| The rapid development of modern society is based on the energy consumption, and the consumption of primary energy spurred the development of new energy. However, the new energy which mainly contains wind and solar energy has the problem of intermittent and volatility. In order to connect new energy with power grid, it requires energy storage device of high efficiency. Among energy storage system, a lot of attention has been paid to flywheel energy storage system which has the advantages of high efficiency, long life, no pollution; and these advantages make it show a great pratical value in satellite system, distributed generation, FM peak shaving and rail transporation, etc.The flywheel energy storage system is a kind of electromechanical integration equipment with complex structure; it mainly contains flywheel rotor, motor/generator, magnetic suspension bearing, the power converter, vacuum equipment, cooling equipment and protect shell, etc. This subject mainly analysis and design a flywheel energy storage system which has the capacity of 1kWh. According to the design index, the shape and the material of the flywheel rotor are designed, and its size was calculated.For the motor/generator of flywheel energy system, its characteristics theoretically are analyzed, and its type is selected according to the practical application. Through professional software, the preliminary design of the motor is completed. And through the finite element software, the performance of motor is evaluated and the parameter of motor/generator is corrected and optimized many times until the parameter meets the performance requirements. Then, in view of motor/generator control strategy, the motor model just need a rotate speed feedback control, and the generator model need a voltage feedback to stabilize output voltage because the output voltage of generator decreases gradually as time goes by. According to the control strategy, the control circuit in different model of the motor/generator is designed, and the production and testing of circuit board is completed.For reducing the static power loss, five degree of freedom magnetic bearing technology is adapted to realize the rotor suspension without friction. And the basic structure of radial magnetic bearing and axial magnetic levitating bearing are introduced respectively, and their bearing capacity calculation formulas are given respectively. The thrust plate of axial magnetic levitating bearing is designed into the wheel hub because flywheel needs hub as the carrier during its rotation. Accordingly, the flywheel hub has two functions. The differential control strategy is adapted to achieve the rotor suspension in magnetic bearing technology; in this respect, the control principle of single freedom magnetic bearing technology is analyzed firstly, and then the suspension control of multi degree of freedom is realized on the basis of single degree of freedom control.The design of a simple three-dimensional model of flywheel energy storage system based on the size of the flywheel rotor, motor/generator and the magnetic bearing is accomplished. As a result of the processing and manufacturing of the composite flywheel rotor is relatively complex, a flywheel rotor of alloy steel material, uniform thickness solid disc shape and 100Wh energy storage is designed and manufactured in order to do suspension experiment and charging/discharging experiment.Finally, the experimental platform of 100Wh flywheel energy storage system is set up, and the experimental tests have been conducted. The values of static suspension, static suspension curve and dynamic suspension curve are measured actually depending on the position sensor. The motor accelerates rotation speed after achieving suspension of flywheel energy storage system, which realizes the energy storage of the flywheel. The actual rotation speed of the flywheel is detected and its energy is calculated. The waveform of drive signal is measured through detecting the outpin of driver chip of the drive circuit and the waveform of three-phase induction EMF is measured. And the energy storage of flywheel rotor is calculated actually. Not only these test datas, suspension curves and experimental waveforms verify the rationality and feasibility of this design, but also provide technical foundation, experience of design and experience of debugging for the design of larger capacity flywheel energy storage system in the next step. |
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