## 4 Validation and Discussion
### Experimental Results and Analysis  
According to the test, the energy consumption of the solar car was 1.063 kWh, and the solar panel charged 0.325 kWh. The test result is shown in Figure 12a. Simulation under the same working conditions was conducted. The solar car energy consumption was 1.008 kWh, and the solar panel charged 0.323 kWh, as shown in Figure 12b. \begin{table}
\begin{tabular}{c c} \hline \hline
**Category** & **Data** \\ \hline Temperature & 22 \({}^{\circ}\)C \\ Wind Speed & \textless{}0.5 m/s \\ Light Intensity & 9500–100,000 Lux \\ Road & Plastic Runway \\ Road Slope & \textless{}1 \\ Total Load & 600 kg \\ Cruising Speed & 40 km/h \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Experimental conditions. Figure 11: Physical test platform. From the test results and simulation results, the energy consumption of the actual solar car was 1.063 kWh and the simulated solar car was 1.008 kWh, with a difference of 0.055 kWh and an error of 5.17%; the actual solar panel charging was 0.325 kWh and the simulated solar panel charging was 0.323 kWh, with a difference of 0.002 and an error of 6.15%. However, at the same time, we observed that the actual solar car energy consumption curve fluctuates much more than the simulation curve, and ideally, the energy consumption curve obtained by cruising at 40 km/h should be a straight line, so we conducted further investigation. The results of simulated vehicle speed and actual vehicle speed are shown in Figure 13, the test results of solar panel output current and bus current are shown in Figure 14, and the simulation results of solar panel output current and bus current are shown in Figure 15.  
Figure 12: Comparison of test-simulation results: (**a**) Graph of test results; (**b**) Graph of simulation results. Figure 13: Simulated vehicle speed and actual vehicle speed result graph. From Figure 13, it can be seen that both the simulated speed and the actual speed fluctuated above and below 40 km/h after stabilization, and the degree of fluctuation of the simulation results was significantly smaller than that of the actual speed. During the acceleration process, both of them reached the expected speed within a short time; meanwhile, the actual and simulated bus currents were accompanied by a large pulse, and after the speed stabilization, the bus current value dropped back to the normal level. As seen in Figures 14 and 15, there was a periodic downward pulse in the solar panel output current value, and the current value was stable for the rest of the moments. By observing the test site we found that at one of the curves of the athletic track, there would be shade trees, so when the solar car passed quickly, there would be a substantial weakening of the light intensity, and the light sensor sensed the change and transmitted it to the DT model at the same time, thus causing a short sharp drop in the solar panel output current, and after passing the shade trees, it would quickly return to normal level. The actual bus current value oscillated violently in the process, on the one hand, because the solar panel output current dropped at the shade. As known from Section 3.1, the solar car's direct drive current came from the solar panel and battery, so in order to maintain the current speed, the bus current increased to compensate. On the other hand, because there are more curves on the athletic track, the motor power demand became larger at the curves, so the bus current value also increased. The bus current value of the simulation was more stable, because in the simulation process, the curve was not considered as a factor, and the DT model was simulated according to the linear motion, so its change was mainly influenced by the output current of the external solar panel. It can also be seen from Figure 15 that the bus current value would change with the output current of the solar panel in order to maintain the current speed. Figure 14: Solar panel output current and bus current test results. Figure 15: Solar panel output current and bus current simulation results.