Nonlinear virtual flux oriented control for sensorless active filters

This paper presents the development of a control strategy for active filters, without measuring of grid voltages and load currents. The strategy uses the virtual flux to obtain the grid synchronization angle. The input currents are transformed and controlled in the synchronous coordinate system, allowing operation with high power factor. The converter model is nonlinear and multivariable, thus, the technique of feedback linearization to design compensators is used. Experimental results obtained in the laboratory from a prototype converter are presented in order to validate the proposed control, covering the analysis of stationary and transient responses.