单相高可靠并网逆变器电路拓扑

针对传统桥式并网逆变器存在桥臂功率开关管的直通问题,提出了一族单相高可靠并网逆变器电路拓扑。所提并网逆变器是由高可靠性单元相互组合而成。分析了双极性和单极性调制高可靠并网逆变器的工作原理,归纳出了高可靠并网逆变器的构成原则。以单极性双降压全桥并网逆变器为例进行了仿真验证。比较分析了传统并网逆变器和所提高可靠并网逆变器。分析结果表明：双降压半桥并网逆变器适合110~120 V电网电压场合,而全桥型高可靠并网逆变器适合220~240 V电网电压场合。     

三相逆变桥驱动开关磁阻电机的研究

将三相开关磁阻电动机绕组采用星型连接,用三相逆变桥对其驱动,采用传统的控制方式运行状况不佳.本文根据开关磁阻电动机产生电磁转矩的原理,分析了每相自感和两相互感在电动机运行中产生电磁转矩的情况,根据其变化规律,推导出独特的720°电角度一周期的对称不均匀励磁方式,使磁阻电动机获得了良好的运行效果,解决了传统三相开关磁阻电机与驱动电源连接线过多的问题.本文结合样机,对励磁方式进行了理论分析,并以实验进行验证.     

New generalized topologies of asymmetric modular multilevel inverter based on six-switch H-bridge

In this paper, for high and low numbers of voltage levels, two new generalized multilevel converters are introduced, which comprise a six-switch H-bridge and several switched-source units. Switched-source units consist of bidirectional and unidirectional switches along with a dc voltage source. The two proposed topologies are compared with topologies based on the six-switch H-bridge, conventional H-bridge, and some new topologies regarding the number of switches, dc voltage sources, gate drivers, and per-unit voltage block on switches. The comparison results reveal the superiority of the proposed topology with low number of voltage level (LNL) and proposed topology with high number of voltage level (HNL) regarding the per-unit voltage block and number of elements, respectively. Thus, the proposed topologies lead to reduction cost and weight of system. Furthermore, for high number of levels, HNL topology is more appropriate than LNL topology and vice versa. The performances of the proposed 15-level LNL and 61-level topologies are simulated by MATLAB, and proposed 15-level LNL topology in producing all voltage levels is validated by experimental results.     

Alternate ASDs: evaluation of the converter topologies suited for integrated motor drives

This article investigates alternative three-phase ASD topologies for integrated motor drives by discussing the hardware requirements and comparing their performance, size of magnetics, and efficiency, which in this case is important in order to determine their cooling requirements. It presents possible converter topologies for the next generation of integrated motor drives, which are arranged in three groups. The grid side performance is analyzed by simulations and their losses estimated. Three recommendations are made, while, for a general application ASD with sinusoidal input current, the choice is given by the price of four diodes against a RB-IGBT.     

新型逆变电路有限控制集模型预测控制

针对传统开关函数模型只能描述电路的控制变迁而忽略了电路的条件变迁这一不足,建立了一种新型逆变电路更为精确的混合逻辑动态(mixed logical dynamical,MLD)模型,并将其作为预测模型,研究了航空新型电路的有限控制集模型预测控制(finite control set model predictive control,FCS-MPC)。FCS-MPC充分利用电路的离散特性,通过比较预测电压值和参考电压值的大小,将其差值作为衡量输入量的目标函数,最后选择电路控制集中使目标函数值最小的开关状态作为电路的控制输入,有效地解决了模型预测控制中混合整数二次规划(mixed integer quadratic programming,MIQP)问题的求解。仿真和实验验证了该控制方法具有良好动静态特性,证实了所提方法的有效性。     

Efficient output waveform evaluation of a CMOS inverter based on short‐circuit current prediction

A novel approach for obtaining the output waveform, the propagation delay and the short‐circuit power dissipation of a CMOS inverter is introduced. The output voltage is calculated by solving the circuit differential equation only for the conducting transistor while the effect of the short‐circuit current is considered as an additional charge, which has to be discharged through the conducting transistor causing a shift to the output waveform. The short‐circuit current as well as the corresponding discharging current are accurately predicted as functions of the required time shift of the output waveform. A program has been developed that implements the proposed method and the results prove that a significant speed improvement can be gained with a minor penalty in accuracy. Copyright © 2002 John Wiley & Sons, Ltd.     

