Showing papers in "IEEE Transactions on Industry Applications in 1981"
TL;DR: The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.
Abstract: A new neutral-point-clamped pulsewidth modulation (PWM) inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed. This inverter output contains less harmonic content as compared with that of a conventional type. Two inverters are compared analytically and experimentally. In addition, a new PWM technique suitable for an ac drive system is applied to this inverter. The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.
4,328 citations
TL;DR: In this article, the results of the research concerned with the problem of induction motor control system synthesis using variable structure systems theory are presented, as well as basic experimental results and problems related to realization of the proposed control algorithms.
Abstract: The results of the research concerned with the problem of induction motor control system synthesis using variable structure systems theory is presented. The procedure of control systems synthesis for the control of position speed and torque is given, as well as basic experimental results and problems related to realization of the proposed control algorithms.
235 citations
TL;DR: In this paper, the delta modulation (DM) technique fulfills the aforementioned performance requirements with a minimum of circuit complexity, smooth inverter operation and with improved system reliability, while making compromises in terms of control circuit complexity.
Abstract: Pulsewidth modulation (PWM) techniques are employed in voltage-source inverters to produce a variable output voltage containing the least possible harmonic distortion over a wide frequency range. To achieve these objectives, compromises are made in terms of control circuit complexity, smoothness of inverter operation, and overall system reliability. The delta modulation (DM) technique fulfills the aforementioned performance requirements with a minimum of circuit complexity, smooth inverter operation and with improved system reliability.
182 citations
TL;DR: In this article, the output filter inductance and the input filter capacitance for a single-phase uncontrolled bridge rectifier employed for low power de-to-dc converters or inverters is established.
Abstract: The ``optimum'' output filter inductance Lf and the input filter capacitor Ci for a single-phase uncontrolled bridge rectifier employed for low power de-to-dc converters or inverters is established. The filter Ci is optimized to obtain maximum input power factor, minimum filter inductance, and minimum output dc voltage regulation. A design example is provided and theoretical results have been verified on an experimental model.
100 citations
TL;DR: In this paper, a closed-form analytic current-voltage formula for duct electrostatic precipitators is presented, and a short discussion of previous theoretical and numerical solutions is given, followed by an explanation of the theoretical formula derived here.
Abstract: A closed-form analytic current-voltage formula for duct electrostatic precipitators is presented. A short discussion of previous theoretical and numerical solutions is given, followed by an explanation of the theoretical formula derived here. A comparison with experimental data is then given, showing that the present formula is accurate over a wide range of conditions, including wide plate spacing.
67 citations
TL;DR: In this article, the IEEE Standard 112, the recognized test procedure in the United States, has been revised and compared with IEC 34-2 and JEC-37, which includes a variety of basic methods for determining efficiency.
Abstract: Electric motor drives are significant to the overall energy requirements of the country and the world. The majority of these electric motors are squirrel cage induction motors, and it is to the efficiency testing of these motors that this paper is directed. It is essential that motor efficiencies be determined accurately to allow true comparisons to be made between alternate offerings and to assess correctly the motor's share of system energy consumption. IEEE Standard 112, the recognized test procedure in the United States, has recently been revised. This paper presents the revised methods and compares this Test Procedure with IEC 34-2 and JEC-37. Each of these specifications includes a variety of basic methods for determining efficiency based on motor size and availability of test equipment. The National Electrical Manufacturers' Association has recommended the use of IEEE Standard 112, Method B for ac motors of 1-125 hp. Ranking of different methods in order of desirability and practicality of use is presented.
62 citations
TL;DR: With the widespread application of these economical power supplies, problems are arising that should be approached from a logical standpoint and preventive measures taken.
Abstract: In the last 50 or 60 years, the development of rectifier and semiconductor technology has led to new products and applications for drives in all industries. These semiconductor converters produce harmonics in the ac power system. With the widespread application of these economical power supplies, problems are arising that should be approached from a logical standpoint and preventive measures taken. The theory of the problem and the solution to it is discussed.
54 citations
TL;DR: In this paper, a new type of air filter in which the dust particles are captured very effectively by electrostatic forces is presented, which is accomplished by making the filter from polymer fibers that carry a permanent positive and negative charge.
