The induction motor is single-phase at supply voltage and can be connected to a source with alternating low voltage output. In order to realize an electric induction motor, it is very important to produce a rotating magnetic field. Pulsing and oscillating magnetic fields are spontaneously generated by coils fed with alternating electric current (AC). The magnetic field at a point near a coil with this power will oscillate in phase with the alternating current whose frequency is 60 Hz. If we consider a point on the axis of symmetry of a coil, there will be a magnetic induction oriented along the axis of the coil, which will have its intensity and sense varying harmoniously in time with period of 1/60 s.
For portable systems batteries may be used, however, more constantly the circuits need to be fed from the available AC power grid. In these cases, there must be a part of the equipment that converts the alternating waveform of the grid to energy of the continuous type. All electronic circuits require a source of electrical power to “feed” them. In general, this power source is a source of continuous voltage.