EPE Association: EPE 1993 - 23 - Lecture Session L8b: CONTROL: TRANSDUCERS AND OBSERVERS

EPE 1993 - 23 - Lecture Session L8b: CONTROL: TRANSDUCERS AND OBSERVERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 23 - Lecture Session L8b: CONTROL: TRANSDUCERS AND OBSERVERS

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   CONTACTLESS HIGH SPEED SIGNAL TRANSMISSION INTEGRATED IN A COMPACT ROTATABLE POWER TRANSFORMER
By A. Esser; A. Nagel [View]
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Abstract: In many technical units containing rotatable parts it is necessary to transmit energy and signals through the joints. Today systems for rotatable applications use slip rings or movable cables, which limit lifetime and flexibility. An inductively coupled energy transmission system as proposed in [5,6], is able to transmit several kilowatts through a rotatable joint without any mechanical stress or aging using a rotatable pot core transformer. The paper describes a new contactless signal transmission system inside this transformer. The system offers three independent analog signal transmission channels with a wide bandwidth. These are able to transmit digital information with data rates up to several MBit/sec. The bit-error-rate is extremely low even without using any error correction. This system may be used for any application demanding high reliability, such as robots, satellites or rotating measurement systems.

   Single Sensor Current Control of AC Servodrives Using Digital Signal Processors
By J. F. Moynihan; S. Bolognani; R. C. Kavanagh; M. G. Egan; J. M. D. Murphy [View]
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Abstract: Successful operation of ac servodrives requires precise control of the motor line currents. The emergence of fast digital signal processors (DSP) permits real-time digital current control. However, expensive current transducers are required to sense the instantaneous currents in at least two, and often the three, stator phases. A predictive current controller for the permanent magnet synchronous motor (PMSM) is presented which uses a space vector modulation (SVM) strategy to determine the switching instants of the voltage source inverter (VSI). Compensation of the inverter switching dead times is also incorporated. An innovative current feedback scheme using a single current sensor placed in the inverter dc link is proposed. This feedback mechanism employs a state observer to ensure reliable feedback signals under all operating conditions. The paper presents detailed algorithm development, describes the prototype DSP-based hardware system and includes experimental verification of the proposed control structure.

   AN OPTIMIZED, ADAPTlVE, REDUCED-ORDER FLUX OBSERVER
By P. Claessens; P. Mathys; J. Bou Saada; P. Colignon [View]
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Abstract: This paper deals with a new, robust and adaptative state observer for the torque control of asynchronous machines used in railways. Vector control requires an accurate estimation of the flux vector through a model. The first problem is the robustness of the observer since some parameters of the model are varying a lot with temperature and speed and since some noise is always present on measurements. The second problem is real time since all computations have to be performed in a very short time (less than 100 μs for a 200Hz machine). We have developed a reduced-order model that can observe a linear combination of the rotor flux vector and the stator current vector. The two coefficients of this combination give two degrees of freedom to optimize the robustness of the observer with respect to the errors on the most critical parameters and measures i.e. errors on rotor resistance, stator resistance and stator voltage. This method allows to construct an adaptative optimized observer in function of speed and load. The optimal trajectory in the plane of the two parameters gives an easy graphical interpretation. Experimental results show significant improvements compared with previous methods.

   ROBUST OBSERVER BASED VSS TRACKING CONTROL OF AN IM SERVODRIVE
By K. Jezernik; V. Volcanjk; A. Hren; B. Premzl [View]
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Abstract: A control approach for robust accurate trajectory tracking of IM servodrive based on the Variable Structure System (VSS) theory is described. The modified sliding observer of the rotor magnetizing current is used to improve flux control. The synthesis of the VSS controller for motion control is based on the PI estimator of torque disturbance and estimated value of acceleration. The developed control algorithm eliminates the initial conditions mismatch, parameter variations and external influences, and also assures accurate trajectory tracking by the prescribed dynamics. The validity of the proposed algorithm was verified by simulation and experiment. The experimental system consists of a transputer T 805 and a microcontroller MC 68000 and enables parallel processing.

