This paper describes the design of high-efficiency, electronically commutated, permanent-magnet machine (ECPM) drives based on the finite element/difference method, and the solution of the ensuing differential equations with the Simulation Program with Integrated Circuit Emphasis (SPICE). The permanent-magnet motor model includes the computation of load-dependent components of the motor equivalent circuit (e.g., induced voltages and inductances). A new SPICE Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET) model reflecting the reverse-recovery current phenomenon -which is very important for the design of variable-speed drives operating in pulse-width-modulated (PWM) mode- is introduced. Results of this new model are compared with measurements. Since ECPMs lend themselves well to vehicle propulsion due to their inherent high efficiencies at light weight, it is desirable to have a very high output-power to weight ratio for such applications. In addition high ECPM drive efficiencies are important for recovering of the braking energy.