SVPWM逆变器供电时FSCW-PMSM损耗特性研究

To investigate the effects of time-harmonic current introduced by inverter on lass characteristics of fractional-slot concentrated-winding permanent magnet synchronous machine (FSCW-PMSM) .a method is proposed to analyze the harmonic characteristics of losses of the machine in inverter and FSCW-PMSM combined system. Firstly, the time-and space-harmonic characteristics of lasses considering time-harmonic current are theoretically analyzed. Then.a 10-pole and 12-slot PMSM with three-phase double-layer winding is taken as an example. The field-circuit co-simulation model of the prototype and space vector pulse width modulation (SVPWM) inverter is established. the harmonic characteristics of lasses are calculated under constant torque and constant power speed control. and the causes of each harmonic lass are revealed. The results show that rotor harmonic losses are caused by fundamental current with sub-harmonic.iZ±p slot harmonics. and (/<.±4/’) // ’. {fc±2f)/f timeharmonic current with p, Z±p space harmonics. Stator core harmonic lasses are caused by fundamental magnetic field, magnet harmonic excitation magnetic field and (/. ±4/’) // ’. (/. ±2f)/f time-harmonic current. The conclusions can be applied to the FSCW-PMSMs with other pole-slot combinations. Finally.the proposed method is validated by experiment results. © 2023, Editorial Department of Electric Power Engineering Technology. All rights reserved.     

背景谐波电压环境下的负载谐波电流检测方法

针对现有谐波电流检测方法未考虑公共连接点处谐波电流的耦合现象而导致谐波治理效果不理想的问题,提出了一种有效解决该问题的负载谐波电流检测方法。在分析现有检测方法不足的基础上,借鉴德国DIN40110-2标准分解电流的思想,以谐波电压为基准,依据等效前后负载消耗有功功率不变的原则,定义了谐波等效电导、集总谐波电压和集总谐波有功功率。利用希尔伯特变换对谐波电压进行移相。进而定义了集总谐波无功功率和谐波等效电纳,分解出由背景谐波电压产生的谐波电流。据此,可检测出负载谐波电流,实现背景谐波电压环境下对负载谐波电流的补偿。仿真分析及实测数据验证结果表明：采用所提方法对检测到的谐波电流进行补偿,可有效提高公共连接点的谐波治理效果。     

Source current harmonic analysis of adjustable speed drives under input voltage unbalance and sag conditions

Adjustable Speed Drives (ASDs) have become the primary choice for most new and retrofit precision motor-control applications, offering major improvements in system efficiency. The significant increase in the use of ASDs makes it important to understand the compatibility issues between ASDs and their electrical environment in order to appropriately design the electrical systems. Even though there have been numerous studies addressing ASD effects on power systems, models for predicting the effect of the source voltage sags or unbalance have been limited. This paper is devoted to the analysis of utility-side input current harmonics under input voltage unbalance and sag conditions and the effects of these harmonics on the distribution transformer K-factor for practical ASD systems. The relationships between the unbalanced input voltages, the resulting input current harmonics, the input inductance, and the required transformer K-factor are explored for 5 hp, 100 hp, and 600 hp power distribution systems with ASDs. The results can be used as a design guide for power distribution system design with ASDs. Theoretical derivations are accompanied by both simulations and experimental results to provide verification of key conclusions.     

基于谐波分析法的高速变频电机铁耗计算方法

提出了一种计算非正弦供电时的高速变频电机铁耗的简单而有效的方法。该方法以谐波分析法为基础，能够综合考虑电源谐波、电机铁芯饱和以及集肤效应的影响，具有较高的精度。与有限元法计算结果的比较表明，该方法具有较高的精度。     

Converter-connected distributed generation units with integrated harmonic voltage damping and harmonic current compensation function