EPE 1993 - 23 - Lecture Session L8b: CONTROL: TRANSDUCERS AND OBSERVERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 23 - Lecture Session L8b: CONTROL: TRANSDUCERS AND OBSERVERS
	[return to parent folder]

	CONTACTLESS HIGH SPEED SIGNAL TRANSMISSION INTEGRATED IN A COMPACT ROTATABLE POWER TRANSFORMER By A. Esser; A. Nagel	[View] [Download]
Abstract: In many technical units containing rotatable parts it is necessary to transmit energy and signals through the joints. Today systems for rotatable applications use slip rings or movable cables, which limit lifetime and flexibility. An inductively coupled energy transmission system as proposed in [5,6], is able to transmit several kilowatts through a rotatable joint without any mechanical stress or aging using a rotatable pot core transformer. The paper describes a new contactless signal transmission system inside this transformer. The system offers three independent analog signal transmission channels with a wide bandwidth. These are able to transmit digital information with data rates up to several MBit/sec. The bit-error-rate is extremely low even without using any error correction. This system may be used for any application demanding high reliability, such as robots, satellites or rotating measurement systems.

	Single Sensor Current Control of AC Servodrives Using Digital Signal Processors By J. F. Moynihan; S. Bolognani; R. C. Kavanagh; M. G. Egan; J. M. D. Murphy	[View] [Download]
Abstract: Successful operation of ac servodrives requires precise control of the motor line currents. The emergence of fast digital signal processors (DSP) permits real-time digital current control. However, expensive current transducers are required to sense the instantaneous currents in at least two, and often the three, stator phases. A predictive current controller for the permanent magnet synchronous motor (PMSM) is presented which uses a space vector modulation (SVM) strategy to determine the switching instants of the voltage source inverter (VSI). Compensation of the inverter switching dead times is also incorporated. An innovative current feedback scheme using a single current sensor placed in the inverter dc link is proposed. This feedback mechanism employs a state observer to ensure reliable feedback signals under all operating conditions. The paper presents detailed algorithm development, describes the prototype DSP-based hardware system and includes experimental verification of the proposed control structure.

	AN OPTIMIZED, ADAPTlVE, REDUCED-ORDER FLUX OBSERVER By P. Claessens; P. Mathys; J. Bou Saada; P. Colignon	[View] [Download]
Abstract: This paper deals with a new, robust and adaptative state observer for the torque control of asynchronous machines used in railways. Vector control requires an accurate estimation of the flux vector through a model. The first problem is the robustness of the observer since some parameters of the model are varying a lot with temperature and speed and since some noise is always present on measurements. The second problem is real time since all computations have to be performed in a very short time (less than 100 μs for a 200Hz machine). We have developed a reduced-order model that can observe a linear combination of the rotor flux vector and the stator current vector. The two coefficients of this combination give two degrees of freedom to optimize the robustness of the observer with respect to the errors on the most critical parameters and measures i.e. errors on rotor resistance, stator resistance and stator voltage. This method allows to construct an adaptative optimized observer in function of speed and load. The optimal trajectory in the plane of the two parameters gives an easy graphical interpretation. Experimental results show significant improvements compared with previous methods.

	ROBUST OBSERVER BASED VSS TRACKING CONTROL OF AN IM SERVODRIVE By K. Jezernik; V. Volcanjk; A. Hren; B. Premzl	[View] [Download]
Abstract: A control approach for robust accurate trajectory tracking of IM servodrive based on the Variable Structure System (VSS) theory is described. The modified sliding observer of the rotor magnetizing current is used to improve flux control. The synthesis of the VSS controller for motion control is based on the PI estimator of torque disturbance and estimated value of acceleration. The developed control algorithm eliminates the initial conditions mismatch, parameter variations and external influences, and also assures accurate trajectory tracking by the prescribed dynamics. The validity of the proposed algorithm was verified by simulation and experiment. The experimental system consists of a transputer T 805 and a microcontroller MC 68000 and enables parallel processing.