Disturbance Observer-Based Feedback Linearization Control for Stand-Alone Inverters

This paper presents a disturbance observer-based control (DOBC) for stand-alone inverters to produce sinusoidal voltages. The controller is specifically designed to regulate the output voltage of the inverter to follow a desired sinusoidal voltage reference. The disturbance observer is employed to ensure accurate tracking of the voltage reference by compensating for model uncertainties and unknown inputs. The combination of a linearizing feedback control (LFC) with a disturbance observer (DO) makes it possible to perform dual functions by providing improved disturbance rejection during transients and attaining zero steady-state error thanks to the integral action property of the disturbance observer. The key feature of the proposed controller is that it is designed in the dq reference frame, but it is implemented in stationary αβ coordinates. The performance of the above controller during load variations is verified via simulation tests. The test results have demonstrated excellent disturbance attenuation to achieve good transient response during balanced and unbalanced load variations.