Indirect Vector Control of Linear Induction Motors Using Space Vector Pulse Width Modulation

Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.

基于虚拟电压矢量的双三相直线磁通切换永磁电机容错SVPWM策略

高可靠性是电梯驱动系统的首要指标。针对双三相直线磁通切换永磁(dual-three-phase linear flux switching permanent magnet,DTP-LFSPM)电机单相开路故障,提出一种基于虚拟电压矢量的容错空间矢量脉宽调制策略。首先,基于单相开路故障下的五维变换矩阵计算得到故障后的32个空间电压矢量分布。然后,筛选部分空间电压矢量,以z子空间电压幅值为零且每个扇区产生对称的脉宽调制波形为目标,重构得到12个虚拟电压矢量,相邻的2个虚拟电压矢量都由3个基本电压矢量组成,并用于合成参考电压矢量,不仅可以减少单相开路故障容错控制时的电流谐波,而且具有计算简单,易于硬件实现等优点。最后,搭建DTP-LFSPM电机驱动控制系统仿真与实验平台,仿真和实验测试结果证明所提容错策略的正确性和有效性。

一种PMSM位置伺服系统的动态建模与控制

本文根据永磁同步电机(PMSM)的基本电磁关系及其动态数学模型建立了位置伺服控制模型,按照闭环负反馈控制原理,设计了具有电流、速度、位置三闭环的位置控制系统。首先,根据PMSM矢量控制的特性,利用3S/2S和2S/2R的坐标变换理论,建立了位置伺服系统在同步坐标系下的动态数学模型,同时给出了按照转子磁场定向的位置控制策略和算法;其次,研究了基于空间矢量脉宽调制(SVPWM)的数字实现,并根据电机的数学模型,在MATLAB/Simulink环境中构建了三环模型,同时搭建了基于DSP实验样机。在仿真和实验中直轴、交轴以及速度和位置均采用PI控制,在控制参数的整定过程中,遵循先内环(电流环),后速度环,再位置环的增量调试原理,实现了同步电机的位置闭环控制;最后,对仿真结果和试验结果进行了对比分析,说明了模型的正确性和有效性。

无刷直流电机转矩脉动抑制策略的仿真研究

无刷直流电机(Brushless Direct Current Motor,BLDCM)作为一种广泛使用的电机装置,在换相过程中会造成母线电流波动,产生较强的转矩脉动,影响电机运行稳定性。本文对无刷直流电机产生换相转矩脉动和续流转矩脉动的原因进行分析,针对采用传统PWM调制出现的换相转矩脉动和续流转矩脉动过大的问题,采用了一种基于传统PWM调制优化后的改进型PWM调制策略,该调制策略能够有效的抑制换相转矩脉动和续流转矩脉动。MATLAB/Simulink仿真结果表明改进型PWM调制策略和传统的PWM调制相比在转矩脉动抑制上有更加优良的表现。

基于51单片机定时器的直流电机PWM调速设计

脉宽调制(PWM)在直流电机调速中应用十分广泛。为了实现基于51单片机定时器功能的高精度脉宽调制直流调速,设计了硬件电路原理和程序流程,分析了单片机中断系统参数对PWM周期精度的影响,确定了定时器参数,用汇编语言实现脉宽调制占空比的计算。在每个PWM周期内,定时器参数要使定时器中断按照正确顺序产生,就可使系统正常运行,运用仿真软件验证了此设计方法的有效性和可行性。

基于DSP的不连续脉宽调制统一化实现方法研究

在高速永磁同步电机驱动场合,逆变器的开关损耗是影响电机系统驱动效率的主要因素之一,相比传统的七段式SVPWM调制,不连续脉宽调制(DPWM)能极大地降低开关损耗,提高系统效率。现有研究的DPWM调制策略有6种,不同调制策略的降低开关损耗性能及输出谐波都各有差异,为实现系统综合性能最优,采用分段复合调制或目标优化调制。基于DSP应用平台,提出一种新的不连续脉宽调制的统一化实现方法,分析不同调制方法下零序电压中零矢量的分配系数与三相指令电压的关系,针对第二、第三类不连续脉宽调制下零矢量分配系数不是定值的问题,引入基准指令电压,并根据基准指令电压中最大值与最小值之和的正负确定分配系数的值,完成了SVPWM及6种DPWM的统一化实现,不同的调制方法之间可快速切换,实现方法便捷可靠,仿真及实验结果验证了该方法的有效性。

