A Vector-Signal-Based Analysis for Salient Synchronous Motors Oriented to Energy-Efficient Current Controls

Abstract

This paper consists of two main parts. The first part newly proposes a basically and commonly important mathematical model in new closed form for synchronous motors of salient pole characteristics, which indicates with clear physical meaning motor dynamics, torque generation relation and energy transfer relation in general frame. The second part extends the former model-based analytical results to the analysis of energy-efficient but desired-torque-producing current controls such as minimum current control, unity power factor current control and maximum power factor current control. New analytical methods for generating current command in real time based on torque command are given, which are essential for realizing these attractive energy-efficient control schemes. Interesting phenomena of interior states of motors occurring during the controls are also newly clarified. Analysis with clear physical meaning is carried out in general frame and most of the results are new.