Showing papers in "IEEE Transactions on Industrial Electronics and Control Instrumentation in 1981"
TL;DR: A microprocessor-based implementation of the sampling wattmeter is described, which measures the voltage waveform period and computes the sampling interval and number of samples and reads out as a 4-digit display of average power.
Abstract: A microprocessor-based implementation of the sampling wattmeter is described. The measurement process is in two parts. First, the microprocessor measures the voltage waveform period and computes the sampling interval and number of samples. The measurement of average power then takes place over an integer number of cycles. Digitized samples of the voltage and current waveforms are multiplied together and the products accumulated over the measurement period. The sum is divided by the number of samples, scaled, and read out as a 4-digit display of average power.
50 citations
TL;DR: The problems and prospects of electric motors for space applications are given and brushless dc motors and stepper motors, which are widely used, are discussed in detail.
Abstract: Spacecrafts rely on electric motors for Important functions such as attitude control, deployment mechanisms, throttle valve control, etc. Electric motors for space applications must have long life and high reliability, under high vacuum, radiation, and wide operating temperature environments. Although various types of motors are available, all of them are not suitable. Limitations of ac synchronous motors and brushes and commutators of conventional dc motors are given. Brushless dc motors and stepper motors, which are widely used, are discussed in detail. Problems of conventional lubrication and bearings and the advantages of magnetic bearings are also discussed. In a totally noncontacting system, such as a brushless dc motor/stepper motor with magnetic bearing, life and reliability are functions of only electronic components, and they can be improved to the desired level. Thus this paper gives the problems and prospects of electric motors for space applications.
37 citations
TL;DR: In this article, an extension of the subharmonic method for PWM systems, in the case in which the ratio between modulating and carrier wave amplitudes can be varied from 0 to?, is studied in an analytical way.
Abstract: In this paper the extension of the subharmonic method for pulse-width modulation (PWM) systems, in the case in which the ratio between modulating and carrier wave amplitudes can be varied from 0 to ?, is studied in an analytical way. This method allows us to obtain an inverter output waveform variable continuously from a nearly sinusoidal to a square wave and to increase somewhat the amplitude of the fundamental output wave without a significant worsening of the harmonic content, a feature particularly useful for drives with wide speed variations or which need an optimized use of dc power supply.
36 citations
TL;DR: In this paper, a power converter with reversible power flow is presented, which transforms polyphase ac or dc power of one form and voltage level to ac or DC power of another form and Voltage level, using a modulated highfrequency link between two sets of matrices of switches at the output terminals.
Abstract: A power converter with reversible power flow, which transforms polyphase ac or dc power of one form and voltage level to ac or dc power of another form and voltage level, is presented. Use of a modulated high-frequency link between two sets of matrices of switches at the output terminals allows the application of active filtering processes and the elimination of all low-frequency filters and transformers; it allows, furthermore, arbitrary and independent programming of the power factors at the two ports. Low weight and cost of apparatus is enhanced by the time proven reliability of its significant functional elements. The potential for the construction of megawatt capacity systems is derived from experience with the basic class of these converters and is reinforced by the report of reduction to practice of some of the described techniques in the form of a 3-kW model in a companion paper [15].
31 citations
TL;DR: The 50-percent duty ratio instability is analyzed for each power cell configuration and canonical small signal models are given and verified in the case of an MC2 buck regulator, verified by application of the least square measurement technique.
Abstract: High power distribution in continuous or pulsed mode on board application satellites has drastically complicated the design of power conditioning regulators by requiring the reliable operation with brilliant dynamic behavior of complex modular structures to satisfy their powerful loads. Current control modulators satisfy these requirements by the energy control capability. The 50-percent duty ratio instability is analyzed for each power cell configuration and canonical small signal models are given and verified in the case of an MC 2 buck regulator. The model validation is verified by application of the least square measurement technique which allows the accurate determination of any transmittance of the closed loop system.
29 citations
TL;DR: In this article, a microprocessor-based algorithm for steady-state and dynamic control of a modified six-pulse converter with two neutral-connected auxiliary thyristors is described.
