Nonlinear Control of Electronic Capacitor for Enhanced Stability and Dynamic Response

This article focuses on improving the control structure of electronic capacitor (EC), formed by a bidirectional dc-dc converter terminated with small auxiliary capacitance. Typical application of such a system is mimicking the dynamic behavior of a bulk dc-ink capacitor while actually employing a component with much lower capacitance value. It was previously revealed that EC may be treated as output-voltage regulated wide-input-range converter feeding a bidirectional power load. Dual-loop voltage-current linear cascaded regulator, typically employed for EC terminal voltage control, imposes slow unstable mode when absorbing power from the dc-link. This article demonstrates that performing a transformation from voltage-current to power-energy domain by feedback linearization-based nonlinear control simultaneously eliminates the unstable mode and increases control bandwidth. Revealed findings are well-supported by simulations and experiments.