斩波串级调速系统功率因数的分析与计算

本文简要介绍斩波串级调速系统的原理。指出比传统调速方式的优势所在。重点分析斩波串级调速系统的功率因数。考虑电机激磁电流,整流器和逆变器的换向重叠角对系统功率因数的影响,得出斩波串级调速系统系统功率因数的计算方法。利用华拿东方有限公司提供的实物装置对计算结果进行验证,结果证实了该计算过程的可行性。     

新型转子变频调速装置分析与设计

随着社会发展和节能意识的增强,变频器的市场需求逐渐增大,对变频调速技术的发展要求也越来越高。本文主要介绍了转子变频调速的优点,同时针对传统转子变频调速系统出现的逆变颠覆问题,提出了新型超大功率转子变频装置,即主要在传统串调加斩波的基础上,将逆变部分的晶闸管换成IGBT器件,整个调速装置就成了一个带斩波的IGBT电压型变频器。结果表明,设备可靠性大幅提升,调速精度高,调速范围宽。     

开关磁阻电机变角度电压斩波控制实现方法研究

电压斩波、变角度控制,是开关磁阻电机两种基本的控制方式。变角度电压斩波控制结合了两种控制方式的优点,可优化开关磁阻电机调速系统的效率。角度位置传感器的安装是实现角度位置控制及电机四象限运行的关键,并提出了角度细分软件设计方法。提出了变角度与模糊电压斩波控制相结合的原理及实现方法,最终在dsPIC单片机上实现,验证了该方法的有效性。     

基于状态空间平均法的4MW斩波串级调速系统的研究

本文讨论的是一种DC-DC升压斩波电路模型,应用于4MW电动机斩波串级调速系统中。解决了4MW电机斩波串级调速控制系统的设计问题。该模型基于一种状态空间平均法,包括绝缘栅双极型晶体管(IGBT)和续流二极管(FWD)。实验表明,相比于传统串级调速系统,该控制系统可靠稳定。静态特性和动态特性更好,功率因数也更高。工业生产中。采用这种控制系统的几批设备普遍运行良好,节能效果显著。     

小李学异步电动机(十九) 第六章 异步电动机的调速(非变频)

(接上期)6.5异步电动机的串级调速根据张老师的要求,小李对异步电动机的串级调速进行了预习。但显然,他有点信心不足。他说:"串级调速的原理倒是容易理解的。6.5.1基本原理(1)基本思路绕线转子异步电动机改变转子电流的方法,除了在转子回路里串联电阻外,还可以通过串联一个附加电动势EK来实现,如图6-18a所示。因为转子电流的频率是随转速的变化而变化的,所以,要求附加电动势的频     

IPC变频回馈电控系统在矿井绞车上的应用

本文主要介绍了IPC起重行业变频回馈电控系统在矿井绞车上的应用。变频回馈电控系统是对矿井绞车提升机构原有的绕线式电机转子串电阻调速控制方式进行升级改造的电气系统,采用加能公司PH7系列起重专用变频器对提升电机进行变频控制,同时采用加能公司PFH重型回馈装置将提升电机再生发电状态下产生的再生能量回馈到电网。     

高频斩波串级调速系统在水泥厂的应用

高频斩波串级调速系统是应用于高压大容量异步电动机节能调速领域的一种比较先进的调速系统。本文介绍了水泥厂风机应用高频斩波串级调述系统的技术经济分析。     

PLC在矿井提升机变频调速控制系统中的应用

矿井提升机是矿山生产最重要的设备。传统提升机转子串电阻调速电控系统存在诸多问题,如控制方式繁琐、可靠性低、调速性能差等。针对这种情况采用PLC与变频器相结合的控制方案对原有电控系统进行改造,提高整个电控系统安全可靠性、控制精度及调速性能。     

基于单片机的5-32吨天车遥控装置的设计

本文利用Nordic VLSI公司nRF903发射单元和PHILIPS公司P89LPC932 Flash单片机,实现了高可靠性的无线遥控,研制开发出应用于工业天车上的具有高可靠性的无线遥控装置.由于采用了nRF903发射单元,可以选择信道,特别适用于在同一个环境下有几部天车的情形.该装置主要针对于5-32吨天车电机的转子串多级电阻调速的方案设计的.至于其它类型的天车,电机的转子串电阻调速的方案,只需稍加改动软件设计即可达到遥控的目的.本设计对于其他设备的控制以及家庭使用,有较好的扩展性.     

转子变频调速器发生逆变颠覆的解析

为了解决风机、水泵类的高压电机能耗过高的问题,国内许多厂家都采用转子侧变频调速的方法,主要是将高压电机转子电压进行全桥整流,然后通过IGBT斩波升压后再通过晶闸管逆变桥,将转差功率反馈回到电网实现电能的循环利用,从而达到节能的目的。本文通过对转子变频调速器发生逆变颠覆进行解析,阐述了设计过程中避免转子变频调速器发生逆变颠覆的相关措施,可以有效解决转子变频调速器现场长期运行的稳定性。     

Online Stator and Rotor Resistance Estimation Scheme Using Artificial Neural Networks for Vector Controlled Speed Sensorless Induction Motor Drive

This paper presents a new method of online estimation for the stator and rotor resistances of the induction motor for speed sensorless indirect vector controlled drives, using artificial neural networks. The error between the rotor flux linkages based on a neural network model and a voltage model is back propagated to adjust the weights of the neural network model for the rotor resistance estimation. For the stator resistance estimation, the error between the measured stator current and the estimated stator current using neural network is back propagated to adjust the weights of the neural network. The rotor speed is synthesized from the induction motor state equations. The performance of the stator and rotor resistance estimators and torque and flux responses of the drive, together with these estimators, are investigated with the help of simulations for variations in the stator and rotor resistances from their nominal values. Both resistances are estimated experimentally, using the proposed neural network in a vector controlled induction motor drive. Data on tracking performances of these estimators are presented. With this speed sensorless approach, the rotor resistance estimation was made insensitive to the stator resistance variations both in simulation and experiment. The accuracy of the estimated speed achieved experimentally, without the speed sensor clearly demonstrates the reliable and high-performance operation of the drive     

