*3.3. Adaptive-ECMS*

The traditional ECMS method requires tuning the equivalence factor offline for every driving profile to ensure that the battery state of charge remains within the desired/operational limit. However, in real-world applications the future velocity profile is not known. Therefore, it is necessary to tune the ECMS factor in real time to ensure acceptable operation of the energy management system, especially when starting from an unfavorable initial condition. A-ECMS adjusts the equivalence factor based on drive cycle prediction, driving pattern recognition, or feedback from the battery state of charge [19]. In this work a modification of the approach that uses the SoC feedback [20] is adopted. The equivalence factor is adjusted as

$$a\_{\rm eq}(k) = \begin{cases} 0.25 & \text{if } \text{ SoC} < 40\% \\ 0.10 & \text{if } \text{ SoC} > 60\% \\ \max\left(\min\left(a\_{\rm eq}(k-1) + q\left(\text{SoC}(k) - \text{SoC}(k-1)\right), 0.25\right), 0.10\right) & \text{otherwise} \end{cases} \tag{9}$$

where *q* is a constant coefficient. The suitable sampling time for Equation (9) depends on the relative size of the energy storage and energy consumption. Simulations showed that a sampling time of less than 1 min can keep the SoC in 40–60% range for the tested drive cycle. However, a sampling time of 15 s was selected for the experiments for a tighter control over SoC, without adding a significant computational effort. Further investigations into sampling time dependence on drive cycle and vehicle parameters are left for future development. Figure 8 shows the A-ECMS implementation for hardware-in-the-loop experiments presented in the next section. *Pb* represents the battery power.

**Figure 8.** A-ECMS implementation for hardware-in-the-loop experiments.

#### **4. Experimental Setup**

## *4.1. Testbed*

Figure 9 shows a picture of the engine-dynamometer experimental testbed, which includes an AVL AC transient dynamometer, an instrumented 1.6 L Ford EcoBoost engine, and the power split supercharger by EATON. An AVL SESAM-FTIR emission measurement bench is used to measure exhaust gas species and calculate fuel flow rate along with a hot wire air flow rate meter. An AVL battery simulator is used to power the PSS and measure the motor current and voltage. A rapid prototyping electronic control system (RPECSTM) from Southwest Research Institute (SwRI) was used to integrate all engine controllers, the online energy management system, and implement real-time vehicle and driver models.

**Figure 9.** Engine-dynamometer experimental testbed.
