We perform the analysis and control of synchronous reluctance motors. Complete mathematical models of synchronous reluctance motors in the machine and in the quadrature, direct and zero variables are developed. In particular, nonlinear differential equations are found. Using these mathematical models, nonlinear controllers are designed to guarantee robust tracking and stability, attain disturbance rejection and desired accuracy. A 40 kW, 100 N-m high-speed synchronous reluctance motor, controlled by a high-performance voltage-fed converter, was designed, built, and tested by the Allison Transmission and Purdue University Indianapolis. Experimental results are reported.