Improved High Step-Up Cockcroft-Walton Magnetic Coupling Inverter

An improved dual winding magnetically coupled-inductors inverter based on a Cockcroft-Walton multiplier voltage cell is proposed in this paper. Compared with the conventional generalized Cockcroft-Walton multiplier voltage Z-source inverters, the proposed inverter attains higher voltage gain by decreasing the transformer’s turns number. As a result, lower cost, higher efficiency, larger voltage boost factor, and higher density can be realized in the proposed inverter. Furthermore, unlike conventional magnetically coupled impedance source inverters, the proposed topology offers a larger voltage boost factor for small shoot-through duty ratios with a smoother slope, which enhances the practical controllability of the inverter. Hence, a higher modulation ratio can be applied, which results in a better quality of the inverter’s waveforms. A clamping circuit is used to reduce the leakage inductance effects of the coupled inductors. As a result, the huge voltage spikes across the inverter bridge are eliminated. In addition, the proposed inverter draws a smooth and continuous input current from the input dc source, which is suitable for renewable energy sources. Detailed, theoretical analysis, simulation and experimental results are provided.