ABSTRACT
Neodymium and cobalt-samarium magnets are widely used in the permanent magnet synchronous motors (PMSMs). They have very suitable properties for motor use; high remnant (residual) flux density and high resilience against demagnetization threat. Since the field winding is replaced by PMs, the PMSMs have low rotor inertia and high power density. Further, since there is no secondary copper loss, the PMSMs have a higher efficiency than IMs. In addition, PMSMs are more favorable in incorporating the reluctance torque especially in the field weakening region. As a result, PMSMs have a wide constant power speed range (CPSR). Because of such advantages, PMSMs are popularly used in industrial drives, home appliances, and electrical vehicles (EV). Fig. 6.1 shows a taxonomy of AC motors. They are classified by the synchronism and the structure.
