Novel analytical theory for vector controlled interior permanent magnetic synchronous machine drives

A novel approach for operation analysis of an IPM-SM has been described. To draw the vector diagram under adjustable speed operation, the concept of normalized voltage was introduced. It is to divide the voltage value by angular frequency of the machine, then the voltage vectors, which contain angular frequency immenently, will not change their length under adjustable speed operation, and the vector diagram will keep its size unchanged for the whole speed range. Also, reactance drop locus and its accompanying yardstick circle for determining current phase angle, in corresponding to the variation of the given armature current vector, were deduced. Then, the operation of the machine for the whole adjustable speed range can be represented in single diagram. As the accompanying matters, the methods for calculating the operating characteristics of maximum torque control and 100% power factor control were shown.