# Research on Brake Energy Recovery Strategy Based on Working Condition Identification
## 5 Simulation Analysis
### Comparative Analysis of Simulation under Synthetic Cycle  
The synthetic cycle includes urban congestion, urban smooth, suburban, and highway conditions, with more aggressive driving behaviours, including higher rates of acceleration and deceleration. The entire cycle lasts for a total of 1800 s. Figure 19 shows the working condition identification results for the synthetic working conditions in the simulation process, and the accuracy of the identification results is 98.76%.  
Figure 20 shows the working points of the electric motor during braking under synthetic conditions, and it can be seen that, under synthetic conditions, the approximate distribution of the working points is consistent with that of the C-WTVC cycle, indicating that the strategy in this paper is highly adaptable to working conditions.  
Figure 21 shows a comparison of the total energy consumed and energy recovered for braking in the three load states under a synthetic cycle, from which it is clear that the strategy of this paper recovers more energy at any load.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Payloads** & **Projects** & **Condition** & **Fuzzy Control** & **Fixed-Ratio** \\  & & **Recognition** & **Strategy** & **Strategy** \\ \hline \multirow{4}{*}{Empty} & Proportion of high efficiency (\%) & 89.2 & 67.5 & 67.3 \\  & Energy consumption (kJ) & 6795.37 & 6795.37 & 6795.37 \\  & Energy recovery (kJ) & 4215.17 & 3132.67 & 1533.04 \\  & Energy recovery rate (\%) & 62.03 & 46.1 & 22.56 \\ \hline \multirow{4}{*}{Half} & Proportion of high efficiency (\%) & 88.1 & 68.6 & 67.9 \\  & Energy consumption (kJ) & 7943.62 & 7943.62 & 7943.62 \\  & Energy recovery (kJ) & 5253.11 & 3838.35 & 1834.98 \\  & Energy recovery rate (\%) & 66.13 & 48.32 & 23.1 \\ \hline \multirow{4}{*}{Full} & Proportion of high efficiency (\%) & 89.6 & 69.1 & 68.8 \\  & Energy consumption (kJ) & 8941.43 & 8941.43 & 8941.43 \\ \cline{1-1}  & Energy recovery (kJ) & 6227.71 & 4578.01 & 2092.29 \\ \cline{1-1}  & Energy recovery rate (\%) & 69.65 & 51.2 & 23.4 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Comparison of simulation results under C-WTVC cycle.  
Figure 19: Synthetic cycle category recognition effect.  
Figure 21: Comparison of energy consumed and energy recovered under synthetic conditions.  
Figure 20: Comparison of electric motor working point distribution under synthetic conditions.  
Table 8 shows the simulation results for the three loads under synthetic conditions, from which it can be seen that the energy recovery of the strategy in this study was improved by 34.2%, 37.4%, and 31.3% compared with that achieved with the fuzzy control strategy, and by 206.3%, 218.5%, and 197.2% compared with that observed with the fixed-ratio strategy, respectively, under empty, half, and full loads. It can be seen that the regenerative braking strategy based on condition identification resulted in a much higher braking energy recovery than the fuzzy control strategy and the fixed-ratio strategy in both the C-WTVC and synthetic cycles, showing the superiority of the strategy in this paper.