四輪車輪馬達直驅電動車之最佳驅動力矩分配控制

Optimal Torque Distribution Control of Electric Vehicle with Four Direct Driven Wheel Motors

郭家成(Chia-Cheng Kuo)

指導教授 ： 陳柏全

國立臺北科技大學/機電學院/車輛工程系所/碩士(2012年)

摘要

四輪車輪馬達驅動之電動車是屬於過度致動的系統，為了使車輛能保持良好操控性與穩定性，本文根據線性二自由度自行車模型，利用增益排程線性平方調整器設計電子穩定控制系統，以產生偏航力矩之參考命令。根據參考偏航力矩命令，在滿足駕駛者驅動/煞車需求下，利用控制分配法分配各輪的參考縱向輪胎力命令，並利用各輪的輪胎工作負載率，來設計相關的權重矩陣，以避免輪胎力飽和。接著利用摩擦相似轉換和合成滑差輪胎模型，配合道路摩擦係數估測器，以得到參考縱向輪胎力所對應的參考滑差；接著利用相位領先落後控制器，配合前饋補償器進行滑差控制，得到各輪馬達最佳驅動/煞車力矩。由模擬結果可得知，本文所提出的方法可達到偏航角速度追隨且兼顧車身側滑角限制之情況，並且在過彎時，能夠盡量避免車速降低，同時保有良好的操控性與穩定性，可以有效地提升電子穩定控制的性能。

關鍵字

車輪馬達 ； 線性平方調整器 ； 最佳力矩分配 ； 電子穩定控制 ； 控制分配

並列摘要

The electric vehicle driven with four wheel motors is an over actuated system. In order to maintain the maneuverability and stability, a gain scheduled linear quadratic regulator is used to design the electric stability control system to generate the reference yaw moment command based on the linear two degree-of-freedom bicycle model. Control allocation is used to distribute the desired reference longitudinal tire forces according to the yaw moment commend while satisfying the driver’s need for acceleration and deceleration. The associated weighting matrix is designed using the work load ratio at each wheel to prevent saturating the tire. The reference tire slip corresponding to the reference longitudinal tire forces can be obtained using friction similarity, combined slip tire model, and road friction coefficient estimator. The phase lead-lag control is used to design slip ratio control with feedforward compensator to obtain the optimal traction/braking torque at each wheel. Simulation result shows that the proposed algorithm can achieve yaw rate following and side-slip angle limitation when necessary. In addition, it can avoid speed reduction while maintaining the maneuverability and stability during cornering. Thus enhance the ESC performance effectively for the test maneuvers.

並列關鍵字

wheel motor ； linear quadratic regulator ； optimal torque distribution ； electronic stability control ； control allocation

參考文獻

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