Drives Motors Controls

Servosystem serves a need

Unimotor brushless AC servomotors meet the needs of the machine tool and automation industries for servosystems that provide high-speed positioning control.

These three-phase, six or eight pole, permanently excited synchronous motors exhibit a sinusoidal back EMF characteristic, providing high output torque with either high or low rotor inertia and with minimal cogging.

A finned motor housing increases the motor’s natural convection and improves thermal performance over naturally ventilated motors that have cylindrical or square frames with smooth surfaces. Single piece integral construction also improves performance.

Incremental encoders provide commutation and position feedback with other feedback options. Planetary gearboxes matched to the motor increase torsional stiffness, giving stable control of highly dynamic loads.


Machine tools, robotics and other demanding point-to-point applications are identified for the 400V class multi-axis servo drives said to be exceptionally compact, powerful and simple to install.

Yaskawa SGDC drives save up to 70% of the panel space taken by stand-alone units.

The flat packages are just 50mm wide. The drives have been optimised to get the best accuracy, speed and performance from Yaskawa’s servomotors delivering outputs of 0.5kW to 3kW.

Feedback is from high resolution incremental or absolute encoders.


The Indramat division of Mannesmann Rexroth has developed a new generation of high-voltage digital intelligent drives for pick and place and other production automation duties.

DIAX04 drive systems are based on a choice of modular power supply units with or without power regeneration and compact control units. Up to 35kW output is available to suit the power requirement and number of axes.

Synchronous and asynchronous motors cover linear, rotary movements and main spindle applications.


To prove its new Powermax II stepper motor works in hydraulic oil and other challenging conditions, Intelligent Motion Control immersed one in a jar of the fluid and ran it continuously in a year-long trial. There were no functional problems or deterioration of materials, the company says.

There are 87 Powermax models covering holding torques in the range 0.25Nm to 20Nm.