This document discusses flywheel energy storage systems. It describes the main components which include the flywheel, motor/generator, power electronics, magnetic bearings, and external inductor. It explains that the motor charges the flywheel by accelerating it to store kinetic energy, and acts as a generator to return the stored energy as electricity. Applications include electric vehicles, backup power systems, and industrial pulsed power. Advantages are high power/energy density and long lifetime, while disadvantages include potential hazards if the flywheel fails and short discharge times.

1. FLYWHEEL ENERGY STORAGE
SYSTEM

2. CONTENTS
• INTRODUCTION
• MAIN COMPONENTS
• WORKING
• APPLICATIONS
• ADVANTAGES AND DISADVANTAGES
• CONCLUSION
• REFERENCE

3. INTRODUCTION
• A Flywheel is simply amass rotating about an axis
• Flywheels store energy in the form of kinetic energy

4. • One of the promising technologies for replacing conventional lead acid
batteries and energy storage systems
• The built in motor provides the electrical input to accelerate the rotor
• Returns the electrical energy by using this same motor as a generator

5. MAIN COMPONENTS
There are 5 main components:
• Flywheel
• Motor/ generator
• Power electronics
• Magnetic bearings
• External inductor

6. FLYWHEEL
• flywheels store energy in a rotating mass of steel of composite material
• Mechanical inertia is the basis of storage method
• Use of motor/generator , energy can be cycled(absorbed and then discharged)
MOTOR/GENERATOR
• Permanent magnet(PM) machines have the most advantages, including higher efficiency and
smaller size when compared with other types of motors/generators of same power rating
• PM exhibit lower rotor losses and lower winding inductance
• The motor/generator is designed to be operated at high speed for minimum system size

7. POWER ELECTRONICS
• F E S S is the three-phase IGBT-based PWM inverter/rectifier
• The IGBT is a solid-states device with ability to handle voltages up to 6.7 kv, currents upto
1.2 kA
MAGNETIC BEARINGS
• Magnetic bearings consist of permanent magnets,
• Which support the weight of the flywheel by repelling forceand electromagnets are used to
stabilize
• The best performing bearing is the high-temperature super-conducting(HTS) magnetic
bearing, which can situate the flywheel automatically without need of electricity
• HTS magnets require cryogenic cooling by liquid nitrogen

8. EXTERNAL INDUCTOR
• The high speed PM offers low inductance
• The low inductances result in high total harmonic distortion(THD) which increases the
machine power losses and temperature
• Using an external inductor in series with the machine in charging mode is necessary to
reduce the THD and bring and bring it within an accepted range

9. WORKING
• The FESS is made up of a heavy rotating part, the flywheel, with an electric motor/generator.
• The inbuilt motor uses electrical power to turn at high speeds to set the flywheel turning at its
operating speed.
• This results in the storage of kinetic energy.
• When energy is required, the motor functions as a generator, because the flywheel transfers
rotational energy to it.
• This is converted back into electrical energy, thus completing the cycle.
• As the flywheel spins faster, it experiences greater force and thus stores more energy.

10. APPLICATIONS
• Hybrid and electric vehicles
• Light rail power
• Power quality/ UPS
• Industrial pulsed power

11. ADVANTAGES
• High power density
• High energy density
• The lifetime of the flywheel is almost independent of the depth of the charge and discharge
cycle
• No periodic maintenance is required
• Short recharge time

12. DISADVANTAGES
• Material limits at around 700M/s tip speed
• Potentially hazardous failure modes
• Short discharge time

13. CONCLUSION
• The state of charge can be easily be measured, since it is given by the rotational velocity
• Environmental friendly materials
• Low environmental impact

14. REFERENCE
• T. Aanstoos, J. P. Kajs, W. Brinkman, H. P. Liu, A. Ouroua, and R. J.
Hayes, “High voltage stator for a flywheel energy storage system,” IEEE
Trans. Magazine, vol. 37, no. 1, pp. 242-247, 2001.
• I. Vajed, Z. Kohari, L. Benko, V. Meerovich, and W. Gawalek,
“Investigation of joint operation of a superconducting kinetic energy
storage (Flywheel) and solar cells,” IEEE Transactions on Applied
Superconductivity, vol. 13, no. 2, Jun. 2003.
• B. Bolund, H. Bernhoff, and M. Leijon, “Flywheel energy and power
storage System,” Renewable and Sustainable Energy Reviews, vol. 11, no.
2, pp. 235-258, 2007.
• J. C. Zhang, L. P. Huang, Z. Y. Chen, and S. Wu, “Research on flywheel
energy storage system for power quality,” in Proc. International Conference
on Power System Technology, 2002, pp. 496-499. [
• J. C. Zhang, Z. Y. Chen, L. J. Cai, and Y. H. Zhao, “Flywheel energy
storage system design for distribution network,” in Proc. IEEE Power
Engineering Society Winter Meeting, 2000, pp. 2619-2623.