Development of a Generalized Model to Predict Efficiency of Electrified Power Transmission Considering Optimal Driving Efficiency
2022-01-0776
03/29/2022
- Event
- Content
- The expansion of electrified powertrain over the past decade due to strict fuel efficiency regulations has led to the development of various powertrain systems. While operating the engine at high efficiency using a multi-speed gearbox is a feature of existing powertrain system development, recent trends are being developed to improve system operation efficiency based on a multi-power source configured by mixing an engine and a motor in a simple gearbox. This situation makes it necessary to analyze the overall system efficiency to compare the competitiveness of each system from the early stages of powertrain system development. The prediction of powertrain system efficiency is a process to understand how the system is composed and what strategy can be used for the system in driving cycle. The driving efficiency in a vehicle is determined not only by the efficiency of each power source, but also by loss on the path through which the power flows and how to use each power source to drive efficiently. In this study, a generalized numerical model is developed to calculate the loss of gearboxes with various power sources and various power flow paths. This numerical model is newly applied with a generalized equation for power flow by various gear pair, including the loss equations of previously developed and verified gearbox parts such as gear, bearing, clutch and so on. In addition, the optimal operating efficiency in the fuel consumption test cycle was calculated in consideration of the system efficiency covering the total vehicle load, power source efficiency, and gearbox transfer efficiency. The developed model is employed to predict the efficiency of several systems. In the early stages of system development, the efficiency comparison at optimal operating points for fuel economy modes such as WLTP and FTP shows that it can be a more objective and powerful system development method.
- Citation
- KIM, D., WON, K., Son, W., and Park, K., "Development of a Generalized Model to Predict Efficiency of Electrified Power Transmission Considering Optimal Driving Efficiency," SAE Technical Paper 2022-01-0776, 2022, .