Nonlinear control technique for three-phase boost AC/DC power converter

This paper presents a novel nonlinear control method for a three phase boost AC to DC switched mode rectifier (SMR). A cascade type control structure is proposed, because the dynamics of the current loop are much faster than the dynamics of the DC voltage loop. This can be justified by the singular perturbation theory. The fast nonlinear current controller in inner loop and slow DC voltage PI controller in outer loop are analyzed. System model equations stability analysis is performed at (d,q) rotating reference frame. Performance requirements as: (1) sinusoidal input currents waveform, (2) power factor correction, and (3) robust control of unknown and varying load are well satisfied. The PWM that is also proposed has the following advantages: (1) dynamic performance is under continuous control, and (2) switching frequency can be selected and be fixed. In addition the overall control method has the advantages: (1) there is no need to measure the input voltage magnitude and frequency, and (2) the power factor correction method is not based on input voltage multiplication, but uses the input currents phase angle as distinct control parameter. The principles of operation of the proposed control scheme are explained. Simulation and experimental results are presented to verify the feasibility of the control strategy.