Showing papers in "IEEE Transactions on Industrial Electronics and Control Instrumentation in 1975"
TL;DR: In this article, a one-dimensional model for power transistor cooling is described and the theoretical predictions of the model are shown to be in good agreement for practical applications with three-dimensional computer simulations and experimental results.
Abstract: Differences between the measured thermal impedance of power transistors when determined by the pulsed heating curve and cooling curve techniques are discussed. These differences are shown to result primarily because the power density distributions of these devices change as devicesheat; as a result of these changes the heating curve and the cooling curve are not conjugate. It is shown that the cooling curve technique, when the cooling curve is initiated from the most non-uniform steady-state thermal, distribution, (maximum voltage, maximum power) will indicate a larger value for the thermal impedance than will the pulsed heating curve technique, even for pulses in excess of the dc power level. A one-dimensional model for power transistor cooling is described. The theoretical predictions of the model are shown to be in good agreement for practical applications with three-dimensional computer simulations and experimental results. Using this model, it is possible to estimate an average junction temperature and the area of power generation at steady-state. Both TO-66 and TO-3 encased devices of mesa and planar structures were included in this study.
95 citations
TL;DR: This paper describes a motor control circuit for a dc motor using phase-locked loop techniques to provide very accurate speed control, repeatability, and synchronization capability.
Abstract: This paper describes a motor control circuit for a dc motor using phase-locked loop techniques. The purpose of such a control loop is to provide very accurate speed control, repeatability, and synchronization capability.
39 citations
Journal Article•
TL;DR: The objective of this paper is to interpret application needs in terms of microprocessor architecture and describe some the tradeoffs available.
Abstract: Microprocessors impact many applications as they replace logic in products, act as intelligent controllers, and even carry out functions sometimes done by minicomputer systems. There is a great deal of variability among the LSI chips, microprogrammability, instruction sets, speed, their own needs and it is necessary to match the microprocessor to the application The objective of this paper is to interpret application needs in terms of microprocessor architecture and describe some the tradeoffs available.
26 citations
TL;DR: In this article, a new simple equidistant pulse firing scheme was proposed for three-phase Graetz bridge converters employing equideistant pulses for high voltage dc transmission, which is intended to be economically quite competitive to the presently existing individual phase control circuits used in 3-phase converter circuits for industrial applications.
Abstract: From the literature published, six different gate firing schemes are available for three-phase thyristor Graetz bridge converters employing equidistant pulses. All these thyristor firing schemes have been developed with particular attention to the special control requirements of converters used in a high voltage dc transmission scheme. Herein is described a new simple equidistant pulse firing scheme intended to be economically quite competitive to the presently existing individual phase control circuits used in three-phase converter circuits for industrial applications. The princidple of operation and the circuit details of the firing circuit are described. Experimental results obtained on a laboratory dc drive of capacity 3 KVA are discussed.
25 citations
TL;DR: In this article, the angular speed and torque angle of a synchronous machine are measured using a very high accuracy in a very short time and the output signals are available in a digital format suitable for direct use in an on-line digital control device.
Abstract: A device to measure the angular speed and torque angle of a synchronous machine is described Measurements of very high accuracy are made in a very short time The output signals are available in a digital format suitable for direct use in an on-line digital control device
23 citations
TL;DR: Computer analysis of the turnoff process of SCR gives better understanding of the SCR reverse current, voltage and their effect on the circuit performance.
Abstract: Analysis of the turnoff process of SCR plays an important part in the design of SCR circuits. A simple computer model is developed to simulate the SCR turnoff process. This is based on the recovered charge characteristics given in the data sheets and the empirical results. Approximations involved in the simulation of stored charge are indicated. Computer analysis gives better understanding of the SCR reverse current, voltage and their effect on the circuit performance.
21 citations
TL;DR: In this article, a digital computer-simulation study of a complex drive-system which incorporates a thyristor cycloconverter-type frequency-converter in the rotor circuit of a slip-ring induction motor for speed variation in the subsynchronous as well as the supersynchronous region by secondary voltage control is presented.
