移相控制ZVS PWM DC-DC全桥变换器软开关技术及应用

【作者】 龙泳涛；

【导师】 陈宗穆； 方厚辉；

【作者基本信息】 湖南大学 ， 电工理论与新技术， 2002， 硕士

【摘要】 论文简要介绍了开关电源软开关技术的发展历程。在分析了PWMDC-DC全桥变换器的基本工作原理之后，系统地提出了它的九种控制方式和两类软开关实现方式。本文只讨论移相控制方式和ZVS软开关实现方式。文中详细分析了基本的移相控制ZVS PWM DC-DC全桥变换器的工作过程，讨论了移相控制ZVS PWM DC-DC全桥变换器的零电压开关条件、副边占空比丢失以及整流二极管的换流情况，指出基本的移相控制 ZVS PWM DC-DC全桥变换器的不足：滞后桥臂实现零电压开关比较困难；副边占空比丢失严重。为解决这些问题，介绍了利用饱和电感来减少副边占空比丢失的方法并分析了带饱和电感的移相控制 ZVS PWMDC-DC全桥变换器的工作过程。介绍了给滞后桥臂增加辅助电路以改善滞后桥臂开关管的软开关环境的方法，并详细分析了一种带辅助网络的移相控制 ZVS PWM DC-DC全桥变换器的工作过程。它具有辅助电路简单，辅助电路的电感、电容和二极管的电流电压应力小，副边占空比损失小等优点。介绍了桥式变换器的不平衡问题及解决方法和参数确定。最后，介绍了移相控制 ZVS PWM DC-DC全桥变换器的电路元器件参数的选取及控制芯片UCX875 的工作原理，以原邮电部行业标准“YD/T731-94”为标准初步设计了一个通信用48V/10A的开关电源，并给出SPICE仿真结果，表明该电源达到设计指标。更多还原

【Abstract】 This paper briefly reviews the development of soft-switching technique applied to switch power supply. The operation principle of pulsewidth-modulated (PWM) DC-DC full-bridge (FB) converter is analyzed, and then the nine control methods and the two ways to achieve soft-switching are put forward systematically. In this paper, we only discuss phase-shifted (PS) control and zero-voltage switching (ZVS). The operation principle of the classical PS ZVS PWM DC-DC FB converter is analyzed, then the requirements of its operating under ZVS, its transformer secondary side duty cycle loss and the conditions of current commutation in output diodes are discussed.The classical PS ZVS PWM DC-DC FB converter has some disadvantages such as its lagging leg is difficult to achieve ZVS and its duty cycle loss is large. To alleviate these problems, this paper introduces a PS ZVS PWM DC-DC FB converter using saturable inductor to reduce its duty cycle loss. This paper also introduces a PS PWM DC-DC FB converter with an auxiliary network attached to its lagging leg. This auxiliary network has the advantages such as its circuit is simple, the current stresses and voltage stresses on its components are small. The question of unbalance on PS PWM DC-DC FB converter is discussed, and the solution is proposed.The PS PWM DC-DC FB converter s key parameters are calculated and the control 1C UCX875 is introduced. Finally, a 48V/10A switch power supply applied to communication system is designed to meet the requirements of the standard "YC/T731-94" . The scheme is verified by SPICE simulation.更多还原