A New Multilevel Conversion Structure for Grid-Connected PV Applications

A novel five-level optimized carrier multilevel PWM quad-inverter six-phase AC drive

“…Furthermore, it is confirmed by the fundamental components of VSIs that they are equal in amplitude and shown balanced operation as expected. Hence, it is proved that each VSI are capable of generating optimal five-level outputs by the developed single carrier zero-shifted five-level modulation (SCZSFM) algorithm and overcomes the drawback set by previously addressed dual inverter configurations [14][15][16][17][22][23][24][25][26][27][28][29][30][31][32]. …”

“…In such cases, the conventional three-phase dual inverters are the good solution. The two three-phase VSIs (two-level) are connected each at the open-ends of windings [14][15][16][17][31][32][33]. Moreover, the potential difference between two single inverter's leg potential constitutes the output voltages.…”

“…Output qualities are assured in additional by common-mode currents cancellation are carried out by the PWM techniques or by deliberately kept isolated dc sources [13][14][15][16][17][31][32][33]. Dual inverter with z-source impedance network in the dc link side configured and addressed for buck/boost the output voltages [31] with limited common-mode components and for grid integration with/without isolation transformer [32]. In this case again the dual inverters restricted with output levels, each leg pairs of phases by two VSI limit to three-level, and practically not possible to overcome.…”

A novel multilevel quad-inverter configuration for quasi six-phase open-winding converter

“…Generally, such topology is three-phase dual inverters, the three-phase VSI (two-level) are connected at the open-ends of windings [25][26][27][28][29]. The difference of two single inverter's leg potential constitutes the output voltages.…”

“…Benefits include half the switching frequency and DC bus requirements, moreover, two different potential sources can be utilized (photovoltaic/fuel-cell). Further, compromise the benefit with standard MLIs and cancellation of common-mode currents are carried out by the PWM techniques or by keeping isolated DC sources [25][26][27]. Recently, such configurations have been addressed for z-source impedance network in the DC link for a buck/boost the output voltages with limited common-mode components and standard dual inverters for grid integration with/without isolation transformer [25][26][27].…”