Application of linear switched reluctance actuator in active suspension systems.

摘要

Electromagnetic active suspension system is attracting more attention as the developments in motor design, power electronics and modern control method. It is more energy-efficient with faster dynamic response, compared to the hydraulic counterparts. In this thesis, a novel configuration of linear switched reluctance actuator (LSRA) is proposed for the application in active suspension system. The robust construction, low manufacture and maintenance cost, less thermal problem, good fault tolerance capability and high reliability in harsh environments make LSRA attractive alternatives to permanent magnet actuator.;In order to determine the requirements on actuator design, the effects of suspension parameters are investigated by analyzing the frequency response. A LQR controller is developed and simulated with the quarter-vehicle model to obtain the optimal force requirement. By considering the requirements and constraints, a novel configuration of LSRA that comprising of four double-sided modules is proposed. The design procedure, ranging from the determination of basic actuator parameters to the calculation of actuator characteristics, is demonstrated in this thesis. The accuracy of analytical design is verified by finite element method. Besides, the longitudinal and transversal end effects of double-sided LSRA are evaluated by analyzing the sensitivities to translator position and excitation current.;To improve the actuator performance, a multi-objective optimization method to obtain higher average force, reduced force ripple and higher force density is proposed. The effects of stator and translator pole width on three optimization criteria and actuator volume are analyzed. Based on the optimized specification, a prototype of proposed LSRA was fabricated to verify the theoretical design.;Finally, an improved direct instantaneous force control scheme for four-quadrant operation is developed, which incorporates adaptive force distribution function (FDF), force estimation, hysteresis force controller and on-line determination of switching positions. By introducing the on-line estimated force of outgoing phase to FDF, the force demand of incoming phase is adaptively adjusted. Hence, the force ripple can be minimized over a wider range of switching positions. On the other side, the operation efficiency is improved by on-line optimizing the switching positions according to the force demand. The simulation and experimental results demonstrate the effectiveness of the proposed control scheme.