Analysis And Optimization Of Large Transverse Flux Permanent Magnet Machine With Flux-concentrated Design

As a product involved in material science, power electronics and electrical engineering, rare-earth permanent magnet machine is arguably the most important category of electrical machine for a wide spectrum of application. Most of the major developments in recent times have been in new machine topologies and control methods. Especially the emergence of transverse flux permanent magnet machine (TFPM), a new phase of electrical machine design and power electronic converter has evolving. TFPM has becoming a superior choice for low speed, high torque and direct electric propulsion applications. Compared to conventional machine, TFPM hasn't noticeable predominance in small dimension for their complicated configurations. The principal advantage of TFPM topology is that for large diameter, multi-pole and multi-phase forms. This dissertation mainly focuses on analysis and optimization of large TFPM with flux-concentrated design.Firstly, a novel 10.4MW TFPM with double C-shaped stator core and concentrating flux rotor is developed. The stator core is characterized with combined configurations including outer stator, inner stator and joint stator, which allows for an easy assembly and low manufacture cost. This unique idea of this new configuration has applied and granted a patent. In addition, a special insulated ring is designed to keep from electromagnetic couple between stators, which also guarantees the mechanical intensity and positional veracity. Both magnetic circuit and mechanical construction were subject to optimization. For manufacture limitations of large TFPM, there are two prototypes rated in 200W and 4.5kW have been produced in our group.Secondly, the TFPM has a complex three-dimension (3D) flux pattern where the magnetic flux passes radially, axially and circumferentially from the rotor to the stator. A 3D equivalent magnetic network (3DEMN) method suitable for 3D electromagnetic analysis especially for transverse flux magnetic systems is introduced. Assuming the current winding as virtual permanent magnet, the scalar magnetic potential equation can be satisfied in 3DEMN, which simplifies the calculation procedure and saves time greatly than vector potential.Thirdly, the static magnetic field distribution is analyzed by 3DFEM along with the magnetic force at different operational conditions such as different dimensions, different rotor positions and different loads. It is also noted that for the competition for space between the electric and magnetic circuits present in radial and axial flux machines is largely removed, the ability to load both these circuits to extreme levels brings a consequent much reduced power factor.Fourthly, as a new comer to electrical machine, optimal design of TFPM provides both design quality improvement and time saving advantage. Based on the heuristic evolutionary strategy standard particle swarm optimization (SPSO) algorithm, an improved particle swarm optimization (IPSO) algorithm is proposed and initially introduced to TFPM design procedure. The optimization goal, the minimum magnet material and machine volume approaches given in which insure the electric characteristics is available.Fifthly, with a mass of high energetic permanent magnet in TFPM rotor, the cogging torque with higher frequency can result in many problems such as mechanical vibration, noise and so on. The electromagnetic analysis results illustrate how constructional changes can decrease the torque ripple of TFPM. Harmonic content of torque waveform can be minimized by superposition technique with a suitable arrangement of individual phases.Finally, a simulation experiment is carried out. A non-linear dynamic mathematical model of TFPM is established and the corresponding digital simulation model is built on the developing platform of Simulink. The steady state and dynamic performance of TFPM are simulated under the different commutation modes. The feasibility of TFPM with superposition technique as well as full bridge power supply is verified by simulation results on the basis of improvement of resultant torque ripple and the simplification of the control.