本論文提出並探討疊接架構於燃料電池的應用，燃料電池(Fuel cells)是相當有潛力之再生能源，利用疊接轉換器之電壓補償和分配的特性提升燃料電池電力系統之效能。疊接式電源轉換器僅透過一隔離式電力轉換器處理少部份能量，大部份能量直接傳送至輸出負載，以電壓補償之概念來提升系統之效率。在燃料電池的應用中，可利用疊接之特性來補償燃料電池的極化損失，藉此調整燃料電池系統輸出電壓。另外，本文提出各種不同型式之疊接轉換器，並以順向疊接轉換器(Cascoded forward converter)為例，推導並設計其電壓增益、效率、小訊號模型、及電路參數。
利用疊接特性，提出一高效率雙向疊接式電力轉換器。結合燃料電池(Fuel cell)、鉛酸電池(Battery)、超電容模組(Ultra capacitor module)，完成一混合電源系統並以模擬車輛運行方式討論電力潮流控制。另外，提出一主動式燃料電池電壓控制策略，以數位單晶片(DSP TMS320F2407A) 為控制核心，藉以管理疊接式混合電源轉換器之間的電力潮流。文中將推導轉換器之六方向效率及電壓增益比，並以模擬及實測結果來驗證混合電源系統之電力潮流和效率，本文提出之疊接式混合電源轉換器之整體效率可高達96%。為了高電壓之應用，延伸此高效率之雙向疊接式電力轉換器，以多層電源疊接之概念，提出疊接式三電源混合供電系統。另外，提出雙回路主動燃料電池電壓控制策略，來控制此三電源疊接系統，以達到高效率的電能管理。
為了彈性連接轉換器以達到高電壓的應用需求，本文將延伸電源疊接結構至多模組疊接結構。提出自動主控式回路調整(Automatic-master loop regulation)控制並結合省電模式(Green-mode)控制，針對不同容量之電力轉換器，以電壓分配的方式管理各個疊接模組之間的功率。最後，利用多台不同額定功率的順向式轉換器進行疊接，結合提出的控制方法，以實測結果來驗證理論分析。
基於疊接概念，已提出雙向疊接式電力轉換器及多層疊接式轉換器，應用於燃料電池混合供電系統中。更針對多模組疊接系統，探討不同額定功率模組之電壓分配及改善系統之輕載轉換效率。而各類疊接式轉換器之理論推導及實測結果，已於本論文中被驗證和實現。

This dissertation presents and studies the cascoded converter configuration for fuel cell (FC) applications. Using the concepts of voltage compensation and voltage allocation, the performance and efficiency of an FC conversion system can be improved. The source cascode converter provides power, which is divided into two parts; a fraction of the power is passed through a converter resulting in conversion loss, whereas the other part is supplied directly to the output load without any power loss. Therefore, the source cascoded topology uses the concept of voltage compensation to achieve high efficiency. Using the cascoded topology in an FC-supplied system, the cascoded characteristics can be utilized to compensate the polarization loss of FC for regulating the output voltage. A number of cascoded circuits are also proposed in this dissertation. Based on an example of a cascoded forward converter, the voltage gain ratio, efficiency, small signal model, and circuit parameters are derived and designed for FC application.
Utilizing a cascoded bidirectional configuration, a hybrid power system combining FC, battery, and ultra capacitor modules (UCM) is proposed for vehicle applications. An active FC voltage control strategy is presented to manage the power flows of the proposed hybrid system through a control chip (DSP TMS320F2407A). Six-direction voltage gains and efficiencies of the proposed hybrid system are derived in this dissertation. The simulation and experimentation results are used to verify the efficiency and power flows of the proposed hybrid system. The overall efficiency of the proposed hybrid power system can achieve 96%. For high-voltage applications, a three-source cascoded system is presented by extending the high-efficiency cascoded bidirectional configuration and using the multi-source cascoded concept in this dissertation. Moreover, a two-loop active FC voltage control for the proposed system is presented to achieve highly efficient power management.
To address flexible connections for high-voltage applications, the source cascoded topology is extended to a multi-cascoded topology. A novel automatic master loop regulation (AMLR) control scheme and the green-mode control scheme are combined to control multi-module cascoded converters at different power ratings, where the output voltage of the individual converter can be allocated to achieve optimum power management. Finally, the experimental prototypes of a forward multi-cascode system at different power ratings combined with the AMLR and green-mode control scheme are used to verify the voltage-allocation ability.
Based on the cascode concepts, the bidirectional cascoded converter and multi-source cascoded system have been designed and implemented for the FC hybrid power system. In addition, in multi-module cascoded system, the voltage allocation is implemented and light-load efficiency is improved. These theoretical analysis and experimental results of each cascoded configuration have been verified and implemented in this dissertation.

A.Fuel Cell Application
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C. Modeling for PWM Converter
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D. Hybrid Power System
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E. Multi-Output Cascoded Converter
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