Daebong Jung

Hybrid Thermostat Strategy for Enhancing Fuel Economy of Series Hybrid Intracity Bus

The recently developed power distribution strategies in hybrid electric vehicles (HEVs) are often hard to apply, or the mathematical backgrounds are burdened by very complicated calculations. In this paper, a new control strategy, referred to as a hybrid thermostat strategy, is proposed for a series-type HEV (SHEV). The proposed strategy has its foundation in the thermostat strategy and incorporates merits from the power follower strategy such that it overcomes those strategy weaknesses and accomplishes increased efficiency with a practical concept. The development of the proposed strategy is based on AMESim and Simulink cosimulation with Simplex method optimization.

Study on Optimization of Generation System in Series HEV Bus

최근 화석 연료 고갈 문제와 배기 가스에 의한 환경 오염 문제가 대두됨에 따라 이에 대응하기 위한 대안으로 하이브리드 전기 자동차(HEV)가 주목 받고 있다. HEV는 엔진과 모터를 동시에 이용하는 자동차로써 연비 향상과 배기 가스 저감을 동시에 달성할 수 있다. 특히 일정 구간을 반복 운행하는 버스의 경우 일반 승용차에 비하여 일정한 주행 패턴을 보이므로 하이브리드화를 통하여 더 높은 연비 향상과 배기 가스 저감을 이룰 수 있다. HEV 중에서도 엔진을 전기를 발전시키는 용도로만 사용하고 차량 구동은 모터만을 이용하는 직렬형 HEV 는 엔진을 최적의 효율을 보이는 작동 영역에서 동작 시킬 수 있다는 장점이 있다. 이런 장점에도 불구하고 현재 직렬형 HEV 는 병렬형 또는 동력 분기형 HEV에 비하여 연구가 미비한 실정이다. 직렬형 HEV 의 경우 엔진을 이용하여 기계적 에너지를 전기 에너지로 변환한 후, 다시 이를 기계적 에너지로 변환하여 Key Words : Series HEV Bus(직렬형 하이브리드 전기 버스), Engine(엔진), Generator(발전기), Fuel Economy(연비), Optimization(최적화) 초록: 차량의 연비를 향상시키고 배기가스를 저감하기 위하여 하이브리드 자동차에 대한 많은 연구가 진행되고 있다. 하지만 이런 연구들은 병렬형이나 동력분기식 하이브리드 자동차에 집중되어 있다. 상대적으로 직렬형 하이브리드 자동차에 대한 연구는 부족한 실정이다. 직렬형 하이브리드 자동차의 경우 엔진이 차축과 분리되어 있으므로 엔진을 최적의 효율 지점에서 작동 시킬 수 있는 장점이 있다. 이런 장점을 최대한으로 이용하기 위하여 발전 시스템을 최적화 하는 연구가 필수적이다. 따라서 본 연구에서는 엔진을 Optimal Operating Line 상에서 작동시키면서 발전기 또한 최적 효율 지점에서 사용할 수 있는 최적화 방법을 제안하였다. 또한 기존의 발전시스템을 갖는 직렬형 하이브리드 버스와 최적화 된 발전 시스템을 갖는 직렬형 하이브리드 버스의 연비를 시뮬레이션을 이용하여 비교, 연비 향상도를 평가하였다. Abstract: In order to improve fuel economy and emissions, many studies of HEV have been conducted. However, most of these studies concentrate on parallel or power-split HEVs. Series-type HEVs have some advantages over parallel and power-split HEVs. One is that the engine is operated at high efficiency since the engine and the driveshaft are decoupled. Nevertheless, the optimization of the powertrain system of series HEV has not been specifically addressed. We conduct an optimization of the generation system of a series HEV based on the series HEV bus. The main objectives are to simulate the system and to compare the fuel economies of conventional and optimized generation systems.

