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UCC27282EVM-335: UCC27282EVM-335

Premkumar T
Intellectual 445 points
Part Number: UCC27282EVM-335
Other Parts Discussed in Thread: UCC27282

Hello Team,

We are working on TI launchpad F280015x and UCC27282EVM-335 for BLDC motor application. We have below query while interfacing with TI driver board and launch pad.

Our application is BLDC motor driver, we have used F2800157 Launchpad and Universal motor code has been flashed on the board, We interfacing the motor with hall sensor feedback.

On the UCC27282EVM-335 Output pules getting as we excepted but after some time UCC27282EVM board is getting failed.

When we are checking in single board we not facing the issue. But when we are using 3 boards board is getting failed.

(Based on UCC27282EVM user manual followed the connection)

Thanks & Regards,

T.Premkumar.

  • 0
    TI__Genius 12915 points

    Hey,

    Thank you for your question regarding the UCC27282EVM-335.

    I have a few follow up questions to help me determine what is going on here.

    1. What is failing on the board? Is it the driver or another component that is failing?

    2. What are your operating conditions such as VCC, frequency, output voltage at the motor?

    3. Are you connecting the outputs of the EVM to the FETs, if so what FETs are they? Based on your block diagram, the output of the board goes to a gate driver. Could you provide me with a more detailed schematic or block diagram please?

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Intellectual 445 points

    Hello William,

    Thank you for your mail.

    1. UCC27282 drive board is failed,

    2. Driver board input : 12V, Frequency : 25Hz, Output voltage : 12V.

    3. Connected the EVM output to MOSFET H-Bridge circuit.

    Find the following connection diagram of UCC to individual MOSFET.

  • 0 in reply to Premkumar T
    TI__Genius 12915 points

    Hey,

    It appears that your setup is as expected.

    Are you able to provide waveforms such as LO, HO, and HS of when the board is working? 

    What duty cycle and dead time are you operating at as well?

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Intellectual 445 points

    Hello William,

    50% Duty cycle, 0 Dead band time.

    Find the attachment of waveform of LO and HO. HS feed back of gate driver.

    Thanks,

    T.Premkumar.

  • 0 in reply to Premkumar T
    TI__Genius 12915 points

    Hey,

    So with zero dead time, you will have what is called shoot through, where the high side and low side are on at the same time which damages the driver. This occurs because the input to output signals are not perfect and so the output waveform would have some overlap in HO and LO being on. This device (UCC27282) has interlock to prevent this but it will not operate as expected.

    So, in order to fix this, you need to implement some dead time by shortening the duty cycle of one of the signals. With the fall time (t_f) being 10ns and the rise time (t_r) being 12ns. You need at very minimum 10ns because you need to ensure that the first signal falls before the next signal rises to the high state. I would not recommend trying this at 10ns due to inconsistencies in input signals and internal delays in the driver could still cause the shoot through condition.

    Also, with such a low frequency, your bootstrap capacitor needs to be large enough to drive the high side for the duration of the high side ON state. Upon increasing this capacitance, the bypass capacitor will also need to be increase to account for biasing. This should be 10 times larger than the bootstrap capacitor.

    Let me know if this doesn't solve your problem or you have any further questions.

    Thank you,

    William Moore