A neural-network-based space-vector PWM controller for athree-level voltage-fed inverter induction motor drive

A neural-network-based implementation of space-vector modulation (SVM) of a three-level voltage-fed inverter is proposed in this paper that fully covers the linear undermodulation region. A neural network has the advantage of very fast implementation of an SVM algorithm, particularly when a dedicated application-specific IC chip is used instead of a digital signal processor (DSP). A three-level inverter has a large number of switching states compared to a two-level inverter and, therefore, the SVM algorithm to be implemented in a neural network is considerably more complex. In the proposed scheme, a three-layer feedforward neural network receives the command voltage and angle information at the input and generates symmetrical pulsewidth modulation waves for the three phases with the help of a single timer and simple logic circuits. The artificial-neural-network (ANN)-based modulator distributes switching states such that neutral-point voltage is balanced in an open-loop manner. The frequency and voltage can be varied from zero to full value in the whole undermodulation range. A simulated DSP-based modulator generates the data which are used to train the network by a backpropagation algorithm in the MATLAB Neural Network Toolbox. The performance of an open-loop volts/Hz speed-controlled induction motor drive has been evaluated with the ANN-based modulator and compared with that of a conventional DSP-based modulator, and shows excellent performance. The modulator can be easily applied to a vector-controlled drive, and its performance can be extended to the overmodulation region     

Investigation of fault modes of voltage-fed inverter system forinduction motor drive

The reliability of power electronics systems is of paramount importance in industrial, commercial, aerospace, and military applications. The knowledge about the fault mode behavior of a converter system is extremely important from the standpoint of improved system design, protection, and fault tolerant control. This paper describes a systematic investigation into the various fault modes of a voltage-fed PWM inverter system for induction motor drives. After identifying all the fault modes, a preliminary mathematical analysis has been made for the key fault types, namely, input supply single line to ground fault, rectifier diode short circuit, inverter transistor base drive open, and inverter transistor short-circuit conditions. The predicted fault performances are then substantiated by simulation study. The study has been used to determine stresses in power circuit components and to evaluate satisfactory post-fault steady-state operating regions. The results are equally useful for better protection system design and easy fault diagnosis. They will be used to improve system reliability by using fault tolerant control     

Analysis of PWM current source GTO inverter with PWM-controlledthyristor rectifier for induction motor drive

With the application of an energy rebound circuit for the pulsewidth modulation (PWM)-controlled rectifier, an improved current source gate turn-off thyristor (GTO) inverter system capable of producing sinusoidal inputs and outputs is presented. The energy rebound circuit in the inverter is used to turn off the thyristors in the rectifier for applying PWM control techniques and also to clamp the spike voltage produced in the inverter circuit. The principles and circuit operations of this system are described in detail, and requirements for PWM control of the rectifier are investigated. The conditions for satisfying the requirements of the energy rebound circuit are analyzed by experimental and theoretical methods. The PWM-controlled current source GTO inverter system is used to drive an eight-pole 400 Hz 5.5 kW induction motor. Analytical and experimental results, as well as the characteristics of the motor drives, are given     

一种用于电机驱动的极谐振ZVT-PWM三相逆变器

提出了一种驱动大功率交流电机的极谐振零电压过渡脉宽调制（RP ZVT－PWM）逆变器的改进电路,并对该电路的ZVT工作过程进行了详细的理论分析。在该电路中,通过辅助开关的控制,使得谐振只发生在主开关状态过渡的瞬间,谐振电容既作为主开关关断时的吸收电容,又在主开关开勇时和谐振电感构成谐振回路,为其提供一个ZVT条件。仿真分析和实验结果验证了逆变桥上主开关的ZVT工作过程及本文所提电路的正确性和可行性。     

DTC异步电机驱动系统中逆变器故障工况研究

为了寻求进行系统可靠性设计的依据,对直接转矩控制异步电机驱动系统中逆变器故障工况进行研究.通过对直接转矩控制原理的分析,指出系统运行工况的影响因素;对逆变器最常见的功率开关短路与开路故障工况进行仿真研究,其中功率开关短路故障工况指系统采取截止故障开关互补开关或截止所有开关两种保护方案之后的工况.仿真结果表明,短路故障后...     

基于PWM逆变器的直线感应电机参数辨识方法

针对直线感应电机初级漏感和次级漏感不相等的特性,提出了一种基于PWM逆变器的直线感应电机参数辨识方法,将堵转试验的等效电路改进后得到方程组计算电机的参数。将此方法应用于一额定电压30V的直线感应电机参数辨识中,试验结果与传统方法得到的试验结果比较,证明了所提出的方法提高了辨识精度。     

A digital signal processor based robust integral-proportional controller for an induction motor servo drive

A digital signal processor (DSP) based computer controlled indirect field oriented induction motor servo drive with robust control characteristics is proposed in this paper. First, the DSP based induction motor servo drive is implemented and the dynamic model of the system at the nominal condition is identified by a curve fitting technique. Based on this model, an integral-proportional controller is quantitatively designed to match the prescribed position tracking specifications. Then a simple robust controller is designed and augmented to reduce the performance degradation due to uncertainties.     

