Showing papers in "IEEE Transactions on Industry Applications in 1994"

Speed sensorless vector control of induction motor using extended Kalman filter

Abstract: A vector control of an induction motor by an estimated speed using an extended Kalman filter is proposed. With this method, the states are composed of stator current and rotor flux. The rotor speed is regarded as a parameter, and the composite states consist of the original states and the rotor speed. The extended Kalman filter is employed to identify the speed of an induction motor and rotor flux based on the measured quantities such as stator currents and DC link voltage. The estimated speed is used for vector control and overall speed control. Since the current control is performed at a synchronous rotating reference frame, the estimated speed information is also used for the reference frame transformation of the current controller. Computer simulations and experiments of the speed control have been carried out to test the usefulness of the speed estimation algorithm. The experimental results show that the performance of the speed estimation is very good. >

Effects and Compensation of Magnetic Saturation in Flux-Weakening Controlled Permanent Magnet Synchronous Motor Drives

Abstract: Permanent magnet synchronous (PM) motors can be applied to applications requiring constant power operation, such as traction and spindle drives by means of flux-weakening control. In a PM motor drive system with flux-weakening control, the motor parameters are used to produce the current vector command. The motor parameters vary because of magnetic saturation and as a result, the control performances are affected by the magnetic saturation. In this paper, the effects of magnetic saturation are examined and the control system considering the magnetic saturation is proposed. The performances of the proposed control system are examined by simulations and the experimental results with respect to the prototype interior permanent magnet synchronous motor

Harmonics: the effects on power quality and transformers

Abstract: The use of nonlinear devices such as rectifiers or converters, power supplies and other devices utilizing solid-state switching has increased in industry during. Unfortunately, the effect of harmonic distortion has also increased on the industrial power system as a direct result. This paper is based upon actual harmonic studies on 480 V, three-phase, variable speed drives and the effects of harmonics on transformers in those systems. It also includes the recommendations for correction of the problems resulting from harmonic distortion. >

Basic consideration of vibration suppression and disturbance rejection control of multi-inertia system using SFLAC (state feedback and load acceleration control)

Abstract: SFLAC (state feedback and load acceleration control) is proposed for vibration suppression and disturbance rejection control of a multi-inertia system A multi-inertia system is the model of a steel rolling mill, a flexible arm, a large-scale space structure, etc, and its control will be an important problem in the future of motion control The main idea of SFLAC is to control the load acceleration which can be estimated by the state observer including the disturbance estimation A simple PI speed controller and SFLAC based on the reduction models using two and three inertia moments are designed The effectiveness of SFLAC is demonstrated showing some simulation results >

Inverter nonlinearities and discrete-time vector current control

Abstract: This paper studies all-digital discrete-time vector current control loops containing a voltage fed invertor in series with a permanent-magnet synchronous motor. Normal operation of the typical pulse width modulating voltage fed inverter introduces nonlinear distortion into the voltage and the current waveforms of the motor. This paper focuses on both the causes and the attenuation of these disturbances using all-digital control. An effective, fully-digital current controller is developed and experimental results from a Motorola 68020 microprocessor based system are presented. >

A novel polyphase multipole square-wave permanent magnet motor drive for electric vehicles

Abstract: A novel high-power-density permanent magnet (PM) motor drive for electric vehicles (EVs) is proposed. The motor is a polyphase multipole square-wave PM motor, which can be classified as a kind of PM brushless DC motor. The distinct features of the proposed motor as compared to those of the conventional PM brushless DC motor are as follows. First, the multipole magnetic circuit arrangement enables the minimization of the magnetic yoke, resulting in the reduction of motor volume and weight. Second, the coil span is purposely designed to be equal to one slot pitch, thus saving the amount of copper used. Third, by using a fractional number of slots per pole per phase, the arrangement of the numbers of poles and slots is so unique that the magnetic force between the stator and the rotor at any rotating position is uniform, hence eliminating the cogging torque that usually occurs in PM motors. Finally, the motor can be controlled to operate at a constant torque region and a constant power region with field weakening, thus both high starting torque and high cruising speed can be achieved. Therefore, as the proposed motor drive possesses the distinct advantages of high power density, high efficiency, and superior dynamic performance, it is very suitable for EV applications. A prototype of a five-phase 22-pole 5 kW motor drive has been designed for an experimental EV. >

