PSpice PWM duty clycle generation from PID controller
It is possible to make a PWm signal using a pulse source but it is cumbersome.

The "classical" way to make a nice PWM signal is to make a sawtooth or triangle wave of the preferred frequency. You can make this wave in the simulator using a pulse source, note that you will need relatively long rise and fall times.

Then compare that wave to a DC level using a comparator or opamp.
Note that in the simualtor you will need an opamp with a selectable maximum and minimum output voltage.

Varying the DC level sets the PWM duty cycle. The output of the opamp or comparator is the PWM signal.