permanent magnet

Correct selection of permanent magnet motor power   Demagnetization is related to the power selection of the permanent magnet motor. Correctly selecting the power of the permanent magnet motor can prevent or delay demagnetization. The main reason for the demagnetization of the permanent magnet synchronous motor is excessive temperature, and overload is the main reason for excessive temperature.   Therefore, when selecting the power of the permanent magnet motor, a certain margin should be left. According to the actual load situation, about 20% is generally more appropriate.     Avoid heavy load starting and frequent starting   Cage-type asynchronous starting synchronous permanent magnet motors should avoid heavy-load direct starting or frequent starting.   During the asynchronous starting process, the starting torque is oscillating. In the starting torque trough section, the stator magnetic field has a demagnetizing effect on the rotor poles. Therefore, try to avoid heavy-load and frequent starting of asynchronous permanent magnet synchronous motors.   Improved design   1. Properly increase the thickness of the permanent magnet   From the perspective of permanent magnet synchronous motor design and manufacturing, the relationship between armature reaction, electromagnetic torque and permanent magnet demagnetization should be considered.   Under the combined effect of the magnetic flux generated by the torque winding current and the magnetic flux generated by the radial force winding, the permanent magnet on the rotor surface is prone to demagnetization.   In the case of the motor air gap remaining unchanged, the most effective way to ensure that the permanent magnet does not demagnetize is to appropriately increase the thickness of the permanent magnet.   2. There is a ventilation slot circuit inside the rotor to reduce the rotor temperature rise   If the rotor temperature rises too high, the permanent magnet will lose its magnetism irreversibly. When designing the structure, a ventilation circuit can be designed inside the rotor to directly cool the magnetic steel. This not only reduces the magnetic steel temperature, but also improves efficiency.

The biggest risk in the use of permanent magnet motors is demagnetization caused by high temperature. As we all know, the key component of permanent magnet motors is neodymium magnet, and neodymium magnet is most afraid of high temperature. It will gradually demagnetize under high temperature for a long time. The higher the temperature, the greater the risk of demagnetization.   Once a permanent magnet motor loses its magnetism, you basically have no choice but to replace the motor, and the cost of repair is huge. How do you determine whether a permanent magnet motor has lost its magnetism?   1. When the machine starts running, the current is normal. After a period of time, the current becomes larger. After a long time, the inverter will be reported to be overloaded.   First, you need to make sure that the inverter selected by the air compressor manufacturer is correct, and then confirm whether the parameters in the inverter have been changed. If there are no problems with both, you need to judge by back electromotive force, disconnect the head from the motor, perform no-load identification, and run no-load to the rated frequency. At this time, the output voltage is the back electromotive force. If it is lower than the back electromotive force on the motor nameplate by more than 50V, it can be determined that the motor is demagnetized.     2. After demagnetization, the running current of permanent magnet motor will generally exceed the rated value.   Those situations where overload is reported only at low or high speed or occasionally reported, are generally not caused by demagnetization.   3. It takes a certain amount of time for a permanent magnet motor to demagnetize, sometimes several months or even one or two years.   If the manufacturer selects the wrong model and causes current overload, it does not belong to motor demagnetization.   An important indicator of permanent magnet motor performance is the high temperature resistance level. If the temperature resistance level is exceeded, the magnetic flux density will drop sharply. The high temperature resistance level can be divided into: N series, resistant to more than 80℃; H series, resistant to 120℃; SH series, resistant to more than 150℃. The motor's cooling fan is abnormal, causing the motor to overheat. The motor is not equipped with a temperature protection device. Ambient temperature is too high. Improper motor design.

Demagnetization may be caused by a variety of factors, including: high temperature, physical shock or long-term time-induced natural decline in magnetism.   Specifically, when a permanent magnet is subjected to high temperatures, the magnetic dipoles inside it lose their ordered arrangement, causing the magnetism to weaken or disappear.   For example, the Curie temperature of permanent magnets is relatively low, and once their maximum operating temperature is exceeded, the magnets will gradually demagnetize.     In addition, physical shock may also cause demagnetization of permanent magnets because the shock may change the arrangement of magnetic dipoles, destroying the magnetic domain structure and thus affecting the magnetic properties.   Over time, even if a permanent magnet is not subjected to significant physical shock or high temperatures, its magnetism may naturally decay, because the arrangement of the magnetic dipoles may gradually become disordered, resulting in a weakening of the magnetism.   This depends on the external conditions the magnet encounters and the properties of the permanent magnet itself.  

