CRM Buck PFC变换器的变导通时间控制研究

发布时间：2018-10-31 15:59

【摘要】：在生产和生活中,电力电子设备的供电绝大多数是直流电,而电网的供电通常是交流电,所以要进行交流-直流变换。最早的电容滤波不可控桥式整流电路,交流输入侧电流波形畸变比较严重,含有比较多的谐波成分,需要功率因数校正技术来减小谐波,提高功率因数。Buck PFC变换器工作在CRM模式时,其开关管工作频率在工频内随输入电压的变化是变化的,且变化频率范围比较大,由此带来的开关损耗比较大,还会产生EMI等不良影响。针对传统峰值电流控制的方法,提出一种变导通时间控制策略。在峰值电流参考信号中注入一定量的三次谐波,实现工频周期内导通时间和关断时间以及开关周期都是变的。找到最优的三次谐波量,降低变换器的最大开关频率,使开关频率范围最小,增强变换器的应用性能。AC-DC变换的Buck拓扑自身存在一个缺陷,当输入电压小于输出电压时,变换器不工作,输入电流有部分死区,致使功率因数不如其他拓扑高。针对传统定导通时间的控制方法,提出一种变导通时间控制策略。在峰值电流参考信号中注入一定的反相三次谐波,抵消原先的含量,得到能使PF最大时的三次谐波函数和导通时间函数,设计电路实现控制过程。减少其谐波含量,提高功率因数,优化其他性能,增强其工程应用。最后,为了验证理论分析的有效性,本文进行了实验验证。选定实验参数,研制了变导通时间控制优化CRM Buck PFC变换器的开关频率和变导通时间控制提高CRM Buck PFC变换器的功率因数的原理样机。分别给出了不同输入电压下的实验波形,实验数据和结果分析验证了理论分析的有效性。
[Abstract]:In production and daily life, the power supply of power electronic equipment is mostly direct current, while the power supply of power grid is usually alternating current, so it is necessary to carry on AC-DC conversion. The earliest capacitive filter uncontrollable bridge rectifier circuit, AC input side current waveform distortion is serious, contains more harmonic components, the need for power factor correction technology to reduce harmonic, When the power factor. Buck PFC converter works in CRM mode, the switching frequency varies with the input voltage in the power frequency, and the frequency range is relatively large, resulting in a large switching loss. Also can produce EMI and other adverse effects. In view of the traditional peak current control method, a variable conduction time control strategy is proposed. A certain amount of third harmonic is injected into the peak current reference signal, and the on-on time, turn-off time and switching period are all changed in the power frequency cycle. Find the optimal third harmonic, reduce the maximum switching frequency of the converter, minimize the switching frequency range, enhance the performance of the converter. The Buck topology of AC-DC transform has a defect, when the input voltage is less than the output voltage, The converter does not work, and the input current has a partial dead zone, which causes the power factor to be lower than other topologies. A variable conduction time control strategy is proposed for the traditional control method of fixed conduction time. A certain inverse third harmonic is injected into the peak current reference signal to cancel the original content. The third harmonic function and the conduction time function can be obtained when the PF is maximum. The control process of the circuit is designed. Reduce its harmonic content, improve power factor, optimize other performance, enhance its engineering application. Finally, in order to verify the validity of the theoretical analysis, this paper carried out experimental verification. Based on the experimental parameters, a prototype is developed to improve the power factor of CRM Buck PFC converter by changing the switching frequency and changing the on-time control of the CRM Buck PFC converter. The experimental waveforms under different input voltages are given, and the experimental data and results show the validity of the theoretical analysis.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM46

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