EPE Association: EPE 1993 - 33 - Dialogue Session DS1.9: DRIVES: IDENTIFICATION, FIELD ORIENTATION AND CYCLO CONVERTERS

EPE 1993 - 33 - Dialogue Session DS1.9: DRIVES: IDENTIFICATION, FIELD ORIENTATION AND CYCLO CONVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 33 - Dialogue Session DS1.9: DRIVES: IDENTIFICATION, FIELD ORIENTATION AND CYCLO CONVERTERS

   [return to parent folder]

   THE EXPERIMENTAL INVESTIGATION OF ROTOR TIME CONSTANT IDENTIFICATION FOR VECTOR CONTROLLED INDUCTION MOTOR DRIVES DURING TRANSIENT OPERATING CONDITIONS
By M. Sumner; G. M. Asher; R. Pena [View]
[Download]

Abstract: For the indirect vector controlled induction motor drive employing the scheme based on rotor position measurement and inner current loops, the rotor time constant (f,) is the most influential time varying parameter. Detuning of T, between the controller and the actual machine leads to suboptimal torque response and inefficient operation. Furthermore the operation of the drive in the field weakening region deteriorates as the voltage ceiling of the inverter prevents correct current control if detuning occurs. In this study an extension of the Reactive Power ldentification Scheme [1] is presented and it is shown that the scheme can track the rotor time constant during both changing torque and flux conditions. The scheme is used in conjunction with a rotor flux orientated controller and simulation studies show that the method follows T, correctly under all operating conditions with a good accuracy. The experimental implementation of the procedure for field weakening conditions is presented.

   ADAPTIVE DECOUPLING CIRCUIT FOR UNIVERSAL FIELD ORIENTED CONTROLLER OPERATING IN THE AIRGAP FLUX REFERENCE FRAME
By E. Levi [View]
[Download]

Abstract: The paper discusses modifications of the decoupling circuit of a universal field oriented (UFO) controller which operates with orientation along airgap flux, that are necessary if the decoupler is to provide self-adaptive feature with respect to main flux saturation in the induction machine. It is shown that such an adaptive decoupling circuit can easily be derived. It asks for three nonlinear functional dependencies and provides full adaptation to instantaneous main flux saturation level in the machine. Verification is provided by simulation of a current-fed indirect vector controlled induction machine operating in the torque mode. The circuit enables very good matching between commanded and actual flux and torque values for any degree of the flux command variation. Possible simplifications of the full adaptive decoupling circuit are discussed as well and assessed by simulation. In particular, three different simplified structures that ask for reduced number of nonlinear functions, are discussed. It is shown that even the simplest structure where just one nonlinearity is retained provides superior responses compared to constant parameter decoupling circuit .

   A NEW DIRECT ROTOR FIELD ORIENTED SCHEME, USING THE THIRD HARMONIC COMPONENT OF THE AIR GAP FLUX
By D. O. Kisch; N. Galan [View]
[Download]

Abstract: The paper presents a new direct rotor field oriented scheme for induction motor, based on determination of the position and amplitude of the air gap flux, from the third harmonic component of the stator voltage. This field control utilizes spatial saturation harmonic components rotating at synchronous frequency that are generated in the air gap flux when the induction motor is in a saturated condition. This method is used when the induçtion machine is wye connected, because the sum of the three phase voltages results in a signal dominated by the third harmonic component. The scheme uses a minimum number of sensors. The controller eliminates the flux sensing coils placed into the air gap on the wedges of the stator slots (or Hall elements in the air gap). This direct method of the flux estimation, in comparison with other direct or indirect methods, has the quality to be insensible to changes in the stator or rotor parameter's values. Simulated and experimental results showing the nature of the third harmonic voltage and the responses of the oriented scheme are presented.

