• Advances in Computational Design
• /
• 제8권3호
• /
• pp.237-253
• /
• 2023

Torque ripple content and variable switching frequency operation of conventional direct torque control (DTC) are reduced by the integration of space vector modulation (SVM) into DTC. Integration of space vector modulation to conventional direct torque control known as SVM-DTC. It had been more frequently used method in renewable energy and machine drive systems. In this paper, SVM-DTC is used to control the rotor side converter (RSC) of a wind driven doubly-fed induction generator (DFIG) because of its advantages such as reduction of torque ripples and constant switching frequency operation. However, flux and torque ripples are still dominant due to distorted current waveforms at different operations of the wind turbine. Therefore, to smoothen the torque profile a Neural Network Controller (NNC) based SVM-DTC has been proposed by replacing the PI controller in the speed control loop of the wind turbine controller. Also, stability analysis and simulation study of DFIG using process reaction curve method (RRCM) are presented. Validation of simulation study in MATLAB/SIMULINK environment of proposed wind driven DFIG system has been performed by laboratory developed prototype model. The proposed NNC based SVM-DTC yields superior torque response and ripple reduction compared to other methods.

• 대한기계학회논문집A
• /
• 제26권6호
• /
• pp.1085-1091
• /
• 2002

General vehicle is evaluated by its acceleration, fuel economy, NVH (Noise, Vibration and Harshness) and subjective (such as launching feel) performance. The first step to enhance its performance is to know how much each component affects on the vehicle performance. It is very important to know what is the key factor of the component among many specifications. Hydraulic torque converter can be expressed by means of its performance curve (torque ratio and capacity factor). In this paper, the key factor of torque converter, which affect vehicle performance, are explored by using Taguchi method. Moreover, general sensitivity analysis method is compared with Taguchi's experiment.

• 한국자동차공학회논문집
• /
• 제6권6호
• /
• pp.15-23
• /
• 1998

A three dimensional simulation of the fluid flow in an automotive torque converter was conducted adopting the mixing plane model implemented in the computational fluid dynamics program CFD-ACE. The present numerical results for performance characteristics showed a good agreement with the experimental results. In the flow of the torque converter, recirculating flow regimes were found mostly at the suction side of each element, which caused the performance decrease. The recirculating flow can be minimized by the optimization of the blade geometries.

• 한국자동차공학회논문집
• /
• 제13권2호
• /
• pp.37-43
• /
• 2005

A haptic steering system which reflects steering reaction torque has been developed for a fixed base vehicle simulator. The haptic steering system consists of a steering effort sensor, MR-clutch, AC servo motor and controller. In order to generate realistic steering torque feel to driver and at the same time to meet real-time simulation requirement, 3D torque map is constructed by experimental data and torque generation algorithm using the torque map has been also developed. 3D torque map is constructed using curve fitting and interpolation of the measured values of the steering angle, velocity and steering torque from actual slalom test on the proving ground. In order to carry out performance test of the developed haptic steering system, a fixed based vehicle simulator is constructed by integrating real time vehicle dynamics module, VR-video/audio module, and the haptic steering system. Steering torque and steering angle curves have been obtained from virtual testing in the vehicle simulator and performance of the haptic steering system has been evaluated.

• Journal of Mechanical Science and Technology
• /
• 제19권3호
• /
• pp.792-801
• /
• 2005

This paper discusses a dc motor equipped electric power steering (EPS) system and demonstrates its advantages over a typical hydraulic power steering (HPS) system. The tire-road interaction torque at the steering tires is calculated using the 2 d.o.f. bicycle model, in other words by using a single-track model, which was verified with the J-turn test of a real vehicle. Because the detail parameters of a steering system are not easily acquired, a simple system is modeled here. In previous EPS systems, the assisting torque for the measured driving torque is developed as a boost curve similar to that of the HPS system. To improve steering stiffness and return-ability of the steering system, a third-order polynomial as a torque map is introduced and modified within the preferred driving torques researched by Bertollini. Using the torque map modification sufficiently improves the EPS system.

