MODEL AND SIMULATION FOR A BRUSHLESS AC GENERATOR WITH A ROTARY RECTIFIER

Objective For a brushless AC generator with a rotary rectifier, it is necessary and significant to model and simulate at normal and fault operation states. Methods Two new concepts, namely, Simulink signals and PSB(Power System Blockset) variables, are proposed, and the difference between the two concepts is clarified. Based on the new model for synchronous machines \, a simulation model for a brushless AC generator with a rotary rectifier is constructed by Matlab/Simulink/PSB. This new model, which has a speed input terminal and an exciting voltage input one, can simulate the real electrical characters and direct mechanical connection between two synchronous machines perfectly. The rotary rectifier is a three-phase full-wave bridge rectifier which consists of six diodes. The model for the diodes is a macro-model which possesses much better accuracy than an ideal one of switches. Results Based on the present model, some simulation results such as exciting current waveform, phase current waveform and phase voltbge waveform are afftained at several operation conditions. Conclusion The simulation for a brushless AC generator with a rotary rectifier is demonstrated at normal and fault operation states, respectively. The results confirm the presented method.

Online Field Current Estimation for Brushless Synchronous Starter/Generator Considering the Rectifier Commutation Mode

The information of the field current is essential for the brushless synchronous starter/generator system,which determines the performance and health status of this system.However,since the field winding of the main machine is installed in the rotor part,the measurement of the field current in this brushless system seem impossible.Considering that,the field current might be affected by the rectifier mode,the field current estimation method in different rectifier mode is studied in this paper.The main exciter(ME)rotor currents were restructured based on the ME flux equations.With these restructured rotor currents,the field current in different rectifier commutation mode is analyzed,then the field current estimation method considering the rectifier mode can be obtained.The experiments in different rectifier modes are carried out to verify the proposed method.

Design of High-voltage Electrostatic Generator Based on STM32

This paper intreduced a high-precision high-voltage elec- trostatic generator which utilized STM32F103 as the main coutroller. The hardware and software design of the system were detailed. The full use of ample on-chip resources of STM32F103, such as ADC and the PWM output of timer, contributed to the small size and low cost of the system. The 16-bit PWM signals, generated by the timer on chip, served to adjust the our-put voltage accurately. The tot~ screen was responsible for the setting and display of output voltage, and the friendly humawcomptaer interaction was built. Experimental results indicated that this high-voltage static generator was of high precision and great practicability for application.

Predictive direct power control of three-phase PWM rectifier based on TOGI grid voltage sensor free algorithm

In predictive direct power control(PDPC)system of three-phase pulse width modulation(PWM)rectifier,grid voltage sensor makes the whole system more complex and costly.Therefore,third-order generalized integrator(TOGI)is used to generate orthogonal signals with the same frequency to estimate the grid voltage.In addition,in view of the deviation between actual and reference power in the three-phase PWM rectifier traditional PDPC strategy,a power correction link is designed to correct the power reference value.The grid voltage sensor free algorithm based on TOGI and the corrected PDPC strategy are applied to three-phase PWM rectifier and simulated on the simulation platform.Simulation results show that the proposed method can effectively eliminate the power tracking deviation and the grid voltage.The effectiveness of the proposed method is verified by comparing the simulation results.

Experimental Studies of the Effect of Electrolyte Strength, Voltage and Time on the Production of Brown’s (HHO) Gas Using Oxyhydrogen Generator

A great challenge in water electrolysis is how to optimize the major factors that influence the production of hydrogen gas. Over the past years, different methods have been used to produce hydrogen gas from carbon-base fossil fuels but these methods have been proven to be environmentally unfriendly due to the enormous release of greenhouse gases associated with their use. In this work, an experimental study was carried out to evaluate the effect of electrolyte strength, voltage and time on the volume of HHO gas produced using a design built HHO gas generator. The generator was constructed from Stainless Steel 316 L plates made of 3 anodes, 3 cathodes, and 20 neutral plates. During the study, the strengths of KOH, NaOH, and NaHCO3 was prepared within the range of 0.010 M - 0.030 M. The prepared strengths for each catalyst were then varied across voltage range of 9 V to 13 V for 50 seconds. The experimental results obtained showed that, increasing electrolyte strength, voltage and time proportionally increased the yield of HHO gas. An optimal yield rate of 2.27 cm3/s of HHO gas was obtained when the generator was run at 13 V using 0.025 M KOH. In addition, other factors studied including electrode surface morphology, plate’s configuration, and temperature also showed improvement in yield of HHO gas by 41.85%, 69.74%, and 71.96% respectively.

