EPE Association: EPE 1991 - 44 - Session 4.11: FIELD ORIENTED CONTROL 2

EPE 1991 - 44 - Session 4.11: FIELD ORIENTED CONTROL 2
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   IMPROVEMENT OF ROBUSTNESS ON SPEED SENSORLESS VECTOR CONTROL OF INDUCTION MOTOR
By Ichiroh Miyashita; Youichi Ohmori [View]
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Abstract: This paper discusses high-speed, high-precision, robust torque and speed control techniques for a speed sensorless induction motor based on the instantaneous flux and slip calculation. The torque control system has proved to be insensitive to primary resistance (R1) variations and entirely robust to secondary resistance (R2) variations. However, the speed control system is only insensitive to R1 and still remains sensitive to R2 variations. A new method to solve this problem, with R2 identification, is proposed, using a specified harmonic component due to rotor slotting. The real R2 value is obtained during on-line operation by correcting the nominal R2 value according to the error signal between the calculated speed and actual speed detected from the frequency of the harmonic.

   FIELD-WEAKENING WITH THE DIRECT SELF CONTROL (DSC) AS A CONTROL-SCHEME FOR HIGH POWER THREE-LEVEL GTO INVERTERS
By F. Springmeier; J. K. Steinke [View]
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Abstract: For inverters in the MW-range the switching frequency of each valve is limited to 100 - 300Hz. A very good control method if working with low switching-frequencies is Direct Self Control (DSC), developed 1984 by M. Depenbrock for voltage source inverter-fed induction motors. This control algorithm directly determines the switching states of the inverter and gives an optimal characteristic for stator flux and torque control. Compared to a conventional two-level inverter, smoother waveshapes of current, flux and torque are obtained by using a three-level GTO inverter. Direct Self Control modified for application with a three-level inverter also has to allow field-weakening which is necessary when stator-frequency is above rated stator frequency of the motor. This control scheme and practical results of its application, measured at a 20KW inverter-motor test-system, are discussed in this paper.

   Low Switching Frequency High-Power lnverter Drive Based on Field-Oriented Pulsewidth Modulation
By Ashwin Khambadkone; Joachim Holtz [View]
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Abstract: In megawatt rated inverter-fed induction motor drive systems, the GTO switching losses account for a considerable amount of the total losses. Hence, the switching frequency in such systems must be kept at a low value of only a few hundred Hertz. To avoid undesired torque harmonics under such operating conditions, the pulse control of the inverter is made dependent on the orientation of the rotor flux orientation of the drive machine. This method transfers a major portion of the unavoidable current distortions into the field axis where they have no influence on the machine torque. An optimal trajectory oriented control is presented which achieves low switching frequency at low torque and current harmonics and exhibits a very fast dynamic response. The performance of this method is demonstrated by measured results from a 30-kW model drive.

   A STATOR FLUX ORIENTED SPEED CONTROL OF INDUCTION MACHINE WITHOUT SPEED SENSOR
By Hyung-Soo Mok; Joohn-Sheok Kim; Young-Real Kim; Min-Ho Park; Seung-Ki Sul [View]
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Abstract: This paper describes the stator flux oriented speed control strategy with the speed estimation algorithm. And the method of adapting rotor time constant variations is proposed. Since the estimation of the stator flux is independent of the leakage inductance, our scheme uses direct stator flux oriented control method. A decoupler is realized to minimize the coupling between d-axis and q-axis component of the stator currents in the stator flux reference frame. The effectiveness of the proposed system is verified by computer simulation.

   A NEW VECTOR CONTROL SCHEME FOR INVERTER-FED PERMANENT MAGNET SYNCHRONOUS MOTOR USING DSP
By J. Moerschell; M. Tursini [View]
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Abstract: This paper presents a new vector control scheme for inverter-fed permanent magnet synchronous motor suitable for DSP implementation. The design of the control scheme is carried out considering the model of the motor in a stationary two-phases frame of reference. This in order to work directly with measurable currents and voltages. The electromagnetic torque and the reactive power are directly controlled by hysteresis regulators whose outputs are used to generate the command signals of the three-phase inverter. Position sensor and coordinate transformations are not needed, then the signal processing equipment is very simple and the calculation time is reduced. Experimental tests in which the proposed scheme is used to realize the control of the motor with unity power factor are shown.

   Comparison of Universal Field Oriented (UFO) Controllers in Different Reference Frames
By F. Profumo; M. Pastorelli; P. Ferraris; R. W. De Doncker [View]
[Download]

Abstract: The principle of the Universal Field Oriented (UFO) controller, operating in an arbitrary reference frame, is applied to a CRPWM inverter. Due to its high degree of generality the UFO controller is compatible with rotor, stator and airgap flux field oriented control. The authors compare the stability regions and the steady state performance of these three types of controllers applied to the same machine. The rotor flux based controller has been selected as the basic reference. Digital simulation results are carried out to show that the performance of the complete UFO system, i.e., combined direct and indirect UFO, in non rotor flux based reference frames leads to a robust high performance drive with no dependency on machine parameters in steady state.

