Sensorless positioning with COMBIVERT S6

Sensorless positioning of drum motors with the KEB COMBIVERT S6 (n)one-cable-servo

Momentum Technologies GmbH in Hückelhoven-Baal – a partner company of the Rollex Group - is a young, dynamic technology company that focuses on the development, production and marketing of next-generation drum motor technology.
The emphasis is on producing robust, oil-free drum motors and powered rollers for the food industry, logistics and other sectors that are already achieving tomorrow's level of energy efficiency classes.
The special feature is sensorless positioning of the drum motor by Momentum Technologies GmbH in conjunction with the new KEB COMBIVERT S6 servo-controllers, which offer highly dynamic positioning without sensor signals. 

The optimum technique for this is based on the KEB ASCL (Asynchronous Sensorless Closed Loop) and SCL (Sensorless Closed Loop) control method. Speed-controlled applications of asynchronous and synchronous sensorless machines have been used successfully for over 15 years, especially in applications for finish-machining, plastics engineering and Recycling.

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The new KEB COMBIVERT S6 controllers herald a new era: high-performance current regulation and enhanced motor models now also enable positioning tasks to be handled dynamically for SCL-type motor operating modes. With HF-INJECTION, resolution in the speed range increases by less than 1 % of the rated motor speed, now affording maximum torque up to standstill. In addition to this, motion-free rotor commutation is possible with FIVE-STEP (for motors with Ld=Lq) or HF-DETECTION (for motors with Ld≠Lq).

Practical example of results:

In just a few minutes, all the relevant motor data are measured and the new operating mode activated intuitively, complying with CiA402. In current motor positioning of MTS 82 by Momentum Technologies, with sudden loading at the rated torque, positioning accuracy of 0.88° is achieved, after 100ms positioning accuracy falls to 0.07°.  This control accuracy makes sensorless positioning very interesting for most industrial applications.

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To sum up:

dynamic position-controlled operation of sensorless drum motors offers the advantage of substantial savings compared to conventional sensor-type solutions by dispensing with the entire sensor system with sensor cable and sensor interface. In addition to this costs for installation and wiring are also reduced. High interference resistance of the robust drive system and use of standard motor cables with lengths up to 100 m are further important criteria.

For 2018 KEB is planning the implementation of extended safety functions, such as SDI or SMS in applications for sensorless positioning.