Dynamic performance of PWM DC-DC boost converter with input voltage feedforward control

Small-signal characteristics are studied for a pulse-width modulated (PWM) boost converter with input voltage feedforward control. The characteristics are valid for the continuous conduction mode (CCM). A small-signal circuit model is used to derive the input-to-output voltage transfer function (audio-susceptibility), the input impedance, and the output impedance. A response of the output voltage to a step change in the input voltage is also computed. The measured Bode plots of the input-to-output voltage transfer function agreed with that predicted theoretically. It is shown that the feedforward control may reduce the magnitude of the input-to-output voltage transfer function by 40 dB. The input resistance of the converter with feedforward control is negative at low frequencies. The output impedance is not affected by feedforward control.