ABSTRACT
Electric machines are sets of magnetically or/and electrically coupled electric circuits with one (or more) movable element (rotor) which convert electrical energy into mechanical energy or vice versa (motoring-generating) via magnetic energy stored in their airgap (air space between the fixed part (stator) and rotor) and around electric circuit coils in air and in the magnetic laminated ferromagnetic core.
It is, again, based on Faraday’s Law, but this time for bodies in motion (rotor (s)). Electromagnetic torque is produced by the magnetic energy(co-energy) variation with rotor position.
Fix magnetic field (d.c. brush machines) and moving (traveling) magnetic field machines with passive or active rotor with a.c. or d.c currents are described by their torque formulae that bring up the theorem of frequencies (stator frequency=rotor motion frequency+rotor currents frequency) which secure ideally zero torque ripple in multiphase machines. Furtheron, linear electric motors and the recent breed of “flux-modulation” rotary electric machines principles with their torque are presented. A Summary and proposed problems (with solving hints) end this chapter of electric machine classifications (with 30 figures).
