## 3 Results and Discussion
### Plowing Cycle
Figures 10-12 provide the operating points of the motors under the plowing cycle with different PDR values. To compare the influence of the same motor at different locations (sun gear or ring gear) on the economic performance of DICPS, the motors working points are put in the same figure, such as EM_S at PDR = 0.65 and EM_R at PDR = 0.35. Figure 8: Working mode of the DICPS. Figure 10: (**a**) Working points of EM_S at PDR = 0.8 and EM_R at PDR = 0.2; (**b**) working points of EM_S at PDR = 0.2 and EM_R at PDR = 0.8. Figure 9: Speed of motors during the plowing cycle. When the PDR was 0.8 or 0.2, the rated power of the motors in the DICPS was 24 kW and 6 kW, respectively. Figure 10a shows the working points of EM_S at PDR = 0.8 and EM_R at PDR = 0.2. The figure shows that the working points of EM_S and EM_R were distributed in a similar efficiency region, which means that they may have very close overall efficiencies. As can be seen from Figure 10b, EM_R at PDR = 0.8 had more working points distributed in the low-efficiency region than EM_S at PDR = 0.2. Therefore, PDR0.2 had a better economic performance than PDR0.8. When PDR was equal to 0.65 or 0.35, the rated power of the motors in the DICPS was 19.5 kW and 10.5 kW, respectively. Figure 11a shows the working point distribution of EM_S at PDR = 0.65 and EM_R at PDR = 0.35. It can be seen that the change in the motor connection position resulted in a great change in the working points' distribution. When the motor was connected to the sun gear (i.e., EM_S at PDR = 0.65), the working points were located in the more efficient region, but the number of working points was much lower than that of EM_R. As seen in Figure 11b, many of the working points of EM_S and EM_R were distributed in a similar area, but the remaining working points of EM_R were mostly located in the low-efficiency region. Comparing Figures 10 and 11, it can be seen that  
Figure 11: (**a**) Working points of EM_S at PDR = 0.65 and EM_R at PDR = 0.35; (**b**) working points of EM_S at PDR = 0.35 and EM_R at PDR = 0.65.  
the working points in Figure 11, located in the high-efficiency region, were obviously greater than the motors in Figure 10. Therefore, when the PDR was equal to 0.35 or 0.65, the overall efficiency of the DICPS was higher than when the PDR was 0.2 or 0.8. Figure 12 shows the working points of EM_S and EM_R at PDR = 0.5, and in this case the two motors were identical. There were few working points of EM_S, which indicates that the DICPS worked in mode M2S for most of the time. Most of the working points of EM_R were located in the high-efficiency region, which means that the DICPS had the highest efficiency at PDR = 0.5. In the case of PDR = 0.5, the parameter configuration with the highest overall efficiency was obtained through the calculation of EMS. Figure 13 shows the working points of EM_T in the SMPS, and that the operating points were located in the low-speed region, which lowered the efficiency of the motor and thus reduced the overall efficiency. It can be seen that there were more working points for EM_S and EM_R in DICPS, with different PDRs located in the high-efficiency region compared to EM_T in the SMPS. Therefore, in the worst case, the overall efficiency of the SMPS was lower than that of the DICPS. The main reasons for the inefficiency of the SMPS are that when the tractor is plowing, the speed is basically constant and the gear position is almost unchanged, which means that the working points of EM_T are completely determined by the tractor load and cannot be adjusted. In addition, the use of mechanical gearboxes can also cause a lot of energy loss. Figure 12: Working points of the motors at PDR = 0.5. The overall efficiency comparison under the plowing cycle is shown in Figure 14. It was noticeable that the overall efficiency values of the DICPS under three configurations are almost all greater than 85%. The overall efficiency was highest at PDR = 0.5, followed by 0.65, and PDR = 0.8 had the lowest efficiency.