage of the totem pole converter when 50% duty cycle is applied. the output voltage got is not expected. this is one of the problem, output voltage got is like the sum of ac and dc voltage.

    when we reaches the 125V input, the board burnt due to heat.

    we are given switching scheme as per TI document(50% switching during positive and negative half cycle with respect to line frequency synchronization)

  • In reply to Akhil A:

    Hi Akhil,

    Could you share the schematics of the circuit? Also do you have any zoomed-in waveform at the switch node of the GaN?

    For the damage of the board, do you see physical damage on the GaN FET?

    Thanks!

    Regards,

    Yichi Zhang

    Applications Engineer

    ti.com/GaN

  • In reply to Yichi Zhang.:

    Dear Yichi

    i have attached the pwm signal for high frequency switch and low frequency mosfet. also i have attached the output voltage(yellow)d switching node voltage with respect to ground for your reference. kindly advice

  • In reply to Akhil A:

    Hi Akhil,

    As the boost converter configuration works with high voltage, we suspect the problem you are seeing related to the control of the totem pole PFC. Let me try to loop in other engineers to help. Thanks!

    Regards,

    Yichi Zhang

    Applications Engineer

    ti.com/GaN