Research On The Emission And Energy Consumption Evalution Methods Of Heavy Duty Hybrid Electric Vehicles

Energy crisis and environmental pollution urge people to study and develop the new energy vehicles. Because of its higher fuel economy and emission reduction effect, HD-HEV has become the research and development hot spots of many automobile manufacturers. As the improvement of technology, HEVs have entered the commercialization and market stages. But in order to promote the technical maturity and market penetration of HD-HEV, We must establish the intact evaluation system.In this paper, the test methods and relevant standards of emission and energy consumption of HD-HEV were investigated. And two test methods were studied deeply, separately the method based on heavy-duty chassis dynamometer and full-Flow dilution sampling system, the on-road test based on PEMS.The test system of heavy-duty chassis dynamometer and FFDSS was integrated. The emission and energy consumption of a parallel hybrid vehicle were tested by the test system. The test results showed that, the heavy-duty chassis dynamometer could simulate the on-road driving resistance of test vehicle under the error of less than 2.5%, the braking energy recovery process of test vehicle could also be reproduced. Repeatability of test results showed that, in addition to HC and PM emissions, the relative error of emission factor of CO was less than 7%, the relative errors of emission factor of CO2 and NOx, fuel consumption per hundred kilometers, test mileage each test was less than 5%, test results have better repeatability. Test results of emission and energy consumption under cold and hot test conditions showed that, under cold test condition, fuel consumption, emission factors of THC, CO, CO2 and PM were separately 1.1 times,2.34 times,1.25 times,1.1 times and 1.7 times than those under hot test condition. The THC emission increased significantly, but the NOx emission had little change.The on-road test system based on PEMS was integrated. So the emission and energy consumption of a series-parallel hybrid vehicle were tested by the test system. And the emission and energy consumption of test vehicle were also tested on heavy-duty chassis dynamometer based on PEMS. The test results showed that, through on board driving cycle testing system (OBDCTS), the driver could reproduce the test cycle with high accuracy, the correlation coefficient between actual speed and target speed was around 0.98, the slope of the fitted line was greater than 0.97. Repeatability of test results showed that, in addition to HC and PM emissions, the repeatability of several other measurement parameters could guarantee less than 10%, which could meet the test accuracy. Test results show that, the on-road test method based on PEMS is feasible.The comparative results between two test methods show that, the driver could reproduce the test cycles with high accuracy, but under the test method based on heavy-duty chassis dynamometer, the driver could reproduce the test cycles better. From repeatability of test results, the repeatability of heavy-duty chassis dynamometer test method was better than those under on-road test method. From the view of the relevance and consistency of test results, the deviation of fuel consumption per hundred kilometers under two test methods was 0.1497%; but the deviation of emission results under two test methods were higher, the consistency between two test methods was poor, the deviation between two test methods were about 5%-20%. The emission results of test vehicle under on-road test condition were worse than those under heavy-duty chassis dynamometer test condition. But the test results of two test programs had better correlation, the correlation coefficient was 0.9986.