Jiuyu Du

Battery electric vehicle parameters design targeting to cost-benefit objective

Developing electric vehicle can reduce crude oil consumption and carbon emission sharply to resolve the problems of energy crisis and climate change of China. EVs require large batteries for energy storage, which affect electric vehicle cost, weight, and performance. More all electric range (AER) means more dispalcement of the fosill fuel, but lead to too expensive to afford for Chinas consumers. The electric vehicle design method to tadeoff between performance and cost is very valuable.This paper discussed the parameter optimization design method targeting cost-benefit objective. It analyses the impact of maximum speed, AER on energy efficiency and market competitiveness, based the survey data annalysis of vehicle kilometers daily traveled(VKDT), duty cycle analysis, etc.The mathematic model was proposed to account for the effects of additional batteries on fuel consumption, cost, etc. It can be find that when charged daily, AER of 50km or less, in China, using average small-capacity EVs is less expensive and releases fewer GHGs than conventional vehicles (CVs). By cost-benefit analysis, it can be concluded that for the first generation pure electric vehicle, the micro-size electric suitable for the first phase of development.

Review of electric vehicle technologies progress and development prospect in China

Developing electric vehicles (EVs) has been chosen as national strategy as solution to energy security and urban air pollution by China. China has invested much to develop electric vehicle technologies. In past 15 years, the EVs technologies have improved greatly, and in public serving field, the electric vehicle were used in large-scale. The traction battery and electric motor technologies were improved distinguished. By the EVs demonstration programs, the mainstream technology roadmap in line with Chinas national conditions is becoming gradually clear. In this paper, the progress of China EVs technologies breakthrough and industrialization, pushing policies (government and local government) were summarized. The progress on EVs demonstration program was reviewed and the effectiveness was evaluated. The technology roadmap of traction battery, fuel cell, and electric motor for EVs in past years was concluded. The different technological roadmaps were evaluated by effects in demonstration program. Based on the review of the progress of China EVs R&D and demonstration program, the existing problems and future challenges in EV development were put forth. And the future electric transportation in China was proposed, including electric powertrain technologies roadmap, electric car model strategy, EV industrialization strategy.

Parameters Optimization of PHEV Based on Cost-Effectiveness from Life Cycle View in China

Plug-in hybrid electric vehicle (PHEV) technology combining the merits of Battery electric vehicle (BEV) and Hybrid electric vehicle (HEV), has the potential to reduce greenhouse gas (GHG) emissions, and petroleum consumption in the transportation sector. However, the cost-benefit of PHEVs mainly determined by battery technology, optimal powertrain design, and vehicle kilometers daily traveled and charging habits. Targeting to cost-benefit, the optimal design method was presented, taking battery cycle life Vs DOD data, driving data, battery performance data into consideration. The method provided optimal vehicle designs to realize minimum life cycle cost, and maximum petroleum consumption under different scenarios. For A-segment equivalent PHEV (similar to a F3DM), under Shanghai urban driving conditions, it can be find that while PHEVs with present traction battery technology, 30 km AER was most life cycle cost-effective to obtain maximum petroleum displacement based on Shanghai driving data. Large capacity battery lead to petroleum displacement not so much as cost increased. At China electricity price off peak, Li-ion battery pack costs must fall below ¥2.0/Wh to be cost competitive with equivalent internal combustion engine vehicles (ICEs).

Study on energy management strategy based on DP for range extended electric bus in Chinese driving cycles

This paper introduces a systematic problem, which investigates the power management for the range-extended electric bus using dynamic programming. The Chinese typical city bus driving cycle and the bus driving cycle of Harbin City, Heilongjiang Province, China are expressed as the driving cycles in the DP process. The simulation model is established by referring to parameters of the REEB which is developed by Tsinghua University. And the power split ratio is introduced to analysis the simulation result. The DP results shows that the working points shows obvious rule by referring to power split ratio. The energy consumption and the fuel consumption are significantly lower than the conventional bus.