The steadily growing share of converter-connected distributed generators, combined with a large amount of nonlinear and unbalanced loads connected to the electric power system, has led to a degraded power quality. Both harmonic voltage and harmonic current distortion may cause many unfavourable effects on the power system. However, the converter-connected distributed generators can be redesigned to have a positive effect on the distortion of the grid voltage. Two different approaches can be discerned. At the one hand, distributed generation units can be controlled to synthesize a resistive load for harmonic voltage components. This approach is called harmonic voltage damping. At the other hand, if the polluting current of an adjacent nonlinear load is measured and added to the control loop, the converter-connected distributed generator is able to compensate all harmonic current components of the nonlinear load. This approach is referred to as harmonic current compensation. In this paper, a control strategy for a converter-connected distributed generator is extended with a harmonic voltage damping function and a harmonic current compensation function. Experimental tests show that the voltage distortion of the grid voltage can be significantly improved.     

基于电容谐波电流抑制的动态电压恢复器控制方法

针对传统双环反馈控制方法在补偿非线性负载电压跌落时存在补偿精度不高和含有谐波的不足之处,在详细分析了非线性负载对动态电压恢复器补偿特性影响的基础上,提出了一种基于电容谐波电流抑制的新型控制方法。在检测出谐波电流后,通过控制动态电压恢复器产生反向谐波电流来抑制电容电流中的谐波成分,进而消除非线性负载对动态电压恢复器的不利影响。仿真和实验结果验证了所提方法能有效解决非线性负载的电压跌落问题。     

基于CVT电容电流的谐波电压测量方法

准确有效地进行谐波电压测量是掌握电网谐波状况、开展谐波治理、提升电能质量水平的重要前提和依据。为解决目前大量在运CVT无法准确测量谐波的问题,提出基于CVT电容电流的谐波电压测量方法。该方法测量流过高压电容和中压电容支路的电流并进行谐波分析,根据电容参数即可方便准确地计算得到高压侧谐波电压。该方法只需对CVT二次回路进行简单改造,在不影响设备运行安全的前提下,实现谐波电压测量。首先给出该方法的基本原理,然后结合仿真计算分析电流测量精度和电容值变化对谐波测量误差的影响,对实际CVT完成了物理试验验证。试验表明：该方法的2~50次谐波电压测量误差均小于2%,满足谐波国家标准的相关要求。     

电容式电压互感器谐波传递特性试验电路研究

电容式电压互感器(Capacitor Voltage Transformer,CVT)在66 k V及以上电网的广泛应用,对其谐波传递特性研究日趋重要。本文运用黑箱理论并结合CVT电气构造特点,搭建一种可以获取CVT谐波传递特性的试验电路。从电容分压器结构和电介质材料角度研究电介质极化与外电场频率关系,确定在50 Hz~25 00 Hz范围内频率变化不影响电容分压器分压比。再整体分析试验电路,建立试验电路网络阻抗模型,仿真不同分压点电压之间关系,并通过试验进行相互验证,论证测量CVT谐波传递特性的试验电路的正确性。为测量CVT谐波传递特性提供科学规范的测量方法,对CVT谐波传递非线性机理深入研究具有重要意义。     

An investigation of voltage instability problems

The authors investigate the voltage stability problem based on singular perturbation theory. Possible voltage instability patterns are classified into four types (I, II-1, II-2S, and II-2D) according to the mechanism causing voltage instability. Several features of each type of instability are studied as well as their analysis methods. Voltage instability tends to begin with type I and then leads to one of the remaining types. The load flow Jacobian can be an effective index to approximately assess type I and II-2S instabilities, while types II-1 and II-2D require direct nonlinear analyses and eigenvalue analyses, respectively. The validity of the classification proposed has been verified through numerical simulations and theoretical analyses which take into account dynamic characteristics of generating units, loads, and tap-changing transformers     

消谐式逆变技术使输出电压高于输入电压的机理

通过对SPWM逆变技术、方波逆变技术和消谐式逆变技术的电压转换系数进行分析，证实了消谐式逆变器可以使输出的电压大于输入的供电电压。因此，将消谐式逆变技术应用于逆变器有利于电压利用率的提高。     

