Abstract
This thesis develops a switched-reluctance generator (SRG) based DC microgrid with hybrid storage, energy harvesting and grid-connected capability. The microgrid DC bus voltage is established by the wind SRG via an interleaved boost DC/DC converter. The hybrid energy storage system consists of a SRM driven flywheel, a lead-acid battery bank and a super-capacitor. While the super-capacitor bank is directly connected across the SRG output, the battery and the flywheel are respectively interfaced to the common DC bus via its bidirectional DC/DC converter. Satisfactory energy support discharging and charging characteristics are preserved by proper controls. In addition, a chopped dump load is equipped for avoiding bus over-voltage in the occurrence of energy surplus. The isolated grid-connection of the established microgrid to utility grid is achieved by a bidirectional LLC resonant converter and a bidirectional single-phase three-wire (1P3W) inverter. The schematics and control schemes of these two power stages are all properly designed and implemented. Good inverter output waveforms are obtained via the designed proportional plus resonant control scheme. And the microgrid-to-grid (M2G) and the grid-to-microgrid (G2M) bidirectional operations can be smoothly conducted. To further enhance the power supplying quality of the established microgrid, a three-phase Vienna SMR based energy support scheme (ESS) is developed. As wind and stored energies are deficient, the possible harvested AC and DC sources can be plugged into the ESS to provide energy support for the microgrid. The control schemes of all the established power converters are realized digitally and evaluated experimentally.