Single-phase Three-level Rectifier with High Power Factor

Based on a neutral point diode clamped eight-switch configuration, a general mathematical model of single phase bi-directional three-level (TL) rectifiers is built by proposing two equivalent TL arms for topology derivation. A series of TL rectifiers are derived by using double TL and multi TL methods, and their characteristics are compared at the same time. A novel seven-switch double TL rectifier is constructed, and its operational principle and control algorithm are illustrated as well. Lastly, its waveform and harmonic spectrum are compared to those of multi TL rectifiers, and the adopted rectifier gains better performance and unit PF.

Research on dual-stator winding multi-phase high-speed induction generator with rectifier load

Based on analysis and calculation of the relation between current harmonics and MMF harmonics in the dual-stator winding multi-phase high-speed induction gen-erator with a rectifier load, a new idea, which divides the generator system into two sub-systems to be analyzed individually, is presented. For the sub-system of the 12-phase power winding with a rectifier load, the loop current method is used to establish network equation set in terms of the network graph theory. The numerical stability problem is solved by alternating use of fixed time-step and varied time-step, and the voltage and current with their fundamental components of the power winding are obtained. For the other sub-system of the induction generator with dual-stator winding and solid cage rotor, the electromagnetic field analysis method and the multi-variable optimization approach are combined to get the con-trol winding current and stator frequency. Calculated results well match experiment results, indicating that the new proposed method is of effectiveness and high ac-curacy.

考虑原动机调速特性的中压直流发电机组动态仿真模型

鉴于原动机调速特性对舰船中压直流(MVDC)发电机组运行影响的重要性,该文基于十二相同步发电机及其三相交流励磁机数学模型提出MVDC发电机组动态建模方法,以解决多相整流发电机及其励磁系统难以考虑原动机动态调速特性的难题。以某型燃气轮机整流发电机组动态仿真模型为基础,建立了频率不同的十二相同步发电机与三相交流励磁机组合模型,阐述原动机调速与发电机励磁调压相互耦合的计算流程。实测与仿真结果表明,该型燃气轮机发电机组在突加20%负载工况时转速跌落较大,且转速恢复过程需约20 s,但MVDC发电机组通过调节励磁系统可在1 s内使直流母线电压恢复稳定,从而为负载提供稳定直流功率输出。在校准仿真模型的基础上,通过系统分析突加不同比例负载时的转速、燃油流量、励磁电流、输出电压等性能参数变化规律,获取了燃发机组允许突加负载上限约为30%的运行边界认知,为MVDC发电机组励磁系统设计以及如何预留充足的短时强励能力提供了理论支撑。

深海洋流发电系统的PWM整流策略设计

洋流能是一种环保的清洁可再生能源,要实现洋流能的开发利用,离不开发电设备的研究。同时也能解决深海各种传感器水下长期供电的问题,优化当前采用的锂电池供电方式,减少锂电池的更换,节省人力物力,所以,设计一种利用深海洋流能发电的系统具有十分重要的意义。在深海洋流发电系统中,这里针对洋流发电机脉宽调制(PWM)整流器提出使用模型预测直接功率控制策略替代传统电压电流双闭环的控制策略,实现发电机的单位功率因数运行,不仅提高了深海发电系统的稳定性,而且提高了发电机的运行效率,从而提高了洋流能的转换效率。

