Abstract
A tubular permanent-magnet linear generator is suitable for direct drive wave energy conversion owing to its simple structure, easy maintenance and high efficiency. In this study, a novel Gramme winding tubular permanent-magnet linear generator (GW) is designed to increase power density. First, the structure of the Gramme winding and concentrated winding tubular permanent-magnet linear generator is introduced and the operation principle of the generator is analysed. Second, the initial parameters of GW are determined based on the similar overall dimensions to those of the concentrated winding tubular permanent-magnet linear generator. Third, the air gap flux density, external characteristics, voltage regulation, output power, and loss of the two generators are compared. Finally, the DC load capacities of the two generators are compared based on a three-phase full-control bridge rectifying circuit. The results show that the GW has a higher power density than the latter.
Highlights
A permanent-magnet linear generator adopts a permanent magnet as the excitation system, which helps eliminate the brush, slip ring, and copper loss of the excitation winding. This generator has the advantages of a simple structure, high reliability, low maintenance cost and high efficiency, making it the best choice for direct drive wave energy conversion (DD-WEC)
On the basis of traditional Gramme winding described in [16,17,18,19], this paper proposes a novel Gramme winding tubular permanent-magnet linear generator (TPMLG) (GW), which is characterized by the winding directions of all phase windings are in the same direction, and its minimum unit is 2-pole and 3-slot
The air gap flux density, external characteristics, voltage regulation, and output power generators are analysed by using finite-element method
Summary
A permanent-magnet linear generator adopts a permanent magnet as the excitation system, which helps eliminate the brush, slip ring, and copper loss of the excitation winding. The winding effectively reduces the harmonic content of the EMF and improves the power density and efficiency [9,10,11]. The harmonic content of EMF of the generator is further reduced, so the output power and power density are improved [12,13,14,15] These two types of generators use the traditional centralized fractional slot winding, the winding factor of this type of generator is relatively low, which has negative effects on the amplitude of EMF, output power and power density. The research shows that it has a high winding factor, further improves the power density of the TPMLG, and compared with the concentrated winding TPMLG (CW) proposed in the [12].
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