   ROTOR FLUX ORIENTED TORQUE-CONTROL OF INDUCTION MACHINES BASED ON STATOR FLUX VECTOR CONTROL
By D. Casadei; G. Grandi; G. Serra [View]
[Download]

Abstract: This paper describes a speed sensorless rotor flux oriented torque-control of induction machines which utilises stator flux components as control variables. Combining the advantages of rotor flux orientation and stator flux space vector control leads to high performance drives using a simple control scheme. This scheme is affected by total leakage inductance variations which determine detuned operation. A method is presented that provides the possibility to estimate the total leakage inductance besides the identification of stator self inductance. The effectiveness of the proposed system is verified by computer simulation and experimental tests.

   μ-ANALYSIS APPLIED TO FIELD ORIENTED CONTROL OF INDUCTION MOTOR
By J.L. Thomas [View]
[Download]

Abstract: This paper presents an alternative method, the "μ-Analysis", for studying the robustness of the well-known field-oriented control of induction machine. The method, based on the structured singular value analysis, is used to analyse the robust stability and robust performance of closed-loop systems, here the motor with its associated control law, against several simultaneous plant uncertainties. The purpose of this paper is to give the worst-case effects of motor parameter variations on the stability and performance of the field-oriented drive structure. Furthermore, the author shows that the unmodeled drive dynamics can be introduced as unstructured uncertainties by using frequency-weighting transfer functions. This paper develops the nominal transfer function matrix of the entire indirect vector control scheme and gives the uncertainty block structure to perform the linear fractional transformation commonly defined in "μ-Analysis" theory. Simulation results are discussed and demonstrate the effectiveness of the proposed method applied to an industrial AC-drive example.

   STATOR PARAMETERS INFLUENCE ON THE FIELD-ORIENTED CONTROL TUNING
By L. Loron [View]
[Download]

Abstract: High performance drives can be achieved by applying indirect field-oriented control to induction motors. To perform the field orientation and to obtain a fast and accurate torque control, a suitable model of the motor must be employed. A parametric model with only four electrical parameters is presented. This model is optimal for motor identification and controller implementation. Only two parameters of the model (the rotor parameters) are involved in the indirect field-oriented control when the motor is fed by a current regulated inverter. Several schemes can be employed to estimate these parameters; an extended Kalman filter is proposed because of its advantages and performance. However, the Kalman filter, like most motor identification schemes uses stator voltage and current measurements and relies on the stator parameters values, so errors in the stator parameters can alter the rotor parameter estimations. The stator parameters influence (during the estimation of the rotor parameters) is analyzed for steady-state and transient operating conditions.

   APPLICATION OF THE EXTENDED KALMAN FILTER TO PARAMETERS ESTIMATION OF INDUCTION MOTORS
By L. Loron; G. Laliberté [View]
[Download]

Abstract: In this paper the extended Kalman filter theory is applied to the electrical parameter estimation of induction motors. This filter only uses machine quantities, which can be easily measured: the stator voltages and currents, and the rotor speed. The model of the induction motor is characterized by four parameters, which have to be simultaneously estimated. The filter settings are presented and discussed. These settings and the initial parameters set are deduced directly from the motor indicated characteristics. Experimental results show that the Kalman filter can perform a fast identification of the motor model. Then the model accuracy is evaluated by comparison of estimated and measured torque. Today the extended Kalman filter can be used as a parameter estimator for the tuning of the indirect field-oriented controller. Soon, it will also allow adaptive direct field-oriented control.

   SIMPLIFICATIONS ON FIELD ORIENTED CONTROL FOR LOW POWER VOLTAGE-SOURCE INDUCTION MOTOR DRIVES
By J. P. Palma; J. G. Dente; F. J. Carvalhal [View]
[Download]

Abstract: The paper presents the last results of a research on the simplification of field orientation control methods for induction motor drives in stator, rotor, and air gap flux coordinates and using a PWM voltage-source inverter. The application of the input-output linearization method yields sophisticated control laws. Some simplification steps are taken next in order to achieve control procedures of decreasing complexity, specially devised for economy in low power drives. Steady state and dynamic performance are analytically studied, as well as robustness to the variation of parameters. The comparison with other related methods shows a progress in this field. Experimental results of speed and position control are reported from a prototype with a single eight-bit microcontroller, and confirm the expected performance.

