无刷直流电机驱动用IGBT逆变器能耗分析

为了预测电机系统的性能和提高设计的可靠性.根据无刷直流电机(BLDCM)的PWM调制原理和IGBT的损耗机理.采用损耗分离法提出了BLDCM驱动用IGBT逆变器的功耗计算模型.逆变器的通态损耗是与IGBT正向通态压降、电机电流和开关占空比有关的函数,而其开关损耗足开关器件的肝关时间、电机电流、逆变器的供电电压以及调制频率的函数.对提出的损耗模型进行了仿真计算和实验验证,仿真计算结果与实验结果具有较好的一致性.     

考虑脉冲宽度调制激励特征及松弛过程影响的铁磁材料损耗分离模型研究

准确高效求解非正弦条件下的磁损耗,对电工装备发热分析及优化设计具有重要意义。为了研究脉冲宽度调制(pulse width modulation,PWM)激励下铁磁材料的磁损耗建模方法,通过搭建磁通密度可控的PWM激励磁特性测试系统,测量获得不同工况下硅钢片的磁滞特性和损耗特性数据,并分析PWM激励的特征(电压波形、磁密波形、调制比)对损耗各分量的影响。同时,结合PWM激励时材料磁滞过程的分析,考虑电压突变为零时松弛过程对剩余损耗的影响,提出一种计及PWM激励特征及松弛过程的改进损耗分离模型,实现PWM激励下磁损耗的有效计算,并进行相关的实验验证。仿真及实验结果表明,所建立的模型具有较高的计算精度和工程适用性。     

PWM逆变器供电引起的轴向磁通非晶电机谐波损耗的解析计算

非晶合金材料具有出色的低损耗特性,适于用作高频电机的铁心,但PWM逆变器供电会导致高频电机谐波损耗严重增加。在电机初始设计阶段,快速准确计算出谐波损耗是轴向磁通非晶合金永磁电机设计及优化的关键。针对3D时步有限元计算耗时长的问题,改进现有多环等效模型的计算方法,推导了考虑PWM逆变器供电高次谐波电流影响的气隙磁通密度解析计算方法,并在此基础上推导了定子铁心损耗及考虑涡流反作用影响的转子涡流损耗的解析计算方法。将谐波损耗的解析计算值与样机实验值以及3D有限元计算值进行对比,结果显示谐波损耗的平均计算误差仅为9.69%,解析模型具有较高的计算精度。     

多因素影响下永磁电机定子铁耗计算

经典的常系数及分段常系数铁耗模型不能准确计算具有宽调速范围的变频永磁同步电机铁心损耗,也无法考虑到温度对铁耗损耗的影响。基于传统两项模型,综合考虑旋转磁场、高次谐波、趋肤效应、磁路饱和、小磁滞环路以及温度的影响,提出多因素影响下的永磁电机铁心损耗模型。针对一台PWM逆变器供电的内置式永磁同步电机定子铁心损耗进行计算,将计算值与实验值进行比较分析,结果表明,与传统模型相比,该模型在宽频调速范围内具有更高的准确性。     

逆变器供电永磁同步电机铁耗和永磁体损耗分析

为了模拟逆变器供电变频调速永磁同步电机铁耗和永磁体损耗的精确计算,采用非线性电感参数电机模型与矢量控制技术构建电机系统性能仿真平台,开展基于SVPWM矢量控制的高密度永磁同步电机损耗相关技术研究。以48槽8极高密度永磁同步电机为例,研究逆变器供电变频调速永磁同步电机电流时间谐波对铁耗和永磁体损耗的影响,仿真分析逆变器参数与定子电流畸变率之间的关系。仿真分析表明,电流时间谐波是产生永磁体涡流损耗的主要因素;电流时间谐波对铁心涡流损耗影响大,对铁心磁滞损耗影响小;在一定的范围内,当载波比和调制比增大时,电流畸变率减小,铁耗和永磁体涡流损耗也随之减小。与正弦波供电方式相比,用逆变器供电仿真计算得到的铁耗和永磁体损耗值更接近样机实验数据,进一步验证了仿真分析方法的准确性。     

