Multilevel Inverter for Wave Power Conversion

Abstract: This thesis deals with the electrical system analysis of a Wave Energy Converter (WEC) for the objective of grid connection. The Linear Permanent Magnet Generator (LPMG) is modeled and validated with experimental results. The comparison studies establish that this model is useful for the subsequent system modeling and performance analysis. To simplify the generator side control, diode bridge rectifiers are used for rectification. To reduce the size and cost of energy storage elements, DC voltage regulation is done using a DC/DC converter. Since the buoy has limited control, the electrical system needs additional design requirements. Moreover, to achieve smooth and high power, many WEC are connected to a common DC link. As a result, the inverter for the DC/AC conversion should be capable to withstand the low frequency instantaneous power peaks. Conventional multilevel inverters are considered for the initial analysis. The Neutral Point Clamped (NPC) inverter is chosen for the detailed analysis due to its advantages over other topologies. Voltage balancing technique and current control method are examined. The experimental performance of NPC converter for the WEC will be the focus in future.