| Hybrid powertrain matching technology is one of the most important technologies during the hybrid electric vehicle development process. This paper was financially supported by the National Key Technology R&D Program," Universal Modular Hybrid Powertrain of Commercial Vehicles and Construction Machinery ", expounding the entire matching process from scheme establishing to prototype testing. The main works of this paper are as follows:1. Working Cycle Construction Based on Experimental MeasurementWorking cycle, known as the reference of developing new vehicles and new technologies, is mainly used for fuel consumption testing and emission testing of vehicles. In theory, working conditions vary with vehicles in different regions during different time periods. Namely, it means that there isn’t exist a standard working condition that can describe the work cycle of all kinds of vehicles in any regions during any time perfectly.In addition, working cycles of common road vehicles only contain driving cycles. Besides the driving cycle, the working cycle of the compressing sanitation truck studied in this paper also contains the loading cycle during which the compressing sanitation truck completes collecting and compressing sanitation. Up to now, almost all the researches about construction of working cycles are aiming at driving cycle construction, and there is no public research work on the construction of compressing sanitation trucks’work cycle.In view of the two reasons we talked about, the typical working cycle of the compressing sanitation truck was constructed. To collect the working condition data of compressing sanitation trucks, the paper developed an on-board remote monitoring system, which used the CAN bus and other sensors to collect the vehicle’s working state data transmitted to monitoring center through GPRS. The measuring area,the measuring road and the measuring time were programmed reasonably based on the features of Xi’an city’s roads and the compressing sanitation truck’s characteristics. Specifically, the measuring area covered the typical urban areas, including commercial districts, residential quarters and industrial zones. The measuring road went through urban main road, urban secondary road and outer ring road. The measuring time selected both traffic peak time and slack time. In this case,12,000groups of data were gained in total, in the tests extending792.3km during7days.So far, the existing researches have focused on Fragment Classification in kinematics, while few studies are taken up with Fragment Extraction. Therefore, this paper presents a two-stage clustering method in the process of generating the typical working condition on the basis of the test data, used to perfect the extraction process of kinematics fragments. To verify the effectiveness of the proposed method, this paper sorted the same test data using the proposed method and traditional method to build a typical working condition respectively. Then the two typical working conditions were compared with each other via methods of the scatter distribution, the probability density distribution, the joint probability density distribution, the modeling and simulation in turn. The comparison showed that the typical working condition applying two-stage clustering method had56.2%and80.1%improvements in the probability density distribution of the velocity and acceleration,29.9%improvements in the joint probability density distribution of the velocity-acceleration. Moreover, the fuel consumption of loading, accelerating, constant speed and decelerating phase increased respectively by0.71%,0.53%,0.77%,0.47%on the percentage, the differences between fuel consumptions of each stage and the measured fuel consumption improved by2.15%,1.24%,1.59%,12.86%,15.72%on the percentage.2. The Simulation Study of Hybrid Compression Sanitation TrucksCombined with the typical working conditions, the paper analyzed the structure and working process of traditional dynamic sanitation trucks to find out the basic cause of traditional dynamic sanitation trucks with high fuel consumption. There were two reasons why traditional dynamic sanitation trucks had high fuel consumption. First, the demands for power performance of driving condition and loading condition varied greatly. Second, the engine acted as the only power source for whole vehicle. In order to guarantee the normal work of the whole working conditions, the engine was demanded to meet the higher requirement for power performance, the one of driving condition. Consequently, the engine worked at a low load under high fuel consumption for a long time in loading condition, which led to the inefficiency of the whole working conditions. Hybrid technology had the native advantage of facing such problems:an integration of several power sources in essence, complementing every power source to achieve an efficient overall characteristic. Owing to multiple power sources in the hybrid powertrain, composition structure of powertrain had more schemes for supply. How to choose the optimal hybrid structure is the first problem faced in hybrid powertrain matching process.Referring to the actual structure of sanitation trucks and the structure classification of hybrid technology, four hybrid powertrain solutions applied to compression sanitation trucks were designed in this paper. Based on the demand for power assembly of sanitation trucks under driving conditions and loading conditions, the paper compared and analyzed the applicability of four solutions for compression sanitation trucks, and ultimately determined a prepositional motor single-axle parallel hybrid