Slip-frequency detection for indirect field-oriented control drives

This paper presents a new technique to detect the slip angular frequency in induction motor drives with indirect field-oriented control (IFOC). Slip frequency is calculated by processing the effects exerted by an additional high-frequency signal on the zero-sequence stator voltage. By measuring such a zero-sequence voltage, it is possible to evaluate the air-gap flux and detect the slip frequency in order to implement an IFOC algorithm. According to the proposed approach, rotor time constant errors are not influent as in conventional field-oriented control schemes, thus, complex tuning or compensation techniques are not required. Simulations and experimental tests are performed to evaluate the consistency of the proposed approach.     

间接矩阵变换器-双异步电机调速系统的简化模型预测控制

间接矩阵变换器-双异步电机调速系统开关状态数量多,数学模型复杂,如果采用传统模型预测磁链控制方法,系统计算量巨大,控制频率及开关频率低,导致网侧电能质量和电机调速性能差.针对这一问题,本文提出一种简化的模型预测电压控制(MPVC)方法,以间接矩阵变换器的输入电流和输出电压作为控制目标,对预测模型进行简化,通过状态预筛选...     

Indirect field-oriented control of an induction motor in thefield-weakening region

A self-organized field-oriented induction machine controller that addresses problems encountered in the field-weakening region is presented. The field-oriented controller (FOC) is based on model reference adaptive principles but relies on samples of the state of the machine to determine control inputs. The proposed controller is compared with other approaches to field-weakening operation, and the advantages and limitations of each are discussed. Experimental results are presented for the classical and the self-organized approaches to field-weakening operation     

一种异步电机无速度传感器间接磁场定向控制策略

针对无速度传感器异步电机,提出了一种新的滑模磁通和速度观测方法。实际电流和观测电流之间的误差收敛到零,保证磁通观测器的精确性。根据估计的定子电流和转子磁链来估计转子的转速和转子时间常数。估计的转子时间常数用于滑模计算和观测器结构中,估计的转速用来作为转速调节的反馈。仿真结果证明所提出的速度估算方法有效以及所提出的观测器结构具有鲁棒性。     

A strategy for improving reliability of field-oriented controlledinduction motor drives

Although design of induction motor drives employing field-oriented control has reached a relatively mature state, relatively little effort has been expended on improving the reliability of these drives. A new, improved induction motor drive topology and control strategy are proposed that allow for continuous, disturbance-free operation of the drive even with complete loss of one leg of the inverter or motor phase. A complete analysis and computer simulation of the control and circuit concepts is included     

Speed sensorless field-oriented control of induction motor withrotor resistance adaptation

Several field-oriented induction motor drive methods without rotational transducers have been proposed. These methods have a disadvantage that the rotor resistance variation causes an estimation error of the motor speed. Therefore, simultaneous estimation of the motor speed and the rotor resistance is required. This paper presents a method of estimating simultaneously the motor speed and the rotor resistance of an induction motor by superimposing AC components on the field current command. The validity of the proposed method is verified by simulation and experimentation     

Sensorless control of inverter-fed induction motor drives

Sensorless control is considered to be a lower cost alternative than the position or speed encoder-based control of induction motors. Two popular sensorless control methods, namely, the model reference adaptive system (MRAS) and the Luenberger observer (LO) methods are compared for speed and torque control characteristics. They are also compared against the well-known vector control principle. For the drive system simulated, the torque and speed obtained from sensorless control are almost identical to those obtained from the vector control method. However, the torque ripple for the sensorless methods is observed to be higher than vector control-based method. The MRAS method introduces higher torque ripple when compared to the Luenberger observer. In addition, speed estimation methods employed in sensorless control are more sensitive to motor parameter variations.     

Decoupled direct control for PWM inverter-fed induction motor drives

A new direct torque and stator flux control method is presented for pulsewidth modulation (PWM) inverter-fed induction motors. This new strategy, called decoupled direct control (DDC), is based on a decoupling matrix that allows for the separate control of the stator flux and the torque. This method is compared to the well-known direct field-oriented control (FOC) and stator flux vector control (SFVC) methods. Two DDC-based methods are presented. The first determines the stator voltage vector such that the torque and the flux track their respective reference trajectories in one sampling time. The second sets separately the dynamic behavior of the torque and stator flux errors by the use of proportional-plus integral (PI)-type controllers. These methods take into account the full motor dynamics without the need of a coordinate transformation and reduce significantly computation requirements compared to FOC and SFVC. The two proposed strategies have been implemented experimentally and comparisons with FOC and SFVC were carried out. The obtained results show the effectiveness of the proposed PI-DDC strategy.     

一种新的异步电动机调速系统的混合控制方法

矢量控制(FOC)和直接转矩控制(DTC)是目前高性能异步电动机调速系统中的两种主要控制方法.研究和工程实践表明,这两种方法各有优缺点,国内外很多学者也提出了很多方案,试图改进和完善这两种控制方法.本文从全新的思路出发,尝试把这两种方法结合到一个控制系统中,取长补短,形成一种新的混合控制方法.该方法使用户可以根据实际运行的不同需要,在线灵活地切换到合适的控制方法(FOC或DTC),以提高控制性能.为了实现两种控制方法之间的平滑切换,本文把传统的PI控制器改造成可重置PI控制器.仿真和实验结果表明,这种可重置PI控制器可以有效减少FOC和DTC切换时造成的系统波动,同时能保持原有控制系统的性能,提高了本文提出的混合控制方法的实用价值.     

