Performance Improvement of Current Source Inverter-Fed Induction Motor Drives

A high performance variable speed drive system using current source inverter fed induction motor is described. The principle of the drive control is based on the field-orientation method, where the stator current is used as the vector quantity. To improve the system response and to operate smoothly at low speed, a current pulsewidth modulation (PWM) control is provided by means of a feedback loop. This system operates stably and shows a high dynamic performance in a wide range, from zero to rated speed. Dual current source inverter is applied to this drive system which results in a remarkably low copper loss of the motor, even in PWM operation.     

Analysis of PWM GTO Current Source Inverter-Fed Induction Motor Drive System

A GTO current source inverter which consists of six main GTO's, two auxiliary GTO's, and three capacitors is presented. This inverter can supply both the sinusoidal voltage and current to the motor by pulsewidth modulation (PWM) techniques. The normal PWM pattern produced by two control signals with the carrier and the modulating waves and the optimal PWM pattern determined by the harmonic analysis are described. The experimental waveforms for 2.2-kW induction motor drives are given and the circuit operation of this inverter in the PWM technique is clearly shown. In addition, the steady-state characteristics of this inverter-induction motor drive system are analyzed by the state-variable methods, and a close agreement between the analyzed and the experimental waveforms is obtained. It is shown that the harmonic components are eliminated or reduced by using the optimal PWM pattern, and the new inverter with sinusoidal current and voltage is very excellent for ac motor drive.     

变频调速异步电动机效率优化控制的研究进展

异步电动机运行于额定工作点附近时效率较高,轻载运行时其效率会明显下降.优化变频调速异步电动机的效率对于节约能源、系统自身冷却和控制环境污染具有重要意义.总结近年来变频调速异步电动机效率优化控制策略的研究现状,包括基于模型的最优励磁控制、最小输入功率在线搜索法和最小定子电流控制等,分析了各种效率优化控制策略的性能和优缺点,指出变频调速异步电机效率优化研究的发展方向,并给出考虑电机动态响应的效率优化控制研究结果.     

通用变频器-感应电机系统的电机耗能型制动控制方法

利用感应电动机内部损耗进行制动的方法受到了越来越多的重视,本文分析了该方案的数学模型,提出了物理实现的约束条件和具体的控制方案.仿真和实验结果表明采用该控制算法可以有效的对电机进行快速制动,同时由转子侧回馈的能量几乎全部消耗在电机的定转子电阻上,使系统在满足功.能要求的同时,能够一直处于安全的工作状态.该方法可用于各种需要快速制动的"通用变频器 感应电机"系统.     

Control Characteristics of Inverter-Fed Induction Motor

Efficient use of an inverter-fed induction motor drive necessitates a knowledge of the characteristics of the induction motor from a " control" point of view. The characteristics of both the voltage -and the current-source inverter-fed induction motor drive are investigated, neglecting the filter time constants in the link and feedback loops. Of particular interest is the role played by the voltage/current and frequency inputs. Their effects on variables that are not often discussed such as torque angle, stator real power, airgap flux- linkages and stator and rotor voltages/currents are studied. A by- product of this aspect of the study leads to the nature of feedback signals and their suitability for control purposes. It is also found that the link filter has little effect on relative suitability of these signals. A study of the current source induction motor drive dynamics for torque angle feedback is included.     

A Method of Sensing Line Voltages for Parameter Adaptation of Inverter-Fed Induction Motor Servo Drives

Most high-performance inverter-fed induction motor drive systems require signals corresponding to the input voltages of the motor for parameter adaptation. Low-performance systems require the signals for stabilization. The voltage signals are used in the controller circuit and therefore require isolation. Isolation of the voltage signals is not a cost-effective solution in low-power motor drive systems. The fact that the base drive signals to the transistor inverter are isolated makes them the ideal choice for the reconstruction of the motor line voltages. A method of sensing line voltages from the base drive signals of the transistor inverter circuit is described. A step-by-step derivation of the voltage sensing algorithm is given which leads to a simple realization. The synthesized voltages are used in parameter adaptation for inverter-fed induction motor drives. The sensing scheme has been implemented on a laboratory prototype, providing experimental results which are presented.     

