| Industrial robots are special robotic systems used in industrial production and are a vital component of modern intelligent factories.Generally,an industrial robot is composed of kinematic structure,gearbox,electric drive,sensor,and controller,etc.The electric drive serves as the executive mechanism by which the mechanical arms are driven with an electric machine as the energy source,to achieve the output of torque and trajectory.Therefore,the electric machine becomes the vital component of the industrial robot,and its performance to a certain extent restricts the performance of the industrial robot system.Permanent magnet synchronous machine(PMSM)is the most promising and widely used in the electric drives of industrial robots due to its advantages of high efficiency and high power density.However,along with the rapid development of automated manufacturing,the technical requirements for industrial robots are also being stricter.Thus,the electric drive components of industrial robots are facing increasingly demanding requirements,including miniaturization,high dynamics,low torque ripple,and high functional reliability.In order to deal with above issues,it is significant to develop innovative topologies of PMSM that satisfy the requirements for high-performance electric drive of industrial robots.As a novel structure of PMSM,transverse flux permanent magnet synchronous machine(TFPMSM)combines the advantages of intrinsically high torque density,the ability to adjust the electromagnetic load independently,flexible structure design,and simple winding structure,enabling it with significant potential for being used as a PMSM in industrial robot applications.In TFPMSMs,a multiphase winding structure can be utilized to enhance the fault tolerant ability,which can further improve the functional reliability of the electric drive in industrial robots.However,the existing research on TFPMSM and fault tolerant multiphase machines still have shortcomings and limitations,which hinder their application in the context of this thesis.These limitations are mainly manifested in the following aspects:(1)Conventional TFPMSM is characterized by complex structural designs and unique performance characteristics that limit the release of its kinds of advanced potentials in industrial robot electric drives.(2)TFPMSM commonly experiences large torque ripple,which conflicts with the need for smooth torque output in industrial robot electric drives.(3)The traditional analytical calculation methods of electric machines are no longer applicable to TFPMSM due to its three-dimensional magnetic circuit structure,and three-dimensional model for finite element analysis needs to be established,which means that considerable computing resources and time will be consumed.(4)In terms of the existing research on fault tolerant control of multiphase machines,the accuracy and complexity of control method under fault condition conflict with each other increasing the challenge of implementing fault tolerant control for multiphase machines;(5)The existing fault-tolerant control methods for multiphase machines only exhibit superior performance at low speeds,which limits the dynamic response capability of industrial robots under fault conditions.This thesis aims to investigate the design,analysis,and optimization of TFPMSMs for industrial robot applications,including its multiphase designs and fault-tolerant control methods to address the aforementioned issues.The main research contents of this thesis are as follows:1.A novel double-stator topology TFPMSM combined with hybrid stator core and disktype rotor(DS-HSDR-TFPMSM)is proposed which makes full use of the performance advantages of laminated silicon steel sheet and soft magnetic composite material.Its structural and electromagnetic design is proceeded.Firstly,the operation principle and the superiorities of DS-HSDR-TFPMSM are described.Then,the basic sizing equation are derived and the dimension parameters are analyzed.Finally,a fault tolerant design based on the dual threephase winding structure is studied for the proposed electric machine to improve its functional reliability.2.For the complex three-dimensional structure of DS-HSDR-TFPMSM,the air-gap magnetic field and performance calculation are studied using the Schwarz-Christoffel transformation-based analysis method.Firstly,a two-dimensional equivalent analytical model of DS-HSDR-TFPMSM is established.Then,its simplified analytical model obtained by the Schwarz-Christoffel transformation is derived.Finally,the air-gap magnetic field distribution of the electric machine is derived by Hague’s equations which is used to calculate the performances of machine furtherly.Above results are all compared with the calculation results obtained by finite element method(FEM)to validate the accuracy of proposed SchwarzChristoffel transformation-based method.3.The research on optimization design of DS-HSDR-TFPMSM is conducted based on the BP neural network and multi-objective optimization algorithm.Firstly,a novel optimization design method for electric machine is proposed based on BP neural network and multi-objective optimization algorithm.Then,DS-HSDR-TFPMSM is optimized through the steps of optimization problem description,sample space design,neural network modeling,and multiobjective particle swarm optimization.Finally,optimization design results are validated by the FEM.4.Based on the accessible fault tolerant designs of DS-HSDR-TFPMSM,the fault tolerant control technique of the dual three-phase DS-HSDR-TFPMSM under the normal decoupled frame is investigated.Firstly,a fault tolerant control method is proposed,which reconfigures the reference current in the normal decoupled frame based on the principle of minimum copper loss or maximum torque operation range according to different optimization objectives under fault condition.The fault tolerant vector control model is obtained by modifying the current strategy based on the normal control model.Then,the fault tolerant control method under highspeed condition is investigated,in which the harmonic components in the reference current under high speed are tracked and controlled by using a multi-reference frame-based method and a proportional-resonant controller-based method.5.The prototype machine is manufactured and researched by experiment.Firstly,DSHSDR-TFPMSM is researched in terms of the manufacturing as well as assembly process,and validation of its structural strength.Then,the experimental platform for DS-HSDR-TFPMSM prototype and a commercialized general radial flux permanent magnet synchronous machine with the same power rating are constructed to validate the performance of DS-HSDR-TFPMSM. |
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