Extended control strategy for a PWM line-friendly AC-to-DC converter

A three-phase DC-link, IGBT, PWM converter was studied. The applied control strategies used all the allowed switching operations of the semiconductor devices such that the converter has a line-friendly performance. High dynamic and satisfactorily steady-state performances of the converter were obtained. Simulated results and careful experiments indicate a relatively significant DC-voltage drop at the output of the converter when the load changes. In order to minimize this important modification of the DC-voltage level, more complex control strategies were studied. The desired line-friendly operation mode is kept active only for the load values that are less than the prescribed one. If an overload appears, in motoring or generating operation mode, nonactive power is generated, so that the DC-link voltage is kept constant. The author deals with these control strategies and analyses the converter performances