Robust High-Performance Inverter Control Using Discrete Direct-Design Pole Placement

A robust high-performance discrete controller, with a simple implementation and characterizable performance that lend it to high-power industrial applications, is proposed. Discrete direct-design pole placement allows the use of common design parameters such as damping ratio and bandwidth (BW) to define the controller´s response. High performance is demonstrated with example systems achieving BWs twice as high as those of traditional cascaded current- and voltage-loop controllers. The controller is shown to be robust against component variations and many different load types, including low-impedance grid connections. Comparisons between the proposed controller and a discretized full-state-feedback continuous-time-derived controller are made and show significant improvements in both BW and stability margins. Practical tests on a parallel 2-MVA test system demonstrate a close correlation with the analysis, with an error of less than 1%.