Modeling and control strategy of diesel hybrid electric vehicle using manual transmission

Abstract

Manual transmission based diesel engine system have been mainly applied to commercial vehicle such as a truck, which have outstanding fuel economy, power transfer efficiency and lower cost compared to vehicle using automatic transmission. However, annual tightening of fuel economy and emissions regulations has required dramatic fuel economy and emissions performance improvements. And prior studies proposed energy management strategies considered only fuel consumption and exhaust emissions from the engine without considering the transient effects and shift characteristics of manual transmission. As a result, the exhaust emission reduction considering the transient emission characteristics for dynamic engine load change was not properly evaluated, thus, causing errors in the exhaust emission reduction evaluation and the energy management strategy of the actual vehicle. Furthermore, in the case of diesel trucks, which employ manual transmissions, a control strategy considering driver’s gear shift characteristics is required. Yet, to the best of the author’s knowledge, none of the prior studies considered this feature in their developed control strategies. This paper proposes a powertrain model that considers transient emission characteristics due to frequent engine on/off and dynamic engine load changes and driver’s gear shift characteristics of parallel hybrid diesel-electric vehicles using manual transmissions. Based on the powertrain model, we developed an optimal control strategy that considers driver’s gear shift characteristics and transient emission reduction and fuel economy using an optimization technique such as dynamic programming. A systematic methodology to derive powertrain energy management strategies for diesel-electric vehicles was developed. Mode selections and power split ratio calculations were considered, and a control strategy considering the driver’s gear shift characteristics and transient PM emission of diesel engine is extracted from the optimal control results obtained using dynamic programming, which is then applied to powertrain control algorithm of diesel hybrid electric vehicle.