• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 622 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5109B: Problem in Driving MOSFET in application of 3-Phase BLDC MOTOR Driver

Abhi Choksi
Intellectual 500 points
Part Number: LM5109B

Please go through attached schematic in which LM5109BMA/NOPB is used as gate driver for Three-Phase bridge.IRF530PBF is used as MOSFET Switch.

PCB-BLDCDRVR-1918-1B-01.pdf

Problem Definition: Supply Get Shorted while applying 6-Step PWM.

Set up information:
-> We have 10V power supply with current capability of 1Amp which is connected to the CON11
-> We have 0V-60V variable power supply with enough current capability, which is connected to the CON2 for Vcc.
-> we have MCU card which is connected to this driver board for supplying PWMs for Motor control.
-> No motor is connected for load.

Problem Steps:
Step-1:- Connected MCU card with MOTOR Driver Board.
Step-2:- Connected 10V Power supply to CON11 and set it to 10V.
Step-3:- Connected 60V Variable Power Supply to CON2 and set it to 0V.
Step-4:- Applied inputs as per the below and no supply shorting observed

MCU_A MCU_~A MCU_B MCU_~B MCU_C MCU_~C Supply Shorting
Case-1 1 1 1 1 20KHz PWM 20KHz Complementry PWM No Shorting upto Vcc=60V
Case-2 1 1 20KHz PWM 20KHz Complementry PWM 1 1 No Shorting upto Vcc=60V
Case-3 20KHz PWM 20KHz Complementry PWM 1 1 1 1 No Shorting upto Vcc=60V

Step-5:- Applied 6-Step PWM and checked for supply shorting.From Vcc=0V to 2V no shorting observed.Supply start shorting when we sweep Vcc from 2V to 3V.It also remained shorted for Vcc>3V.

I have checked for dead band and its 2us which is enough.I am sure that supply doesn't get shorted due to dead band because its enough.I have also verified 6-step PWM and its ok.So this is not an software issue.

I have also verified output of gate driver ICs and check for dead band at there also.No issue observed.There is enough dead band between HO and LO of Gate driver IC.

I need support to reach root cause of this issue.


Let me know for any required information.

  • 0
    TI__Mastermind 23155 points

    Hello Abhi,

    Thank you for the interest in the LM5109B. I am an AE with the High Power Driver group and will help to resolve your concerns.

    From the description, it seems you have confirmed the PWM outputs from the controller and the gate drive signals from the driver. With 2us dead time it is not clear why you would see a short from VCC to ground.

    Without the PWM signals applied, have you confirmed there is no issue with increasing the VCC? Maybe there is an unexpected error on the board which is causing excessive current draw from VCC.

    Assuming the board connections and components are correct, I would need to see some scope waveforms to be able to provide better advice.

    Record scope waveforms of the following:  driver LO, HO and HS to ground. Record several switching cycles, and record one cycle to confirm timing and amplitude. Record with VCC as high as reasonable. Also record driver LI, HI, LO and HO. If possible record HO-HS with a differential probe. Also record several cycles and one cycle. Confirm that all 3 phases behave the same, and the timing is as expected.

    Regards,

    Richard Herring

  • 0 in reply to Richard Herring
    TI__Genius 13445 points

    Hi Abhi, 

    We have not heard from you in a while, we must assume that you've resolved the problem and therefore mark this thread as "resolved". If so, please let us know by clicking the green button and sharing the resolution for other e2e users to learn from. 

    If however the issue is not resolved, please let us know by further posting on this thread and we will happily assist.

    Thanks.

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    Intellectual 500 points

    I am in progress to take snapshots of CRO.

    Once i get i will post here.

  • 0 in reply to Abhi Choksi
    TI__Mastermind 23155 points

    Hello Abhi,

    Whenever you have additional data and questions, post the information and we will help.

    Regards,

    Richard Herring

  • 0 in reply to Richard Herring
    TI__Mastermind 23155 points

    Hello Abhi,

    To help us better manage our communications response, It will help if we can close this thread, and when you are ready with additional information you can post back on this thread.

    Regards,

    Richard Herring