EPE Association: EPE 1989 - 40 - Dialogue Session 3.2: SIGNAL PROCESSING

EPE 1989 - 40 - Dialogue Session 3.2: SIGNAL PROCESSING
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   HIGH PRECISION TORQUE-CALCULATOR FOR INVERTER-FED INDUCTION MOTORS
By H. Berger; K. Schiftner [View]
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Abstract: A digital torque-computer, which calculates the shaft torque of current-source-inverter fed squirrel-cage induction motors, is presented, By using the method of power balance only the measurement of electrical quantities is required. Compared to commonly used techniques based on mechanical principles the digital method provides the advantages of simple installing, high reliability and negligible costs of maintenance. The induction power, which determines the electromagnetic torque is evaluated from the d.c.-link power using machine and d.c./a.c.-converter characteristics available from the manufacturer. In order to achieve high accuracy additional losses, which are only known exactly in its structure, are modeled with respect to the stator current. The unknown frequency-depending parameter-functions are determined by automatical calibration.

   REPLACING A THREE PHASE SYSTEM BY ONE TRANSFER FUNCTION FOR DESIGNING CONTROLLERS
By P. Leyten [View]
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Abstract: For designing an optimum control system to control the voltages or currents generated by an inverter it is convenient when all parts of the control loop can be regarded as linear and time-invariant. However, the control loop contains the inverter, the circuits connected with the three phases of the inverter and a rectifier to measure the voltage or current that has to be controlled. This part of the control loop contains non-linear and time-variant elements. A method is presented to substitute the three phase inverter connected with three similar circuits and the measurement-rectifier by a linear and time-invariant system. This system is described by a transfer function. The substitute transfer function can easily be derived from the transfer function of the circuit that is present in all three phases of the inverter ( the load) and proves to be very accurate in describing the original system.

   UNIVERSAL PWM INVERTER FED ASYNCHRONOUS DRIVE WITH A DYNAMIC FLUX CONTROL
By M . Pietrzak-David, B. de Fornel [View]
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Abstract: In this paper, the authors present the concept of a universal numerical control designed for an asynchronous drive fed by a pulse width modulated (PWM) inverter. The proposed command structure is hierarchical, and is equipped with two operating levels. After having presented the complete process model, the authors proceed to its linearisation and its reduction. Different dynamic flux control laws are proposed according to the methods of flux reconstitution. Finally, the control of mechanical machine mode is examinated, permitting torque, speed and position control. The different results obtained from the simulation and the experimental realization permit verification of the validity of the proposed digital controls.

   SPEED-RATE CONTROL EFFECT ON SPEED CONTROL SYSTEM PERFORMANCE IN A SPEED REGULATOR WITH A CURRENT CONTROLLER
By K. Kamiyama; K. Saito; M. Tobise; K. Mizuno; T. Okuyama [View]
[Download]

Abstract: A speed-rate control method is proposed for a speed regulator. The speed regulator is realized using speed-rate and current control loops. The control method is based on a feedback control strategy. Its features include an improved dynamic speed response and a robust capability for both speed reference and disturbance torque. It also suppresses torsional vibration effectively. Comparisons with and without the speed-rate controller and with the torque observer regarding speed control system performance are made. The speed control system performance is analyzed by a transfer function expression and digital simulations, with the latter being in detail.

   THE TORQUE LOAD OBSERVERS IN MULTlMOTOR DC THYRISTOR CONVERTER DRIVE
By Maciej Tondos; Herbert Widlok [View]
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Abstract: In the paper a short description of torque load observers application to multimotor dc drive system is presented. Armatures of all the motors were supplied from a common reversible converter in this drive and excitations are supplied from individual thyristor converters with suitable control systems. An approach to modified torque load observers application in this non-typical drive was done. Using these observers in speed control and stabilization systems improves the control quality factor several times. Some results of digital simulation and laboratory tests also are shown.

   ESTIMATION OF PARAMETERS AND LOAD TORQUE OF A THYRISTOR DRIVEN DC MOTOR DRIVE
By M. Milanovic; K. Jezernik; A. Planinc [View]
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Abstract: This paper describes a method of estimating parameters of a control loop and an observer for unmeasurable variables which influence the load torque of motor axis. Our method is based on a processing of measured mean values of the measurable drive's state variables. In spite of the weaknesses associated with the use of deterministic signals for parameter estimation, we chose this method because of the realizability of our algorithm on microprocessor controlled motor drive. This procedure produces a robust control algorithm which greatly enchances control of plants with variable parameters.

