مبدل DC–DC با مقدار کمیت الکتریکی بالای غیر ایزوله با پذیرش خازن کمکی و سلف تزویج شده Non-isolated high step-up DC–DC converter adopting auxiliary capacitor and coupled inductor

1 Introduction Since it takes centuries for the traditional fossil energy to be replenished, it will be exhausted with the growing demand for energy of human society. Thus the energy crisis is increasingly serious. Meanwhile, the excessive usage of the traditional fossil energy has polluted the environment and resulted in greenhouse effect on a global scale [1]. Therefore, it is becoming more and more important to optimize the energy consumption structure and to utilize clean and renewable energy. Solar energy and hydrogen energy are two promising renewable energy, and have extensive application prospect. As the utilization methods of the two new energy, photovoltaic (PV) and fuel cells power generations have been applied on a large scale [2–7], such as photovoltaic power station and electric vehicle. In recent years, the grid-connected power generation based on PV source for residential application has become globally popular. Usually, an interface unit is necessary, as the output voltage of PV source is relatively too low for the line voltage. If the line voltage is 220 V, the input voltage needed by the grid-connected inverter would approach 380 V. But the output voltage of PV source generally varies from 25 to 45 V. To boost the output voltage of PV source, one possible solution to is to make series-connected PV arrays. But the total output power of PV arrays will be degraded due to module mismatch or partial shading [8]. Another promising solution is to utilize a high step-up DC– DC converter to match the low output voltage of PV source and high input voltage of the inverter. Then every PV source can realize the function of maximum power point tracking. For the isolated DC–DC converters, the voltage gain can be increased by adjusting the turns ratio of the transformer. But the energy stored in the leakage inductor is difficult to be transferred to the output. Thus, for the application without galvanic isolation requirement, nonisolated high step-up DC–DC converters is preferred.