Abstract: This paper deals with a digital computer-simulation study of a complex drive-system which incorporates a thyristor cycloconverter-type frequency-converter in the rotor circuit of a slip-ring induction motor for speed variation in the subsynchronous as well as the supersynchronous region by secondary voltage control The action of the frequency converter is analogous to that of a normal commutator in the stator-fed ac commutator motor while the circuit behavior is similar to that of a cycloconverter. A rotor-position detector is used to switch the thyristor configuration in a sequential manner to generate an output voltage having a predominant slip-frequency component. Simulation involves solution of a set of generalized performance equations of an ideal induction machine in an appropriate reference frame under the control conditions imposed by the thyristor-commutator which is simulated using simple logical and limiting statements. Differential equations are solved by the well-known Runge-Kutta numerical integration method. Initial simulation results assuming thyristors as ideal switches and neglecting source impedances show very similar characteristics to the case when a pure sine-wave slip-frequency voltage is injected to the rotor. Rigorous simulation results include the physical thyristor behavior, effect of source impedances, overlap, and logical control of the circulating currents that may occur. Simulation results are presented together with the experimental performance of the drive.
20 citations
TL;DR: In this paper, the basic operational characteristics of dc-to-dc converters are analyzed and the necessary conditions for the stability of these converters were measured through analog computer simulation, and further research is suggested for the solution of the physical design of absolutely stable, reliable, and, efficient power converters of this class.
Abstract: The basic operational characteristics of dc-to-dc converters are analyzed. The basic physical characteristics of power converters are identified. A simple class dc-to-dc power converters is chosen which could satisfy any set of operating requirements. Three different controlling methods in this class are described in detail. Necessary conditions for the stability of these converters are measured through analog computer simulation. These curves are related to other operational characteristics, such as ripple and regulation. Finally, further research is suggested for the solution of the physical design of absolutely stable, reliable, and, efficient power converters of this class.
19 citations
TL;DR: Using the concept of hanging nodes and hanging branches, the open-circuited branches are removed from the circuit to get a modified reduced incidence matrix and the problem of instability associated with numerical integration is eliminated.
Abstract: Computer analysis of SCR circuits is developed on the basis of topological considerations. Using the concept of hanging nodes and hanging branches, the open-circuited branches are removed from the circuit to get a modified reduced incidence matrix. This concept eliminates the problem of instability associated with numerical integration. Flow charts are discussed and computed results of a chopper circuit are presented.
18 citations
TL;DR: In this paper, the capabilities and limitations of a modem solid-state microwave Doppler radar used for monitoring the flow rates of moving materials are discussed, and it has been concluded that the average frequency is proportional to the average bulk velocity.
Abstract: This paper contains a discussion of the capabilities and limitations of a modem solid-state microwave Doppler radar used for monitoring the flow rates of moving materials. Experimental results Of monitoring flow rates of paritculate solids are presented. It has been concluded that the average Doppler frequency is proportional to the average bulk velocity. When the bulk density and the crosssectional area of the pipe are known, the system-provides contactless means of-monitoring the mass flow rate of particulate solids.
17 citations
TL;DR: In this paper, a novel trigger control scheme for thyristors operating under variable-frequency anode supply is described, which uses a zero crossing detector and a novel time delay circuit.
Abstract: A novel trigger control scheme for thyristors operating under variable-frequency anode supply is described. The scheme uses a zero crossing detector and a novel time delay circuit. A few applications are suggested.
TL;DR: In this article, current sharing in multiple parallel power diode assemblies highlights the significance of bus-bar inductance and some mutual inductances are demonstrated to be advantageous and practical design guidelines for multiple parallel diode rectifiers are given.
Abstract: Analysis of current sharing in multiple parallel power diode assemblies highlights the significance of bus-bar inductance. Some mutual inductances are demonstrated to be advantageous and practical design guidelines for multiple parallel diode rectifiers are given.
TL;DR: A general digital computer program for the analysis of chopper-fed dc separately and series excited motors and the derivation of relevant equations (for each mode) and therefore, any chopper circuit can be analyzed.
Abstract: The paper describes a general digital computer program for the analysis of chopper-fed dc separately and series excited motors. The program does not require the prior knowledge of modes of operation of chopper circuit and the derivation of relevant equations (for each mode) and therefore, any chopper circuit can be analyzed. The different techniques have also been incorporated to make the computation fast.
TL;DR: In this article, the phase portrait for a stepping motor with fast current buildup drive is developed and the shape of the trajectories depends on dimensionless load torque and damping ratio but reflects changes in load torque, inertia, damping and stator current.
Abstract: The phase portrait for a stepping motor with fast current buildup drive is developed. The shape of the trajectories depends on dimensionless load torque and damping ratio but reflects changes in load torque, inertia, damping and stator current. Motor stepping failures occur when the response crosses separatrices in the phase plane during the stepping sequence. Many modes of stepper failure during start-stop or slewing sequences or underload are explained by the phase portrait for the motor and drive. In addition, the global picture of response obtained from the aalysis is useful in developing slewing strategies and evaluating unusual step command sequences.