NO/sub x/ removal by a pipe with nozzle-plate electrode corona discharge system

Abstract: The effects of additional gas composition on the corona discharge characteristics in a pipe with nozzle electrode system and the NOx removal characteristics for flue gases are experimentally investigated. The additional gas consists of a mixture of Na+O/sub 2/+NH/sub 3/ and a small amount of Ar or CO/sub 2/, and is introduced to the flue gas stream from the pipe electrode through the corona discharging zone at the tip of nozzles. The results show that corona discharge characteristics and modes are significantly influenced by the composition of the additional gas mixture. Both NO/sub x/ reduction rate and energy yield of NO/sub x/ removal increase with decreasing corona discharge input power. NO reduction rate and energy yield can be optimized by the type of the additional gas mixture and the flow rates. >

On the design of high-performance surface-mounted PM motors

Abstract: This paper considers the major design factors which constrain the maximum acceleration capability of surface-mounted neodymium-iron-boron permanent magnet motors as used in servo drives. Expressions are derived for typical achievable values of the air-gap flux density and the linear current density around the stator periphery. For applications with small values of the duty factor, the stator linear current density is limited by the need to avoid demagnetization. For larger values of duty factor, the constraint is the ability of the cooling system to remove the heat losses within the magnet and insulation temperature limits. The paper derives general approximate expressions for maximum torque and acceleration limits, and shows graphs from which the range of acceleration capability of a permanent magnet motor in a given application can be assessed. The constraints involved in matching the motor design to an inverter with given maximum voltage capability are also discussed. >

Input Filter Design for PWM Current-Source Rectifiers

Abstract: Pulse-width modulated (PWM) rectifiers are increasingly used because they allow the elimination of low-order harmonics, and therefore a reduction in input filter components. Filtering requirements for PWM current-source rectifiers are usually satisfied through the use of low-pass LC input filters. This paper offers a systematic and user-friendly approach to choosing the filter components. Design of LC filters involves the positioning of the resonant frequency to meet the harmonic attenuation requirements (THD), and introducing damping at the resonant frequency to avoid amplification of residual harmonics. The problem is further complicated by considerations related to cost, power factor, voltage attenuation, system efficiency, and filter parameter variation. The systematic approach proposed in this paper focuses on PWM rectifiers, but can easily be extended to other classes of converters. Practical design considerations are detailed and design equations derived. Simulated results are presented to validate the design approach

Analysis and compensation of speed drive systems with torsional loads

Abstract: This paper proposes a fast and robust speed controller for motor drive systems having torsional loads and containing a gear backlash. The controller is designed using the state feedback technique combined with state variable observers and is implemented on a digital signal processor. Analysis, simulation and experimental results of a prototype speed drive system are presented and discussed. It is shown that the proposed speed controller yields a robust system with respect to system uncertainties and modeling errors and is very effective for the suppression of mechanical vibrations. >

An efficient switched-reactor-based static VAr compensator

Abstract: A new static VAr compensator is presented in this paper. To overcome the problems of large low-order harmonics and slow response associated with conventional thyristor-controlled-reactor based compensators, a pulse-width-modulated (PWM) AC converter is used to control the reactances of switched reactors. Yet unlike the PWM static VAr compensators previously reported in the literature, the proposed compensator has a simpler structure and its gating signals are easier to implement. Moreover, it does not require synchronization with the AC mains. The proposed concept was verified through a 1 kVAr prototype and the measured experimental results prove that either leading or lagging reactive power can be achieved through simply duty cycle control. >

An overview of fault monitoring and diagnosis in mining equipment

Abstract: Proper detection and diagnosis of failing system components is crucial to efficient mining operations. However, the harsh mining environment offers special challenges to these types of actions. The atmosphere is damp, dirty, and potentially explosive, and equipment is located in confined areas far from shop facilities. These conditions, coupled with the increasing cost of downtime and complexity of mining equipment, have forced researchers and operators to investigate alternatives for improving equipment maintainability. This paper surveys monitoring and diagnosis technologies that offer opportunities for improving equipment availability in mining. Expert systems, model-based approaches, and neural nets are each discussed in the context of fault detection and diagnosis. The paper concludes with a comparative discussion summarizing the advantages and disadvantages of each. >

