Dynamics of Input-Voltage-Feedforward-Controlled Buck Converter

The use of input-voltage-feedforward (IVFF) control has become a popular method to implement a reduced-cost bus converter in the DC power systems known as intermediate bus architecture (IBA), because the IVFF control can provide adequate output voltage accuracy in respect to the variations in the input voltage even at open loop, when applied to a buck converter. The method in itself is well known from 1980´s but the dynamical features the method would provide have not been fully investigated and reported. This paper provides the theory behind the IVFF control according to which the dynamical properties of the associated converter are studied and experimentally verified. According to the investigations, the properly implemented IVFF control would provide input-to-output noise attenuation comparable to the peak-current-mode controlled converter, the voltage-loop gain largely independent of input voltage, highly reduced input-filter interactions but also increased sensitivity to negative-resistor-oscillation (NRO) phenomenon even at open loop