【作者】 邱兴云；

【导师】 陆治国；

【作者基本信息】 重庆大学 ， 电气工程， 2003， 硕士

【摘要】 为了满足功率变换器的小型化、轻量化、模块化的发展趋势，软开关技术已成为电力电子技术的热点之一。“软开关”是指零电压开关或零电流开关，它是利用谐振原理，使开关变换器的开关管电压(或电流)按正弦(或准正弦)规律变化，当电压过零时，使器件开通(或电流自然过零时，使器件关断)，实现开关损耗为零，从而提高开关频率，减小变压器、电感的体积。虽然，软开关技术能够实现功率变换器的小型化、模块化等，但是，电路变得更加复杂，使得中小功率的变换器的成本增加，往往不利于商业竞争。本文研究了一种零电压的不对称半桥拓扑结构，它可以在不增加电路成本的基础上，利用电路自身的特点，实现软开关。 本文所做的主要工作如下： (1) 对不对称半桥主电路工作原理进行分析，给出了占空比与输出电压、输入电压的关系以及消除变压器偏磁的方法。 (2) 对不对称半桥在一个完整的开关周期内各个状态分析，描述了隔直电容电压和变压器漏感电流的变化规律，各个状态的持，然后得出实现ZVS的条件，从而为设置合理的死区时间提供了理论指导，最后用Saber软件进行了仿真，验证了零电压开关实现的可能性。 (3) 不对称半桥DC／DC变换器的建模分析 采用状态空间平均法建立了不对称半桥变换器功率级的小信号平均电路模型，在此基础上建立整个变换器系统模型，对系统的动态特性和稳定性进行了分析并设计了补偿器。 最后，用Matlab软件进行仿真，验证了整个系统的稳定性，用Saber软件仿真，验证了系统的动态性能。 (4) 不对称半桥的实验电路设计及实验结果 基于前面的分析，设计了一个不对称半桥DC／DC变换器的实验电路，进行了实验研究，实验结果证实了在满足死区和负载电流两个条件时，不对称半桥可以实现零电压开关。更多还原

【Abstract】 Soft switching technology has been one of the hot points of power electronic technologies for smaller and lighter and modularization converter. "Soft switching" is zero voltage switching or zero current switching, which the voltage (or current) of the switch varies by law of sine or quasi sine, the switch is on when its voltage reaches zero (or switch is off when its current reaches zero) by resonance. It makes switch loss is zero, so it can increase the operating frequency and raise power density, minimize the size of transformer and inductor. However, it makes the circuit complex, which means it cost more, which affects the competitiveness of commercial product. A topology of asymmetrical half bridge soft switching is researched in this thesis, which has inherent zero voltage switching (ZVS) capability and thus potentially higher efficiency by its resonating of the leakage of power transformer with the parasitic capacitances of the power MOSFT switches, whereas it doesn’t raise the expense of the converterThese studies in the thesis have been done as follows:(1) The topology of asymmetrical half bridge is introduced, and its principle and the relation of duty cycle and input voltage and output voltage discussed, the method of eliminating the deflection magnetism is also brought forward .(2) Each state of the total switching period has been studied in detail, in which the voltage of block capacitor and current of leakage inductance of main transformer and keeping time of each state have been discussed, then the condition of zero voltage switching is attained, which gives theory guidance for setting reasonable dead time, finally, the possibility of zero voltage switching is proved by simulation of Saber software.(3) Modeling of the asymmetrical half bridge converterIn the thesis, a small average circuit model of asymmetrical half bridge converter power stage is established by method of state space averaging. In term of it, a system model of total converter is founded. The characteristic of stabilization and dynamic is analysed and the compensator is designed basing of it.The stability of the converter is validated by simulation of Matlab and dynamic approved by simulation of Saber.(4) The experiment of asymmetrical half bridge converter design and the result of it Base of the above analysis, the DC/DC converter is designed, it is proved thatasymmetrical half bridge can realize zero voltage switching when it satisfies the condition of load current and deadtime by the experiment.更多还原