The LLCLC resonant converter based pseudo DC link inverter

Abstract

Technological advancements in solar power systems necessitate highly reliable power inverters with a high efficiency and a small size. An LLC resonant converter-based pseudo Direct Current (DC) link inverters offer these qualities to some extent. The resonant circuits of conventional pseudo DC link inverters lack the ability to attain a zero gain and cannot handle variable frequency control which in turn requires very large filters to produce pure sinusoidal output voltages for grid. The usage of these filters consequences in the enhanced price and size of inverters; moreover, the reliability of inverters is also reduced. We propose a novel topology for a pseudo DC link inverter based on an LLCLC resonant converter. The proposed inverter does not require large filters, because it generates rectified sinusoidal output voltages. An additional parallel LC component is added in series to the resonant circuit, which makes it able to attain a zero gain through an infinite circuit impedance. The 400 W pseudo DC link inverter with a 40 V input and a 400 V output is designed and simulated on OrCAD PSpice software. The results showed that there is a significant improvement in achieving a zero gain. The possible lowest gain achieved is approximately 0.125. The proposed technique attested to be more efficient than those formerly used, subsequently contributing satisfying outcomes.