Application of magnet in motor

Application of magnet in motor

When selecting appropriate magnet materials and motor types, various factors of the specific application scenarios need to be comprehensively considered.

For magnet materials, working temperature is crucial. In high-temperature environments like industrial furnaces and automotive engine compartments (where the temperature often exceeds 100°C), samarium-cobalt magnets with high Curie temperature, good temperature stability, and less affected remanence and coercivity are suitable. In normal-temperature environments (such as 20°C - 50°C where most daily appliances operate), neodymium-iron-boron magnets with high remanence, high coercivity, and high magnetic energy product are ideal. In extremely low-temperature environments (such as around -200°C in low-temperature physics experiments and liquid helium cooling equipment), aluminum-nickel-cobalt magnets with stable performance and resistance to irreversible demagnetization are more applicable. The requirement for magnetic field strength also cannot be ignored.

For scenarios with extremely high magnetic field requirements like MRI devices and particle accelerators, neodymium-iron-boron magnets can meet the needs. For medium magnetic field requirements in general industrial motors and speakers, cost-effective ferrite magnets are sufficient. For weak magnetic field requirements in magnetic sensors and small instruments, the weak and stable magnetic field of aluminum-nickel-cobalt magnets is easy to control. Additionally, corrosion resistance should be considered. In wet or corrosive environments such as marine engineering and chemical equipment, samarium-cobalt magnets and neodymium-iron-boron magnets with special surface treatments (such as nickel plating or zinc plating) are suitable. In dry and clean environments like the interiors of electronic devices and laboratory instruments, where the requirement for corrosion resistance of magnets is low, the choice can be made according to other performance needs.

When it comes to choosing motor types, load characteristics are important. For constant-torque loads like conveyors and cranes, DC motors or the constant-torque speed regulation mode of AC asynchronous motors can be selected. For constant-power loads such as machine tool spindles and fans, the constant-power speed regulation mode of AC asynchronous motors or permanent magnet synchronous motors is more appropriate. For impact loads like forging machinery and crushers, DC series-excited motors or wound-rotor asynchronous motors with good overload capacity and mechanical characteristic stiffness can meet the requirements. Speed regulation requirements also need to be considered. For scenarios with high-precision speed regulation requirements like CNC machine tools and robots, servo motors that often cooperate with encoders, have fast response speed and high positioning accuracy are the first choice.

For wide-range speed regulation requirements in elevators and textile machinery, AC asynchronous motors or permanent magnet synchronous motors with variable frequency speed regulation can achieve smooth wide-range speed regulation. For small devices with low requirements for speed regulation accuracy, such as household fans and small mixers, single-phase asynchronous motors with capacitor speed regulation or tap speed regulation are sufficient. Moreover, the operating environment also affects the selection of motors. In flammable and explosive environments such as the petroleum and chemical industries, explosion-proof motors such as flameproof and increased-safety types are required. In dusty environments like mines and cement plants, enclosed motors such as totally enclosed fan-cooled types can prevent dust from entering. In wet environments such as underground parking lots and sewage treatment plants, moisture-proof motors using moisture-proof insulating materials and sealed structures can avoid a decrease in insulation performance and component rusting.