Natural lightning

Abstract: The present understanding of natural lightning is reviewed. Research on lightning has been motivated, in part, by the need to protect advanced ground-based and airborne systems that utilize low voltage, solid-state electronics; by the desire to prevent spectacular accidents, such as occurred in 1969 during the launch of Apollo 12 and in 1987 during the launch of Atlas-Centaur 67; and by the desire to elucidate the physics of one of nature's most impressive phenomena. The author discusses lightning sources, natural lightning, negative and positive cloud-to-ground lightning, upward lightning, cloud discharges, top-of-the cloud and clear air lightning, lightning avoidance and lightning protection. >

A novel high-torque reluctance motor with rare-earth magnet

Abstract: An entirely new concept of an electromagnetic structure which exploits the excellent characteristics of a rare-earth magnet is proposed. Thin rare-earth metal magnet pieces are mounted on the surface of the stator teeth which face the airgap. The rotor has a variable reluctance structure type. This type of motor is suitable for low-speed high-torque applications by the action of tooth and slot structure. The relationship between the performance and electromagnetic geometry is investigated through the finite element method (FEM) analysis and experiments. The principle of torque generation and the associated characteristics is also introduced. >

Motion trajectory study in the scooping operation of an LHD-loader

Abstract: Mining operations have great potential for automation, from a worker safety viewpoint as well as productivity and efficiency. Among the operations that can be automated are loading, guiding, and unloading of LHD loaders. This paper concerns automatic loading of these units, based on modeling a loader as a robot manipulator. For this purpose, analysis of the forces concerned in the process of scooping, and information about the kinematics of motion become essential. This work is about the trajectory of motion during scooping. Based an the results of a preliminary study on the nature of the forces involved, and bearing in mind the preference for simplicity in the control action, an easy to follow trajectory is determined for the cutting edge of the bucket of a loader, which is regarded as the end-effector in a robot manipulator. The way to find a minimum energy consuming trajectory for each individual bucket and for a particular material to be loaded is discussed. Since following this trajectory is more efficient it can be used for faster execution of bucket loading, if desired. >

Control of a polyphase induction generator/induction motor power conversion system completely isolated from the utility

Abstract: Two squirrel cage induction machines interconnected via a 20 kHz parallel resonant high frequency (HF) AC link and associated switching pulse density modulated (PDM) power converters are investigated, one operating as a generator and the other as a motor. No capacitors are used for the excitation of the generator or motor. Instead, the real power of the generator is controlled so as to maintain the proper link voltage and match the power between the input and output, Current regulated PDM converters operating via field oriented controllers are used to control both machines. A zero voltage switching technique is utilized with the associated PDM converters. Low harmonic distortion waveforms have been obtained both at the input and output due to the high 40 kHz switching frequency. Link voltage build-up and excitation of the generator by an initial charging circuit, power matching between input and output, and peak link voltage regulation techniques are investigated. Both computer simulations and experimental results demonstrate the feasibility of the proposed system. >

The energy consumption of desktop computers: measurement and savings potential

Abstract: The energy consumption of desktop personal computers was studied at three Canadian Federal Government sites, and the potential for energy savings through power management investigated. The power draw of computers and their peripherals was measured using a portable meter, and use profiles were recorded using custom software. The measured plug loads were considerably lower than nameplate ratings. Use profiles from 94 computers indicated that there were long periods during both night and day when the computers were turned on but not being used, and it was predicted that significant energy savings could be achieved if electricity consumption was more closely tailored to actual usage. Two methods of realizing these savings were tested in the field. Stickers reminding users to switch off computers when they were not being used produced reductions in mean computer energy consumption of 14% over an eight week period. However, these savings diminished with time. An automatic power management system designed to switch off computers and peripherals after a user-specified period of inactivity produced reductions in mean computer energy consumption of 63%, while visual display unit mean energy consumption was reduced by 82%. These savings were maintained over an eight week period. >

