【作者】 杨瑞；

【导师】 丁洪发；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2012， 硕士

【摘要】 串并联谐振变换器具有软开关特性，能消除变压器寄生参数的影响，广泛应用在高压直流电源和分布式DC/DC电源领域。串并联谐振变换器有断续电流和连续电流两种工作模式，利用基波近似法能得到处于连续电流模式的串并联谐振变换器的稳态模型。而在断续电流模式下，谐振电流畸变明显，基于基波近似的稳态模型不能够准确反映变换器的工作过程和电气特性。为解决断续电流模式下串并联谐振变换器的稳态建模问题，本文提出了一种分段式的描述方程，来表征处于断续电流模式下变换器的输出电压、开关频率、负载三者之间的关系。断续电流和临界电流模式下串并联谐振变换器的响应有着相似的规律，本文首先在临界电流模式下，利用状态空间法求解谐振电路的响应，得到满足负载侧整流电流双脉冲、单脉冲两种形式的输出电压约束条件。以稳态时负载的能量平衡方程为基础，求解出输出电压系数、临界开关频率、负载品质因数三者之间的函数关系，进一步得到了临界电流模式下变换器的电压增益与开关频率间的关系。引入断续电流系数，将临界电流模式下的分段式描述方程扩展到断续电流模式，提出了变换器的分段式稳态模型。该模型能准确反映串并联谐振变换器的响应随负载和开关频率的变化情况，可以用来指导串并联变换器的设计。针对两种不同的应用，本文提出了基于分段式描述方程的SPRC设计步骤，验证了设计的正确性。更多还原

【Abstract】 Series-parallel resonant converter (SPRC), which has a good soft-switchingperformance and capability of absorbing the parasitic parameters, is widely used in highvoltage DC power supply systems and distributed DC/DC applications. Continuous currentmode (CCM) and discontinuous current mode (DCM) are the two different operationmodes of SPRC. The fundamental harmonic approximation is a simple and effectivemethod to establish the steady-state model of SPRC operating in CCM, yet not suitable inDCM for the approximation error resulted from the serious sinusoidal distortion.In order to solve steady-state model of the SPRC operating in DCM, this paperproposes a piecewise description function, which represents the characteristic among theoutput voltage, the switching frequency and the load.In the just continuous current mode, the response of the resonant circuit is solved bythe state space method. The constraint relation in double pulses form and single pulse formis obtained separately. Based on the energy balance equation, a piecewise functionalfunction among the output voltage coefficient, the JCCM switching frequency and the loadquality factor is derived. In addition, the voltage gain characteristics of the SPRC is alsopresented. Via discontinuous coefficient, the piecewise function in just continuous currentmode is extended to the DCM, and it can accurately describe the steady-state behavior ofthe SPRC operating in DCM, providing a favorable way for designing the series-parallelresonant converter. Considering two applied situations, the design procedure based on thepiecewise function is given, and then, a digital simulation is established, verifying thecorrectness of the design procedure and the piecewise description function.更多还原