Abstract
In order to avoid the unsafe operation and raise efficiency of yokeless and segmented armature axial flux motors at high speed, the control current of air gap flux is expected to be as small as possible with the same field-weakening effect. To reduce the control complexity, a new structure of module poles with a combination of permanent magnet and soft magnetic material is proposed, which has the characteristics of lower d-axis reluctance and a higher performance of yokeless and segmented armature axial flux motor with surface mounted permanent magnet. According to finite element analysis (FEA), the flux distributions of a rotor pole in no-load and demagnetization condition are contrasted, and under this new configuration, the derivative analytical models of back electromotive-force (EMF), electromagnetic torque, and air gap flux are validated, moreover, the influence of soft magnetic material of rotor poles on controlling the air gap flux is investigated in different load. Based on a particular objective function, the combination of permanent magnet and soft magnetic material is optimized. The results show that optimal solution of field-weakening performance of yokeless and segmented armature axial flux motors can be improved effectively and legitimately.
Highlights
During recent years, the rising cost of energy and environmental issues have encouraged researchers to investigate techniques for increasing the efficiency of electric drives
The technology of yokeless and segmented armature axial flux motors was developed for the electric vehicles to solve those economic and technological problems, besides, because of its superior performance, it can be applied to many fields such as renewable energy sources and flywheel energy storage, and it can be designed as a high pole machine for low-speed energy systems, such as wind and hydro generators [1,2,3]
This paper proposes a new type of yokeless and segmented armature axial flux motor with modular poles, replacing a part of the permanent magnetic material with a soft magnetic material with the shape of rotor poles remaining unaltered
Summary
The rising cost of energy and environmental issues have encouraged researchers to investigate techniques for increasing the efficiency of electric drives. The new structure of stators plays an important role in improving of power density and efficiency and it simplify the manufacturing process of yokeless and segmented armature axial flux motor, which makes it an ideal design for electric vehicles [4]. The above researches are limited to traditional AFPM motors without any analysis of the field-weakening capability of yokeless and segmented armature axial flux motors and a quantitative analytical calculation of back EMF, torque and air gap flux. This paper proposes a new type of yokeless and segmented armature axial flux motor with modular poles, replacing a part of the permanent magnetic material with a soft magnetic material with the shape of rotor poles remaining unaltered. After weighing the output performance and field-weakening performance, the optimal value of the objective function is obtained, which can maximize airgap flux control ability
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