Research On Triple-Step-Method-Based Motion Control Of Automotive Permanent Magnet Motor

Energy shortage and environmental pollution are serious problems in our country.Improving the energy usage efficiency in automobiles is crucial to these issues.In worldwide,policies and regulations of energy and emission are introduced one after another to balance the increasing amount of automobiles and more serious environmental pollution.In 2013,the State Council approved a plan called “Made in China 2025”,in which the energy-saving vehicle,new-energy vehicle and intelligent network vehicle have been considered as priorities to upgrade and transform the vehicle industries.The plan repeatedly emphasizes that the production and control of vehicle motors as the core technologies must be developed to satisfy the development of the vehicle industries.Due to the new functions and requirements of the vehicle,the embedded codes of the controller are growing exponentially,which results in more difficulties in the design,calibration and verification of the vehicle-motor control system.The upgrade and update of vehicle-motor control system with cost-saving have been a critical issue in the development of vehicle electronic control system.Model-based design as a bond between the theory researches of the control algorithms and the system design has been highly expected as an effective means to solve the issue.It provides a general design structure applied to the vehicleembedded systems for the advanced control algorithms,which is helpful to deepen the understanding of the automotive system for the researchers and is also helpful to provide a theoretical guidance for automotive engineers.Vehicle motors,as the power system of actuators,start and stop frequently,which results in the motor commands complex and fast-changing.Therefore,the vehicle-motor control system should execute the commands with high precision and fast response.These characteristics such as high torque at low speed and wide speed range are preferred for the drive motor.This paper uses the newly developed nonlinear control theory,including triple-step nonlinear method and input-to-state stability theory,to address some motion control issues for automotive permanent magnet motor.The following issues are investigated: position control of electric clutch actuator,low-speed control with cogging torque suppression for drive motor,and torque control with direct flux control for PMSM(permanent magnet synchronous motor).Firstly,a three order nonlinear model is established for an electric clutch actuatorwith ball screw.Based on the triple-step nonlinear method,a general model-based controller is designed.Considering system modeling errors/disturbances introduced by the implementation of control law,the robust analysis is given and a conclusion that the whole system is ISS(input-to-state stable)with respect to the considered disturbance is reached.The model-based-design analysis method can effectively reduce the workload of the controller parameter calibration,the development cycle,and development cost.The designed controller is evaluated through simulations and experimental tests.Experimental results show that the proposed controller has better control performance which completely satisfies the stringent clutch operation requirements.Secondly,in order to improve the low-speed tracking performance,a novel observerbased nonlinear triple-step controller is provided.Considering that the cogging torque is a fast time-varying disturbance and changes harmonically,a nonlinear parameter-varying high-order system is established to model the fast-varying properties of cogging torque.Then,a reduced order nonlinear observer is designed to estimate the cogging torque,and the robustness analysis with regard to the uncertainties is given for the proposed nonlinear observer.The robustness condition is formulated as a problem of BMIs(bilinear matrix inequality)feasible solution.Thereafter,a triple-step nonlinear method is applied to derive a speed tracking controller,and then the robustness analysis against considered observation errors and lumped uncertainties is given.The proposed control scheme is verified through experimental tests,and the results show that tracking errors are substantially reduced at low speeds.Finally,a novel torque controller is designed directly from a coupling system model for PMSM by using a triple-step nonlinear method,in which the air gap flux control is considered explicitly.The designed torque controller can be applied to both constant-torque regions and constant-power regions.From the application point of view,the robustness analysis is discussed for the proposed controller.The proposed controller is evaluated through simulations and experimental tests.The results show that the proposed controller has a better control performance,and also show that the transition from the constanttorque operation region to the constant-power operation region is straightforward and effective during flux-weakening control.