This paper presents a new three-phase dc-ac inverter based on the basic Cuk converter. The main feature of the proposed topology is the fact that the energy storage elements as inductors and capacitors values can be reduced in order to improve the reliability, reduce the size, and the total cost. Moreover, the bucking-boosting inherent nature of the Cuk converter, depending on the time-varying duty ratios, provides more flexibility for stand-alone and grid connected applications when the required output AC voltage is lower or greater than the DC side voltage. This property is not found in the conventional current source inverter (CSI) when the DC input current is always greater than the ac output one or in the conventional voltage source inverter (VSI) as the output ac voltage is always lower than the dc input one. Averaged large and small signal models are used to study the Cuk nonlinear operation. Basic structure, control design, and MATLAB/SIMULINK results are presented in this paper. The new three-phase DC-AC inverter is very convenient for PV applications where continuous average input currents are required for appropriate Maximum power Point Tracking (MPPT) operations.
- voltage control
- power generation reliability