【作者】 王成智；

【导师】 邹云屏；

【作者基本信息】 华中科技大学 ， 电气工程， 2008， 博士

【摘要】 随着经济的发展,各种电源被广泛应用于人们生产、生活的各个方面,电源的优劣将直接影响生产、生活,因此需要对其进行严格的考核。传统的电源考核方式带电阻、电感、电容等元器件,不仅大量的能量被无谓地消耗掉,同时需要耗费大量的人力、物力对其进行管理,因此本文提出了采用电力电子器件构成的电力电子负载对其进行测试,它可以根据实际需要对电流幅值、功率因数、波峰因数等参数进行灵活设定,同时将测试电能高效地馈回电网,既方便又节能,是一种高效的测试方式。本文针对其与小功率电路级测试设备“电子负载”概念上易于混淆的问题,给出了电力电子负载的定义,它是由大功率电力电子元件构成,利用电力电子控制技术对各种电源设备进行节能、环保考核的电源测试设备。文章给出了它应用于不同测试场合如直流电源测试、三相交流电压测试等不同场合测试时控制和接线方式,并分析了电力电子负载对交、直流纯阻、阻感、阻容模拟原理,给出非线性负荷电路方程并建立数学模型以利于对其实现准确模拟,针对不同工作模式,如恒阻、恒流、恒功率等不同应用场合,给出它们的指令设定方法;并根据系统要求给出了主要元件交流电感、直流电容的选取方法。文章从电力电子负载的基本构成单元单相整流器的控制入手,建立了系统整体数学模型。针对P和PI控制器构建了控制系统,根据离散控制系统Jury判据,给出了控制器参数设定范围,并采用常用的典型Ⅰ型系统和典型Ⅱ型系统最佳整定方法对控制器进行设计,采用动态系数法对PI系统的误差进行了分析和计算,对采样回路中常被忽视的电路滤波器对系统的影响以及设定规则也进行了分析。针对传统PI控制器带宽有限,无法同时满足系统鲁棒性和精度要求的缺点选用了P控制器与重复控制器并联的改进重复控制器结构,它使电流内环获得“零误差”的良好跟踪特性,重复控制器具有足够的频带宽度,完全满足对非线性负荷模拟的需要,同时也保证了馈网电能质量。按照比例控制器、串联校正滤波器S₁（z）、串联低通滤波器S₂（z）、相位补偿环节z^K、重复控制器增益Kr的步骤给出了改进重复控制器设计方法。从电力电子负载电路功率平衡方程入手,根据电力电子负载工况分为多种情况,分析直流电压谐波幅值和频率分布范围,为滤波器的设计奠定了基础。选择陷波滤波器、低通滤波器和均值滤波器进行比较分析,给出了它们的设计和实现方法;为保证系统的稳态控制效果,最终选用均值滤波器,并指出其动态特性的不足需要其它控制方法予以弥补。文章对滤波器在控制系统中的放置位置也进行了探讨。最终,忽略电流内环小惯性环节,将系统等效为一个典型Ⅱ型系统,采用最佳整定法完成了控制系统设计。选用了前馈+反馈的复合控制方法,采用瞬时功率平衡方程和有功功率平衡方程建立了小信号控制模型,并以此为基础建立了复合控制系统,有效抑制了输入电压、电网电压扰动和输入电流指令变化对系统的影响,提高了系统动态特性;同时分析了在电流环中电压前馈控制有效抑制电压扰动的机理和设计方法。为验证以上控制方法,搭建了功能较齐全的10kVA电力电子负载样机,经测试完全达到设计要求,设备运行稳定、可靠;为工业应用奠定了扎实的基础。更多还原

【Abstract】 With the development of economy, all kinds of power sources have been applied in every respect of production and people’s daily life, their qualities are very important, so the stern tests for them are essential. A great number of components , such as resistances, inductances and capacitors which are used in traditional tests, not only waste a lot of test energy, but also take a lot of time for workers to fix and modulate the test circuit. The paper presents a novel equipment named PEL（Power Electronics Load） to test power source, thus the current values, power factor, creast factor and other parameters can be flexibly set to fulfill various tests, and the test energy can be fed back to the grid with little loss , high power factor and low current THD（Totle Harmonic Distortion）.In view of the phenomenon that people sometimes confuse the equipment with another apparatus which are used to test the circuit board, the thesis gives the definition of PEL, which is a kind of equipment constructed by the power electronics components and controlled by the control theory of power electronic. Besides, PEL is used to test various power sources with little power loss by recycling the test power.The thesis presents the control strategy and electric circuit to test the DC power source or three-phase AC power source, and analyzes how PEL simulate all kinds of linear or nonlinear loads. The methods used to set the current reference in CCM （Constant Current Mode）, CRM （Constant Resistance Mode） and CPM （Constant Power Mode） are introduced, effective ways for calculating and selecting the main circuit elements such as ac inductance and dc capacitor are discussed.The mathematic model is constructed from the circuits, P（Proportion） or PI （Proportion and Integral） control is firstly applied to simplify the design process. Jury test in control theory is used to analyze the stability of the whole system; dynamic parameter method in control theory is used to discuss the steady-state errors of the current loop. The effect and parameters selection of the low-pass filter in the current sampling circuits are discussed.Traditional PI controller can not track the current reference very closely and the band width of the close system is limited, especially in medium or high frequency band, the PI controller will cause great steady state error. For one thing, the improved repetitive controller with P and repetitive controller in parallel connection are proposed. The system with enough band width tracks the nonlinear current reference with nearly zero steady state error; for another thing, it ensures the quality of the recycling current of the grid connection converter. The design process of the controller from P controller, cascade compensation link S₁（z）, cascade low-pass filter S₂（z）, phase compensation link z^K, to the repetitive gain Kr, is presented.Spectral analysis of DC link voltage ripple in various work modes is provided to design the filters in the DC voltage control loop. The design and realization processes of digital notch filter, low -pass filter and mean filter are presented, and their characteristics are analyzed and compared. The mean filter, due to its best quality of eliminating harmonics, is applied in the controller; the thesis also indicates that the mean filter will deteriorate the dynamic characteristics of the whole system, other control methods should be added in. The effects of the filter’s location in the controller are also discussed. Finally the engineering design method of dc voltage control loop is presented.According to the instantaneous power and active power balance, the small signal model of the whole system is constructed. The feedforward control of the input active current reference, ac voltage can eliminate the bad effects of the fluctuations caused by the ac voltage or power flow; it optimizes the steady-state and dynamic state characteristics of the whole system.A 10kWA power electronics load prototype is constructed to testify the whole design and analysis of the thesis. The multifunction equipment under comprehensive protection operates well and stably, which fully demonstrates the fact that PEL can be widely applied in various power sources’ tests.更多还原