A Performance Comparison of Stationary Frame Control of Three-Leg and Four-Leg Voltage Source Inverters in Power System Applications

This paper presents a control performance comparison by simulation of a three and four-leg voltage source inverters for autonomous and grid connected operation under balanced and unbalanced loads; and asymmetrical voltage references. The voltage source inverters are described in the stationary frames αβ and αβγ in order to perform the system control action by employing a proportional resonant current compensator. Results are obtained by simulations in PLECS, which demonstrate that the three and four leg converters can achieve similar results under balanced and unbalanced loads. Besides, the four-leg inverter is able to control asymmetrical current and voltage references.