单相有源电力滤波器拓扑结构的分析研究

有源电力滤波器（APF）是现今治理谐波效果最好的补偿装置之一,但由于成本高,难于得到广泛应用。本文在对常规拓扑结构的有源电力滤波器的分析基础上,提出了两种新的拓扑结构———单桥臂带直流电容与不带直流电容拓扑结构,同时提出简单的控制策略。MATLAB仿真研究表明,单桥臂带直流电容拓扑结构的有源滤波器综合效果优于其他两种有源滤波器,该滤波器结构简单、成本低、易于推广使用。     

变工况下航空逆变器健康评估方法研究

工况的变化会引起功率变换器电路健康表征参数随之变化,导致无法判断健康表征参数是因电路性能的退化还是因工况的变化引起的。针对该关键问题,以航空逆变器为研究对象,首先采用多评价指标优选模型优选出相关敏感的健康表征参数;然后基于极限学习机建立工况-无故障情况下健康表征参数映射模型;最后基于当前健康表征参数与映射模型输出的健康表征参数之间的相对变化量构建考虑工况条件的电路健康指标,实现不同工况下航空逆变器的健康评估。实验结果表明,该评估方法可以有效减小工况变化对健康指标的影响。在变工况情况下,相比于直接基于欧氏距离构建健康指标的评估方法,平均绝对误差（Mean Absolute Error,MAE）和均方根误差（Root-Mean-Square Error,RMSE）分别降低了64.4%、66.8%。     

三相电压源逆变器内部IGBT模块温度的求解及评估

三相电压源逆变器的工作性能、使用寿命等方面均与其内部绝缘栅双极晶体管(IGBT)模块温度直接相关,故求解及评估该逆变器中IGBT模块的温度对于确保逆变器系统的安全可靠运行具有重要意义。针对现有模型及方法难以求解IGBT模块温度的问题,本文借鉴直接法的思想,提出了一种新的简单实用的IGBT模块温度求解算法。基于拟合及插值算法,推导并建立了IGBT模块功率损耗模型;基于电热比拟理论,探讨并建立了集中参数的IGBT模块等效Cauer传热网络模型,并将传热微分方程差分化;最终,在同一电路仿真器中构建出IGBT模块温度的求解算法。在三相电压源逆变器的算例中,通过与英飞凌IPOSIM的温度计算结果对比,表明本文算法最大误差为3.01%,且温度变化趋势与IPOSIM基本一致,最后利用该算法评估了逆变器在不同负载工况下的IGBT模块温度,所得结果可为合理地进行三相电压源逆变器的散热设计、长期可靠性评估等服务。     

支持向量机的开关磁阻电动机转子位置估计器

用支持向量机回归函数来逼近转子位置角与相磁链、相电流之间存在的非线性关系,通过对离线获取的磁化曲线的学习,得到作为转子位置估计器的支持向量回归估计函数。并将其应用于在线仿真试验中进行验证,取得了比较理想的试验结果,证明了该方法的有效性。     

一种电压型串联谐振逆变电路的仿真分析

为了深入了解且更好地使用电压型逆变电路,对两种电压型逆变电路进行了简要的描述,利用PSPICE软件对两种电路进行了基于实际负载的仿真分析.重点分析传统串联谐振逆变电路与用于负载匹配的串联谐振逆变电路的工作过程,比较它们的优缺点,并给出仿真结果.仿真结果在证明电路能够进行负载匹配的同时也为进一步研究此问题提供了依据.     

Simplified models of a single-phase power electronic inverter for railway power system stability analysis—Development and evaluation

Use of power electronic equipment has increased and introduced new dynamical phenomena in power systems. For example, new electric rail vehicles (locomotives) equipped with modern power electronic traction chains have caused situations of low-frequency power oscillations and instability in single-phase railway power supply systems. This paper presents the development and implementation of an instantaneous value model and simplified fundamental frequency (RMS) models of such an advanced electric rail vehicle in order to investigate their representation of low-frequency dynamics. The dynamical behaviour is studied by use of both time-domain simulations and linear analysis (eigenvalues) and the degree of simplifications regarding controller dynamics and power system dynamics are presented and discussed. An enhanced RMS model is tested in order to account for the impact of fast current dynamics on the low-frequency behaviour. The results show that this enhanced model is corresponding more closely to the instantaneous value model than what can be obtained by the traditional RMS simplifications and indicate that current dynamics should be included in stability studies involving power electronic inverters.     

