A modified direct torque control for induction motor sensorlessdrive

Direct torque control (DTC) is known to produce quick and robust response in AC drives. However, during steady state, notable torque, flux and current pulsations occur. They are reflected in speed estimation, speed response, and also in increased acoustical noise. This paper introduces a new direct torque and flux control based on space-vector modulation (DTC-SVM) for induction motor sensorless drives. It is able to reduce the acoustical noise, the torque, flux, current, and speed pulsations during steady state. The DTC transient merits are preserved, while better quality steady-state performance is produced in sensorless implementation for a wide speed range. The flux and torque estimator is presented and an improved voltage-current model speed observer is introduced. The proposed control topologies, simulations, implementation data, and test results with DTC and DTC-SVM are given and discussed. It is concluded that the proposed control topology produces better results for steady-state operation than the classical DTC     

Rotor field oriented control strategy with harmonic currents closed-loop control for five-phase induction motor

In order to solve the problems of harmonic currents in the conventional vector control of multiphase induction motor, the rotor field oriented control (RFOC) strategy with harmonic current closed-loop control is proposed in the paper. Based on the transform theory of the multiphase system and the RFOC strategy of three-phase induction motor, the mathematical modulation of RFOC for five-phase induction motor is modeled. The fundamental current and the second order harmonic current can be controlled independently after being decoupled. The proposed strategy is implemented with a board microcomputer that uses TMS320F28335 DSP. The experimental results show that the proposed RFOC strategy with harmonic current closed-loop control has outstanding dynamic and static performance.     

Passivity based control for induction motor drives with voltage-fed and current-fed inverters

In recent years, passivity based control (PBC) scheme has gained wide attention among various nonlinear control methods. Based on Euler–Lagrange equations of motion, controllers are designed from an energy point of view. In this paper, the PBC is applied to induction motor (IM) speed drives with voltage-fed and current-fed inverters, respectively. The stability of the overall system for the voltage-fed IM drive has been verified rigorously, but it lacks for the current-fed IM drive. However, the controller structure of the latter is simpler than that of the former. Experimental results show that the PBC scheme is successful in speed control application for both IM drives. There is no significant differences between two IM drives. The overall system exhibits good robust performances in presence of motor parameter variations and load disturbances.     

Modified direct torque control method for induction motor drives based on amplitude and angle control of stator flux

This paper proposes design and implementation of a direct torque controlled induction motor drive system. The method is based on control of separation between amplitude and angle of reference stator flux for determining reference stator voltage vector in generating PWM output voltage for induction motors. The objective is to reduce electromagnetic torque ripple and stator flux droop which result in a decrease in current distortion in steady-state condition. In addition, the proposed technique provides simplicity of a control system. The direct torque control is based on the relationship between instantaneous slip angular frequency and rotor angular frequency in adjustment of the reference stator flux angle. The amplitude of the reference stator flux is always kept constant at rated value. The system has been implemented to verify its capability such as torque and stator flux responses, stator phase current distortion both during dynamic and steady state with load variation, and low speed operation.     

数字化有限转角力矩电机控制技术

本文提出了某燃油阀门的有限转角数字化控制系统设计方案。从控制的角度详细阐述了有限转角力矩电机电流、速度、位置三闭环控制系统设计,详细介绍了控制系统的硬件设计、控制环路设计以及软件时序设计。对其进行仿真计算,同时对样机产品进行了阶跃、扫频、跟随等性能测试,试验结果表明该数字化控制系统具有重要的实用价值。     

关于异步电机直接力矩控制的研究

直接力矩控制是交流调速中一种新颖、有效的控制方法。首先介绍了异步电机的数学模型 ,在此基础上对直接力矩控制进行了理论分析 ,并介绍其磁通、力矩控制方法 ,给出磁通观测器和力矩观测器 ,同时也对无速度传感器的直接力矩控制作了简要介绍     

感应电机直接转矩控制系统

为了确定影响感应电机直接转矩控制系统稳态性能的主要因素,使用自己开发的仿真软件包进行了仿真实验分析,指出了定子电阻、磁链滞环容差和转矩滞环容差是影响感应电机直接转矩控制系统性能的三个主要因素.定子电阻主要对磁链轨迹影响较大,磁链滞环容差和转矩滞环容差主要影响定子电流谐波和电机转矩,并提出了一些补偿措施.这些结论为进一步改进系统性能提供了一些依据.     

一种无差拍直接转矩控制方法

针对现有的感应电动机无差拍直接转矩控制方法计算比较复杂,且计算得到的两个控制电压与控制对象磁链和转矩不是一一对应的问题,提出了一种在定子磁场定向的同步旋转坐标系下进行无差拍直接转矩控制计算方法.由d轴磁链方程推导出磁链无差拍控制电压的计算式;利用和定子磁链相垂直的q轴电流方程,推导出转矩控制电压计算式.计算出的电压矢量由空间电压矢量脉宽调制方法实现.这种方法计算简单,不需要解二次方程,分离的磁链和转矩控制计算有利于控制安排.对采用这种方法的直接转矩控制系统进行仿真表明,系统转矩控制和磁链控制响应快,对参数的变化不敏感.     

