# Influence of MOSFET Parasitic Capacitance on the Operation of Interleaved ZVS Boost Converters
## 1 Introduction  
Renewable energy sources' share in the world's energy production has been steadily rising in recent years, up to 5% in 2019, excluding hydroelectric energy [1]. Renewable energy sources, especially photovoltaic plants, often require DC/DC boost converters to increase the level of DC voltage before it may be supplied to a grid connected converter (GCC). Many converter topologies were analyzed and developed over the years with these applications in mind. Such converters are typically developed in buck-boost [2; 3; 4; 5] or boost [6; 7; 8; 9; 10] topologies. A common trend is to maximize the power density of power electronic converters. In order to achieve high levels of volumetric power density switching frequency is increased as that allows the use of smaller passive components. However, increasing the switching frequency causes switching losses to increase as well. These losses may be significantly reduced by using soft switching techniques, either resonant and quasi-resonant topologies or creating zero-voltage or zero-current switching conditions (ZVS and ZCS) by using auxiliary switches [11; 12; 13; 14]. However, novel soft switching topologies are usually complicated and use many semiconductor devices. A simple multi-phase soft switching boost converter topology is the one described in [15]. Since its first description it has not been developed, despite its potential applications in high power density systems, as well as conventional renewable energy generation installations and as a boost stage in any device that requires it. Its analysis in [15] lacks generalization for any number of phases, as it has onlybeen described in two-phase variation. Additionally no description of the influence of transistor parasitic capacitance is provided. Furthermore applying the considered topology in a renewable energy generation system or any other power supply system requires a control method to be developed in order to regulate the output voltage. The research described in this paper aims to fill these gaps by providing an analysis of the converter voltage ratio for any number of interleaved phases, using the obtained equations to compare the experimental and analytical results and proposing a control method for regulation of the output voltage of the converter. The paper is divided into eight sections. Section 1 is an introduction that provides an overview of the converter topology and main waveforms of currents and voltages. Section 2 deals with the analysis of the converter voltage ratio. Along with Appendix A this section shows the derivation of an implicit function that connects the voltage ratio with the switching frequency and load resistance. In Section 3 the aforementioned analysis is used to derive conditions for soft switching and it is shown how the circuit parameters affect the converter operation. Section 4 presents the load characteristics and shows how crucial the load resistance and characteristic impedance of the resonant circuit are in the design process of the converter. Section 5 presents an experimental prototype that was tested and compared to the analysis results, possible explanations for differences are also provided. In Section 6 the possibility of output capacitance influencing the experimental results is investigated and the analysis is performed again with parasitic capacitance taken into account. Another comparison between experiments and analysis is provided. Section 7 presents a proposal of a control method for the analyzed converter. The method is later modelled in simulation software and the model is simulated to confirm the feasibility of the voltage regulation system. Conclusions are then provided in Section 8.