   PARAMETER IDENTIFICATION OF AN INVERTER-FED INDUCTION MOTOR AT STANDSTILL WITH A CORRELATION METHOD
By A. Bünte; H. Grotstollen [View]
[Download]

Abstract: Two methods to identify the electrical parameters and the magnetization curve of a voltage source inverter-fed induction motor (IM) at standstill will be presented. A special advantage of these methods is that the differences between the reference voltage values and the real phase voltage values caused by the unknown switching times of the PWM-inverter will be completely suppressed. Therefore a measurement of the phase voltage is not necessary and the parameters of the induction motor can be estimated with a high accuracy. Thus, no addltional hardware is necessary and therefore this identification rnethod is a good solution for use in commercial self-commissioning drives.

   IDENTIFICATION OF THE SATURATED MUTUAL INDUCTANCE OF AN ASYNCHRONOUS MOTOR AT STANDSTILL BY RECURSIVE LEAST SQUARES ALGORITHM
By M. Ruff; H. Grotstollen [View]
[Download]

Abstract: A method is proposed which estimates the nonlinear function of the mutual inductance of an asynchronous motor. With the obtained function it is possible to calculate the control parameters, e.g. for a field oriented control. An important advantage of this method is that the identification of the mutual inductance can be taken automatically at standstill without locking the rotor mechanically. Therefore, the proposed method can be used for self commissioning of an induction motor drive. Simulation results are verified by a practical test using a squirrel cage motor.

   THE VECTOR CONTROLLED ASYNCHRONOUS ACTUATOR AND ITS USING POSSIBILITIES FOR EMBARKED APPLICATIONS
By J. P. Vilain; E. Milent [View]
[Download]

Abstract: The vector-control awards to the induction motor a precision and qualities comparable with those of DC or brushless machines. For embarked applications, the shortcoming that appears in the usual proceedings is the necessity of maintaining a constant magnetic flux, therefore creating a permanent heat dissipation and consuming continuously energy from the supply. The aim of this study is to conciliate the high dynamical performances offered by the vector-control with the necessity of being sparing of embarked energy. A novel vector strategy is suggested, which allows to master the torque, to increase the efficiency and to nullify the consumption of energy while the motor is not being requested. The performances are illustrated by an orientation servo-control of the rear wheels for a four directional wheeled vehicle. The definition, simulation, and experimentation results, in steady and dynamical state, are presented. The concordance between simulation and results ratify the suggested strategies. Even for embarked applications, the induction motor, well-known for robustness, very cheap manufacturing and quasi-nonexistent maintenance, competes with DC or brushless machines.

   IMPROVED TORQUE AND FLUX VECTOR CONTROL OF PWM INVERTER-FED INDUCTION MOTOR DRIVE
By M. P. Kazmierkowski; A. Kasprowicz [View]
[Download]

Abstract: In the paper a direct torque and stator flux vector control system is presented. The principle of this method was proposed by Takahashi and Noguchi in 1985. In contrast to the field oriented control, no coordinate transformation and current control loop is required. In practical application, however, problems occur with start and operation at zero speed region. This paper shows how by introducing an additional carrier signal to the torque controller input, the robust start and improved operation at low speed region can be achieved. The simulation and experimental results which illustrate the performances of the system are presented. Also, the nomogram for controller design and comparison with most popular current type of indirect field oriented control are presented.

   COMPUTER SIMULATION OF A CYCLOCONVERTER DRIVE AND DEVELOPMENT OF A FULL DIGITAL FIELD ORIENTED CONTROL
By E. Chiesa; A. Monti; M. Matuonto [View]
[Download]

Abstract: The paper reports the results of a research in the simulation and control fields, for the analysis of the operation of cycloconverter drives and the design of a new advanced digital control for such equipments. It describes in detail a simulation tool realised in C language to study power and control problems arising when using a cycloconverter to feed an AC motor. The power section is represented by means of a new model that allows easy adaptation to various circuit structures in steady state, transient and fault conditions. lt also allows immediate calculation of electrical parameters sizing and cost of the components. Conceming the control section, the simulator allows the analysis of hardware and software interferences; a discrete-time model is used so that the same C language routines are valid and portable on the real system. As a result of this research, Ansaldo Industria, in its Milan research centre, is on the way to test the first prototype of a 150 kW drive, based on a full digital controlled six pulse no-circulating current cycloconverter supplying an induction motor with Field Oriented Control.

