EPE Association: EPE 1997 – 11: Lecture Session L3c: SERVO DRIVES

EPE 1997 – 11: Lecture Session L3c: SERVO DRIVES
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   SENSORLESS FIELD ORIENTED SPEED CONTROL OF A HYBRIJ) STEPPER MOTOR USING AN EXTENDED KALMAN FILTER
By C. Obermeier; H. Kellermann; G. Brandenburg; J. Heinzl [View]
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Abstract: Applying the principle of field orientation and providing a closed-loop speed control the stepper motor becomes a high-dynamic, robust, four-quadrant ac-servo drive considerably differing from its normal use in the open-loop control mode. However, improving the motor in this way, a rotor position encoder is necessary. This can be avoided if an extended Kalman filter is used which reconstructs the state variables by only measuring the phase vollages and currents. This filter requires a detailed mathematical description of the stepper motor. An additional disturbance model. considering the load torque influence, is introduced into the filter. The discrete Kalman filter algorithm is implemented in a completely digital field oriented state control of the speed. Experimental results confirm that this four-quadrant sensorless drive covers high range of speeds, reaching nearly standstill. It can replace the mechanically commutated d.c. machines mostly used in lowpower range which is bigger in size and has a limited life span.

   AN ALTERNATIVE METHOD TO SERVOMOTOR DRIVE TORQUE RIPPLE ASSESSMENT
By Philip C. Kjaer [View]
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Abstract: This paper presents a new, alternative method to assess the torque ripple in a wide range of servo motor drives, showing the servo motor torque demand variation vs. rotor position when subject to a constant shaft (load) torque. Standstill measurements avoid the problems of dynamic nature found in many in-line torque measuring techniques. Results obtained from a switched reluctance motor servo drive are included, and confirm the applicability of the proposed technique.

   DETECTION OF THE STARTING ROTOR ANGLE OF OF A PMSM AT STANDSTILL
By C. Brunotte; W. Schumacher [View]
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Abstract: A simple method to measure the starting rotor angle of a PMSM is described. It is based on the different saturation of the inductances, which depends on the present rotor position. Hence a movement of the motor is not necessary. The accuracy of the measurement is around ±5 degrees.

   STATE OF THE ART OF SMOOTH TORQUE CONTROLLERS
By E. Favre; J.-M. Mozzon; E. Von Siebenthal; A. Crausaz [View]
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Abstract: A drawback of permanent magnet synchronous motors is to provide a non-constant output torque when driven with classical electronic drivers. For specific applications, a ripple free torque has nevertheless to be achieved and the use of a dedicated electronic driver becomes mandatory. This typically applies when a peak to peak torque ripple lower than 10% is expected, even if this level of ripple seems easily achievable with conventional technologies. This paper trades-off the different solutions generally considered for the torque ripple control. In particular, it shows the practical limits of theoretically simple motor-electronic approaches (e.g. the combination of a square current driver with a motor having a trapezium back emf shapes) and emphasizes on the need of an efficient electronic controller. Results of several practical experiences are also presented.

EPE 1997 – 11: Lecture Session L3c: SERVO DRIVES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1997 - Conference > EPE 1997 – 11: Lecture Session L3c: SERVO DRIVES
	[return to parent folder]

	SENSORLESS FIELD ORIENTED SPEED CONTROL OF A HYBRIJ) STEPPER MOTOR USING AN EXTENDED KALMAN FILTER By C. Obermeier; H. Kellermann; G. Brandenburg; J. Heinzl	[View] [Download]
Abstract: Applying the principle of field orientation and providing a closed-loop speed control the stepper motor becomes a high-dynamic, robust, four-quadrant ac-servo drive considerably differing from its normal use in the open-loop control mode. However, improving the motor in this way, a rotor position encoder is necessary. This can be avoided if an extended Kalman filter is used which reconstructs the state variables by only measuring the phase vollages and currents. This filter requires a detailed mathematical description of the stepper motor. An additional disturbance model. considering the load torque influence, is introduced into the filter. The discrete Kalman filter algorithm is implemented in a completely digital field oriented state control of the speed. Experimental results confirm that this four-quadrant sensorless drive covers high range of speeds, reaching nearly standstill. It can replace the mechanically commutated d.c. machines mostly used in lowpower range which is bigger in size and has a limited life span.

	AN ALTERNATIVE METHOD TO SERVOMOTOR DRIVE TORQUE RIPPLE ASSESSMENT By Philip C. Kjaer	[View] [Download]
Abstract: This paper presents a new, alternative method to assess the torque ripple in a wide range of servo motor drives, showing the servo motor torque demand variation vs. rotor position when subject to a constant shaft (load) torque. Standstill measurements avoid the problems of dynamic nature found in many in-line torque measuring techniques. Results obtained from a switched reluctance motor servo drive are included, and confirm the applicability of the proposed technique.

	DETECTION OF THE STARTING ROTOR ANGLE OF OF A PMSM AT STANDSTILL By C. Brunotte; W. Schumacher	[View] [Download]
Abstract: A simple method to measure the starting rotor angle of a PMSM is described. It is based on the different saturation of the inductances, which depends on the present rotor position. Hence a movement of the motor is not necessary. The accuracy of the measurement is around ±5 degrees.

	STATE OF THE ART OF SMOOTH TORQUE CONTROLLERS By E. Favre; J.-M. Mozzon; E. Von Siebenthal; A. Crausaz	[View] [Download]
Abstract: A drawback of permanent magnet synchronous motors is to provide a non-constant output torque when driven with classical electronic drivers. For specific applications, a ripple free torque has nevertheless to be achieved and the use of a dedicated electronic driver becomes mandatory. This typically applies when a peak to peak torque ripple lower than 10% is expected, even if this level of ripple seems easily achievable with conventional technologies. This paper trades-off the different solutions generally considered for the torque ripple control. In particular, it shows the practical limits of theoretically simple motor-electronic approaches (e.g. the combination of a square current driver with a motor having a trapezium back emf shapes) and emphasizes on the need of an efficient electronic controller. Results of several practical experiences are also presented.