Research On Flywheel Energy Storage System Based On DC/DC Converter With Integrated Magnetic Structure

Affected by many uncertain factors,a lot of problems such as power vacancy,imbalance between supply and demand,power quality decline will appear in micro grid.At present,the main way to solve the problems above is to configure uninterrupted power supply(UPS)in the micro grid.But the chemical storage battery adopted in the traditional UPS,is not applicable for the frequent cycle of energy storage and release,and it is service life will decrease sharply.The Flywheel Energy Storage System(FESS)has the characters of short discharge time and large discharge power,which will promote the power reliability.Therefore,the energy converter and motor control strategy for FESS are discussed strictly in the thesis.The thesis discusses situation at home and abroad is discussed for the FESS.The energy conversion part and energy storage part are included in the FESS.The bi-directional DC/DC converter is a structure which the discrete magnetic are integrated into one magnetic core via magnetic integration technology.The converter has good personalities of less magnetic elements,small occupied space and low current ripple;it also is applicable for high power applications.Secondly,the energy storage system is analyzed from the structure and the principle in detail.To realize the control strategy for charging and discharging is the key part in the energy storage system.When charging,the control algorithm for the driving motor is implemented based on rotor magnetic field vector control.However,when discharging,the voltage close loop control is adopted to stabilize the voltage in the DC side.The qualification of the technical parameters is studied emphatically;the magnetic integrated bi-directional DC/DC converter is manufactured as well.Finally,the simulation experiments are carried out for the whole FESS.The results show the control strategy for charging and discharging which is selected in the thesis has good control performance.The charging time is short,however,when discharging,the DC side voltage of the flywheel deceleration is stabilized and the voltage ripple is small.Compared with the traditional converters,the magnetic integrated structure converter has advantages of small volume,light weight,low cost and good economy.The FESS achieves the good performance including the ZVS,the reduction of operating cost,the current ripple is reducedeffectively as well.