EPE Association: EPE 1991 - 18 - Session 2.7: INDUCTION MOTOR DRIVES

EPE 1991 - 18 - Session 2.7: INDUCTION MOTOR DRIVES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 18 - Session 2.7: INDUCTION MOTOR DRIVES

   [return to parent folder]

   MODELLING OF A NICKEL-CADMIUM-BATTERY AND SIMULATION OF AN INDUCTION MOTOR DRIVE WITII A NICKEL-CADMIUM-BATTERY AND A DC-LINK CAPACITOR
By Jochen Langheim; Friedhelm Schöpe [View]
[Download]

Abstract: An electric vehicle will be equipped with induction motors, PWM-converters and a Nickel-Cadmium battery. The induction motors have a low leakage factor and a large field weakening range. The PWM-converters operate at a high switching frequency. The use of induction motors leads to reactive currents in the battery which cause additional ohmic losses. A DC-link capacitor can reduce this effect. In order to estimate the influence of such a capacitor simulations have been carried out. This paper presents the modelling of the battery and the drive system as well as simulation results and measurement results.

   LOW-COST CONTROL STRATEGY FOR ELECTRICAL DRIVES
By K. Hofer [View]
[Download]

Abstract: Today, microprocessors play a dominating role in the control of electrical drives as the combination of micro electronics, power electronics and unconventional control strategies allows the design of innovative drive solutions. In contrast to the well-known control concepts which require sensors and analogous interfaces the presented control strategy is highly suitable for Low-Cost applications because all actual values are generated by observers (software). As there is no analogous signal processing in this digital control concept, there is less hardware for the realization of this and it is cheaper. This paper deals with the mathematical description of Low-Cost drive control using a dc-drive as an example. The results can be easily transformed to all ac-drives fed by commutationsless or self-commutated power converters.

   PREDICTING TORQUE PULSATIONS IN A SLIP ENERGY RECOVERY INDUCTION MOTOR DRIVE
By E. Akpinar; A. Ersak; P. Pillay [View]
[Download]

Abstract: The impedances in the induction motor (I/M) equivalent circuit provide a considerable amount of commutation impedance to the rectifier connected to wound-rotor terminals of the motor. This results in several tens of degrees of overlap angle in the rectifier. It has been reported that the overlap angle has a notable effect both upon the value of the average electromagnetic torque and prediction of torque neglecting the overlap is having an error of 15% [1]. This paper considers effects of overlap on the rectifier output voltage and also effects of the harmonics produced by the two converters present in the slip energy recovery system in calculating the electromagnetic torque of the machine. Pulsating torques arise from the interactions of all different harmonics.

   TIME-LIMITED TRANSITION BETWEEN TWO STATIONARY STATES FOR INDUCTION MOTORS WITH DEEP BAR COMPENSATION
By Freddie de Beer; J . Ben Klaassens; W. Deleroi [View]
[Download]

Abstract: A sudden uncontrolled change in the phase, amplitude or frequency of the stator voltage causes undesired pulsations in the torque of the machine. Field-oriented control strategy for induction motors is a method to control and improve this transient behavior. The paper shows an alternative means to control electro-magnetic transitions between a starting stationary state and an ending stationary state of the induction motor with a deep bar compensation. Only the measurement of the rotor speed processed by a relatively slow microprocessor is sufficient for the presented open-loop control strategy. Immediately after the transition the currents and torque are in their new steady state.

   STUDY OF A VARIABLE SPEED, DOUBLE FED INDUCTION MOTOR DRIVE SYSTEM WITH BOTH STATOR- AND ROTORVOLTAGES CONTROLABLE
By D. Lecocq; P. Lataire [View]
[Download]

Abstract: This paper deals with the control or a wound rotor induction machine, with both stator and rotor connected to a cycloconvertor. Applying field orientation, a variable speed drive is obtained where speed, flux, powerfactor and slip can be controlled independently even during transient operation. The steady state and transient performance of the proposed drive is demonstrated by computer simulation.

