• 농업과학연구
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• 제46권4호
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• pp.723-735
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• 2019

The power-train is the most important component of an agricultural tractor. In this study, the strength of the driving gear transmission of an 82 kW-class tractor was analyzed using equivalent torque during plow tillage. The load measurement system consisted of an engine revolution speed sensor, torque-meters, revolution speed sensors for four axles, and pressure sensors for two hydraulic pumps. The load data were measured during plow tillage for four speed stages: F2 (2.78 km/h), F5 (5.35 km/h), F7 (7.98 km/h), and F8 (9.75 km/h). Aspects of the gear-strength such as bending stress, contact stress, and safety factors were analyzed under two torque conditions: the equivalent torque at the highest plow load for the F8 speed stage and the maximum engine torque. The simulation results using KISSsoft showed that the maximum engine torque conditions had a lower safety factor than did the highest equivalent torque condition. The bending safety factors were > 1 at all gear stages, indicating that gear breakage did not occur under actual measured operating conditions, nor under the maximum torque conditions. However, the equivalent torque condition in the contact stress safety factor was > 1, and the maximum torque condition was < 1 at the first gear pair. The method of analysis using the equivalent torque showed lower stress and higher safety factor than did the method using maximum torque. Therefore, when designing a tractor by applying actual working torque, equivalent torque method would support more reliable product development.

• 전기의세계
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• 제26권4호
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• pp.41-53
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• 1977

With the equivalent series circuit analyzed aby revolving field theory and drawn by using the equivalent circuit constant ratios in capacitor motor with windings not in quadrature having space harmonics in its magnetic field (the above ratios are the equivalent circuit constants for the fundamental flux to the magnetizing reactance of the circuit), the equation for the alternating torque with twice line freequency in the motor is directly derived, and the alternating torque is measured with the self-made stator vibration angle amplitude measuring apparatus that is composed of a pickup, filter, photoelectric pickoff etc. The measured values satisfactorily compared with computed values. The properties of the alternating torque characteristics for respective harmonic fluxes and the r5esultant alternating torque characteristic, the effects of the alternating torque characteristics for respective harmonic fluxes on the resultant alternating torque characteristic, the effects of the variation in the motor constants and the equivalent circuit constant ratios for the fundamental flux on the alternating torque characteristics for respective harmonic fluxes and the resultant alternating torque characteristic, are made clear, applying the equation. There exist the optimum values of the motor constants and the equivalent circuit constant ratios for the fundamental flux for decreasing the alternating torque, and the value could be determined in design by the method presented in this paper.

• 조명전기설비학회논문지
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• 제28권1호
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• pp.45-49
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• 2014

Torque of an induction motor is generally calculated by simplified equivalent circuit. However, the torque has an error since it is calculated by simplified equivalent circuit. In this paper, stator and rotor currents, torque, efficiency, and power factor are derived from the equivalent circuit of an induction motor using mesh analysis method. Then, they are compared with those calculated from simplified equivalent circuit.

• 한국정보전자통신기술학회논문지
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• 제12권4호
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• pp.359-365
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• 2019

본 연구는 트랙터 변속기의 성능평가, 내구성 향상 및 최적 설계 등을 위한 기초 연구로써 로타리 작업에 따른 78 kW급 농업용 트랙터의 엔진 토크를 CAN 통신을 이용하여 수집하고, 등가 토크를 분석하였다. 신뢰성 높은 트랙터 개발을 위해서는 실제 농작업 환경에서 발생하는 부하를 등가 토크로 변환하여, 분석하는 것이 필요하다. 등가 토크는 대표적인 누적 손상법인 Palmgren-Miner 식으로 작업 및 선회구간에 대하여 계산되었으며, 각각 229.2, 136.7 Nm로 나타났다. 로타리 작업구간에서 최대 및 평균 토크는 각각 336.0, 234.4 Nm로 나타났으며, 선회구간의 최대 및 평균 토크는 288.0, 134.6 Nm로 나타났다. 로타리 작업구간에서의 엔진 토크는 PTO를 통해 토양을 경운하기 때문에 선회구간보다 높게 나타났다. 엔진의 최대 및 정격 토크는 각각 387.0, 323.0 Nm로, 로타리 작업 및 선회구간의 등가 토크보다 각각 183%, 136% 높게 나타났다. 국내 트랙터 회사는 일반적으로 엔진의 정격 토크를 기준으로 변속기를 설계하기 때문에, 실제 작업 토크와 다소 차이가 있다. 그러므로 최적 설계를 위해 실제 작업 토크를 고려하는 것이 필요할 것으로 판단된다.

