近年中壓固態變壓器於智慧微電網、再生能源、牽引系統等中壓系統中扮演重要角色，相較於傳統50/60 Hz之變壓器，高操作頻率可大幅縮小磁性元件體積和重量。本論文使用三階半橋架構使半導體元件只需承受一半輸入電壓，因此轉換器可承受較大的輸入電壓，此外CLLC諧振電路實現開關軟切換以降低整體損失提升功率表現與能量雙向傳遞，再者高壓側的絕緣系統設計以保護整體電路與驅動電路於電路崩壞時損毀。
本文研製一雙向諧振轉換器之雛型電路，其高壓側額定電壓5.2 kV、低壓側電壓400 V及額定功率40 kW，並使用模鑄式變壓器作為隔離變壓器，最後，以實驗高壓側2.6 kV，低壓側200 V驗證並佐證理論公式與SIMPLIS模擬的結果。

The medium-voltage solid-state transformers (SST) have played an important role in medium-voltage systems such as smart microgrids, renewable energy systems, traction systems and so on. Compared with traditional 50/60 Hz transformers, high operating frequency can greatly reduce the volume and weight of magnetic components. In this thesis, the three-level half bridge topology lets the voltages across the semiconductor elements are half of input voltage, therefore, the converter can withstand higher input voltage. The CLLC resonant structure realizes soft switching that reduce the switching loss to higher the converter′s efficiency and bidirectional power transfer. In addition, the insulation system is designed to protect the converter and driving circuit from damaged when the circuit breaks down.
A prototype circuit is made in this thesis. The high voltage side is 5.2 kV, the low voltage side is 400 V and the rated power is 40 kW. The cast resin transformer is used as isolation transformer in the circuit. Finally, the experimental high-voltage side 2.6 kV and the low-voltage side 200 V are used to verify and support the theoretical formula and the SIMPLIS simulation results.

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