   THE OPERATION AND PERFORMANCE OF A HIDDEN LINK INDUCTION MOTOR DRIVE
By P. W. Lefley; G. M. Asher [View]
[Download]

Abstract: This paper describes the unusual operation of a Hidden Link Converter fed Cage Induction Motor Drive which can be driven from Zero through to 86 Hz excitation frequency whilst employing only naturally commutated converter grade thyristors. The experimental rig constructed to investigate the technical viability of the drive is described and some initial open-loop system results are given. Commutation phenomena are described and future aspects of the research programme, aimed at overcoming the inherent phase modulation of the motor currents, are discussed.

   INVERTER MOTOR WITH SINUSOIDAL STARTING CURRENTS - SOLUTIONS WITH 3 DC-LINKS
By G. Möhlenkamp [View]
[Download]

Abstract: Inverter motors use only simple line and machine commutated converters and have proved good performance for drives in the MW-range. They cause a high torque ripple, being disturbing only at low frequencies, and require additional commutation devices under heavy start-up conditions. The also very economic cycloconverters are only useful for machine frequencies up to 40% of line frequency. In this paper two circuits are described, whereby each system can be used at two operation modes: cycloconverter mode and inverter-motor mode. Each circuit operates like a cycloconverter at start-up and low frequencies of the motor, and as a current source inverter at high speeds. A soft and an abrupt switchover from one operating mode to the other without any transient is shown.

   STABILIZING METHODS AT HIGH FREQUENCIES FOR AN INDUCTION MOTOR DRIVEN BY A PWM INVERTER
By N. Mutoh; K. Sakai; A. Ueda [View]
[Download]

Abstract: New control methods are described which can suppress instability generated at high frequencies when an induction motor is driven by a PWM inverter. The methods are discussed according to two categories of motor driving systems: using closed loop control with current regulators, and using open-loop control with ony PWM controllers. In the former, the method prevents instability of the primary currents from occurring at high frequencies by compensating for gain reduction and phase-lag of current regulators while controlling amplitude and frequency of the carrier wave. In the latter, the method prevents oscillations of primary currents from occurring at high frequencies by generating PWM signals while controlling the sampling time of the PWM control so that the sampling phase can be synchronized with the instantaneous phase of the primary magnetic flux reference. Experiments confirm that both methods enable induction motors to be stably driven up to high frequencies such as 500Hz.

   ENERGY EFFICIENT SOLID-STATE INDUCTION MOTOR CONTROLLER
By G. Bhuvaneswari; V.V. Sastry [View]
[Download]

Abstract: A three phase voltage controller has been designed to save energy when the motor is lightly loaded. In this paper power-factor maximisation concept and the stator current minimisation technique have been used together to make the controller a hybrid between current minimisation and power factor maximisation schemes. This has been implemented in two different ways: (i) Repeating the optimisation of the stator current until the motor side power factor reaches a reasonably good value like 0.8 (lag); (ii) Adopting a P-I controller algorithm first to bring the power factor angle to a preset reference value and then minimise the stator current. The results obtained by these two approaches are discussed here.

   STANDSTILL TESTING OF PROPERTIES OF INDUCTION MOTORS FOR INVERTER CONTROL
By H. Weibull; T. Magnusson; J. Valis [View]
[Download]

Abstract: The paper suggests a simple yet versatile method for measurement of properties of induction motors in standstill by applying only a DC and/or a single-phase AC voltage to the motor windings. lnductances, resistances; additional losses; acoustic properties such as mechanical resonance frequencies of various motor parts and acoustic frequency characteristics can be determined for frequencies up to tens of kilohertz. The method is thus suitable for characterisation of induction motors for inverter operation. The electromagnetic-mechanical resonance frequencies of induction motors can also be easily determined.

   OSCILLATIONS IN INVERTER FED INDUCTION MOTOR DRIVES
By B. Peterson; J . Valis [View]
[Download]

Abstract: Severe oscillations in the range of 1 to 100 Hz have been encountered in inverter fed induction motor drive systems, especially where there are no external damping-loads such as fan drives. These oscillations may damage the drive system or generate noise. The reason for the oscillations have not been properly understood yet. A simple mechanical model is presented which gives physical insight into the reason for the oscillations.

