宽范围输出的副边移相控制全桥变换器的研究

发布时间：2018-04-10 18:51

本文选题：宽范围输出 + ZVS软开关　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：在电动汽车充电系统中,前级PFC(Power Factor Correction)装置输出电压范围有限,需要中间级DC-DC变换器才能满足充电需求。移相全桥拓扑简单、开关损耗小、可靠性高,是一种适合于大中功率场合的软开关拓扑。本文主要对宽范围输出的副边移相控制全桥变换器进行研究。对各种移相全桥拓扑进行了充分的分析研究之后,本文提出了一种带有无源辅助网络的副边移相控制全桥变换器。此变换器拓扑无需箝位电路就消除了整流二极管电压尖峰,提升了器件的可靠性;输出电容复位原边电流,消除原边续流损耗;引入副边移相控制策略,实现了副边二极管的ZCS(Zero Current Switch)自然换流;无源辅助网络的加入使得变换器原边开关管在空载条件下也能实现ZVS(Zero Voltage Switch)软开关,降低了开关损耗,提高了变换器效率。本文建立了移相角与变换器功率及输出电压的数学模型,并且论述了软开关条件,对电路参数与输出特性、软开关条件的关系进行了探讨。通过对比所有工作状态,可知DCM(Discrect Conduct Mode)工作状态回流功率为0,选择DCM工作状态作为变换器的主要工作状态。通过对移相电感、无源辅助网络等电路参数的优化设计,使变换器运行于所设定的工作状态,开关管在宽负载范围下实现ZVS软开关。利用开关周期平均法对变换器进行小信号建模,比较了二阶与一阶小信号模型,并在一阶小信号模型的基础上,设计合理的补偿网络和闭环系统控制电路,确保闭环系统稳定工作并且兼顾控制系统快速性。通过仿真和实验对本文的研究内容进行验证。制作了一台输入电压100 V,输出电压200 V-400 V,频率100 k Hz的实验样机,测试了所有工作状态下原边电感电流波形,验证了理论分析及仿真结果。其次在DCM工作状态下,验证了输出电压为200 V和400 V的不同载荷下的原副边开关管软开关特性。最后验证了切载时闭环控制系统的稳定性和快速性。实验结果达到预期设计目的及指标。
[Abstract]:In the electric vehicle charging system, the output voltage range of the front stage PFC(Power Factor correction device is limited, so the intermediate stage DC-DC converter is needed to meet the charging requirements.The phase-shifting full-bridge topology is simple, the switching loss is small, and the reliability is high. It is a soft switching topology suitable for large and medium power situations.In this paper, a wide range of output side-shift control full-bridge converter is studied.After a full analysis of various phase-shifted full-bridge topologies, this paper presents a kind of auxiliary side-shift full-bridge converter with passive auxiliary network.The converter topology eliminates the voltage spike of the rectifier diode without clamping circuit and improves the reliability of the device; the output capacitor resets the primary current to eliminate the current loss of the original side; and the secondary side phase shift control strategy is introduced.The natural commutation of ZCS(Zero Current switch of secondary side diode is realized, and the addition of passive auxiliary network makes the ZVS(Zero Voltage switch soft switch under the condition of no load, which reduces the switching loss and improves the efficiency of the converter.In this paper, the mathematical model of phase shift angle, converter power and output voltage is established, and the soft switching conditions are discussed. The relationship between circuit parameters and output characteristics, soft switching conditions is discussed.By comparing all the working states, it is known that the reflux power of DCM(Discrect Conduct mode is 0, and the working state of DCM is chosen as the main working state of the converter.By optimizing the circuit parameters such as phase-shifted inductor and passive auxiliary network, the converter runs in the set working state, and the switching tube realizes the ZVS soft switch in the wide load range.The switching cycle averaging method is used to model the converter with small signal. The second order and first order small signal models are compared. On the basis of the first order small signal model, a reasonable compensation network and closed-loop system control circuit are designed.Make sure the closed-loop system works stably and the control system is fast.The research content of this paper is verified by simulation and experiment.An experimental prototype with an input voltage of 100V, an output voltage of 200V-400V and a frequency of 100kHz is made. The waveforms of the primary side inductor current in all working states are tested, and the theoretical analysis and simulation results are verified.Secondly, the soft switching characteristics of the primary and secondary side switches under different loads with output voltages of 200V and 400V are verified in the state of DCM.Finally, the stability and rapidity of the closed loop control system are verified.The experimental results reach the expected design goal and target.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM46;U469.72

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