EPE 1989 - 40 - Dialogue Session 3.2: SIGNAL PROCESSING
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 40 - Dialogue Session 3.2: SIGNAL PROCESSING
	[return to parent folder]

	HIGH PRECISION TORQUE-CALCULATOR FOR INVERTER-FED INDUCTION MOTORS By H. Berger; K. Schiftner	[View] [Download]
Abstract: A digital torque-computer, which calculates the shaft torque of current-source-inverter fed squirrel-cage induction motors, is presented, By using the method of power balance only the measurement of electrical quantities is required. Compared to commonly used techniques based on mechanical principles the digital method provides the advantages of simple installing, high reliability and negligible costs of maintenance. The induction power, which determines the electromagnetic torque is evaluated from the d.c.-link power using machine and d.c./a.c.-converter characteristics available from the manufacturer. In order to achieve high accuracy additional losses, which are only known exactly in its structure, are modeled with respect to the stator current. The unknown frequency-depending parameter-functions are determined by automatical calibration.

	REPLACING A THREE PHASE SYSTEM BY ONE TRANSFER FUNCTION FOR DESIGNING CONTROLLERS By P. Leyten	[View] [Download]
Abstract: For designing an optimum control system to control the voltages or currents generated by an inverter it is convenient when all parts of the control loop can be regarded as linear and time-invariant. However, the control loop contains the inverter, the circuits connected with the three phases of the inverter and a rectifier to measure the voltage or current that has to be controlled. This part of the control loop contains non-linear and time-variant elements. A method is presented to substitute the three phase inverter connected with three similar circuits and the measurement-rectifier by a linear and time-invariant system. This system is described by a transfer function. The substitute transfer function can easily be derived from the transfer function of the circuit that is present in all three phases of the inverter ( the load) and proves to be very accurate in describing the original system.

	UNIVERSAL PWM INVERTER FED ASYNCHRONOUS DRIVE WITH A DYNAMIC FLUX CONTROL By M . Pietrzak-David, B. de Fornel	[View] [Download]
Abstract: In this paper, the authors present the concept of a universal numerical control designed for an asynchronous drive fed by a pulse width modulated (PWM) inverter. The proposed command structure is hierarchical, and is equipped with two operating levels. After having presented the complete process model, the authors proceed to its linearisation and its reduction. Different dynamic flux control laws are proposed according to the methods of flux reconstitution. Finally, the control of mechanical machine mode is examinated, permitting torque, speed and position control. The different results obtained from the simulation and the experimental realization permit verification of the validity of the proposed digital controls.

	SPEED-RATE CONTROL EFFECT ON SPEED CONTROL SYSTEM PERFORMANCE IN A SPEED REGULATOR WITH A CURRENT CONTROLLER By K. Kamiyama; K. Saito; M. Tobise; K. Mizuno; T. Okuyama	[View] [Download]
Abstract: A speed-rate control method is proposed for a speed regulator. The speed regulator is realized using speed-rate and current control loops. The control method is based on a feedback control strategy. Its features include an improved dynamic speed response and a robust capability for both speed reference and disturbance torque. It also suppresses torsional vibration effectively. Comparisons with and without the speed-rate controller and with the torque observer regarding speed control system performance are made. The speed control system performance is analyzed by a transfer function expression and digital simulations, with the latter being in detail.

	THE TORQUE LOAD OBSERVERS IN MULTlMOTOR DC THYRISTOR CONVERTER DRIVE By Maciej Tondos; Herbert Widlok	[View] [Download]
Abstract: In the paper a short description of torque load observers application to multimotor dc drive system is presented. Armatures of all the motors were supplied from a common reversible converter in this drive and excitations are supplied from individual thyristor converters with suitable control systems. An approach to modified torque load observers application in this non-typical drive was done. Using these observers in speed control and stabilization systems improves the control quality factor several times. Some results of digital simulation and laboratory tests also are shown.

	ESTIMATION OF PARAMETERS AND LOAD TORQUE OF A THYRISTOR DRIVEN DC MOTOR DRIVE By M. Milanovic; K. Jezernik; A. Planinc	[View] [Download]
Abstract: This paper describes a method of estimating parameters of a control loop and an observer for unmeasurable variables which influence the load torque of motor axis. Our method is based on a processing of measured mean values of the measurable drive's state variables. In spite of the weaknesses associated with the use of deterministic signals for parameter estimation, we chose this method because of the realizability of our algorithm on microprocessor controlled motor drive. This procedure produces a robust control algorithm which greatly enchances control of plants with variable parameters.