【作者】 屈旭光；

【导师】 孔力；

【作者基本信息】 中国科学院研究生院（电工研究所） ， 电力电子与电力传动， 2004， 硕士

【摘要】 开关电源由于其体积小，重量轻，功率密度大，工作性能良好得到日益广泛地应用。开关频率的提高，造成了不可避免的电磁干扰问题，同时功率开关管的损耗也增加了。如何改善功率开关管的工作环境，降低功率开关管在开通和关断瞬间的电压和电流应力，一直以来是人们研究的热点。 解决开关损耗的有效途径是采用软开关技术。根据有无辅助开关管可以将软开关技术分为有源软开关技术和无源软开关技术．无源软开关技术又可以根据有无损耗分为无源有损耗软开关技术和无源无损软开关技术。有源软开关技术能够实现真正意义上的软开关，在开关管开通时提供零电压或者零电流开通，在开关管关断时提供零电压或者零电流关断，有效地解决了开关损耗问题，提高了变换器的变换效率。但是有源软开关技术因为有辅助开关管的引入，控制电路比较复杂，增加的额外元器件较多，变换器成本增加。采用无源无损软开关技术，可以实现开关管开通时的零电流开通和关断时的零电压关断，实现软开关功能，改善开关管工作条件，提高变换器工作效率。原电路的控制电路没有大的变动，增加的额外元器件较少，成本较低。所以也得到日益广泛的应用。 本文在深入分析了产生开关损耗和电磁干扰问题原因的基础上，以有源功率因数校正电路为平台，研究了一种具有最小电压应力的无源无损软开关结构。对电路进行了工作模态分析，对于软开关的实现条件进行了讨论，给出了无源无损软开关环节参数的设计原则。本文中采用SABER仿真软件对该环节进行了仿真分析，仿真结果表明，这种结构能够实现开关管开通时的零电流开通和关断时的零电压关断。 本文中对于平均电流模式控制的工作原理和具体实现进行了深入分析。 小信号分析法是研究功率变换器的有效方法。小信号模型的建立，可以使得人们彻底认识变换器的工作过程，同时通过小信号模型可以获得输入，输出和控制之间的传递函数，为控制电路的设计提供条件。本文对于变换器功率电路部分进行了小信号建模和分析，给出了小信号特性传递函数。 本论文最后搭建了一个功率为250W的有源功率因数校正变换器来验证理论分析和仿真分析结论，实验中采用宽范围可调节电压源作为输入，输出为恒定直流电压。实验结果表明所研究的无源无损软开关环节能够实现在开关管开通时的零电流开通和开关管关断时的零电压关断。并且这个环节在输入电压宽范围变化时仍然能够实现软开关功能。软开关环节的存在没有影响电路功率因数校正的功能，电路能够实现很高的功率因数，谐波含量也满足设计要求。文中给出了仿真分析和实验波形，实验波形和仿真波形以及理论分析的波形基本上是吻合的。更多还原

【Abstract】 Switch-mode-power-supply (SMPS) has been widely used because of its small volume, light weight, high power density and good performance. With the enhancement of frequency, Electro-Magnetic Interference (EMI) problem produces, the dissipation of the main power switch increases as well. How to improve the operation circumstance of the switch, how to decrease the current and voltage stress of the main switch during turn on and turn off transient, become one of the focus people study.The efficient approach to solve switching dissipation is to use soft switching technique. It can be classified into two groups of active and passive according to the use of additional switch. The passive one can also be classified into passive dissipation and non-dissipation. The active soft-switching method can achieve real soft switch, provides zero voltage or zero current turn on, zero current or zero voltage turn off. It can solve power dissipation efficiently and improve the efficiency of the converter. Because of introduction of the additional switch, the control circuit of the converter becomes complex and the amount of the added parts and cost increases. While using passive lossless soft switching technique, the zero current turn on and zero voltage turn off of the main switch can be achieved, the efficiency of the converter is improved as well. The control circuit of the original converter is not changed too much, the amount of the added parts is small, and the cost is reduced. So it will be used widely.In this thesis, the reason that leads to the dissipation of the switch and EMI was deeply analyzed. One topology of a so-called passive, lossless soft-switching technique with minimum voltage stress was studied and applied to APFC circuit. The operation mode of the circuit is analyzed and the condition of how to achieve soft switch is discussed, how to design the parameters of the snubber is presented as well. SABER was used to simulate the operation of this soft-switching topology, the result showed that it could achieve zero current switchingwhen the main switch turned on and zero voltage switching when it turned off.The principle and implementation of the average current mode control was deeply analyzed in this thesis.Small signal analysis is an efficient tool for the study of power converter. After building a small signal model of a converter, one can deeply and thoroughly study its operation process. The transfer functions between input, output and control can be presented. These transfer functions are the premise of design the control circuit. In this thesis the small signal model of the power stage of the converter was established and analyzed, the relative transfer functions were presented.A prototype of a 250W APFC converter was established to validated the theory analysis and simulation result. A wide adjusted power was used as the input, the output was a constant DC voltage. The result showed that the studied passive lossless soft-switching technique could achieve zero current switching when the main switch turned on and zero voltage switching when it turned off in wide input voltage range. The existence of the soft- switching had no effect on the converter to get high quality factor, and the THD could achieve therequirement as well. Simulation and experiment waveforms were presented, the two formerand the theoretical waveform were basically in consistent.更多还原