Abstract: A Coil Density Modulation (CDM) for the control of alternating current motors which controls the speed of the rotating magnetic field produced in the armature of the motor controlled. The magnetic flux wave components produced in the phases of the motor armature having the sine-approximated waveforms are synthesized by controlling the number of parallel turns of coils of the armature phase winding that are activated to produce magnetic flux by connecting them to a DC power source in sequences disclosed. Also the mechanical and electronic devices for the disclosed CDM method of motor speed control, together with the CDM motors for the CDM drive systems.