Design And Analysis Of A Nine-phase Flux-switching Permanent Magnet Machine For Wind Power Generation

With ever increasing concerns on environmental protection and energy crisis,sustainable energy such as wind power is often recognized as one of promising solutions for these problems.Multiple-phase permanent magnet(PM)machines have been considered as the candidate generators in wind power system since it offers considerable merits of high torque density,high efficiency,high fault-tolerance ability and low torque ripple.By incorporating the concept of high-torque-density high-fault-tolerance stator-excited PM machine in nine phase PM machines,this thesis proposes a nine-phase flux-switching permanent-magnet(NPFSPM)machine.By utilizing finite element analysis(FEA),the configuration and electromagnetic performances of proposed machine are analyzed and discussed.In addition,the optimal design of proposed machine is conducted and evaluated.Finally a prototype is manufactured and experimental research is carried out for the validation.The main research content of this thesis can be summarized as follows:1.In this thesis,a new nine-phase flux-switching permanent-magnet generator is proposed.By using finite element analysis,the basic configuration and operation principle of proposed machine are analyzed and discussed,hence properly determining the winding connection type of proposed machine.In addition,the magnetomotive force harmonics of nine-phase winding are evaluated.And,the comparative study among proposed machine with different teeth-slot ratios is conducted,by which the optimal slo/pole ratio is determined.2.The power equation of proposed machine is mathematically deduced,obtaining the initial dimensions of proposed machine.From the perspective of PM utilization and machine torque density,the single-parameter sweep of proposed machine is carried out to determine the variation range of design parameter.In order to further reduce machine cogging torque,reduce machine loss and improve machine torque output,the multi-objective optimization is carried out to determine the final configuration of the proposed NPFSPM machine.Based on the optimization results,a 10 k W prototype machine is manufactured for validation.3.By using 2D finite element analysis,the electromagnetic performances of proposed machine are simulated and analyzed including field distribution,air-gap flux density,no-load PM flux linkage,no-load electromotive force(EMF),phase inductance,cogging torque and electromagnetic torque.Meanwhile by using 3D finite element analysis,the end effects of proposed machine are also evaluated,hence optimally designing the design specifications of proposed machine.In order to verify the reasonablilty and the effectiveness of the proposed design method,the key parameters of prototype including inner power factor angle and voltage regulation rate are calculated by using transient co-simulation.Hence the no-load test and load test are carried out on the NPFSPM machine test bed for validating the theoretical analysis.4.Two fault-tolerance control strategies,which are aiming to achieve minimum copper loss and control variable respectively,are proposed for the NPFSPM machine with the fault of armature winding open.In addition,four different topologies of fault-tolerance NPFSPM machines,namely the configurations of 36slots/34 poles with fault tolerant teeth,36slots/34 poles with single-layer winding connection(including two kinds of connections),36slots/35 poles with single-layer winding connection respectively,are proposed and analyzed.The steady-state performance and limitation on the short-circuit currents of proposed four machines are further simulated and discussed.5.According to basic electromagnetic laws and operation principle of NPFSPM machine,the mathematical model of proposed machine is derived under nine-phase stationary coordinate system and two-phase rotating coordinate system respectively.By combining the mathematical deduction and finite element analysis,the simulated direct-drive wind power system,in which the DC machine acts as wind turbine and proposed machine works as the generator,is developed based on MATLAB/SIMULINK.Moreover,the operation characteristics and maximum power point tracking control strategy of proposed wind power system are simulated and evaluated.6.The NPFSPM machine test platform is also established.Both the hardware circuit and software program based on Dspace1005 controller for system experiments have been designed.And the no-load and load test have been carried out,and the results have verified the accuracy and effectiveness of the machine design theory and FEA.Then,in order to realize the maximum wind power tracking control,the multiple-dimension space voltage vector control strategy based on optimum torque feedback method is implemented,in which the steady-state and dynamic performances of the power generating system are researched.Therefore,the effectiveness of the proposed control strategy has been proved.