# Model-Based Analysis and Improvement of Vehicle Radiation Emissions at Low Frequency
## 6 Conclusions  
This paper proposes a systematic method to solve vehicle-level radiation problems including the topological modelling approach, model-based analysis of technical factors and determination of engineering solutions considering untechnical factors such as cost and application difficulty. The application results show that the proposed strategy has the following advantages:  
1. By introducing the topological modeling method, the separate modeling and simulation can be achieved. Hence the faster simulation speed, the lower hardware requirement, and more accurate as well as more development efficient.
2. The influences of technical factors on the radiation problem can be evaluated quantitatively from the aspects of sensitivity and contribution by EWM.
3. The proposed hierarchical evaluation method can combine untechnical factors, i.e., application difficulty and cost, with the technical ones together to determine the final solution for the radiation problem. Some open questions about the detail problems are worthy of further investigation as follows:  
1. In this study, it is assumed the equivalent impedance of the circuit node is independent of its working state. This is no long valid if the circuit has high nonlinearities. If nonlinear components are used to describe the node, the equivalent interference cannot be solved by Equation (6) directly. Some analysis method for nonlinear circuits is required and need to be further studied;  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Advantages**} & \multicolumn{2}{c}{**Disadvantages**} \\ \hline \(\bullet\) & Modeling difficulty is reduced & \(\bullet\) & Circuit nodes should be linear and their characteristics should be independent of working states \\ \(\bullet\) & Network parameters can be obtained by a variety of methods independently & \(\bullet\) & Coupling paths in networks should be linear and passive \\ \(\bullet\) & Less engineering experience is required & \(\bullet\) & Some engineering experiences still are required to do the hierarchical analysis \\ \(\bullet\) & Both technical and untechnical factors are considered comprehensively & \(\bullet\) & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Advantages and disadvantages of model based analysis and improvement strategy.  
Figure 13: Improvement results of electric field at left side: (**a**) Simulation; (**b**) Experimental test.  
* Moreover, the equivalent impedance of the circuit node is measured under the state of power off. When the circuit is activated, how to measure the equivalent impedance is still a problem especially for the high power switching circuit;
* During the improvement process, it is possible to consider the effectiveness of the potential solutions quantitatively with the topological model;
* In this study, only the common mode interference is considered and how to model the differential mode ones need to be further studied.  
[PERSON] wrote the paper and provided the main idea, [PERSON] conducted the data analysis and modelling of EMI, and [PERSON] provided the experimental data. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the Open Fund of Chongqing EMC Technology Research Center under the grand 19 Akc6 and National Key R&D Program of China under grant 2017 YFB0102504.  
Not applicable.  
The study did not report any data.  
The authors declare no conflict of interest.