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1.
回馈式级联型变频器PWM整流控制及其谐波分析 总被引:1,自引:0,他引:1
研究了回馈式H桥级联型多电平变换器,利用移相变压器的二次侧漏抗代替PWM整流器的输入电抗器,采用比例积分加谐振(PIR)的调节方法,设计了电网电压定向控制的PWM整流器双闭环控制策略。同时,文中给出了H桥的功率单元拓扑结构、PWM整流器的数学模型及控制策略,对PIR调节器原理、功率单元及网侧电流谐波进行了分析阐述。通过实验,验证了移相变压器消除谐波的作用,以及控制策略对直流母线电压稳定的有效性,实验结果表明PWM整流器及其控制策略在电动机加速、减速过程中,表现出良好的四象限运行性能。 相似文献
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《Industry Applications, IEEE Transactions on》2006,42(5):1222-1229
This paper presents an algorithm to calculate the current references on line, considering the inherent nonlinear nature of the saturation effect in an interior permanent-magnet synchronous machine for the minimum-copper-loss control under the current and voltage limit of the drive system. This paper basically approaches this issue as a nonlinearly constrained optimization problem where the torque command imposes the nonlinear equality constraint and the voltage limit imposes the nonlinear inequality constraint. Depending on the operating region, it solves the corresponding set of nonlinear equations in real time derived from the Lagrange multiplier method. Newton's method among various techniques is adopted to implement the numerical solution. This scheme gives accurate results not only in motoring but also in generating operation of the machine, since the voltage drop of the stator resistance is taken into account, which is hardly applicable to a two-dimensional lookup table where the inputs are the torque command and the maximum flux amplitude, and the output is each axis current reference in the rotor reference frame. The simulation and experimental results show the feasibility and performance of the proposed technique. 相似文献
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本文提出了一种电动汽车用异步电机的定子磁链弱磁控制方法,通过引入定子参考电压与逆变器能提供的电压值的比较,确定电机的运行区域,进而确定能够输出最大转矩的励磁电流,再结合给定转矩求出定子磁链参考值。本方法采用定子参考电压与母线电压对应值的比较,仅需简单计算即能实现恒转矩、恒功率、降功率区域的平滑过渡。在逆变器和电机的电压、电流能力一定时,能够输出最大转矩。无需转子磁链定向,适用于定子磁链控制的场合。通过动态调整转矩给定限制值可保证电机稳态运行不过流。仿真和实验结果证明了本方法的有效性。 相似文献
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Permanent magnet synchronous motors (PM motors) are widely used in industrial applications. Some applications such as electric vehicles and compressor drives require constant-power operation. The available maximum power under specified voltage and current constraints can be obtained by optimal current vector control, such as maximum torque control and flux-weakening control. The operating limits, however, strongly depend on the machine parameters. This paper examines the relationships between the machine parameters and the output characteristics. It is shown that the power-versus-speed characteristic depends only on the difference between the magnet flux linkage and the maximum flux linkage of the d-axis armature reaction. The maximum torque and the constant-power operating range are obtained as functions of this difference. The optimal machine parameters and the design of PM motors for constant power operation are discussed based on the overall analytical results and on analyses that takes into account both copper loss and core loss in light-load operation. © 1998 Scripta Technica. Electr Eng Jpn, 123(3): 55–63, 1998 相似文献
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The effects of using different input voltage and different core material of different saturation flux density on the switching power converter weight minimization are presented. The design- oriented sensitivity analysis by perturbing the operating point, for example, the input voltage and the maximum flux density, reveals valuable design insights into the switching power converter global design optimization. A cost-effective computer-aided nonlinear programming (NLP) design technique is utilized for the minimum weight design. The new topology Cuk switching converter is taken as a demonstration example. Detailed loss and weight breakdowns as a function of the input voltage and the operating flux density are calculated for the optimum operation. Significant differences of the overall power converter performances are observed by using different input voltages and saturation flux densities. 相似文献
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针对电动汽车用内嵌式永磁同步电机(Interior Permanent Magnet Synchronous Motor, IPMSM)在深度弱磁区域电流、转矩振荡较大,电流调节器易饱和等问题,提出了一种负q轴电流补偿的电压反馈弱磁控制策略。首先介绍了传统电压反馈弱磁控制策略,分析了在深度弱磁区电流、转矩振荡的原因;然后结合最大转矩电压比控制,采用负q轴电流补偿的方法,降低了q轴电流环增益,且系统在深度弱磁区域的电流、转矩振荡得到了明显抑制,提高了系统的稳定性;同时对传统的MTPA控制和id=0控制与两种弱磁方法进行了稳态特性测试。最后通过实验证明了负q轴电流补偿法弱磁控制策略的可行性。 相似文献
7.
