Research On Doubly Salient Hybrid Excitation Machine

In this dissertation, the basic theory and performance of parallel structrue doubly salient hybrid excitation (DSHE) machine is presented. The basic configuration, principle, and characteristics of doubly salient permanent magnet (DSPM) machine, doubly salient electro-magnet (DSEM) machine, and DSHE machine is first reviewed. The main topics include the basic structure and operating principle of DSHE machine, the basic perforance of DSHE generator, and the basic performance of DSHE motor.First, the configuration and the basic principle of this machine is analyzed. The physical model is established according to the theroy of circuit and the theory of magnetics. And the relationship between the basic parameters and length ratio of two parts is deduced. Through two-dimensional finite element analysis(FEA), the static characteristics of DSHE machine is given, including magnetic linkage, electro-magnetic force and inductor characteristics. Also, the actual equivalent inductance characteristics under generator and motor state are given. Combining the modeling of magnetic field, the armature reaction of the doubly salient machine is analyzed. The comparison of armature reaction under generator and motor state is given. And the comparison of armature reaction in DSPM machine and DSEM machine is given. Also, the influence of length ratio on static characteristics is concluded.Doubly salient brushless dc generator under different exciting schemes is proposed. And three generation strategies are presented, and they are switched reluctance generation strategy, and two kinds of doubly salient geneation strategies. The working principles of three generation strategies are analyzed. The commutation overlap and armature reaction under different schemes are introduced. The working modes under doubly salient generation strategy is especially analyzed, and the influences of excitation current, rotor speed, load characteristics and load current level on commutaion overlap are concluded. The differences about current regions and influences of armature reactions are given. Based on the above analysis, the no-load output voltage characteristics, curve of ouput voltage versus output current, short-circuit characteristics, and curve of excitation current versus output current are given. Also, for two kinds of rotor structures, the characteristics comparions under three generation strategies are given. The characteristics of DSHE machine with the variation of length ratio between two parts are concluded. And the special generator-motor mode under negative excitation current is analyzed.The doubly salient brushless dc motor under different exciting schemes is given. According to the characteristics of electro-magnetic force of skewed rotor doubly salient motor, three-phase six-state conduction mode is applied in the working of doubly salient motor, and the control modes under two kinds of rotor structures are compared. Under single-chop hysterisis current control method, theoretical analysis of working principles reveals that the phase that should have no current will appear current tails, which are positive winding currents for two time regions. The influence of current tails on motor performance is illustrated. Thus, the comprehensive working principles including commutation and current tail are given. A more accurate analysis method on working modes is proposed, simultaneously considering the winding terminal voltage and the conducting power device as state parameters. A novel adjustment method, named as coarse-adjustment under generator state and trim-adjustment under motor state is proposed. Also, the basic characteristics, including curve of torque versus current, curve of torque versus rotor speed, speed regulation characteristics, and overall efficiency is tested. Finally, the special motor-generator mode under negative excitation current is analyzed.