Shanghai Royal Machinery Co.,Ltd

Permanent magnet vsd screw air compressor PMAC motor vsd screw compressor

General introduction of permanent magnet motor:

• Permanent magnets are materials where the magnetic field is generated by the internal structure of the material itself. Inside atoms and crystals you have both electrons and the nucleus of the atom. Both the nucleus and the electrons themselves act like little magnets, like little spinning chunks of electric charge, and they have magnetic fields inherent in the particles themselves. There's also a magnetic field that's generated by the orbits of the electrons as they move about the nucleus. So the magnetic fields of permanent magnets are the sums of the nuclear spins, the electron spins and the orbits of the electrons themselves. In many materials, the magnetic fields are pointing in all sorts of random directions and cancel each other out and there's no permanent magnetism. But in certain materials, called ferromagnets, all the spins and the orbits of the electrons will line up, causing the materials to become magnetic. This would be your normal iron, cobalt, nickel. Permanent magnets are limited by the structure of the material. And the strongest magnetic field of a permanent magnet is about 8,000 gauss. The strongest magnets here at the Magnet Lab are 450,000 gauss, which would be almost 50 times stronger than that.

The difference between Permanent Magnet AC (PMAC) motors differ from AC Induction motors:

• In the broadest sense, the major difference is in the rotor itself.  In a squirrel cage induction motor, current is induced into the rotor from the field (stator) through the air gap, and conducted through aluminum (or other material) bars, which are most often die cast in the slots of the rotor laminations.  In the case of a PMAC motor, the rotor itself contains permanent magnet material, which is either surface-mounted to the rotor laminations stack or embedded within the rotor lamination.  In either topology, electrical power is supplied through the stator windings.

The benefits of PMAC motor versus AC Induction:

• Permanent Magnet AC motors are inherently more efficient due to elimination of rotor conductor losses, lower resistance winding and “flatter” efficiency curve.  Due to their synchronous operation, PMAC motors offer more precise speed control.  PMAC motors provide higher power density due to the higher magnetic flux as compared with induction machines.  Finally, Permanent Magnet motors generally operate cooler, resulting in longer bearing and insulation life.

Permanent Magnetic VSD Screw Air Compressor