Research On Dual Switches DC/DC Converters With High Step-up Voltage Gain

Take the reliability and security into consideration, connecting a single fuel cell stack or PVmodule to the grid is one of the research foucs. Unfortunately, the output voltage of these sources isrelatively low; it should be boosted to a high voltage to feed the AC grid or UPS. High step-up, highefficiency DC/DC power conversion has became one of the key technologies in these fields.The efficiency of transformerless DC/DC converter could be higher by remove the DC/AC/DCpower conversion, which are usually the variations of Boost converter. Compare to the Boost, dualswitches converter can reduce the voltage and current stress, the variations of dual switches convertercan achieve high efficiency by inheriting the advantages, which have a broad prospect.Firstly, this paper illustrates the principle of dual switches converter in ideal situation, then theprinciple of the converter in actual situation is discussed; passive clamping is adopted to balance thevoltage across the switches, which reduce the stress and raise the efficiency. The characteristics of theproposed converter are discussed and some comparisons are made to illustrate the advantages.Secondly, this paper combines switched cells like switched inductors (SL) and switchedcapacitors (SC), proposes several switched cell dual switches converters, proposes a multi-cell SL-SCdual switches converter, then the proposed SL dual switches converter is improved by replacing theSL to tapped inductor. According to the proposed converters, several phototypes are established andthe experiments are conducted.Thirdly, this paper combines coupled inductor, proposes three-winding-coupled inductor dualswitches converter. Then active clamp circuit is adopted to realize ZVS which raises the efficiency.The operation principle and the characteristics of the converters are discussed, the phototypes areestablished to conducte the experiments.Finally, a methord is proposed to transfered the two classes of coupled inductor converters and amethord to deduct these converters is illustrated, experiments are conducted to prove the analysis.All the proposed novel converters not only extend the voltage conversion ratio to prevent a largeduty cycle, but also reduce the voltage stress, which decreas the loss and raise the efficiency. The dualswitches Boost converters have a great value of theory and application.