Control of Surface Mounted Permanent Magnet Motors with Special Application to Fractional-Slot Motors with Concentrated Windings

摘要

A 30 pole, 6 kW, and 6000 maximum revolutions per minute (rpm) prototype of the permanent magnet synchronous motor (PMSM) with fractional-slot concentrated windings (FSCW) has been designed, built, and tested at the University of Wisconsin at Madison (UWM). This machine has significantly more inductance than that of regular PMSMs. The prototype was delivered in April 2006 to the Oak Ridge National Laboratory (ORNL) for testing and development of a controller that will achieve maximum efficiency. In advance of the test/control development effort, ORNL has used the PMSM models developed over a number of previous studies to study how steady state performance of high inductance PMSM machines relates to control issues. This report documents the results of this research. The amount of inductance that enables the motor to achieve infinite constant power speed ratio (CPSR) is given by L(sub (infinity)) = E(sub b)/(Omega)(sub b)I(sub R), where E(sub b) is the root-mean square (rms) magnitude of the line-to-neutral back-electromotive force (emf) at base speed, (Omega)(sub b) is the base speed in electrical radians per second, and I(sub R) is the rms current rating of the motor windings. The prototype machine that was delivered to ORNL has about 1.5 times as much inductance as a typical PMSM with distributed integral slot windings.