Analysis of PnG strategy focusing on the effect of the duration of pulse mode

Abstract

When using Pulse and Glide (PnG) strategy, the vehicle accelerates and decelerates repeatedly. With the considered vehicle, during pulse mode the engine outputs positive power to drive the vehicle; during glide mode the engine idles and is decoupled from the drivetrain. PnG strategy was found to be more fuel-economic than constant speed (CS) strategy in a car-following scenario. In our past research, it was found that the most fuel-economic operating point of the engine during pulse mode is not the minimum BSFC point, but an operating point outputting a lower power. In this study, the effects of the duration of pulse mode on the following three factors are investigated: fuel economy, frequency of the speed pattern, fluctuation amplitude of vehicle speed. Optimization problems are solved to find the most fuel-economic manner of PnG strategies for specified values of the duration of pulse mode in a free-driving scenario. The calculation results for two types of engines with different fuel consumption characteristics are compared to validate the conclusion. It is found that the frequency of the speed pattern decreases monotonically as the duration of pulse mode increases. However, PnG strategy remains to be more fuel-economic than CS strategy when the frequency of the speed pattern of PnG strategy changes within a wide range. This conclusion holds for both engine characteristics. Therefore, it is considered that PnG strategy is worth to be implemented for fuel economy. The results can be used to trade off the fuel economy and the ride comfort by setting the value of the duration of pulse mode appropriately considering the frequency of the speed pattern and the fluctuation amplitude of the vehicle speed.