Design of Prefilter-based Current Controllers Attaining Maximum Bandwidth with Optimized Overshoot and Settling Time

Abstract

Proportional-integrative (PI) controllers are the most simple and widely-used regulators for inductor current control in power converters. Switching and sampling delays limit the controller gain attainable in practice. When this gain is maximized to optimize the disturbance rejection capabilities of the converters, corresponding tracking step response are characterized by significant overshoot and prolonged settling time. On the other hand, selecting a lower gain enables to obtain overshoot-free tracking step response with minimized settling time at the expense of worsened disturbance rejection performance. The paper proposes to prefilter the inductor current reference while maximizing the controller gain to simultaneously attain optimized disturbance rejection capability and overshoot-free tracking step response with minimized settling time. Analytical prefilter design guidelines are provided and accurately verified by simulations.