A Discrete Feedback Suboptimal Control for Induction Motor Drives

An approach is presented which simplifies the problem of applying optimal control techniques to frequency controlled induction motor drives. This approach consists of subdividing the optimization problem in two subproblems, the solution of which is less difficult than that of the global problem. The controller is obtained by using a discrete-time model for the motor electromagnetic circuits. This has made it possible to take into account both the discretization introduced by the inverter and the computation delay due to the microcomputer-based controller.     

Current Controller for Autocommissioned Vector-Controlled Induction Motor Drives

A current controller composed of a current regulator associated to a parameter adaptation scheme is proposed. The current regulator considers the inherent coupled structure of the induction machine. The adaptive block is coupled to this regulator in order to carry out a high performance current control with low sensitivity to parameter variations. It is shown that this controller can also be used to estimate the machine saturation characteristic and the rotor time constant as part of an indirect vector control autocommissioning procedure. A discrete time approach is utilized for the design considering microprocessor implementation.     

感应电机的逆系统方法解耦控制

针对感应电机这一多变量、非线性、强耦合的控制对象,应用逆系统方法,将感应电机转速与转子磁链解耦成2个二阶子系统。在此基础上,运用线性系统理论对其进行控制。仿真结果表明这种基于逆系统方法的反馈线性化控制策略可实现感应电机的高性能控制。     

基于简单占空比调节的异步电机直接转矩控制

针对异步电机传统直接转矩控制(DTC)存在的转矩脉动大、开关频率不固定等问题,已经提出了一些通过优化有效电压矢量占空比来减小转矩脉动的方法。然而,这些方法不仅计算复杂而且对参数依赖性大。本文在比较三种经典占空比控制方法性能的基础上,提出一种简单有效的占空比确定方法。该方法能同时减小转矩和磁链脉动,并且尽可能保持了传统DTC结构简单和鲁棒性强的优点。仿真和实验结果验证了本文所提方法的有效性。     

Integral Variable Structure Controller for Current Control of PWM Inverter-Fed AC Drives

A new current control technique is presented for three-phase PWM inverterfed AC drives. The features of several existing approaches are analyzed and an integral variable structure control (IVSC) is proposed as an effective way of realizing the high-performance current control. The characteristics of the proposed IVSC are investigated and the design method is presented for the AC drives associated with a voltage-fed PWM inverter. By employing the proposed control, a robust control performance against the parameter uncertainties is obtained in both transient and steady states. The proposed control is applied to the three-phase induction motor drives and the performance improvement is well demonstrated through the simulations and experiments.     

DC Link Filter Design Considerations in Three-Phase Voltage Source Inverter-Fed Induction Motor Drive System

The dc link filter elements in a three-phase voltage source inverter-fed induction motor system can affect the performance of the drive system if not properly chosen. The requirements, design considerations, and a simplified procedure for the selection of filter component values based on minimization of voltage and current ripple currents in the dc link, damping effects, and on resonant frequency considerations are formulated. Typical computational results and experimental waveforms are presented.     

异步电机无速度传感器矢量控制

对异步电机无速度传感器矢量控制进行了综述，介绍了开环速度估计、模型参考自适应系统、观测器估计、人工智能方法估计、空间饱和定子三次谐波电压估计、电机凸极效应估计等常见的速度估计方法，指出了各自的优缺点和适用范围。今后这方面的研究应注重于提高速度估计的精度、改进低速区控制性能以及提高系统的抗干抗能力和参数的鲁棒性。     

