基于数字控制的全桥单级PFC变换器研究

发布时间：2018-05-09 12:40

本文选题：功率因数校正 + 电压尖峰　；参考：《哈尔滨工业大学》2014年硕士论文

【摘要】：电力电子设备前端普遍采用电容滤波型桥式结构，，这会对电网造成谐波污染。有源功率因数校正技术（APFC）是一种提高用电设备功率因数、抑制电力电子设备谐波污染的有效方法。传统的功率因数校正变换器是由模拟控制实现的。随着电力电子设备往小型化、高效率、智能化方向发展，由于数字控制器具有体积小、功耗低、处理数据量大、处理精度高、易于扩展和升级等优点，数字控制的功率因数校正电路也引起了人们的青睐。随着高速、廉价的数字信号处理器的推出，数字控制技术将成为功率因数校正技术领域中的一个重要研究方向。相对于传统的单级PFC变换器，全桥单级PFC在大功率应用场合具有明显优势：输入与输出电气隔离、桥臂不存在直通危险等。但是，由于全桥单级PFC变换器中的变压器一次侧存在漏感，其在开关切换瞬间会在桥臂上产生较大的电压尖峰。为了抑制该电压尖峰，本文提出一种由电感、电容和二极管组成的无源缓冲技术。该缓冲电路中的电容能够有效地吸收变压器原边电压尖峰，并通过与电感谐振，可以将电容上的能量传递给负载，实现能量的有效利用。通过抑制桥臂电压尖峰，可以大大降低开关管的电压应力，提高电路可靠性。与此同时，缓冲电路的采样还可以辅助部分开关管实现零电压开通，有利于提高电路效率。为了解决传统的PFC控制算法运算量大、结构复杂的缺点，论文研究了一种占空比预测的新型控制算法。该算法具有原理简单、运算量小、电流响应快等优点，能够充分发挥数字控制的优势。通过建立占空比与输入电压、输入电流以及输出电压的关系，实现功率因数校正。在理论分析与软件仿真的基础上，搭建了硬件实验平台。实验结果验证了无源缓冲电路对桥臂电压尖峰的抑制效果，同时表明了变换器具有良好的功率因数校正功能。
[Abstract]:The capacitor filter bridge structure is widely used in the front end of power electronic equipment, which will cause harmonic pollution to the power grid. Active Power Factor Correction (APFC) is an effective method to improve power factor of power equipment and restrain harmonic pollution of power electronic equipment. The traditional power factor correction converter is realized by analog control. With the development of power electronic equipment towards miniaturization, high efficiency and intelligence, the digital controller has the advantages of small volume, low power consumption, large amount of data, high processing precision, easy to expand and upgrade, etc. The power factor correction circuit of digital control has also attracted people's favor. With the introduction of high speed and low cost digital signal processor, digital control technology will become an important research direction in the field of power factor correction technology. Compared with the traditional single-stage PFC converter, the full-bridge single-stage PFC has obvious advantages in high-power applications: the input and output electrical isolation, the bridge arm is not directly dangerous, and so on. However, because of the leakage inductance at the primary side of the transformer in the full-bridge single-stage PFC converter, the voltage spike will occur on the bridge arm at the moment of switching. In order to suppress the voltage spike, a passive buffer technique consisting of inductors, capacitors and diodes is proposed. The capacitor in the snubber circuit can absorb the peak of the transformer's primary voltage effectively, and by resonance with the inductor, the energy on the capacitor can be transferred to the load, and the energy can be utilized effectively. By suppressing the voltage spike of the bridge arm, the voltage stress of the switch tube can be greatly reduced and the reliability of the circuit can be improved. At the same time, the sampling of snubber circuit can assist some switches to turn on zero voltage, which is helpful to improve the circuit efficiency. In order to solve the disadvantages of the traditional PFC control algorithm, which has large computation and complex structure, a new control algorithm for duty cycle prediction is studied in this paper. The algorithm has the advantages of simple principle, small computation, fast current response, and can give full play to the advantages of digital control. Power factor correction is realized by establishing the relationship between duty cycle and input voltage, input current and output voltage. On the basis of theoretical analysis and software simulation, a hardware experimental platform is built. The experimental results show that the passive snubber circuit can suppress the voltage spike of the bridge arm and that the converter has good power factor correction (PFC) function.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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