US Patents:   5,734,217 6,157,175 6,700,214 6,700,802. The patents cover the generator, bi-directional power supply, and the system architecture. The AuraGen is a solid rotor axial flux induction machine, composed of two stators and a solid rotor sandwiched between the stators.  The stators are made form a steel ribbon with copper windings. The rotor is made from a dual casting of steel and aluminum. The AuraGen is an axial gap induction machine, rather than a "squirrel" cage radial gap machine. Complete with a disk shaped rotor.

The current in the stator coils create a magnetic field in the gap as shown.  This traveling magnetic wave has a velocity v, amplitude Bo, and wavelength λ   (πDsave/ λ)=number of poles, Dsave=average diameter of stator)).  The magnetic field creates an accompanying wave of electric fields (EMFs) at right angles.  The electric wave amplitude is calculated from Boω/k=Ev, where ω is the angular frequency in radians/seconds.The electromagnetic induces

 

currents to flow in the rotor conductors according to Ohm’s law for bulk material JE, where J is the current density, σ is the bulk conductivity and E is the electric field. The current density J interact with the magnetic fields. According to Lorentz’s law; there is a resulting force per unit volume on the bulk rotor material of F=J x B.  What remains to understand is how much current is needed to flow in the stator coils to produce the magnetic wave with amplitude Bo.  The result can be computed using Ampere’s law ∫H.dl =current encircled. To summarize there are several key advantages to an axial symmertric design which are: (i) shorter flux return paths, (ii) much smaller total rotor volume, (iii) shorter stator coil end turns, (iv) symmetry keeps magnetic density more uniform throughout magnetic loop, (v) plane of symmetry with two stators reduces volume where useless leakage can exist and, (vi) symmetry and geometry permit use of solid steel in rotor without efficiency penalty.