TL;DR: In this article, the performance characteristics of solid state dc series motor drives under phase control and current control schemes are investigated. And the peak current and ripple content which affect the commutating capability of the motor are also investigated.
Abstract: This paper is concerned with the detailed study of the performance characteristics of solid state dc series motor drives under phase control and current control schemes. The drive systems with the control schemes are simulated on a digital computer. An efficient time saving method is employed for computation. Different modes of operation are considered. The performance characteristics, such as, speed-torque, input harmonic content and input power factor variations are obtained and compared for the two types of control schemes. The peak current and ripple content which affect the commutating capability of the motor are also investigated. Current control scheme looks promising over the commonly used phase control scheme. Experimental results demonstrate the feasibility and verify the basic principles of operation.
TL;DR: Recent advances in SCR blocking voltage capability are making the complementary impulse commutated current source inverter a viable competitor.
Abstract: A current source inverter combined with a controlled slip induction motor is a reliable and rugged ac drive system. The majority of the inverters in use today are the voltage source type using auxiliary impulse commutation. However, recent advances in SCR blocking voltage capability are making the complementary impulse commutated current source inverter a viable competitor
TL;DR: In this article, it is shown that using an approximate-analog model of dead time synthesized from relatively inexpensive electronic components, a controller using the linear predictor approach is quite practicable in a typical process conatrol situation.
Abstract: The control of a process characterized by major " pure time delay" or " transport lag" by means of a coentonal analog controller is difficult because of the finite time which must elapse before a change in the controller output produces any measurable change in the process output. Linear predictor control is a well-known theoretical scheme for compensating the dead time; this requires incorporation of dead time in the controller itself and hardware difficulties have limited the use of this scheme in practice. It is shown in this paper that using an approximate-analog model of dead time synthesized from relatively inexpensive electronic components, a controller using the linear predictor approach is quite practicable in a typical process conatrol situation. A design of a control scheme for a laboratory process implementing the linear predictor control principle is given and it is shown that the improvement obtained in the control of the process, using an approximate analog model of dead time, is considerable.
TL;DR: In this article, a number of load waveforms, produced by switching elements in a single-phase supply to a resistance load, are analyzed and the power factor of the circuit is investigated and its relationship to power, distortion factor and fundamental power factor given.
Abstract: A number of load waveforms, produced by switching elements in a single-phase supply to a resistance load, are analyzed. The power factor of the circuit is investigated and its relationship to power, distortion factor and fundamental power factor given. A number of particular switching modes are introduced to give leading power factors and certain harmonic elimination.
TL;DR: In this article, a non-linear electronic compensator (N-L.E.C), based on the synthesis of the dual-input describing function (DIDF), is proposed.
Abstract: The technique for the synthesis of the dual-input describing function (DIDF) is introduced here and the construction of a non-linear electronic compensator (N-L.E.C.), based on this techniques, is proposed. The above non-linear network is used to compensate . linear and non-linear systems for instability, limit Cycles, speed of response and the static accuracy. Four practical examples are given at the end of this work.
TL;DR: In this paper, thermoelectric modules are used for active bimodal control of the SIMS II Strapdown Inertial Navigator with dc current and a worst hot-case coefficient of performance of 0.56 was measured.
Abstract: Current technology has produced high-performance semiconductor thermoelectric modules that can be a design option for temperature control of electronics and instrumentation. It seems reasonable that their advantages would be helpful to electronics and process control designers who may not be aware of the tremendous advances in the state-of-the-art of thermoelectrics. When dc current is available, thermoelectrics can be used for active bimodal control. This paper describes their fundamental operation, derives some performance relationships, and presents computation techniques for their integration into a system. An example is given where thermoelectrics were used to temperature control the SIMS II Strapdown Inertial Navigator designed by the Charles Stark Draper Laboratory. Test results showed that temperature control of the gyros and accelerometers was achieved to ±0.1°F in ambients between -20°F and 120°F. A worst hot-case coefficient of performance of 0.56 was measured where a 240-watt load at 79°F was moved across a 50°F gradient using 425 watts of thermoelectric power.
TL;DR: In this article, a controller is described which incorporates a microprocessor to reduce the necessity of operator intervention, increase overall capability and provide for easy expansion or improvement of control in the future.