Abstract: A new type of air filter in which the dust particles are captured very effectively by electrostatic forces is presented. This is accomplished by making the filter from polymer fibers that carry a permanent positive and negative charge. A method is outlined for producing such filters on a large scale and results are given of tests in which the filters are challenged with various aerosols. The advantage of the new filters is that they combine a high capturing efficiency with a low resistance to air flow. Among the numerous applications, personal protective face masks for people working in dusty environments are especially valuable.
54 citations
TL;DR: In this article, the transient performance of self-controlled synchronous motors which are used as variable speed motors in industries is analyzed considering two types of position sensor used in these motors.
Abstract: The transient performance of self-controlled synchronous motors which are used as variable speed motors in industries is analyzed considering two types of position sensor used in these motors. A set of equations valid for the transient state is first derived and represented in a block diagram. Based on these equations, mechanical and electrical transient responses of the motors in the case of a step change in input voltage are analyzed. It is shown that the transient responses differ remarkably depending on the type of position sensor used. The transient characteristics of margin angle of commutation of thyristors are then compared in detail with the steady-state ones. It is shown that the thyristors in the inverter are commutated more successfully in the transient state than in the steady state when compared at the same dc input current. Finally, the transient responses in the case of a step change in load torque are investigated.
47 citations
TL;DR: In this article, a general understanding of the fundamental nature and cause of various types of torsional problems provides the basis for defining and conducting design assurance analyses, which can greatly reduce the risk of developing problems.
Abstract: Torsional vibrations in various types of drives utilized by the cement industry can have a large economic impact due to lost production when consequential component failures result in unscheduled shutdowns. Each type of drive will have a different set of torsional vibration problems that can develop under certain conditions. A general understanding of the fundamental nature and cause of various types of torsional problems provides the basis for defining and conducting design assurance analyses. Such analyses can greatly reduce the risk of developing problems. A discussion aimed at such an understanding, along with examples of problem experiences and analyses carried out on industry drives, is given.
47 citations
TL;DR: In this paper, a nonlinear dynamic model of the terminal voltagecurrent (V-I) characteristics of a mercury arc lamp operating at various power levels is described and an experimental and efficient computational procedure is developed which determines the values for six model constants that cause the model to duplicate actual lamp behavior.
Abstract: A nonlinear dynamic model of the terminal voltagecurrent (V-I) characteristics of a mercury arc lamp operating at various power levels which can be used in the computer design of lamp ballast circuits is described. An experimental and efficient computational procedure is developed which determines the values for six model constants that cause the model to duplicate actual lamp behavior. This model is shown to be accurate within five percent in simulating lamp voltage and current waveforms when operated at frequencies from dc to 30 kHz. An example of a computer design of a high frequency ballast circuit is presented using the lamp model as the dynamic load in the ballast circuit.
TL;DR: In this article, a simplified second-order model for induction machines is presented, which reduces the computational requirements previously considered necessary to predict electrical rotor transients, as well as mechanical transients.
Abstract: Several simplified models of induction machines are presented. Included is a novel second-order model, which reduces the computational requirements previously considered necessary to predict electrical rotor transients, as well as mechanical transients. It is shown that the reduced-order models can be readily adapted to unbalanced voltage inputs without raising model order, thus providing increased flexibility. The model responses are compared for symmetrical voltage dips, start-up, and a sudden single-phasing condition.
TL;DR: In this article, the problem of simulating the transient performance of three-phase induction motors is discussed and a method of solution by digital simulation using phase variables has been developed and is presented.
Abstract: The problem of simulating the transient performance of thyristor controlled three-phase induction motors is discussed. A method of solution by digital simulation using phase variables has been developed and is presented. The method enables transient current, speed, and electromagnetic torque patterns to be predicted for run-up conditions and conditions of operating mode transition. Application of the method is illustrated and sample results are presented and discussed.
TL;DR: In this paper, a steady-state analysis of a PM synchronous motor drive with a voltage-source inverter (VSI) is presented, where the harmonic distortion in the motor is strongly dependent on the presence and configuration of dampers.
