【摘要】：在燃料電池發(fā)電系統(tǒng)中,要求前端DC/DC變換器具有適應(yīng)寬范圍電壓變化的輸入特性、提供高電壓增益的輸出特性、實(shí)現(xiàn)電氣隔離的功率傳輸特性和寬負(fù)載范圍的軟開關(guān)特性。本課題依此設(shè)計(jì)要求,對混合移相控制的全橋變換器進(jìn)行了研究。本文設(shè)計(jì)了一種基于新型三電平結(jié)構(gòu)的全橋變換器,并加入輔助電流源電路,提高了電壓增益,減小了器件應(yīng)力,實(shí)現(xiàn)了原邊開關(guān)管的寬范圍軟開關(guān)。應(yīng)用混合移相的控制策略,即變換器工作在Boost模式時(shí)副邊移相控制,工作在Buck模式時(shí)雙重移相控制,拓寬了輸入電壓的可調(diào)節(jié)范圍,消除了二極管電壓尖峰。同時(shí)減小了原邊環(huán)流損耗,實(shí)現(xiàn)了副邊開關(guān)管全工作模式下的軟開關(guān),提升了變換器效率。通過對變換器各個(gè)工作模式的穩(wěn)態(tài)特性分析,詳細(xì)說明了輸出特性、軟開關(guān)特性和無功環(huán)流特性與電路相關(guān)參數(shù)的關(guān)系,為電路的參數(shù)設(shè)計(jì)和控制提供了依據(jù)。采用擴(kuò)展函數(shù)描述法和降階等效電路法建立了變換器的小信號模型,對比分析后以降階模型設(shè)計(jì)了閉環(huán)補(bǔ)償網(wǎng)絡(luò),使得系統(tǒng)具有更高的穩(wěn)態(tài)精度和更快的動(dòng)態(tài)響應(yīng)。最后,對變換器進(jìn)行仿真,驗(yàn)證了各個(gè)模式下工作過程和相應(yīng)穩(wěn)態(tài)特性分析的正確性。制作了一臺輸入電壓40V-80V,輸出電壓300V,開關(guān)頻率100k Hz,輸出功率300W的實(shí)驗(yàn)樣機(jī)。采用DSP作為主控制器,對數(shù)字控制部分進(jìn)行了設(shè)計(jì)。實(shí)驗(yàn)測試結(jié)果表明:變換器能夠在寬范圍的輸入電壓下保持輸出電壓的穩(wěn)定,并實(shí)現(xiàn)了原副邊開關(guān)管全工作模式下的軟開關(guān),同時(shí)具有良好的動(dòng)態(tài)性能,達(dá)到了預(yù)期的設(shè)計(jì)要求。
[Abstract]:In the fuel cell power generation system, the front-end DC/DC converter is required to have input characteristics that adapt to the wide range voltage variation, provide the output characteristics of high voltage gain, realize the power transmission characteristics of electrical isolation and soft switching characteristics of wide load range. According to the design requirements, this paper studies the hybrid phase-shifted full-bridge converter. In this paper, a novel three-level full-bridge converter is designed, and the auxiliary current source circuit is added to improve the voltage gain, reduce the device stress, and realize a wide range of soft switching of the primary side switch. The control strategy of mixed phase shift, that is, auxiliary side shift control when the converter works in Boost mode and double phase shift control when working in Buck mode, is applied to widen the adjustable range of input voltage and eliminate the diode voltage spike. At the same time, the loss of the primary circulation is reduced, and the soft switching of the auxiliary side switch is realized in full mode, which improves the efficiency of the converter. By analyzing the steady-state characteristics of each mode of operation of the converter, the relationship between the output characteristics, soft switching characteristics and reactive circulation characteristics and the circuit parameters is explained in detail, which provides the basis for the design and control of the circuit parameters. The small signal model of the converter is established by using the extended function description method and the reduced order equivalent circuit method. The closed-loop compensation network is designed by using the reduced order model, which makes the system have higher steady-state accuracy and faster dynamic response. Finally, the converter is simulated to verify the correctness of the operation process and the corresponding steady-state characteristic analysis in each mode. An experimental prototype with an input voltage of 40V-80V, an output voltage of 300V and a switching frequency of 100k Hz, output power of 300W is made. Using DSP as the main controller, the digital control part is designed. The experimental results show that the converter can keep the output voltage stable in a wide range of input voltages, and realize the soft switching of the primary and secondary side switches in full operation mode. At the same time, the converter has good dynamic performance. Meet the expected design requirements.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TM46
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本文編號：2376478