Regenerative Braking Strategy for Motor Hoist by Ultracapacitor

Rising concern in environmental issues on global scale has made energy saving in powered equipment a very important subject.In order to improve the energy efficiency and driving range of a motor hoist,a regenerative braking system is designed and discussed.The system takes a unique ultracapacitor-only approach to energy storage system.The bi-directional bride DC？DC converter which regulates current flow to and from the ultracapacitor operates in two modes：boost and buck,depending on the direction of the flow.In order to provide constant input and output current at the ultracapacitor,this system uses a double proportional-integral（PI） control strategy in regulating the duty cycle of PWM to the DC？DC converter.The permanent magnet synchronous motor（PWSM） drive system is also studied.The space vector pulse width modulation（SVPWM） technique,along with a two-closed-loop vector control model,is adopted after detailed analysis of PMSM characteristics.The overall model and control strategy for this regenerative braking system is ultimately built and simulated under the MATLAB and Simulink environment.A test platform is built to obtain experimental results.Analysis of the results reveals that more than half of the gravitational potential energy can be recovered by this system.Simulation and experimentation results testify the validity of the double PI control strategy for interface circuit of ultracapacitor and SVPWM strategy for PMSM.

High Performance Control of Matrix Converter Fed Induction Motor Drive System

Matrix converter fed motor drive is superior to pulse width modulation inverter drives since it not only provides bi-directional power flow,sinusoidal input/output currents,unity input power factor,but also allows a compact design due to the lack of DC-link capacitors for energy storage.In this paper,model and control of matrix converter fed induction motor drive system are analyzed.A combined control strategy is simplified and improved,which realizes space vector pulse width modulation of matrix converter and rotor flux oriented vector control technique for induction motor drive simultaneously.This control strategy combines the advantages of matrix converter with the good drive performance of vector control technique.Experimental results demonstrate the feasibility and effectiveness of the proposed control strategy.

Optimization of total harmonic current distortion and torque pulsation reduction in high-power induction motors using genetic algorithms

This paper presents a powerful application of genetic algorithm (GA) for the minimization of the total harmonic current distortion (THCD) in high-power induction motors fed by voltage source inverters, based on an approximate harmonic model. That is, having defined a desired fundamental output voltage, optimal pulse patterns (switching angles) are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for the two cases of three and five switching instants in the first quarter period of pulse width modulation (PWM) waveform are presented. Presence of harmonics in the stator excitation leads to a pulsing-torque component. Considering the fact that if the pulsing-torques are at low frequencies, they can cause troublesome speed fluctuations, shaft fatigue, and unsatisfactory performance in the feedback control system, the 5th, 7th, 11th, and 13th current harmonics (in the case of five switching angles) are constrained at some pre-specified values, to mitigate the detrimental effects of low-frequency harmonics. At the same time, the THCD is optimized while the required fundamental output voltage is maintained.

Characteristics of permanent magnet linear synchronous motor fed by spwm inverter based on field-circuit coupled method

Presented field-circuit coupled adaptive time-stepping finite element method to study on permanent magnet linear synchronous motor (PMLSM) characteristics fed by SPWM voltage source inverter.In air-gap field where the direction or magnitude of the field is changing rapidly,the smallest elements are demanded due to high accuracy to use adaptive meshing technique.The co-simulation was used with the status space functions and time-step finite element functions,in which time-step of the status space functions was the smallest than finite element functions'.The magnitude relation of the normal elec- tromagnetic force and tangential electromagnetic force and the period were attained,and current curve was very abrupt at current zero area due to the bigger resistance and leak- age reactance,including main characteristics of motor voltage and velocity.The simulation results compare triumphantly with the experiments results.

Development of a Microcontroller Based DC Motor Speed Control System

This work reports the development of a microcontroller based control system to change the speed?of?a DC motor. Pulse Width Modulation?(PWM)?technique was used to control the amount of power delivered to the load (the DC motor) without dissipating any wasted power. The components and assembly of this microcontroller circuit are highlighted in this paper, and the constructed circuit tested. This device was used to control the speed of a rotating fan attached to a DC motor. The DC motor speed variations were read from a Tachometer connected to this motor and the results obtained show good agreement with our expectations. DC Motor speed microcontroller devices find applications in many areas of life, and its applications in small scale industrial settings will no doubt enhance the quest for development in a developing nation like ours.

