Counter-rotating electric generator for wind power plants with liquid metal energy transfer

Abstract

The problem of creating effective structures that ensure mutual rotation of the rotor and stator of an electric generator. The wide practical application of counter-rotor wind-electric generators, which provide a significant increase in specific power, is hindered by the disadvantages and low reliability of existing systems for removing electric energy from the windings of a rotating counter-rotor, due to the dry friction mode. It is possible to increase the reliability of the contact removal of electrical energy from the counter rotor (rotating stator) by replacing solid brushes with liquid metal contact groups, which will lead to a certain increase in the resistivity of the contact group, compensated by the contact area of the liquid metal with the contact ring. It is most advisable to use liquid metal contact groups based on gallium, which will raise the permissible temperature limit of operation by about 2 times compared to the achieved level to 275 °C and, thereby, additionally raise the specific power of the electric generator.

An analytical formula for back EMF waveform of a counter‐rotating dual‐rotor non‐slotted axial flux permanent magnet synchronous machine

“…Since the proposed structure has two rotors, it exhibits twice the power density compared to the single-rotor structure [28,29]. In addition, the use of PM in the proposed structure leads to an increase in the reliability of counter-rotating wind turbine systems [3,31]. This structure is a good candidate to use in high-toque and low-speed applications such as gearless elevators [15].…”

Comparative analysis of torque-adding wind energy conversion systems with a counter-rotating vs. conventional electric generator

“…Regarding the electric generators for WECS, Booker et al (2010) andHabash et al (2011) proposed the use of counter-rotating electrical generators for wind turbine applications in urban areas, which have a mobile rotor (GR) and mobile stator (GS) rotating in opposite directions due to their increased energy performance compared to the conventional (with a fixed stator GS) generators. The counter-rotating generator was further investigated in terms of performance and rotor topology by Kutt et al (2020), Egorov et al (2021), andMirnikjoo et al (2021) and in terms of optimized system configuration with counter-rotating rotors (Mirnikjoo et al, 2020;Ullah et al, 2022a;Ullah et al, 2022b). Cho et al (2017) analyzedthe performance and control of a WECS with counterrotating rotors and counter-rotating generator and concluded that this configuration can lower the tip speed ratio at which the power curve attains its maximum almost by half in comparison to the single-rotor system.…”