• Journal of Magnetics
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• v.19 no.4
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• pp.393-398
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• 2014

This paper proposes new types of models that have coaxial magnetic gear (CMG) configurations to increase torque transmission capability. They have flux concentrating structures at the outer low speed rotor, and permanent magnets (PMs) are embedded in the space between stationary pole pieces. The torque performances of the proposed models are compared with those of a basic CMG model. The harmonic torque components due to air gap field harmonics are also analyzed to investigate the torque contribution of each harmonic by using finite element analysis (FEA) and the Maxwell stress tensor. The proposed CMG model is optimized to have high torque density with low torque ripples by response surface methodology (RSM). Compared to the basic CMG model, the proposed model has a huge increase in transmitted torque density, and is very advantageous in term of PM use.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.9
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• pp.437-442
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• 2006

Cogging torque, the primary ripple component in the torque generated by permanent magnet (PM) motors, is due to the slotting on the stator or rotor. This article shows the reduction of cogging torque in a novel axial flux permanent magnet (AFPM) motor through the various design schemes. 3D finite element method is used for the exact magnetic field analysis. The effects of slot shapes and skewing of slot on the cogging torque and the average torque have been investigated in detail.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.3
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• pp.93-100
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• 2003

Switched reluctance motor(SRM) has some advantages such as low cost, high torque density but SRM has essentially high torque ripple due to its salient structure. In order to apply SRM to industrial field, torque ripple has to be reduced. This paper introduces optimal design process of SRM using an optimization algorithm of Progressive Quadratic Response Surface Modeling(PQRSM) and two-dimensional(2D) Finite Element Method(FEM). The electrical and geometrical design parameters have been adopted as 2D design variables. From this work, it can be obtained both the optimal design minimized torque ripple and the optima1 design maximized the average torque, respectively. Finally, this Paper Presents Performance comparison of two optimal designs and consider influence of the selected design variables in torque characteristics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2590-2597
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• 2002

A new torque measuring apparatus adopting the basic principle of a capacitive type sensor is proposed in this article. Two plate electrodes are working as a capacitive sensor, whose capacitance varies as torque is applied. One end of each plate is connected to the torque carrying shaft. Output characteristics of the torque sensor were theoretically analyzed and its validity was investigated through experiment. Calculations and calibration experiments show that the output is nonlinear, that is, the sensitivity is very high at low torque but decreases as torque increases. The sensitivity of the proposed system is about 100 times roughly higher than that of a conventional 4-strain gauge type torque sensor.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.279-284
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• 1999

Although the switched reluctance motor (SRM) has a several advantages such as simple magnetic structure, robustness, wide range of speed characteristics and simple driving, it has a considerable inherent torque ripple and speed variation duet to the driving characteristics of pulse current waveform and the nonlinear inductance profile. The high torque ripple and speed variation inhibits wide application. The minimization of the torque ripple is very important in high performance servo drive applications, which require smooth operation with minimum torque pulsations. This paper presents the new SRM torque modeling technique for the control of instantaneous torque. The SRM is modeled by the database of torque profiles for every small variation in currents and rotor angles, which is inferred from the several measured data by the adaptive neuro-fuzzy inference technique. Simulation results demonstrating the effectiveness of proposed torque modeling technique are presented.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.136-142
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• 2014

A major problem in Switched Reluctance Motor (SRM) is torque ripple, which causes undesirable acoustic noise and vibration. This work focuses on reducing the undesirable torque ripple in SRM by modifying stator and rotor geometry. This paper presents a comparative study on torque ripple minimization in SRM with modified pole shapes such as stator pole taper, stator pole face with non-uniform air gap and pole shoe attached to rotor pole. Further this paper presents a detailed sensitivity analysis of the effect of different geometrical parameters that alter the pole face shapes on the performance of SRM. The analysis is performed using finite-element method considering average torque and torque ripple as performance parameters. Based on the analysis, a design combining stator pole taper with non-uniform air gap is proposed to improve the torque characteristics of SRM. The dynamic characteristics of the proposed design are simulated and the results show satisfactory reduction in torque ripple.

• Journal of Power Electronics
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• v.18 no.3
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• pp.736-745
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• 2018

This paper presents an extended state observer (ESO) based direct torque control (DTC) for use in induction motor systems to handle the issues of time delays, load torque disturbances and parameter uncertainties. Direct torque control offers an excellent torque response and it does not require a proportion integration (PI) controller in the current loop. However, a PI controller is still adopted in the outer speed loop to generate the torque reference value, which is a slow method. An ESO based compound control scheme is proposed to improve the response rate and accuracy of the torque reference signal, especially when load torque is injected. In addition, the time delay problem is analyzed and compensated for in this paper to reduce torque ripples. The proposed disturbance compensation technique based direct control scheme is shown to have good performance both in the transient and stable states via simulations and experimental results.

• 유체기계공업학회:학술대회논문집
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• 1998.02a
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• pp.3-10
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• 1998

The situation frequently occurs in which the input torque capacity of the converter should be changed. It is known that the modification of the ou angles of the torque converter elements is suitable for such situation with diameter of flow path of the converter maintained. But so far it has been, predict correctly the converter characteristics as well as the effects of oulet torque capacity in the past numerical methods. In the present numeric introducing the interrow mixing planes, the torque capacity was satifactorily and it was shown that the torque capacity could be effectively changed by the oulet blade angles of pump and stator.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.242-247
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• 2007

Energy savings and environmental protection policies have been the general trend in the engine design. The friction power loss associated with the cam mechanism has become important. But it is difficult to measure the torque of rotating valvetrain in real engine environment because most of conventional torque meters are axial type. The objective of this paper is to develop new equipment which can be installed in a rotating camshaft. It uses strain gages to measure the elastic deformation of torque sensor which replaces the cam sprocket. It includes telemetry to transmit torque data via Bluetooth and induction power system to provide adequate power to rotating torque meter. The developed torque meter has good linearity and thermostability. It was installed in a real engine, and successfully measured the valvetrain torque.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.145-150
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• 2010

This paper deals with reduction of torque ripple in a brushless DC motor with input voltage control. The commutation torque ripple can be controlled with varying input voltage, but cogging torque is independent on it. So, in this paper a strategy for minimizing torque ripple is proposed by offsetting the cogging torque with deliberate voltage control. The optimal condition is determined with variable voltage levels and advance angles. As results, it is shown that the method causes 63% decrease of torque ripple.