Why are wind turbines more popular?

People generally accept wind turbines as the main source of power only because they are a clean energy source, and environmental sustainability has been a hot topic for some time. The fact that wind turbines only produce clean energy (do not emit any toxic substances to the environment) makes them the main products of the power industry, and they will stay-and the core of this purpose is the existence of permanent magnets (such as neodymium magnets). Neodymium magnets are a type of rare earth magnet. Another example is the neodymium-iron-boron combination. These turbines are used in wind turbine design to reduce costs, increase reliability, and greatly reduce the need for continuous and expensive maintenance.

How do permanent magnets work in wind turbines?

The operation of wind turbine generators is based on electromagnetic principles, usually following the first electromagnetic principle designed by Michael Faraday in 1831. When an electrical conductor rotates in a magnetic field, it generates electricity. When the blades of the turbine rotate in the wind direction, electromagnetic induction occurs in the magnetic field of the permanent magnets in the turbine to generate electricity. A generator connected to the shaft of the wind turbine will move the blades. Converted to electrical energy. However, the permanent magnet in the wind turbine does not use the slip ring used in the electromagnet, but uses the magnetic field of a strong rare-earth magnet.

What is difference between electromagnet and permanent magnet?

Unlike electromagnets, permanent magnets do not require any external power source. The main difference between using electromagnets and permanent magnets in wind turbines is that electromagnets require slip rings to power the electromagnets, while permanent magnets do not. Likewise, gearboxes require continuous maintenance, which can significantly increase costs.

The function of the gearbox is to convert the low speed of the turbine shaft into the higher speed required by the induction generator to generate electricity, but the gearbox will cause friction and reduce performance. For example, by using neodymium magnets instead of electromagnets, we can increase the efficiency of turbines, reduce efficiency and reduce maintenance costs.

Large-size sintered NdFeB magnets are mainly used to manufacture permanent magnet direct-drive or semi-direct-drive wind turbines. The use of high-performance neodymium iron boron reduces the weight of the wind turbine, making maintenance easier and more efficient. Therefore, permanent magnet direct drive wind turbines are the development trend of wind turbines in the future.

Due to the poor working conditions of the wind turbine generator in the open air, such as the seaside, the tuyere, etc., there are many requirements for the magnet.

①High remanence: The principle of wind turbine power generation is to use wind-driven blades to drive the rotor containing the permanent magnet array to generate electricity through the electromagnetic induction effect in the stator winding (conductor). The magnitude of the induced electromotive force generated at both ends of the winding is proportional to the magnetic flux density (magnetic induction) Bg generated by the large-size sintered NdFeB magnet array in the air gap, and this Bg is proportional to the square root of the maximum magnetic energy product of the permanent magnet. Therefore, the high magnetic energy product of the material is one of the parameters pursued by the generator.

②High coercivity: When the wind generator is running, the permanent magnet will be demagnetized by the alternating reverse magnetic field generated by the winding. Therefore, the wind generator requires the permanent magnet to have sufficient coercivity to resist strong reverse demagnetization.

③High working temperature: The wind turbine should work in the range of 120-40-40, and the magnet is required to have low irreversible loss within this working temperature range to ensure the normal operation of the wind turbine.

④Other physical properties:

Corrosion resistance: The atmospheric environment of wind turbines has also changed greatly. Some places are wet; the sea is not only wet, but also salty; sometimes the atmosphere may contain some alkali or acid. All of the above will have a certain corrosive effect on the large-size sintered NdFeB magnet, thereby reducing the magnetism, and even completely destroying the magnet in severe cases. In order to ensure the normal operation of the wind turbine within 20 years, it is required that the magnet does not produce significant demagnetization within 20 years. One of the factors of demagnetization is that the magnet may undergo various corrosion. Therefore, the magnet requires high corrosion resistance and proper surface treatment for corrosion protection. 

Impact resistance: The wind turbine will inevitably vibrate during operation, especially under strong wind, the motor itself will produce strong vibration, which requires the magnet to maintain its integrity and stable magnetic performance under long-term vibration.

Thermal conductivity: During the operation of the wind turbine, the magnet will generate heat due to the eddy current in the metal magnet material. In order to reduce the temperature of the magnet, the thermal conductivity of the magnet material should be as high as possible. The reduction of eddy current mainly depends on reducing the surface resistance.

Thank you for reading our article and we hope it can help you to have a better understanding of the most commonly used rare earth neodymium magnets. If you want to learn more about permanent magnets, we would like to advise you to visit BEARHEART Magnets for more information. 

We can provide high-quality permanent magnets like neodymium magnets, ferrite magnets and magnetic assembly at a very competitive price. Any inquiries and orders are welcomed.