   A SINGLE PHASE INPUT CYCLOCONVERTER DRIVING A THREE PHASE MOTOR
By J. Zhang; G. P. Hunter; V. S. Ramsden [View]
[Download]

Abstract: The paper presents a 1-phase to 3-phase cycloconverter suitable for driving an induction motor. The input of the cycloconverter is a single phase supply of 240V, 50Hz, and its output is a 3-phase supply with variable voltage and variable frequency (VVVF) up to 25Hz. Using a double integral control technique, a 1-ph to 3-ph modulation method is proposed so the motor flux follows a sinusoidal reference. Only six naturally commutated triacs are used in the power circuit, so the resulting cycloconverter-motor drive is cheap, compact and efficient. Software in C has been written for both simulation and real time control. The simulation is used to predict the performance of the cycloconverter and induction motor.

   A NOVEL CYCLOCONVERTER BASED ON MICROPROCESSOR DIGITAL CONTROL
By S. Hexu; Z. Xiaojie; C. Yan; L. Zongfu [View]
[Download]

Abstract: In view of the relative advantage of using a current-source converter for many high-performance drives, a novel cycloconverter that is composed of double H bridge converters has been developed as a three-phase sinusoidal current source of adjustable frequency. The power main circuit contains 20 thyristors and current control for two-phase H bridge converter are used to generate symmetrical three-phase currents. In this paper, we present the power main circuit, the operation pattern and discuss a microprocessor-based digital control cycloconverter (DCC) system that ensures high quality output. Among other aspects, the digital system facilitates stepping sinusoidal current control for the total distortion factor improvement, the method of current zero crossing, discrete compensation for feedback control, and online identification of the load parameter. The macromodel of thyristor for analog power circuit simulation using PSPICE has been devoloped. The novel cycloconverter bas been experimentalized on R-L load. The control strategies are elaborated upon, and simulation and experimental results are presented.

EPE 1993 - 33 - Dialogue Session DS1.9: DRIVES: IDENTIFICATION, FIELD ORIENTATION AND CYCLO CONVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 33 - Dialogue Session DS1.9: DRIVES: IDENTIFICATION, FIELD ORIENTATION AND CYCLO CONVERTERS
	[return to parent folder]

	THE EXPERIMENTAL INVESTIGATION OF ROTOR TIME CONSTANT IDENTIFICATION FOR VECTOR CONTROLLED INDUCTION MOTOR DRIVES DURING TRANSIENT OPERATING CONDITIONS By M. Sumner; G. M. Asher; R. Pena	[View] [Download]
Abstract: For the indirect vector controlled induction motor drive employing the scheme based on rotor position measurement and inner current loops, the rotor time constant (f,) is the most influential time varying parameter. Detuning of T, between the controller and the actual machine leads to suboptimal torque response and inefficient operation. Furthermore the operation of the drive in the field weakening region deteriorates as the voltage ceiling of the inverter prevents correct current control if detuning occurs. In this study an extension of the Reactive Power ldentification Scheme [1] is presented and it is shown that the scheme can track the rotor time constant during both changing torque and flux conditions. The scheme is used in conjunction with a rotor flux orientated controller and simulation studies show that the method follows T, correctly under all operating conditions with a good accuracy. The experimental implementation of the procedure for field weakening conditions is presented.