Hofmann H. Sanders S.R. Sullivan C.R. 《Industry Applications, IEEE Transactions on》1997,33(4):935-942
In many variable-torque applications of induction machines, it is desirable to operate the machine at high flux levels, thus allowing the machine to produce higher torques. This can lead to saturation of the main flux path, introducing cross-coupling effects which can severely disrupt the performance of controllers dependent on knowledge of the machine's magnetic parameters. Stator flux-oriented torque-control schemes need not depend on the magnetic parameters of the machine and, hence, are potentially more robust and easier to implement in magnetic saturation than rotor-flux-oriented control. In this paper, the authors present and analyze a stator-flux-oriented torque-control scheme. This controller only requires knowledge of the stator voltage, stator current, and stator resistance. An analytical expression for the maximum achievable torque output of the machine using a linear magnetics model is compared with values calculated using a nonlinear magnetics model incorporating saturation of the main flux path and is shown to be a good approximation at high flux levels, when the main flux path is heavily saturated. Experiments carried out on a 3 hp 1800 RPM wound-rotor induction machine show smooth operation of the control scheme at torque levels up to at least four times rated torque 相似文献
8.
A. El Fadili F. Giri A. El Magri G. Besançon 《International Journal of Adaptive Control and Signal Processing》2014,28(2):149-168
This paper addresses the problem of state estimation in induction motors. Generally, the motor observer design has been dealt based on standard models neglecting the saturation effect in the magnetic characteristic. As a matter of fact, magnetic saturation cannot be ignored especially when considering control strategies (speed and torque) that involve large flux variations. Such large flux variations are necessary to meet optimal operation conditions in the presence of wide range load torque changes. On the other hand, it is well known that use of mechanical (speed and torque) sensors entails reliability issues. In this paper, a new sensorless adaptive observer is designed for induction machine based on a model that accounts for the nonlinear feature in the magnetic circuit. The observer consists of two interconnected state‐dependent gain observers and is formally shown to provide accurate estimates of the mechanical and magnetic variables using only stator current and voltage measurements. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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The interior permanent magnet (IPM) synchronous motor is compatible with extended-speed-range constant-power operation by means of flux-weakening control. Flux weakening uses stator current components to counter the fixed-amplitude magnetic airgap flux generated by the rotor magnets, performing a role similar to field weakening in a separately excited dc motor. The nature of current regulator saturation caused by the finite inverter dc source voltage is described, marked by premature torque and power degradation at high speeds in the absence of flux-weakening control. This is followed by presentation of a new flux-weakening control algorithm developed as a modification of an established feedforward IPM torque control algorithm described previously in the literature. Attractive features of this new algorithm include smooth drive transitions into and out of the flux-weakening mode, fast response, as well as automatic adjustment to changes in the dc source voltage. Simulation and empirical test results from a 3-hp laboratory IPM motor drive are used to confirm the constant-power operating envelope achieved using the new flux-weakening control algorithm. 相似文献
13.
Gallegos-Lopez G. Gunawan F.S. Walters J.E. 《Industry Applications, IEEE Transactions on》2005,41(4):1020-1028
This paper presents a novel current regulation algorithm for permanent-magnet ac (PMAC) machines that provides maximum torque-per-ampere capability in the entire field-weakened region. The algorithm provides robust current regulation with maximum efficiency and torque capability for PMAC machines despite significant changes in the voltage source and machine parameters. The algorithm identifies when the current regulator starts to saturate and determines the optimum d-axis current command for the machine. The q-axis current command is determined from the torque command and d-axis current feedback. When the voltage angle reaches the maximum angle, the current magnitude is decreased to provide maximum torque per ampere. Experimental results from a machine prototype show that the algorithm provides good overall dynamic response and smooth transitions into the field-weakened region with maximum torque-per-ampere capability in all four quadrants of operation. 相似文献
14.