A load commutated inverter-fed induction motor drive system using a novel DC-side commutation circuit

Abstract: A load-commutated current source inverter (LCCSI) induction motor drive system employing a novel DC-side forced commutation circuit for machine start-up is proposed. To avoid the adverse effects of harmonic resonance between the output capacitor and the inductance of the induction motor, a solution is proposed using a special type of one-notch current PWM, fully utilizing the proposed commutation circuit. A direct vector controller, which refers to the fixed reference frame of the rotor flux without using a speed sensor, is applied. In addition to compensating for the capacitive current, this controller is applied to decouple the torque and flux generating currents and to overcome the instability caused by the output capacitor. The feasibility of the proposed circuit for the high power drive system is verified by computer simulation for a 600 hp induction motor. Experimental results for a laboratory LCCSI-induction motor (10 hp) are also included. >

A novel position sensorless control scheme for doubly fed reluctance motor drives

Abstract: A novel position sensorless control algorithm for the newly developed doubly fed reluctance motor (DFRM) drives is presented. The control makes use of the 60 Hz terminal variables, which are easy to acquire and process, for estimation and control of the torque angle of the machine, while the speed of the system is given in an open-loop mode. The control is robust and suitable for variable-speed pump-type application. With this control, the required VA ratings of the PWM converter are only 50% of that of the DFRM motor, and the motor can be started with full load torque. This control scheme has been successfully implemented on a 2-HP DFRM drive. >

Advanced application of statistical and fuzzy control to textile processes

Abstract: A new control strategy is proposed to optimize the slasher control parameters and the slashing operation during normal, transient and creep speed. An expert system detects and identifies off-limits or failure conditions and generates command signals for low level control of slasher components such as creel, size box drying section and beamer drive. It also addresses the issues of system integration between warping and weaving at a hierarchical level. Simple process models for each section of a slasher are simulated on computers. Simulated results from these models demonstrate that the control strategy is efficient and robust. >

Modern technology impact on power usage in cement plants

Abstract: As a trend, both power usage and power rates have increased such that in many North American and European cement plants, the cost of electricity is now higher than the cost of fuel. This is expected to worsen. As a result, many new technological innovations have begun to appear which will enable cement producers to combat this alarming trend. The purpose of this paper is to provide an overview of these advances-some are well known, others are leading edge. All of them feature ways to reduce specific power usage in the cement industry. By increasing awareness, producers will be able to better formulate their own plans in their ongoing battle to control costs. The technologies discussed cover electrical power management, gas handling and pneumatic systems, motors and transformers, and comminution and separation. >

Minimization of acoustic noise in variable speed induction motors using a modified PWM drive

Abstract: This paper describes an effective way of reducing acoustic noise in a motor supplied from an adjustable speed PWM drive. The PWM patterns are selected to eliminate the most acoustically sensitive harmonics in the motor's vibration spectra. This permits the PWM drive to use more economical yet slower switching devices while maintaining quiet operation. This method is applicable to both voltage source and current source inverters since the current waveform is used as the basis for eliminating the objectionable harmonics. >

Thick film heater elements and temperature sensors in modern domestic appliances

Abstract: This paper describes the use of thick film heating elements in domestic appliances, and comparison is made of performance and cost between thick film and traditional heaters. Thick films are created by screen printing pastes, usually containing glass and metal powders, onto a flat substrate. A brief explanation of thick film technology is given. This technology has been used for many years in the electronics industry to produce circuits containing conductors, resistors and dielectrics. The structure of a thick film resistor makes it ideal for heating applications, and it may be deposited on a number of substrate materials. Experimental data demonstrating that thick films make effective and reliable heating elements and temperature sensors are presented. The combination of a thick film heating element with thick film temperature sensor on an insulated steel substrate is described. >

Implementation of discrete-time field-oriented current control

Abstract: This paper studies performance sensitive issues encountered in the implementation of all-digital discrete-time field oriented current control of an AC motor. In particular, the focus here is on the interface between the vector current control algorithm itself, and the motor/inverter system. The effects of interface components such as antialiasing filters, rotational transformations, and phase-to-line-voltage transformations are analyzed. In addition, a straightforward all-digital pulse width modulator is presented along with a new algorithm to naturally inject triplen harmonics into the motor line voltages, and thereby increase power supply utilization by 15%. Real-time operation of a discrete-time vector current controller verifies the analysis. >

