Closed-loop control structure for damping low-frequency vibrations

A closed-loop control structure for positioning a load with the aid of an electric motor, comprising:

• an arrangement adapted to actively damp unwanted, low-frequency vibrations;
• a position controller adapted to receive a deviation of an actual position of the load from a setpoint position and to output a setpoint speed;
• a speed controller adapted to receive a deviation of an actual speed of the load from the setpoint speed and to output a setpoint current;
• a current controller adapted to receive a deviation of an actual current of the motor from the setpoint current and to output a setpoint voltage for operating the motor;
• wherein damping signals adapted to counteract unwanted, low-frequency vibrations are injectable in the control loop;
• wherein a first damping signal and a second damping signal of different phase angle are derivable from a single sensor signal;
• wherein the first damping signal is injectable between the position controller and the speed controller;
• and
• wherein the second damping signal is injectable between the speed controller and the current controller.