感应电机模型预测磁链控制

模型预测控制(model predictive control,MPC)具有原理简单、多变量控制和容易处理非线性约束等优点,是近年来在电力电子与电力传动领域受到广泛关注和研究的一种控制方法。MPC一般基于最小化目标函数的原则来实现系统的优化控制,但当目标函数中控制变量的量纲不一致时,需要设计相应的权重系数来实现对多个变量的同时控制。以感应电机的磁链和转矩控制为例,由于目前尚缺乏通用的理论设计方法来确定磁链和转矩的权重系数,为保证调速系统在不同的运行点具有良好的动静态性能,在实际应用中需要通过大量的仿真或实验来确定权重系数的大小。为此,提出一种适用于感应电机控制的改进MPC。通过深入推导磁链和转矩之间的解析关系,将定子磁链幅值和电磁转矩的同时控制转换为等效的定子磁链矢量的控制,从而消除了传统方法中繁琐的权重设计,而且算法简单,容易实现。此外,文中还对数字控制延迟进行了补偿,并且采用预励磁的方法来增大起动转矩,并减小起动电流。最后,在两电平逆变器感应电机平台上进行了仿真和实验,结果表明所提方法在很宽的速度范围内都有良好的性能。     

感应电机电流环非线性积分滑模控制策略

滑模控制器能有效提升感应电机电流环鲁棒性,然而传统滑模控制存在严重的抖振问题,虽然通过引入趋近律能有效降低系统抖振,但仍无法实现系统在有限时间内收敛.为此,该文提出一种感应电机非线性积分滑模电流控制器,在削弱系统抖振的同时,实现了定子电流误差在有限时间内收敛.首先,设计非线性积分滑模面,有效避免了传统积分滑模面中初始误...     

异步电机无速度传感器矢量控制

对异步电机无速度传感器矢量控制进行了综述,介绍了开环速度估计、模型参考自适应系统、观测器估计、人工智能方法估计、空间饱和定子三次谐波电压估计、电机凸极效应估计等常见的速度估计方法,指出了各自的优缺点和适用范围.今后这方面的研究应注重于提高速度估计的精度、改进低速区控制性能以及提高系统的抗干抗能力和参数的鲁棒性.     

A Modified Control Method for Fast-Response Current Source Inverter Drives

The factors which influence the current response to a current command for a normal autosequentially commutated current link inverter (ASCI) are discussed. A simple new method of notching the output current waveform for the ASCI is presented, which is used to control the ac output current from the ASCI. To demonstrate the improvement in the current response of the ASCI with notching (or NASCI), two typical classes of control systems of ac induction machine drives are considered. A performance comparison is made between ASCI and NASCI induction machine drives. Analysis and analog computer simulation results show that substantial improvement in dynamic response is achieved when the notching is utilized.     

电动汽车异步电机变频驱动系统的自抗扰控制

电动汽车异步电机电驱动系统通常采用效率优化策略以节约电能,但效率优化异步电机变频驱动系统存在磁链、负载变化以及电机参数时变等多种不确定因素,对闭环系统的控制器设计提出了较高的要求.为提高电驱动系统的运行性能,设计了效率优化异步电机变频驱动系统的自抗扰控制器,根据在不同负载时电机磁链变化大的特点,给出了自抗扰控制器的参数整定方案.实验结果表明,采用自抗扰控制器的效率优化异步电机变频驱动系统与传统的采用PI调节器的效率优化异步电机变频驱动系统相比,具有更好的抗干扰性能和快速的转速跟踪性能.     

感应电机的无速度传感器逆解耦控制

提出了一种基于扩展的Kalman滤波器的感应电机无速度传感器逆解耦控制方法.首先采用逆系统方法将感应电机的转速与转子磁链进行动态解耦,其次由扩展的Kalman滤波器(EKF)对转速及转子磁链进行实时估计,最后由线性综合方法设计转速和转子磁链闭环调节器,从而实现感应电机的无速度传感器逆解耦控制.仿真结果表明EKF可在整个调速范围内进行高精度的转速和磁链估计,系统具有优良的动态和稳态控制性能