We all know that the range of electric vehicles is now encircled. If there are no 600 or 700 kilometers, you are embarrassed to say it is pure electric. So the question is, how does this range come about? Let’s study it together.
The evaluation standards for range of electric vehicles and fuel vehicles are the same. Currently, the mainstream international evaluation standards include foreign NEDC (New European Driving Cycle) and domestic CATC (China Automotive Testing Cycle).
1. NEDC working conditions
In short, it is a speed-time curve:
Turn off the air conditioner between 20-30 degrees ambient temperature, professional veteran drivers step on the accelerator and brake according to the curve (±2km/h) in the figure above, and what they get is the fuel consumption/power consumption of the "Ministry of Industry and Information Technology Comprehensive Work Conditions". In order to avoid traffic jams and other problems encountered in real environments, the power consumption under NEDC operating conditions is measured through the "drum rotation test". On the drum test bench, the vehicle simulates the loading of real driving resistance, but no actual movement occurs.
2. Limitations of NEDC
China introduced NEDC working conditions, which is equivalent to unifying the "weights and measures" of fuel consumption/power consumption testing. This change from scratch not only facilitates consumers to compare horizontally before buying a car, but also makes technological competition among car companies more fair. However, the limitations of NEDC operating conditions are also very obvious:
only considers "driving habits" and "traffic conditions" and does not consider "air conditioning power"; the straight acceleration and deceleration and uniform speed curves are far from the real situation; especially for electric vehicles: uniform speed curves, it is easy to calibrate a very efficient braking feedback strategy.
3. Development of new working conditions
NEDC working conditions originated in Europe, and have realized the problem and implemented reforms. From the launch of the agenda in 2008 to its official implementation in September 2017, it took 9 years for United Nations Economic Commission for Europe and EU (EU) to complete the WLTC operating condition (Worldwide Light-duty Test Cycle)
After the WLTC operating condition is put into operation, there is still a three-year transition period from 2017 to 2020. WLTC will not be officially supported in 2020.
Compared with NEDC, WLTC operating conditions are more "real" and more demanding.
According to Peter Mock and others' research, the WLTC operating conditions will be 5.7%-7.7% higher than the average carbon emissions of NEDC operating conditions (carbon emissions correspond to fuel consumption/power consumption), which is closer to the actual driving data.
4. China Working Conditions (CATC)
was led by China Automobile Research Center and traveled more than 41 representative cities. A collection fleet of 3,832 vehicles was established, covering traditional passenger cars, light commercial vehicles and new energy vehicle , and about 32.78 million kilometers of vehicle sports characteristics, power characteristics and environmental characteristics data were collected. Based on this, CLTC China Working Conditions (ChinaLight-duty vehicle Test Cycly) was compiled.
5. The origin of CLTC operating conditions:
For passenger cars, it should be called CLTC-P (China light-duty vehicle test cycle-passenger), which is part of CATC. CLTC-P is a standard operating condition defined by 41 cities, 3,832 vehicles, accumulative 32.78 million kilometers, and 2 billion GIS traffic low-frequency dynamic big data. CLTC more truly reflects the working conditions requirements with Chinese characteristics, including a more reasonable definition of average speed and maximum speed, a wider driving conditions, a more reasonable parking mode ratio, and a richer dynamic acceleration and deceleration conditions.
CLTC-P cycle test method:
CLTC-P cycle operating conditions include three speed ranges: low speed (1 unit), medium speed (2 units) and high speed (3 units). The working time is 1800s, the cumulative mileage is 14.48km, and the maximum speed is 114km/h. The difference between
CLTC-P and NEDC:
CLTC-P has added a wider range of road conditions information: urban working conditions, suburban working conditions and high-speed working conditions, with a cycle time of 1800s; but the high-speed part takes up the minimum time, and the maximum speed and average speed are the lowest.Therefore, CLTC-P has more "care" for pure electric vehicles than in the past. Not only does electric vehicles consume 0 energy during parking, but they can also recover kinetic energy during driving. Therefore, the CLTC-P cruising range will be longer than NEDC.
Through the above introduction, you have a certain understanding of the range standards of electric vehicles.
