Abstract: An inertial energy storage device including a synchronous rotary electrical machine for bidirectional conversion between mechanical and electrical energy including: a stator having two axially spaced sets of circumferentially spaced teeth; field excitation means disposed on the stator to provide an axially polarized magnetic field; stator windings including a plurality of coils, each of which surrounds at least one tooth from each set; and a rotor having a plurality of circumferentially spaced teeth facing the stator teeth, and a circumferential flywheel mass radially spaced from its rotational axis; and a motor control circuit including sensor means for sensing the position of the rotor relative to the stator; means, responsive to the sensor means, for generating a waveform for driving the machine when it is operating as a motor; a voltage control circuit for controlling the amplitude of the waveform for driving the machine; and a current control circuit for controlling amplitude of the current provided to t

Abstract: An optimum efficiency control system for a variable torque/speed rotary a.c.