Primary Design Considerations - Synchronous Reluctance Motor

PRIMARY 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 PF_max of a synchronous reluctance machine given as

PF_max = L_d/L_q - 1/ L_d/L_q + 1

Higher L_d/L_q 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 +ω²L_dL_q)² { Rs² + Rs ω(L_d-L_q) sin 2Ȣ }+ω² [L_d²+L_q²/2 – L_q² – L_d²/2 cos 2Ȣ ]

Where

Rs – Stator resistance

L_{d  ,}L_q - 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.