I'm currently learning about negative feedback and voltage mode control for various DC-DC converters. I'm very confused about how the control voltage changes the pwm signal, along with how the reference voltage and sensor gain are chosen. The pwm generator works by comparing the input control voltage to a ramp voltage. If the control voltage is greater than the ramp voltage the output is high and if it is lower than the ramp voltage the output is low. This results in a series of square pulses as shown below:
Why is a 5V reference voltage selected? Can it be anything? The sensor gain for this problem is selected to be 1/3. Is it 1/3 because we want the nominal output voltage to be equal to the reference voltage? I am quite lost from the part after the error comparator. Let's say that the voltage being fed-back is exactly 5V so Ve = 5-5 = 0V. If Ve is 0, how is the pwm generator able to generate any pulse signal to drive the transistor since the control voltage will be 0 coming out of the compensator?
Also, how is the ramp voltage value chosen? I would imagine that it would depend on the gain of the compensator since if the gain is too large, then the control voltage would always be higher than the ramp voltage.