连续模式单级PFC反激式变换器的研究与设计

发布时间：2018-09-04 13:51

【摘要】：随着相关规范的日趋严格,开关电源的设计面临着越来越多的挑战。其中关于对功率因数(PF)或者谐波含量的强制要求随着设备功率的不断增大开始不断普及。功率因数校正(PFC)技术能够提高线路中电流的利用率,同时显著地降低了电流中的谐波分量,提高了用电设备的功率因数。单级PFC反激式变换器在目前有较为广泛的应用,目前市场上的相关结构包括以下两种:第一种是临界模式单级PFC反激式变换器,这类结构通常采用的峰值电流控制模式,电路结构和复杂度与普通反激式变换器基本一致,电路成本非常低。由于系统工作在临界模式,电感及开关管峰值电流较大,比较适合小功率下的应用。第二种是连续模式单级PFC反激式变换器,这类结构通常采用平均电流控制模式,比较适合中等功率(100W左右)的应用。但这种结构的控制方式较为复杂,电路成本较高,并且需要专门的控制IC。本文提出了第三种模式的单级PFC反激式变换器兼具了以上两种变换器的优点,这种控制模式使用固定的开关管关断时间,在实现连续模式的前提下,允许系统采用简单廉价的峰值电流控制模式。相对于断续工作模式,这种结构有效降低了开关管、次级输出二极管以及电感的峰值电流,缓解了前级EMI滤波器承受的高次谐波电流应力,同时相对于平均电流控制模式而言,这种结构不需要专门的控制芯片,电路结构较为简单,成本相对低廉。本文在对临界模式和连续模式两种情况进行了对比,完成了固定关断时间控制模式单级PFC反激式变换器大信号建模,同时设计了系统电路,通过仿真验证了该结构的可行性,最后设计制作了样机,通过样机实测对理论进行验证。
[Abstract]:With the increasingly stringent standards, the design of switching power supply is facing more and more challenges. The mandatory requirement of power factor (PF) or harmonic content becomes more and more popular with the increasing of equipment power. The power factor correction (PFC) technique can improve the utilization rate of the current in the line, reduce the harmonic component of the current, and improve the power factor of the electric equipment. Single-stage PFC flyback converters are widely used at present. At present, the related structures in the market include the following two types: the first is critical mode single-stage PFC flyback converters, which are usually used in peak current control mode. The structure and complexity of the circuit are basically the same as those of the common flyback converter, and the cost of the circuit is very low. Because the system works in critical mode, the peak current of inductor and switch is large, so it is more suitable for low power applications. The second one is continuous mode single-stage PFC flyback converter. This kind of structure usually adopts average current control mode and is more suitable for medium power (about 100W). However, the control mode of this structure is more complex, the circuit cost is high, and special control IC. is needed. In this paper, a third type of single-stage PFC flyback converter is proposed, which has the advantages of the two converters mentioned above. This control mode uses a fixed switch off time and realizes the continuous mode. Allows the system to use a simple and inexpensive peak current control mode. Compared with the intermittent mode, this structure can effectively reduce the peak current of the switch, secondary output diode and inductor, alleviate the high harmonic current stress of the former EMI filter, and compare with the average current control mode, at the same time, compared with the average current control mode, this structure can reduce the peak current of the switch tube, the secondary output diode and the inductor. This kind of structure does not need the special control chip, the circuit structure is relatively simple, the cost is relatively low. In this paper, the critical mode and the continuous mode are compared, and the large signal modeling of the single-stage PFC flyback converter with fixed turn-off time control mode is completed. At the same time, the system circuit is designed, and the feasibility of the structure is verified by simulation. Finally, the prototype is designed and manufactured, and the theory is verified by the prototype.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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