共振式蓄電池充電器之研製

Design and Implementation of Resonant Converters for Battery Chargers

張永東(Yong-Dong Chang)

指導教授 ： 莊英俊

崑山科技大學/工程學院/電機工程研究所/碩士(2004年)

https://doi.org/10.6828/KSU.2004.00055

摘要

為了實現高性能、低切換損失、高效率與低成本之蓄電池充電器，本論文採用三種具有柔性切換特性的負載共振式直流轉換器，應用於電池，分別為(1)串聯負載共振式蓄電池充電器；(2)並聯負載共振式蓄電池充電器；(3)串並聯負載共振式蓄電池充電器。以負載共振式直流轉換器作為蓄電池充電器電路，具有電路結構簡單、元件數目少、體積小、重量輕、功率密度高、效率高及低成本等優點。
針對負載共振式轉換器所產生的交流電源，需於輸出端利用整流器，並依據電路特性設計低通濾波器以消除高頻漣波，再供給蓄電池穩定的直流電進行充電。電路的設計以脈波寬度調變的方式控制兩個主動開關，透過適當的參數設計使共振式轉換器操作於連續電流模式，並使主動開關能於零電壓切換導通或截止，以維持電路高效率。至於電路參數的設計是以共振槽的特性阻抗為基準，調變切換頻率並固定主動開關的責任週期，藉由頻率的變化改變電路阻抗，以控制充電電流的大小，透過頻率響應立體圖，挑選適當的操作點，使共振式充電器運作於最佳狀態，以獲得高效率。此外，本論文所設計之共振式充電器亦於蓄電池端裝置過電壓偵測電路，防止蓄電池過充，以延長蓄電池使用壽命。
本論文根據開關切換情況配合輸出濾波器電路結構，建立整體電路的工作模式，分析電路操作原理，撰寫電路各元件特性方式程式。為了簡化電路分析，應用基本波近似法與蓄電池的簡化等效電路，建立負載共振式蓄電池充電器的等效電路，並以此等效電路為基礎，推導電路參數的設計方式及設計流程。最後，以電腦模擬與實際電路作理論驗證。實驗的結果相當令人滿意，三種負載共振式蓄電池充電器的效率均高達80%以上。

關鍵字

充電器 ； 特性阻抗 ； 脈波寬度調變 ； 柔性切換 ； 共振式轉換器

並列摘要

In order to achieve the goal of a high performance, low switching loss, high efficiency, and low cost battery chargers, three different soft-switching load resonant DC-DC converter topologies are adopted for the design of battery chargers. They are: series-loaded resonant (SLR), parallel-loaded resonant (PLR), and series-parallel-loaded resonant (SPLR) battery chargers. To apply the load-resonant DC-DC converter technology on battery charger bears the advantages such as simpler circuit structures, less component count, smaller volume, lighter weight, higher power density and efficiency, as well as lower cost.
The ac output produced by the load resonant converter should be rectified into a dc current to charge the battery. In order to remove the high-frequency ripples and to have a steady dc charging current, the rectified dc current should be fed into a low-pass filter which is designed according to the features of the circuit. The two active switches of the load resonant converter are gated by pulse-width-modulation (PWM) controller. The converter is operated under continuous-conduction mode (CCM) by the appropriate parameter design, and the two power switches are turned on and off with the pleasing feature of zero voltage switch (ZVS). Therefore, high efficiency can be achieved. The circuit parameters are decided by choosing an adequate intrinsic impedance of the resonant circuit. As the duty ratios of the active switches are fixed, the charging current should be programmed via tuning the circuit operation frequency and therefore the circuit impedance. The optimum operating point is sieved by the frequency response diagram to operate the charger at high efficiency. In addition, a over-voltage detector is equipped in series with the battery to keep the battery from being over-charged and extend its cycle life.
According to the switching operation and the structure of the filter circuit, the operation modes and characteristic equations of the integrated circuit are established and analyzed. To simplify the circuit analysis, fundamental wave approximation and the simplified equivalent circuit of battery are applied to build the equivalent circuit of the load resonant battery charger. Based on this equivalent circuit, the circuit parameter design equation and design procedure are deduced. Through computer simulation and laboratory circuit experiments, satisfactory results are obtained. All the three load resonant battery chargers can reach an efficiency higher than 80%.

並列關鍵字

Pulse-Width- Modulation ； Resonant Converter ； Soft-Switching ； Charger ； Characteristic Impedance.

參考文獻

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