Abstract: A steady-state analysis of a permanent magnet (PM) synchronous motor drive with a voltage-source inverter (VSI) is presented. The torque-speed profile required of the drive is a constant torque region from zero to base speed and a constant power region above base speed. Assuming position feedback control from a shaft-position sensor, optimum strategies are obtained for the two regions of the torque-speed profile. Using these optimum strategies, performance curves of the drive are predicted and experimentally verified. The harmonic distortion in the motor is strongly dependent on the presence and configuration of dampers in the motor. An expression is obtained for the equivalent inductance seen by the harmonics for different damper configurations. A Fourier series approach is used to predict the line current waveforms. Since dampers are not otherwise essential to the operation of this type of drive and since the line current without dampers is nearly sinusoidal, it is concluded that it is advantageous not to have dampers in the motor.
TL;DR: In this article, a load-flow and short-circuit analysis of a coal mine power system is presented, where the topology of the dc network is constantly changing due to the movement of locomotives along the track.
Abstract: Many present-day industrial power systems have combined ac/dc power distribution systems. A typical example is a coal mine power system, where ac is used for running the mining equipment and dc is used for track haulage, etc. Also, the topology of the dc network is constantly changing due to the movement of locomotives along the track. Methods are described that can be used to carry out load-flow and short-circuit analyses of such a system.
TL;DR: In this paper, a linear synchronous motor (LSM) drive cycloconverter was used for super-high-speed running tests on Miyazaki test track, where the current can be arbitrarily controlled in a range of 200-1300 A. Despite the rigorous power conversion and control, excellent current control characteristics were obtained.
Abstract: Maglev vehicle ML-500 in Japan attained a speed of 517 km/h on December 21, 1979. The linear synchronous motor (LSM) drive cycloconverter fabricated and submitted to the track test has a capacity of approximately 12 000 kVA in a continuously variable frequency range of 0-34 Hz with a sinusoidal current waveform. The current can be arbitrarily controlled in a range of 200-1300 A. Despite the rigorous power conversion and control, excellent current control characteristics were obtained: less than 4 percent in deviation of current peak value, about 4 ° in leading phase deviation and approximately 1.2 ms in zero current interval. Some observations about the LSM driving system are made, and an outline of the design and the data obtained from the super-high-speed running tests on Miyazaki test track are given.
TL;DR: In this article, the precipitator duct spacing is increased from the traditional 200-300 mm up to 400-600 mm, and the voltage is raised correspondingly, with precipitators performance remaining almost unchanged for the same volume and the same gas flow.
Abstract: Increased research in electrostatic precipitation has resulted in the emergence of promising new technologies. In a new design concept already widely used in Japan, the precipitator duct spacing is increased from the traditional 200-300 mm up to 400-600 mm, and the precipitator voltage is raised correspondingly, with precipitator performance remaining almost unchanged for the same precipitator volume and the same gas flow. For suitable applications, this design results in reduced installation costs and easier maintenance. Various devices for precharging of high resistivity dust now under development improve particle charging and thereby enhance precipitator performance. Pulse energization improves the performance of precipitators collecting high resistivity dust by improving particle charging and current distribution and allowing regulation of the precipitator current independent of precipitator voltage.
TL;DR: In this article, a six-step and twelve-step current-source inverter with dc side commutation and energy rebound capability is presented with detailed explanation of the circuit operation.
Abstract: Novel six-step and twelve-step current-source inverters (CSI) with dc side commutation and energy rebound capability are presented with detailed explanation of the circuit operation. The proposed inverters can operate in a very wide range of frequency and load variation by employing dc side commutation. Also, the energy rebound makes the use of low voltage silicon controlled rectifiers (SCR's) possible and increases the inverter efficiency. Unlike the dual current-source inverter, one auxiliary inverter with a power requirement of about one-half that of the main inverter is simply added to the six-step CSI in order to obtain a twelve-step CSI. Motor operation is possible in four quadrants in both six-and twelve-step inverters. The advantages of the proposed CSI's over conventional ones are described, and experimental results are given in oscillograms.
TL;DR: In this paper, the problem of reducing the pulsating torque in current source inverter induction motor systems is investigated, and two typical approaches presented in recent publications are analyzed by making clear the correlation among the current harmonics and the torque harmonics, and the conceptual contradiction existing between these two approaches.
