## 5 Experiment
### Experimental Platform Construction  
The primary difference between the distributed permanent magnet direct drive belt conveyor and the traditional belt conveyor lies in the driving structure, which does not impose excessive requirements on the rollers and steering drum devices. To simplify the mechanical design of the experimental platform, permanent magnet direct drive motors are used to replace the rollers and steering drum devices. Additionally, to increase the friction between the conveyor belt and the permanent magnet direct drive motors and prevent belt slippage, the surface of the permanent magnet direct drive motors is covered with a layer of serrated rubber. The underside of the conveyor belt is treated similarly, which significantly enhances the adhesive friction generated between the two surfaces. The experimental platform is illustrated in Figure 25.  
Figure 23: Overall framework of the experimental platform.  
Figure 24: Block diagram of system control structure.  
Based on the review of the relevant literature [24; 25] and the actual conditions in the laboratory, an experimental platform for the belt conveyor, equipped with five evenly distributed permanent magnet direct drive motors, was constructed. The parameters of the components of the experimental platform are detailed in Table 3.  
It can be seen from Figure 26a that the five motors reach 200 r/min at 9 s. After the operation of the belt conveyor system gets stable and the load remains unchanged, the power distribution of each motor is redistributed at 12 s. Two motors continue to operate, and three motors operate as driving wheels in the conveyor belt. In the process of adjusting the power distribution of the belt conveyor, the speed of the belt conveyor fluctuates slightly. At 15 s, the motor power distribution is completed, the motor speed stabilizes, and the belt conveyor enters a stable operation again, thereby confirming the feasibility of the proposed motor power distribution strategy in this paper.  
As Figure 26b shows, within 12-15 s, the belt conveyor reduces the electromagnetic torque of the three motors under the control of the motor power distribution strategy, so that the remaining two motors can operate at a higher operating power. After 15 s, the electromagnetic torque of the two operating motors becomes stable, indicating that the power of the belt conveyor was maintained before and after the distribution.  
The power loss comparison curve of the new belt conveyor is shown in Figure 27. The red curve represents the power loss increase in the belt conveyor after motor power redistribution, while the black curve represents the power loss increase in the belt conveyor without power distribution. At 12 s, the power loss of the belt conveyor reaches 7.152 kW s. At 18 s, the values are 11.973 kW s for the red curve and 12.856 kW s for the black curve.  
Although there is a temporary increase in power consumption from 12 to 15 s due to the power redistribution among multiple motors, the overall power consumption from 12 to 18 s without power distribution is approximately 5.704 kW  
Figure 25: Experimental platform of distributed permanent magnet direct drive belt conveyor.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter (Unit)** & **Value** & **Parameter (Unit)** & **Value** \\ \hline Conveyor length (m) & 6 & Rated power of motor (W) & 200 \\ \hline Nominal speed (m/s) & 2.1 & Rated speed of motor (r/min) & 200 \\ \hline Belt width (m) & 0.4 & Number of motors (-) & 5 \\ \hline Slot angle (\({}^{\circ}\)) & 5 & Diameter of motor (m) & 0.2 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Specific parameters of belt conveyor experimental platform.  
distribution, it is approximately 4.821 kW\(\cdot\)s, resulting in an average power reduction of about 8%. Therefore, the new belt conveyor, when utilizing the multi-motor power distribution strategy, achieves a reduction in power loss.