WIND TURBINE & GENERATOR MAGNETS
wind turbine generator magnets – Wind power generation is one of the important applications of neodymium magnets. At present, the installed capacity of wind power in the world has exceeded 200 million kWh. However, due to excessive expansion and the sharp rise in rare earth raw materials and other factors, the overcapacity of wind power equipment is 260%.
Typical magnetic properties of sintered NdFeB for permanent magnet in wind turbines and generators
Neodymium permanent magnet is known as the third generation rare earth permanent magnet, which has the highest magnetic properties so far. The main phase of sintered Nd2Fe14B alloy is intermetallic compound Nd2Fe14B, and its saturated magnetic polarization (Js) is 1.6T < 1 >. Because sintered Nd2Fe14B permanent magnet alloy is composed of main phase Nd2Fe14B and grain boundary phase, and the grain orientation of Nd2Fe14B is limited by technological conditions, the maximum remanence of the magnet can reach 1.5T at present. Vacuum Schmelze GmbH produces NdFeB magnets with a maximum magnetic energy product (BH) max of 57 MGOe.
When designing permanent magnet motors, high-grade NdFeB is often chosen to obtain high air gap magnetic density. When the motor is running, neodymium magnets with high coercivity are required because of the existence of alternating demagnetizing field and the demagnetizing effect of instantaneous high current when the load suddenly changes.
Temperature stability of NdFeB permanent magnets
Wind turbines work in the wilderness, withstanding the test of heat and cold; at the same time, motor losses also lead to motor temperature rise. Sintered NdFeB magnets can work at 120 C.
The Curie temperature of NdFeB permanent magnet alloy is about 310 C. When the temperature of the magnet exceeds Curie point, it changes from ferromagnetism to paramagnetism. Under Curie temperature, the remanence of NdFeB decreases with the increase of temperature, and its remanence temperature coefficient (Br) is -0.095-0.105%/. The coercivity of Nd-Fe-B decreases with the increase of temperature, and the coercivity temperature coefficient beta (jHc) is -0.54-0.64%. If the appropriate coercivity is selected, the magnet will still have high enough coercivity at the highest operating temperature of the motor design; otherwise, loss of excitation will occur.
The consistency of magnetic properties of wind power Nd-Fe-B magnets
A large permanent magnet wind turbine usually uses thousands of neodymium magnets. Each pole of the rotor consists of many magnets. The consistency of the magnetic poles of the rotor requires the consistency of the magnets, including the consistency of size tolerance and magnetic properties. The so-called consistency of magnetic properties includes that the deviation of magnetic properties between different individuals should be small and that the magnetic properties of a single magnet should be uniform.
Corrosion Resistance of NdFeB Magnets
NdFeB alloys contain active rare earth elements, which are easy to oxidize and rust. In application, Nd-Fe-B should be treated as surface corrosion protection unless Nd-Fe-B is encapsulated and isolated from air and water. Common anticorrosive coatings are nickel plating, zinc plating, and electrophoretic epoxy resin. Surface phosphating treatment can prevent NdFeB from rusting in a relatively dry environment for a short time.
Rare earth intermetallics can react with hydrogen under certain pressure and temperature. When NdFeB absorbs hydrogen, it emits heat and breaks up. Hydrogen breakage in Nd-Fe-B production process takes advantage of this characteristic.
Reliability of Neodymium Magnetic Steel
The design life of the wind power generator is 20 years, that is to say, magnetic steel is required to be used for 20 years. Its magnetic properties are not obviously attenuated and there is no obvious corrosion of magnetic steel.
In every wind turbine and generator you will find one or more incredibly strong magnets. Simplified, the rotating shaft of a wind turbine is connected to one or more strong magnets, usually neodymium magnets, these magnets turn relative to an assembly of coiled wire, generating voltage in the coil.
Here you will find a selection of some of the strongest magnets available to buy and specially designed for use in wind turbines and generators.
Some of these super high performance magnets are trapezoid shaped so that 12 magnets will fit onto a 300mm diameter steel disc with 10mm between each on the internal diameter.