Series-Type Hybrid Electric Bus Fuel Economy Increase with Optimal Component Sizing and Real-Time Control Strategy

Key Words: Series Hybrid Electric Vehicle(직렬형 하이브리드 자동차), Optimization(최적화), Dynamic Programming(동적계획법), HILS(하드웨어 인 더 루프 시뮬레이션) 초록: 직렬형 하이브리드 자동차는 구조가 간단하고 단품들의 효율이 높기 때문에 연비성능이 우수하며, 병렬형과 비교하여 배터리, 엔진, 모터의 용량이 상대적으로 고용량인 특징을 가진다. 본 연구에서는 직렬형 하이브리드 자동차의 최적용량매칭을 통해 최적의 연비를 도출하고, 실시간 시뮬레이션 환경에서 사용될 알고리즘을 개발한다. 연구에서 진행된 용량매칭은 모터, 엔진/발전기 및 배터리를 대상으로 13개 주행 사이클에 대하여 순차적으로 이루어 졌으며, 이를 위해 Matlab 환경에서 최적화 기법인 DP(Dynamic Programming)을 사용하였다. 실시간 성능검증을 위한 차량모델은 Simulink 및AMEsim을 기반으로 개발되었고 실시간 제어로직이 구현된RCP(Rapid Control Proto-typing)와 연동하여 그 성능을 확인할 수 있었다. Abstract: The interest in reducing the emissions and increasing the fuel economy of ICE vehicles has prompted research on hybrid vehicles, which come in the series, parallel, and power-split types. This study focuses on the series-type hybrid electric vehicle, which has a simple structure. Because each component of a series hybrid vehicle is larger than the corresponding component of the parallel type, the sizing of the vehicle is very important. This is because the performance may be greater or less than what is required. Thus, in this research, the optimal fuel economy was determined and simulated in a real-world system. The optimal sizing was achieved based on the motor, engine/generator, and battery for 13 cycles, where DP was used. The model was developed using ASCET or a Simulink-Amisim Co-simulation platform on the rapid controller prototype, ES-1000.

Study of Energy Management Strategy Considering Various Working Modes of Plug-in Hybrid Electric Tractor

In recent years, eco-friendliness and high fuel economy have become important issues for commercial tractors. Electric tractors are often required for operation in a greenhouse. However, the battery capacity limits the available operation time. To overcome this problem, a plug-in hybrid electric tractor is considered a reasonable alternative. This tractor has a basic driving ability and can operate in various working modes such as mower, rotary, loader, and trailing. This study focuses on the energy management strategy by considering various working modes.

Study on the Development of Control Strategy for Series Hybrid Electric Bus based on HILS

In recent days, the study on hybridization of the heavy-duty is going on, actively. Especially, the improvement of fuel economy can be maximized in the intra-city bus because it drives the fixed route. For developing the hybrid electric intra-city bus, optimized control strategy which is possible to be applied with real vehicle is necessary. If the real-time control strategy is developed based on the HILS, it is possible to verify the real-time ability and fail-safety function which has the vehicle stay in safe state when the functional errors are occurred. In this study, the HILS system of series hybrid electric intra-city bus is developed to verify the real time control strategy and the fail-safety functions. The main objective of the paper is to build the HILS system for verifying the control strategy (rule-based control) which is implemented to reflect the Dynamic Programming results and fail-safety functions.

Comparison of Control Strategies for Military Series-Type HEVs in Terms of Fuel Economy Based on Vehicle Simulation

Military vehicles, compared to conventional vehicles, require higher driving performance, quieter operation, and longer driving distances with minimal fuel supplies. The series hybrid electric vehicle can be driven with no noise and has high initial startup performance, because it uses only a traction motor that has a high startup torque to drive the vehicle. Moreover, the fuel economy can be improved if the vehicle is hybridized. In series hybrid electric vehicles, the electric generation system, which consists of an engine and a generator, supplies electric energy to a battery or traction motor depending on the vehicle driving state and battery state of charge (SOC). The control strategy determines the operation of the generation system. Thus, the fuel economy of the series hybrid electric vehicle relies on the control strategy. In this study, thermostat, power-follower, and combined strategies were compared, and a 37% improvement in the fuel economy was implemented using the combined control strategy suggested in this study.

Optimal torque distribution strategy for dual traction motors in a series hybrid electric intra-city bus

In hybrid vehicles, the focus in optimisation methodologies to improve the fuel economy has generally been on the energy flows between the engine motor and battery, but the energy distributions in the traction motor unit have received little attention. Thus, the energy flow from the engine/generator unit to the traction motors that is determined by optimal control strategies may not be transferred to the wheels in the most efficient manner. To address such problems, this research studies an optimal torque distribution for the traction motors where an optimal torque distribution map is used that contains information for the most efficient distribution at all operating points. The optimal power distribution, apart from the energy flow from the engine to the traction motor unit, could be achieved for all operating regions with realistic bus speed profiles. As a result, the favourable type for the proposed strategy could be defined. The proposed strategy was demonstrated through simulations using AMEsim and Simulink co-simulation.