   COMPARISON OF STARTING CONDITIONS OF INDUCTION MOTORS FED FROM AN INFINITE BUS AND CURRENT SOURCE INVERTOR USING FINITE ELEMENT CALCULATIONS
By R. Belmans; D. Verdyck; T.-B. Johansson; W. Geysen [View]
[Download]

Abstract: The paper discusses the comparison between the locked rotor behaviour of a squirrel cage induction motor when fed with qa variable stator frequency. The losses in the rotor are calculated for both infinite bus with sinusoidal voltage and block shape current from a Current Source lnverter (CSI). The behaviour is simulated using the finite element technique. For the simulation of the sinusoidal supply situation, a modified time harmonic solution is used. For the simulation of the CSI situation, a special method is developed accounting for saturation. The losses in the rotor by the induced currents are calculated from the vector potential solution. From the losses the torque is deduced. The torque results are experimentally verified.

   STABILITY ANALYSIS OF A CURRENT SOURCE INVERTER-INDUCTION MOTOR DRIVE SYSTEM WITH IP CONTROLLER
By M. Said Abd El-Motaleb; Hisham A. El-Khashab; Aziza M. Zaki [View]
[Download]

Abstract: A suggested linear sampled-data model of a current source-fed induction motor under vector control is investigated. taking into consideration the DC link current ripple, electromechanical dynamics and commutation phenomena. The proposed model is used for the stability analysis of the system when an integral plus proportional controller is considered. The eigenvalues of the plant transition matrix are examined for computing transient responses . Also the effect of commutation phenomena on stability is analyzed by comparing it with the results of the analysis in which only the fundamental component is considered.

   DYNAMIC PERFORMANCE OF AN INVERTER-FED INDUCTION MOTOR WITH THE VOLTAGE-CURRENT-PATTERN CONTROL FOR POWER SAVING
By Osamu Miyashita; Hideo Tomita; Shao Jun Zheng; Toshimasa Haneyoshi; Akeshi Maeda [View]
[Download]

Abstract: Dynamic performance analysis of an inverter-fed induction motor driven by the voltage-current pattern (V-I pattern) control for power saving is presented. The V-I pattern control is a control method for improving motor efficiency. The method can be applied to an induction motor having a changeable or on-and-off load, and it saves energy when the motor runs in moderate and light load condition. To create a more sophisticated inverter-motor system it is necessary to investigate the dynamic performance of the motor under the V-I pattern control both theoretically and experimentally. In this paper, we discuss the motor performance using a transient equivalent circuit with consideration of time-harmonics which affect iron loss and deep-bar-rotor copper loss, and the simulation is carried out by using the spiral-vector method. The simulation and experimental results show that the proposed efficiency-improving motor driving system is useful in power-saving applications.

   FOUR QUADRANT MICROPROCESSOR CONTROLLED CURRENT SOURCE INVERTER-FED INDUCTION MOTOR DRIVE FOR SPECIAL PURPOSE
By M. Hunyár; T. Molnár; K. Veszprémi [View]
[Download]

Abstract: When the dynamic requirements are not too high, and the good efficiency is important, instead of the complicated field oriented control a more simple control method is suggested. The original idea of slip frequency control is improved, taking into consideration the changing of the resistance. Direct open-control of firing during transient conditions is used to improve dynamic behaviour. Rules to select the proper sampling rate for speed control is suggested. The control is fully realized by a microcomputer. The most interesting operating conditions (starting, breaking, speed reversal) were examined and recorded. Recorded time functions and Park-vector loci are presented. The experimental results indicate a stable operation and a good dynamic response.

   THE STEADY STATE AND TRANSIENT PERFORMANCES OF A DOUBLE FED ASYNCHRONOUS MACHINE (DFAM)
By Ioan Felician Soran [View]
[Download]

Abstract: The paper presents the performances of a DFAM whose stator is connected to the industrial grid and rotor supplied by a three phase voltage source which keeps constant the ratio r = u2 /f2. The steady state characteristics and the dynamic behaviour are investigated to obtain the guidelines for the various possibilities of control. The equations of DFAM are written in terms of space vectors. The dynamic behaviour is investigated by the numerical integration of the equations. The slip-angle characteristic is considered very important for obtaining the domain of slips where work at constant torque is possible. The dynamic performances are poor when the voltage source has no automatic control. The balance of the reactive powers at various values of the ratio r leads to the idea of a control strategy at unity power factor to the industrial grid.

