推挽变压器输出阻抗及阻抗匹配方法分析

Analysis on the Output Impedance and Impedance Matching Method of Push-pull Transformer

推挽变压器构成的功率变换器由于其交直流分离,开关器件少等优点在实际工程项目中应用广泛。结合多线圈变压器线圈漏感时空属性以及工作模态切换理论分析了推挽变压器的输出阻抗,提出用分段函数来表示其输出阻抗,并通过平均输出阻抗来代替时变的输出阻抗。实验显示在直流源24 V供电下,相比传统次级漏感谐振法天线端谐振电压峰-峰值提升了25.64%,相比直接连接法谐振电压峰-峰值提升了46.26%;初级电流相较传统的次级漏感谐振法提升了14.6%,相较不匹配法,初级电流提升了33%。证明在此提出的平均输出阻抗匹配法既满足共轭匹配的要求,又有效改善了推挽逆变电路模块之间的匹配特性,进而提升了逆变电路的性能。同时对于推挽变压器输出阻抗以及阻抗匹配方法的研究有利于把握变压器外特性和推挽类功率变换器的控制设计。

The power converter composed of push-pull transformer is widely used in practical projects because of its AC/DC separation and less switching de vices.The output impedance of push-pull transformer is analyzed based on the time-space property of multi coil transformer leakage inductance and working mode switching theory.The piecewise function is proposed to represent the output impedance,and the average output impedance is used to replace the time-varying output impedance.The experimental results show that the peak to peak value of resonant voltage at antenna end is increased by 25.64%compared with the traditional secondary side leakage inductance resonance method and 46.26%compared with the direct connection method when the DC source is 24 V power supply.The index of inverter main circuit current is increased by 14.6%compared with the traditional secondary side leakage inductance resonance method,and the primary side current is more than 33%as much as that of the mismatched method.lt is proved that the average output impedance matching method proposed not only satisfies the conjugate matching,but also effectively improves the matching characteristics between the push-pull inverter circuit modules,and then improves the performance of the inverter circuit.At the same time,the research on the output impedance and impedance matching method of push-pull transformer is helpful to grasp the external characteristics of transformer and the control design of push-pull power converter.