The method presented uses finite-difference and current-conservation equations, but applies them on a grid which is continuously adjusted by relaxation to approximate flux tube and equipotential surfaces. The resulting solution then contains the flux lines and equipotential lines explicitly. The primary advantages for using the method are that numerical diffusion of the ions is avoided, and the method is adaptable able to include physical diffusion terms.<>
{"title":"Numerical solutions of Laplace's equations and the ion current problem by the use of flux tubes and equipotentials (FTE)","authors":"P. Lawless","doi":"10.1109/IAS.1988.25286","DOIUrl":"https://doi.org/10.1109/IAS.1988.25286","url":null,"abstract":"The method presented uses finite-difference and current-conservation equations, but applies them on a grid which is continuously adjusted by relaxation to approximate flux tube and equipotential surfaces. The resulting solution then contains the flux lines and equipotential lines explicitly. The primary advantages for using the method are that numerical diffusion of the ions is avoided, and the method is adaptable able to include physical diffusion terms.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124798083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A description is given of the design and implementation of a simple scheme to achieve online and dynamic power-factor improvement of single and three-phase induction motors subjected to variable loads. The proposed scheme uses a fixed-capacitor thyristor-controlled-reactor type of static compensator along with associated control circuits. The results show that under all loading conditions, a power factor of almost unity is achieved automatically. The waveform of supply current can be kept almost sinusoidal. The response time of the scheme to motor load changes is quite reasonable. Details regarding design, implementation, analysis and operation of such dynamic power-factor compensators are provides.<>
{"title":"Online power factor improvement of induction motors","authors":"S. Haque, N. Malik, M. Smiai","doi":"10.1109/IAS.1988.25257","DOIUrl":"https://doi.org/10.1109/IAS.1988.25257","url":null,"abstract":"A description is given of the design and implementation of a simple scheme to achieve online and dynamic power-factor improvement of single and three-phase induction motors subjected to variable loads. The proposed scheme uses a fixed-capacitor thyristor-controlled-reactor type of static compensator along with associated control circuits. The results show that under all loading conditions, a power factor of almost unity is achieved automatically. The waveform of supply current can be kept almost sinusoidal. The response time of the scheme to motor load changes is quite reasonable. Details regarding design, implementation, analysis and operation of such dynamic power-factor compensators are provides.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124980704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Memory state switching is applied to a transient-mode inverter exciting three pairs of Helmholtz coils. The inverter, deploying four transistors and three TRIACS, generates nonrepetitive, orthogonal magnetic fields. Power semiconductor states are predetermined through analysis, digitized, and programmed into an EPROM (erasable programmable read-only memory). The EPROM is then cycled to produce the desired results. The system is intended for demagnetizing ferromagnetic materials in random orientation. Results are presented for an inverter producing a magnetizing force of 350 Oe.<>
{"title":"Demagnetizing inverter using memory state switching techniques","authors":"I. Pitel","doi":"10.1109/IAS.1988.25174","DOIUrl":"https://doi.org/10.1109/IAS.1988.25174","url":null,"abstract":"Memory state switching is applied to a transient-mode inverter exciting three pairs of Helmholtz coils. The inverter, deploying four transistors and three TRIACS, generates nonrepetitive, orthogonal magnetic fields. Power semiconductor states are predetermined through analysis, digitized, and programmed into an EPROM (erasable programmable read-only memory). The EPROM is then cycled to produce the desired results. The system is intended for demagnetizing ferromagnetic materials in random orientation. Results are presented for an inverter producing a magnetizing force of 350 Oe.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130268129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Rogne, N.A. Ringheim, B. Odegard, J. Eskedal, T. Undeland
The IGBT (insulated-gate bipolar transistor) or COMFET (conductivity-modulated field-effect transistor) has the same low drive requirements as for MOSFETs and the same carrier injection as a bipolar transistor, giving a low voltage drop even at high breakdown voltage ratings. The authors study the short-circuit capability. The high-current level or active region is found for different IGBTs. The short-circuit endurance time is investigated. The measurements show clear differences between the IGBTs from different manufacturers. The gate voltage is shown to be an important parameter.<>