	ADAPTIVE DECOUPLING CIRCUIT FOR UNIVERSAL FIELD ORIENTED CONTROLLER OPERATING IN THE AIRGAP FLUX REFERENCE FRAME By E. Levi	[View] [Download]
Abstract: The paper discusses modifications of the decoupling circuit of a universal field oriented (UFO) controller which operates with orientation along airgap flux, that are necessary if the decoupler is to provide self-adaptive feature with respect to main flux saturation in the induction machine. It is shown that such an adaptive decoupling circuit can easily be derived. It asks for three nonlinear functional dependencies and provides full adaptation to instantaneous main flux saturation level in the machine. Verification is provided by simulation of a current-fed indirect vector controlled induction machine operating in the torque mode. The circuit enables very good matching between commanded and actual flux and torque values for any degree of the flux command variation. Possible simplifications of the full adaptive decoupling circuit are discussed as well and assessed by simulation. In particular, three different simplified structures that ask for reduced number of nonlinear functions, are discussed. It is shown that even the simplest structure where just one nonlinearity is retained provides superior responses compared to constant parameter decoupling circuit .

	A NEW DIRECT ROTOR FIELD ORIENTED SCHEME, USING THE THIRD HARMONIC COMPONENT OF THE AIR GAP FLUX By D. O. Kisch; N. Galan	[View] [Download]
Abstract: The paper presents a new direct rotor field oriented scheme for induction motor, based on determination of the position and amplitude of the air gap flux, from the third harmonic component of the stator voltage. This field control utilizes spatial saturation harmonic components rotating at synchronous frequency that are generated in the air gap flux when the induction motor is in a saturated condition. This method is used when the induçtion machine is wye connected, because the sum of the three phase voltages results in a signal dominated by the third harmonic component. The scheme uses a minimum number of sensors. The controller eliminates the flux sensing coils placed into the air gap on the wedges of the stator slots (or Hall elements in the air gap). This direct method of the flux estimation, in comparison with other direct or indirect methods, has the quality to be insensible to changes in the stator or rotor parameter's values. Simulated and experimental results showing the nature of the third harmonic voltage and the responses of the oriented scheme are presented.

	ROTOR FLUX ORIENTED TORQUE-CONTROL OF INDUCTION MACHINES BASED ON STATOR FLUX VECTOR CONTROL By D. Casadei; G. Grandi; G. Serra	[View] [Download]
Abstract: This paper describes a speed sensorless rotor flux oriented torque-control of induction machines which utilises stator flux components as control variables. Combining the advantages of rotor flux orientation and stator flux space vector control leads to high performance drives using a simple control scheme. This scheme is affected by total leakage inductance variations which determine detuned operation. A method is presented that provides the possibility to estimate the total leakage inductance besides the identification of stator self inductance. The effectiveness of the proposed system is verified by computer simulation and experimental tests.

	μ-ANALYSIS APPLIED TO FIELD ORIENTED CONTROL OF INDUCTION MOTOR By J.L. Thomas	[View] [Download]
Abstract: This paper presents an alternative method, the "μ-Analysis", for studying the robustness of the well-known field-oriented control of induction machine. The method, based on the structured singular value analysis, is used to analyse the robust stability and robust performance of closed-loop systems, here the motor with its associated control law, against several simultaneous plant uncertainties. The purpose of this paper is to give the worst-case effects of motor parameter variations on the stability and performance of the field-oriented drive structure. Furthermore, the author shows that the unmodeled drive dynamics can be introduced as unstructured uncertainties by using frequency-weighting transfer functions. This paper develops the nominal transfer function matrix of the entire indirect vector control scheme and gives the uncertainty block structure to perform the linear fractional transformation commonly defined in "μ-Analysis" theory. Simulation results are discussed and demonstrate the effectiveness of the proposed method applied to an industrial AC-drive example.

	STATOR PARAMETERS INFLUENCE ON THE FIELD-ORIENTED CONTROL TUNING By L. Loron	[View] [Download]
Abstract: High performance drives can be achieved by applying indirect field-oriented control to induction motors. To perform the field orientation and to obtain a fast and accurate torque control, a suitable model of the motor must be employed. A parametric model with only four electrical parameters is presented. This model is optimal for motor identification and controller implementation. Only two parameters of the model (the rotor parameters) are involved in the indirect field-oriented control when the motor is fed by a current regulated inverter. Several schemes can be employed to estimate these parameters; an extended Kalman filter is proposed because of its advantages and performance. However, the Kalman filter, like most motor identification schemes uses stator voltage and current measurements and relies on the stator parameters values, so errors in the stator parameters can alter the rotor parameter estimations. The stator parameters influence (during the estimation of the rotor parameters) is analyzed for steady-state and transient operating conditions.

