A novel phase shift full bridge (PSFB) converter with voltage-doubler and decoupling integrated magnetics in photovoltaic (PV) systems is proposed. Considering the demand that the output voltage is higher than the input voltage in PV systems, the voltage-doubler is added to achieve higher voltage gain compared with the traditional PSFB. In order to avoid current oscillation caused by the voltage-doubler and obtain the wide zero voltage switching (ZVS) ranges, an external inductor is imposed on the circuit. Especially, to obtain much higher power density, the external inductor and transformer are integrated into one magnetic core. The operation and voltage gain of proposed converter are analyzed. Also, in order to reveal the effects the integrated magnetics gives to the converter, the decoupling condition and the expression of leakage inductor of integrated magnetics are obtained in detail. Finally a 100 W prototype converter is made and the experimental results are given to verify the analysis.
Trace elements Co, Cr were added to investigate their influence on the microstructure and physical properties of Al-Si extruded alloy. The Co, Cr elements were randomly distributed in the matrix, forms intermetallic phase and their existence were confirmed by XRD, EDS and SEM analysis. With addition of trace elements, the microstructure was modified, Si particle size was reduced and the growth rate of β-(Al5FeSi) phase limited. Compared to parent alloy, hardness and tensile strength were enhanced while the linear coefficient of thermal expansion (CTE) was significantly reduced by 42.4% and 16.05% with Co and Cr addition respectively. It is considered that the low CTE occurs with addition of Co was due to the formation of intermetallic compound having low coefficient of thermal expansion. The results suggested that Co acts as an effective element in improving the mechanical properties of Al-Si alloy.