   STARTING DEVICE FOR A SINGLE PHASE INDUCTION MOTOR FED BY A.C. REGULATORS
By I. Rasoanarivo; G. Manesse [View]
[Download]

Abstract: This paper proposes an electronic solution for the moving off of usual single phase induction motors fed by the industrial network. This process enables the elimination of passive components (capacitor) generally used in the majority of equipments, and the mechanical centrifugal contactor. The selected principle consists in feeding the two stator phases of the motor accross two thyristor A.C. regulators. Then, the control device of the four thyristors triggers simultaneously performs a frequency division and the phase shift of the statoric phases currents. The aim of theorical study is to show the behavour system possibilities. On theorical level, control sequences are generated by a temporal phasor owing Petri nets properties: the two A.C. regulators are controlled by one generalized graph. This last graph decides the phase shift between the two indor coils. The two rotation senses are possible with the same. Finally, an experimental curves of currents and speed which are cornpared with simulation results.

   A LOW COST VARIABLE SPEED INDUCTION MOTOR DRIVE WITH IMPROVED STATIC AND DYNAMIC PROPERTIES
By Vladan Vuckovic; Slobodan Vukosavic [View]
[Download]

Abstract: In many applications of converter-fed induction motor drives the DC-link current is the only variable measured for protection and control purposes. In this paper, control structure for accurate regulation of the motor speed and flux is proposed, relying on the DC-link current sensor only. Proposed controller results in excellent static accuracy in the wide speed region and gives well damped dynamic behavior with acceptable response time. Paper presents analytical evaluation of the speed and flux controller and includes verification results obtained through the computer simulation of the drive.

   TORQUE PULSATIONS IN MICROPROCESSOR CONTROLLED ASYNCHRONOUS MOTORS
By C. Attaianese; M. Scarano [View]
[Download]

Abstract: The use of microprocessors in the control line of an electrical machine implies the digitalization of the input and output quantities, which are given and processed in sampled form. This gives rise to deviations of the motor-output quantities from the reference ones imposed by the control and feeding strategies. The paper deals with the torque pulsations evaluation of digitally controlled asynchronous motors. In particular, reference is made to asynchronous motors supplied by PWM-VSI inverter with current control loop. It is shown that in steady-state operating conditions an easy analytical law links the maximum torque ripple with the sampling frequency and the motor parameters. This law can be used to obtain a proper design of the motor control line.

   IMPROVED STARTING TORQUE FOR INDUCTION MOTORS ENERGIZED FROM A SINGLE PHASE MAINS
By Alex P. M. Van den Bossche; Jan A. A. Melkebeek [View]
[Download]

Abstract: Solid state soft starters based on triacs or SCR's are often used to lower the starting current of three phase motors. Consequently, also the starting torque will decrease. However, for single phase motors, more particulary permanent-split capacitor motors, often an increased starting torque is desired. In this paper a quite surprising solution is presented. A triac in series with the capacitor can improve the starting torque considerably. The circuit turns out to be competitive with a two value capacitor circuit. The same principle can also be applied to three phase motors in steinmetz configuration, yielding similar improvements.

   TORQUE RIPPLES ANALYSIS IN INDUCTION MOTOR DRIVEN BY CURRENT SOURCE INVERTER
By K. Lee [View]
[Download]

Abstract: A new method that estimates the torque fluctuations in induction motor driven by current source inverter under steady-state condition is presented and that uses the phasor diagram from the modified single phase equivalent circuit. This new method is also applied to evaluate the PWM and programmed DC link modulation techniques for reducing the torque ripples. The simplified calculations are compared with the exact digital solutions from machine d-q eauation. It is noted that the torque ripples in induction motor driven by current source inverter are dependent upon the load condition unlike voltage source inverter.