• Journal of Advanced Marine Engineering and Technology
• /
• 제6권1호
• /
• pp.25-33
• /
• 1982

The characteristics of the stator current and torque of a small three- phase squirrel cage induction motor and studied experimentally under the situation of a single-phase operation due to various causes. Through the experiments, the torque-slip and current-slip curve of single-phase circuit as well as three-phase circuit are obtained and the needed constants are determined. The stator current and torque are calculated by the current and torque equations derived by the unbalanced circuit theory. The numerical values obtained from the above methods are compared with the experimental values under the same conditions. The results of the study are summerized as follow; 1) The values computed by the unbalanced circuit theory generally come to approach the values recorded through experiments. 2) Near the rated load, speed drop is less than 1.2 per cent of the speed of three-phase induction motor and torque reduces less than 3 per cent of it of three-phase induction motor when three-phase induction motor is run under a single-phase. On the other hand, the stator current in a single-phase circuit is more than 1.9 times of it in three-phase circuit. 3) The stalling torque in a single-phase circuit is reduced to about 41 per cent of it in three-phase circuit while the corresponding slip is moved toward the synchroneous speed and the corresponding stator current is increased.

• 대한기계학회논문집A
• /
• 제22권2호
• /
• pp.428-436
• /
• 1998

A TCS slip control system improves acceleration capability and steerability on slippery roads through engine torgue and/or brake torque control. This research mainly deals with the engine control algorithm via the adjustment of the engine throttle angle. The following new control strategy is proposed and investigated ; the TCS slip controller whose input is the difference between the desired driving wheel speed corresponding to the optimum slip ratio and the actual speed yields the target engine torque and then estimates the throttle angle based on the engine performance curve. Various simulation and hardware-in-the-loop simulation have been carried out. The results show the proposed strategy may compensate for the inherent nonlinearity between variation of the throttle angle and variation of the engine torque and produce better performance than the previous strategies without the engine map, especially in the high speed region.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제2권1호
• /
• pp.45-50
• /
• 2013

This paper presents design of induction motor in very low temperature for LNG main cargo pump and comparison of two motors. One is the motor for using in room temperature and another is the motor for using very low temperature. This paper designs with Equivalent circuit Method and uses Finite Element Method to analysis. The motor for very low temperature considers variation of coil resistivity due to temperature change and compare torque characteristic with the motor for room temperature. Design element of motor for very low temperature considers resistivity variation following temperature change on going through this paper. The result shows that two types of motors are almost same torque curve characteristic even though they are not the same environment.

• 한국방재학회 논문집
• /
• 제8권2호
• /
• pp.97-103
• /
• 2008

Determination of stress-strain relationship in torsional tests is complicated due to nonuniform stress-strain variation occurring linearly with the radius in a soil specimen in torsion. The equivalent radius approach is adequate when calculating strain at low to intermediate strains, however, the approach is less accurate when performing the test at higher strain levels. The modified equivalent radius approach was developed to account for the problem more precisely. This approach was extended to generate the plots of equivalent radius ratio versus strain using modified hyperbolic and Ramberg-Osgood models. Results showed the effects of soil nonlinearity on the equivalent radius ratio curves were observed. Curve fitting was also performed to find the stress-strain relationship by fitting the theoretical torque-rotation relationship to measured torque-rotation relationship.

• 전기학회논문지
• /
• 제67권1호
• /
• pp.52-60
• /
• 2018

The winding of the motor stator coil is broken due to external stress and various factors. If the proper current is not injected when interturn fault(ITF) occurs, the fault can easily be expanded and the motor can be finally destroyed, resulting in many problems with time costs and safety. In this paper, the power loss limit concept, which is the inherent durability of each motor, is applied to secure safety by controlling the total power loss of the motor within the limits. So, we propose an algorithm that can control maximum torque per minimum power loss based on constant torque curve and power loss limit. To verify the proposed method, the simulation and experimental results with an Interior permanent magnet synchronous motor(IPMSM) having an ITF are shown.