Research On Hybrid Support System Of Energy Storage Flywheel

Flywheel energy storage system (FESS) has many advantages, such as high power density, high energy density, short charging and discharging time, no pollution, high efficiency, long life, etc. FESS is focused from energy storage technology. It is very possible to apply in electric vehicles, power grid and so on. FESS is helpful for energy conservation and improvement of environment. Today high power and high energy is the development direction of FESS. But the life of support systems falls because of the increase of size, weight and speed. The support systems stop the energy of the FESS from increasing. The bearing problems are urgent to solve. In this paper, some relating support issues on energy storage flywheels are researched on.There is an important problem in the vertical structure FESS. The weight of the rotor is too large. For the large static load of FESS, application of permanent magnetic unloading bearing is proposed to increase the life of mechanical bearings. Bearings with three different arrangements of magnetic poles are compared on force density. It is concluded that the unloading ability of radial magnetized structure is better. The radial magnetized unloading bearing for the rotor of FESS is designed. The relationship between the ratio of permanent magnet mass and structural parameters and the relationship between force density and parameters are studied with finite element method.The effect of dampers in support systems on the behavior of dynamics is studied. The mathematical model and the solution of the rotor-bearing problem of FESS are researched with Lagrange equation. The effect of damping on critical speed and damping ratio is studied with the model. The damping coefficient, location of single placed damper and double placed dampers are studied on the effect to the rotor vibration.The effect of structure and design parameters on of electromagnetic dampers in support systems on damping coefficient is researched on. In order to conclude easily and avoid 3D finite element calculations, the plate electromagnetic damper is studied instead of the actual columniform one. They are the same essentially. The relationship between damping coefficient and the frequency of vibration is studied. The frequency characteristic of damping coefficient is calculated and analysed.The linear voltage differential transformer (LVDT) as radial displacement sensors is designed and studied for the experiment of the support systems. The principle of LVDT is derived. The output voltage is calculated under the excitation of voltage sources and current sources. At last the parameters and output characteristics of LVDT are calculated with FEM.