Optimisation of the Association of Electric Generator and Static Converter for a Medium Power Wind Turbine

Design of a Mean Power Wind Conversion Chain with a Magnetic Speed Multiplier

“…To quantify the level of performance, we will compare the combination of multiplier and high-speed generator to a direct drive, low speed generator: a Vernier configuration like that in Figure 10. A study carried out in [1,8] shows that the power density of this configuration is significantly better than that obtained using a more conventional configuration with a large number of poles.…”

“…It must be noted that Vernier-type interaction, of the magnetic teeth with small permanent magnets, can be achieved directly in an electric motor [1,8], which has the double advantage of being of a relatively simple design, with high performance at low speeds, for the given reasons (electromechanical conversion at high frequency). This shows its potential for direct drive use, without multiplier.…”

“…Despite its main problem, which is that it operates naturally with a low power factor (typically 0.4 to 0.7), this configuration lends itself admirably to wind turbine generator design because its mass power ratio is unrivalled in this kind of application [8]. The design of the magnetic speed multiplier conversion chain has the major advantage of allowing de-coupling between the electric problems (overheating, power factor …) and the problems arising from the Vernier effect in speed conversion.…”

“…The second, more recent, alternative is to link the generator directly to the turbine without a mechanical intermediary [8]. This method is known as "direct drive" and has become economically viable in recent years thanks to the progress made on permanent magnets.…”

“…The direct-drive method is attractive because it eliminates the weak element of the conversion chain: the speed multiplier gearbox. This is indeed a frequent source of failure, an additional noise source and may also require regular maintenance, resulting in high operating costs [8,9]. Finally, the multiplier can be the source of chemical pollution due to the lubricant oil.…”