| With the development and utilization of renewable energy, hybrid energy generationsystem has attracted increasingly more attention. Multi-input DC-DC converter caneffectively combine different types of input sources together, which has advantages ofhigh power density, low profile and simple control compared with traditional single-inputconverter, and herefore, is suitable for the hybrid energy generation system.However, the coupling relationship between multiple variables always exists in themulti-input converter control loops, increasing the difficulty of regulator design. In thisthesis, a new hardware-decoupling control method is proposed to solve this problem,which can be applied into various types of multi-input converters.The main contents ofthis thesis are as follows:This thesis analysed the current coupling between the different converter ports basedon the equivalent circuit model and mathematical model of an isolated three-port converter.Prior to proposing the hardware-decoupling method, the traditional decoupling methodand its shortcomings were pointed out. Multi-input converter topologies which can use thehardware-decoupling method were summarized as well.Fourier decomposition was applied on the voltage square-wave of the voltage-fedthree-port converter. The converter’s soft-switching condition was firstly analysed basedon the fundamental equivalent model and third harmonic equivalent model of thethree-port converter, and the relation between the soft-switching range and the leakageinductance was derived afterwards. On the basis of the above analysis, it was proposedthat soft-switching was realized by setting the leakage inductance at an appropriate value.Furthermore, the converter’s small-signal average model was deduced and the close-loopcontrol strategy was designed in this thesis, which was validated through softwaresimulation.A200W prototype was built in the laboratory. The experimental results verified thetheoretical analysis. |
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