Energy Efficiency Oriented Design Method of Power Management Strategy for Range-Extended Electric Vehicles

The energy efficiency of the range-extended electric bus (REEB) developed by Tsinghua University must be improved; currently, the energy management strategy is a charge-deplete-charge-sustain (CDCS) strategy, which exhibits low energy efficiency on the demonstration model. To improve the energy efficiency and reduce the operating cost, a rule-based control strategy derived from the dynamic programming (DP) strategy is obtained for the Chinese urban bus driving cycle (CUBDC). This rule is extracted by the power-split-ratio (PSR) from the simulation results of the dynamic powertrain model using the DP strategy. By establishing the REEB dynamic models in Matlab/Simulink, the control rule can be achieved, and the power characteristic of powertrain, energy efficiency, operating cost, and computing time are analyzed. The simulation results show that the performance of the rule-based strategy presented in this paper is similar to that of the DP strategy. The energy efficiency can be improved greatly compared with that of the CDCS strategy, and the operating cost can also be reduced.

Multistage CC-CV Charge Method for Li-Ion Battery

Charging the Li-ion battery with constant current and constant voltage (CC-CV) strategy at −10°C can only reach 48.47% of the normal capacity. To improve the poor charging characteristic at low temperature, the working principle of charging battery at low temperature is analyzed using electrochemical model and first-order RC equivalent circuit model; moreover, the multistage CC-CV strategy is proposed. In the proposed multistage CC-CV strategy, the charging current is decreased to extend the charging process when terminal voltage reaches the charging cut-off voltage. The charging results of multistage CC-CV strategy are obtained at 25°C, 0°C, and −10°C, compared with the results of CC-CV and two-stage CC-CC strategies. The comparison results show that, at the target temperatures, the charging capacities are increased with multistage CC-CV strategy and it is notable that the charging capacity can reach 85.32% of the nominal capacity at −10°C; also, the charging time is decreased.

The Economic Analysis of a Plug-In Series Hybrid Electric Vehicle in Different Energy Management Strategy

This paper establishes the system model of a plug-in series hybrid electric vehicle, chooses typical city driving cycle of Chinese passenger vehicle as driving cycle and daily trip mileage of 150km. Two basic energy management strategies of CD-CS and Blended are used to compare the economic indicators of power and fuel consumption. On that basis, this paper summarizes up the fuel economy potential of the plug-in series hybrid vehicles. The simulation results show that, compared with the conventional fuel vehicle, in the driving cycle used in this paper, using CD-CS strategy and APU thermostat control method has the maximum efficiency. If not considering power consumption, the fuel saving ratio can reach 72.98%.

Comparison of different driving cycles control effects of an extended-range electric bus

In order to improve the economy in actual driving cycle of the electric bus, an extended-range electric vehicle (EREV) powertrain system evaluation method based on the characteristics of the driving cycle is proposed. The powertrain simulation model is established. This paper uses the energy management strategies of CD-CS and Blended to simulate and analyze the EREV in the driving cycles of Chinese city and Zhuzhou of Hunan province of China. The simulation results show that the EREV economies are different in different driving cycles. Compared with the conventional diesel bus, if not considering the power consumption, the fuel-saving ratio can reach above 30% in both city driving cycles.

The influence factor analysis of energy consumption on all electric range of electric city bus in China

For the electric city bus demonstration operating in Chinese city, based on establishing the system model, this paper uses constant speed and Hefei of Anhui province of China as driving cycles, mainly analyses the influence of the vehicle mass and the average power of the electric auxiliary on the endurance mileage and energy consumption. Simulation results show that, the electric bus studied in this paper driving at the constant speed of 30km/h, if the vehicle mass increases per 1000kg, the power consumption increases about 3%~4%. If the auxiliary power increases per 5kW, the power consumption increases about 15%~55%. In Hefei city bus driving cycle, if the vehicle mass increases per 1000kg, the endurance mileage decreases about 1km, but the power consumption increases about 3.5%. If the auxiliary power increases per 5kW, the power consumption increases about 22%.

Design method of energy management strategy for range-extended electric buses based on convex optimization

This paper presents an energy management strategy based on convex optimization algorithm for range-extended electric buses (REEB). The convex models of powertrain components are mainly constructed. Moreover, the energy consumption and components energy efficiencies are analyzed based on the energy flow method. The results show that, the fuel consumption of powertrain is 25.99 L/100km, the electrical energy consumption is 26.44 kWh/100km. The energy efficiency of the range extender, electrical power, and powertrain system are 35.04%, 70.13% and 28.30%, respectively. This strategy can be better applied to REEB energy management systems to meet the requirement of powertrain.