A study of a single-phase thyristor inverter

The results of studying the switching processes in a single-phase thyristor inverter operating at a low-voltage controlled thyristor rectifier with constant output current are given. Depending on the angle of rectifier voltage regulating, three switching modes are identified and considered. The maximum values of currents and voltages are defined for each of the modes. The waveforms of currents and voltages are given. It is shown that the nature and duration of the inverter switching processes depend strongly on the angle of rectifier regulating, which is especially to be considered when the inverter operates at higher frequencies.     

The comparative evaluation of excellence for student awards

A recurring problem in the award of academic honors is the comparison of the highest grade achieved by students from different groups with different traditions, practices, and evaluation scales. Group averages are not useful because it is the position of the top student that is of interest, not the average; also, the normal distribution cannot be assumed for the upper tail of the distribution, which must be obtained from the data. We find that the upper grades of each group can be modeled very well, permitting the statistical theory of extremes to be used. From the model which we fit to each group separately, we obtain the probability for a top grade at least as high as the one observed, and from this, we obtain the return period which is the expected interval before the return of a similarly high grade. This return period is a common measure which enables top grades from several disparate groups to be compared on the basis of how rare or exceptional they are as members of their own group. The precision of the return period is estimated from the correlation coefficient of the regression model and used to indicate the effectiveness of the decision in a particular case. The method is applied to data from different disciplines at the University of Waterloo, including comparisons among Engineering Departments     

Harmonic experiences with a large load-commutated inverter drive

This paper illustrates the use of a high-pass filter for reducing troublesome harmonic distortion caused by a large load-commutated inverter drive at a large petrochemical plant. Actual field measurement data of the 12.47 kV distribution system of the plant is given to show the harmonic distortion that was causing operational problems. The harmonic system impedance derived from these measurements was used in the development of an accurate harmonic analysis computer model. This harmonic model was then used to evaluate the application of a high-pass filter to reduce harmonic distortion. Actual field measurements were then made after the installation of the high-pass filter to verify the results of the simulations. The tools used for this paper included a harmonic analyzer, an oscilloscope, a harmonic simulation program, and an electromagnetic transient simulation program. The results of this investigation lead to proposed improvements to IEEE Std 519     

Development of a high-efficiency inverter without audible noise

The proposed inverter combines two methods which can significantly decrease the on-state and switching losses. The first method, using a current transformer and a single transistor, makes possible the reduction of the on-state loss to less than one-third of the usual Darlington transistor. The second method, using an auxiliary commutation IGBT in parallel with the transistor, makes possible zero-voltage switching, resulting in no switching loss. To realize higher inverter efficiency, a snubber and its loss recovery circuit are employed. Three-phase inverters were fabricated experimentally to evaluate our idea. Device volume and weight can be decreased to one-third those of a conventional three-phase inverter, and an efficiency of 98.0% from 5 kW to 20 kW is obtained at a switching frequency of 16 kHz. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(1): 62–69, 1997     

An algorithm for controlling a multilevel voltage inverter

A vector algorithm for the control of a multilevel voltage inverter is presented. The algorithm is characterized by high efficiency and does not depend on the number of levels in the inverter; it is of methodical importance for understanding the principles based on which multilevel inverters operate.     

A novel approach for a sinusoidal output inverter

Minimization of the total harmonic distortion (THD) at the output of an inverter is essential to reach the ideal case, i.e. a pure sinusoidal. So far, very intensive studies about this topic have been carried out. In this study, a fully rectified version of a sinusoidal voltage waveform at an utility amplitude and frequency obtained from a well-known buck–boost regulator has been converted to a sinusoidal AC voltage waveform with a simple inverter operation. The purpose of this innovative circuit is to generate an approximate sinusoidal voltage waveform with a quite low THD at the inverter output without invoking the harmonic elimination techniques. Since distortions in the AC link voltage in this circuit fully depend on how well the capacitor current is regulated to its reference, the value of the load current is a critical component in this regulation.