TMS320F28335: how to disable epwm module after a certain time in simulink

Hi, I have generated PWM signals to be used in open loop svpwm control for f28335 in the matlab/simulink environment. However, I want to stop generating these signals after a certain period of time. I have researched this in detail but couldn't find a solution in the simulink environment. The trip zone unit has been suggested to disable the epwm, but I don't know how to use it. I hope you can help. (I am not use any adc module in my system)