EPE 1991 - 44 - Session 4.11: FIELD ORIENTED CONTROL 2
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1991 - Conference > EPE 1991 - 44 - Session 4.11: FIELD ORIENTED CONTROL 2
	[return to parent folder]

	IMPROVEMENT OF ROBUSTNESS ON SPEED SENSORLESS VECTOR CONTROL OF INDUCTION MOTOR By Ichiroh Miyashita; Youichi Ohmori	[View] [Download]
Abstract: This paper discusses high-speed, high-precision, robust torque and speed control techniques for a speed sensorless induction motor based on the instantaneous flux and slip calculation. The torque control system has proved to be insensitive to primary resistance (R1) variations and entirely robust to secondary resistance (R2) variations. However, the speed control system is only insensitive to R1 and still remains sensitive to R2 variations. A new method to solve this problem, with R2 identification, is proposed, using a specified harmonic component due to rotor slotting. The real R2 value is obtained during on-line operation by correcting the nominal R2 value according to the error signal between the calculated speed and actual speed detected from the frequency of the harmonic.

	FIELD-WEAKENING WITH THE DIRECT SELF CONTROL (DSC) AS A CONTROL-SCHEME FOR HIGH POWER THREE-LEVEL GTO INVERTERS By F. Springmeier; J. K. Steinke	[View] [Download]
Abstract: For inverters in the MW-range the switching frequency of each valve is limited to 100 - 300Hz. A very good control method if working with low switching-frequencies is Direct Self Control (DSC), developed 1984 by M. Depenbrock for voltage source inverter-fed induction motors. This control algorithm directly determines the switching states of the inverter and gives an optimal characteristic for stator flux and torque control. Compared to a conventional two-level inverter, smoother waveshapes of current, flux and torque are obtained by using a three-level GTO inverter. Direct Self Control modified for application with a three-level inverter also has to allow field-weakening which is necessary when stator-frequency is above rated stator frequency of the motor. This control scheme and practical results of its application, measured at a 20KW inverter-motor test-system, are discussed in this paper.

	Low Switching Frequency High-Power lnverter Drive Based on Field-Oriented Pulsewidth Modulation By Ashwin Khambadkone; Joachim Holtz	[View] [Download]
Abstract: In megawatt rated inverter-fed induction motor drive systems, the GTO switching losses account for a considerable amount of the total losses. Hence, the switching frequency in such systems must be kept at a low value of only a few hundred Hertz. To avoid undesired torque harmonics under such operating conditions, the pulse control of the inverter is made dependent on the orientation of the rotor flux orientation of the drive machine. This method transfers a major portion of the unavoidable current distortions into the field axis where they have no influence on the machine torque. An optimal trajectory oriented control is presented which achieves low switching frequency at low torque and current harmonics and exhibits a very fast dynamic response. The performance of this method is demonstrated by measured results from a 30-kW model drive.

	A STATOR FLUX ORIENTED SPEED CONTROL OF INDUCTION MACHINE WITHOUT SPEED SENSOR By Hyung-Soo Mok; Joohn-Sheok Kim; Young-Real Kim; Min-Ho Park; Seung-Ki Sul	[View] [Download]
Abstract: This paper describes the stator flux oriented speed control strategy with the speed estimation algorithm. And the method of adapting rotor time constant variations is proposed. Since the estimation of the stator flux is independent of the leakage inductance, our scheme uses direct stator flux oriented control method. A decoupler is realized to minimize the coupling between d-axis and q-axis component of the stator currents in the stator flux reference frame. The effectiveness of the proposed system is verified by computer simulation.

	A NEW VECTOR CONTROL SCHEME FOR INVERTER-FED PERMANENT MAGNET SYNCHRONOUS MOTOR USING DSP By J. Moerschell; M. Tursini	[View] [Download]
Abstract: This paper presents a new vector control scheme for inverter-fed permanent magnet synchronous motor suitable for DSP implementation. The design of the control scheme is carried out considering the model of the motor in a stationary two-phases frame of reference. This in order to work directly with measurable currents and voltages. The electromagnetic torque and the reactive power are directly controlled by hysteresis regulators whose outputs are used to generate the command signals of the three-phase inverter. Position sensor and coordinate transformations are not needed, then the signal processing equipment is very simple and the calculation time is reduced. Experimental tests in which the proposed scheme is used to realize the control of the motor with unity power factor are shown.

	Comparison of Universal Field Oriented (UFO) Controllers in Different Reference Frames By F. Profumo; M. Pastorelli; P. Ferraris; R. W. De Doncker	[View] [Download]
Abstract: The principle of the Universal Field Oriented (UFO) controller, operating in an arbitrary reference frame, is applied to a CRPWM inverter. Due to its high degree of generality the UFO controller is compatible with rotor, stator and airgap flux field oriented control. The authors compare the stability regions and the steady state performance of these three types of controllers applied to the same machine. The rotor flux based controller has been selected as the basic reference. Digital simulation results are carried out to show that the performance of the complete UFO system, i.e., combined direct and indirect UFO, in non rotor flux based reference frames leads to a robust high performance drive with no dependency on machine parameters in steady state.