变频器驱动下异步电机铁心损耗的研究

本文介绍了一种计算变频器驱动下异步电机铁心损耗的方法。该方法在分立铁耗模型的基础上,结合贝塞尔函数,推导出了变频器供电下异步电机铁耗的计算模型。在考虑变频器参数对铁心损耗的影响的情况下,建立了变频器供电时和标准正弦供电时铁心损耗的数量关系。分析了变频器供电时电机铁心损耗与变频器调制比和载波比的变化关系。并针对一台4500kW变频电机铁心损耗进行了计算分析。     

PWM逆变器供电下非晶永磁电机的损耗分析

为了研究PWM逆变器供电情况下,非晶永磁电机损耗的分布规律,本文分析了考虑加工影响的非晶电机定子铁心损耗的计算方法以及考虑磁导谐波、磁动势谐波和载波谐波的永磁体涡流损耗分离方法。利用有限元方法分析了一台表贴式非晶永磁电机在PWM逆变器供电情况下的损耗分布规律。结果显示,由载波谐波引起的损耗是该电机最主要的损耗分量,约占总损耗的66.0%。     

PWM逆变器供电异步电机端部过电压的分析和仿真

PWM逆变器供电时电机的端电压出现幅值增高和振荡现象，对电机的匝间绝缘造成很大的威胁，本文提出了一种可以判断PWM逆变器供电异步电机端部过电压波形的实用仿真方法，该方法根据PWM逆变器供电电机系统的特征建立系统的仿真模型，将电机用实测的等效的阻抗频率特性来替代，将三相电缆等效成一个二端口网络，通过傅立叶分析计算电机端部的暂态过电压。与实测波形的对比，证明这种方法的仿真结果可以与实际情况良好地吻合。     

电流谐波对不同绕组形式永磁同步电机损耗研究

由PWM逆变器供电的永磁同步电动机定子电流中含有大量时间谐波,这些谐波作用于电机铁心和永磁体上产生损耗,不同绕组形式永磁同步电机受电流时间谐波的影响也不相同。建立集中绕组永磁同步电机和分布绕组永磁同步电机的有限元模型,将实测得到的PWM逆变器供电下电机的定子电流进行分解,得到各次电流谐波,并将电流谐波分别代入集中绕组电机和分布绕组电机进行仿真,研究谐波损耗对电机效率的影响,通过实验对比两种电机在电流谐波影响下的效率。     

非正弦激励下纳米晶材料高频磁心损耗的计算方法改进与验证

软磁材料广泛应用于各种电气设备的铁心，磁心损耗的精确计算关系着电气设备的效率。尤其是高频非正弦激励条件下磁心损耗的精确计算，是逆变器、电力电子变压器和高频电抗器等电力电子装置的优化设计的重要组成部分。该文首先总结了几种非正弦激励下的磁心损耗的计算方法，对比几种改进的Steinmetz经验公式，分析磁化过程对磁心损耗的影响；然后提出一种考虑磁感应强度变化率的改进Steinmetz波形系数公式（WcSE）计算模型，推导出高频方波和矩形波激励下的损耗计算表达式；接着搭建高频非正弦激励下的软磁材料磁特性测试系统，在频率为10～70kHz范围内对环形纳米晶样品（FT-3KL和FT-3KS）进行不同占空比的方波和矩形波激励下的高频磁特性实验，得到方波和矩形波激励下的磁心损耗实验测量值；最后对比实验值和几种修正Steinmetz模型的计算值，并进行误差分析，得到改进的WcSE计算模型的平均计算误差在20%以内，均小于Steinmetz修正公式、修正广义Steinmetz公式和WcSE的计算误差的结论，验证了所提改进的WcSE新模型的计算精确性，为电力电子装置的磁心损耗预测以及优化设计提供了重要依据。     

PWM逆变器供电异步电机端部过电压的分析和仿真

PWM逆变器供电时电机的端电压出现幅值增高和振荡现象,对电机的匝间绝缘造成很大的威胁,本文提出了一种可以判断PWM逆变器供电异步电机端部过电压波形的实用仿真方法,该方法根据PWM逆变器供电电机系统的特征建立系统的仿真模型,将电机用实测的等效的阻抗频率特性来替代,将三相电缆等效成一个二端口网络,通过傅立叶分析计算电机端部的暂态过电压。与实测波形的对比,证明这种方法的仿真结果可以与实际情况良好地吻合。     