Abstract: A microprocessor-based algorithm for steady-state and dynamic control of a modified six-pulse converter with two neutral-connected auxiliary thyristors is described. The algorithm which is applicable to the standard six-thyristor bridge is experimentally verified and is found to give a very fast, precise, and equidistant control of the thyristor triggerings. This paper describes the operation of the modified bridge, the control algorithm and the microprocessor implementation, and gives the bridge transfer function and dynamic response.
22 citations
TL;DR: In this paper, a parallel-plate capacitor has been used as the sensing transducer for the measurement of moisture content in concrete and soil, and the instrument is compact, reliable, inexpensive, and gives consistent results over an extended life-testing period.
Abstract: The paper deals with an instrument which has been developed for the measurement of moisture content in concrete and soil. A parallel-plate capacitor has been used as the sensing transducer. The instrument is compact, reliable, inexpensive, and gives consistent results over an extended life-testing period.
18 citations
TL;DR: In this paper, the voltage and current harmonics introduced by a single-phase triac ac controller can be significantly reduced by shunting the triac with a fixed-value resistance, and theoretical results are given for a purely resistive load and a fixed RL load with a power factor of 0.7.
Abstract: This paper shows that the voltage and current harmonics introduced by a single-phase triac ac controller can be significantly reduced by shunting the triac with a fixed-value resistance. Theoretical results are given for a purely resistive load and a fixed RL load with a power factor of 0.7, to substantiate this claim.
18 citations
TL;DR: In this article, a generalized firing angle controller using a phase-locked loop, for control of thyristors is described, which can operate over a wide range of supply frequencies and is immune to the transients and harmonic distortions in the supply voltage.
Abstract: A generalized firing angle controller using a phase-locked loop, for control of thyristors is described. Different types of firing angle variation characteristics are possible because of the generalized phase detector used in the circuit. The controller can operate over a wide range of supply frequencies and is immune to the transients and harmonic distortions in the supply voltage. Also changes in the supply voltage amplitude do not have any effect on the firing angle. The same circuit can be used to provide firing pulses for three- or six-element thyristor configurations. The scheme can be successfully used for thyristor converters and cycloconverters.
18 citations
TL;DR: In this article, a new ac voltage regulator was proposed which employs thyristors as switching elements in the secondary of a power autotransformer, which employs the switching element as switching element in a power auto-transformer.
Abstract: A new ac voltage regulator is proposed which employs thyristors as switching elements in the secondary of a power autotransformer.
15 citations
TL;DR: In this article, the authors demonstrate and analyze an oscillatory process in three dimensions, which is related to the dynamic behavior of a well-known symmetrical quadrature oscillator in two phases.
Abstract: Oscillatory processes in two dimensions are well known, and most of the electronic oscillators exhibit a dynamic behavior, which is related to them. The aim of the present paper is to demonstrate and analyze an oscillatory process in three dimensions. The mathematical model considered possesses, as solutions in steady state, three stable sinusoidal waveforms arranged symmetrically as is usual in a three-phase supply system. The dynamic behavior of the model is thoroughly investigated and it is shown that it is related to the dynamic behavior of a well-known symmetrical quadrature oscillator in two phases. This relationship suggests that a practical system realized according to the model equations should possess the properties of a high-quality quickly responding voltage-controlled oscillator (VCO). This useful feature has been demonstrated experimentally by investigating the performance of a corresponding instrument.
TL;DR: In this article, a computer-based piece-wise linear technique was used to analyze the dynamic performances of an armature voltage-controlled chopper circuit with a low-pass input filter taking the account of nonlinearities such as the magnetic saturation and the product of variable terms.
Abstract: This paper uses a computer-based piece-wise linear technique to analyze the dynamic performances of an armature voltage-controlled chopper circuit with a low-pass input filter taking the account of nonlinearities such as the magnetic saturation and the product of variable terms. The performances in the transient conditions which occur in practical situations are predicted by a computer model and are compared with the practical measurements.
TL;DR: In this paper, a modified direct-decoupling method using the adjoint matrix instead of the inverse of the plant matrix to construct the compensator was proposed, which uses a frequency-domain model-reduction method to simplify the degree of the given plant transfer function matrix and the obtained compensator.
