## 3 Results
### Analysis and Synthesis  
#### 3.1.1 RB EMSs  
Although the first RB EMSs were never designed focusing on optimal power split, there are recent works focused on using optimization techniques to optimize the rules of commonly used RB control strategies (prevalent among commercial HEVs) such as the electric assist control strategy (EACS), power follower control strategy (PFCS) or charge depletion-charge sustaining (CDCS) strategy. In [15], a novel concept for RB EMS was developed: the threshold-changing mechanism. Predefined power thresholds instead of predefined states were used in the operating rules to achieve charge-sustaining operation of the HEV. Furthermore, in previous RB EMSs, the thresholds depended only on the battery state of charge (SOC) while, in this work, they depended on both the SOC and the engine speed. The proposed strategy was compared against the DP results, representing the global optimal solution, and the EACS results, representing the commercial solution. Furthermore, a simplified version of the proposed EMS was also developed to facilitate real-time applications and is included in the comparison. In [16], the rule-based EMS to be optimized was based on a fuzzy control. The fuzzy controller was designed to optimize the transmission efficiency instead of the classical EMS that focused on minimizing the consumption rate. As was proposed in [15], instead of proposing an EMS that depended only on SOC, the fuzzy controller considered both the engine torque and the SOC. A PSO algorithm was used to optimize the fuzzy controller membership functions. The results showed the comparison of the fuzzy EMS with and without optimizing its membership functions. It would have been interesting to add a comparison with the optimum strategy and with a common RB EMS. [PERSON] et al. [19] proposed an improved version of slope-weighted energy-based rapid control analysis (SERCA). SERCA had been applied to powertrains characterized by two operative modes solely. The proposed strategy allowed the application of this strategy to powertrains with more operative modes (multimode). The proposed strategy was compared to the optimum represented by DP and with a fast algorithm for multimode power-split HEVs, showing good quality results compared to the globally optimal solution. In [18], a blended EMS was proposed to overcome the limitations of the common CDCS scheme. Classical blended strategies relied on detailed or rough trip information to achieve near optimum energy allocation. The EMS proposed was a blended strategy that was able to overcome the poor adaptability and unsatisfactory real-time performance of typical EMSs with near-optimal fuel economy. Simulations were used to compare the proposed strategy with the offline optimal solution searched by DP and a typical commercial EMS represented by the CDCS scheme. The results revealed a good fuel economy compared to the DP and fast calculation speed compared to CDCS. Finally, in [17], the threshold values of a RB control strategy for multimode HEVs were optimized, combining an optimization algorithm with the minimum equivalent fuel consumption rate concept. The proposed control was compared with the fuel consumption obtained by the DP algorithm to verify the performance of the proposed control strategy and with the RB strategy before being optimized. The results showed that the fuel economy obtained was quite close to the optimal solution.