Intrinsically stable realization of a resonant current regulator for a single phase inverter

Abstract

AC current regulation in a single phase inverter is predicated on the ability of a resonant controller to effectively track a sinusoidal reference signal with a nominal frequency dependent on the application. Due to the presence of poles residing in a marginally stable location of the complex plane, the explicit implementation of resonant regulators is subject to unbounded dynamic excitation in the event of the control signal entering the non-linear saturation region. Addressing this issue, it is proposed within this paper that an amalgamated approach is taken to the design and implementation of a resonant controller for a single phase current regulator with an intrinsic stable implementation form that naturally avoids the use of marginally stable dynamic states. Using a disturbance observer, the presented method embeds a pair of marginally stable poles in the closed form of the controller, constituting the resonant action. As a consequence, this allows accurate tracking of a sinusoidal reference signal whilst retaining a stable realization of the implementation form. Simulation results are presented to demonstrate the efficacy of the proposed approach. Experimental results are currently being investigated.