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The 2-degree-of-freedom direct drive induction motor (2DoFDDIM) is capable of implementing rotary linear or helical motion, which has the definite advantages of integrated structure, high material utilization, and so on. In this paper, the characteristics analysis of the three kinds of motions is presented. The air-gap magnetic field distributions and mechanical characteristics of the 2DoFDDIM with three motions are derived respectively. The results show that there is super synchronous speed or velocity phenomenon for rotary or linear motion. Moreover, the coupling effects between the rotating and travelling wave magnetic fields and that between the two mechanical motions will deteriorate the performance of the three-dimensional (3-D) helical motion compared with the two-dimensional (2-D) motion (rotary or linear). The expressions of the resistant torque and force caused by the coupling effect are derived, which are verified by 3-D finite-element models (FEMs). The results regarding the weakening of the output torque of helical motion and interacting magnetic field obtained from FEMs are then verified by experimental tests. Finally, the skewed slot method is applied to 2DoFDDIM, which successfully improves the performance of helical motion aiming to compensate the coupling resistant torque and force. [ABSTRACT FROM AUTHOR]

The special structure of the two‐degrees‐of‐freedom direct drive induction motor (2DoFDDIM) gives rise to the magnetic‐coupling between the rotary and linear magnetic fields. In this article, the dynamic magnetic‐coupling effect, which is against the static coupling effect and indicates the special phenomenon caused by coupling magnetic fields in helical motion, is exposed and investigated based on the 3D finite‐element model (3D FEM). The control variable method is adopted and only the coupling magnetic field in helical motion is considered in this research. The performance changes caused by the dynamic magnetic‐coupling effect of the motor are simulated and analyzed. The relationship between the coupling magnetic field and the dynamic magnetic‐coupling effect is disclosed. To validate the 3D FEM and the magnetic‐coupling effect of 2DoFDDIM, a prototype and an experimental platform were built and measured. For the induced voltages caused by the magnetic‐coupling effect, the finite element analysis results are in agreement with the experimental results. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In this work, a novel solid rotor induction motor with toroidal winding (N-TWSRIM) is proposed and its structure and main structural parameters are given. The operating principle is analyzed in accordance with the movement of the armature magnetic field at different times. An equivalent circuit model (ECM) of the N-TWSRIM is established based on composite multilayer theory to analyze and calculate motor performance quickly and accurately. Electromagnetic performance, which includes output torque, stator current, and power factor under different slip, is calculated with ECM, and its results are compared with those of the finite element method. A prototype of the N-TWSRIM is built and experimented on to validate the correctness of the operating principle and ECM. Experimental results on stator current and torque are consistent with the finite element and analytical results. [ABSTRACT FROM AUTHOR]

In this paper, the characteristics of the helical motion of the rotatory-linear 2-degree-of-freedom split-stator induction motor (2DoFSSIM) are investigated, which cannot be regarded as the simple superimposition of the 1DoF rotary and linear motions. A set of torque and force equations of the helical motion is deduced. It illustrates that the interacting electromagnetic torque and force are opposite to the directions of rotary and axial movements, respectively. For the rotating movement, the interacting torque is related to the axial velocity. Moreover, the axial velocity significantly influences the output torque performances and no-load speed. Similar conclusions can be obtained for axial movement of the helical motion. The 3-D finite-element method is applied to calculate the exact output performance considering the interacting influence. Furthermore, the prototype machine is manufactured and tested to verify the analytical results. [ABSTRACT FROM AUTHOR]

In this paper, a modified equivalent circuit model (ECM), which considers the effects of an arc-shaped stator structure and saturation, is presented to calculate the characteristics of a two-degree-of-freedom direct drive induction motor (2DoFDDIM). The motor has a novel slotted solid rotor (SSR), which is slotted along the axial and circumferential directions, and copper is cast in the slots. The SSR is equivalent to a cage rotor by analyzing the current distribution using the circuit diagram. The corrected ECM parameter expressions of a cage rotor are proposed to calculate the SSR parameters. The characteristics obtained by ECM and finite element method are compared to verify the accuracy of the modified ECM. This paper provides reference for calculating the parameters of the induction motor with SSR. [ABSTRACT FROM AUTHOR]

A two degrees of freedom (2-DOF) actuator capable of producing linear translation, rotary motion, or helical motion would be a desirable asset to the fields of machine tools, robotics, and various apparatuses. In this paper, a novel 2-DOF split-stator induction motor was proposed and electromagnetic structure parameters of the motor were designed and optimized. The feature of the direct-drive 2-DOF induction motor lies in its solid mover arrangement. In order to study the complex distribution of the eddy current field on the ferromagnetic cylinder mover and the motor's operating characteristics, the mathematical model of the proposed motor was established, and characteristics of the motor were analyzed by adopting the permeation depth method (PDM) and finite element method (FEM). The analytical and numerical results from motor simulation clearly show a correlation between the PDM and FEM models. This may be considered as a fair justification for the proposed machine and design tools. [ABSTRACT FROM AUTHOR]