Bo Ma

Development of a New Low-Cost 3-D Flux Transverse Flux FSPMM With Soft Magnetic Composite Cores and Ferrite Magnets

In this paper, a new 3-D flux transverse flux flux switching permanent magnet machine (3-DFTFFSPMM) is proposed. The cost of this machine is very low since both the soft magnetic composite (SMC) cores and ferrite magnets are very cheap, and the performance of this machine is good due to the special designed topology. For the qualitative analysis and initial design, the simplified power equation is developed to find the optimal design, and the 3-D finite-element method is applied for the quantitative analysis. Considering it is very difficult to obtain a special ferrite magnet in the current market, the 3-DFTFFSPMM for prototyping in the workshop is improved with a new design. For the prototyping, the SMC cores are made by using the manual die compacting technology. Last, the efficiency map of these two machines is obtained to judge the operational performance.

Robust design optimization of electrical machines and drive systems for high quality mass production

Electrical drive is the heart in many modern appliances, as well as industry equipment and systems. In order to achieve the best design objectives, such as high performance and low material cost, various deterministic optimization methods have been developed for optimal design of electrical machines, power electronic converters, and parameters of control algorithms. On the other hand, the final quality of a motor drive system in mass production depends highly on the manufacturing technology employed and can be greatly affected by essential manufacturing tolerances and unavoidable uncertainties due to material diversity, machining error, and assembling inaccuracy, etc. An aggressively optimized design may be difficult to mass produce and end up with high manufacturing cost and/or high rejection rates. To solve this challenge, a robust design technique called design for six-sigma has been introduced to improve the manufacturing quality of both electrical machines and drive systems based on the multi-disciplinary, multi-level and multi-objective optimization methods. This work aims to show the development of these methods and their applications.

Design Optimization of a Permanent Magnet Claw Pole Motor With Soft Magnetic Composite Cores

In our previous study, the claw pole motor (CPM) shows promising magnetic concentrating performance for permanent magnet motors with soft magnetic composite cores. Meanwhile, its relatively complex structure also increases the core loss and cogging torque. To conduct the high dimensional optimization of the CPM with comprehensive analysis models, this paper presents an improved multilevel strategy of high efficiency. Since the holistic performances, including output torque, efficiency, cogging torque, and back electromotive force, are considered, an orthogonal design is utilized for the surrogate model building for increasing the optimization efficiency. A full factor sample method for the surrogate model is also conducted for comparison. The similar optimization results with the two kinds of models prove the effectiveness of the proposed method and optimal design.

Model predictive control of brushless doubly fed twin stator induction machine: A model reduction approach

This, paper presents a model predictive control (MPC) scheme and its model reduction approach for the brushless doubly fed twin stator induction machine (BDFTSIM). Firstly, the state-space equations of BDFTSIM, in terms of (power winding) PW flux, (rotor winding) RW flux, and (control winding) CW flux, is derived for developing the complete power model which is explicitly used to predict the future behavior. However, the MPC based on the complete model is too complicated for real time application. Therefore, a relevant model reduction approach is then developed for simplifying the power model while maintaining the accuracy under various conditions. Finally, by comparing the simulation results of the MPC based on the reduced model and complete model respectively, the effectiveness of the proposed method is verified.

Parameter analysis of a new AFIPM for light electric vehicle application

The electrical machines are gaining more and more attentions nowadays, especially for the electric vehicle application. Compared with the radial flux machine, the axial flux machine can have higher torque density and efficiency due to its tight structure. However, most of the axial flux machines are designed with the surface mounted permanent magnets (PMs) rotor, where the reluctance torque ability is reduced. To improve the torque ability of the axial flux machine, a new axial flux interior permanent magnet machine (AFIPM) is proposed and analyzed in this paper. The rotor of the proposed AFIPM is manufactured by the rolling the electrical steels as a ring core, then the PMs are inserted in the holes of the rotor ring, the axial side of the rotor ring is designed with the several different steps to eliminate the harmonics of the back EMF as well. The static performance and electromagnetic parameters of the AFIPM is calculated and it shows that the reluctance torque ability of the AFIPM is very good, based on the 3D finite element method (FEM) and frozen magnetic permeability technology.

Application-oriented design optimization of flux-switching PM motors

Flux-switching permanent magnet machines (FSPMMs) have been investigated for hybrid electric vehicles (HEVs). This paper presents an optimal FSPMM with 12 stator poles to meet the minimal performance specifications required by the drive machine in the 2010 Prius HEV. After a qualitative analysis based on size equation to briefly compare performances of FSPMMs with four rotor topology structures, a quantitative analysis method based on multilevel optimization method and finite element analysis model is presented to obtain an accurate performance comparison. It is found that FSPMMs with different topology structures have different optimal structural parameters, and the optimal one with 13 rotor poles has the best performances in terms of output power and efficiency among four different rotor structures. The proposed method can be employed as an accurate design optimization and comparison method for FSPMMs with different topology structures and highly dimensional structural optimization parameters.

Manufacturing processes of soft magnetic composite cores for permanent magnet machines

By using the low mass density compaction, the electrical machine with soft magnetic composite (SMC) cores has shown its great advantage of the low manufacturing cost over that with silicon steels, especially in the mass production. For the laboratory prototype, wire cutting method is widely used to build the SMC cores for electrical machine. However, cutting the SMC preform block can destroy the magnetic properties of the SMC material, making that the electrical machine made in the laboratory cannot have the same performance as that in the mass production. To minimize the gap between the laboratory prototype and the mass production, the SMC cores should be made by the die compaction. However, to achieve high mass density, the compact pressure must be high and the productivity is low. On the other hand, low mass density compaction would greatly increase the productivity, but the core performance may deteriorate, which can be dealt with careful design and optimization of electrical machine. This paper presents our recent investigation on the manufacturing process of soft magnetic cores. The details of designing the die tools and building the SMC cores by using these tools are described.

Development of a new low cost transverse flux-flux switching permanent magnet machine with soft magnetic composite cores and ferrite magnets

Soft magnetic composite (SMC) material is a new soft magnetic material, now it is popular in the designing of permanent magnet machine where high operation frequency and 3-D flux path required, due to its advantages of low eddy current loss and magnetic isotropy.