Computer Aided Match Method for Matching the Electrical Motor and the Gearbox of the Pure Electrical Vehicle - Advanced Research on Computer Education, Simulation and Modeling - page 11

It is shown in Fig. 8 that the maximum actual power is 18.9kw, so it can suit the
required power.
Then the mapping characteristics of the motor should be plotted. There are two
kinds of mapping characteristics. The first kind of mapping characteristics whose
vertical axis is torque is shown in Fig. 10. To draw this kind of mapping
characteristics, a matrix which includes the output torque and the efficiency in
different pedal voltage and different speed is calculated using the fitted output torque
function and the fitted efficiency function firstly, then the mesh grid is established
using the “meshgrid” command and the grid is assigned using the “griddata”
command, then the mapping characteristics could be drawn using the “contour”
command. The second kind of mapping characteristics whose vertical axis is pedal
voltage is shown in Fig. 11. To draw these kind of mapping characteristics, a matrix
which includes the efficiency in different pedal voltage and different speed is
calculated using the fitted efficiency function firstly, then he mapping characteristics
could be drawn using the “contour” command.
Fig. 10. Mapping characteristics 1 Fig. 11. Mapping characteristics 2
The efficiency of the motor is 80% within the innermost scope of Fig. 10 and
Fig. 11. It can been seen that the high efficiency area of the motor is wider than it of
the engine.
4 Computer Aided Matching Method for the Motor and the
Gearbox
Once the motor performance had been analyzed, the maximum ratio, the minimum
ratio and the gears number could be designed under the help of MATLAB.
To improve the power performance and economy synthetically, the motor should
work in the high efficiency area and fulfill the required power. So the motor speed
while the maximum speed is chosen in the speed scale in which the motor power is
greater than17.8kw and the speed scale in which the efficiency is higher than 80%.
Then the 2350rpm is chosen. The proportionality between 2350rpm and 100km/h
which equals 2.631 is chosen as the minimum ratio of the gearbox.