【作者】 刘战涛；

【导师】 张昆仑；

【作者基本信息】 西南交通大学 ， 电磁悬浮与超导工程， 2008， 硕士

【摘要】 磁悬浮列车是一种新型的轨道交通运输工具,它利用电磁吸力或电动斥力将列车悬浮在轨道上方,与地面无机械接触,具有速度快、能耗低、舒适、噪音小等特点,因此是未来一种极具发展潜力的现代化交通工具。现有的磁浮列车悬浮系统可分为电磁吸力悬浮(EMS)和电动斥力悬浮(EDS)2种基本的悬浮方式。电磁吸力悬浮的悬浮力全部由电磁铁提供,在运行中能量的消耗非常大,而且影响悬浮气隙的进一步增大。为解决这些问题,我们采用混合悬浮系统,它是永久磁铁和电磁铁结合的悬浮系统,稳定悬浮时所需的静态平衡力由永久磁铁提供,而动态平衡力则由常导线圈提供,电磁铁要既能提供正向力又能提供反向力,即悬浮斩波器不但要能提供正向电流,又要能提供负向电流,故使用四象限斩波器。把软开关技术应用到悬浮斩波器中可以带来明显的好处,减小了系统损耗,提高了系统的电源变换效率。本文首先介绍了四象限悬浮斩波器各基本组成部分的相关特性,包括续流二极管的特性、IGBT的特性、IGBT的驱动和保护。其次,对软开关技术及分类做了简单介绍,在软开关变换器和悬浮斩波器主电路的基础上设计出了四象限零电压开关PWM和零电压转换PWM软开关悬浮斩波器,并对其工作原理和参数进行了详细的分析和设计。再次,运用电路仿真软件PSpice对软开关悬浮斩波器进行了建模和仿真,并对比性地仿真了硬开关斩波器系统。仿真结果表明软开关变换器能有效地改善主电路的开关特性,减小了主电路器件的电压应力和电流应力。最后对负载的动态特性进行建模仿真,负载的变化与期望值相一致,满足负载动态特性的要求。零电压开关PWM软开关斩波器的主功率器件可以完全实现零电压开通和关断,减小了系统损耗,与负载的性质和程度没有关系,但是辅助管本身是硬开关,有一定的损耗,其缓冲电路和谐振电感的共同作用给母线电压带来了较大的尖峰。零电压转换PWM软开关斩波器实现了主开关管的零电压转换,开关管工作条件大大改善。更多还原

【Abstract】 Maglev train is a new type of vehicle on railway track. It levitated over the rails by electromagnetism suction or repulsion, the body of the train does not touch the ground, As a perfect vehicle on land, maglev train is characterized by high velocity, less energy consuming, lower noise, safety and comfort. Therefore, it is potential modern transportation vehicle in the future. The current maglev train suspension systems include two basal structures, EMS and EDS. The suspending power of EMS is complete provided by electromagnet, therefore, energy loss cannot be ignored, and the enlargement of gap is limited and a higher rail precision is required. Aiming at the problems, this dissertation designs hybrid electromagnetic suspension(EMS) systems, it is a combination of permanent magnet and electromagnet, static counterbalance is provided by permanent magnet and dynamic counterbalance is provided by electromagnet when it suspend steadily. The electromagnet not only provided magnetism, but also suspension, maglev chopper not only provided positive current, but also provided negative current, so use four-quadrant maglev chopper. There are obvious advantages to apply soft-switching technology to maglev, it has little switching losses and the efficiency of the chopper can be improved.Firstly, this paper introduces the characters of basic components of four-quadrant maglev chopper which including the character of freewheeling diode, the character of IGBT, the drive and protection of IGBT. Secondly, ordinary introduces the sort of soft-switching, design four-quadrant maglev chopper of zero-voltage-switching PWM converter and zero-voltage-transition PWM converter based on soft-switching and maglev chopper, analyzes the characteristics of soft-switching chopper and design its parameters detailedly. Secondly, modeled and simulated the converter structures by PSpice and compared their advantages and disadvantages. The result proves that the soft-switching converter can improve the switch characteristic of main circuit. It also can decrease the switch stress and current stress of switch equipment. Lastly, modeled and simulated the transient response of load, the result isconsistent with expectation, and has a good speciality of transient response.The main-switches of the zero-voltage-switching PWM soft-switching chopper have zero-voltage turn-on and turn-off totally, so it has little switching losses. The realization of the ZVS has no concerned with the attribute of load. But, as the chopper provides the ZVS condition with an assistant switch, which work in hard switching, it has some losses in switching even using a snubber network. There is another more, the snubber can be resonant with the inductor, that brings on a huge spike on the source voltage. The zero-voltage-transition soft-switching PWM soft-switching chopper realizes the zero-voltage transform of main switch, the working conditions of switch improve greatly.更多还原