Sensorless AC drive control with LC filter

The paper presents the speed sensorless control of the induction motor in the system with the voltage inverter and LC filter. The LC filter is used to smooth the motor currents and voltages. In the control system the non-linear control method is used. For the state variables estimation the disturbance observer is implemented. Because of the voltage drop and phase shift caused by the LC filter the observer and the control system were modified. In the control system a multi-loop feedback controller was used. The modified state variables observer was developed taking into account the LC filter model. With the presented drive the speed sensors is not required. All the controls are based on measurement of the inverter output currents and dc input voltage. The proposed speed sensorless drive with the asynchronous motor was verified by the simulation and the experimental tests.