Study On The Flywheel Battery And It's Hybrid Maglev Control System

Flywheel Battery is a type of energy storage device which stores electricity in the form of kinetic energy of fast spinning flywheel rotor.The principle of flywheel battery is storing the surplus electricity by motoring the flywheel rotor,then retrieving the kinetic energy by decreasing the speed of flywheel rotor when electricity is required. Compared with the traditional chemical battery,flywheel battery has the merits of higher energy storage density,shorter charging and discharging period and longer life span etc.,which meet the demands for efficient energy resource as well as the environmental protection.The application of flywheel battery is promising in the field such as Hybrid Electric Vehicle(HEV),load leveling of electric power.A flywheel battery designed as the assisted power for the hybrid electric rail vehicle is proposed after an overall investigation on the key techniques about the flywheel battery design,wherein,a hybrid magnetic bearing for the above proposed flywheel battery is presented which incorporates both the electromagnetic control and permanent magnets,namely,the flywheel's axial freedom is actively controlled by electromagnet while the other DOFs are restricted by the permanent magnets in attractive mode,simultaneously,the permanent magnets also provide the bias flux for electromagnetic control.The formulae of magnetic force and it's stiffness are derived based on the fundamental theory about the permanent and electric magnetic bearing.The mechanical and electrical specifications are presented accordingly.The properties of magnetic force and it's stiffness of two types of permanent magnetic bearing configurations are compared using the Finite Element Analysis. Eventually,the curves for relationship between magnetic force vs.displacement & current are obtained.The magnetic bearing system is modeled through analyzing the force exerted on the designed magnetic bearing.Thereafter,the response of magnetic bearing to a step disturbance force is simulated under PD and PID controller,which provides some references for design of the actual controller.Finally,a controller combining both the fuzzy and PID control is presented and simulated.The simulation result shows that fuzzy-PID combined control is more robust to the disturbance force than the pure PID control. Eventually,a hybrid maglev(magnetic levitation) experiment is conducted respectively using the analog controller and DSP controller,in which,a pancake motor is used as the rotating driven device.The flywheel rotor is levitated stably under the said controller,which verifies the feasibility of the proposed maglev scheme.