EPE 1991 - 18 - Session 2.7: INDUCTION MOTOR DRIVES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 18 - Session 2.7: INDUCTION MOTOR DRIVES
	[return to parent folder]

	MODELLING OF A NICKEL-CADMIUM-BATTERY AND SIMULATION OF AN INDUCTION MOTOR DRIVE WITII A NICKEL-CADMIUM-BATTERY AND A DC-LINK CAPACITOR By Jochen Langheim; Friedhelm Schöpe	[View] [Download]
Abstract: An electric vehicle will be equipped with induction motors, PWM-converters and a Nickel-Cadmium battery. The induction motors have a low leakage factor and a large field weakening range. The PWM-converters operate at a high switching frequency. The use of induction motors leads to reactive currents in the battery which cause additional ohmic losses. A DC-link capacitor can reduce this effect. In order to estimate the influence of such a capacitor simulations have been carried out. This paper presents the modelling of the battery and the drive system as well as simulation results and measurement results.

	LOW-COST CONTROL STRATEGY FOR ELECTRICAL DRIVES By K. Hofer	[View] [Download]
Abstract: Today, microprocessors play a dominating role in the control of electrical drives as the combination of micro electronics, power electronics and unconventional control strategies allows the design of innovative drive solutions. In contrast to the well-known control concepts which require sensors and analogous interfaces the presented control strategy is highly suitable for Low-Cost applications because all actual values are generated by observers (software). As there is no analogous signal processing in this digital control concept, there is less hardware for the realization of this and it is cheaper. This paper deals with the mathematical description of Low-Cost drive control using a dc-drive as an example. The results can be easily transformed to all ac-drives fed by commutationsless or self-commutated power converters.

	PREDICTING TORQUE PULSATIONS IN A SLIP ENERGY RECOVERY INDUCTION MOTOR DRIVE By E. Akpinar; A. Ersak; P. Pillay	[View] [Download]
Abstract: The impedances in the induction motor (I/M) equivalent circuit provide a considerable amount of commutation impedance to the rectifier connected to wound-rotor terminals of the motor. This results in several tens of degrees of overlap angle in the rectifier. It has been reported that the overlap angle has a notable effect both upon the value of the average electromagnetic torque and prediction of torque neglecting the overlap is having an error of 15% [1]. This paper considers effects of overlap on the rectifier output voltage and also effects of the harmonics produced by the two converters present in the slip energy recovery system in calculating the electromagnetic torque of the machine. Pulsating torques arise from the interactions of all different harmonics.

	TIME-LIMITED TRANSITION BETWEEN TWO STATIONARY STATES FOR INDUCTION MOTORS WITH DEEP BAR COMPENSATION By Freddie de Beer; J . Ben Klaassens; W. Deleroi	[View] [Download]
Abstract: A sudden uncontrolled change in the phase, amplitude or frequency of the stator voltage causes undesired pulsations in the torque of the machine. Field-oriented control strategy for induction motors is a method to control and improve this transient behavior. The paper shows an alternative means to control electro-magnetic transitions between a starting stationary state and an ending stationary state of the induction motor with a deep bar compensation. Only the measurement of the rotor speed processed by a relatively slow microprocessor is sufficient for the presented open-loop control strategy. Immediately after the transition the currents and torque are in their new steady state.

	STUDY OF A VARIABLE SPEED, DOUBLE FED INDUCTION MOTOR DRIVE SYSTEM WITH BOTH STATOR- AND ROTORVOLTAGES CONTROLABLE By D. Lecocq; P. Lataire	[View] [Download]
Abstract: This paper deals with the control or a wound rotor induction machine, with both stator and rotor connected to a cycloconvertor. Applying field orientation, a variable speed drive is obtained where speed, flux, powerfactor and slip can be controlled independently even during transient operation. The steady state and transient performance of the proposed drive is demonstrated by computer simulation.

