Permanent magnet DC motors can be classified into brushless permanent magnet DC motors and brushed permanent magnet DC motors based on the presence of brushes. These motors utilize a permanent magnet to establish a magnetic field and find wide applications in various portable electronic devices and appliances, such as recorders, VCD players, turntables, electric massagers, toys, as well as in automotive, motorcycle, hand dryers, electric bicycles, batteries, cars, ships, aviation, machinery, and other industries. They are also extensively used in high-precision products like video recorders, photocopiers, cameras, mobile phones, precision machine tools, banknote counting machines, and currency counters.
Permanent magnet DC motors function by utilizing one or more permanent magnets to establish a magnetic field. Similar to separately excited DC motors with a stable excitation current, these motors can easily adjust their armature voltage and offer advantages such as small size, high efficiency, simple structure, and low copper loss compared to separately excited DC motors. They are the primary type of low-power DC motors.
Considerations for the application of permanent magnet DC motors include:
Reverse Braking Operation: Unless explicitly stated otherwise, permanent magnet DC motors generally should not operate under reverse braking at rated voltage to prevent demagnetization of the permanent magnet. If reverse braking is necessary, a current-limiting resistor should be added to restrict excessive current.
Quality Inspection:
Examine the external appearance of the motor for scratches, dents, or coating peeling.
Check the rolling shaft for smooth and flexible rotation without apparent sticking.
Ensure secure motor connections and check for any live operation.
Verify that the motor exhibits no conflicts during rolling, with particular attention to bearing conflicts. Bearing wear may result in abnormal noise, localized overheating, and temperature rise.
Disassembly Precautions:
Pay attention to excessive current, temperature changes, and demagnetization caused by opening the magnetic circuit, especially when disassembling. It is necessary to perform magnetic short-circuit maintenance on the permanent magnet magnetic circuit during disassembly to prevent self-magnetization after demagnetization.