LLC諧振變換器的控制與仿真
發(fā)布時間：2018-08-30 18:11
【摘要】：從目前來看,由于環(huán)境污染新能源的使用越來越廣泛。光伏發(fā)電就是目前使用新能源的一種主要方式,而諧振功率變換器在光伏發(fā)電中起了重要作用,尤其是LLC諧振變換器。例如LLC諧振變換器可以應用于雙階段短時間光伏系統(tǒng),將輸入的不穩(wěn)定的直流電壓轉(zhuǎn)換為穩(wěn)定的直流電壓。對于一般的功率變換器,為了提高能量傳遞效率增大開關(guān)操作頻率,但增大開關(guān)操作頻率時開關(guān)損耗也會增加,而在低頻率下磁組件電容器成本又會很高,此外對于光伏電池板的寄生電容由于缺乏隔離可能導致泄漏電流,但LLC諧振變換器用于這類系統(tǒng)可以很好的克服這些問題。本文對LLC諧振變換器的建模,控制算法和仿真三個方面進行研究。對于一個典型的LLC變換器具有一個相對精確的非線性動力學模型是必要的,從而確定小信號模型還有傳遞函數(shù)。在建模過程中,首先由電路定律寫基本微分方程;LLC諧振電路的電壓電流是準正弦電流和電壓波形,電磁感應電流和諧振池電容器的電壓由正余弦基本部分組成,將這些交流量近似為其基波成分;通過諧波平衡分離正弦和余弦分量的系數(shù)得到的近似大信號模型;一個大信號模型諧波平衡可以用來獲得穩(wěn)定狀態(tài)的工作點,通過設置平衡方程的導數(shù)項為零;諧波平衡方程的線性化將系統(tǒng)方程一階近似,最后求出傳遞函數(shù)。設計合理的控制器使系統(tǒng)在輸入電壓、共振池參數(shù)、輸出負載等擾動下調(diào)節(jié)共振池的增益,保證系統(tǒng)的輸出電壓始終追隨參考電壓。在LLC諧振變換器的控制研究部分,設計一個單環(huán)或雙環(huán)反饋控制回路,根據(jù)參考電壓以調(diào)節(jié)輸出電壓。本文所設計的LLC諧振變換器控制器的輸出都是用于控制開關(guān)操作頻率,因此這是一種通過改變開關(guān)操作頻率來控制共振池增益的方法。在諧振變換器的控制方面分別設計了帶有補償器的雙環(huán)控制器、模糊邏輯控制器和滑�？刂破�,并且針對每一個控制器搭建了仿真模型,比較不同控制器的控制效果。
[Abstract]:From the current point of view, due to environmental pollution, the use of new energy is becoming more and more widespread. Photovoltaic power generation is one of the main ways to use new energy at present, and resonant power converters play an important role in photovoltaic power generation, especially LLC resonant converters. For example, LLC resonant converters can be used in two-stage short-time photovoltaic systems to convert the input unstable DC voltage into a stable DC voltage. For general power converters, in order to improve the efficiency of energy transfer, the switching frequency is increased, but the switching loss will also increase when the switching frequency is increased, and the cost of magnetic component capacitors will be very high at low frequency. In addition, the parasitic capacitance of photovoltaic panels may lead to leakage current due to the lack of isolation, but the LLC resonant converter used in this kind of system can overcome these problems. The modeling, control algorithm and simulation of LLC resonant converter are studied in this paper. It is necessary for a typical LLC converter to have a relatively accurate nonlinear dynamic model to determine the small signal model as well as the transfer function. In the process of modeling, the voltage and current of the LLC resonant circuit are quasi sinusoidal current and voltage waveform, and the electromagnetic induction current and the voltage of the resonant cell capacitor are composed of sine cosine. These AC quantities are approximated to their fundamental wave components; an approximate large signal model is obtained by separating the coefficients of sine and cosine components from harmonic balance; and a large signal model harmonic balance can be used to obtain working points in a stable state. By setting the derivative term of the equilibrium equation to zero and linearizing the harmonic equilibrium equation, the first order approximation of the system equation is obtained and the transfer function is obtained. A reasonable controller is designed to adjust the gain of the resonant cell under the disturbance of input voltage, resonant cell parameters and output load, so as to ensure that the output voltage of the system always follows the reference voltage. In the control research of LLC resonant converter, a single loop or double loop feedback control loop is designed to adjust the output voltage according to the reference voltage. The output of the LLC resonant converter controller designed in this paper is used to control the switching frequency, so it is a method to control the gain of the resonant cell by changing the switching frequency. In the aspect of resonant converter control, double loop controller with compensator, fuzzy logic controller and sliding mode controller are designed, and simulation models are built for each controller to compare the control effect of different controllers.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM46
本文編號：2213883
[Abstract]:From the current point of view, due to environmental pollution, the use of new energy is becoming more and more widespread. Photovoltaic power generation is one of the main ways to use new energy at present, and resonant power converters play an important role in photovoltaic power generation, especially LLC resonant converters. For example, LLC resonant converters can be used in two-stage short-time photovoltaic systems to convert the input unstable DC voltage into a stable DC voltage. For general power converters, in order to improve the efficiency of energy transfer, the switching frequency is increased, but the switching loss will also increase when the switching frequency is increased, and the cost of magnetic component capacitors will be very high at low frequency. In addition, the parasitic capacitance of photovoltaic panels may lead to leakage current due to the lack of isolation, but the LLC resonant converter used in this kind of system can overcome these problems. The modeling, control algorithm and simulation of LLC resonant converter are studied in this paper. It is necessary for a typical LLC converter to have a relatively accurate nonlinear dynamic model to determine the small signal model as well as the transfer function. In the process of modeling, the voltage and current of the LLC resonant circuit are quasi sinusoidal current and voltage waveform, and the electromagnetic induction current and the voltage of the resonant cell capacitor are composed of sine cosine. These AC quantities are approximated to their fundamental wave components; an approximate large signal model is obtained by separating the coefficients of sine and cosine components from harmonic balance; and a large signal model harmonic balance can be used to obtain working points in a stable state. By setting the derivative term of the equilibrium equation to zero and linearizing the harmonic equilibrium equation, the first order approximation of the system equation is obtained and the transfer function is obtained. A reasonable controller is designed to adjust the gain of the resonant cell under the disturbance of input voltage, resonant cell parameters and output load, so as to ensure that the output voltage of the system always follows the reference voltage. In the control research of LLC resonant converter, a single loop or double loop feedback control loop is designed to adjust the output voltage according to the reference voltage. The output of the LLC resonant converter controller designed in this paper is used to control the switching frequency, so it is a method to control the gain of the resonant cell by changing the switching frequency. In the aspect of resonant converter control, double loop controller with compensator, fuzzy logic controller and sliding mode controller are designed, and simulation models are built for each controller to compare the control effect of different controllers.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM46
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