At this year's SPS IPC Drives show, Nanotec, based in Feldkirchen near Munich, will be the first manufacturer in the world to launch a sensorless control for stepper motors in which the speed of the rotor is determined by means of a "virtual encoder" within the controller. This enables the stepper motor to be operated as a servo motor – with no step loss, no resonance and no risk of overheating.
In Nanotec's sensorless system, an auto setup routine measures the connected motor and automatically determines all the required parameters. Depending on the motor type, speed and positioning information is obtained at a lower speed of between 25 and 250 rpm with an accuracy comparable to that of an optical encoder with 500 or 1000 increments, so that a level of control can be achieved of the same quality and with the same torque as a motor controlled by means of an encoder. It is possible to switch automatically to open loop mode for lower speeds and for positioning purposes.
This technology means that it is now also possible to exploit the advantages of closed loop mode in applications in which the classic closed loop with rotary encoder cannot be used due to cost constraints. The new sensorless control is available as a firmware update for all N and C series controllers from Nanotec.