• Journal of Magnetics
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• 제21권4호
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• pp.570-576
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• 2016

The shape optimization of the stator and the rotor is important for electrical motor design. Among many motor design parameters, the stator tooth and yoke width are a few of the determinants of noload back-EMF and load torque. In this study, we proposed an equivalent magnetic circuit of motor stator for efficient stator tooth and yoke width shape optimization. Using the proposed equivalent magnetic circuit, we found the optimal tooth and yoke width for minimal magnetic resistance. To verify if load torque is truly maximized for the optimal tooth and yoke width indicated by the proposed method, we performed finite element analysis (FEA) to calculate load torque for different tooth and yoke widths. From the study, we confirmed reliability and usability of the proposed equivalent magnetic circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.983-984
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• 2011

An effective estimation method of equivalent circuit parameters of three-phase induction motor by using FEM is presented in this paper. Arbitrary three torque-speed points at asynchronous speed on the torque-speed curve are required by using time-stepping FEM, then the equivalent circuit parameters of IM can be calculated rapidly with presented method. After obtaining the equivalent circuit parameters, the general analysis method based on equivalent circuit can be used to get entire torque-speed curve very quickly. Although the purely numerical method such as FEM also can estimate torque-speed curve directly and accurately, however, usually this process is time consuming.

• 대한기계학회논문집A
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• 제21권3호
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• pp.369-377
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• 1997

The torque converter, a major part of automatic transmissions, has many difficulties in analysis due to the factors such as power transmission through fluid flow, complex internal geometry, and various operating conditions. Because of such difficulties, the dynamic analysis and design of a torque converter are generally carried out by using equivalent performance model which is based on the concept of mean flow path. Since the design procedures of a torque converter are essential technology of automotive industry, the details of the procedures are rarely published. In this study, the basic design procedures of a torque converter are systemized and coded based on the equivalent performance model. The mathematical methods to deal with mean flow path determination and the core-shape are developed. And by using this model, the method of determination of performance parameters satisfying the requested performance is proposed. Finally, to embody the three-dimensional shape, the intermediate blade angles which maximize the tractive performance are determined and laid out.

• 조명전기설비학회논문지
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• 제27권1호
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• pp.109-112
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• 2013

It is well known that the maximum torque of a 3-phase induction motor does not vary as the resistance of rotor varies by proportional shifting. However, proportional shifting is derived using simplified equivalent circuit of induction motor. Therefore, there are some errors in the torque characteristics shown in the text book. This paper presents the torque characteristics using not simplified equivalent circuit but equivalent circuit. Errors produced by simplified equivalent circuit are presented.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.327-331
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• 2006

This paper presents the analysis method for the torque characteristic of the 1-phase induction motor considering space harmonics in the air gap. The equivalent circuit method is used, where the circuit constants are obtained by classic theory. In addition, the space harmonic components in air gap magneto motive force are analyzed and added to the equivalent circuit to obtain accurate torque characteristics in low speed regions. Each torque component due to the harmonics is calculated and the total torque characteristic is obtained and compared with the measurement result.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권11호
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• pp.597-603
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• 1999

Due to its simple construction, operation steadiness and low cost, claw pole step motor is widely used for OA machine and automobile. This paper deals with analysis fo claw pole motor, especially eyeing to dynamic characteristics. To analyze dynamic characteristics of claw pole step motor, torque development in each angular step of rotor are surveyed and torque equation is drived using permeance method. To adopt the airgap MMF, the magnetic equivalent circuit of the motor is introduced. On the base of the magnetic equivalent circuit, the air gap flux equation is derived. To get a optimum design of the motor, the torque characteristic is studied in variation of coil data and remanence value of permanent magnetic material.