Innovation as a vocation

Servotecnica presents EMF motors based on the Liproka principle, featuring a rotor with a high number of poles.

EMF is a Turkish-German company with 55 years of business under its belt. The firm has developed an innovative line of synchronous motors based on the Liproka principle. Little known and almost never put to use until now, this principle is based on the concept of a synchronous motor with up to eight poles for the stator.
High energy efficiency. The innovation lies in the rotor, which features a high number of poles. High performance magnets are used to achieve a highly reliable magnetic flux. When a rotating magnetic field is applied to the stator, the field interacts with the one created by the magnets to create a sort of tug-of-war around the circumference. As a result, the rotor is set in motion in the opposite direction of the rotary magnetic field, but at a reduced speed, the ratio determined by the electromagnetic geometry and by the motor’s number of rotary poles.

The result is an “electromagnetic reduction” between the speeds of the stator and rotor. Since the former is directly proportional to the frequency generated by the transformer, the rotational speed of the rotor shaft can be precisely calibrated at any time. The motor can be controlled simply by adjusting the frequency, or by hooking up the motor with a feedback mechanism, just like a normal brushless motor, both in terms of speed and of position.
The resulting drive system is for all intents and purposes a gearless geared motor, but one that offers greater energy efficiency than a classic gear motor, and zero play. A traditional solution typically has 80% efficiency. With the EMF solution that goes up to 98%.

The energy lost in the copper is also decisively lower than that of a torque-based drive system. Thanks to a highly advantageous volume-to-generated-torque ratio, facilitated position control and low cogging with consequently enhanced speed consistency, these drives prove highly dynamic. With no reduction gear, the EMF motor is extremely low-noise and, most importantly, requires no assisted ventilation. These motors reach a maximum torque between 7500 Nm and 100 RPM
For closed loop applications this solution offers a complete range of feedback options, including incremental encoders, absolute encoders (Endat, SSI, single- and multiturn BISS) and resolvers.
Combined with Servotecnica drive systems, EMF motors enable having a single package with all possible fieldbus solutions (CanOpen, EtherCAT, ProfiBus, ProfiNet). They can be used in applications ranging from converting to flexographic presses, and from extrusion to molding, including conveyors.