solution.It was demonstrated qualitatively that hybrid technology can improve the economy of sanitation trucks, combined with the structure of the single-axle parallel hybrid power assembly and the actual working conditions of sanitation trucks. In the absence of real vehicles, how to describe quantitatively the economy improved by hybrid technology became the second problem in the matching process of hybrid power assembly.The behavior of the static vehicle could not be simulated in Cruise. It meant that the loading conditions of sanitation trucks could not simulated in Cruise either. The second problem mentioned before had been solved through Cruise and Matlab/Simulink co-simulation technology, by which the whole working conditions could be simulated. Among them, the driving condition model was established in Cruise, the loading condition was established in Matlab/Simulink. Then traditional model of sanitation trucks was established and simulated. Finally the accuracy of the model was verified through the comparison between the simulated fuel consumption and the measured fuel consumption, results of the comparison showed that fuel consumption under driving condition deviated with a rate of8.09%, fuel consumption under loading condition deviated with a rate of3.97%, the total fuel consumption deviated with a rate of6.35%. The model had high accuracy. On the basis of traditional model of sanitation trucks, the power assembly was altered according to hybrid dynamic vehicles, while other parts were left unchanged, thereby, the hybrid dynamic model was established. As the typical working conditions acted as the target conditions, the traditional model and the hybrid dynamic model were simulated. The effect on the economy of hybrid technology was described quantitatively comparisons of the distribution of engine working points and fuel consumptions of the various stages. In driving conditions, the overall efficiency of the engine improved significantly:it was46%of engine working points less than210g/kw·h in hybrid dynamic system, while there was25%in traditional dynamic system. In loading conditions, fuel consumption of the engine reduced significantly: fuel consumption of traditional sanitation truck was1.87kg, yet0.96kg of hybrid scheme. Integrated the whole working conditions, hybrid dynamic system improved fuel consumption by25.8%.3. Study on Power Management of Single-axle Parallel Hybrid CSTAfter the structure and parameters of the hybrid system were determined, the efficiency of the hybrid system was directly influenced by the power management strategy, so, the matching of power management strategy is one of the most important processes during developing new HEV. Based on the fact that logic threshold control strategy can’t fit the change of all work conditions, global optimization control strategy unable to practical application and fuzzy logic control strategy hard to realize in embedded real time systems, this paper paid attention on instantaneous optimization control strategy based on minimum system fuel consumption rate.Combined with structure analysis of the hybrid powertrain and real work condition requirements, this paper analyzed the drive mode and energy flow of hybrid power train and acquired the energy transfer path of the powertrain. Referred to the definition of engine fuel consumption rate, this paper imported the definition of system fuel consumption rate and used this definition to explain the hybrid system’s fuel economy. Based on the works mentioned above, established the mathematical model of different drive mode’s fuel consumption rate and realized instantaneous optimization control strategy based on minimum system fuel consumption rate in Matlab/Simulink. Finally, verified the effectiveness of the strategy. The results indicate that, compared with the logic threshold control strategy, by using the strategy that this paper established, the fuel economy improves2.97%.4. Design of Single-axle Parallel Hybrid Powertrain Test PlatformDuring the development of hybrid electric vehicle, bench test is of great significant to shorten the period of vehicle calibration and help the developer to reduce the costs and risks of the development of HEV In this paper, based on the characteristics analysis of single-axel parallel hybrid powertrain, the single-axle parallel hybrid powertrain test platform was designed and constructed by using modular design method.Based on the structure analysis of the hybrid compression sanitation truck, designed a single-axle parallel hybrid powertrain test platform. Modular design method was used to realize this platform and this platform was divided into four modules:driver simulation module, powertrain module, vehicle resistance simulation module, data acquisition and control module. This paper developed a vehicle control unit that used in the test platform. This HCU used STM32F103MCU as its processer and uC/OS-Ⅱ as its operating system. The Function design, software design and realization of the four modules are respectively discussed. Finally, by changing the software of the test platform, realized function expansion of the test platform.Finally, this paper verified the hybrid power train’s effectiveness by taking road tests of real hybrid compression prototype vehicle. The results of the road tests indicates that the hybrid vehicle’s power performances, such as maximum speed,0-50km/h acceleration performance, maximum gradeability and so on, all meet the design target; the hybrid vehicle’s fuel economy improves33.78%, exceeds25%which is the design target. |
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