{"title":"Short-circuit capability of IGBT (COMFET) transistors","authors":"T. Rogne, N.A. Ringheim, B. Odegard, J. Eskedal, T. Undeland","doi":"10.1109/IAS.1988.25125","DOIUrl":"https://doi.org/10.1109/IAS.1988.25125","url":null,"abstract":"The IGBT (insulated-gate bipolar transistor) or COMFET (conductivity-modulated field-effect transistor) has the same low drive requirements as for MOSFETs and the same carrier injection as a bipolar transistor, giving a low voltage drop even at high breakdown voltage ratings. The authors study the short-circuit capability. The high-current level or active region is found for different IGBTs. The short-circuit endurance time is investigated. The measurements show clear differences between the IGBTs from different manufacturers. The gate voltage is shown to be an important parameter.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127824022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The author presents typical electrical circuits that can be used to interface a minewide monitoring system with coal-mine conveyor-belt control circuits. Some considerations and justifications for monitoring and for remotely controlling conveyors are presented. The basic conveyor control circuit in common use is presented and discussed.<>
{"title":"Considerations for remotely monitoring and controlling conveyor belts in underground coal mines","authors":"R. Munz","doi":"10.1109/IAS.1988.25219","DOIUrl":"https://doi.org/10.1109/IAS.1988.25219","url":null,"abstract":"The author presents typical electrical circuits that can be used to interface a minewide monitoring system with coal-mine conveyor-belt control circuits. Some considerations and justifications for monitoring and for remotely controlling conveyors are presented. The basic conveyor control circuit in common use is presented and discussed.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"155 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127574226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two analytic solutions for the optimal switching vector for a third-order system are obtained. The tedious computation associated with the conventional trial and error selection of the weighting matrix and numerical solution of the Riccati equation in optimal control problems can be avoided. The novel design technique is shown to have identical results to that based on the minimization of the quadratic performance index with a suitable weighting matrix. Substantial improvement in performance over that reported in the literature is achieved. The performance obtained is insensitive to variations in system parameters and load disturbance.<>
{"title":"Synthesis of optimal sliding mode control for robust DC drive","authors":"J. Zhang, W. Chan, A. Wang, T. H. Barton","doi":"10.1109/IAS.1988.25112","DOIUrl":"https://doi.org/10.1109/IAS.1988.25112","url":null,"abstract":"Two analytic solutions for the optimal switching vector for a third-order system are obtained. The tedious computation associated with the conventional trial and error selection of the weighting matrix and numerical solution of the Riccati equation in optimal control problems can be avoided. The novel design technique is shown to have identical results to that based on the minimization of the quadratic performance index with a suitable weighting matrix. Substantial improvement in performance over that reported in the literature is achieved. The performance obtained is insensitive to variations in system parameters and load disturbance.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"123 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120863191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Near-sinusoidal-waveform currents of unity power factor can be obtained from the sinusoidal PWM (pulsewidth-modulated) rectifier using indirect current control. It is shown that the indirect current control must compensate dynamically for LdI/dt or else the stability region is very restricted. When correctly compensated, the dynamic indirect current controller can operate arrays of identical bridge rectifier modules in parallel and/or in series to augment the power ratings. By evenly staggering the phase shifts of the triangular carrier to each module in the arrays, switching harmonics can be eliminated. High-quality waveforms can be synthesized with slow switching devices such as GTOs (gate-turn-offs) and even force-commutated thyristors. Switching losses are also reduced.<>
{"title":"Dynamically stabilized indirect current controlled SPWM boost type 3-phase rectifier","authors":"J. Dixon, B. Ooi","doi":"10.1109/IAS.1988.25139","DOIUrl":"https://doi.org/10.1109/IAS.1988.25139","url":null,"abstract":"Near-sinusoidal-waveform currents of unity power factor can be obtained from the sinusoidal PWM (pulsewidth-modulated) rectifier using indirect current control. It is shown that the indirect current control must compensate dynamically for LdI/dt or else the stability region is very restricted. When correctly compensated, the dynamic indirect current controller can operate arrays of identical bridge rectifier modules in parallel and/or in series to augment the power ratings. By evenly staggering the phase shifts of the triangular carrier to each module in the arrays, switching harmonics can be eliminated. High-quality waveforms can be synthesized with slow switching devices such as GTOs (gate-turn-offs) and even force-commutated thyristors. Switching losses are also reduced.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"341 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123397813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-10-02DOI: 10.1080/07313569308909668
A. Boglietti, P. Ferraris, M. Lazzari, F. Profumo
