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。

基于单片机的直流电机变频调速方法与仿真

针对电机谐波损耗及逆变器输出谐波信号影响直流电机变频调速的稳定性,导致调速性能不佳等,提出一种基于单片机的直流电机变频调速方法。建立直流电机变频调速状态空间模型,通过上述模型获取变频调速系统的运行状态;采用电流、速度双闭环PI控制器实现直流电机的变频调速初步控制,使直流电机变频调速系统可同时满足静态性能与动态性能;将直流侧电压输入至SVPWM脉宽调制系统,进一步降低电机谐波损耗和脉动转矩,实现变频调速的精确控制。仿真结果表明,所提方法的直流电机变频调速稳定性更佳、精度更高,整体效果更佳。

模块化多电平逆变电路的调制算法研究

针对永磁同步电机传统三电平逆变电路无法满足高压场景的问题,采用空间矢量脉宽调制算法对模块化多电平逆变电路进行调制分析,观察其输出电压波形。然后针对模块化多电平逆变电路各相之间容易出现环流现象,对电容电压平衡控制算法进行简化。在Matlab/Simulink中搭建模型仿真,观察和分析模块化多电平逆变电路的输出电压,实验结果验证了采用空间矢量脉宽调制算法对改善模块化多电平逆变电路的输出特性的有效性和简化后的电容电压平衡控制算法具有稳定性。

L型双输出三电平变换器驱动开绕组电机研究

为简化驱动开绕组异步电机(OEWIM)的双逆变器结构,提出一种L型双输出三电平变换器(L-DO-TLC)拓扑。将T型三电平拓扑与九开关拓扑相结合,通过器件复用方式简化拓扑结构,仅需15个开关器件即可实现双三电平输出,有效降低了系统成本。首先详细分析了L-DO-TLC拓扑工作机理,采用含直流偏置的正弦脉宽调制(SPWM)策略实现了双端口独立输出。在此基础上,根据OEWIM驱动的特殊需求及所提拓扑特点,给出一种双端口互差120°OEWIM驱动接线方案并建立了系统数学模型,给出了电压空间矢量分布图。然后利用矢量解耦思想,对双输出端口调制度进行了研究,确立双端口互差120°OEWIM驱动的稳定运行区间。最后,对所提拓扑及控制策略的可行性和有效性进行了验证。

高温气冷堆吸收球停堆驱动机构机柜的抗干扰设计研究

步进电机驱动器是高温气冷堆核电站吸收球停堆驱动机构机柜的主要设备,采用脉冲宽度调制(Pulse Width Modulation,PWM)技术,脉冲宽度调制过程产生的高次谐波分量又反向影响驱动器的工作稳定性和精度,严重时可能引发吸收球误落或拒落而影响反应堆运行安全。本研究旨在制定合理的抗干扰方案,降低PWM脉宽调制机理带来的危害及其影响。在充分掌握PWM产生干扰的传输路径、作用机理和影响程度的基础上,定制适用于高温堆吸收球停堆驱动装置工作环境的光电隔离器、电抗器和滤波器布置在干扰传输路径上阻断干扰传播,降低干扰影响。经过优化设计研究,可使得步进电机每运行20圈,角度偏差在1°之内,满足了控制精度要求,防止了吸收球误落或拒落风险,提升了吸收球停堆驱动机构的运行可靠性。

表贴式永磁电机在PWM激励下永磁体涡流损耗计算模型

针对现有模型难以计算PWM激励下表贴式永磁电机永磁体涡流损耗问题,提出了一种计算由PWM谐波引起的永磁体内涡流损耗计算模型。该模型通过磁导率分布函数获取气隙径向磁密,能够考虑定子开槽及谐波电流影响。首先,在忽略涡流反作用情况下解析计算了永磁体内磁密变化率;然后,应用有限差分法数值计算了永磁体内电位,综合得到了涡流损耗;最后,用有限元法验证了模型的准确性。研究结果表明:随着永磁体分段数的增大,涡流损耗减小,涡流反作用也随之减弱;永磁体涡流损耗主要由1倍、2倍开关频率附近电流谐波引起。

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。

双三相永磁同步电机双平面SVPWM算法研究

提出一种双三相永磁同步电机(DT-PMSM)的双平面空间矢量脉宽调制(SVPWM)算法,基于矢量空间解耦(VSD)模型,通过矢量合成的方法,分别在α-β和z_(1)-z_(2)平面构建虚拟矢量,构建的虚拟矢量在另外一个子平面的电压矢量幅值为零,从而实现对α-β和z_(1)-z_(2)子平面参考电压矢量的独立控制,即可实现DT-PMSM双平面四维电流矢量控制,对六相逆变器死区效应等非线性因素进行补偿,与常用单平面四矢量SVPWM实现的二维电流矢量控制方法相比,明显降低了谐波电流。实验结果验证了所提算法的有效性和可行性。

一种抑制高速电机低次电流谐波的调制方法

针对高速永磁同步电机低载波比、数字控制延时所引起的电流谐波较大的问题,提出一种抑制低次电流谐波的改进型特定次谐波消除调制方法。首先,对该调制方法的调制波形原理和数字实现特点进行分析,建立新的电压谐波方程和开关角求解方程;其次,以电流总谐波失真为目标优化函数,研究了调制比和载波比对开关角分布、电流谐波含量的影响;最后,以三相高速永磁同步电机为研究对象,搭建系统仿真模型对所提调制方法进行验证。验证结果表明,通过与特定次谐波消除调制方式相比,所提调制方法计算量更少,可以提高输出脉宽调制波形的对称性,具有更优的低次电流谐波抑制能力。

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SVPWM的永磁同步电机矢量控制方法研究

随着伺服电机在工业自动化领域中的应用,针对伺服电机矢量控制系统运行稳定问题,研究两电平空间矢量脉宽调制(SVPWM)算法,建立基于转速环和电流环PI调节器的双闭环永磁同步电机矢量控制模型,在系统转速环设计一阶自抗扰控制器(ADRC),对该电机矢量控制方式进行优化。通过三相PWM波形在空载和负载情况下的脉冲宽度,电机转速以及转矩变化来对该永磁同步控制系统进行验证。仿真结果表明:优化后的永磁同步电机矢量控制方案能够有效提高响应速度和控制精度。

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。

大转矩鼠笼异步调宽电动机设计

在过去的变频异步电动机设计基础上,从电磁设计要点到结构设计进行了详细论述,验证了改进后的电动机提升了大转矩鼠笼异步调宽电动机的性能。

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.

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, 1 lth, 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.

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.

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.

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。