The magnetic arc industry is set to thrive in the coming years, driven by advances in the design of permanent magnet motors and the growing demand for neodymium magnets from a wide range of industries.    Magnet Arcs in Motor Design   Permanent magnet motors rely on arc magnets to create consistent magnetic fields in rotors, enabling smoother and more efficient operation. With the increasing adoption of electric vehicles and industrial automation, the demand for high-quality arc magnets is growing. The shift toward renewable energy systems, including wind turbines, is also increasing this demand.   Wholesale Supply and Customization   Wholesale markets for neodymium magnets, including neodymium arc, are expanding rapidly. All manufacturers require magnets that meet high quality and dimensional standards for different uses. Companies like Huajin are equipped to provide customized solutions, addressing specific needs in motor production, medical equipment, and consumer electronics.     Key Applications Driving Growth   Electric Vehicles: Arc magnets are integral to the lightweight, high-performance motors that power modern EVs. Renewable Energy: Permanent magnet generators in wind turbines utilize arc magnets for consistent energy conversion. Industrial Tools: Precision tools and machinery benefit from the reliable strength of neodymium arc magnets.   For businesses seeking dependable supply and innovation, Nanjing Huajin Magnet Co., Ltd. offers unmatched expertise in the production of high-performance neodymium magnets. With a focus on customization, quality, and scalability, Huajin is poised to support the evolving demands of this dynamic industry.     For more details about our products and solutions, explore our offerings on neodymium magnets and their applications. Let's shape the future of magnetic technology together!          

As a high-performance magnetic material in modern industry, NdFeB permanent magnets promote the progress of contemporary technology and society and are widely used in various fields. How to judge the advantages of permanent magnet products: 1. Magnetic properties; 2. The size of the magnet; 3. Surface coating.   1. Magnetic properties：First, the key to the decision is to control the magnetic properties of the raw materials during the production process.   Raw material manufacturers can choose mid-range or low-grade sintered NdFeB according to business needs. In accordance with the national standards for purchasing raw materials, our company only sells high-grade NdFeB.   The quality of the production process also determines the performance of the magnet.   Quality control during production is important.     2. Magnet shape, size and tolerance: Utilize various shapes of NdFeB magnets, such as round, special-shaped, square, arc-shaped, trapezoidal. Different sizes of materials are processed by different machine tools to cut rough materials, the technology and machine operator determine the accuracy of the product.   3. Surface coating treatment: The coating quality of the surface coating, zinc, nickel, nickel-copper-nickel electroplating copper and gold and other electroplating processes. The product can be electroplated according to customer requirements.   The quality of NdFeB products can be summarized as a good grasp of performance, dimensional tolerance control, and appearance inspection and evaluation of the coating. Tests such as the Gaussian surface of the magnetic flux of the magnet; dimensional tolerance, which can be measured with a vernier caliper; coating, coating color and brightness and coating bonding strength, and the appearance of the magnet surface can be observed to be smooth, with or without spots, and with or without edges and corners, to evaluate the quality of the product.  

1. What is a motor? A motor is a component that converts battery energy into mechanical energy to drive the wheels of an electric vehicle. 2. What is winding? The armature winding is the core part of the DC motor. It is a coil wound with copper enameled wire. When the armature winding rotates in the magnetic field of the motor, it will generate electromotive force. 3. What is a magnetic field? It refers to the force field generated around a permanent magnet or electric current and the space or range of magnetic force that can be reached. 4. What is magnetic field strength? The magnetic field strength of an infinitely long wire carrying a current of 1 ampere at a distance of 1/2 meter from the wire is 1A/m (ampere/meter, SI); in the CGS unit system (centimeter-gram-second), in order to commemorate Oersted's contribution to electromagnetism, the magnetic field strength of an infinitely long wire carrying a current of 1 ampere at a distance of 0.2 cm from the wire is defined as 10e (Oersted), 10e=1/4.103/m, and the magnetic field strength is usually represented by H. 5. What is Ampere's law? Hold the wire with your right hand, with your extended thumb pointing in the same direction as the current. Then the direction pointed by your bent four fingers is the direction of the magnetic flux lines. 6. What is magnetic flux? Magnetic flux is also called magnetic flux: suppose there is a plane perpendicular to the direction of the magnetic field in a uniform magnetic field, the magnetic induction intensity of the magnetic field is B, and the area of ​​the plane is S. We define the product of the magnetic induction intensity B and the area S as the magnetic flux passing through this surface. 7. What is a stator? The part of a brushless or brushless motor that does not rotate when it is working. The motor shaft of a hub-type brushless or brushless gearless motor is called a stator. This type of motor can be called an internal stator motor. 8. What is a rotor? The part that rotates when a brushed or brushless motor is working. The outer shell of a hub-type brushed or brushless gearless motor is called a rotor, and this type of motor can be called an external rotor motor. 9. What is a carbon brush? A brush is placed on the surface of the commutator in a motor. When the motor rotates, it transmits electrical energy to the coil through the commutator. Since its main component is carbon, it is called a carbon brush and is easy to wear. It should be regularly maintained and replaced, and carbon deposits should be cleaned. 10. What is a brush holder? A mechanical guide that holds and holds the carbon brushes in place in a brushless motor. 11. What is a commutator? Inside a brushed motor, there are mutually insulated strip metal surfaces. As the motor rotor rotates, the strip metal alternately contacts the positive and negative poles of the brushes, achieving alternating positive and negative changes in the direction of the motor coil current, completing the commutation of the brushed motor coil. 12. What is phase sequence? The order in which the brushless motor coils are arranged. 13. What is magnet? It is generally used to refer to magnetic materials with high magnetic field strength. Electric vehicle motors all use neodymium permanent magnets. 14. What is electromotive force? It is generated by the rotor of the motor cutting the magnetic lines of force. Its direction is opposite to that of the external power supply, so it is called back electromotive force.