	APPLICATION OF THE EXTENDED KALMAN FILTER TO PARAMETERS ESTIMATION OF INDUCTION MOTORS By L. Loron; G. Laliberté	[View] [Download]
Abstract: In this paper the extended Kalman filter theory is applied to the electrical parameter estimation of induction motors. This filter only uses machine quantities, which can be easily measured: the stator voltages and currents, and the rotor speed. The model of the induction motor is characterized by four parameters, which have to be simultaneously estimated. The filter settings are presented and discussed. These settings and the initial parameters set are deduced directly from the motor indicated characteristics. Experimental results show that the Kalman filter can perform a fast identification of the motor model. Then the model accuracy is evaluated by comparison of estimated and measured torque. Today the extended Kalman filter can be used as a parameter estimator for the tuning of the indirect field-oriented controller. Soon, it will also allow adaptive direct field-oriented control.

	SIMPLIFICATIONS ON FIELD ORIENTED CONTROL FOR LOW POWER VOLTAGE-SOURCE INDUCTION MOTOR DRIVES By J. P. Palma; J. G. Dente; F. J. Carvalhal	[View] [Download]
Abstract: The paper presents the last results of a research on the simplification of field orientation control methods for induction motor drives in stator, rotor, and air gap flux coordinates and using a PWM voltage-source inverter. The application of the input-output linearization method yields sophisticated control laws. Some simplification steps are taken next in order to achieve control procedures of decreasing complexity, specially devised for economy in low power drives. Steady state and dynamic performance are analytically studied, as well as robustness to the variation of parameters. The comparison with other related methods shows a progress in this field. Experimental results of speed and position control are reported from a prototype with a single eight-bit microcontroller, and confirm the expected performance.

	PARAMETER IDENTIFICATION OF AN INVERTER-FED INDUCTION MOTOR AT STANDSTILL WITH A CORRELATION METHOD By A. Bünte; H. Grotstollen	[View] [Download]
Abstract: Two methods to identify the electrical parameters and the magnetization curve of a voltage source inverter-fed induction motor (IM) at standstill will be presented. A special advantage of these methods is that the differences between the reference voltage values and the real phase voltage values caused by the unknown switching times of the PWM-inverter will be completely suppressed. Therefore a measurement of the phase voltage is not necessary and the parameters of the induction motor can be estimated with a high accuracy. Thus, no addltional hardware is necessary and therefore this identification rnethod is a good solution for use in commercial self-commissioning drives.

	IDENTIFICATION OF THE SATURATED MUTUAL INDUCTANCE OF AN ASYNCHRONOUS MOTOR AT STANDSTILL BY RECURSIVE LEAST SQUARES ALGORITHM By M. Ruff; H. Grotstollen	[View] [Download]
Abstract: A method is proposed which estimates the nonlinear function of the mutual inductance of an asynchronous motor. With the obtained function it is possible to calculate the control parameters, e.g. for a field oriented control. An important advantage of this method is that the identification of the mutual inductance can be taken automatically at standstill without locking the rotor mechanically. Therefore, the proposed method can be used for self commissioning of an induction motor drive. Simulation results are verified by a practical test using a squirrel cage motor.

	THE VECTOR CONTROLLED ASYNCHRONOUS ACTUATOR AND ITS USING POSSIBILITIES FOR EMBARKED APPLICATIONS By J. P. Vilain; E. Milent	[View] [Download]
Abstract: The vector-control awards to the induction motor a precision and qualities comparable with those of DC or brushless machines. For embarked applications, the shortcoming that appears in the usual proceedings is the necessity of maintaining a constant magnetic flux, therefore creating a permanent heat dissipation and consuming continuously energy from the supply. The aim of this study is to conciliate the high dynamical performances offered by the vector-control with the necessity of being sparing of embarked energy. A novel vector strategy is suggested, which allows to master the torque, to increase the efficiency and to nullify the consumption of energy while the motor is not being requested. The performances are illustrated by an orientation servo-control of the rear wheels for a four directional wheeled vehicle. The definition, simulation, and experimentation results, in steady and dynamical state, are presented. The concordance between simulation and results ratify the suggested strategies. Even for embarked applications, the induction motor, well-known for robustness, very cheap manufacturing and quasi-nonexistent maintenance, competes with DC or brushless machines.