The utilization of high-quality magnetic materials, such as amorphous, microcrystalline or cubic texture materials, for designing the magnetic structure of medium size induction motors has been investigated. To evaluate their benefits of reducing iron losses in AC motors, some computer computations have been carried out considering the characteristic of such materials (induction versus specific losses) and the results for different solutions have been compared. To verify the theoretical results the authors obtained a prototype 20 hp, 380 V, three phase induction motor using nonconventional magnetic material has been designed and built. The measurements carried out on the prototype to evaluate the iron losses confirm the computation results.<>
{"title":"Preliminary considerations about the adoption of unconventional magnetic materials and structures for induction motors","authors":"A. Boglietti, P. Ferraris, M. Lazzari, F. Profumo","doi":"10.1080/07313569308909668","DOIUrl":"https://doi.org/10.1080/07313569308909668","url":null,"abstract":"The utilization of high-quality magnetic materials, such as amorphous, microcrystalline or cubic texture materials, for designing the magnetic structure of medium size induction motors has been investigated. To evaluate their benefits of reducing iron losses in AC motors, some computer computations have been carried out considering the characteristic of such materials (induction versus specific losses) and the results for different solutions have been compared. To verify the theoretical results the authors obtained a prototype 20 hp, 380 V, three phase induction motor using nonconventional magnetic material has been designed and built. The measurements carried out on the prototype to evaluate the iron losses confirm the computation results.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123995121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The authors seek to quantify the influence of various common materials (copper, aluminium, brass, zinc, tin, lead and cold-rolled and stainless steels) on the probability of spark ignition in 8.3% methane-air. Results presented indicate the current necessary to produce a probability of spark ignition of 10/sup -3/ for a specific material combination. By comparing currents that yield the same probability of ignition, the relative safety factors between various material combinations may be estimated. It is found that spark ignition safety factors (current ratios) vary considerably, with cadmium requiring the lowest ignition current at each voltage. These results indicate that other materials require higher currents to initiate spark ignition in resistive circuits than does cadmium. Thus, spark ignition approval criteria may be able to be relaxed, with respect to ignition current levels, without sacrificing safety.<>
{"title":"The relative safety factors obtained by using various materials as spark electrodes in methane-air atmospheres","authors":"J. C. Cawley, J. Peterson","doi":"10.1109/IAS.1988.25227","DOIUrl":"https://doi.org/10.1109/IAS.1988.25227","url":null,"abstract":"The authors seek to quantify the influence of various common materials (copper, aluminium, brass, zinc, tin, lead and cold-rolled and stainless steels) on the probability of spark ignition in 8.3% methane-air. Results presented indicate the current necessary to produce a probability of spark ignition of 10/sup -3/ for a specific material combination. By comparing currents that yield the same probability of ignition, the relative safety factors between various material combinations may be estimated. It is found that spark ignition safety factors (current ratios) vary considerably, with cadmium requiring the lowest ignition current at each voltage. These results indicate that other materials require higher currents to initiate spark ignition in resistive circuits than does cadmium. Thus, spark ignition approval criteria may be able to be relaxed, with respect to ignition current levels, without sacrificing safety.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130723980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Studies relating mechanisms of charge creation and transport in nonpolar liquids doped with conductivity-enhancing additives are described. Most of the work concentrated on the electrolytic nature of the additives in influencing the conduction processes. Their influence on EHD motion between parallel plane electrodes is reported. Measurements have been carried out by applying voltage to metallic electrodes separated by nonpolar liquids whose conductivities were changed by varying the concentration of the additive. The results indicate that the current increases at a faster rate than the liquid velocity with increase in concentration.<>
{"title":"Some observations on electrohydrodynamic phenomena in non-polar liquids","authors":"J. Sheshakamal, J. Cross","doi":"10.1109/IAS.1988.25264","DOIUrl":"https://doi.org/10.1109/IAS.1988.25264","url":null,"abstract":"Studies relating mechanisms of charge creation and transport in nonpolar liquids doped with conductivity-enhancing additives are described. Most of the work concentrated on the electrolytic nature of the additives in influencing the conduction processes. Their influence on EHD motion between parallel plane electrodes is reported. Measurements have been carried out by applying voltage to metallic electrodes separated by nonpolar liquids whose conductivities were changed by varying the concentration of the additive. The results indicate that the current increases at a faster rate than the liquid velocity with increase in concentration.<<ETX>>","PeriodicalId":274766,"journal":{"name":"Conference Record of the 1988 IEEE Industry Applications Society Annual Meeting","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1988-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130969956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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