Research On Vibration Suppression Of Centripetal Force Type-magnetic Bearings-rotor System For Vehicle Flywheel Battery

With the aggravation of energy shortage and environmental pollution,it is an inevitable trend for electric vehicles to replace the traditional oil-powered vehicles.At present,electric vehicles are gradually accepted by the public,but people put forward higher requirements for them,such as cruising ability,safety and practicability.Power batteries have become one of the major problems limiting their wide application.There are many kinds of power batteries in the market,among which the flywheel battery stands out with its advantages of pollution-free,energy utilization efficiency,high service life and so on.The application of flywheel batteries in electric vehicles will be affected by some factors such as working conditions,suspension and uneven road surface.As the support system of vehicle flywheel battery,magnetic bearing plays an important role in the safety and stability of vehicle flywheel battery.Therefore,there are strict requirements for magnetic bearing topology design,dynamic modeling and control algorithm research.In this thesis,topology design,rotor dynamics modeling,control algorithm,stability and robustness of the vehicle flywheel battery support system are studied.The main work of this thesis is as follows:Firstly,the thesis introduces the research background of the vehicle-mounted flywheel battery.Then the working principle and key technology of flywheel battery were introduced in detail.At last,the research status of flywheel battery at home and abroad is described,in which the development status of control algorithms for gyroscopic effect and synchronous vibration suppression of magnetic bearings is described emphatically,and the shortcomings of the current control algorithms are summarized to illustrate the purpose and significance of the research in this thesis.Secondly,in order to improve the anti-interference ability of the suspension bearing-rotor system under working conditions,a new spherical magnetic bearing with centripetal force was proposed.The structure and working principle of spherical magnetic bearing with centripetal force are introduced.The direction of the magnetic circuit of the magnetic bearing is analyzed,and how the spherical structure can improve the anti-interference ability of the system is explained.Then the stability of the spherical rotor and the linearity of the suspension force formula of the spherical magnetic bearing are confirmed by the finite element analysis.The dynamics model of the suspension bearing-rotor system is established.Thirdly,in order to solve the problems of gyroscopic effect and synchronous vibration in the centripetal force type-magnetic bearing-rotor system when the speed increases,a control algorithm based on the golden frequency section point(where the golden frequency section point is a critical point to distinguish the low speed region from the high speed region)was proposed.The rotor speed was divided into two regions,and corresponding control strategies were proposed for different regions affected by gyro effect and synchronous vibration.Then,the simulation results show that the proposed control algorithm has better stability and robustness than the traditional control algorithm in the whole speed domain.Finally,the overall experiment scheme of spherical centripetal force type-magnetic bearing-rotor system is formulated,and the test bed is built.The hardware circuit design and software design of the experimental platform and the whole control system are introduced in detail.Then,stability experiment and robustness experiment are carried out to verify the feasibility and superiority of the control algorithm based on golden frequency section points.Stability experiments are divided into three parts: global vibration suppression at high and low speeds,synchronous vibration suppression and gyro effect suppression.At last,a conclusion is drawn by analyzing the experimental results.