Inertia wheel

An inertia wheel comprising

• a flywheel having an adaptable rim of variable mass;
• a motor for peripherally driving said flywheel including
• a rotor fast with said flywheel and formed on said rim with a magnetic field of flux from said rotor formed across an air gap within which is a ring of an even number n of permanent magnets p of radial magnetization with alternating polarities, having a peripheral magnet width P.sub.p and a magnet pitch Pm linked by the relationship Pm=3P.sub.p /2, and
• a stator including a winding having sets of coils interconnected in pairs of ascending and descending turns of width P.sub.p /2 with the number of coils being three times the even number n of permanent magnets p divided by two and thereby the expression of number of coils equals 3np/2,
• said rotor located relative to said stator to place said winding of said stator where the radial magnetic field of flux of said rotor crosses the active turns of width P.sub.p /2 of said winding of said stator,
• switching means connected to said stator for switching the current on said sets of coils of said stator winding causing rotation of said rotor;
• a control means associated with said switching means for detecting the angular position of said rotor and said flywheel;
• magnetic bearings of the radially passive and axially active type mounted on said flywheel and said rotor and suspending said rotor on said flywheel;
• and
• an axial rate detector means for detecting the axial rate of said rotor connected to said stator relative to said rotor and an actuator connected between said rotor and said stator and associated with said detector means, each having redundant coils.