电动汽车驱动电机高频边带噪声客观评价研究

针对声压级不能完全反映人耳对声音感受的问题,文章选择多种工况对电动汽车驱动电机高频边带噪声进行客观心理学参量评价。首先,进行驱动电机噪声数据采集实验并建立样本库。其次,计算样本的客观心理学参量并运用主成分分析法进行贡献量分析,并将客观心理学参量的六个维度降低至两个维度。最后,研究多种工况下两种客观心理学参量的变化规律,尤其对随机载波频率脉宽调制(Random Carrier Frequency Pulse Width Modulation,RCFPWM)策略下电机高频边带噪声进行客观评价对比分析。结果表明,主成分分析法(Principal Component Analysis,PCA)实现了多维客观心理学参量的降维,高频边带噪声中客观心理参量的主要贡献量为尖锐度和响度;不同工况条件对尖锐度和响度存在不同程度的影响,尤其是受转速变化影响较为明显;RCFPWM在降低高频边带噪声声压级的同时实现了对尖锐度幅值的抑制。文章所研究的内容不仅能够简化电机高频边带噪声客观评价流程,而且可以为电驱动总成声品质优化设计提供实验依据。

同步磁阻电动机新型位置估计与电感参数辨识

针对同步磁阻电动机电流导数和基本脉宽调制励磁(FPE)的方法数据处理量大的问题,研究了当前广泛使用的主流无传感器估计技术,从而提出了一种改进的估计方法并将其应用在同步磁阻电机的控制系统中。所提方法在每个脉宽调制(PWM)周期内仅需对两个有功电压矢量和一个零电压矢量作用下的单相电流进行采样、求导并计算,相比于传统方法中需要对两个有功电压矢量和两个零电压矢量作用下的三相电流进行采样、求导并计算而言,该创新估计算法不仅可以节约硬件成本,同时也大大降低了数据处理量。并且创新的估计算法在不降低精度和增加算法复杂程度的基础上,同时对电感参数实现精准辨识,使得该估计算法辨识的参数变多。使用仿真平台对同步磁阻电动机无传感器控制系统进行了仿真搭建。最后搭建了系统相应的硬件实验平台,通过实验验证了所提估计算法的优越性。

五相永磁同步电机改进型无差拍直接转矩和磁链控制

传统无差拍直接转矩磁链控制(DB-DTFC)策略应用于五相永磁同步电机(PMSM)时存在稳态性能差、转矩和磁链耦合、谐波电流大等问题,该文提出一种改进型DB-DTFC策略。首先,为实现转矩和磁链的解耦控制,在两相静止坐标系中对定子电压与转矩和磁链之间的关系进行分析,求解满足控制要求的电压矢量。其次,设计电流和磁链观测器补偿数字控制系统的延时。再次,采用基于4个非零电压矢量的空间矢量脉宽调制(SVPWM)技术,抑制相电流的3次谐波分量。实验结果表明,该策略计算简便,抑制了转矩和磁链脉动,降低了3次谐波电流,提升了控制系统动稳态性能。

基于PWM占空比优化的PMSM预测直接转矩控制

针对永磁同步电机PMSM(permanent magnet synchronous motors)传统直接转矩控制DTC(direct torque control)存在开关频率不规则、开关噪声的频率范围太宽和死区补偿算法复杂等问题,提出了一种基于优化脉宽调制PWM(pulse width modulation)和死区补偿的PMSM预测DTC方法。该方法首先在已知零电压矢量的基础上,根据预测转矩和磁通误差来选择2个其他有效电压矢量,与此同时,也考虑反电动势和磁通-转矩耦合器;接着,利用1个零电压矢量和2个其他有效电压矢量预测每个采样周期的转矩和磁通变化量,其中,3个电压矢量的开关周期由转矩和磁通误差以及上一步计算出的预测转矩和磁通变化量共同决定;然后,采用死区补偿算法和改进的PWM来减小死区效应,以提高预测效果;最后,通过仿真和实验验证了所提方法的有效性和优越性。研究结果表明,所提方法在转矩控制和磁通控制效果要明显优于其他方法,且极大地降低了开关损耗。

