A current control system based in /spl alpha//spl beta/0 variables for a four-leg PWM voltage converter

A four-leg PWM voltage power converter is presented in this paper for three-phase four-wire active power filters or neutral current compensator applications. The four-leg PWM voltage converter AC currents should be controlled. This is accomplished with a generalised space vector based current controller in an /spl alpha//spl beta/0 coordinate system. This controller enables to impose equal hysteresis errors in the converter four wire currents. All the current harmonic systems of positive, negative and zero sequence can be injected by the converter and thus compensated in the mains. This converter has superior performance compared with the four-wire three-phase PWM voltage converter with split DC-link capacitors.