Buck-boost converter controlled by hysteretic PWM method with input voltage feedforward

This paper proposed a new control method employing a hysteretic PWM controller with an input voltage feedforward for the boost and buck boost converters without using a current mode control. A triangular and hysteretic window voltages to generate the switching pulse signal are obtained in the comparator circuit by adding two resistors and an RC integral network. The feedforward signal from the input voltage is fed to the comparator circuit through a simple RC differentiator. As a result, the proposed control method provided excellent dynamic performances for the changes of the load current and input voltage.