	THE OPERATION AND PERFORMANCE OF A HIDDEN LINK INDUCTION MOTOR DRIVE By P. W. Lefley; G. M. Asher	[View] [Download]
Abstract: This paper describes the unusual operation of a Hidden Link Converter fed Cage Induction Motor Drive which can be driven from Zero through to 86 Hz excitation frequency whilst employing only naturally commutated converter grade thyristors. The experimental rig constructed to investigate the technical viability of the drive is described and some initial open-loop system results are given. Commutation phenomena are described and future aspects of the research programme, aimed at overcoming the inherent phase modulation of the motor currents, are discussed.

	INVERTER MOTOR WITH SINUSOIDAL STARTING CURRENTS - SOLUTIONS WITH 3 DC-LINKS By G. Möhlenkamp	[View] [Download]
Abstract: Inverter motors use only simple line and machine commutated converters and have proved good performance for drives in the MW-range. They cause a high torque ripple, being disturbing only at low frequencies, and require additional commutation devices under heavy start-up conditions. The also very economic cycloconverters are only useful for machine frequencies up to 40% of line frequency. In this paper two circuits are described, whereby each system can be used at two operation modes: cycloconverter mode and inverter-motor mode. Each circuit operates like a cycloconverter at start-up and low frequencies of the motor, and as a current source inverter at high speeds. A soft and an abrupt switchover from one operating mode to the other without any transient is shown.

	STABILIZING METHODS AT HIGH FREQUENCIES FOR AN INDUCTION MOTOR DRIVEN BY A PWM INVERTER By N. Mutoh; K. Sakai; A. Ueda	[View] [Download]
Abstract: New control methods are described which can suppress instability generated at high frequencies when an induction motor is driven by a PWM inverter. The methods are discussed according to two categories of motor driving systems: using closed loop control with current regulators, and using open-loop control with ony PWM controllers. In the former, the method prevents instability of the primary currents from occurring at high frequencies by compensating for gain reduction and phase-lag of current regulators while controlling amplitude and frequency of the carrier wave. In the latter, the method prevents oscillations of primary currents from occurring at high frequencies by generating PWM signals while controlling the sampling time of the PWM control so that the sampling phase can be synchronized with the instantaneous phase of the primary magnetic flux reference. Experiments confirm that both methods enable induction motors to be stably driven up to high frequencies such as 500Hz.

	ENERGY EFFICIENT SOLID-STATE INDUCTION MOTOR CONTROLLER By G. Bhuvaneswari; V.V. Sastry	[View] [Download]
Abstract: A three phase voltage controller has been designed to save energy when the motor is lightly loaded. In this paper power-factor maximisation concept and the stator current minimisation technique have been used together to make the controller a hybrid between current minimisation and power factor maximisation schemes. This has been implemented in two different ways: (i) Repeating the optimisation of the stator current until the motor side power factor reaches a reasonably good value like 0.8 (lag); (ii) Adopting a P-I controller algorithm first to bring the power factor angle to a preset reference value and then minimise the stator current. The results obtained by these two approaches are discussed here.

	STANDSTILL TESTING OF PROPERTIES OF INDUCTION MOTORS FOR INVERTER CONTROL By H. Weibull; T. Magnusson; J. Valis	[View] [Download]
Abstract: The paper suggests a simple yet versatile method for measurement of properties of induction motors in standstill by applying only a DC and/or a single-phase AC voltage to the motor windings. lnductances, resistances; additional losses; acoustic properties such as mechanical resonance frequencies of various motor parts and acoustic frequency characteristics can be determined for frequencies up to tens of kilohertz. The method is thus suitable for characterisation of induction motors for inverter operation. The electromagnetic-mechanical resonance frequencies of induction motors can also be easily determined.

	OSCILLATIONS IN INVERTER FED INDUCTION MOTOR DRIVES By B. Peterson; J . Valis	[View] [Download]
Abstract: Severe oscillations in the range of 1 to 100 Hz have been encountered in inverter fed induction motor drive systems, especially where there are no external damping-loads such as fan drives. These oscillations may damage the drive system or generate noise. The reason for the oscillations have not been properly understood yet. A simple mechanical model is presented which gives physical insight into the reason for the oscillations.

