RIMARY DESIGN CONSIDERATIONS
v High output power capability.
v Ability of the rotor to with stand high speeds.
v Negligible zero torque spinning losses.
v High reliability.
v High efficiency.
v Low cost.
(a) Power factor:
The maximum achievable power factor PFmax of a synchronous reluctance machine given as
PFmax = Ld/Lq - 1/ Ld/Lq + 1
Higher Ld/Lq ratio yield higher power factors, which corresponds to reduced I2R losses and reduced volt ampere ratings of the inverter driving the machine.
(b) Copper loss and core loss:
Copper loss = 3 I2Rs
= 3V2Rs/(Rs2 +ω2LdLq)2 { Rs2 + Rs ω(Ld-Lq) sin 2Ȣ }+ω2 [Ld2+Lq2/2 – Lq2 – Ld2/2 cos 2Ȣ ]
Where
Rs – Stator resistance
Ld ,Lq - direct and quadrature inductance
The core losses are calculated corresponding to the fundamental component of flux density in the stator iron core. There will also be significant core losses in the stator and rotor due to the winding and slot harmonics. The losses are difficult to estimate reliably.
