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The doubly salient permanent magnet generator (DSPMG) is widely known as an efficient machine for electrical production from renewable energy. In this paper, we aim to improve the output power of the DSPMG using a structural modification, which is targeted for low-speed electrical generations. Structural parameters including the stator pole depth, thickness of permanent magnet, stator pole arc, and number of winding turns were adjusted, then an optimal value of those parameters was selected based on the characteristics of the generator tested during no-load and on-load conditions. Simulations were based on the finite element method. The generator was targeted to be used for the rated power of 200 W. It was found that the optimally designed generator had a higher electromotive force of 36.1%, a lower cogging torque of 20%, and a higher output power of 12.2% than the conventional structure. The leakage flux of the proposed structure was also improved from the conventional one. Thus, the generator designed in this work could be another capable choice for electrical generation from renewable energy. The proposedly modified technique can also be adapted for output profile improvement of the doubly salient permanent magnet machines which are extensively used for renewable energy production nowadays. [ABSTRACT FROM AUTHOR]

This research project investigates the impacts of the rotor and generator sizes on rotational speed and voltage output of a direct-drive hydrokinetic turbine system. It searches for a possibility of reducing the generator size while possessing the capability to produce sufficient voltage at an ultra-low RPM. The system has a Darrieus rotor that directly drives an axial-flux permanent-magnet generator, hence the friction loss from the transmission system is eliminated. However, the direct-drive system possesses a very low rotational speed, which adversely affects the generator. In particular, the output voltage is not sufficient for regular applications or the generator diameter needs to be enlarged. Numerical models of the rotor and generator were constructed in MATLAB. The rotor and generator sizes were varied under several design conditions. The models delivered design parameters for the system and their relationships. It was found that designing the generator with 50/60 Hz electrical frequency limits the number of slot/phase and hence the maximum output voltage. The study makes a case for designing a generator with electrical frequency other than the standard frequency, where it would be novel to be able to produce a higher voltage when a location with high water velocity is available, in addition to an improved power production. It would allow the generator to produce higher voltage at a given water velocity and rotational speed or have a smaller diameter at a given output voltage. [ABSTRACT FROM AUTHOR]