Field oriented control of induction machines employing rotor endring current detection

The usual method of induction motor torque control uses the indirect field orientation principle in which the rotor speed is sensed and slip frequency is added to form the stator impressed frequency. Unfortunately, the rotor resistance varies as the motor heats up under load thereby changing the rotor time constant which has a deleterious effect on the torque response. In this paper two new field oriented control schemes are presented which employ rotor end ring current detection and thereby remove the dependence of the controller accuracy on temperature so that the controller is entirely independent of rotor time constant variations. The field orientation schemes do not require an incremental encoder for rotor position sensing. The motor torque can be accurately controlled even down to zero speed operation     

A novel DC chopper drive for a single-phase induction motor

The paper presents a new drive for single-phase induction motors. This drive employs a DC chopper circuit with a diode bridge rectifier connected with the stator in a nonconventional fashion. The speed of the single-phase induction motor is controlled by controlling the chopping frequency of the chopper switch. The attractive feature of the drive is that it effects both frequency and phase-angle control simultaneously. The drive performance has received both theoretical and experimental investigation     

Control of induction motors for both high dynamic performance andhigh power efficiency

The authors attempt to control induction motors with maximum power efficiency as well as high dynamic performance by means of decoupling of motor speed (or motor torque) and rotor flux. For maximum power efficiency, the squared rotor flux is adjusted according to a minimum power search algorithm until the measured power input reaches the minimum. Since the motor speed is dynamically decoupled from the rotor flux, this can be done successfully without any degradation of motor speed responses. The controller depends on rotor resistance but not on stator resistance. However, the performance of the control scheme is robust with respect to variations in rotor resistance because an identification algorithm for rotor resistance is employed. The identification algorithm for rotor resistance has some advantages over the previous methods. To demonstrate the practical significance of the results, some experimental results are presented     

An online identification method for both stator-and rotorresistances of induction motors without rotational transducers

This paper describes an effective online method for identifying both stator and rotor resistances, which is useful in robust speed control of induction motors without rotational transducers. The identification method for stator resistance is derived from the steady-state equations of induction motor dynamics. On the other hand, the identification method for rotor resistance is based on the linearly perturbed equations of induction motor dynamics about the operating point. The identification method for both stator and rotor resistances uses only the information of stator currents and voltages. It can provide fairly good identification accuracy regardless of load conditions and be easily incorporated into any sensorless speed controller proposed in the prior literature. Some experimental results are presented to demonstrate the practical use of the identification method. A sensorless speed control system has been built for experimental work, in which all algorithms for identification and control are implemented on a digital signal processor. The experimental results confirm that the proposed method allows for high-precision speed control of commercially available induction motors without rotational transducers     

Speed-sensorless sliding-mode torque control of an induction motor

Novel induction motor control optimizing both torque response and efficiency is proposed in the paper. The main contribution of the paper is a new structure of rotor flux observer aimed at the speed-sensorless operation of an induction machine servo drive at both low and high speed, where rapid speed changes can occur. The control differs from the conventional field-oriented control. Stator and rotor flux in stator fixed coordinates are controlled instead of the stator current components in rotor field coordinates i_sd and i_sq. In principle, the proposed method is based on driving the stator flux toward the reference stator flux vector defined by the input command, which are the reference torque and the reference rotor flux. The magnitude and orientation angle of the rotor flux of the induction motor are determined by the output of the closed-loop rotor flux observer based on sliding-mode control and Lyapunov theory. Simulations and experimental tests are provided to evaluate the consistency and performance of the proposed control technique     

Reduction of vibration and acoustic noise in induction motor drivenby three phase PWM AC chopper using static induction transistors

A three-phase pulse-width-modulated (PWM) chopper that uses a static induction transistor (SIT) to chop the three-phase AC voltage with a 20 kHz carrier frequency and control an induction motor is proposed. Harmonic components in the voltage and current waveforms do not appear in the audio frequency band with this method. When each terminal of the motor is connected to a 4 μF capacitor, the terminal voltage and line current waveforms are almost sinusoidal. The motor speed is controlled by changing the on-time width of the gate signal. The power spectrum of the chopper-driven motor is calculated using a fast Fourier transform and measured. The results are used to reduce vibration and acoustic noise in the motor, which is confirmed by measurement     

A high-performance sensorless indirect stator flux orientation control of induction motor drive

A new method for the implementation of a sensorless indirect stator-flux-oriented control (ISFOC) of induction motor drives with stator resistance tuning is proposed in this paper. The proposed method for the estimation of speed and stator resistance is based only on measurement of stator currents. The error of the measured q-axis current from its reference value feeds the proportional plus integral (PI) controller, the output of which is the estimated slip frequency. It is subtracted from the synchronous angular frequency, which is obtained from the output integral plus proportional (IP) rotor speed controller, to have the estimated rotor speed. For current regulation, this paper proposes a conventional PI controller with feedforward compensation terms in the synchronous frame. Owing to its advantages, an IP controller is used for rotor speed regulation. Stator resistance updating is based on the measured and reference d-axis stator current of an induction motor on d-q frame synchronously rotating with the stator flux vector. Experimental results for a 3-kW induction motor are presented and analyzed by using a dSpace system with DS1102 controller board based on the digital signal processor (DSP) TMS320C31. Digital simulation and experimental results are presented to show the improvement in performance of the proposed method.