Abstract: A design method, which decouples an interactive system by using a compensator obtained from the plant inverse matrix, which is often called the direct-decoupling method is modified in this paper. The modified direct-decoupling method uses the adjoint matrix instead of the inverse of the plant matrix to construct the compensator. The method uses a frequency-domain model-reduction method to simplify the degree of the given plant transfer function matrix and the obtained compensator. For an open-loop stable multivariable system, the proposed method gives a simple, practical, and realizable controller without using an unstable pole-zero cancellation approach.
TL;DR: In this paper, a microprocessor-based digital PLL speed control system for motor drives is discussed on its load characteristics, stability, and speed control accuracy, and two compensating methods, that is, the current compensator and the speed feedback loop are proposed for enlarging both static and dynamic operating load torque ranges of the PLL-controlled motor.
Abstract: A microprocessor-based digital PLL speed control system for motor drives is discussed on its load characteristics, stability, and speed control accuracy. The digital and hybrid simulations as well as the Z transform are used to analyze these items of discussion. As the results of the analysis, two compensating methods, that is, the current compensator and the speed feedback loop are proposed for enlargement of both static and dynamic operating load torque ranges of the PLL-controlled motor. This effect of the compensators is predicted through theoretical procedures, assessed by the hybrid simulator, and confirmed by experiments. The effects due to the current compensator and the speed feedback loop on the stability and the speed control accuracy of the PLL system are inspected with the aid of digital and hybrid simulations. These compensators do not virtually affect the stability of the PLL system. The speed control accuracy of the PLL system can be increased by virtue of the speed feedback loop. Design examples based on the discussion in this paper are provided and the authors conclude that the methods for performance improvement have substantial effects on the practical design for the microprocessor-based digital PLL speed control system.
TL;DR: In this article, the state equations of the super synchronous Scherbius induction motor system and the commutatorless motor are established for the synthesis of a speed control or torque control system using modern control theory and the microprocessor as a controller.
Abstract: The state equations of the super synchronous Scherbius induction motor system and the commutatorless motor are established for the synthesis of a speed control or torque control system using modern control theory and the microprocessor as a controller. In addition, signal delays due to the processing time required to execute the employed control algorithm in a microprocessor and the effect of filters inserted in feedback loops in order to eliminate harmonics are considered.
TL;DR: In this article, an efficient ac-to-dc converter with reversible power flow is presented, which embodies an active, low-frequency filter, and is governed by a pulse area control mechanism with a verified response time of one 10-kHz cycle, or 100 µs.
Abstract: An efficient ac-to-dc converter with reversible power flow, which embodies an active, low-frequency filter, is presented. A nondissipatively controlled, nonlinear resonant oscillator is used to extract electric energy directly from the phase pairs of the polyphase supply line and to generate a mixed amplitude-and frequency-modulated carrier. The demodulated carrier and the resulting 20-kHz pulse train produces, after being processed by a high-frequency filter, an active, low-frequency filtering effect for attenuation of the 360-Hz ripple of the apparently ``rectified'' three-phase supply line. The system is governed by means of a pulse area control mechanism with a verified response time of one 10-kHz cycle, or 100 µs. The customary dc link between the three-phase line and the converter's 20-kHz pulse-processing mechanism in the form of a common rectifier-filter is completely eliminated. Data obtained from the test of a 3-kW feasibility model are analyzed in support of the presentation of the significant aspects of design and technology.
TL;DR: In this paper, design curves are presented from which the individual harmonics generated at the input to a dc-dc chopper can be determined and the effect of the chopper output ripple current on the input harmonics is included.
Abstract: Design curves are presented from which the individual harmonics generated at the input to a dc-dc chopper can be determined. The effect of the chopper output ripple current on the input harmonics is included. These generalized curves can be used to determine the input filter component ratings as well as to compute the harmonics injected into the source. Using harmonic superposition, the input current and voltage waveforms as a function of time are determined and thus the peak voltages and current stresses are obtained. A practical example illustrates the use of the curves and serves to verify the analysis.
