How do you develop control strategies for parallel hybrid powertrains?

Parallel hybrid control determines optimal torque split between ICE and electric motor to minimize fuel consumption while meeting driver demand. Strategies include: Rule-based (charge-sustaining thresholds, ICE efficiency islands), ECMS (Equivalent Consumption Minimization Strategy, real-time optimal), and Predictive/MPC approaches using route information. Key decisions: engine on/off logic (considering restart penalty), e-drive zones (low speed, deceleration), boost assist thresholds, regenerative braking blending with friction brakes, battery SoC management, and thermal constraints. Calibration balances fuel economy, driveability, battery life, and emissions across drive cycles (WLTC, real-world).