Thyristor converter-fed synchronous motor drive
TL;DR: In this article, the development, design and construction of a variable speed drive using a synchronous motor is described, and the digital simulation based on simplified block diagram is accurate enough for obtaining the responses of the system to step changes in speed reference and load on motor.
Abstract: The development, design and construction of a variable speed drive using a synchronous motor is described in this paper. At first, the operation of motor with a current-fed, motor e. m. f. commutated inverter is explained. The working of control circuitry is explained next with the aid of logic and functional blocks. The power circuit, comprising the converter, inverter and motor has been reduced to simple blocks so that the controller design by hand computations becomes possible. It has also been shown that the digital simulation based on simplified block diagram is accurate enough for obtaining the responses of the system to step changes in speed reference and load on motor.
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TL;DR: In this article, a steady-state analysis of a three-phase induction motor fed by a DC link inverter commutated by machine-induced EMF is presented, where the active power requirement of the motor is met by the DC link, and the necessary reactive power is supplied by a capacitor bank connected at the motor terminals.
Abstract: A steady-state analysis of a three-phase induction motor fed by a DC link inverter commutated by machine-induced EMF (electromotive force) is presented. The active power requirement of the motor is met by the DC link, and the necessary reactive power is supplied by a capacitor bank connected at the motor terminals. A generalized analytical model is developed for no-load as well as loaded conditions of the motor. The steady-state performance of the motor is numerically evaluated. The computed results are compared with corresponding experimental results for a 4 HP squirrel cage induction motor. The relevant oscillograms of voltage and current waveforms of the inverter and motor are presented and discussed. >
17 citations
01 Jan 2013
TL;DR: In this paper, a brushless DC motor drive system with input shaping using classical control theory is analyzed using time response analysis and the relative stability of this drive system is determined by Bode Plot.
Abstract: The main objective of this work is to analyze the brushless DC (BLDC) motor drive system with input shaping using classical control theory. In this paper, different values of damping ratio are used to understand the generalized drive performance. The transient response of the BLDC motor drive system is analyzed using time response analysis. The dynamic behaviour and steady state performance of the BLDC motor drive system is judged and compared by its steady state error to various standard test signals. The relative stability of this drive system is determined by Bode Plot. These analysis spotlights that it is possible to obtain a finite-time setting response without oscillation in BLDC motor drive by applying input in four steps of different amplitude to the drive system. These analyses are helpful to design a precise speed control system and current control system for BLDC motor drive with fast response. The Matlab/Simulink software is used to perform the simulation. V : q-axis equivalent stator voltage in volts r qs i : q-axis equivalent stator current in amps s L : Equivalent stator self-inductance in henry s R : Equivalent stator winding resistance in ohms P : Number of poles of motor L T : Load torque of motor in N-m m B : Motor viscous friction coefficient in N-m/rad/sec m J : Rotor inertia of motor in Kg-m 2
6 citations
TL;DR: In this paper, a microprocessor-based firing control scheme for the constant firing angle of the thyristors of the line commutated converter under a variable frequency source is presented.
4 citations
01 Jan 2014
TL;DR: In this paper, the root locus and root contours of the BLDC drive system are portrayed in order to focus on the complete dynamic response of the system and the steady state performance of the drive system has been investigated by calc ulating its steady-state error to various standard test signals.
Abstract: The demands for BLDC motor drives in industrial applications are rapidly increasing due to its high efficiency, high power factor and lower maintenance . Therefore, it is necessary to design a stable con trol system for BLDC drive system to achieve a quality p erformance. The stability is a major problem in the closed loop BLDC drive system which may cause oscillations of constant or changing amplitude. This paper spotlights the movements of characteristic ro ots of the drive system on s-plane with the variati on of system parameter gain ‘k’. The root locus and root contours of the BLDC drive system are portrayed in this paper which focuses the complete dynamic response of the system. Finally, the steady-state performance of the BLDC drive system has been investigated by calc ulating its steady-state error to various standard test signals. These analyses help a designer to easily v isualize the effects of varying various system para meters on root locations. These analyses give good potenti al design specifications for the control engineers. The Matlab software package is used to analyze the resu lts.
1 citations
TL;DR: The optimal control system of BLDC motor drive is a design which spotlights in this paper based on quadratic performance index and helps to realize the BLDC system with practical components.
Abstract: The application of BLDC
motor drives in industries is becoming more popular nowadays. An error will
occur in the drive that is originated by some disturbances which are the major
problems to reduce the stability of the system. To obtain the minimum
performance index, the optimal control signal is formulated, which is the main
objective of this paper. Based on quadratic performance index, the optimal
control system of BLDC motor drive is a design which spotlights in this paper.
The complexity of the mathematical expressions has been reduced by using state
space approach to the BLDC system. The burden to the control engineers has
reduced based on tedious computation by using thus optimal design. To provide
the desired operating performance, this optimal design helps to realize the
BLDC system with practical components.
1 citations
Cites methods from "Thyristor converter-fed synchronous..."
...In the next method of regulating the system output modification cannot achieve the time optimal operation [6]-[8]....
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TL;DR: In this article, a load-commutated inverter consisting of two bridges connected in parallel is used to provide two-way power flow by reversing the dc current. But the control system described does not use shaft position sensing, but senses the motor terminal voltage and the ac line current to determine the motor internal operating conditions.
Abstract: Synchronous motor drives are beginning to enjoy renewed popularity for certain applications such as flywheel energy storage. One of the reasons is that a synchronous motor drive can be made self-commutating so that the inverter becomes equivalent to a conventional phase-control bridge converter without large commutating components. The drive to be controlled consists of an inductor alternator coupled to a flywheel that will be used for temporary energy storage. The flywheel speed will vary over a two-to-one range; thus full performance can be achieved using a load-commutated inverter. A simple auxiliary commutating circuit is provided only for initial starting. The drive must operate both from a fixed dc voltage source (battery) and from a variable dc voltage source (dc motor), as it is intended for use in a battery-powered vehicle for load leveling. The load-Commutated inverter consists of two bridges connected in parallel so as to provide two-way power flow by reversing the dc current. The control system described does not use shaft position sensing, but senses the motor terminal voltage and the ac line current to determine the motor Nare internal operating conditions. This control method maintains the silicon-controlled rectifier (SCR) turn-off time as a constant percentage of the period of the generated back electromotive force (EMF) as speed and current are varied during operation. The inverter turn-off time is thus maintained by feedback control rather than the use of special function generators. A 20-kVA laboratory development drive system has been built and successfully tested using this control strategy.
58 citations
TL;DR: In this article, a load-commutated inverter synchronous motor drive system employing a simple auxiliary commutation circuit for machine startup is analyzed, and results hybrid computer simulation are presented.
Abstract: A load-commutated inverter synchronous motor drive system employing a simple auxiliary commutation circuit for machine startup analyzed, and results hybrid computer simulation are presented. The commutation circuit employs a single commutation capacitor connected to the neutral of the machine and two auxiliary thyristors, which are used only during machine starting. A practical operating scheme is developed for the forced commutated inverter, which insures commutation over all load currents by actively allowing the commutation capacitor to charge to a voltage proportional to load, current. Results of key computer runs are given including inverter waveforms, transient waveforms during transition from forced to load commutation, as well as the effect of forced commutation and load commutation on pulsating torque. The forced-commutation circuit is used only for synchronous machine startup. However, due to its simplicity it also is an attractive alternative to be considered for other types of current-fed inverter ac drives.
45 citations