TL;DR: In this paper, the authors deal with the transient analysis of a dc series motor with three models: linear, nonlinear, and nonlinear with armature reaction, and the results show a big difference in the transient response for these models.
Abstract: The paper deals with the transient analysis of a dc series motor. The analysis includes starting, load changing, and braking. Three models were considered: linear, nonlinear, and nonlinear with armature reaction. The results show a big difference in the transient response for these models and indicate the necessity of using a nonlinear model for accurate simulation of the series motor. The analysis was performed with the aid of the SUPER SCEPTRE computer program.
TL;DR: In this article, the authors presented a comprehensive analysis of the performance of a dc-series motor during regenerative braking operation, taking into account all the possible modes of operation during this type of braking, the nonlinearity of the magnetization characteristics including the variation of the field inductance, and the effect of the commutating capacitor in the chopper circuit.
Abstract: This paper presents a comprehensive analysis which predicts the performance of a thyristor-chopper controlled dc series motor during regenerative braking operation. The analysis takes into account all the possible modes of operation during this type of braking, the nonlinearity of the magnetization characteristics including the variation of the field inductance, and the effect of the commutating capacitor in the chopper circuit on the braking performance. It is shown from the computed results that above a critical speed, the value of the commutating capacitor sets a maximum value of mark/space ratio of the chopper regulator beyond which the regenerative braking operation fails. Typical test results on a practical system are shown to agree with the computed results.
TL;DR: In this article, a method to stabilize a phase-locked loop (PLL) dc motor control system is described, where the Integral Square Error (ISE) criterion is used to find out the constants of the stabilizing circuit for giving an optimum response.
Abstract: A method to stabilize a phase-locked loop (PLL) dc motor control system is described. Integral square error (ISE) criterion is used to find out the constants of the stabilizing circuit for giving an optimum response. Transient response of the system is calculated for a sudden loading condition and changes in reference frequency. Experimental oscillograms are also included.
TL;DR: An adaptive time-optimal feedback controller is investigated which is capable of updating model parameters during normal system operation, and design methods are presented for continuous-time as well as discrete-time controllers.
Abstract: Time-optimal feedback controllers are studied for systems with delay in control. The control input is assumed to be bounded. Design methods are presented for continuous-time as well as discrete-time controllers. Sensitivities of the control system performance due to mismatches between the model and the plant are also studied. Finally, an adaptive time-optimal feedback controller is investigated which is capable of updating model parameters during normal system operation.
TL;DR: In this article, two typical motor control systems are studied; one is based on frequency comparison, and the other on the use of a phase-locked loop and the results show that the sampling period has a stable region when the system constants and the controller parameters are given.
Abstract: This paper investigates the stability and sampling problems in the microcomputer-based motor control systems. When a microcomputer is used to perform the control algorithm and to monitor the motor speed, the sampling rate and the controller parameters must be chosen so that the sampled-data system is stable. In this paper, two typical motor control systems are studied; one is based on frequency comparison, and the other on the use of a phase-locked loop. The result shows that the sampling period has a stable region when the system constants and the controller parameters are given. The paper also reveals the information for determining the measuring time and the controller parameters.
TL;DR: In this paper, a speed control system with a separately controlled current source converter was proposed for a doubly fed synchronous motor, which has the advantages of a simple frequency converter construction and a wide-range speed control capability from standstill to supersynchronous speeds.
Abstract: A speed-control system with a separately controlled current source converter is proposed for a doubly fed synchronous motor. Conventional systems with a voltage-source converter develop negative damping torques and become unstable. The theoretical analysis for a linearized model shows that the proposed system eliminates negative damping torques. The digital simulation of a nonlinear model and experiments using a laboratory machine verify the theoretical predictions. The system has the advantages of a simple frequency converter construction and a wide-range speed control capability from standstill to supersynchronous speeds.
TL;DR: In this paper, the authors derived necessary and sufficient conditions for the small-signal stability of forward (buck-type) switched-mode power supplies with a constant switching frequency in the continuous conduction mode.
