TORQUE PREDICTION USING THE FLUX-MMF DIAGRAM IN AC, DC, AND RELUCTANCE MOTORS

This paper uses the flux-MMF diagram to compare and contrast the torqu e production mechanism in seven common types of electric motor. The fl ux-mmf diagram is a generalized version of the flux-linkage versus cur rent (psi-i) diagram for switched-reluctance motors. It is illustrated for switched-reluctance, synchronous-reluctance, induction, brushless ac, brushless dc, interior PM and dc commutator motors. The calculate d flux-MMF diagrams for motors with the same electromagnetic volume, a irgap, slotfill, and total copper loss are shown and are used to compa re the low-speed torque and torque ripple performance. The motor desig ns used were reasonably optimized using a combination of commercially available motor CAD packages and finite-element analysis.