Modulation Strategies for a New SCR-Based Induction Motor Drive System with a Wide Speed Range

Abstract: A new SCR-based naturally commutated induction motor drive that provides high torque over a wide speed range is presented. Topology is similar to that of certain naturally commutated current source inverters, but modulation techniques and system performance are very different. Two novel switching algorithms are proposed to cover the low-speed and high-speed regimes. Torque ripple is negligible in the low-speed region. With these two switching techniques, commutation is reliable and operation within peak device voltage stress limits is guaranteed. For induction machine loads, this drive has the torque-speed capability typical of a cycloconverter (but with far fewer devices), plus a field weakening range that the cycloconverter does not have. Simulation and experimental results are presented

Digital control for brush DC motor

Abstract: In home appliances applications the brush DC motor, driven by a chopper, can be controlled by a standard microcontroller. However people often consider the microcontrollers as not suitable for the power environment because of their limited computing speed or noise immunity problems. This paper shows how a cost effective digital motor drive can be designed by combining a chopper and an 8 bits microcontroller: the speed is simply controlled through direct voltage compensation and motor power limitation. The microcontroller implements both motor control and interface functions of the application: it replaces the analog circuits of the conventional motor control. Performances and practical results are given for a 300 W/12000 RPM motor drive. >

A novel simulation technique for the analysis of digital asynchronous pulse width modulation

Abstract: A digital simulation technique based on single Fourier series is used to predict the spectra, including the nonintegral harmonics, generated by digital asynchronous pulse width modulation invertors. The results, with an accuracy of 70 dB, are superior to the results obtained with fast Fourier transform techniques, and offer an alternative to the complex methods based on double Fourier integration and Bessel functions. The technique is applicable to any choice of reference waveform. Output distortion with the introduction of minimum pulse and dead time is studied. >

An output feedback sliding mode speed regulator for DC drives

Abstract: Synthesis of the switching surface equation in a variable structure speed controller is accomplished by using a phase lead type compensator. In addition, the switching control is designed using only the sign of the switching surface function and an estimate of the maximum value of the equivalent sliding control. As a result, the proposed variable structure controller relies only upon output feedback. The problem of control chattering is addressed by substituting a saturation function for the switching control. The practical significance of the work is demonstrated by designing a robust speed regulator for a DC drive, without direct acceleration measurement or the use of a state estimator. Results from a control experiment complement the discussion. >

Sensor fusion for mining robots

Abstract: The use of robots for work in hazardous or unpleasant environments is one factor driving the demand for machines of ever-increasing autonomy and intelligence. Such machines are required to sense and interpret situations, plan strategies, and execute tasks with nearly absolute reliability. Negotiation of complex environments requires the use of a variety of different sensor types and the interpretation of conflicting or missing data, diagnosis of faulty sensors, and the ability to reconfigure a system to work with a partially inoperative sensor suite. This paper focuses on the issues of integration of information from disparate sensor types in the presence of noise and uncertainty. The application is a mobile robot called the autonomous navigation testbed being used at West Virginia University for research in mining robot applications. This paper describes both traditional control techniques and neural network-based methods being used to interpret data from a variety of sensors on the mobile testbed. >

Analysis of soft breakdown failure with ESD on output buffer nMOSFETs and its improvement

Abstract: The leakage increase of the off-state MOSFETs after an ESD event has been studied for output transistors with the thin gate oxide and LDD structures. Leakage increase called "soft breakdown" has been found at relatively low ESD testing voltages (200-300 V). This soft breakdown is caused by the creation of interface traps due to the snap-back stressing during the ESD event. The creation of interface traps has enhanced the interface trap to band tunneling current at the drain side of the MOSFETs. The improvement of the ESD threshold has also been proposed with an additional arsenic implantation into the n/sup $/region. It has been confirmed that the arsenic implantation improved the HBM ESD threshold to more than 2000 V. >