## 3 Energy Management Strategy
### Adaptive Equivalent Consumption Minimization Strategy with Target SOC  
#### 3.2.1 Target SOC Decision with Road Information  
The main purpose of determining the target SOC is to ensure that the battery does not overcharge or overdischarge by using the road information ahead. For example, a downhill road ahead may cause the battery to overcharge and not be able to charge all of the regenerative braking energy. In this case, you can drain the battery in advance to make sure it is fully charged. You may also encounter a situation where the vehicle is driving in HEV mode due to a low SOC on a road that can be driven in EV mode. Figure 11: Structure of the cooperative eco-driving guidance workflow. Figure 10: Visual guidance for cooperative eco-driving in the MotionDesk simulation. The estimated driving speed to calculate the SOC change on a road segment considers the speed limit and curvature of the road. It is assumed that vehicles travel at a constant speed on a road segment, with speed limited by the road. Therefore, the estimated average speed is as follows. \[v_{avg,seg}=\min(v_{lim,CSA},~{}v_{lim,road}) \tag{6}\]  
Substitute Equation (6) into Equation (2) to calculate the driving resistance \(F_{R,est}\). \[F_{R,est}=F_{roll}+F_{drag}+F_{grade} \tag{7}\] \[=-f_{roll}~{}mg\text{cos}\,\theta-0.5C_{d}~{}A\rho v_{avg,seg}{}^{2 }-mg\text{sin}\,\theta\]  
Assuming the vehicle is traveling at a constant speed, the tractive force \(F_{tr,est}\) can be expressed as  
\[F_{tr,est}=-F_{R,est} \tag{8}\]  
From the tractive force, we then calculate the estimated torque and angular velocity of MG1 and determine the estimated driving mode of the vehicle accordingly. \[T_{MG1,est}=R_{whl}F_{tr,est}r_{whl2 MG1} \tag{9}\]  
\[\omega_{MG1,est}=\frac{v_{avg,est}}{R_{whl}r_{whl2 MG1}} \tag{10}\]  
\[b_{mode,est}=\left\{ \begin{array}{ll}1~{},~{}~{}T_{MG1,est}>T_{EV,lim}( \omega_{MG1,est})\\ 2~{},~{}~{}T_{EV,lim}(\omega_{MG1,est})\geq T_{MG1,est}>0\\ 3~{},~{}0\geq T_{MG1,est}\end{array} \right. \tag{11}\]  
where \(T_{MG1,est}\) is the estimated torque of MG1, \(\omega_{MG1,est}\) is the estimated angular velocity of MG1, \(R_{whl}\) is the wheel radius, \(r_{whl2 MG1}\) is the gear ratio from the wheel to MG1, and \(T_{EV,lim}(\omega_{MG1,est})\) is the EV mode torque limit according to the estimated MG1 angular velocity. If the estimated driving mode \(b_{mode,est}\) is 1, it is HEV mode; if it is 2, it is EV mode; and if it is 3, it is regenerative braking mode. Next, we calculated the estimated SOC change of the battery, \(\Delta SOC_{bat,est}\). When the driving mode is EV or regen mode, only MG1 is used to drive or brake, and when it is HEV mode, the engine is assumed to be running at OOL torque, and the extra torque is driven by MG1. The angular velocity of the engine is the same as MG1. To summarize, the estimated usage of the battery is calculated from the tractive force. \(\Delta SOC_{bat,est}\) is calculated as follows. \[P_{bat,est}=\left\{ \begin{array}{ll}T_{MG1,est}\omega_{MG1,est}\eta_{e,avg}, ~{}~{}b_{mode,est}>1\\ (T_{MG1,est}-T_{OOL}(\omega_{MG1,est}))\omega_{MG1,est}\eta_{e,avg},~{}~{}b_{mode,est}=1\end{array} \right. \tag{12}\]  
\[\Delta SOC_{bat,est}=-\frac{P_{bat,est}~{}d_{seg}}{3600V_{bat}Q_{bat}v_{avg,est}}. \tag{13}\]  
where \(P_{bat,est}\) is the estimated battery power, \(\eta_{e,avg}\) is the average efficiency of energy transfer between MG1 and the battery, \(T_{OOL}(\omega_{MG1,est})\) is the engine OOL torque, \(V_{bat}\) is the battery voltage, and \(Q_{bat}\) is the battery capacity. The engine speed is equal to the angular velocity of MG1. Equations (6)-(13) are calculated for the three road segments ahead, which we define as segment 1, segment 2, and segment 3, respectively. \(\Delta SOC_{bat,est}\) for each is expressed as \(\Delta SOC_{1}\), \(\Delta SOC_{2}\), and \(\Delta SOC_{3}\). The target SOC is determined by reflecting \(SOC_{0}\), the battery charge status when entering the next road segment. Figure 12 shows the main idea of the target SOC decision.