Quasi-Z-Source three-phase rectifier modelling and control

Abstract

AC to DC rectifiers are used as front-end interface in multiple applications with DC load or in inverter fed from line voltage. In applications with variable AC input voltage, rectifiers with buck-boost capability are critical for achieving the most efficient power conversion. The Z-source rectifier has been presented as the most suitable rectifier with buck-boost performance. This dissertation introduces and analyses the quasi-Z-source rectifier as an alternative efficient AC to DC converter with buck-boost capability. The model of the quasi-Z-source rectifier is derived. The model of the Z-source rectifier is also derived with an alternative approach. It is found from analytical results of the modelling that the quasi-Zsource is a more cost-effective rectifier than the Z-source rectifier due to lower rated capacitors. A two stages closed-loop controller for the quasi-Z-source rectifier is then designed. Software simulations and hardware experiments of the quasi-Z-source rectifier are performed and the results obtained confirm its efficient performances. This makes the quasi- Z-source rectifier appropriate in renewable energy systems with AC voltage variations such as wind power.