- 學位論文
複合輪胎力估測器於多動力馬達電動車驅動力矩分配策略之整合應用
Application of a Composite Estimator of Tire Force to the Driving Torque Strategy for an Electric Vehicle Driven by Multiple Motors
摘要
本研究提出一新型輪胎縱向力複合估測法，整合單輪分析及整車分析兩種不同的估測方法，並以本實驗室之多動力馬達電動車作為架構，實車採用15-kW直流無刷馬達搭配傳動齒輪箱，作為前輪之間接驅動動力源；後輪則由兩顆7-kW永磁同步馬達置於輪內，作為後輪之直接驅動動力源。此多馬達之動力架構能藉由操作各馬達的輸出力矩於高效率區間，達到提升整體行車效率與續航力之效果。而本研究係以本實驗室之電動車所配置的感測器，設計一套估測輪胎力(F_x,F_y,F_z)的估測器，進而使節能策略及安全策略能實行在實車上，而不單單只有在電腦模擬上完成，此估測器在行車過程中將提供估測值給整合車身穩定控制做判定依據，並根據駕駛者的油門及煞車命令，即時分配各馬達之驅動力矩及回充煞車力矩，以將各馬達持續操作於高效率區域，使行車時能在滿足駕駛者的加速性需求下，將行車效率最佳化，並且避免輪胎打滑與轉向失控的問題。 本研究以模型迴路(model-in-the-loop, MIL)驗證輪胎力估測器及力矩分配策略之性能，將車輛模型建置於CarSim之中，並設計輪胎力估測器以提供數據給控制策略進行運算，實驗結果顯示，其確實能在不失駕駛者對車輛動態之需求與行車安全為前提下，在加速、煞車、直行以及轉向操作時，即時的分配馬達力矩以達到節能行車之效果，而複合輪胎縱向力估測器之估測值明顯優於以單輪受力圖為基礎設計之估測器，而誤差改善的幅度達到60%~97%，尤其在前輪(左、右)皆有著更加顯著的差異，並在導入數值給車身穩定系統時，能達到更符合預期的行車結果。
並列摘要
This research proposes a new approach of estimator of tire force for electric vehicle (EV), which combines two different ways of estimating tire longitudinal force. The two methods are based on different analytical methods. The normal tire longitudinal force estimation analyzes single wheel model, but composite estimation analyzes not only tire model but also vehicle model. This composite estimator system is based on the powertrain of EV consists of three motors: a 15-kW front traction motor with gearbox and two 7-kW in-wheel motors installed inside both rear wheels. This configuration not only provides the vehicle good performance for planar motion control, but also improves driving efficiency of vehicle by driving and regenerative braking torque distribution of three motors. This research is found upon the sensors which configured in the EV of this laboratory to design an estimator system which can provide parameters to the distribution strategy of energy conservation and security. This estimator provides data to distribution strategy and allow it to calculate each torque of motors according to driver’s order. The strategy will adjust torque command of motors by particle swarm optimization (PSO) that makes motor operate in high efficiency region The torque distribution algorithm can improve driving efficiency by minimizing each instantaneous cost power and maximizing each instantaneous recovery power. In addition, in order to enhance the safety of vehicle driving, this research further develops the strategy by integrating electronic stability program (ESP), which is composed by slip ratio controller (SRC) and direct yaw-moment controller (DYC). Finally, this research verifies the accuracy of estimator and distribution strategy by model-in-the-loop (MIL) simulation. The vehicle model is designed from the software CarSim. Experimental results show that the composite estimator can calculate the values more accurately than traditional estimator, which can make ESP work more effiecntly than before. According to this data, the torque distribution strategy can ensure the driving safety by ESP and save energy when EV is either driving or braking on straight or curve roads.