EPE Association: EPE 1993 - 14 - Lecture Session L5b: CONTROL: TUNING ESTIMATION SENSITIVITY

EPE 1993 - 14 - Lecture Session L5b: CONTROL: TUNING ESTIMATION SENSITIVITY
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 14 - Lecture Session L5b: CONTROL: TUNING ESTIMATION SENSITIVITY

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   STATOR RESISTANCE TUNING IN A STATOR FLUX FIELD ORIENTED DRIVE USING AN INSTANTANEOUS HYBRID FLUX ESTIMATOR
By Thomas G. Habetler; Francesco Profumo; Giovanni Griva; Michele Pastorelli; Alberto Bettini [View]
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Abstract: A self-tuning control scheme for stator flux field oriented induction machine drives in electric vehicles operating over a wide speed range is discussed in this paper. The stator flux can be determined accurately from the terminal voltage when the machine is operating at high speed. However, at low speed, the stator resistance must be known to calculate the stator flux. The problem of calculating the stator flux accurately over the entire speed range is addressed. The rotor flux can be found from the machine speed and the rotor time constant. The stator flux, at low speed, is then calculated directly from the rotor flux. By alternating between these two methods of determining the stator flux, a self-tuning operation is achieved, wherein the stator and rotor resistances are periodically updated. Since both methods of determining the stator flux are forced to track one another, a smooth transition between flux estimators is obtained. The torque and flux are then controlled in a dead beat fashion. Good torque control over a wide speed range can therefore be obtained. With the proposed scheme, the advantages of direct torque control are obtained over the entire speed range with the addition of a speed sensor.

   APPLICATION OF AN "ELECTRONIC STATOR RESISTANCE" IN VSI FED FIELD ORIENTED SYNCHRONOUS MACHINES
By Zhu Shihe; F. Blaschke; A. Vandenput; W. Geysen [View]
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Abstract: This paper describes the concept of the so called "electronic stator resistance" and its applications. In the field orientation control circuit of a voltage source inverter (VSI) fed synchronous machine (SM), the estimated values of the resistance of both the stator and the damper winding are used. Detuning of any resistance value influences the performance of the system. Instead of the parameter identification technique an "electronic stator resistance", which in fact functions as a negative current feedback loop, can be used as a countermeasure to the stator resistance detuning. This method is simple, effective and easy to be realized. The study also shows that, to ensure the stability, the stator resistance should be tuned according to the cold machine.

   PARAMETER SENSITIVITY STUDIES FOR INDUCITON MOTOR PARAMETER IDENTIFICATION USING EXTENDED KALMAN FILTERS
By R. S. Pena; G. M. Asher [View]
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Abstract: The simulation results of the convergence characteristics of the Extended Kalman Filter (EKF), in estimating the rotor retistance and the magnetizing inductance in an induction machine under steady state and transient conditions are presented. The performance of the filter to a step response of rotor resistance and magnetizing inductance is shown. The sensitivity of both algorithms to motor parameter variations and rotor speed error are analysed and compared. The EKF techniques are critically discussed in the light of increasing interest in the method.

   ACCURACY LIMITATIONS OF VELOCITY AND FLUX ESTIMATION IN DIRECT FIELD ORIENTED INDUCTION MACHINES
By P. L. Jansen; R. D. Lorenz [View]
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Abstract: This paper focuses on the accuracy and robustness limitations of direct field oriented (DFO) systems incorporating velocity estimation that are based solely upon measured stator voltages and currents. The analysis is limited to integrated velocity and flux estimation methods that rely upon the induction machine back emf. After assessing the limitations of a model reference adaptive controller (MRAC) approach, an improved topology utilizing an integrated closed-loop flux observer and a mechanical system model is proposed and experimentally verified. Given some knowledge of the machine load, the proposed observer can potentially improve both the velocity estimation dynamics and the transient low speed field orientation. However, it does not overcome the fundamental lack of robustness at zero speed and loss of accuracy due to parameter sensitivity. Finally, the existence of the same limitations in altemative approaches to velocity estimation and field orientation is discussed.

