DESIGN OF HIGH VOLTAGE POWER CONVERTER FOR TRAVELING WAVE TUBE AMPLIFIER

Traveling Wave Tubes(TWTs) are widely used in the radar and communications system as RF power amplifiers. A highly sophisticated power supply is required by TWT. In order to meet the severe requirements of Traveling Wave Tube Amplifier(TWTA), a novel two-stage topology high voltage converter for TWTA is proposed.The converter is based on Zero-Voltage Switching and Zero-Current Switching(ZVS/ZCS) resonant techniques. The high voltage converter operation principles are investigated and major features of the converter are discussed. The power switching mode of ZVS/ZCS is obtained. The experimental results show that the converter has good soft switching characteristics. Compared to the conventional hard switched Pulse Width Modulation(PWM) techniques, the high efficiency and low ripple of the converter for TWTA are realized. The efficiency of High Voltage Electronic Power Conditioners(HV-EPC) over 93.5% under the condition of 38~46 V input voltage and 260~300 W input power. The switching frequency of first-stage(preregulator) of HV-EPC is 89 k Hz and the switching frequency of second-stage(postregulator) is 44.5 k Hz. The highest output voltage of the HV-EPC is helix voltage which is about –6.8 kV. It is especially suitable for TWTA utilized in space satellite applications due to its high switching frequency and high power density.     

一种同步整流有源箝位正激变换器的研究

提出一种同步整流有源箝位正激变换器。该变换器是在传统的同步整流有源箝位正激变换器的原边增加一个由箝位电容和电感构成的辅助网络得到。该辅助网络可以使变换器在全负载范围内更容易实现主开关管和辅助开关管的ZVS(Zero-Voltage Switching),副边采用自激式同步整流技术,能进一步提升变换器效率,适用于低压、大电流输出场合。详细分析了变换器的工作原理,搭建了一台8 V/100 W试验样机证明了理论分析的正确性。     

基于耦合电感的四相交错Buck变换器研究

基于耦合电感的四相交错Buck变换器是由4个同步Buck变换器通过磁耦合技术并联组成。在分析其工作原理、软开关条件以及设计耦合电感的基础上,以TMS320F28035作为控制核心,搭建了一台16 kW的实验样机。实验结果表明,该变换器在移相（PS）PWM控制策略下,开关管电流应力小,电流纹波明显减小,可在全负载范围内实现零电压开关（ZVS）,适用于低压大电流、大功率应用场合。     

不对称半桥变换器的小信号建模与仿真研究

不对称半桥变换器利用自身的寄生器件实现了开关管的零电压操作,在不影响电路整体结构,以及不增加成本的前提下达到了很好的输入、输出特性。文章建立了该类变换器的小信号模型,进行了动态分析、仿真研究及补偿回路设计,并对整体的电路稳定性和几个关键的频率特性进行了研究。     

电流模式控制倍流整流器ZVS PWM 全桥DC-DC变换器

采用电流模式移相PWM控制,在较大的负载范围内实现了开关器件的零电压软开关(ZVS).给出了实验结果.     

基于单片机的准谐振开关电源的设计

利用AVR AT90PWM2单片设计了一种准谐振开关电源。阐述了准谐振开关电源的原理和优点,给出了电路原理图,以及单片机关键寄存器的设置和说明。试验结果证明了该设计的可行性和有效性。     

一种宽输入电压范围软开关电流型DC/DC转换器

针对太阳能光伏及燃料电池等领域电源需要较宽输入电压范围的需求,提出一种通用的具有较宽输入电压范围的软开关电流型DC/DC转换器。该转换器采用了固定频率混合调制设计,可以在所有工作条件下实现半导体器件的软开关工作,并采用电流馈电技术以便适用于低电压高电流的电源。相较于传统转换器,该转换器更为通用,能够实现零电压开关和零电流开关,并且能够在输入电压和负载变化出现较大变化时控制输出电压。实验结果显示,在20-60V输入电压范围内且负载出现变化时,该转换器均表现出良好的性能。     

采用ZVS条件控制的DC-DC同步整流技术

以Buck结构DC-DC为例,结合仿真波形分析了DC-DC一个开关周期4个阶段的电流电压情况,证明由ZVS条件控制MOS管的导通和断开是损耗最小的。由此提出了两种实现ZVS控制的电路拓扑：同步反馈控制以及由程序综合的控制电路。并与自适应控制进行了比较。同步反馈控制利用时钟和ZVS条件,结合MUX实现了导通和关断的理想波形。由程序综合的控制电路以PWM控制和ZVS控制为目标,并由时钟同步,实现了对驱动波形的控制。     

四种典型的改进型ZVS全桥变换器的研究

移相全桥变换器具有开关器件电压应力小、功率变压器利用率高等特点,目前常被应用在中大功率的开关电源中.本文主要针对基本移相控制ZVS全桥变换器拓扑结构优缺点,介绍四种典型的改进方案,并对这四种典型电路的拓扑结构的优缺点进行了对比.     

Design of auto-tuning capacitive power transfer system for wireless power transfer

This paper presents the design of capacitive wireless power transfer systems based on a Class-E inverter approach. The main reason for adopting the Class-E inverter approach is because of its high efficiency, theoretically 100%. However, the operation of a Class-E inverter is highly sensitive to its circuit’s parameters. In a typical capacitive wireless power transfer application, the capacitive coupling distance between plates is subject to changes, and hence its power transfer efficiency is greatly affected if the Class-E inverter is properly tuned. This drawback motivates us to develop an auto frequency tuning algorithm for a Class-E inverter which maintains its power transfer efficiency in spite of the variations of capacitive coupling distances between plates and circuit’s parameters. Finally, simulation and experiment are carried out to verify the effectiveness of the auto frequency tuning algorithm.