Abstract:

A new type of converter topology is proposed in order to solve the problem of the low output voltage of photovoltaic power generation by introducing a type of coupled inductor voltage doubler unit. The working principle of the converter is analyzed, and the expressions of voltage gain, voltage stress and critical equivalent inductance time constant are given. By comparing the traditional Sepic converter and other Sepic converters, the proposed converter increases the voltage gain by nearly 7 times. At the same time, the voltage stress of the switch tube is lower. And using the method of decoupling magnetic integration, inspired by the traditional EE-type magnetic core, a new type of 4-U-type magnetic core structure is proposed. The magnetic flux density distribution of the magnetic core is more uniform and it makes the integrated magnetic parts after magnetic integration smaller. The smaller volume is also conducive to heat dissipation. The experimental prototype test shows that the efficiency of the converter reaches 93.9%, and the measured experimental waveform conforms to the theoretical analysis.

Key words: Sepic converter, coupled inductor, high gain, low stress, decoupling magnetic integration