	IMPROVED TORQUE AND FLUX VECTOR CONTROL OF PWM INVERTER-FED INDUCTION MOTOR DRIVE By M. P. Kazmierkowski; A. Kasprowicz	[View] [Download]
Abstract: In the paper a direct torque and stator flux vector control system is presented. The principle of this method was proposed by Takahashi and Noguchi in 1985. In contrast to the field oriented control, no coordinate transformation and current control loop is required. In practical application, however, problems occur with start and operation at zero speed region. This paper shows how by introducing an additional carrier signal to the torque controller input, the robust start and improved operation at low speed region can be achieved. The simulation and experimental results which illustrate the performances of the system are presented. Also, the nomogram for controller design and comparison with most popular current type of indirect field oriented control are presented.

	COMPUTER SIMULATION OF A CYCLOCONVERTER DRIVE AND DEVELOPMENT OF A FULL DIGITAL FIELD ORIENTED CONTROL By E. Chiesa; A. Monti; M. Matuonto	[View] [Download]
Abstract: The paper reports the results of a research in the simulation and control fields, for the analysis of the operation of cycloconverter drives and the design of a new advanced digital control for such equipments. It describes in detail a simulation tool realised in C language to study power and control problems arising when using a cycloconverter to feed an AC motor. The power section is represented by means of a new model that allows easy adaptation to various circuit structures in steady state, transient and fault conditions. lt also allows immediate calculation of electrical parameters sizing and cost of the components. Conceming the control section, the simulator allows the analysis of hardware and software interferences; a discrete-time model is used so that the same C language routines are valid and portable on the real system. As a result of this research, Ansaldo Industria, in its Milan research centre, is on the way to test the first prototype of a 150 kW drive, based on a full digital controlled six pulse no-circulating current cycloconverter supplying an induction motor with Field Oriented Control.

	A SINGLE PHASE INPUT CYCLOCONVERTER DRIVING A THREE PHASE MOTOR By J. Zhang; G. P. Hunter; V. S. Ramsden	[View] [Download]
Abstract: The paper presents a 1-phase to 3-phase cycloconverter suitable for driving an induction motor. The input of the cycloconverter is a single phase supply of 240V, 50Hz, and its output is a 3-phase supply with variable voltage and variable frequency (VVVF) up to 25Hz. Using a double integral control technique, a 1-ph to 3-ph modulation method is proposed so the motor flux follows a sinusoidal reference. Only six naturally commutated triacs are used in the power circuit, so the resulting cycloconverter-motor drive is cheap, compact and efficient. Software in C has been written for both simulation and real time control. The simulation is used to predict the performance of the cycloconverter and induction motor.

	A NOVEL CYCLOCONVERTER BASED ON MICROPROCESSOR DIGITAL CONTROL By S. Hexu; Z. Xiaojie; C. Yan; L. Zongfu	[View] [Download]
Abstract: In view of the relative advantage of using a current-source converter for many high-performance drives, a novel cycloconverter that is composed of double H bridge converters has been developed as a three-phase sinusoidal current source of adjustable frequency. The power main circuit contains 20 thyristors and current control for two-phase H bridge converter are used to generate symmetrical three-phase currents. In this paper, we present the power main circuit, the operation pattern and discuss a microprocessor-based digital control cycloconverter (DCC) system that ensures high quality output. Among other aspects, the digital system facilitates stepping sinusoidal current control for the total distortion factor improvement, the method of current zero crossing, discrete compensation for feedback control, and online identification of the load parameter. The macromodel of thyristor for analog power circuit simulation using PSPICE has been devoloped. The novel cycloconverter bas been experimentalized on R-L load. The control strategies are elaborated upon, and simulation and experimental results are presented.