In order to solve the problems of the increasing unsprung mass and the influence of the road excitation on the in-wheel motor (IWM), this paper puts forward two kinds of improved topology schemes. The bond graph (BG) and mathematical models of original and improved topological schemes are developed by using the BG theory. Based on the mathematical model, the final topology scheme is determined by the analysis of vibration energy transfer characteristics for the three schemes. It is further proved that the vibration energy analysis method is effective and complete in revealing the change of the system force and motion through the comparison analysis of the three kinds of topology scheme related to vehicle force and ride comfort index of motion variable. Furthermore, the optimal design is carried out for the determined topology scheme, which is aimed at minimum vibration energy delivered to the vehicle body. The comparison results before and after optimization show that: after optimization, the vibration energy delivered to the vehicle body has significantly decreased in the whole frequency range, and the vibration energy delivered to other components also decreased, which proved the correctness of the optimization method; and the comparison results of ride comfort index before and after optimization validate the effectiveness of the parameter optimization design based on the energy method. Finally, a structure design is provided based on the determined topology scheme. This paper provides an idea and method for the vibration suppression of the IWN driving electric vehicle (EV), while it can also provide some theoretical guidance for the design and optimization of the IWN driving EV.

The power grid is under pressure to maintain a reliable supply because of constrained budgets and environmental policies. In order to effectively make use of existing transmission lines, it is important to accurately evaluate the line capacity. Dynamic thermal rating (DTR) offers a way to increase the utilization of capacity under real-time meteorological data. However, DTR relies on a number of sensors and the cost is high. Therefore, a method of improving the utilization of capacity by quasi-dynamic thermal rating (QDR) is proposed in this paper. QDR at different confidence levels and time scales is determined through the statistical analysis of line ampacity driven by key parameters, and the key parameters is identified by control variate method. In addition, the operation risk and tension loss is evaluated. The results show that QDR can increase the utilization of line capacity and in the absence of along-line measuring devices, QDR is more accurate, reliable and cost-saving. The managers can determine the appropriate confidence level according to the operation risk and tension loss that the system can bear, and shorten the time scale with the permission of the operation and control complexity.

For an in-wheel-motor drive electric vehicle, the driving motors are directly mounted in the wheels. Using this chassis structure, the road excitation can cause a magnet gap deformation in the motor. The magnet gap deformation will lead to magnetic force which not only has a negative impact on vehicle dynamics but also affects the magnet gap deformation in turn. To further analyze the impact of the road and the magnetic force on the motor magnet gap, a test platform was built, and used to simulate cases of road and composite excitation. The results show that 1) road excitation can cause motor magnet gap deformation, and when the excitation frequency is increased for a constant amplitude, the deformation degree also increases. 2) For the same road excitation frequency, the deformation degree increases with the motor speed. This not only proves the existence of the magnetic force but also indicates that the size of the magnetic force is related to the motor rotating frequency. 3) A comparison between the simulated and experimental results not only confirms the validity of the theoretical derivation and analysis but also lays the foundation for subsequent vibration control of in-wheel-motor drive electric vehicles.

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