改进的单相三电平PWM整流器中点电位平衡模型预测控制

针对单相三电平脉冲整流器存在中点电位不平衡问题,提出一种评价函数,在模型预测算法的基础上增加了一个评价因子,在无需额外的中点电位平衡模块条件下实现了单相三电平脉冲整流器中点电位平衡。为降低硬件设计成本,提高电路可靠性,采用无网压传感器算法,但传统的无网压传感器会因引入一阶低通滤波器而产生相位偏移和幅值衰减的问题;为解决相位和幅值问题,提出一种改进的无网压传感器算法,利用α-β的垂直关系进行幅值和相位补偿,得到无相位偏移和幅值衰减的网侧交流电压。通过实验验证了所提控制方法的正确性和有效性。

倍压整流型LCC谐振变换器轨迹控制启动策略

倍压整流型LCC谐振变换器兼顾了串联和并联谐振变换器的优点,具有高电压增益、抗负载短路、兼容变压器寄生参数等能力,已成为医用X光机高压发生器的优选拓扑。然而,倍压整流器中的电容参与谐振,增加了谐振元件数量,导致变换器的动态特性更复杂,进而对建模和控制提出更高的要求。传统的基波近似法和线性控制难以实现精确建模并跟踪控制指标。对此本文采用状态平面分析法,通过分析变换器的工作原理建立各模态归一化状态轨迹方程。在此基础上,提出一种状态轨迹控制启动策略,通过设置谐振电流限幅值,根据输出电压变化规划最优路径,使状态变量在最短时间内跟踪谐振腔最优轨迹,以此计算最佳开关频率。最后,在50 kW/140 kV的样机上验证所提建模方法的准确性和控制策略有效性。实验结果表明,所提方法有效提升了启动速度,实现了不同电压等级之间的快速切换,抑制了谐振腔电流、电压过冲。

基于电流位置关系的DSEG整流器开路故障诊断算法

整流器作为电励磁双凸极发电机(DSEG)的重要组件,其承受频繁的高压和大电流,容易产生故障。然而由于DSEG相电流的不对称性和非正弦性,传统的故障诊断算法在变工况的暂态极易出现误检测。为了诊断DSEG整流单元的开路故障,提出了一种基于相电流大小位置关系的强鲁棒性诊断策略。理论推导和试验验证表明,所提出的强鲁棒性开路故障诊断策略在变负载、变励磁和变转速的暂态不会出现误诊断,并且可以在一个基波周期内检测出所有类型的单管和双管开路故障,计算量小,占用空间小。

脉冲负载下十二相整流发电机瞬态电压调整率解析

十二相整流发电机集直流电压脉动小、动态性能佳等诸多优点为一体,成为舰船综合电力系统中大功率供电模块的理想选择,但由于模型阶次高且整流系统运行模式复杂,导致脉冲负载作用下直流侧最大瞬态电压调整率解析计算困难。为此,对十二相同步发电机进行等效降阶处理,同时利用功率等效原则将直流侧负载折算到交流侧,建立起十二相整流同步发电机的等效三相同步电机模型。基于此给出十二相整流发电机在矩形波脉冲负载下直流侧最大瞬态电压调整率的解析计算方法,并通过时域仿真和物理试验验证了提出计算方法的有效性。

Reliability Analysis of Excavator Rectifier Feedback System with Multi-State Components Based on Belief Universal Generating Function Method

In view of the complexity and uncertainty of system, both the state performances and state probabilities of multi-state components can be expressed by interval numbers. The belief function theory is used to characterize the uncertainty caused by various factors. A modified Markov model is proposed to obtain the state probabilities of components at any given moment and subsequently the mass function is used to represent the precise belief degree of state probabilities. Based on the primary studies of universal generating function(UGF)method, a belief UGF(BUGF) method is utilized to analyze the reliability and the uncertainty of excavator rectifier feedback system. This paper provides an available method to evaluate the reliability of multi-state systems(MSSs) with interval state performances and state probabilities, and also avoid the interval expansion problem.

