Abstract
This thesis focuses on selection and analysis of the peripheral components of a 100 kW multi-function converter. They include power switch, current sensor, inductor, magnetic connector, dc-bus capacitor and filter capacitor. Besides, this work presents selection of fan for ventilation and determination of heat sink for a burn-in test. Operational modes of the converter include grid-connection mode, rectification mode, dc-bus voltage regulation mode and uninterruptible power supply (UPS) mode. In grid-connection mode, power is transferred from dc to ac grid. In rectification mode, power is transferred from ac to dc for balancing dc bus voltage and supplying dc load. In dc-bus voltage regulation mode, according to the demand of load, the inverter changes the power flow between dc bus and ac grid to balance the energy at dc bus. If the power demand from dc bus is less than the supply from renewable energy, it will inject power to the grid. On the contrary, the power flow is changed from ac grid to dc bus. When the grid is abnormal, the converter can operate in UPS mode for keeping voltage stable and waiting for the grid back to normal. In the thesis, operational principle is described first and then the control laws based on the D- digital control are derived. Next, design and selection of components include power switch, inductor, fan, heat sink, current sensor, dc-bus capacitor, output filter capacitor and magnetic connector are presented. Since it is difficult to find a dc power supply with high power level, two converters are adopted to circulate power and their configuration is also presented. Finally, description of hardware implementation is focused on problems and solutions during burn-in test. The major contributions of this research can be summarized as follows: (1) the designed converter can achieve multi-functions which can not only reduce production cost and volume, but can execute different operation modes according to load demands, and (2) the hardware can pass burn-in test under full load of 100 kW, verifying its feasibility.