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신창우(Chang Woo Shin),정종렬(Jong Ryeol Jeong),임원식(Won Sik Lim),차석원(Suk Won Cha) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
There is a big difference between electric vehicles(EVs) and conventional vehicles in the construction and power flow of the powertrain. Therefore, whenever someone develops an EV, they should take into consideration improvement of dynamic performance in EVs. In this paper, we conducted a research on a design method to determine the traction motor characteristics and the final reduction gear ratio in the electric bus, which consists of a motor, a battery system and a final reduction gear. We analyzed the required motor power of the electric bus based upon the maximum vehicle speed needed and the grading performance of the vehicle. This paper proposed a design method for the optimal final reduction gear ratio to satisfy vehicle acceleration performance by using a motor efficiency according to the driving cycles. By using the determined motor performance and the optimal gear ratio, backward simulation was conducted to confirm a variation of SOC(state of charge) for city bus driving cycles.
신창우(Changwoo Shin),정종렬(Jongryeol Jeong),임원식(Wonsik Lim),차석원(Sukwon Cha),이춘범(Chunbeom Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
It is possible to estimate regenerative braking energy on an electric bus with a fixed driving cycle. However, in low vehicle speed ranges, it is difficult to regenerate, because of the low motor electromotive force generated at low motor rotational speeds. Thus the most important thing of electric vehicles is their ability to recover amounts of braking energy with considering vehicle safety. This paper shows amounts of traction and braking energy of bus driving cycles, which are composed of Seoul city bus cycles. A regenerative braking control algorithm is proposed considering low vehicle speed ranges and braking force distribution on front and rear wheel. A forward simulation program is developed to investigate fuel efficiency by limit speed of the regenerative braking algorithm. Based on the simulation results by limit speed, fuel efficiency for an electric bus is compared according to the bus driving cycles. Results of the comparison suggest an appropriate driving cycle for the target vehicle.
락업클러치 작동에 따른 구동계의 이상 진동에 관한 연구
신창우(Changwoo Shin),이대흥(Daeheung Lee),임원식(Wonsik Lim),차석원(Sukwon Cha),김진현(Jinhyun Kim),강상욱(Sangwook Kang) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
Lock-up clutch system has been widely adapted to the present automatic transmission vehicles for reducing fuel consumption and improving efficiency of vehicle drivetrain system. However, the abnormal vibrations such as slip shudder and surge might be happened by the lock-up clutch operation at the low speed. In this paper, we focused on the abnormal vibrations in the unstable regions of the engine performance curve. Based on the dynamic equations of vehicle system, we designed simulation program which includes engine, torque converter, lock-up clutch, transmission and vehicle. To analysis the abnormal vibrations in drivetrain, we carried out simulations for several driving conditions according to unstable regions of engine performance curve. As a result of simulation, the abnormal vibrations in drivetrain are severely occurred in unstable regions of an engine. Thus, lock-up clutch operation would be better to avoid in this region.
AT 차량의 댐퍼클러치 작동에 의한 연비와 이상진동 분석
신창우(Changwoo Shin),김범수(Beomsoo Kim),임원식(Wonsik Lim),차석원(Sukwon Cha) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
Automatic transmission vehicles have steadily increasing due to convenience and comfort for drivers. A damper clutch in automatic transmission system has some advantages of fuel economy and dynamic performance. In this paper, dynamic modeling was performed to confirm the effects of damper clutch operation. Using simulation program, fuel economy on a system with a lock-up control was compared with that on a system with a slip control on a test cycle. The result of simulation also depicted abnormal vibration during damper operation at low throttle condition. To analyze the abnormal vibrations in the drivetrain, simulations for several driving conditions was conducted. Two sides by a damper clutch operation were confirmed.
전기 버스의 감속비 최적화를 위한 주행 성능 시뮬레이션 분석
신창우(Changwoo Shin),정종렬(Jongryeol Jeong),임원식(Wonsik Lim),차석원(Sukwon Cha),이춘범(Chunbeom Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
There have been efforts to enhance the efficiency of electric vehicle Electric vehicles. One of these is the optimal reduction gear ratio, because operating points of traction motor are revised according to a reduction gear ratio. This paper proposed a design method for the optimal reduction gear ratio of an electric bus using a motor efficiency according to bus test driving cycles. For optimal gear ratio, analysis for test driving cycles was performed. To investigate the effect of the optimal gear ratio, backward simulation was conducted to confirm a variation of SOC(state of charge) for bus test driving cycle according to various reduction gear ratio. Simulation result using the optimal gear ratio was compared with those of other cases.
자유 음장 조건에서 개선된 빔형성 방법을 이용한 흡음재의 수직 입사 표면 임피던스 측정
신창우(Shin, Chang-Woo),선종천(Sun, Jong-Choen),강연준(Kang, Yeon-June),백순권(Paik, Soon-Kwon) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.6
An improved beamforming method is proposed to measure the surface impedance of absorbing materials in a free field. It is possible to estimate the surface impedance by decomposing measured signals into incident and reflected signals by using the spatial filter matrix of the beamforming method. Wavelet do-noising techniques which reduce the white Gaussian noise are applied to improve the results. Phase calibration method is also used to improve the results of the measured surface impedance in a low frequency range. The results of the normal incidence experiments that are performed in a semi-anechoic chamber are verified by comparing with those of the standard test method that is presented in ASTM E1050. The proposed method is found to be reliable to measure the surface impedance for frequencies higher than 400 Hz.
신창우(Chang Woo Shin),김형균(Hyungkyoon Kim),김문겸(Mun Kyum Kim),임원식(Wonsik Lim),차석원(Sukwon Cha) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
A drivability of vehicles means subjective perception for dynamic performance and comfort of a vehicle in response to driver input. Subjective evaluations by experienced test driver have been primarily used to assess the drivability in automotive companies. These evaluations are limited in repeatability and require much time and cost. In this paper, vehicle test was conducted to measure data for objective drivability evaluations in heavy duty vehicles. The evaluation indices for drivability were selected from references, which are related to ride comfort and objective evaluation of drivability, according to operation conditions. The quantitative evaluation method was proposed by using weighting factors obtained from the regression analysis of subjective evaluations. Based on the proposed method, drivability for heavy duty vehicles was evaluated quantitatively under various operation conditions. The results of this evaluation were similar to those of subjective evaluation.