异步电机直接转矩控制模糊DSVM控制策略 总被引:1,自引:1,他引:0
针对传统异步电机直接转矩控制系统低速转矩脉动大、电流畸变严重、磁链轨迹内陷以及开关频率不固定等问题,基于离散空间电压矢量调制(DSVM)技术和模糊控制技术,提出了一种改善低速性能的控制策略.利用DSVM技术合成19种电压矢量,使低速区可供选择的电压矢量数目增加,提高了转矩调节器的控制精确度,采用模糊控制器选择电压工作矢量,明显抑制了转矩脉动.仿真结果表明,改进的DSVM控制策略及模糊控制算法的应用,在保证开关频率恒定的前提下,明显克服了低速磁链轨迹内陷、转矩脉动大、电流畸变严重等缺点,有效地改善了直接转矩控制的低速运行性能. 相似文献
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对于同步磁阻电机在运行过程中受到磁路饱和与电压极限的影响,本文提出了最优电流角控制策略。采用Ansoft软件对电机内部磁场进行有限元仿真,对dq轴电感的耦合与饱和现象进行拟合,并利用拟合结果得到最优电流角随负载转矩变化的轨迹,以实现同步磁阻电机最大转矩电流比(MTPA)控制;同时考虑电压、电流极限对电机运行的影响,使电机在高速运行时可以实现空载到满载的稳定运行。通过建立考虑磁路饱和的同步磁阻电机数学模型进行仿真验证,而实验结果也说明了该方案的可行性与有效性。 相似文献
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高转速比异步变频电机电磁设计,既要满足高速弱磁区转矩不足,又要克服低速时磁路过饱和。以1 600 k W异步变频电机为例分析了等效电路参数变动特点,绘制了高低转速下转矩、效率、电压、电流和功率因数曲线;并得出了磁密、磁导率分布图,计算了不同工况下损耗的时间分布图。经电机型式试验测试,设计方案满足技术要求。 相似文献
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考虑到传统直接矢量控制运算量庞大且极易产生饱和漂移和累积误差,经过对转子磁链的分解与近似,研究了一种基于简化模型的感应电机矢量控制方法.该方法通过直接对励磁电流分量和转矩电流分量进行闭环控制,将复杂的电流转电压过程归入PI调节器,简化了感应电机直接矢量控制.实验结果表明.该方法动态抗扰动指标可靠有效,系统编程量少且不易产生饱和振荡. 相似文献
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感应电机的最大转矩电流比(MTPA)控制算法根据需求转矩调节磁链幅值,以达到转矩与定子电流比值的最大化。因磁链随转矩的变化而变化,不再像传统控制算法保持磁场幅值恒定,磁场非线性饱和效应会对控制系统产生影响。针对此问题,该文提出考虑磁饱和特性的MTPA转矩控制系统。根据需求转矩以及饱和模型,通过线性搜索寻找最优磁链目标值,并在计算励磁电流时考虑d轴转子电流的动态特性,用降阶观测器观测转子磁链,并在设计滑模磁链控制器以及反步法设计转矩控制器时考虑观测误差,以确保控制器参数的设置能达到全局稳定。仿真和实验结果证明了所设计控制器的有效性。 相似文献
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A dc motor drive is controlled by varying the armature current and field current. The field is a measure of flux, and the armature current times field current is a measure of torque. Various approximate means of estimating the flux and torque levels in an induction motor exist. Most of these methods are sensitive to motor parameter value changes and do not work well near zero speed. Also, the harmonics in the motor voltage and current due to the nonsinusoidal inverter waveform cause errors in the estimated torque. A practical method has been developed to measure the flux level in an induction motor in the actual operating environment. Using the flux signals and stator current, the actual electromagnetic torque can be obtained. This torque signal responds correctly to motor saturation and inverter voltage waveform harmonics. The motor can be designed to operate without the customarily required flux margin, since the flux level is accurately controlled. The control strategy for use with these feedback signals does not require the use of a tachometer. 相似文献
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Khater Faeka M. H. Lorenz R. D. Novotny D. W. Tang Keith 《Industry Applications, IEEE Transactions on》1987,(2):276-282
The magnitude of rotor flux is a primary design and application variable for field-oriented induction machine controllers. Optimization of a nonsaturating machine controller for peak torque/A will lead to operation at the peak of the constant current torque-versus-slip curve. It is shown how flux level selection for both standard and high efficiency motors is altered by including saturation characteristics. Theoretical and experimental approaches for calculation of flux-producing current in the presence of magnetic saturation are presented. The theoretical method includes a straightforward two-parameter saturation model, which is demonstrated to possess characteristics very close to experimental data. This approach contributes substantial insight to saturated machine analysis while retaining relative simplicity as a design tool. The experimental approaches developed are straightforward and general. 相似文献