Abstract: Necessary and sufficient conditions are derived for the small-signal stability of forward (buck-type) switched-mode power supplies with a constant switching frequency in the continuous conduction mode. It is shown that the maximum allowable gain of the error amplifier is a function of the modulation process, the duty cycle of the switch, and the filter elements of the supply. Under certain conditions, the gain can be made infinitely large. This can occur for duty cycles less than 50 percent if the end of the ``on'' time is modulated and for duty cycles between 50 and 100 percent if the start of the ``on'' time is modulated. Excellent agreement with computer simulations and laboratory measurements has been observed.
TL;DR: In this article, a Z80 microcomputer-based control system for the cascaded single-phase rectifier circuit is presented, which uses the microcomputer to generate the required firing pulses to the thyristors and to monitor the commutating process.
Abstract: A Z80 microcomputer-based control system for the cascaded single-phase rectifier circuit is presented. The cascaded rectifier circuit is composed of two thyristor bridges, that is, one is the conventional bridge and the other thyristor bridge with forced commutation. This circuit configuration is adopted to improve the input power factor. The system uses the microcomputer to generate the required firing pulses to the thyristors and to monitor the commutating process. Once the commutation failure is detected, the gating sequence is changed to return the system to the normal condition, thus realizing the commutation failure-free thyristor converter.
TL;DR: A novel system configuration technique using microprocessors is proposed and it is proposed that such a flexible system design or adaptable modification of characteristics by only memory change or program revision with the hardware intact is proposed.
Abstract: Digital control of static power converters such as pulsewidth modulated (PWM) inverter realizes the precise waveform control which copes with interference problems by selective elimination of harmful harmonics not only in load voltage but also in source current. Moreover, software control has a great advantage in allowing such a flexible system design or adaptable modification of characteristics by only memory change or program revision with the hardware intact. In this paper, a novel system configuration technique using microprocessors is proposed.
TL;DR: In this article, the design of a miniature, recording cardiotachometer is described, and a hand-held display is used to evaluate the performance of the cardiachometer.
Abstract: The design of a miniature, recording cardiotachometer is described. It is simple and can store digital data. Bench and field tests, using a hand-held display, are presented. Construction and principles of operation are discussed. Applications, with performing athlete subjects, are outlined.
TL;DR: The Remote Link Unit is an advanced remote terminal which provides a complete interface between a CPU and remote subsystems, and an intelligent Link Manager which maintains control over the LM's and supervises communications with the CPU.
Abstract: The Remote Link Unit (RLU) is an advanced remote terminal which provides a complete interface between a CPU and remote subsystems. The RLU consists of several intelligent Link Modules (LM) which provide the direct interfaces to the subsystems, and an intelligent Link Manager (LMG) which maintains control over the LM's and supervises communications with the CPU. By implementing the RLU with a hierarchy of specialized processors, it is possible to achieve with the RLU highly efficient, reliable, and flexible operation.
TL;DR: It is proved that one controlled rectifier supplying a bridge inverter performs similarly to a conventional cycloconverter if the converter output-voltage modulation and the inverter switching sequency are synchronized.
Abstract: This work explains the concept of a simple cycloconverter. It is proved that one controlled rectifier supplying a bridge inverter performs similarly to a conventional cycloconverter if the converter output-voltage modulation and the inverter switching sequency are synchronized. While the required firing system remains almost unchanged, the number of power solid-state components is significantly reduced. A three-phase 1-to 5-Hz 5-kVA unit was built and typical oscillograms are presented.
TL;DR: In this paper, the design and implementation of a controller to stabilize a single-input single-output (SISO) unstable plant using pole-assignment technique and observer theory is considered.
Abstract: This paper considers the design and implementation of a controller to stabilize a single-input single-output unstable plant using pole-assignment technique and observer theory. First, assuming that the state variables are available for feedback, the pole-assignment technique is used to determine the feedback gains required to achieve a desired set of closed-loop poles. This assumption is relaxed and an observer is designed to estimate the control law using output feedback. The unstable plant is simulated on a TR48 analog computer with the controller in the feedback loop. Active network implementation of the controller is discussed.