The control circuit of the voltage mode control Buck converter adopts a PWM control mode, and the output voltage and the reference voltage Vref generate a control signal vcon via an error amplifier. Since the horizontal width and height of any point on the sawtooth wave are linear, when compared with the control voltage vcon, a pulse u having a width proportional to the amplitude of the control voltage can be obtained. When the input voltage fluctuates or the load changes, the closed-loop negative feedback maintains the stability of the output voltage by changing the duty ratio of the control signal u.
Like the sawtooth wave, the isosceles triangle wave can also be used as the PWM control drive signal. Through simulation and experiment, I found that the converter system is more stable when the isosceles triangle wave is used for PWM control than the sawtooth signal.
What is the reason for this?