| The in-wheel motor is not only the core component of distributed drive power system,but also the core component of intelligent chassis required by driverless technology.the axial-flux in-wheel motor with fan-shaped module is a new type of axial-flux motor with fan-shape module stator winding and integrated design of brake disc and motor rotor.When applied to passenger cars,it can effectively reduce the unsprung mass of in-wheel motor,effectively combine hydraulic braking to ensure vehicle braking safety,and avoid motion interference with existing vehicle chassis suspension parts.The application of this technology can form independent steering integrated parts of driving and braking,and can form distributed drive system and hybrid system.In the case of providing vehicle distributed driving power,it can effectively combine friction braking on the basis of electric braking to further improve the safety of vehicle braking.The main research contents of this paper are as follows:(1)The topological structure of the axial-flux in-wheel motor with fan-shaped moduleThe advantages of the distributed drive system formed by the in-wheel motor for the whole vehicle are described in detail,and the differences,advantages and disadvantages of three kinds of permanent magnet synchronous in-wheel motors with different radial,axial and transverse magnetic fields in the direction of magnetic force line and rotating shaft are deeply compared.Facing the three problems of reducing unsprung mass,retaining friction braking and adapting to suspension structure faced by the current application of traditional in-wheel motor in the whole vehicle,the topology of the axial-flux in-wheel motor with fan-shaped module is proposed.The axial-flux field in-wheel motor with fan-shaped module has high power density and compact axial structure.It has the advantages of retaining electronic brake calipers and various braking functions.It has important application value and industrialization significance in the drive and energy recovery system of new energy vehicles,the propulsion system of electric ships,the rotor drive system of manned aircraft and the robot drive system.This paper analyzes the advantages and motor configuration of axial-flux field permanent magnet synchronous in-wheel motor in detail,further classifies and compares the structures of double-sided air gap single rotor and double stator,puts forward the design and development ideas and methods of this type of motor,and puts forward the main problems and research contents.(2)Modeling and analysis of electromagnetic dynamics of fan-shaped module motorThe design and development principles and methods of in-wheel motor based on the spatial characteristics of hub structure and different suspension structures are studied.At the same time,the maximum speed,maximum outer diameter and maximum available stator thickness of inwheel motor are compared and calculated in detail according to the parameter requirements of tire adaptation speed of gear train and hub structure parameters.The calculation methods of driving and braking torque demand and speed demand of standard test cycle are studied in detail.The design boundary of electromagnetic wheel drive and motor wheel set is analyzed.The mathematical model of axial-flux permanent magnet synchronous motor is studied and analyzed.On the basis of discussing the research progress of axial-flux permanent magnet synchronous motor,the vector transformation theory,voltage torque equation and basic output characteristics of this type of motor are deduced in detail.This paper focuses on the analysis and Research on the winding structure,winding current,electromagnetic field distribution and the law and mechanism of air gap magnetic induction intensity of axial-flux permanent magnet synchronous motor,puts forward the theoretical basis of fan-shaped module axial-flux in-wheel motor,and deduces the size equation of axial-flux in-wheel motor under the new topology.The changes of electromagnetic field,power,torque,inductance and back EMF of traditional circular motor and fan-shaped module motor are analyzed and compared in detail.(3)Optimization method for reducing cogging torque and eddy current heating of fan module motorBased on the theoretical analysis,the electromagnetic field distribution and output characteristics of in-wheel motor under the given parameter target are deeply analyzed.The electromagnetic model of the inner and outer diameter neutral surface of the axial-flux field inwheel motor is established by using the two-dimensional model to analyze the magnetic field distribution and magnetic saturation.At the same time,the main parameters affecting the motor output torque and cogging torque are optimized.The three-dimensional model is used to establish the full circle double side air gap double stator and single rotor model,and further analyze the magnetic field distribution and electromagnetic characteristics of the stator core;At the same time,the fan module bilateral air gap double stator and single rotor models are established,and the changes and differences of electromagnetic parameters between the two models are deeply compared and analyzed.According to the characteristics of the motor,two innovative methods to reduce cogging torque are proposed,and the magnet skew pole is optimized.Using the optimization results,the magnetic flux line density,magnetic field strength,input and output parameters and the characteristics between torque and current of the axial-flux in-wheel motor with fan-shaped module are analyzed in detail.At the same time,the eddy current heating of rotor and magnet is analyzed and discussed,the design idea and new structure of layered magnet body to reduce eddy current loss are put forward,and the different effects of eddy current heating of the two kinds of magnets are compared.The eddy current heating of brake calipers is further analyzed,and the eddy current heating results of cast iron calipers and aluminum base calipers under different heat dissipation coefficients are compared.Combined with electromagnetic finite element analysis,the stress characteristics of bilateral stators of in-wheel motor are analyzed.At the same time,the mechanical finite element calculation and verification of stress and displacement of symmetrical stator shell and iron core under peak working conditions are carried out,and the structural optimization idea of shell is put forward.The stress distribution of stator winding support parts,hub bearing and rotor support parts are deeply analyzed.(4)Heat dissipation analysis and cooling structure optimization design of axial-flux motor with fan-shape moduleAccording to the in-depth analysis of the heat dissipation problem of in-wheel motor,this paper designs and develops the internal-external through type disc cooling structure,which is divided into series and parallel schemes according to the water channel layout.The three-dimensional electromagnetic-temperature-structure multi physical field coupling analysis model is established,the motor loss is analyzed,and the physical model of cooling structure is established.By simulating the temperature field of motor with cooling structure,the cooling effects of series and parallel schemes on motor at peak power are compared.The results show that both schemes can control the temperature of the motor working under the peak power state below the expected temperature,and the effect of the series scheme is better than that of the parallel scheme.(5)Manufacturing technology and experimental analysis of axial-flux in-wheel motor with fan-shape module.Six 27 slot 24 pole prototypes are studied and manufactured.The mechanical,electromagnetic and heat dissipation structural design of axial-flux field in-wheel motor with fan-shaped module is described.The rectangular winding design and one-time forming technology of concentrated winding axial motor with fan-shape module,the siliconizing process and experimental method of carbon-ceramic disc,and the winding forming and wire cutting process of iron core are put forward.This paper summarizes the key technologies based on the integrated manufacturing technology of carbon-ceramic rotor and brake disc,the manufacturing method of inclined pole of fan-shaped permanent magnet rotor and the permanent magnet lamination technology to reduce the loss of permanent magnet,and studies the key manufacturing integration technology and experimental characteristics of axial-flux in-wheel motor with fan-shape module from all aspects of experimental testing.The correctness of theoretical calculation and simulation analysis is verified by experimental test,which lays a solid foundation for the optimal design of the the axial-flux inwheel motor with fan-shaped module. |
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