Study Of Analysis, Design And Control On Novel Flux Switching Motor System

Flux Switching Motor (FSM) is a novel brushless double salient motor emerging in recent years. It has the same structure as SRM which has neither winding nor PM in the rotor. FSM has the advantages of rugged structure, easy manufacture and low cost, it is also suitable to operate at extreme high speed and adverse condition. The windings in FSM are electrified all the time as it works. Compared to SRM, FSM has higher copper-utilize ratio and require less kVA of the power converter because the excitation current component and armature current component has been separated absolutely. The vibration and noise of the motor are reduced by the unique operational electrified pattern, thus FSM has been seen as a good potential candidate drive system in the future. Flux weaken control can be easily achieved because the field current can be controlled when FSM is operated as a generator.FSM has the advantages of low cost and simple control strategies because only the armature winding require controlled. It has high efficiency and very good speed-adjust performance which is very like traditional DC motors. FSM has found more and more applications in household appliance, power tools and automotive appliance.FSM is an electromagnetic appliance with complicated nonlinear characteristics. It has obvious edge and local saturation effect which is the same as other double salient motors. In addition, FSM generates electromagnetic torque depending on the closed-coupled field and armature winding. As FSM works, all the windings in stator are electrified all the time, the DC magnetic field generated by field winding and the AC magnetic field generated by armature winding are closed coupled. Hence, the edge and saturation effect are more strategic with respect to the other double salient motors. FSM is a complicated electromagnetic appliance with unique nonlinear, variable structure and close coupled characteristics.The present research scope and depth which the experts and scholars deal with is very limited due to the short period during which FSM has been studied. In view of this, this paper studied FSM system with the emphasis of operation principle, mathematic model, performance analysis, electromagnetic parameters calculation, magnetic field analysis, dynamic simulation, machine design and control. A prototype motor was trial-manufactured to validate the theoretical analysis. The power converter and position detecting appliance of FSM was developed. The main contents of this paper are as follows:(1) Chapter 2 studied the operation principle, electrified pattern and electromagnetic characteristics of FSM, then illustrated the nonlinear, variable structure and close coupled characteristics. Based on Maxwell 2D, the magnetic field and electromagnetic parameters of FSM are calculated and analyzed. The work of this part provided a good reference to the knowledge of FSM.(2) Normal nonlinear method which was used to analyze the double salient motors can not describe the unique nonlinear, variable structure and close coupled characteristics of FSM. In order to overcome the problems of simulation and modeling of FSM, this paper established the high rank continuous nonlinear inductance function of FSM. Based on this model and hybrid means of modeling, the Simulink model of FSM involving the machine and whole control system were established. Then the numerical simulation were performed and the results were compared to that obtained by Time stepped Element Method (TSFE).(3) In chapter 5, the nonlinear variable structure equivalent magnetic circuit model was proposed which can describe the detailed poly phase coupling and nonlinear characteristics of FSM. The analytical expressions of permeability in the air gap and iron core are deduced. During the calculation, the iteration and convergence process was studied and a method to determine the iteration coefficients is proposed to save the calculation time. The work of this part provides a powerful tool for the electromagnetic calculation of FSM.(4) In chapter 6, a novel numerical solving method aiming to simulate the dynamic performance of FSM rapidly and accurately was proposed based on modified Forward Euler method. This method set up the status equations of FSM by matrix re-transforming and advanced the modified forward Euler equation to the FSM dynamic performance calculation which faced the difficulties of differential inversion. The method has the merits of simple process and rapidity calculation. At last, the method above was employed to calculate the dynamic performance of FSM. The calculation results were compared to that obtained by four order Runge-Kutta method and TSFE, respectively. The work of this part provided a new effective approach to the dynamic performance calculation of FSM.(5) In chapter 7, the starting performance of FSM was studied and a variety of strategies focused on reducing the dead zone of starting were discussed. Some conclusions were drawn. At last, the approach for solving the starting problem of FSM was given.(6) In chapter 7, the equation of universal output power which was directly related to motor dimensions was deduced and the method to determine the stack length and number of coils was given. The iteration calculation process of machine design was proposed. The optical rotor position detecting appliance and power converter of FSM were designed and developed. The experiment was implemented to study the performance of the prototype motor.(7) In chapter 8, the cogging torque in PMFSM was studied particularly. The detailed structure and principle of PMFSM are different from traditional PM motors and the principle, characteristics of cogging torque in PMFSM are also very different from traditional PM motors. This paper proposed an analytical theory for analyzing and calculating the cogging torque in PMFSM. Based on this theory, the analytical model of cogging torque which was directly related to the design parameters of PMFSM was deduced and employed to study the approaches to reducing cogging toque in PMFSM. At last, the detailed approach for reducing cogging torque was given which has important instructive significance to engineering practice in designing high performance PMFSM. (8) In chapter 9, a novel Hybrid Excitation Flux Switching Motor (HEFSM) was proposed and studied. FSM with electrified excitation has drawbacks of high level field current and high copper loss which limit the efficiency increasing. PMFSM has very narrow speed-adjustment range as a result of the uncontrolled magnetic motive force in PM as a motor. Besides, it is hard to adjust the output voltage when PMFSM work as a generator. Aiming at the drawbacks of present patterns of FSM, this paper proposed a novel Hybrid Excitation Flux Switching Motor. In HEFSM, the PMs were housed in the stator at special way. The magnetic field were generated both by PMs and armature winding, the speed-adjustment range could be widened by this proposed structure. HEFSM combined the merits of FSM with electrified excitation and PMFSM. The work in this part explored a new research frontier for FSM.