Laminated Magnets achieve performance optimization, cost control, and application expansion through structural innovations, making them an important development direction in the field of magnetic materials.
Concept of Laminated Magnets
Laminated magnets are components made up of multiple layers of thin magnetic materials stacked together, isolated by insulating layers or coatings to form magnetic circuits. The primary objective of laminated magnets is to minimize eddy current loss, particularly in alternating current (AC) or high-frequency applications, thereby preventing heating and efficiency degradation caused by alternating magnetic fields.
Advantages of Laminated Magnets
| Reduction of Magnetic Domain Wall Movement Resistance: The layered structure can limit the movement range of magnetic domain walls by introducing insulating layers or low-permeability materials between the layers, thereby reducing energy loss during domain wall movement. For instance, in laminated silicon steel sheets, the insulating coatings between layers can decrease eddy current loss while also moderating the excessive movement of magnetic domain walls, indirectly affecting hysteresis loss.
| Optimization of Magnetic Circuit Distribution: The layered structure allows for a more uniform distribution of the magnetic field within the material, reducing local magnetic field concentration that can lead to excessive flipping of domains and energy losses. For example, in some high-performance magnetic devices, specific layered structures can be designed to apply a more uniform magnetic field to the magnetic material, thereby lowering hysteresis losses.
| Matching Material Properties: Different magnetic materials can be chosen for each layer based on their varying hysteresis characteristics. By combining them appropriately, the overall area of the hysteresis loop can be minimized, thus reducing hysteresis loss. For example, layering materials with high permeability but high hysteresis loss with those that have low hysteresis loss can optimize hysteresis loss while maintaining magnetic performance.
Challenges of Laminated Magnets
| Complexity of Processing: High-precision equipment is required for punching precision, laminations alignment, and insulation treatments.
| Cost: The processing cost for laminations is higher than that of solid cores, necessitating a balance between performance and budget.
Which Magnets Can Be Made Into Laminated Magnets?
| Neodymium Iron Boron Magnets: Neodymium iron boron magnets are currently one of the strongest permanent magnetic materials. Their performance can be optimized through laminated technology. For example, in new energy motors, laminated neodymium iron boron magnets are often used by dividing the magnetic steel radially into several segments and bonding them with insulation adhesive to reduce iron losses and improve motor efficiency. Additionally, the laminated design allows for balancing performance and cost by adjusting the coercivity of different layers.
| Samarium Cobalt Magnets: Samarium cobalt magnets have high magnetic energy product and good temperature stability, making them suitable for high-temperature environments. Laminated samarium cobalt magnets can be created by combining samarium cobalt materials with different properties to meet the specific needs of particular application scenarios.
Thickness of Laminated Magnets
| Electrical Motors: In high-speed rotating devices such as electric vehicle motors, the thickness of a single layer of layered neodymium-iron-boron magnets typically ranges from 0.5 mm to 2 mm.
| Magnetic Separators: In magnetic separators or filters, the thickness of layered neodymium-iron-boron magnets may range from 1 mm to 5 mm. Depending on the separation task requirements, the thickness and number of layers of the magnets can be adjusted to optimize magnetic field distribution for effectively adsorbing or separating ferromagnetic impurities.
Applications of Laminated Magnets
Laminated magnets, by reducing eddy current losses, have wide applications.
| Motors: Electric Vehicle Drive Motors: Laminated magnets minimize eddy current losses during high-frequency operation, improving motor efficiency and extending driving range. They also help minimize motor temperature rise, thereby enhancing reliability and durability, which meets the requirements of electric vehicles for high power density and long lifespan.
| Wind Turbines: Laminated magnets reduce eddy current losses in generators during variable-frequency operation, improving power generation efficiency. This is especially effective in capturing energy at low wind speeds, improving the overall performance of wind power generation.
Magnets Manufacturer
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