No abstract

This study presents a non-isolated step-up inverter without leakage current for low-voltage renewable energy generation such as photovoltaic (PV) cells grid connection. From the structure of the proposed inverter, the negative terminal of the PV array is directly linked with the grid neutral, so the common mode voltage of the parasitic capacitance can be kept constant and the leakage current will not be generated in theory. Moreover, this transformerless inverter can produce an AC output voltage higher than the input DC voltage, which will reduce the sizes of the generation system. A switching modulation strategy carrier-based is analysed in detail when the input inductor current is operated in discontinuous conduction mode. The operation modes of the proposed inverter are also discussed, respectively, in positive and negative half line cycles. Finally, a digital experimental prototype is tested in the laboratory, and the experimental results are consistent with the theoretical analysis.

A novel DC-DC converter topology that uses a three-winding coupled inductor (TWCI) and a new voltagemultiplication technique is presented for achieving high voltage gain. The proposed converter comprises one boost unit, one passive absorption circuit, and two voltage-multiplier cells. The tertiary winding of the coupled inductor is connected to a capacitor and diode, and this combination acts as a secondary voltage-multiplier cell (SVMC). The SVMC, when combined with two capacitors, the secondary winding of the coupled inductor, a diode, and a switch, forms a primary voltage-multiplier cell, which can achieve a large voltage-conversion ratio that can be adjusted easily. The new voltage-multiplier technique can be used to decrease the number of capacitors and diodes, which improves the transformation efficiency. A prototype circuit with a nominal rating of 300 W is designed to verify the correctness of theoretical analysis.