ClosedLoop

Closed control loop

In contrast to conventional stepper motor positioning controls where only the motor is actuated or the position adjusted via the encoder, sinusoidal commutation controls the stator magnetic field via the rotary encoder as in a servomotor. In this operating mode, the stepper motor acts as nothing more than a high pole servomotor, i.e. the classic stepper motor noises and resonances vanish. Because the current is controlled, the motor can also no longer lose any steps up to its maximum torque.

If the drive recognizes that the rotor is falling behind the stator field due to overload, adjustments are made with optimum field angle and increased current. In the opposite case, i.e. if the rotor is running in advance due to the torque, the current is automatically reduced so that current consumption and heat development in the motor and drive are much lower compared to normal controlled operation.

You can also compare the running behavior of the motor in the film with an open-loop controller: