A linear damping scheme for higher order dc-dc converters supplying constant-power loads in a dc microgrid

A linear controller is proposed for dc microgrids with SEPIC, Cuk and Zeta power electronic converters supplying constant power loads. The controller is implemented in two stages. During the first stage, also known as active damping stage, limit cycle oscillations are damped by inserting a virtual resistance in series with the input inductor of each of the converters. In the second stage, an integral controller is added to the first stage to compensate for the voltage deviations due to the virtual resistance. The second stage, also known as voltage regulation stage maintains the microgrid voltage within acceptable limits in the event of source and load variation. Linearization and small signal analysis are used to derive stability conditions for the equilibrium points. Simulation and experiments performed on a prototype microgrid are used to verify the proposed control laws.

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