A Fast-Response DC Motor Speed Control System
TL;DR: In this article, the authors describe the design, construction, and testing of a speed control unit for a separately excited dc motor fed from a three-phase six-pulse fully controlled thyristor bridge.
Abstract: This paper describes the design, construction, and testing of a thyristorized speed control unit for a separately excited dc motor. The motor is fed from a three-phase six-pulse fully controlled thyristor bridge. A speed loop with a proportional plus integral controller maintains the desired speed irrespective of the load variations on the motor. An inner current control loop protects the thyristors from overcurrents. This loop also provides fast response overcoming the effect of disturbances such as variations in supply voltage. The design aspects of the control loops are discussed, and experimental results are given.
Citations
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TL;DR: In this paper, a firing scheme based on a microprocessor to control an antiparallel-connected three-phase thyristor dual converter is presented, using table-look-up algorithm to speed up the response.
Abstract: A firing scheme based on a microprocessor to control an antiparallel-connected three-phase thyristor dual converter is presented. Using table-look-up algorithm to speed up the response, it gives a full range control of the firing angle between 0° and 180° for both positive and negative current control. The maximum time delay required to correct the firing angle is one-sixth period of the ac power source. The firing angle between 120° and 180° is used for the regeneration braking to achieve the required dynamic performance in four quadrants. Built with all digital circuits with no further adjustment, this system is more reliable and has lower cost.
34 citations
TL;DR: In this article, the authors present a systematic development of the analysis, design, and testing of a SCR controlled separately excited dc motor drive system, where the motor armature voltage is supplied from a three-phase fully controlled six-pulse thyristor bridge.
Abstract: This paper presents a systematic development of the analysis, design, and testing of a thyristor (SCR) controlled separately excited dc motor drive system. The motor armature voltage is supplied from a three-phase fully controlled six-pulse thyristor bridge. Closed loop control is analyzed using transfer function techniques and the necessity of an inner current control loop is demonstrated. Armature reconnection is used to enable regenerative braking and speed reversal. Design of both a proportional and proportional integral controller is outlined and experimental results are given.
31 citations
TL;DR: In this paper, a digitally controlled current source based on a 6-pulse thyristor bridge is described, where the source is amenable to direct microprocessor control when part of a larger system, and a new method for zero voltage detection and configuration and analysis of a digital proportional-integral (PI) controller are presented.
Abstract: A digitally controlled current source, based on a 6-pulse thyristor bridge is described. When part of a larger system, the source is amenable to direct microprocessor control. Salient aspects of the design described here are a new method for zero voltage detection and the configuration and analysis of a digital proportional-integral (PI) controller. The paper gives the design procedure as well as the experimental results obtained on the actual current source.
27 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, a new synthesis method for the efficiency-optimized speed control system for the separately excited dc motor system is proposed on the basis of an improved optimal regulator theory.
Abstract: A new synthesis method for the efficiency-optimized speed control system for the separately excited dc motor system is proposed on the basis of an improved optimal regulator theory. The optimal ratio of the armature current and the field current that gives the maximum efficiency is analytically derived, and the error term of the current ratio is included in a performance index. Then, the control system which realizes both the satisfactory response and the optimal current ratio giving the optimal efficiency is constructed in the systematic design procedure. In simulational and experimental results, close agreement between them is obtained. Also, considerable improvement on the efficiency of the motor system at the steady state is obtained.
23 citations
References
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TL;DR: In this paper, a linear model for determining stability, relative stability, and dynamic response of phase-angle modulated SCR systems is presented, which is based on sampled-data control theory.
Abstract: A linear model for use in determining stability, relative stability, and dynamic response of phase-angle modulated SCR systems is presented. The model is based on sampled-data control theory and assumes 1) a system bandwidth that is small relative to sampling frequency, and 2) limited excursion of the SCR triggering angle. These assumptions are justified for practical systems. The theory leads to a simple equivalent transport-lag representation. If the triggering angle varies over a relatively wide range, a "worst-case" analysis is necessary using the linear model. An example is included to illustrate use of the model for system design and is supported by experimental data.
52 citations
"A Fast-Response DC Motor Speed Cont..." refers background in this paper
...Henceanysystemusinga thyristor poweramplifier should beregarded asasampleddatasystem inthestrict sense [ 5 ]....
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TL;DR: In this paper, the authors present some of the application considerations regarding successful utilization of SCR drives and the effects of the SCR power conversion equipment on the power distribution system with suggested approaches to certain problems that may arise, particularly as related to kilovar supply.
Abstract: A rapid growth of silicon controlled rectifier (SCR or Thyristor) dc drive applications has resulted from the many benefits derived by these equipments where adjustable speed of drive is required. These are areas normally served by conventional Ward Leonard M-G sets as well as eddy-current couplings. However, SCR drives are not exact equivalents of M-G sets and special considerations requiring some fundamental knowledge of this conversion technology must be made. This paper presents some of the application considerations regarding successful utilization of SCR drives. The paper will be divided into two parts: The first deals with the static power conversion equipment itself, its characteristics and benefits, as well as its effect on the dc drive motor. The second part deals with the effects of the SCR power conversion equipment on the power distribution system, with suggested approaches to certain problems that may arise, particularly as related to kilovar supply.
20 citations
"A Fast-Response DC Motor Speed Cont..." refers background in this paper
...Inthepastdecades, a motorgenerator (Ward-Leonard) sethasbeenusedforfeeding thedcmotor.Nowadays, thethyristor converter has replaced themotor-generator setforwell-known reasons [ 1 ]-[2]....
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