Download permanent magnet synchronous motor

PERMANENT MAGNET SYNCHRONOUS
MOTOR DRIVES (PMSM)
PERMANENT MAGNET SYNCHRONOUS MOTOR
• The notation for PMSM is PMAC
• In PMSM the D.C field winding of the rotor is replaced by Permanent Magnets
• Permanent Magnet Materials: Alnico, Cobalt-Samarium, Ferrite.
Advantages:
• Elimination of field copper loss.
• Higher power density.
• Lower rotor inertia.
• More robust construction of motor.
• Higher efficiency.
Disadvantages :
 Loss of flexibility of field flux control.
 Remagnetization effect.
 Higher costs.
Application:
 Low power range motors are widely used in industries.
Types Permanent Magnet
Synchronous motors
1.Surface Mounted-PMSM
 Projecting type
 Inset type
2.Interioror Buried-PMSM
Types of Permanent Magnet
Synchronous motors
1.Surface Mounted-PMSM
 Projecting type
 Inset type
2.Interioror Buried-PMSM
Types of Permanent Magnet
Synchronous motors
Based on nature of voltage induced in the stator
classified as
Sinusoid ally excited PMAC:
• Stator has distributed winding.
• Stator induced voltage has sinusoidal waveform.
Trapezoid ally excited PMAC:
• Stator has concentrated winding.
• Stator induced voltage has trapezoidal waveform.
Speed control of sinusoidal PMAC
• The speed of the PMAC motor is controlled by feeding
them from variable frequency ,voltage and current.
• They are operated in self controlled mode.
• In closed loop control ,current regulated VSI is used.
• The inverter is operated to supply motor three phase
currents of the magnitude and phase commanded by
reference currents isa,isb and isc which generated by a
reference current generator.
• The stator current templates for the three phases are
generated by the rotor position sensors in such a way
that δ = π/2
Speed control of sinusoidal PMAC
Sinusoidally excited PMAC
Trapezoid ally excited PMAC
Speed control of Trapezoidal
PMAC
• According to the torque equation torque is
proportional to Id.
• Regenerative braking mode operation is
obtained by reversing phase currents.
• This will also reverse the source current
Id.
• Now power flow from the machine to
inverter and from inverter to dc source.
Speed control of Trapezoidal PMAC
Trapezoidally excited PMAC