並聯負載共振式太陽能蓄電池充電器

Battery Charger with Parallel-Loaded Resonant Converter for Photovoltaic Arrays

楊嘉瑋(Jia-Wei Yang)

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(2005年)

https://doi.org/10.6828/KSU.2005.00053

摘要

由於環保意識抬頭與石油價格飆漲等問題再度顯現，尋求新式的替代能源成為世界各國所共同努力的目標。太陽能具有取之不盡、用之不竭且無污染的特性，因而成為主要的研究議題之一。尤其地處亞熱帶的台灣，擁有充份的陽光，日照量充足，日照時間又長，對於太陽能發電最具有開發的潛力。為了儲存太陽能光電板所產生的電力，必需設計一高性能、低切換損失、高效率與低成本的蓄電池充電器，本論文採用具有柔性切換特性的並聯負載共振式直流轉換器，應用於蓄電池充電器。此種並聯負載共振式太陽能蓄電池充電器電路，具有電路結構簡單、元件數目少、體積小、重量輕、必v密度高、效率高及低成本等優點。
針對並聯負載共振式轉換器所產生的高頻交流電源，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並聯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與零電流切換導通，以維持電路的高效率。至於並聯負載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，本論文所設計的並聯負載共振式太陽能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，建立並聯負載共振式太陽能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，此種新型的並聯負載共振式太陽能蓄電池充電器的充電效率高達80%以上。

關鍵字

共振式轉換器 ； 柔性切換 ； 充電器 ； 特性阻抗 ； 太陽能

並列摘要

Because of the issue of environmental protection resumes and the price of petroleum rises crazily , the attempt to seek for alternative energy source is a goal that would take universal efforts throughout the world. Among them, the solar energy is abundant, continuous supplying and pollution-free, hence, gathers many attentions on its research. As for Taiwan, located in subtropical area, there is sufficient sunshine; lots of sunlight and long sunny days, solar energy should be the most prominent candidate for green energy. In order to reserve the electrical power transformed from solar energy, a battery charger with high performance, low switching losses, low cost and high efficiency should be designed. This paper proposes a battery charger with soft-switching parallel-loaded resonant converter which is characterized with simple structure, less component count, small volume, light weight, low cost, high efficiency and high power density, etc.
The high-frequency ac output produced by the parallel-loaded 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 based on the features of the circuit. The two active switches of the load resonant converter are controlled by pulse-width-modulation (PWM) controller. The converter is operated under continuous-conduction mode (CCM) by appropriate parameters design. Besides, the two power switches are turned on with the satisfactory features of zero voltage and zero current. Therefore, high efficiency can be achieved. The circuit parameters are decided according to the intrinsic impedance of the resonant tank. 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, an over-voltage detector is equipped in series with the battery to keep the battery from being over-charged in order to prolong its cycle life.
According to the switching operation and the configuration of the filter circuit, the operation modes and characteristic equations of the 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 battery charger. According to this equivalent circuit, the circuit parameter design equation and design procedure are deduced. Via computer simulation and completed circuit experiments, satisfactory results are received. Efficiency of this novel battery charger with parallel-loaded resonant converter for photovoltaic arrays is up to more than 80%.

並列關鍵字

Characteristic Impedance ； Photovoltaic Arrays ； Soft-Switching ； Charger ； Resonant Converter

參考文獻

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