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The tethered-undersea-kite (TUSK) represents a new electric power generation concept for harvesting energy from tidal currents, with higher power density compared to traditional static tidal turbines. However, the power and rotating speed of the turbine fluctuate periodically depending on the kite's motion in the sea creating an additional challenge for the speed control of the generator. The mathematical model of the system's power generation is developed. Two alternative maximum-power-point-tracking (MPPT) algorithms suitable for this application are designed. The electrical torque of the generator is controlled directly or a more accurate closed-loop speed controller is used. The turbine inertia creates an error between the optimal-reference power and the actual generated power. This error is evaluated experimentally for both MPPT-algorithms when fluctuating mechanical torque typical for the TUSK-system is applied on the generator. Experimental results on a 35-kVA laboratory emulator are presented, where an accurate representation of the system dynamics and inertia are implemented. [ABSTRACT FROM AUTHOR]

A variable-frequency drive (VFD) having a 440-V front-end current source rectifier (CSR) interface to a voltage source inverter (VSI) feeding a Permanent-Magnet Axial-flux Air Core motor combination is a solution for low-horsepower pump and fan control that is both power dense and compatible with a shipboard environment. This paper describes the control and power platforms for the CSR/VSI and provides experimental results for a 250-V 3.3-kW system. Power density and efficiency comparisons are made between equivalent CSR/VSI- and voltage-source-conversion-based VFDs to demonstrate that the CSR/VSI-based VFD is more power dense. [ABSTRACT FROM AUTHOR]

Many forms of renewable energy exist in the world's oceans, with ocean wave energy showing great potential. However, the ocean environment presents many challenges for cost-effective renewable energy conversion, including optimal control of a wave energy converter (WEC). This paper presents a maximum power point tracking (MPPT) algorithm for control of a point absorber WEC. The algorithm and testing hardware are presented in detail, as well as simulated and laboratory test results. The results show that MPPT applied to ocean wave energy is an effective and promising control strategy. [ABSTRACT FROM PUBLISHER]

This paper presents a novel permanent-magnet tubular linear generator (PMTLG) buoy system designed to convert the linear motion of ocean waves into electrical energy. The design incorporates no working seals and a saltwater air-gap bearing surface integration between the PMTLG buoy components. The internal generator design will be discussed, in addition to the system integration with the buoy structure. The simulation and hardware results of the generator are presented. [ABSTRACT FROM PUBLISHER]