Control of Nonminimum Phase Load Current in a Boost Converter Using Output Redefinition

Control of the output current of a boost type dc-dc converter is challenging due to the nonminimum phase characteristic between the input duty cycle and output load current, and the nonlinear dynamics of the converter. This paper presents a control strategy which utilizes the method of output redefinition combined with a nonlinear control scheme to regulate the output current of the converter when operating in the continuous conduction mode. The output redefinition concept relies on defining a new output to make the system minimum phase, or marginally minimum phase, so that a robust controller can be designed. To this end, a nonlinear feedback linearization controller is proposed based on a circuit-averaged model of the converter. Furthermore, control in the discontinuous conduction mode is studied and a switching scheme is presented to regulate the output current of the converter regardless of the operation mode. The control scheme can achieve small regulation errors while providing robustness due to the minimum-phase characteristic of the new output. Numerical simulations and experimental results are presented to evaluate and verify the performance of the proposed control scheme.