EPE 1993 - 14 - Lecture Session L5b: CONTROL: TUNING ESTIMATION SENSITIVITY
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 14 - Lecture Session L5b: CONTROL: TUNING ESTIMATION SENSITIVITY
	[return to parent folder]

	STATOR RESISTANCE TUNING IN A STATOR FLUX FIELD ORIENTED DRIVE USING AN INSTANTANEOUS HYBRID FLUX ESTIMATOR By Thomas G. Habetler; Francesco Profumo; Giovanni Griva; Michele Pastorelli; Alberto Bettini	[View] [Download]
Abstract: A self-tuning control scheme for stator flux field oriented induction machine drives in electric vehicles operating over a wide speed range is discussed in this paper. The stator flux can be determined accurately from the terminal voltage when the machine is operating at high speed. However, at low speed, the stator resistance must be known to calculate the stator flux. The problem of calculating the stator flux accurately over the entire speed range is addressed. The rotor flux can be found from the machine speed and the rotor time constant. The stator flux, at low speed, is then calculated directly from the rotor flux. By alternating between these two methods of determining the stator flux, a self-tuning operation is achieved, wherein the stator and rotor resistances are periodically updated. Since both methods of determining the stator flux are forced to track one another, a smooth transition between flux estimators is obtained. The torque and flux are then controlled in a dead beat fashion. Good torque control over a wide speed range can therefore be obtained. With the proposed scheme, the advantages of direct torque control are obtained over the entire speed range with the addition of a speed sensor.

	APPLICATION OF AN "ELECTRONIC STATOR RESISTANCE" IN VSI FED FIELD ORIENTED SYNCHRONOUS MACHINES By Zhu Shihe; F. Blaschke; A. Vandenput; W. Geysen	[View] [Download]
Abstract: This paper describes the concept of the so called "electronic stator resistance" and its applications. In the field orientation control circuit of a voltage source inverter (VSI) fed synchronous machine (SM), the estimated values of the resistance of both the stator and the damper winding are used. Detuning of any resistance value influences the performance of the system. Instead of the parameter identification technique an "electronic stator resistance", which in fact functions as a negative current feedback loop, can be used as a countermeasure to the stator resistance detuning. This method is simple, effective and easy to be realized. The study also shows that, to ensure the stability, the stator resistance should be tuned according to the cold machine.

	PARAMETER SENSITIVITY STUDIES FOR INDUCITON MOTOR PARAMETER IDENTIFICATION USING EXTENDED KALMAN FILTERS By R. S. Pena; G. M. Asher	[View] [Download]
Abstract: The simulation results of the convergence characteristics of the Extended Kalman Filter (EKF), in estimating the rotor retistance and the magnetizing inductance in an induction machine under steady state and transient conditions are presented. The performance of the filter to a step response of rotor resistance and magnetizing inductance is shown. The sensitivity of both algorithms to motor parameter variations and rotor speed error are analysed and compared. The EKF techniques are critically discussed in the light of increasing interest in the method.

	ACCURACY LIMITATIONS OF VELOCITY AND FLUX ESTIMATION IN DIRECT FIELD ORIENTED INDUCTION MACHINES By P. L. Jansen; R. D. Lorenz	[View] [Download]
Abstract: This paper focuses on the accuracy and robustness limitations of direct field oriented (DFO) systems incorporating velocity estimation that are based solely upon measured stator voltages and currents. The analysis is limited to integrated velocity and flux estimation methods that rely upon the induction machine back emf. After assessing the limitations of a model reference adaptive controller (MRAC) approach, an improved topology utilizing an integrated closed-loop flux observer and a mechanical system model is proposed and experimentally verified. Given some knowledge of the machine load, the proposed observer can potentially improve both the velocity estimation dynamics and the transient low speed field orientation. However, it does not overcome the fundamental lack of robustness at zero speed and loss of accuracy due to parameter sensitivity. Finally, the existence of the same limitations in altemative approaches to velocity estimation and field orientation is discussed.