Application of type-2 fuzzy logic controller to an induction motor drive with seven-level diode-clamped inverter and controlled infeed

This paper describes a new control method for the integrated of six current rectifiers—seven-level diode-clamped inverter feeding induction motor considering dc-link capacitors voltage balancing problem. The proposed controller uses type-2 fuzzy systems to compensate the fluctuations of capacitors voltage, draw a sinusoidal line current with nearly unity power factor, and ensure the motor speed control. The performance of dc-link voltages control is evaluated in comparison to the conventional PI control scheme. The overall system and the control algorithm are presented and a set of simulations is carried out in order to prove the good performances of the proposed solution.     

A stator-flux-oriented vector-controlled induction motor drive withspace-vector PWM and flux-vector synthesis by neural networks

A stator-flux-oriented vector-controlled induction motor drive is described where the space-vector pulsewidth modulation (SVM) and stator-flux-vector estimation are implemented by artificial neural networks (ANNs). ANNs, when implemented by dedicated hardware application-specific integrated circuit chips, provide extreme simplification and fast execution for control and feedback signal processing functions in high-performance AC drives. In the proposed project, a feedforward ANN-based SVM, operating at 20 kHz sampling frequency, generates symmetrical pulsewidth modulation (PWM) pulses in both undermodulation and overmodulation regions covering the range from DC (zero frequency) up to square-wave mode at 60 Hz. In addition, a programmable cascaded low-pass filter (PCLPF), that permits DC offset-free stator-flux-vector synthesis at very low frequency using the voltage model, has been implemented by a hybrid neural network which consists of a recurrent neural network (RNN) and a feedforward neural network (FFANN). The RNN-FFANN-based flux estimation is simple, permits faster implementation, and gives superior transient performance when compared with a standard digital-signal-processor-based PCLPF. A 5 HP open-loop volts/Hz-controlled drive incorporating the proposed ANN-based SVM and RNN-FFANN-based flux estimator was initially evaluated in the frequency range of 1.0-58 Hz to validate the performance of SVM and the flux estimator. Next, the complete 5 HP drive with stator-flux-oriented vector control was evaluated extensively using the PWM modulator and flux estimator     

Fuzzy controller for inverter fed induction machines

An induction machine operated with a direct self controller (DSC) shows a sluggish response during startup and under changes of torque command. Fuzzy logic is used in conjunction with direct self control to minimize these problems. A fuzzy logic controller chooses the switching states based on a set of fuzzy variables. Flux position, error in flux magnitude and error in torque are used as fuzzy state variables. Fuzzy rules are determined by observing the vector diagram of flux and currents. The operation of the direct self controller becomes difficult at low speeds due to the effect of change in stator resistance on the flux measurements. To improve the system performance at low speeds a fuzzy resistance estimator is proposed to eliminate the error due to the change in stator resistance. At constant flux and torque commands any change in stator resistance of the induction machines causes an error in stator current. This error is utilized by the fuzzy resistance estimator to correct the stator resistance used by the controller to match the machine resistance. Both a fuzzy controller and fuzzy resistance estimator are simulated for a 3 HP induction motor. The simulation results demonstrate a good performance     

Sensorless induction spindle motor drive using fuzzy neural network speed controller

A sensorless induction spindle motor drive using synchronous PWM and dead-time compensator with fuzzy neural network (FNN) speed controller is proposed in this study for advanced spindle motor applications. First, the operating principles of a new type synchronous PWM technique are described in detail. Then, a speed observer based on the model reference adaptive system (MRAS) theory is adopted to estimate the rotor speed. To increase the accuracy of the estimated speed, the speed estimation algorithm is implemented using a digital signal processor. Moreover, since the control characteristics and motor parameters for high speed operated induction spindle motor drive are time-varying, an FNN speed controller is developed to reduce the influence of parameter uncertainties and external disturbances. In addition, the FNN is trained on-line using a delta adaptation law. Finally, the performance of the proposed sensorless induction spindle motor drive system is demonstrated using some simulation and experimental results.     

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。     

A 7.5 kW ultrasonic inverter motor drive employing MOS-controlledthyristors

The design and performance of an inverter induction motor drive that employs an ultrasonic switching frequency to minimize audible noise is described. The MOS-controlled thyristor (MCT) is a high-speed power semiconductor with the potential for high voltage and current ratings. Distinctive features of the device are discussed relative to inverter topology, gate drive requirements, and fault protection. Since MCT devices of sufficient rating were not available, insulated-gate-bipolar-transistor (GBT) devices were used in the experimental model. MCT and IGBT devices have comparable switching times. The design of a 7.5 kW and 20 kHz inverter is discussed, including a modified pulsewidth modulation (PWM) switching algorithm conducive to microprocessor implementation. The algorithm requires reduced computational and storage requirements over previous PWM methods. Implementation of the algorithm is accomplished by a digital signal processor using the efficient C language. Experimental waveforms are presented     

五桥臂逆变器驱动双异步电机调速系统的调制方法研究

在电力机车、电动汽车以及一些工业应用中,常需要两台或者两台以上的电机并联运行.因此,系统中需要多个逆变器.为了降低成本,针对两台电机独立控制的需求,本文研究了采用五桥臂逆变器拓扑的控制系统,并提出了一种适用于五桥臂逆变器的改进型七段式PWM调制方式.该调制方式基于传统的空间矢量脉宽调制技术,通过将控制周期进行分区来实现...