Abstract: The problem of reducing the pulsating torque in current source inverter induction motor systems is investigated. Two typical approaches presented in recent publications are analyzed by making clear 1) the correlation among the current harmonics and the torque harmonics, and 2) the conceptual contradiction existing between these two approaches. By synthesizing the analyzed results, fundamental principles for treating the current harmonics and torque harmonics are established. In addition, the method for evaluating the degree of torque ripple is described, along with a proposed criterion for torque ripple content. By applying this criterion to these two approaches, objective estimates of degree of torque pulsations, which were unfeasible so far, are now made possible.
TL;DR: In this article, a relatively straight forward analytical method of calculating the motor-developed air-gap torque from the d and q axis equivalent circuits is presented, and a method of assessing the capability of a shaft section to withstand a given torsional duty is also presented.
Abstract: The increasingly frequent use of larger four-pole and six-pole synchronous motors to drive high speed equipment, such as compressors, has focused much attention on coordination of the motor and driven equipment system. A relatively straight forward analytical method of calculating the motor-developed air-gap torque from the d and q axis equivalent circuits is presented. The problem of relating air-gap torque to shaft torque is discussed briefly, and methods of experimentally determining both quantities are presented. A method of assessing the capability of a shaft section to withstand a given torsional duty is also presented.
TL;DR: New applications of electrostatics to the control of dust are investigated in this paper, where pushing systems to keep dust off optical systems and move particulates out of airstreams are discussed.
Abstract: New applications of electrostatics to the control of dust are investigated Technology for pushing systems to keep dust off optical systems and move particulates out of airstreams are discussed Other electrostatic techniques for removal of water droplets and smoke are investigated
TL;DR: In this article, the authors considered possible spectral errors resulting from the application of theoretically optimized pulsewidth modulated (PWM) waveforms to physical power converters, produced by commutation rise and fall times, timing errors, and amplitude ripple, and analyzed in terms of switching, ramp and ripple functions.
Abstract: Possible spectral errors resulting from the application of theoretically optimized pulsewidth modulated (PWM) waveforms to physical power converters are considered. These errors, produced by commutation rise and fall times, timing errors, and amplitude ripple, are synthesized and analyzed in terms of switching, ramp, and ripple functions. Probabilistic and heuristic results show the relative sensitivity of the error producing terms independent of the PWM technique.
TL;DR: In this article, the authors discuss the importance of neutral grounding and ground fault protection for in-plant generators, which are normally connected to the main plant distribution bus, and the effects of internal ground faults.
Abstract: Increasing ``energy consciousness'' in industry is causing expanded interest in in-plant generators, which are normally connected to the main plant distribution bus. Electrical system reliability requires the proper application of neutral grounding and ground fault protection for these machines. Mechanical limits on safe generator ground fault currents, possible circulating harmonic currents in multiunit installations, and the effects of internal ground faults add complexity.
TL;DR: In this paper, the effect of the field shaping short-circuited turn (screen) on the field strength, pressure and force factors was examined using a one-dimensional field model and a two-dimensional semi-infinite model.
Abstract: Electromagnetic molds are presently being used in the continuous casting of aluminum billets and slabs. Various theoretical models that can be used to predict electromagnetic pressure differentials and forces for this application are examined. Dimensionless pressure and force factors are first derived using a one-dimensional field model. These factors are then refined using a two-dimensional semi-infinite model. This latter model is also used to examine the effect that coil coupling has on the field strength, pressures and forces. Finally, the coupled circuit method is used to predict pressure distributions for an actual mold geometry, including the essential effect of the field shaping short-circuited turn (screen). The effect of varying the location of the inductor and screen is examined.
TL;DR: A control system is described in which a current-source inverter is connected between the secondary winding of a three-phase slip-ring induction motor and the ac mains supply to give a variable speed sub- and supersynchronous operation.
Abstract: A control system is described in which a current-source inverter is connected between the secondary winding of a three-phase slip-ring induction motor and the ac mains supply to give a variable speed sub- and supersynchronous operation. Control techniques developed in an earlier work were used to ensure fully stable operation over a very wide speed range with either driving or braking torque. Means are provided for power-factor control to compensate for the lagging power-factor effect of the inverter when operating into the large secondary electromotive forces (EMF) at high slip values. Experimental results are presented for a speed range from standstill to approaching twice synchronous speed for both driving and braking torque. There are no instabilities and the developed torque even at low frequencies near synchronous speed is steady with motor derating due only to the quasi-square wave current in the secondary circuit.