Iron Loss Calculation of AC Filter Inductor for Three‐Phase PWM Inverters

In recent years, remarkable advancement of new power semiconductor devices, such as SiC and GaN, enables the increase of switching frequency of power converters, and hence the volume of passive components, such as ac filters and transformers, can be reduced. However, temperature rise caused by the inductor loss is increasing, and hence iron loss evaluation of the inductor is one of the most important issues to realize high power density converters. Conventionally, an improved generalized Steinmetz equation (iGSE) has proposed in order to calculate the iron loss under a pulse voltage magnetizing condition. However, accurate iron loss calculation of the ac filter inductor used in a PWM inverter cannot be realized. The authors have proposed two methods of iron loss evaluation of ac filter inductors. The first one is a loss map method which can calculate the iron loss without using a real PWM inverter. Another one is an ILA (Inductor Loss Analyzer) which can measure the iron loss in every switching period in a real PWM inverter. In this paper, comparisons of the iron loss between the ILA and the loss map method on both the single‐phase and three‐phase inverters are studied. It is found that iron loss of the ac filter inductor in the three‐phase PWM inverter which is calculated by the loss map method cause a large error on a specific condition. In order to prevent the calculation error, the authors proposed a revised loss map method and proved the effectiveness of the method.     

一种降低无刷直流电机EPS系统损耗的PWM控制策略

无刷直流电机电动助力转向(Electric Power Steering, EPS)系统由车载蓄电池供电,采用由MOSFET构成的三相电压型逆变器驱动.为了降低无刷直流电机EPS系统的损耗,本文提出了一种新颖的脉冲宽度调制(Pulse Width Modulation, PWM)控制策略,即无论EPS系统处于助力状态、回正状态还是阻尼状态,当检测到某一个MOSFET反并联的续流二极管导通时,就给该MOSFET的门极施加驱动信号,以此来降低续流二极管的导通压降和导通损耗,减少其发热,提高逆变器的工作效率.实验证明,本文提出的PWM控制策略在降低EPS系统损耗的同时可以对汽车转向过程的各个环节进行有效的控制,且该方法实现简单,具有较强的实用性.     

Active cancellation of the common-mode voltage produced by a voltage-source PWM inverter

This paper proposes an “active common-mode noise canceler” that is capable of eliminating the common-mode voltage produced by a voltage source PWM (pulsewidth modulated) inverter. It generates a compensating voltage which has the same amplitude as, but the opposite phase to, the common-mode voltage produced by the PWM inverter. The compensating voltage is superimposed on the inverter output by a common-mode transformer. As a result, the common-mode voltage applied to the load is canceled completely. The design method of the active common-mode noise canceler is also presented in detail. A prototype has been constructed and tested to verify the effectiveness for an induction motor drive system of 3.7 kW using an IGBT (insulated gate bipolar transistor) inverter. Some experimental results show that the proposed active common-mode noise canceler makes a significant contribution to eliminating the common-mode current or the ground current, and it prevents an electric shock from being received by anyone handling it.     

An experimental study of the operating characteristics of an asynchronous motor with pulse supply

The fundamentals of design procedure of performance data of controlled asynchronous motors (AMs) supplied with pulse voltage are stated in this article. The proposed model is based on a L-shaped equivalent circuit for each of harmonics, on which the curve of applied to a phase voltage is displayed. It is proposed to find the increase of magnetic iron loss caused by hysteresis in proportion to the peak value of the pulse voltage. The influence of PWM voltage on magnetic hysteresis loss is determined by using a coefficient depending on the effective values of fundamental and higher harmonics of the EMF and voltages, as well as the coefficient taking into account the increase of electrical resistance of iron due to the skin effect. In a similar way, it is proposed to take into account magnetic losses in the rotor that are occasioned only by the influence of higher harmonics. It is proposed to determine the increase of resistance and decrease of the inductance of short-circuited rotor of the influence of currents of higher harmonics by the well-known Interelectro methodology. The resulting values of consumption current, power factor, effective power, and consumption power of an asynchronous motor with pulse voltage are calculated taking into account the total effect of currents and voltages of fundamental and higher harmonics. Based on the methodology that we have laid out, a program was written and modeling was carried out of the operational characteristics of an asynchronous motor with a power of 180 W supplied by a PWM inverter with a fundamental frequency of 50 Hz. In addition, the harmonic composition of pulse voltage was obtained by processing the oscillograms taken from phase windings of the motor supplied by the frequency converter. To experimentally check of the proposed model, an experimental plant for loading the asynchronous motor was assembled and the operational characteristics of asynchronous motor with the fundamental harmonic of 50 Hz were determined. The experimental results showed satisfactory convergence with the calculated results that makes it possible to recommend the proposed methodology to evaluate the energy indices of frequencycontrolled asynchronous motors.     

