Lateral-torsional-pendulum coupled vibration mechanism and active torsional control method for range extender systems

As the core energy-replenishing unit of series hybrid electric vehicles (SHEVs), the range extender experiences inherent engine torque pulsations during start-stop and steady-state operating conditions. These pulsations induce intense lateral-torsional-pendulum (LTP) coupled vibrations through the mounting system, emerging as a critical bottleneck restricting overall vehicle NVH performance. Conventional isolated analysis methods for crankshaft torsional vibration and mounting isolation, alongside existing active torsional control strategies, frequently suffer from frequency-domain coupling conflicts between power generation and vibration attenuation. To address these issues, this study investigates an active torsional vibration suppression strategy for a specialized vehicle range-extender-mounting system, grounded in the underlying coupled vibration mechanism. First, a multi-degree-of-freedom (MDOF) lumped-parameter dynamic model of the system is established to elucidate the LTP coupled vibration mechanism, verifying the dynamic law that suppressing pure torsional vibration can synchronously mitigate lateral and vertical vibrations. Subsequently, based on a dual-loop motor control method oriented toward torsional vibration control, a parallel narrowband Filtered-x Least Mean Square (FxLMS) active torsional vibration controller with adjustable attenuation intensity is designed to specifically target the second and fourth dominant engine harmonic excitations. Finally, the performance of the proposed strategy is validated through numerical simulations and hardware-in-the-loop (HIL) semi-physical experiments. The results indicate that the proposed strategy achieves a maximum torque vibration amplitude attenuation of Change to 78.5% under steady-state conditions while maintaining superior convergence and robustness under dynamic variable-speed conditions. Concurrently, the lateral and vertical vibration amplitudes of the mounting system during start-stop phases are synchronously reduced by over 50%, effectively realizing the co-optimization of active torsional control and system-level NVH performance.