变速变频交流电机及其供电系统分析研究

本文构建了变速变频交流电机及其供电系统,并验证供电系统模型的有效性。利用Matlab/Simulink构建变速变频发电机、自动变压整流器、发电机断路器的仿真模型,仿真分析不同频率下电机的电压、电流特性,以及自动变压整流器、变压整流器、自动变压器等二次元件的特性,仿真结果表明所建立的供电系统模型能较好的反映变速变频电机及供电系统特性,准确性与有效性满足变频交流电的供电需求,为实际工程应用奠定良好的理论基础。

今、帛、竹书《周易·蛊》卦爻辞本义考论

《蛊》之卦名即意为“蛊乱”,《易》学史上的“拯弊治乱”说、“从事”说、“侍奉父母”说、“筮占事业”说均非其本义。卦辞“元亨”即大为亨通,而非享祀之义,“先甲三日,后甲三日”与祭祀、天气预报或侍奉父母无关,而是含有“殷鉴不远”的意味。初六“有子考无咎”之“考”并非“成就”,而是指父亲,九二“干母之蛊”、九三“干父之蛊”皆与继承父辈、母辈画卦事业无关,二爻本义均与整治蛊乱相关。六四“裕父之蛊”旨在批判君王宽裕治蛊的行为,杨万里将之视为正确的治蛊措施是不恰当的。六五“用誉”之“誉”并非指九二,应意为“荣誉”。上九似当依帛书本作“不事王侯,高尚其事,凶”,其义理体现出君王应将“治蛊”事业进行到底的哲理。

交流发电机整流系统传导电磁干扰的时域模型与仿真分析

该文针对交流发电机整流系统的传导电磁干扰进行时域仿真研究。对一实际系统进行了实验测试,基于传导EMI产生机理的分析,建立了可对系统传导EMI进行仿真研究的时域模型,并且考虑了系统中高频段不可忽视的寄生参数的影响。通过把每相绕组分成数阶相同的p 型电路来描述电机绕组的分布寄生参数,给出了提取电机高频模型中分布参数的一种方法。把系统简化为由主要寄生参数组成的谐振电路,利用MATLAB软件对实际系统的传导 电磁干扰进行时域仿真研究,通过实验和仿真结果的对比验证了模型的正确性。

柴油发电机组-脉冲负载系统运行行为仿真

柴油发电机组-整流器供电系统是重要的移动装备电源形式,可作为重要工程的备用电源,也可作为直流微电网的重要支撑电源。脉冲负载集成了大量电力电子器件,是一类功率波动明显且切换频繁的负载形式,以含大功率收发组件的数字式雷达为代表。在脉冲负载工作过程中,线路中电流与电压呈强烈非线性,系统动态过程复杂,难以运用解析方法表示柴油发电机组内部的机电过渡过程与电磁暂态。文中建立了基于Matlab/Simulink的系统模型,分析了脉冲负载在不同工作模式时,柴油发电机组输出电压与频率的瞬态和稳态指标,结果表明:该模型能够较真实地反映柴油发电机组-整流器-脉冲负载系统的运行行为。

十二相整流发电机二极管开路的故障运行分析

为研究十二相整流同步发电机在整流元件故障工况下的运行性能,针对不可控整流桥提出了适用于故障情况的二极管通断判别方法。基于电路拓扑理论建立了十二相整流同步发电机系统模型,对单个二极管开路的故障工况进行分析,表明单个二极管开路对直流侧供电品质产生影响,并能得出直流电压与负载大小的数值关系。通过样机仿真结果与试验结果的对比分析,证明了所提分析方法的有效性,为判断多相整流同步发电机二极管开路故障时容错运行的可行性提供理论依据与实用措施。

改进型变步长最大功率跟踪算法在风力发电系统中的应用

为了改善永磁直驱式风力发电系统最大功率跟踪算法的稳态跟踪准确度和动态跟踪速度,提出了一种改进型变步长爬山搜索寻优算法;它结合同步电机矢量控制技术,在同步旋转坐标系下,通过解耦控制电机交轴电流分量,达到对风力机转速的控制。变步长最大功率跟踪算法思路是:基于两点斜率比较,判断发电系统接近最大功率点,通过指数衰减步长抑制发电系统在最大功率点附近振荡;不依赖风速传感器,通过每个寻优周期动态设置风速突变检测阈值,准确辨识风速变化,并重新初始化步长提高对风速变化的快速跟踪性能。通过搭建风力发电系统的Matlab/Simulink仿真模型和硬件实验平台,验证了该算法的有效性,展示了其良好的工程应用价值。