PWM inverter harmonic correction topologies for three-phase diode rectifiers

The functional operation of a range of harmonic correction topologies are described that draw sinusoidal AC supply currents using filter inductor sizes typically in the range 0.02 to 0.06 pu. The PWM inverter cell used in each of the various topologies can be operated with current ratings around 0.3 to 0.5 pu as compared with 1 pu for a standard PWM rectifier. The various topologies described have a range of potential advantages, such as: (a) low per-unit current ratings, (b) low dv/dt stresses between the rectifier DC link and the AC supply, (c) control of the rectifier output voltage and rectifier DC-link currents, (d) can be placed on top of a standard diode rectifier configuration, (e) balanced supply currents when the supply voltage is unbalanced, (f) bidirectional power flow, and (g) functionally equivalent structures using either AC or DC diode rectifier inductors. The features of the various topologies are illustrated using both circuit waveforms and performance curves