• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.682-684
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• 2015

A 12/14 bearingless switched reluctance motor (BLSRM) with hybrid stator poles has been proposed due to the outstanding decoupling characteristics between the torque and suspending force. However, the motor is a two-phase motor. The output torque of the motor has torque dead zone and high torque ripple. Hence, the motor cannot self-start at some rotor positions. To solve the self-starting problems and reduce the torque ripple, a stepped rotor is proposed in this paper. Then, the motor with the stepped rotor is optimally designed. In the new designed motor, the majority parameters are kept the same with those of original motor; only the torque pole arc and rotor pole shape are optimally designed. The characteristics of the redesigned motor, such as inductance, torque and suspending force, are analyzed and compared with those in the original motor. Finally, the effectiveness of the proposed method is verified by the simulation results.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.629-631
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• 2000

This paper deals with the design of a inner rotor type Brushless DC (BLDC) motor for Electric Power Steering to reduce the cogging torque. The effect of the design parameters on the characteristic and cogging torque is analyzed by Finite Element Method (FEM). The considered design parameters are as follows : the number of pole and slot. dead-zone and skew angle. and teeth shape. The winding resistance of each motor is calculated and the characteristic curve is derived from considering reactance drop voltage for original model.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1489-1494
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• 2003

A neuromuscular control system of a myoelectric prosthetic hand (PH) constitutes a nonlinear system with a dead zone whose magnitude is equal to its joint angle when the PH just grasps an object. This is because the neuromuscular control system remains an open-loop system until the PH grasps the object but it constitutes a feedback control system after the PH griped the object in which a torque induced in the fingers of the PH is fed back. To improve the transient performance of the control system, it is desirable to make the feed-forward gain as large as possible, so long as the stability of the system is not impaired. It is also desired that the control system remains stable even when the PH lifts a heavy or rigid object, because this makes the closed loop gain large and leads to the closed system unstable. According to the theory of stability analysis of nonlinear systems, we can only know the sufficient conditions that the system should be stable. Thus the nonlinear theory on stability is insufficient to be used to design the neuromuscular control system for improving its transient responses. This paper shows that the nonlinear system with a dead zone can be approximated to a linear feedback system and that well-known methods of analysis and design on linear control systems can be applicable. It is also shown through various simulation results that errors induced by approximation are practically negligible and thus the design methods are quite accurate.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.184-189
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• 2013

Compared to a multiphase SRM, a single-phase SRM has some advantages, such as lower number of switches and power converter size, which leads to gradually increasing in the household appliances and industrial applications. But the torque dead zone is existed in the single-phase SRM which decreases the starting capability of the motor and increases the torque ripple. In order to solve the aforementioned problems, a single-phase hybrid SRM with commercial ferrite permanent magnet is proposed in this paper. Basic design principle for the proposed structure is described. To verify the proposed structure, FEM is employed to get the characteristics of the proposed structure. Based on the analysis, a prototype is designed and manufactured. And, the experimental system is also constructed. The validity of the proposed structure is verified by the experimental results.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.347-353
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• 2012

Design and analysis of a novel 2-phase 4/5 Switched Reluctance Motor(SRM) is presented. The proposed motor employs a novel stator pole configuration. A novel SRM employs four-rotor and five-stator poles. The motor has no dead-zone and can be operate at any rotor position. The structure and operating principle are also described. The comparison between the proposed motor and a conventional two-phase 4/2 SRM is undertaken in this analysis. Furthermore, the Finite Element Analysis(FEA) and matlab-simulink are used to predict and simulate the performance of a proposed motor. The results of investigation indicate that the proposed structure offers a better performance in term of torque production.

• The Journal of Korea Robotics Society
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• v.8 no.3
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• pp.186-196
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• 2013

Since its introduction (e.g., [4, 6]), virtual coupling technique has been de facto way to connect a haptic device with a virtual proxy for haptic rendering and control. However, because of the single dependence on spring-damper feedback action, this virtual coupling suffers from the degraded transparency particularly during contact tasks when large device/proxy-forces are involved. In this paper, we propose a novel virtual coupling technique, which, by utilizing passive decomposition, reduces device-proxy position deviation even during the contact tasks while also scaling down (or up) the apparent inertia of the coordinated device-proxy. By doing so, we can significantly improve transparency between multiple degree of freedom (possibly nonlinear) haptic device and virtual proxy. In other to use passive decomposition, disturbance observer of [3] is adopted to estimate human force with some dead-zone modification to avoid "winding-up" force estimation in the presence of device torque saturation. Some preliminary experimental results are also given to illustrate efficacy of the proposed technique.