Sensorless control of stepper motors, in which the speed of the rotor is determined through a virtual encoder within the controller, is possible, claims German firm Nanotec.
“This enables the stepper motor to be operated as a servo-motor, with no step loss, no resonance and no risk of overheating,” said the firm. “It is now possible to exploit the advantages of closed-loop mode in applications in which the classic closed loop with encoder cannot be used due to cost constraints.”
An auto-set-up routine measures the connected motor and determines the required parameters.
Depending on the motor type, speed and positioning information is obtained at between 25 and 250rpm, with an accuracy comparable to that of an optical encoder with 500 or 1000 increments said Nanotec, allowing “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”.
Open-loop mode is also available for lower speeds and for positioning.
Sensorless control is available as a firmware update for all Nanotec N and C series controllers.
Nanotec is exhibiting at SPS IPC Drives 2014 in Nuremberg.
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