Most pumps and fans operating in commercial and industrial applications are driven by AC induction motors. “ACIM”, which stands for “alternating electric current induction motor”, is an asynchronous type of motor that permanent magnet synchronous motor depends on electric current to turn the rotor. Torque can be produced by electric current in the rotor. The electric energy is generated through electromagnetic induction from the magnetic field of the 
stator windings. Within an ACIM, the rotor generally rotates at a lesser speed compared to the magnetic field. A “PMSM”, which means “permanent magnet synchronous engine”, depends on magnets to turn the rotor, which spins at the same rate as the PMSM’s internal rotating magnetic field.
There are some key differences among AC induction Motors and Permanent Magnet Synchronous Motors.