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relationship between two pwm signals - 1) for high side - PWMH and 2) for low side - PWML .

subrat nayak72
Expert 1285 points

Other Parts Discussed in Thread: DRV8312, INSTASPIN-BLDC, CONTROLSUITE, MOTORWARE

I haven used InstaSpin yet so I havent got a chance to look at the pwm signals coming out. For each half bridge, the TI piccolo sends out two pwm signals - 1) for high side - PWMH and 2) for low side - PWML . Is PWMH always inverted signal of PWML, (assuming zero dead time).. Also the dead time generator inside the TI piccolo, does it move both the pwm signals to create the dead time or just changes PWML ??  

I am trying to use a motor controller board that only takes three pwm inputs - one for each half bridge and has its own dead time inbuilt but the piccolo sends out 6 pwm inputs so I am bit confused. I have seen pwm signals on BLDC controller, just wondering if InstaSpin uses some steps where both the PWMH and PWML are ever low (with zero dead time) .

Any pictures/waveforms would be very very useful. thanks!

  • 0
    TI__Guru** 119680 points

    subrat nayak said:
    I am trying to use a motor controller board that only takes three pwm inputs - one for each half bridge and has its own dead time inbuilt but the piccolo sends out 6 pwm inputs so I am bit confused. I have seen pwm signals on BLDC controller, just wondering if InstaSpin uses some steps where both the PWMH and PWML are ever low (with zero dead time) .

    The DRV8312 EVM is a similar driver, you only provide high side, but you also have to pull the reset line, so you end up still using 6 signals.

    You can look at how we have done the code for this kit with InstaSPIN-BLDC

    C:\ti\controlSUITE\development_kits\DRV8312-C2-KIT_v128\Insta

    subrat nayak said:
    just wondering if InstaSpin uses some steps where both the PWMH and PWML are ever low (with zero dead time) .
    SPIN_BLDC

    or InstaSPIN-FOC

    C:\ti\motorware\motorware_1_01_00_13\sw\modules\hal\boards\drv8312kit_revD\f28x\f2806x\src

    subrat nayak said:
    just wondering if InstaSpin uses some steps where both the PWMH and PWML are ever low (with zero dead time) .

    H & L low / off occurs when the PWM driver is disabled.

    subrat nayak said:
    Also the dead time generator inside the TI piccolo, does it move both the pwm signals to create the dead time or just changes PWML ?? 

    per the TRG it can do rising and falling DB and you can decide if they are active on the high or the low

    http://www.ti.com/lit/pdf/spruh18

    most drivers you are probably looking at have the DB built-in though, so you don't even need to worry about it at the PWM.