	COMPARISON OF STARTING CONDITIONS OF INDUCTION MOTORS FED FROM AN INFINITE BUS AND CURRENT SOURCE INVERTOR USING FINITE ELEMENT CALCULATIONS By R. Belmans; D. Verdyck; T.-B. Johansson; W. Geysen	[View] [Download]
Abstract: The paper discusses the comparison between the locked rotor behaviour of a squirrel cage induction motor when fed with qa variable stator frequency. The losses in the rotor are calculated for both infinite bus with sinusoidal voltage and block shape current from a Current Source lnverter (CSI). The behaviour is simulated using the finite element technique. For the simulation of the sinusoidal supply situation, a modified time harmonic solution is used. For the simulation of the CSI situation, a special method is developed accounting for saturation. The losses in the rotor by the induced currents are calculated from the vector potential solution. From the losses the torque is deduced. The torque results are experimentally verified.

	STABILITY ANALYSIS OF A CURRENT SOURCE INVERTER-INDUCTION MOTOR DRIVE SYSTEM WITH IP CONTROLLER By M. Said Abd El-Motaleb; Hisham A. El-Khashab; Aziza M. Zaki	[View] [Download]
Abstract: A suggested linear sampled-data model of a current source-fed induction motor under vector control is investigated. taking into consideration the DC link current ripple, electromechanical dynamics and commutation phenomena. The proposed model is used for the stability analysis of the system when an integral plus proportional controller is considered. The eigenvalues of the plant transition matrix are examined for computing transient responses . Also the effect of commutation phenomena on stability is analyzed by comparing it with the results of the analysis in which only the fundamental component is considered.

	DYNAMIC PERFORMANCE OF AN INVERTER-FED INDUCTION MOTOR WITH THE VOLTAGE-CURRENT-PATTERN CONTROL FOR POWER SAVING By Osamu Miyashita; Hideo Tomita; Shao Jun Zheng; Toshimasa Haneyoshi; Akeshi Maeda	[View] [Download]
Abstract: Dynamic performance analysis of an inverter-fed induction motor driven by the voltage-current pattern (V-I pattern) control for power saving is presented. The V-I pattern control is a control method for improving motor efficiency. The method can be applied to an induction motor having a changeable or on-and-off load, and it saves energy when the motor runs in moderate and light load condition. To create a more sophisticated inverter-motor system it is necessary to investigate the dynamic performance of the motor under the V-I pattern control both theoretically and experimentally. In this paper, we discuss the motor performance using a transient equivalent circuit with consideration of time-harmonics which affect iron loss and deep-bar-rotor copper loss, and the simulation is carried out by using the spiral-vector method. The simulation and experimental results show that the proposed efficiency-improving motor driving system is useful in power-saving applications.

	FOUR QUADRANT MICROPROCESSOR CONTROLLED CURRENT SOURCE INVERTER-FED INDUCTION MOTOR DRIVE FOR SPECIAL PURPOSE By M. Hunyár; T. Molnár; K. Veszprémi	[View] [Download]
Abstract: When the dynamic requirements are not too high, and the good efficiency is important, instead of the complicated field oriented control a more simple control method is suggested. The original idea of slip frequency control is improved, taking into consideration the changing of the resistance. Direct open-control of firing during transient conditions is used to improve dynamic behaviour. Rules to select the proper sampling rate for speed control is suggested. The control is fully realized by a microcomputer. The most interesting operating conditions (starting, breaking, speed reversal) were examined and recorded. Recorded time functions and Park-vector loci are presented. The experimental results indicate a stable operation and a good dynamic response.

	THE STEADY STATE AND TRANSIENT PERFORMANCES OF A DOUBLE FED ASYNCHRONOUS MACHINE (DFAM) By Ioan Felician Soran	[View] [Download]
Abstract: The paper presents the performances of a DFAM whose stator is connected to the industrial grid and rotor supplied by a three phase voltage source which keeps constant the ratio r = u2 /f2. The steady state characteristics and the dynamic behaviour are investigated to obtain the guidelines for the various possibilities of control. The equations of DFAM are written in terms of space vectors. The dynamic behaviour is investigated by the numerical integration of the equations. The slip-angle characteristic is considered very important for obtaining the domain of slips where work at constant torque is possible. The dynamic performances are poor when the voltage source has no automatic control. The balance of the reactive powers at various values of the ratio r leads to the idea of a control strategy at unity power factor to the industrial grid.

