| Flywheel energy storage technology is a kind of technology that converts wind energy,solar energy and other renewable energy into the flywheel rotation kinetic energy and then store,with advantage of high energy storage density,short charging time,long service cycle,no pollution,and etc..And it is widely used in the new energy vehicles,Micro-network and UPS power supply systems and other fields.The friction loss from high speed rotation of flywheel is one of the factors that limits the development of flywheel energy storage technology,radial-axial magnetic bearings can achieve no friction between stator and rotor,and has the advantages of high speed,easy to control,and etc..Improving the energy efficiency and service life of the flywheel system.In this paper,a new type of structure with bearingless motor and3-degree-of-freedom(3-DOF)magnetic bearing is proposed as the bearing structure scheme of flywheel energy storage system.The axial space is greatly optimized and the system structure is simple.This paper mainly focuses on the structure scheme,mathematical model,control strategy and experimental design of the magnetic levitation support system of flywheel energy storage system.The main contents are as follows:Firstly,the research background of flywheel energy storage system is introduced and the key technology and application prospect of flywheel energy storage system is analyzed in this paper.The current situation of magnetic bearing support device and its control strategy is discussed in recent years.Research purpose and significance of this paper is clarified.Secondly,the basic operation principle and the working mode of the flywheel energy storage system are expounded.The advantages and disadvantages of several commonly used flywheel energy storage system support structures are presented.A comparative analysis of the magnetic bearing inner rotor and outer rotor structure dynamic performance and all kinds of magnetic bearings is also carried out in this paper.It is determined that the magnetic suspension bearing flywheel energy storage system adopts the outer rotor structure and 3-DOF magnetic bearing.This greatlyimproves the utilization rate of the axial space.The structure is relatively compact and the cost is relatively low.the magnetic circuit and structure of the 3-DOF magnetic bearing are analyzed.The working mechanism of the 3-DOF magnetic bearing is described.Thirdly,The equivalent magnetic circuit method is used to deduce the magnetic path of the 3-DOF magnetic bearing,The calculation formula and mathematical model of magnetic levitation force.And the parameters of the magnetic bearing including the magnetic pole area and the design of the ampere turns of the control coil,the design of the permanent magnet material parameters are designed,and then give the flow chart.as the non-linear characteristics of the 3-DOF magnetic bearing.The fuzzy sliding mode variable structure control strategy is proposed to design the synovial structure and the fuzzy variable synovial structure.And employs MATLAB software to simulate the 3-DOF magnetic bearing under the conditions of floating and interference.And make a detailed comparative analysis with simulation of the traditional sliding mode variable structure control strategy.Finally,the digital experimental platform of radial axial 3-DOF magnetic bearing is constructed.The software system,hardware composition and detailed experimental debugging scheme of the experimental platform are introduced,which will lay the foundation for the future debugging of the parameters;complete the fluctuation test and disturbance test of three-DOF magnetic bearing and make a detailed analysis of the test results. |
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