Direct liquid cooling for an outer‐rotor direct‐drive permanent‐magnet synchronous generator for wind farm applications

Abstract

Offshore applications, which call for the largest and most powerful wind turbines, demand a higher standard of reliability and maintainability. Direct-drive permanent-magnet synchronous generators (DD-PMSGs) are increasingly being specified for these applications. The major shortcoming to traditional high-powered direct-drive generators is extraordinary size and mass leading to extraordinary cost. To generate higher powers at low rotational speeds, directdrive generators must either develop greater tangential stresses or be larger in diameter. For traditional air-cooled generators, higher power generally means a much larger diameter. Dramatic cost savings can be realised with the development of a more effective stator windings cooling system that puts further the limit on current density enabling the development of high-power direct-drive generators of substantially smaller diameters. This study presents a direct liquid cooling system design for an 8 MW outer-rotor DD-PMSG. The approach is new for wind turbine generators, so its impact on the thermal behaviour and reliability for the total electrical machine has been evaluated and reported here. Testing of a stator coil prototype (1/72nd of the complete stator) with internal cooling liquid flow is also reported to demonstrate the workability of the designed cooling solution.

Modeling of Airgap Fluxes and Performance Analysis of Five Phase Permanent Magnet Synchronous Generator for Wind Power Application

“…It is directly connected to the turbine without any requirement of an additional gearbox [7], [8] and has several advantages like higher efficiency [9], [10], lighter rotor weight and no external excitation [11], [12]. Being a direct drive, it generates a voltage at variable wind speed and thereby, maintaining a high power factor [13]. However, it requires a full-scale converter to control the generator output voltage [14].…”

An innovative natural air-cooling system technique for temperature-rise suppression on the permanent magnet synchronous machines

“…Polikarpova, et al [4] presented a direct liquid cooling system design for an 8 (MW) outer-rotor direct-drive permanent magnet synchronous motor (PMSG). The approach was novel for wind turbine generators, so its impact on the thermal behavior and reliability for the total electrical machine has been evaluated and reported.…”

Dynamics of the fractional‐order chaotic PMSG, its stabilisation using predictive control and circuit validation

“…[13], it is a popular generator used by the wind turbine to generate electrical energy. Two cases where the compactness and efficiency of performance of PMSG are significantly required are electric vehicle drives [14], where very high torque densities are required; and wind turbine generators or PMSG [15]. The authors of this work explore the fractional dynamics of PMSG and investigate the minimum effective dimension for which chaos exists in the FOPMSG.…”