Abstract: The metals rolling industry has for many years benefited from the use of automatic thickness controllers to produce a more uniform and salable product. Yet non-computer-based controllers have normally required operator adjustment in order to produce the best possible results over the full range of metal thickness, width, alloy and temper. A controller is described which incorporates a microprocessor to reduce the necessity of operator intervention, increase overall capability and provide for easy expansion or improvement of control in the future. The microprocessor not only performs all computations required for control but modifies its operation based on information supplied to it by a companion thickness measurement system.
TL;DR: In this paper, a unified approach to obtain the steady-state solutions for some inverter circuits is presented, and it is also proved that these systems actually exhibit a stable limit cycle phenomena.
Abstract: This paper presents an unified approach to obtain the steady-state solutions for some inverter circuits. It is also proved incidentally that these systems actually exhibit a stable limit cycle phenomena.
TL;DR: In this article, the output time period of a multivibrator is found to be linearly related with the coupling capacitance of the circuit, and the proposed circuit is realizable in IC form, minimizing the problems of shielding and stray capacitance if placed very close to the capacitive transducers.
Abstract: The work presented is a study of Emitter Coupled Astable Multivibrator. The output time period of this multivibrator is found to be linearly related with the coupling capacitance of the circuit. After the study of the circuit performance, thfe authors suggest that it can be used to obtain a signal conveying the information sensed by capacitive sensors. Also the signal is easy to be ransmitted and measured. The proposed circuit is realizable in IC form, minimizing the problems of shielding and stray capacitance if placed very close to the capacitive transducer.
TL;DR: An algorithm for the generation of a modified proper tree and fundamental cutset matrix from a network graph is developed, which utilizes much less computer storage space and computation time compared to the classical methods.
Abstract: The purpose of this article is to develop an efficient model for the analysis of a three-phase converter. An algorithm for the generation of a modified proper tree and fundamental cutset matrix from a network graph is developed, which utilizes much less computer storage space and computation time compared to the classical methods. A three-phase rectifier bridge with its associated protective circuits is considered and the results obtained from the developed technique are discussed.
TL;DR: In a two-branch resistive CirGcuit where each branch current is independently controlled by a pair of inverse-parallel-connected thyristors, the overall power factor is given by a relationship that appears to be true in all cases as mentioned in this paper.
Abstract: In a two-branch resistive CirGcuit where each branch current is independently controlled by a pair of inverse-parallel-connected thyristors the overall power factor, seen from the supply terminals, is given by a relationship that appears to be true in all cases
TL;DR: In this paper, the d-and q-axis field excitation voltages are controlled to provide characteristics that combine the advantages of both syLchronous and induction machines, with the aid of the phasor diagram, and expressions for the synchronous and asynchronous components of the armature voltage, the active and reactive powers, and torque.
Abstract: The paper considers the control and the behavior of an asychronized synchronous machine. The d- and q-axis field excitation voltages are controlled to provide characteristics that combine the advantages of both syLchronous and induction machines. The properties are described with the aid of the phasor diagram, and expressions are presented for the synchronous and asynchronous components of the armature voltage, the active and reactive powers, and the torque. Experimental results for a 2 kVA machine are compared with calculated results for both steady-state and transient operation, and the action of the novel excitation system is described.
TL;DR: In this article, the location of boundaries of images projected on a discrete array of photosensors or scanned by a television camera is detected using a model developed for the detection system and it is shown that proper application of a triangular perturbation signal can yield a linear transfer characteristic between the actual boundary location and the detector output
Abstract: This paper is concerned with accurate detection of the location of boundaries of images projected on a discrete array of photosensors or scanned by a television camera A model is developed for the detection system and it is shown that proper application of a triangular perturbation signal can yield a linear transfer characteristic between the actual boundary location and the detector output
TL;DR: The most common approach to microcomputer software development is to first assemble the program on the microcomputer system or cross-assemble it on a larger computer; then debug the program in the micro computer or simulate it on another computer; and finally burn the program into a ROM or PROM.
Abstract: The most common approach to microcomputer software development is to first assemble the program on the microcomputer system or cross-assemble it on a larger computer; then debug the program in the microcomputer or simulate it on another computer; and finally burn the program into a ROM or PROM.
TL;DR: In this article, a modified version of the chopper circuit has been suggested and analyzed, and the releveant points of difference between the modified circuit and the original one have been indicated.
Abstract: In a companion paper, the analysis and design of a commonly used chopper circuit for controling the speed of slip-ring induction motor has been given. In order to overcome the disadvantages of that circuit, a modified version of the chopper circuit has been suggested and analyzed. The releveant points of difference between the design of the modified circuit and the original one have been indicated. Also the comparative merits and demerits of the two circuits have been discussed.