以DSP為控制架構之主動箝位順向式轉換器之研製

Study and Implementation of a DSP Based Active-Clamped Forward Converter

許文欣(Wen-Hsin Hsu)

指導教授 ： 郭松村

崑山科技大學/工程學院/電機工程研究所/碩士(2008年)

摘要

在科技進步的現今，數位控制器逐漸地應用在特殊的複雜系統，而電力電子系統亦包括在其中。因此，本文將研製主動箝位順向式轉換器，並以DSP作為數位控制架構設計之研究。
主動箝位順向式轉換器能夠免除重置繞組與傳統順向式轉換器所使用的被動式箝位電路。而箝位電路的作用，即是當功率開關在截止期間，儲存其漏電感上之能量以抑制突波電壓，亦可使主開關在導通之時達到零電壓切換，以降低開關之切換應力。此外，利用同步整流在低電壓與高負載的條件下，也能夠有降低導通損失的效果。
狀態空間平均法可用以求得轉換器之狀態方程式。將控制迴路經過分析後，並利用MATLAB以數位重新設計法實現數位控制器之設計。本文以德州儀器(TI)所開發之數位訊號處理器TMS320LF2407A作為數位控制器的設計工具。而開迴路及閉迴路系統之波德圖，則用以分析系統的穩定度。
將電路經過分析後，以IsSpice軟體來模擬及驗證本文轉換器之動態結果。於研究室研製了標準規格為輸入電壓48V(範圍由36V~72V)及輸出功率30W之DC/DC轉換器。由實驗結果證明，本文所設計之數位控制器，符合了設計要求的暫態響應，在輸入電壓與負載的變動下，仍能適當的調整輸出電壓在穩定的範圍之內。

關鍵字

順向式轉換器 ； 主動箝位 ； 同步整流 ； 數位控制

並列摘要

With the advance in technology, digital controllers are increasingly being used especia1ly in complex systems, including power electronics systems. Therefore, this paper presents a DSP based digital control design and implementation of an active- clamped forward converter with synchronous rectifier.
The active-clamped forward converter can eliminate the reset winding or passive clamp circuit used in conventional forward converter. With the help of clamp circuit, the leakage inductor energy is retrieved therefore the spike voltage is avoided during turn-off, the clamp circuit also offers a ZVS for the turn-on of the main switch to reduce the switching stressed. Furthermore, the synchronous rectification (SR) is used to reduce conduction losses for the low-voltage heavy-load conditions.
A state-space averaging technique is used to drive the state equation of the converter. The control loop is then analyzed and the digital controllers are designed using MATLAB based digital redesign approach according to the specifications. Texas Instrument TMS320LF2407A chip is selected to implement the digital controller algorithms. The Bode diagram of the open-loop and closed-loop system is given to analyze the system stability.
After the circuit analysis, the dynamic performance of the proposed converter is simulated by IsSpice. The prototypes of a DC/DC converter with an input of 48 V (ranged from 36~72 V) and output of 30 W have been implemented in the laboratory. The experiment results show that the designed digital controller can meet the desired transient response, and the output voltage is well regulated under input voltage and load variations.

並列關鍵字

forward converter ； active-clamped ； synchronous rectifier ； digital control

參考文獻

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