The essential advantage of the three-phase asynchronous motor is the elimination of the commutator. The stator is composed of laminates, because a time-varying magnetic flux passes through them. A three-phase stator winding is placed on the poles or grooves. The rotor can be made as a cage or ring. The cage rotor is composed of thick aluminium, bronze, or copper rods connected together in a short way, with laminates filling the interior. The ring rotor is equipped with a winding through which the current supplied by brushes and rings from the outside flows. This design has the resistors located behind the rotor windings, providing the ability to alter operating conditions. In asynchronous motors, the magnetic flux is supplied to the stator by the field winding, but with a rotating voltage of variable amplitude and frequency, which must be derived from the DC voltage of the traction battery. Thus, the direct current from the accumulator must be converted to alternating current. by cyclically switching on thyristors, causing the rectangular waveform changes approximately to a sinusoidal one.

The stator winding is composed of at least three bundles, rotated by 120° from each other, and is powered by three-phase alternating current. Another alternative can also be 3n bundles (n is an integer), offset from each other by an angle of 120°/n. This winding produces a rotating magnetic field with a circular frequency of alternating current w, or for n bundles with a circular frequency w/n, meaning it rotates spatially relative to the motor housing.

Compared to a DC motor, an asynchronous motor is significantly smaller and lighter at the same power output, so a Power-to-weight ratio of about 1 kg/kW can be expected. Furthermore, the motor has a simpler design, is robust, maintenance-free, can be heavily overloaded and it can reach up to 20,000 RPM.

Both frequency and voltage must be variable to regulate the traction force and motor speed. Meeting these regulation requirements requires high power circuit costs. Recovery of energy during braking can be done with high efficiency.