开关变换器多频率控制技术研究

发布时间：2019-06-27 14:27

【摘要】：随着电力电子技术的快速发展,开关电源因具有重量轻、效率高和体积小等诸多优点而得到了越来越广泛的应用,大量电子设备对其供电电源的稳定性、稳压精度、瞬态响应速度等性能提出了越来越高的要求。传统的以电压型控制、电流型控制为代表的脉冲宽度调制(Pulse Width Modulation, PWM)技术成熟、应用广泛,但存在轻载效率低、动态响应速度慢等问题。因此,为提升开关电源的性能,本论文提出并研究了开关变换器多频率(Multi-frequency, MF)控制技术。开关变换器多频率控制技术是通过多个不同频率的控制脉冲的组合,实现对开关变换器输出电压的调节,是一种不同于PWM控制技术、且立足于双频率控制拓展的新颖控制技术。与传统PWM控制相比,该控制技术具有更快的瞬态响应速度和更好的鲁棒性；与双频率(Bi-frequency, BF)控制相比,该控制技术由于更多频率脉冲的设置,具有更宽的负载功率范围、更低的输出电压纹波、更高的轻载效率等优点。首先研究了双频率控制技术的控制原理与特性,在对控制脉冲组合规律、输出电压纹波、瞬态特性和频率特性进行研究的基础上,指出了双频率控制技术用于电感电流断续导电模式(Discontinuous Conduction Mode, DCM)开关变换器存在无法兼顾输出功率范围和输出电压纹波大小、不适用轻载或空载工作的问题,以及用于电感电流连续导电模式(Continuous Conduction Mode, CCM)开关变换器时存在瞬态性能差与输出电压低频波动的问题。本文研究的多频率控制技术在保留双频率控制技术优点的基础上,有效解决了其在应用中存在的问题。分析了多频率控制技术的原理,研究了DCM开关变换器电压型和电流型多频率控制技术,分析了两种控制技术下的稳定性、输出电压波动量、控制脉冲组合方式、输出电压纹波等特性,通过能量迭代模型研究了输出电容电压的运行轨迹,对比研究了两种控制技术的性能差异和相互关系。论文将多频率控制技术进一步拓展应用到CCM开关变换器,在分析其控制原理与特性的基础上,利用能量迭代模型研究了输出电压低频波动的产生机理,并定量研究了输出电容等效串联电阻值大小对低频波动现象的影响。针对多频率控制CCM开关变换器存在的低频波动问题,研究了电感电流伪连续导电模式(PseudoContinuous Conduction Mode, PCCM)开关变换器多频率控制技术和CCM开关变换器峰值电流型固定关断时间多频率控制技术的原理与特性。研究结果表明：两种方式均有效抑制了多频率控制技术应用于CCM开关变换器存在的低频波动现象。建立了电压型双频率控制、电流型双频率控制、电压型多频率控制和电流型多频率控制DCM开关变换器的一维动力学模型及相应的特征值方程,采用分岔图、Lyapunov指数、时域波形、相轨图、频谱图研究了双频率控制和多频率控制DCM开关变换器的非线性动力学特性,研究结果表明：电压型双频率控制DCM Buck变换器存在边界碰撞分岔行为和多周期行为,其周期3行为并不意味着变换器会必然发生混沌行为；与电压型双频率控制相比,负载变化时,电流型双频率控制具有相似的分岔路由和动力学行为；而输入电压变化时,电流型双频率控制表现出截然不同的动力学特性；与电压型双频率控制相比,电压型多频率控制和电流型多频率控制因误差界限电压的不同而表现出自相似现象和混频现象。此外,论文还建立了多频率控制CCM开关变换器的动力学模型,并分析了相应的动力学特性,揭示了电压型多频率控制CCM开关变换器存在低频波动现象；峰值电流型固定关断时间多频率控制CCM开关变换器不存在低频波动现象,而表现出强烈的多周期行为。本论文对各种控制技术的研究均基于Buck变换器,控制技术均通过基于FPGA的数字控制方式实现,所有理论研究结果的正确性均通过软件仿真和电路实验进行了验证。
[Abstract]:With the rapid development of the power electronic technology, the switching power supply has become more and more widely applied because of the advantages of light weight, high efficiency and small volume, The transient response speed and other performances have raised more and more requirements. The conventional pulse-width modulation (PWM) technology, which is represented by voltage-type control and current-type control, is mature and has wide application, but it has the problems of low light load efficiency and slow dynamic response speed. Therefore, in order to improve the performance of the switching power supply, the multi-frequency (MF) control technology of the switching converter is proposed and studied. The multi-frequency control technology of the switching converter is a novel control technology which is different from the PWM control technology and is based on the dual-frequency control expansion, which is a combination of a plurality of control pulses with different frequencies. Compared with the conventional PWM control, the control technology has a faster transient response speed and better robustness; and compared with the control of the bi-frequency (BF), the control technology has a wider load power range and lower output voltage ripple due to the arrangement of more frequency pulses, And the like. The control principle and characteristics of the dual-frequency control technology are first studied. On the basis of the study of the control pulse combination law, the output voltage ripple, the transient characteristic and the frequency characteristic, the two-frequency control technology is used in the discontinuous conduction mode of the inductive current. The DCM converter has the problem that the output power range and the output voltage ripple size cannot be taken into account, the light load or no-load operation is not applicable, and the problem that the transient performance difference and the output voltage low-frequency fluctuation exist in the continuous conduction mode (CCM) switching converter for the inductor current. In this paper, the