【作者】 王大庆；

【导师】 贲洪奇；

【作者基本信息】 哈尔滨工业大学 ， 电力电子与电力传动， 2013， 博士

【摘要】 功率因数校正(PFC)技术是消除电力电子设备谐波污染、提高输入功率因数的有效方法。单级全桥功率因数校正技术具有结构简单、效率高、高频变压器双端励磁等优点，适用于中大功率领域。目前，单级全桥PFC技术在效率、功率因数校正效果等方面的研究已经相对成熟，但在电路结构方面存在：母线电压尖峰大、高频变压器容易偏磁、启动过程输入电感过流、输出电压纹波较大等问题，影响了单级全桥PFC技术的应用和发展。当前的解决方案往往只针对其中的一个问题，如同时解决多个问题会导致电路复杂程度增加。为此，有必要针对这几种关键技术进行研究，使用简单的电路结构同时解决多个或全部的问题。单级全桥PFC变换器由于变压器存在漏感，在电路换流过程中母线上会产生较大的电压尖峰。将箝位技术应用到单级全桥PFC变换器中，能够解决变压器漏感在换流过程中产生的母线电压尖峰大的问题。研究了基于有源箝位的单级全桥PFC变换器的母线电压尖峰抑制策略，并进行了实验验证。针有源箝位方案的不足提出了基于无源箝位的单级PFC变换器，分析了电路工作原理及母线电压尖峰抑制机理，分析了母线电压尖峰抑制情况并给出了箝位电容的设计方法，最后通过实验验证了理论分析的正确性。单级全桥PFC变换器特有的工作方式导致变压器存在独特的偏磁现象，影响系统正常运行。在分析变压器偏磁机理的基础上，针对偏磁问题提出一种基于死区调节的偏磁抑制策略。借助箝位电路允许在桥臂开关管的工作时序中添加适当死区的特点，在变压器正负励磁时间内添加死区，并通过分别调节正负死区的大小确保变压器伏秒积平衡，从而抑制偏磁。该偏磁抑制策略仅改变了电路的工作时序，具有不影响系统性能、不改变主电路结构、既能使用数字控制又能使用模拟控制实现等优点。分析了关键参数对系统的影响，设计了基于积分复位的控制电路来实现偏磁抑制策略，并通过实验研究验证了偏磁抑制策略的正确性。单级全桥PFC变换器在起动过程中存在输入电感容易过流的问题，影响系统的可靠性。利用箝位电路特点，提出一种Buck启动方法。在不增加电路复杂程度的基础上通过改变开关管的工作时序抑制启动过程中输入电感过流，解决了启动问题。在提出启动方法的基础上详细介绍了启动方法的工作原理，建立了简化模型，分析了启动过程中输入电感电流的变化规律，给出了占空比等关键参数的设计方法，最后通过实验研究验证了启动方法的可行性及关键参数设计的合理性。单级全桥PFC变换器使用一级电路实现功率因数校正及DC/DC变换，导致输出电压存在较大的二倍工频纹波，影响系统输出特性。传统方式通过增大输出滤波电容的容量来降低输出电压纹波，但会导致系统的动态响应变慢。此外，大量使用电解电容会降低系统的功率密度及使用寿命。为降低单级全桥PFC变换器的输出电压纹波，提出一种基于辅助环节的单级PFC变换器的输出电压纹波抑制策略，通过控制辅助环节的输出电流，降低系统的输出电压纹波。分析了辅助环节的输出电流、辅助环节的输出功率等相关参数对输出纹波大小的影响规律。最后进行了实验研究，证明了该控制策略能够在不影响系统的动态响应特性的基础上降低输出电压纹波。更多还原

【Abstract】 Power factor correction (PFC) technique is an effective method for reducingthe harmonic current of power electronic device and increasing the power factor.Single-stage full-bridge PFC technique is preeminent in simple structure and highefficiency, furthermore, its high frequency transformer exciting by double-ended, soit is suitable for medium and high power application. At present, this technique isrelatively mature in the research such as efficiency, power facror and so on.However, there are still some problems limiting the application of this technique incircuit structure, such as large DC-bus voltage spike, magnetic bias of thetransformer, input inductor over current in starting-up process and large outputvoltage ripple. Presently, the solutions to those problems have been proposedalready, but each scheme can solve only one problem, and the circuit structure iscomplex when all the schemes have been used. So, it is necessary to research thosekey techniques and use simple circuit structures solving some or all of the probl emssimultaneously.Because of the exsiting of leakage inductance in the transformer, there is alarge voltage spike on the bus during the circuit commutation process. The problemof voltage spike can be solved with the adoption of clamp technique. Single-stagefull-bridge PFC converter based on active clamp technique is investigated, and thetheoretical analysis is verified by experimental results. According to thedisadvantages of this converter, a novel single-stage PFC converter based on passiveclamptive technique is proposed. Its operational principle and the mechanism ofvoltage spike suppression are analyzed. Finally, the validity of theoretical analysisis proved by experimental results.Because of the special working mechanism and the required power factorcorrection, the magnetic bias of the transformer appears, by which the stability ofthe converter has been influenced. A novel suppressing approach is proposed basedon the analysis of the magnetic bias mechanism. With the help of clamp technique,the dead zone can be appended in the synchronous timing control of switches, andthe voltage-second balance of the transformer can be achieved by the varying of thedead zone. The proposed scheme can solve the problem without increasing thecomplexity of the circuit, while maintaining its original performance, and it isappropriate in both digital and analog control. The influence rules of key parameterare concluded, the circuit based on integrate reset are designed. The feasibility andadvantage of the proposed approach is verified by the experimental results.Over current of the input inductor appears during the starting-up process of this PFC converter, which can reduce the reliability of the whole system. A novel Buckstarting-up scheme is proposed according to the clamp circuit, which made thestarting process smoothly. By changing synchronous timing of the switches, thescheme can solve the problem without increasing the complexity of the circuitry,while maintaining its normal operation and original performance. The process ofstaring-up and the input current are analyzed by using simplified models of theconverter, and the design methods of the key parameters are given. As experimentalproved, over current in the starting process is suppressed, and the theoreticalanalysis is validity.Single-stage full-bridge power factor corrector realizes PFC and DC/DCconversion in one stage circuit, so there is large voltage ripple in the output sidewhose frequency is double of line frequency, the output characteristic of theconverter is influenced. As a conventional method, increasing the output filtercapacitance could reduce the ripple, while the dynamic response can be reduced. Anovel output-voltage-ripple suppression scheme is proposed in the single stage full-bridge PFC converter based on auxiliary part, which can lower the output voltageripple by controlling the output current of auxiliary part. The influence rules of keyparameters are analyzed, such as the output current of auxiliary part and power ofauxiliary part. As the experiment proved, output voltage ripple is suppressedwithout influenceing the dynamic response by using this scheme.更多还原