The invention discloses an
energy storage flywheel device with a controllable motor or generator air gap
magnetic field. The
energy storage flywheel device is composed of a lower end bearing seat component, a lower end cover component, a motor
stator winding component, a motor
stator shell component, an upper end cover component, an upper end bearing seat component, an upper end sealing cover component, a
flywheel rotor, a pressing sleeve, a
rotary transformer, a nut, a
gasket, a screw and the like. In the device, the flywheel rotor is radially supported by mechanical bearings at the upper andlower shaft ends, and is supported by a pair of magnetic bearings in an axial direction; the charging / discharging energy conversion part of flywheel rotor is achieved by a generator with a controllable air-gap
magnetic field. The air-gap
magnetic field of the generator is controlled in real time by controlling the current of the annular
magnet exciting coil, the
counter electromotive force is improved by increasing the magnetic induction intensity, reduction of the
counter electromotive force caused by reduction of the rotating speed is restrained, and the
discharge depth of rated
power output of the
energy storage flywheel is increased. In a standby state, the current of the annular
magnet exciting coil is reduced, and the standby loss of the energy storage flywheel is reduced.