Application of simple adaptive control to a DC/DC boost converter with load variation

Output voltage of a DC/DC power converter is likely to be distorted if variable loads exist in the output terminal. Unlike the buck type converter case, the regulation problem of the boost (step-up) converter is particularly difficult because the system is non-minimum phase with respect to the output voltage to be regulated. This paper presents a simple adaptive control (SAC) approach to maintain a robust performance against load variation of a boost DC/DC power converter system. In order to apply the SAC algorithm the transfer function of the controlled plant should be almost strictly positive real (ASPR). Since the converter system does not possess ASPR, a parallel feedforward compensator (PFC) is needed to implement the SAC algorithm. We first design a PI controller and make a series connection with the linearized model of the power converter at the operating point. Then a stabilizing PD controller is constructed for the connected system. Inverse of the obtained PD controller is used for the PFC that renders the parallel-connected system to be ASPR. Computer simulations show the effectiveness of the proposed control algorithm.