Combining Time and Frequency Domain Design in Current Control to Optimize Command and Disturbance Response
Christoph H. van der Broeck, Marc S. Petit, Bulent Sarlioglu, Rik W. De Doncker
This paper presents a model-based design method for current controllers of pulse-width modulated converters. It demonstrates how the command-tracking and disturbance rejection behavior of current controllers must be designed separately via appropriate state-feedback and feedforward paths, as well as feasible references to yield an optimized system behavior. The method features a state-feedback design in the frequency domain that optimizes the load and disturbance voltage response and illustrates important design limitations. The state-feedback design in the frequency domain is effectively linked to the time domain to facilitate a physically understanding of all control design decisions. For optimized, high-bandwidth command tracking, a trajectory filter generates feasible references for the state-feedback control, as well as for command-feedforward. The trajectory filter takes into account the available voltage margin and limits the di/dt of the trajectories to prevent saturation of the feedback controller and eliminate any windup issues. The proposed design method is evaluated based on experiments that validate its wide applicability.