三相无轴承异步电机的解耦控制系统

为适应无轴承运行控制技术走向高速大功率领域的需要,对三相无轴承异步电机的控制模型、策略和系统进行研究和设计.经理论解析推导出激磁电感模型、基于转矩系统气隙磁链的可控磁悬浮力模型和不稳定单边磁拉力解析式,给出单边磁拉力前馈补偿方法,详细介绍四极转矩控制系统和二极磁悬浮控制系统的结构和控制原理;针对样机进行磁悬浮解耦控制系...     

异步电动机磁场定向前馈解耦控制系统的研究

针对大功率交流传动控制场合，在研讨其实现方案的基础上，就基于前馈解耦控制方式的异步电动机转子磁场定向系统进行了研究。研讨了异步电动机解耦方式与矢量控制系统的结构、影响电机解耦及磁场定向的因素，对转子电阻进行了辨识，并对所述的矢量控制系统方案进行了实验，结果表明，所述控制系统方案可行。     

三相无轴承异步电机的磁场定向控制

为实现三相无轴承异步电机的高性能悬浮和驱动控制,研究了4极转矩系统和2极磁悬浮系统的磁场定向控制问题.首先对转矩系统的气隙磁场定向和转子磁场定向控制进行了对比分析,然后分析了磁悬浮系统的磁场定向控制策略和非定极转子的感应补偿问题;最后,根据三相无轴承异步电机的运行控制特点,转矩系统采用了转子磁场定向、悬浮系统采用了气隙磁场定向和感应补偿的组合控制策略,对三相无轴承异步电机的控制系统进行了仿真和实验分析.结果表明:在额定转速范围内,可实现可靠的悬浮控制和良好的解耦控制性能.所采用的磁场定向控制策略是可行的.     

异步电动机间接磁场定向控制的霍夫分岔分析

定性分析了在异步电动机间接磁场定向控制中,电机时间常数失配度对异步电动机稳定性的影响。观察到,在一定的参数范围内,异步电动机间接磁场定向控制系统会出现霍夫分岔。并推算出系统发生霍夫分岔的条件,及其在该条件下的霍夫分岔点,从而得到设计PI速度环控制器的准则,使系统不发生霍夫分岔。     

Two-phase induction motor drives

This article starts with a presentation of the mathematical model for an asymmetrical two-phase induction motor drives (TPIM). This is followed by an analysis of TPIM behavior under variable frequency supply, with the running capacitor placed or removed from the circuit. This article attempts mainly to investigate the reasons for the lack of variable-speed drives. Consequently, the aptitude of the TPIMs for operating at variable speed is to be estimated and the suitable power electronic topologies identified. The most common form of a typical two-phase machine is the permanent split-capacitor motor (PSCM), usually recognized as the single-phase induction machine.     

一种用于异步电机效率优化的混合搜索方法

针对异步电机效率优化问题,提出了一种混合搜索方法.该方法起始于模糊自适应搜索,然后切换至黄金分割法以获取确定收敛速度.这样的搜索步骤能够降低转矩波动,避免在最优点附近发生振荡.利用一个包含铁损和机械损耗的异步电机模型,对该方法进行了矢量控制下的性能验证.仿真结果验证了该方法的有效性.     

A sensorless variable structure control of induction motor drives

In this paper, an indirect field-oriented induction motor drive with a sliding-mode controller is presented. The design includes rotor speed estimation from measured stator terminal voltages and currents. The estimated speed is used as feedback in an indirect vector control system achieving the speed control without the use of shaft mounted transducers. Stability analysis based on Lyapunov theory is also presented, to guarantee the closed loop stability. The high performance of the proposed control scheme under load disturbances and parameter uncertainties is also demonstrated via simulation examples.     

Sensorless direct field-oriented control of three-phase induction motors based on "Sliding Mode" for washing-machine drive applications

Sensorless direct field-oriented (SDFO) control of three-phase induction motors based on "sliding mode" has been studied and applied to domestic washing-machine drives. In this paper, three related techniques, sliding-mode flux observer, sliding-mode speed controller, and direct rotor-speed estimator are presented for the application of SDFO "sliding mode" in induction-motor control system. Specifically, the investigations focus on how improving speed regulation, system robustness, and some special technical issues in washing-machine drives. The complete control schemes have been developed and implemented in a low-cost digital signal processor-based electronic controller. Through a variety of system performance validation tests, it has been proved that the developed SDFO control not only achieves satisfied steady as well as a dynamic performance, but also is robust for washing-machine driving applications.     

Five-level double converters for induction motor drives

In this article, a PWM control strategy for a three-phase, five-level double converter system is proposed. The proposed method is able to correct the five-level DC potentials, maintain the input power factor at near unity, and achieve adjustable-speed drive. Simulation and experimental results verified the validity of the control strategy. However, large voltage ripples were observed in the experimental results. Further study is needed to develop a control method that can reduce voltage ripples at the DC link capacitors as well as the harmonic distortions of the input and output waveforms