非线性负载下的多变流器谐波电压补偿控制策略

多变流器在接入非线性负载的情况下会引起电压畸变。为解决此问题,提出一种谐波电压补偿的综合控制策略。首先,采用虚拟同步发电机控制策略模拟同步发电机的外特性,使逆变器具有惯性和阻尼特性。其次,通过级联广义积分器构建谐波分离网络来提取相应的基波和谐波电流分量。紧接着结合虚拟阻抗构建基波处的感性虚拟阻抗去改善功率均分,以谐波处的阻容性可变虚拟阻抗去改变系统的输出阻抗来补偿相应的谐波电压。然后,在虚拟同步发电机的基础上采用多谐振电压控制器对输出电压的谐波进行抑制。最后,对所提的综合控制策略进行仿真研究,结果验证了所提策略在谐波电压补偿方面的正确性。     

基于谐波互阻抗的励磁涌流引发谐波电压畸变风险识别

弱联系电网中普通的空载变压器合闸操作就可能会因向电网注入了励磁涌流,而导致系统出现严重的谐波电压畸变,加大设备及负荷损毁的风险。提出了励磁涌流引发谐波电压畸变风险指标,该指标基于系统网络的谐波互阻抗,考虑了被操作主变的容量以及系统中发电机、负荷、线路、变压器等元件对谐波电压畸变的影响。利用该指标对某联网工程中励磁涌流引发的谐波电压畸变风险进行了评估,PSCAD仿真结果验证了所提指标的有效性。     

Development of high voltage harmonic measuring instruments for distribution systems using optical voltage sensor and current sensor

Application of an optical measuring technique was attempted in order to develop harmonic voltage and current measuring instruments for distribution systems. To develop the harmonic voltage measuring system using a Bi₁₂GeO₂₀ crystal as a sensing Pockels cell for high‐voltage distribution lines, zinc oxide elements were adopted as a voltage divider. Also, an optical current sensor system was improved on the harmonic current measuring system using an R₃Fe₅O₁₂ film as a Faraday device. In practical three‐phase distribution systems, the developed high voltage harmonic measuring devices using the optical voltage sensor and current sensor were compared with conventional harmonic analyzers for low voltage. As a result, it was confirmed that the developed high voltage harmonic measuring devices had satisfactory characteristics for practical use. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 84–93, 1999     

伪火花开关自放电电压特性与电压跌落过程实验研究

设计了典型参数下的伪火花放电开关,进行了空气介质下的电压特性实验,详细研究了气体压力,电极间隙距离,电极孔径和电极材料对伪火花开关耐受电压的影响;给出了伪火花开关放电电压与气压变化的关系曲线;测量了产生伪火花放电的气压范围和单间隙伪火花开关耐受电压的最大值,测得了伪火花放电与辉光放电的转折点气压,并对实验结果进行了理论分析。研究了伪火花开关电压跌落时间与放电电压的关系,首次将开关电压跌落过程分为暂态阶段和稳态阶段,讨论了放电电路参数,气体压力,开关结构和放电电压对电压跌落时间的影响。实验表明,在气压和开关结构不变的条件下,暂态过程时间由放电电压决定,电压越高,则所需时间就越短;稳态过程时间由放电电路参数决定,而与放电电压无关。最后讨论了真空洁净程度和开关加工与装配工艺对伪火花开关耐受电压的影响。     

Computer method of direct synthesis of nonlinear two-poles under time characteristics of current and voltage

The method of synthesis of nonlinear two-poles under the time characteristics of a current and voltage on its terminals. The algorithm is proved, and the parameters of the two-pole modeling influence of currents of converting electric locomotives of the next feeding zones on the external characteristics of traction substation of an alternating current are determined.     

