【作者】 王冬冬；

【导师】 刘克富；

【作者基本信息】 华中科技大学 ， 脉冲功率与等离子体， 2008， 硕士

【摘要】 对以电容器作为储能单元的脉冲功率系统来说,电容器充电电源的性能决定了输出电压的稳定度和重复频率。高频谐振变换器用于电容器充电时具有诸多优势,在对大容量电容充电时以串联谐振变换器应用得最为普遍。本论文介绍了应用于脉冲等离子体推进器的串联谐振电容器充电电源的研制。通过对谐振电路的稳态分析,得到了工作于不连续电流模式的串联谐振电容器充电电路中谐振电流峰值、谐振电压峰值和负载电容电压增量与谐振周期的个数之间的函数关系,证明在续流电流峰值降到零之前,电路具有内在的恒流特性,因此能够实现线性充电。此外还计算出了恒流特性发生变化的时刻以及该时刻对应的负载电容电压。通过仿真计算,验证了理论分析的正确性,并且指出了当特征阻抗一定时谐振频率应该折中选择,指出了当谐振频率一定时开关频率也应该折中选择,并给出了相关标准。通过利用零电流谐振电源控制芯片UC3867,使功率开关器件实现了真正意义上的零电流关断,从而避免了关断过压的产生,减少了关断过程的损耗。通过采用双段式充电的控制策略,即当负载电容电压小于预设电压的90%时以较高的开关频率充电,当电容电压达到90%以后以较低的开关频率充电,使电容避免了过充的危险。该电源经过测试,达到了预期的各项指标。在对10μF电容充电时,250 ms内充电到了2500 V,并且电压的重复性好。在等离子体负载下可以稳定工作在2.5 Hz,电容器的最大放电电流达到了4 kA。最后对电源的优化设计进行了展望。更多还原

【Abstract】 For pulsed power systems utilizing capacitors as the energy storage unit, the performance of capacitor charging power supplies (CCPS) determines the stability and repeatability of the output voltage. High frequency resonant converters exhibit many advantages when used for capacitor charging, and one kind of them, series resonant converter (SRC), is employed universally to charge large-capacity capacitors.This paper presents the research and development work on series resonant CCPS applied to pulsed plasma thruster (PPT). By steady state analysis of resonant circuits working in discontinuous current mode in series resonant CCPS, three functional relationships between peak value of resonant current, peak value of resonant voltage, voltage on load capacitor and numbers of resonant periods are found and the inherent constant-current characteristic, which disappears as the current through anti-parallel diodes declines to zero, are demonstrated. Furthermore, the precise time when the constant-current characteristic changes and the voltage on the load capacitor at that moment are calculated. The truth of theoretical analysis is testified by circuit simulation. The suggestions on how to choose suitable resonant frequency when circuit characteristic impedance is known and how to choose suitable operation frequency when resonant frequency is known are made. The power switch apparatus in CCPS experience‘true’zero current switching (ZCS) process by utilizing zero current resonant mode power supply controller UC3867 and thus the danger of turn-off overvoltage facing switch apparatus is avoided while the power dissipation in turn-off period is reduced. The dual-mode charging control scheme which means CCPS operates in high frequency before the charging voltage on load capacitor reaches 90% of the target voltage and operates in low frequency after that reaches reduces the possibility of over charging on the load capacitor.The system is tested and anticipated results are got. A load capacitor of 10μF is charged to 2500 V linearly within 250 ms and the repeatability of output voltage is acceptable. The repeated frequency of CCPS is 2.5 Hz when the load capacitor discharges to plasma. Some possible improvements are also proposed in the paper.更多还原