一种无速度传感器的直接转矩控制方案

基于以电机定子电流和定子磁链为状态变量的状态方程的推导 ,提出了一种速度自适应磁链观测器 ,实现了定子磁链和转速的估计 ;用在无速度传感器直接转矩控制系统中 ,具有一定的实用价值。     

A new microcomputer-based direct torque control system forthree-phase induction motor

A microcomputer-based direct primary flux and torque control system for three-phase induction motors is presented, showing that the instantaneous primary flux of the induction motor can be calculated by means of computer software. It is shown that, by selecting a space nonzero voltage vector and its time width, the amplitude of primary flux can be controlled, and that, by selecting a space zero voltage vector and its time width, the amplitude of electromagnetic torque also can be controlled. Therefore, flux and torque control can be achieved separately. The control algorithm can be implemented online with a 1 kB ROM memory. The controller, therefore, can be quite compact, and the hardware and software implementations are easy to achieve. A fully digital controller with a 16 b microcomputer is developed. The experimental results are presented and agree with the theory     

异步电动机无速度传感器的矢量控制

对交流异步电动机无速度传感器的矢量控制进行了综述 ,分析了几种控制方案的原理 ,指出了它们各自的优点与不足 ,并就今后的研究发展方向提出了一些设想     

High-performance direct torque control of an induction motor

A novel direct torque control method for an induction motor is presented which is quite different from field-oriented control. Improving the torque response of a large-capacity induction motor using two sets of three-phase inverters and an open-data induction motor is of special concern. Instantaneous voltage vectors applied by an inverter have redundancy characteristics which provide some flexibility for selecting the inverter switching modes. By using this switching freedom, control is achieved according to the following priorities: (1) high-speed torque control; (2) regulation of the primary flux; (3) decreasing the zero phase sequence current; and (4) minimization of the inverter switching frequency. Simulations and experiments have been carried out to verify the feasibility of this priority control, accompanied by comparisons with another control scheme. Torque frequency-response corner frequencies above 2000 Hz have been experimentally measured, and time constants of 4 ms have been achieved for rotor-speed step responses from -500 to 500 r/min. The peak transient torque during the step change is about 20 times the rate torque     

A novel startup scheme of stator-flux-oriented vector-controlled induction motor drive without torque jerk

This paper proposes a novel zero-speed startup scheme of a stator-flux-oriented speed-sensorless vector-controlled induction motor drive that does not generate any torque jerk. A programmable cascaded three-stage low-pass filter (LPF) method is used for flux vector estimation. Usually, a torque jerk is generated at the vector control transition due to time delay in developing the stator flux by the three-stage LPF. At standstill condition, an algorithm is derived that calculates the stator flux using only the stator currents. A feedforward control strategy of the stator flux is developed to eliminate the torque jerk during transition from the standstill mode to the vector control mode. The performance of the newly developed startup scheme has been verified by simulation and then experimentally on a 3-hp induction motor drive, where the control was implemented by a 32-bit TMS320C30-type digital signal processor. The performance of the drive was found to be excellent in both simulation and experiment.     

Direct torque control, induction motor vector control without anencoder

The basic evolution of direct torque control from other drive types is explained. Qualitative comparisons with other drives are included. The basic concepts behind direct torque control are clarified. An explanation of direct self control and the field-orientation concepts implemented in the adaptive motor model block is presented. The reliance of the control method on fast processing techniques is stressed. The theoretical foundations for the control concept are provided in summary format. Information on the ancillary control blocks outside the basic direct torque control is given. The implementation of special functions directly related to the control approach is described. Finally, performance data from an actual system are presented     

感应电机直接转矩控制系统的转矩脉动极小化方法

针对感应电机直接转矩控制系统在稳态运行时转矩脉动大的问题,提出了一种转矩脉动抑制方法。基于离散化的感应电机模型,分析了直接转矩控制系统的转矩脉动机理。以转矩误差均方根极小为目标,将采样周期分为非零电压矢量作用时间段和零电压矢量作用时间段,推导了最优电压矢量切换时间的计算公式。仿真和实验结果表明所提方法可有效减小直接转矩控制系统的转矩脉动。     

感应电机空间矢量直接转矩控制系统的效率优化

提出了一种感应电机空间矢量直接转矩控制系统的效率最优控制方法。在定子磁链定向坐标系中,建立了计及铁芯损耗的感应电机数学模型。分析了电机损耗与转矩、转速和定子磁链的关系,推导出了不同运行工况条件下效率最优的定子磁链幅值表达式,实现了感应电机直接转矩变频调速系统的效率最优控制。实验结果表明,所提优化控制策略,在保持直接转矩控制快速动态响应特性的同时,可有效提高电机轻载时的运行效率。     

Sensorless induction motor torque and rotation frequency control system

A sensorless induction motor torque and rotation frequency control system with decoupled stator flux linkage and electromagnetic torque control is proposed. Results are presented of simulation modeling of an induction motor drive, and the advantages of the control system developed, namely, its simplicity of implementation and high dynamic performance, are shown.     

基于SVPWM五相感应电机直接转矩控制研究

针对感应电机直接转矩控制(DTC)采用开关表的滞环方法时,存在电流和转矩脉动等问题,提出在DTC中应用空间矢量脉宽调制(SVPWM)的方法。根据五相感应电机模型和DTC基本原理,推导出参考电压矢量。分析了五相逆变器的空间电压矢量,并从中选取出22个有效电压矢量,根据最近四矢量SVPWM算法,计算出第k扇区中工作电压矢量的作用时间。建立了基于双DSP控制的实验系统,实验结果表明,该方法减小了电流和转矩脉动,具有良好的稳态和动态性能。     

双级矩阵变换器驱动异步电机直接转矩控制

在深入分析双级矩阵变换器整流级调制算法和逆变级直接转矩控制策略的基础上,提出了采用双级矩阵变换器驱动异步电机直接转矩控制的策略。换流方式采用零电流换流的思想,即整流级换流前后,在逆变级插入零开关状态,可以保证整流级的零电流换流。此控制策略结合了双级矩阵变换器和直接转矩控制的优点,功率因数可调且具有良好的动静态性能。仿真结果验证了该控制策略的可行性和有效性,表明该策略具有与直流调速系统相媲美的调速性能。     

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.