A study of the loss characteristics of the amorphous magnetic material under nonsinusoidal wave magnetic flux

This paper presents a study on iron loss characteristics of an amorphous magnetic material under nonsinusoidal wave magnetic flux. The iron loss characteristics of the amorphous magnetic material have been compared to those of grain‐oriented magnetic steel sheets. Measurements of the iron loss have been carried out by means of an SST. It was found that the ratio of the iron loss increase of the amorphous magnetic material under the excitation by distorted waveforms and symmetric PWM waveforms is lower than that of grain‐oriented magnetic steel sheets. On the other hand, the ratio of the iron loss increase of the amorphous magnetic material under the excitation by asymmetric PWM waveforms is higher than that of grain‐oriented magnetic steel sheets. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(3): 11–18, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20004     

谐波对电容式电压互感器运行特性的影响研究

针对电容式电压互感器（Capacitor Voltage Transformers,CVT）在谐波干扰下二次侧产生畸变的问题,阐述了CVT的结构特性和工作原理,从系统传递函数角度分析了杂散电容和耦合电容对CVT高频特性的影响以及谐波干扰使CVT的测量误差发生的变化.为了进一步了解谐波对CVT运行特性的影响,运用仿真软件Matlab搭建包含杂散电容和耦合电容的CVT高频等效电路模型对其进行仿真试验,以获得CVT的幅频特性曲线.仿真结果表明,电网中的谐波电压会使CVT的测量误差产生变化,并不适宜直接用来测量谐波电压.     

Performance optimization of BiCMOS circuits under reduced supply voltage

As the supply voltage is reduced, the speed superiority of BiCMOS over CMOS may be diminished, but BiCMOS still has the advantage of inducing relatively smaller characteristic degradation in nMOS transistors by suppressing the drain voltage in the gate. Introducing a new quantitative methodology to evaluate hot electron-induced degradation of nMOS transistor characteristics, this report finds that both BiNMOS gates and CBiMOS gates will have a considerable superiority over CMOS gates in the voltage range from 2.5 V to 3.3 V, even with the same nMOS transistor characteristics. BiNMOS is 30% faster than CMOS owing to amplification of the pMOS drain current by an npn transistor. CBiCMOS is 40% faster and has a sevenfold longer life than CMOS. The speed improvement comes from amplification of both pMOS and nMOS drain currents by npn and pnp transistors, respectively, and the lifetime improvement is due to the effect of the voltage drop through the pnp transistors on the drain terminal of the nMOS transistors. The analytical methodology was also utilized to choose an optimum drain structure, although CMOS necessitates the LDD (lightly doped drain), SD (single drain) structure. Thus, the speed of the gates can be further improved, and the speed of CBiCMOS is expected to be 45% faster than that of CMOS gates. Even in the case of SD structure, the lifetime of CBiCMOS was estimated to be two orders of magnitude longer than that of CMOS with LDD structure. © 1998 Scripta Technica. Electr Eng Jpn, 121(4): 56–64, 1997     

电网电压不平衡及谐波状态下的并网逆变器控制策略

为了提高并网逆变器在电网电压不平衡及谐波状态下的适应能力,使其能够输出高质量的并网电流,需对传统并网逆变器控制策略进行改进。以αβ坐标系下LCL型并网逆变器模型为研究对象,提出一种基于准比例谐振(QPR)和电网电压前馈的控制策略。首先,分析了并网电流与其给定值和电网电压之间的关系,得出稳态误差及扰动分量产生的原因。然后,通过QPR控制策略来实现并网电流的无静差控制,引入电网电压前馈控制来抑制电网扰动对并网电流的直接影响。同时,为了提高传统锁相环在电网电压非理想情况下锁相精度及谐波抑制能力,对传统锁相环做进一步改进,以提高锁相环抗扰能力。最后,在Matlab/Simulink中进行仿真验证,仿真结果表明该控制策略能够在电网电压不平衡及谐波状态下得到高质量的并网电流,使逆变器能高效稳定运行,验证了该控制方法的有效性和正确性。