TL;DR: The NEMA Standard on Motor Efficiency (SME) as discussed by the authors has been used by motor manufacturers and users for several years and several years of work has been invested in preparing and validating the standard.
Abstract: With the continuing escalation of the cost of electrical energy, motor manufacturers and appliers are increasingly concerned with the energy conservation available from high efficiency electrical motors. The revised NEMA Standard on Motor Efficiency is described, as well as its use by motor manufacturers and users and the several years of work invested in preparing and validating the standard.
TL;DR: An electric drive suitable for traction is described consisting of a cycloconverter and a synchronous motor, which can be used with either single-phase or three-phase input with frequencies around 50-100 Hz.
Abstract: An electric drive suitable for traction is described consisting of a cycloconverter and a synchronous motor. Essentially, the same system can be used with either single-phase or three-phase input with frequencies around 50-100 Hz. The motor speed range is not limited by the input frequency. The cycloconverter thyristors are commutated by the source voltage at low motor speed and by the motor electromotive force (EMF) at higher speed. The transition between the two regions is smooth and automatic. Only 16 low- switching speed thyristors are required for the single-phase input system. The short time overload capability of this drive at low speed is excellent, and full range regenerative, as well as dynamic braking, is readily accomplished. Compared to dc motors occupying the same space, three-phase ac motors, both synchronous and induction, offer higher output power, higher efficiency, and the elimination of brush and commutator maintenance. Compared to inverters, cycloconverters have higher efficiency and lower cost and weight.
TL;DR: A microprocessor-based control system is described for an electric vehicle where the microprocessor has the responsibility of propulsion feedback control, drive system sequencing control, battery ``fuel gauging,'' battery charging/equalization control, and some amount of diagnostics.
Abstract: A microprocessor-based control system is described for an electric vehicle where the microprocessor has the responsibility of propulsion feedback control, drive system sequencing control, battery ``fuel gauging,'' battery charging/equalization control, and some amount of diagnostics. The system functions were analyzed and implemented in Intel-8080-based hardware and software. The control system was tested systematically in the laboratory and in the field and shows excellent performance.
TL;DR: In this article, the authors presented a formula to calculate the optimum interval for preventive maintenance and diagnostic testing of electrical equipment, where each user can calculate his own custom intervals using the formulas which are based on least total annual costs.
Abstract: Formulas to calculate the optimum interval of preventive maintenance and the optimum interval of diagnostic testing of electrical equipment are presented. Each user can calculate his own custom intervals using the formulas which are based on least total annual costs. The user must have his own data base of equipment failures similar to the example presented. Using 10000 failures of electric utility control and monitoring equipment as a sample, it was found that 25 percent of the failures could have been prevented by preventive maintenance, 65 percent could have been caught by diagnostic testing, and less than 10 percent have failed in the operative mode and could not have been maintained against or caught beforehand. One factor in the formula, which determines the shape of the equipment failure curve, remains to be proven after the next five years of data are collected.
TL;DR: The experimental machine combines the torque characteristics of a conventional cage induction machine with the leading power-factor capability of an overexcited dc field synchronous condenser into one unit using a common cage rotor and a common stator core.
Abstract: Several designs detailing the construction of brushless cage-rotor induction machines operating at unity or leading power factor at the 35-hp level have recently been published [1]-[3]. The experimental machine combines the torque characteristics of a conventional cage induction machine with the leading power-factor (PF) capability of an overexcited dc field synchronous condenser into one unit using a common cage rotor and a common stator core. The ability of this machine to naturally commutate a high-power current-source thyristor inverter is apparent without any need for capacitors. The preferred adjustable speed propulsion arrangement consists of a mains-fed phase-delay-rectifier (PDR), high-voltage dc link, and a current-source inverter powering a ten-pole traction motor with constant V/Hz control. The drive system provides continuously variable torque during motoring, and regenerative braking modes and specific details are given for a 150-hp cage-rotor traction motor and converter, capable of natural commutation up to 200 Hz, currently under development.