multi-frequency control technology is used to keep the advantages of the dual-frequency control technology, and the problems existing in the application of the multi-frequency control technology are effectively solved. The principle of the multi-frequency control technology is analyzed, the voltage type and the current type multi-frequency control technology of the DCM switch converter are studied, the stability, the output voltage fluctuation amount, the control pulse combination mode, the output voltage ripple and the like of the two control technologies are analyzed, The running track of the output capacitor voltage is studied by the energy iteration model, and the performance difference and the relation of the two control technologies are compared. In this paper, the multi-frequency control technology is further extended to the CCM switch converter. Based on the analysis of its control principle and characteristics, the generation mechanism of the low-frequency fluctuation of the output voltage is studied by using the energy iteration model. The effect of the equivalent series resistance of the output capacitor on the low-frequency fluctuation is quantitatively studied. The principle and characteristics of the multi-frequency control technology of the pseudo-continuous conduction mode (PCCM), the multi-frequency control technology of the switching converter of the CCM and the multi-frequency control technology of the peak current-type fixed-off time of the CCM are studied for the low-frequency fluctuation problem of the multi-frequency control CCM (CCM) switching converter. The results show that in both ways, the low-frequency fluctuation of the multi-frequency control technology applied to the CCM switching converter is effectively suppressed. A one-dimensional dynamic model of a voltage-type dual-frequency control, a current-type double-frequency control, a voltage-type multi-frequency control and a current-type multi-frequency control DCM switching converter is established, The non-linear dynamic characteristics of the dual-frequency control and multi-frequency controlled DCM (DCM) switching converter are studied in the frequency spectrum. The results show that the voltage-type dual-frequency control (DCM) Buck converter has a boundary collision bifurcation behavior and a multi-cycle behavior. its cycle 3 behavior does not mean that the converter will necessarily have mixed-frequency behavior; in comparison with the voltage-type dual-frequency control, the current-type dual-frequency control has similar sub-branch and dynamic behavior when the load is changed; and when the input voltage is changed, Compared with the voltage-type double-frequency control, the voltage-type multi-frequency control and the current-type multi-frequency control show similar phenomena and mixed phenomena due to the difference of the error limit voltage. In addition, the dynamic model of the multi-frequency control CCM (CCM) switching converter is established, and the corresponding dynamic characteristics are analyzed, and the phenomenon of low-frequency fluctuation of the CCM switch converter with the voltage-type multi-frequency control is revealed. The peak current type fixed-off time multi-frequency control CCM switch converter does not have a low-frequency fluctuation phenomenon, and shows a strong multi-cycle behavior. The research of the control technology is based on the Buck converter, and the control technology is realized by the digital control method based on the FPGA. The correctness of all the theoretical research results is verified by the software simulation and the circuit experiment.
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM46

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