In the ePWM block you need to enable the deadband. You should set the delay mode, the rising and the falling edge value according to your preferences. If you want no deadband keep the values at 0 but I would recommend using it to protect the converter. What is important is to set the polarity to "Invert Falling Edge Delay on B" and for Input Select DbA in=PWMA, DbB in=PWMA. This way you are inverting the signal of PWMB and both PWMA and PWMB share the same input which is of PWMA (this means you don't need to connect PWMB as it is being triggered by PWMA). Also make sure to set the triggers for PWMA under CMPA.