Control of a two-port supercapacitor converter based on differential flatness principle for transportation applications

This paper presents a new control strategy for dc-link stabilization in weak transportation networks that use supercapacitors as the energy storage unit. A two-port isolated converter based on a dual active bridge topology is presented, and a reduced-order mathematical model of the system is described for power plant control. Using a nonlinear control approach based on the flatness property, we propose a simple solution to dynamic and stabilization problems in the power electronics systems of transportation networks. The controller design parameters are independent of the operating point at which interactions between the dc main substation, loads and energy storage unit are taken into account by the controller. To validate the proposed method, a hardware system is modeled using digital estimation with a DS1103 dSPACE controller platform. We analyze a prototype small-scale network that uses a 1 kW six-pulse rectifier as a dc substation and a 250 F, 32 V supercapacitor bank as an energy storage substation. Finally, the utility of the control algorithm is validated using experimental results measured during motoring mode, ride-though, and braking mode drive cycles.