A modified cascade transformer-based multilevel inverter and its efficient switching function

A modified multilevel PWM inverter is proposed to increase the number of output voltage levels and to improve the system characteristic of a prior 11-level shaped PWM inverter scheme. In appearance, it consists of three full-bridge modules and a cascade transformer; therefore, the configuration of the proposed multilevel PWM inverter is equal to that of the prior one. Only the turn-ratio of one transformer and its corresponding switching function are different from each other. Based on the difference, the proposed multilevel PWM inverter has two promising advantages. First, output voltage levels increase almost two-fold. Consequently, it can generate more sinusoidal output voltage waves. Second, due to a suitable switching pattern, it lightens power imposed on the transformer, which is used for compensating output voltages with chopped pulses between step levels. Operational principle of the proposed 19-level shaped PWM inverter is analysed with comparisons of the prior 11-level shaped PWM inverter. The validity of the proposed inverter system is verified by computer-aided simulations and experimental results based on a 1 kW prototype.     

Position Sensorless Control of Interior Permanent Magnet Synchronous Motors Using Unknown Input Observer for High-Speed Drives

This paper proposes a new position sensorless control for interior permanent-magnet synchronous motor (IPMSM) drives fed by overmodulation mode pulsewidth modulation (PWM) voltage source inverter. It is attractive to expand the speed range of the IPMSM for application to electric vehicles, electrical household appliances, and so on. An overmodulation mode PWM voltage-source inverter makes it possible to solve problems such as efficiency, wide speed range operation, and so on. Most position sensorless controls based on inverter output voltage knowledge, however, cannot directly be utilized because the voltage reference obtained by the controller is not equal to the inverter output voltage. This paper proposes unknown input observer to estimate rotor position without voltage knowledge, and investigates robustness to inductance variation.      

基于PWM整流器双PFC模型的电机能量回馈系统

用PWM整流器取代通用变频器的二极管整流电路,采用双PWM整流器/逆变器,设计了电机能量回馈系统。通过分析PWM整流器的数学模型,提出了一种基于α-β静止参考坐标系的PWM整流器双功率因数校正变换器(PFC)定频控制策略。在两相静止坐标系中将PWM整流器等效为2个与传统单相PFC类似的电路结构,然后根据电压空间矢量调制理论,分析了开关信号由两相静止坐标系到三相静止坐标系变换的控制策略。实验结果表明,该系统不仅能够将电机机械能转化的电能有效地回馈到电网,而且能够有效抑制注入电网的谐波,实现网侧单位功率因数控制。     

Low-Speed Drive of PWM-VSI-Fed Brushless Self-Excited Synchronous Motor

The brushless self-excited synchronous motor with halfwave rectified field circuits has been invented already by Nonaka. For the low-speed drive of the motor a new method of the voltage supply which superimposes a higher-order harmonic component on sinusoidal low-frequency voltage by a pulsewidth modulated (PWM) GTO inverter is presented. The amplitude and frequency of the fundamental component and those of the harmonic component are controlled independently by a microcomputer-based PWM strategy. It is confirmed from the experimental results that controllable brushless self-excitation and smooth low-speed operation without torque pulsation are achieved by the proposed scheme.     

PWM整流器虚拟电网磁链定向矢量控制仿真研究

三相电压型PWM整流器与三相交流变频调速电机定子电路有很大的相似性.采用类似于交流电机磁链观测的方法来构造一个虚拟电网磁链,可以代替电网电压作为PWM整流器矢量控制中的定向矢量,达到省去交流侧电网电压传感器,降低PWM整流器成本的目的.根据交流电机磁链观测器的设计方法,设计了虚拟电网磁链观测器,并构造了基于Matlab/Simulink的PWM整流器虚拟电网磁链定向无电网电压传感器的仿真模型.仿真结果验证了观测器的可靠性和控制方案良好的动静态特性.