原边反馈反激变换器数字控制环路设计

发布时间：2018-04-22 01:10

本文选题：数字控制 + 原边反馈　；参考：《东南大学》2015年硕士论文

【摘要】：原边反馈反激变换器由于省去了隔离光耦等电路元件,降低了电路复杂度和成本,近年来广泛应用于小功率电源适配器领域。对该类变换器采用数字复合多模式控制可更为灵活有效地实现高平均效率、快速动态响应和高精度等性能,已成为了发展趋势。但是数字复合多模式控制环路还存在采样电路面积大、模式切换不平滑、PFM控制不精确等方面的问题,这也是当今学术界研究热点。本文针对原边反馈反激变换器,给出了一种新型的数字复合多模式环路控制策略,可在全负载范围内实现PWM/PFM/DPWM/DPFM/DDPWM多模式的切换,提高全负载平均效率。本文首先对DCM反激变换器进行环路建模,为数字PI补偿器参数调整提供理论依据。其次设计了一种数字原边采样算法,该算法省去了额外的电路开销,能够节省电路的功耗和面积。接着设计了恒压模块算法,其中重点研究了数字PFM控制和模式间平滑切换技术,能够实现PFM模式下的精确调频和模式之间的低扰动切换,并有助于提高系统的动态响应速度。然后设计了恒流模块算法和谷底导通算法,并提出了一种新型的关断重启电路,可有效地对电路提供保护。最后在5V/1A的AC-DC电源系统上验证了所设计环路控制策略和算法的有效性。测试结果表明：本设计在全负载范围内恒压精度达到±1%；恒流精度达到±4.8%；满载和空载之间动态切换时的最大峰峰值为1.28V；系统在全负载范围的平均效率达到79.26%：谷底导通算法能够使系统效率提高0.5%以上；模式之间实现了平滑切换；保护算法功能正常。测试结果满足了设计指标要求。
[Abstract]:The original side feedback flyback converter is widely used in the field of small power supply adapters in recent years because of the elimination of isolated optical coupling and other circuit elements which reduce the complexity and cost of the circuit. It has become a trend to adopt digital compound multimode control to achieve high average efficiency, fast dynamic response and high precision. However, there are still some problems in the digital composite multi-mode control loop, such as large sampling circuit area, uneven mode switching and imprecise PFM control, which is also a hot research topic in academic circles. In this paper, a novel digital compound multimode loop control strategy is proposed for the original side feedback flyback converter, which can realize the multi-mode switching of PWM/PFM/DPWM/DPFM/DDPWM in the full load range and improve the average efficiency of the full load. In this paper, the loop model of DCM flyback converter is established firstly, which provides theoretical basis for parameter adjustment of digital Pi compensator. Secondly, a digital original edge sampling algorithm is designed, which saves the extra circuit overhead and saves the power consumption and area of the circuit. Then, the algorithm of constant voltage module is designed, in which digital PFM control and smooth switching between modes are studied, which can realize the precise frequency modulation in PFM mode and the low disturbance switching between modes, and help to improve the dynamic response speed of the system. Then the algorithm of constant current module and bottom conduction algorithm are designed, and a new turn-off restart circuit is proposed, which can effectively protect the circuit. Finally, the effectiveness of the proposed loop control strategy and algorithm is verified on the AC-DC power supply system of 5V/1A. The test results show that the design has constant voltage accuracy of 卤1, constant current accuracy of 卤4.8, maximum peak value of 1.28 V when switching between full load and no load, and the average efficiency of the system in the full load range is 79.26. The general algorithm can improve the efficiency of the system by more than 0.5%. Smooth switching is realized between modes and the function of the protection algorithm is normal. The test results meet the design requirements.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM46

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