1.1 Purpose of Research

With the rise of the concept of greenlogistics, the development of electric logistic vehicles has becomeincreasingly rapid. The purpose of this study is to design the general layoutof a 2-tone pure electric logistics vehicle which is suitable for urbanlogistics transportation and delivery, with the freight logistic vehicles onthe market as the reference and based on the driving conditions of urbanworking conditions.

1.2 Research Significance

In today’s society, car ownership continuesto go up, and traditional internal combustion engine cars are still themainstream of automobile products. However, at the same time, the exhaust gasof traditional internal combustion engine vehicles contains a large amount ofharmful gases such as CO#8322;, HC,NO and PM^[1]. Therefore, developing new energyvehicles has also become an important direction of the development of theautomobile industry, which has been widely concerned by the government and theindustry.

In recent years, the increasing scale ofe-commerce and online shopping in China drives the rapid growth of modernlogistics industry, and thus gradually drives the demand for urban logisticsvehicles. At present, most of the city logistics companies use theconfiguration which combines electric tricycles and traditional diesel trucks. Inthe process of distribution, electric tricycles generally have the defects oflow safety and insufficient cargo space, meanwhile, the high energy consumptionof traditional diesel trucks is always a big problem. In the process oflogistics, urban distribution belongs to the last kilometer service in thelogistics system. However, the continuous introduction of traffic restrictionsand “No Vehicle May Pass” policies in various regions makes urban distributionface the dilemma of “difficulty in entering cities, difficulty in loading andunloading, and difficulty in parking". In order to solve these problems,the electric urban logistics vehicle that has high safety, strong cargocarrying capacity and low energy consumption came into being and attractedattention from all sides which is suitable for commuting within the city.Hence, the country also issued relevant policies to support the development ofelectric logistic vehicles.

In accordance with the ministry ofcommunications, the national development and reform commission, ministry ofindustry and other 14 departments jointly issued "promote the healthy andstable development of road freight industry action plan (2017-2020)” in 2017,the country made clear that strengthening the management of city distributionvehicle technology, giving new energy distribution vehicle which is accord witha standard traffic convenient and comprehensively promoting the process ofcomprehensive urban freight vehicle electrification. In addition to the supportof national policies, local governments have also put forward the electriclogistics vehicle planning. It is understood that more than 20 provinces andcities have made clear the electric logistics vehicle operation plan. Electriclogistics car has the characteristics that travel is relatively fixed, themileage is focused on the short haul, use frequency is higher, concentratedcharging, etc, which has good economic, environmental protection, reliabilityin use process .That not only become the focus of the environmental protectionenergy conservation and emissions reduction enterprise models but also agreedwith country and province for the development of logistics industryrequirements. Therefore, the development of pure electric vehicle has greatsignificance for supporting the regional logistics industry chain and promotingthe development of local electric vehicle.

1.3 Research Status of Electric Vehicles at Home and Abroad

Although it has been 100 years since theappearance of electric vehicles, the technical level of electric vehicles hasbeen greatly improved in recent years due to the development of power batteriesand power electronic technology, as well as the national government'srequirements on energy conservation and emission reduction.

The development of pure electric vehicletechnology can be divided into two directions. First, some technicaldevelopment of electric drive, including power battery and electric drivesystem. The focus is on improving energy density, range and reducing costs. Second,Technology of body and electrical, which is the same as the development trendof traditional energy vehicles, mainly in three aspects: lightweight,intelligent and low carbon^[3].

(1) In the respect of power batteries,Ternary Lithium Ion batteries are widely used in pure electric vehicles. Atpresent, the battery manufacturers mainly produce NCM333 and NCM523 batterieswith high cycle life, stable charge and discharge and good safety, but lowenergy density. NCM622 batteries have higher energy density and have enteredthe material supply chain of some enterprises. The NCM811 battery, which is inthe research and development stage, is also expected to be put into use in thenear future. It has high energy density, good low temperature performance andlow cost, but its safety needs to be improved. The energy density of a singlebattery will advance from 200Wh/kg to 250-300wh /kg.

Internationally, the application process ofTernary Lithium battery in foreign countries is a little faster than that inChina. The NCM622 battery has been put into use and is carried on the BMW i3. Inaddition, the NCM811 battery is starting to be tested on a small range. In therespect of cylindrical batteries, domestic battery enterprises have started toconduct research and development and application of 21700 batteries. Domesticnew-energy vehicle batteries are expected to develop from 18650 to 21700. Theenergy density of the Tianpeng battery has reached 200~240 Wh/kg. Butinternationally, the 21700 battery developed by Tesla and Panasonic has amonomer capacity of 3~ 4.8ah and an energy density of 300Wh/kg. There is stilla considerable gap between the two.

(2) In the electric drive system, thetechnology of domestic vehicle drive motor is leading position in theinternational. The power density of the driving motor of passenger cars hasreached 3.3-3.6kw/kg (peak power/effective mass) and the maximum speed is above12800rpm. Commercial vehicle drive motor torque density up to 18Nm/kg, thehighest speed is up to more than 3500rpm, these indicators are stillcompetitiveness in the international market.

(3) In the automotive motor controllertechnology, the gap between domestic and foreign still exists, but has begun tonarrow. Under the standard module package, the power density of domestic motorcontroller has reached above 12kW/L, and the controller efficiency has reachedabove 98%, which is close to the level of Bosch motor controller in 2015. Whenthe customer requires customized packaging, the motor controller index datawill be reduced. However, domestic enterprises have developed customizedpackaged motor controller prototype with power density of 18kW/L, and the gapbetween domestic and foreign is gradually narrowing.