五相PMSM相邻两相开路故障容错控制策略

相永磁同步电机(permanent magnet synchronous motor, PMSM)发生相邻两相开路故障会导致驱动系统不稳定运行,针对这种故障状况,提出一种基于空间矢量脉宽调制(space vector pulse width modulation, SVPWM)技术的容错控制策略。首先构建永磁同步电机数学模型;进而为使机电能量实现平稳转换,重新构建降阶变换矩阵,得到故障后剩余相容错电流表达式;然后利用SVPWM技术,计算故障下空间电压矢量,建立6个扇区,进行目标矢量合成,进而计算相应基本合成电压矢量的作用时间,并给出对应扇区的空间电压矢量选择顺序;最后进行Matlab/Simulink仿真验证,仿真结果与理论计算一致,有效验证了所提SVPWM容错控制策略的正确性。利用该容错控制策略,五相永磁同步电机在故障状态下的运行性能得到明显改善,电机实现稳定运行。所提控制策略与传统电流滞环跟踪脉宽调制(pulse width modulation, PWM)控制方式对比分析,证明所提策略存在优越性。

一种改进的CHB多电平变换器PWM调制策略

级联H桥CHB(cascaded H-bridge)多电平变换器是中压大功率电机驱动系统最广泛采用的拓扑,传统LS-PWM和PS-PWM不能很好地兼顾输入、输出电流的谐波性能,对比了CHB多电平变换器在这两种调制策略下的输入和输出THD,分析了两种方法下输入、输出波形产生区别的本质原因,进而探讨了一种局部载波移相PWM调制方法。该方法吸收了两种调制方法的优点,发挥PS-PWM调制时模块功率均衡和网侧输入电流谐波低的特点以及LS-PWM输出电能质量好的特点。最后,搭建了三相七电平CHB变换器实验平台,对局部载波移相PWM调制策略进行了验证。

一种低电压尖峰的高增益Y源-LLC变换器

为推动新能源接入直流配电网,减少变换环节和损耗,隔离型高增益DC/DC变换器是关键接口设备。因此,提出一种低电压尖峰的高增益Y源-LLC变换器,结合Y源阻抗网络和LLC谐振腔的增益特性,实现更高的升压能力,降低电压尖峰。进一步提出脉冲宽度调制和脉冲频率调制相结合的运行方式,在缩小开关频率调整范围的同时,实现全功率下宽输入输出电压工作范围,提高变换器在新能源直流并网中的适用性。最后,对所提变换器性能进行分析,搭建实验样机验证其可行性和理论分析的正确性。

扩展卡尔曼滤波参数辨识下永磁同步电机模型预测转矩控制

为了提高模型预测转矩控制的稳态性能,提出一种空间矢量脉宽调制(SVPWM)策略下的无差拍模型预测转矩控制。针对定子电阻与电感对无差拍算法控制效果的重要影响,使用扩展卡尔曼滤波器对模型中的定子电阻、电感参数同时进行在线辨识,以提升算法的参数鲁棒性。首先,对电磁转矩和定子磁链幅值使用无差拍控制,解出两相旋转坐标系下的参考电压矢量,并送入SVPWM进行调制,从而有效抑制了转矩脉动;然后,推导出定子电阻与电感出现不可抗力误差时,dq轴输出电压存在严重偏离理想值的问题;最后,使用扩展卡尔曼滤波器对模型中的电感和电阻参数同时进行在线辨识,并将辨识结果实时反馈至模型中。通过仿真和实验将所提算法的稳态性能、动态性能及参数鲁棒性进行了对比分析,从而证实了所提算法的优越性。

基于虚拟电压矢量的磁场定向控制策略研究

针对双三相永磁同步电机(PMSM)矢量控制系统中定子相电流的谐波问题,在采用传统两矢量空间矢量脉宽调制算法的基础上,提出基于最大四矢量的空间矢量脉宽调制算法的磁场定向控制策略。其次,针对最大四矢量的空间矢量脉宽调制算法计算量大,设计复杂的问题,又提出了基于虚拟电压矢量的空间矢量脉宽调制算法的改进型磁场定向控制策略。最后,通过MATLAB/Simulink仿真平台,验证所提出的改进型控制算法策略的有效性。