Research On Drive And Fault-Tolerant Control Of Dual Three-Phase Linear Flux-Switching Permanent Magnet Motor

With the continuous advancement of urbanization,in order to save building land,more and more high-rise and super high-rise buildings have been built.Due to the adoption of traction steel ropes,traditional traction elevators usually suffer from the disadvantage of limited lifting height and the difficulty of the multiple cars in one hoist way.On the contract,the advantages of direct drive elevators based on linear motor,such as theoretical unlimited lifting height,have attracted much attention.In a linear flux-switching permanent magnet（LFSPM）motor,a set of armatures winding and permanent magnets are located on the primary side,and the secondary side is only a salient pole iron core structure.When the arrangement of short primary and long secondary structure is adopted,there will be the advantages of convenient installation and low cost for the drive elevator application.In addition,compared to three-phase linear motors,multiphase linear motors have attracted widespread attention due to their high-power density,high reliability,low thrust pulsation,multiple degrees of freedom,and strong fault tolerance.In this paper,a new dual-three-phase linear flux-switching permanent magnet（DTP-LFSPM）motor is taken as the research object.The operation principle and electromagnetic characteristics are analyzed,based on which,the mathematical model,the space vector pulse width modulation（SVPWM）,and the fault-tolerant control are deeply studied.A fault-tolerant SVPWM strategy based on virtual voltage vectors is proposed to effectively improve the steady-state performance of DTP-LFSPM motors under open circuit faults.The main contents of this thesis include:（1）Combining four special rotor positions,the operation principle of DTP-LFSPM motor is analyzed,and its electromagnetic characteristics such as permanent magnet flux linkage,no-load EMF,and inductance are analyzed by finite element simulation.Then,the mathematical models in the six-phase coordinate system and the two-phase coordinate system are built,and a simulation model of DTP-LFSPM motor is built in MATLAB/SIMULINK.（2）The distribution of 64 space voltage vectors in theα-βand z₁-z₂ subspace are introduced,and the maximum two-vector SVPWM algorithm and the maximum four-vector SVPWM algorithm are analyzed in detail.Aiming at the disadvantage of the maximum four-vector SVPWM algorithm that the switching times of the inverter switching devices are not 1 within a PWM cycle,a SVPWM algorithm with the optimal switching times is studied.Its switching waveform of a PWM cycle is symmetric about the center,and the switching times are 1.Through simulation and comparison,it is found that the proposed method has a more effective harmonic suppression effect than the maximum four-vector SVPWM algorithm.（3）Aiming at single-phase and two-phase open-circuit fault of a DTP-LFSPM motor,a current hysteresis fault-tolerant control strategy based on constant magnetomotive force was studied.The residual phase currents with and without neutral point isolation are calculated with the objective functions of minimum stator copper loss and maximum output electromagnetic thrust,respectively.The correctness of the residual phase current is verified by simulation.（4）Aiming at the shortcomings of current hysteresis technology such as low voltage utilization and inability to apply in high-power applications,a fault-tolerant SVPWM strategy for dual three-phase motors based on virtual voltage vectors is proposed and applied to DTP-LFSPM motors,which can effectively improve the operating performance of the motor under single-phase open-circuit fault.（5）Finally,an experimental platform for DTP-LFSPM motors is established based on the RTU-BOX204.The experiments are carried out to test the electromagnetic performance of the motor system with the SVPWM algorithm and the fault-tolerant control strategy,thus verifying its feasibility and effectiveness.