Page - 91 - in Hybrid Electric Vehicles

Therefore, in this study, a rule-based control strategy for the coaxial power-split hybrid powertrain is designed and is shown in Figure 3. The entire rule-based control strategy is composedofa seriesmodecontrol andaparallelmodecontrol aswell asanHESScontrol.The seriesmode control strategy uses a power follower controlmethod shown in Figure 3. If the drivingpowerdemandof thevehicle is lower thana certainvalue, the systementers the series mode control. First, the required power of themotorPd is computed according to the system mathematicalmodel.Then, theoutputpoweroftheengineisdeterminedbasedonthegenerator efficiencymap.Themodifieddischarging/chargingpower is calculatedaccording to thediffer- ence between the present SOC and the target one. Subsequently, the requested power of the diesel engine isdeterminedaccording to thedefinedoptimal operation line (OOL)of the series mode control [31].Meanwhile, the engineon/off state is decideddue to the requiredpowerPd and the current SOC. If the engine state is on, the final required engine torque and speed are computedaccordingto therequestedpowerof theengineandthedefinedOOL. Figure3. Controlstrategyforthecoaxialpower-splithybridpowertrainwithanHESScomposedofaseriesmodecontrol andaparallelmodecontrolaswellasanHESScontrol strategy. A Hybrid Energy Storage System for a Coaxial Power-Split Hybrid Powertrain http://dx.doi.org/10.5772/67756 91