	STARTING DEVICE FOR A SINGLE PHASE INDUCTION MOTOR FED BY A.C. REGULATORS By I. Rasoanarivo; G. Manesse	[View] [Download]
Abstract: This paper proposes an electronic solution for the moving off of usual single phase induction motors fed by the industrial network. This process enables the elimination of passive components (capacitor) generally used in the majority of equipments, and the mechanical centrifugal contactor. The selected principle consists in feeding the two stator phases of the motor accross two thyristor A.C. regulators. Then, the control device of the four thyristors triggers simultaneously performs a frequency division and the phase shift of the statoric phases currents. The aim of theorical study is to show the behavour system possibilities. On theorical level, control sequences are generated by a temporal phasor owing Petri nets properties: the two A.C. regulators are controlled by one generalized graph. This last graph decides the phase shift between the two indor coils. The two rotation senses are possible with the same. Finally, an experimental curves of currents and speed which are cornpared with simulation results.

	A LOW COST VARIABLE SPEED INDUCTION MOTOR DRIVE WITH IMPROVED STATIC AND DYNAMIC PROPERTIES By Vladan Vuckovic; Slobodan Vukosavic	[View] [Download]
Abstract: In many applications of converter-fed induction motor drives the DC-link current is the only variable measured for protection and control purposes. In this paper, control structure for accurate regulation of the motor speed and flux is proposed, relying on the DC-link current sensor only. Proposed controller results in excellent static accuracy in the wide speed region and gives well damped dynamic behavior with acceptable response time. Paper presents analytical evaluation of the speed and flux controller and includes verification results obtained through the computer simulation of the drive.

	TORQUE PULSATIONS IN MICROPROCESSOR CONTROLLED ASYNCHRONOUS MOTORS By C. Attaianese; M. Scarano	[View] [Download]
Abstract: The use of microprocessors in the control line of an electrical machine implies the digitalization of the input and output quantities, which are given and processed in sampled form. This gives rise to deviations of the motor-output quantities from the reference ones imposed by the control and feeding strategies. The paper deals with the torque pulsations evaluation of digitally controlled asynchronous motors. In particular, reference is made to asynchronous motors supplied by PWM-VSI inverter with current control loop. It is shown that in steady-state operating conditions an easy analytical law links the maximum torque ripple with the sampling frequency and the motor parameters. This law can be used to obtain a proper design of the motor control line.

	IMPROVED STARTING TORQUE FOR INDUCTION MOTORS ENERGIZED FROM A SINGLE PHASE MAINS By Alex P. M. Van den Bossche; Jan A. A. Melkebeek	[View] [Download]
Abstract: Solid state soft starters based on triacs or SCR's are often used to lower the starting current of three phase motors. Consequently, also the starting torque will decrease. However, for single phase motors, more particulary permanent-split capacitor motors, often an increased starting torque is desired. In this paper a quite surprising solution is presented. A triac in series with the capacitor can improve the starting torque considerably. The circuit turns out to be competitive with a two value capacitor circuit. The same principle can also be applied to three phase motors in steinmetz configuration, yielding similar improvements.

	TORQUE RIPPLES ANALYSIS IN INDUCTION MOTOR DRIVEN BY CURRENT SOURCE INVERTER By K. Lee	[View] [Download]
Abstract: A new method that estimates the torque fluctuations in induction motor driven by current source inverter under steady-state condition is presented and that uses the phasor diagram from the modified single phase equivalent circuit. This new method is also applied to evaluate the PWM and programmed DC link modulation techniques for reducing the torque ripples. The simplified calculations are compared with the exact digital solutions from machine d-q eauation. It is noted that the torque ripples in induction motor driven by current source inverter are dependent upon the load condition unlike voltage source inverter.