Synchronous EMF torque motors: New alternative for elevators and more

20 years ago, engineer Michael Prokopp co-developed a type of new electric motor to outperform traditional motors. Now sold through startup EMF97 Gmbh, this synchronous torque motor reaches high torque at low speeds and is more efficient than many traditional motors.

Shown here are EMF motors from EMF97 Gmbh.

While leading manufacturers in this industry get 76% efficiency from comparable motors, the EMF motor is 94% efficient — a leap in motor efficiency. Plus the motor price is half that of comparable motors … so that EMF97 now aims to replace conventional electric motors and mechanical gearboxes. “Traditional systems are noisy, consume oil; are subject to wear, and must be constantly maintained,”  said Prokopp.

The EMF motor principle was patented in 1997. Though at first industry responded with skepticism, a Turkish investor Hasan Kayakiran noticed the new technology at the 2002 Hannover Fair. Soon after that, Prokopp and co-inventor Jurgen Lindner founded EMF97 GmbH … and in cooperation with Kayakiran, established a production facility in Istanbul (even with development still in Worms, Germany). Now 15 years and some 10,000 motors later, EMF motors are used in many applications, with the most common use in elevators and extrusion machines.

In November 2016, EMF97 filed a new patent for a motor targeted towards the wind-power industry. In March 2017, EMF was honored in Istanbul with a German-Turkish Innovation Award. According to company sources, EMF97 sales also doubled last year.

Basics of how EMF motors work

The wound stator of the EMF motor is almost the same as a traditional motor. Magnets are glued to the rotor. Input voltage and a frequency spur a magnetic flux … so as frequency increases, the electric field in the wound stator begins to turn. The rotor moves in a direction opposite the rotating field — and more slowly. The number of magnets and the geometry of the motor defines the speed ratio. The motor outputs very high torque with a low number of winding poles; low copper and hysteresis losses keep efficiency high.

The high number of magnetic poles impart smooth ripple-free rotation and dynamic performance. Plus these motors need no additional cooling, so there’s no other motor design with comparable efficiency or such a high torque-to-weight ratio.