EPE Association: EPE 1985 - 16 - Lecture Session 3.02: MICROPROCESSOR CONTROL FOR AC DRIVES (II)

EPE 1985 - 16 - Lecture Session 3.02: MICROPROCESSOR CONTROL FOR AC DRIVES (II)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1985 - Conference > EPE 1985 - 16 - Lecture Session 3.02: MICROPROCESSOR CONTROL FOR AC DRIVES (II)

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   A MICROPROCESSOR-BASED CURRENT CONTROLLER WITH AN INTERNAL CURRENT RATE LOOP FOR MOTOR DRIVES
By T. Ohmae; T. Matsuda; R. Masaki; K. Saito [View]
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Abstract: A new current control method is described which is suitable for a microprocessor-based speed regulator of motor drives. The method achieves fast response and high accuracy performance by using a major current loop and an internal current rate loop. The former is used to control precisely the mean value of the motor current by employing a current feedback signal obtained from a smoothing filter of the rippled current. The latter loop is used to stabilize the major loop with a high gain and to limit the variation rate of the motor current by employing the current feedback signal obtained from the instantaneous current without time delay. A current controller using a microprocessor was trial manufactured and tested with a thyristor converter driven dc motor. It was found that, fast controlled current response can be obtained even with a relatively long sampling period.

   MICROPROCESSOR-CONTROLLED THREE-PHASE MOTORS WITH HIGH-RESOLUTION DIGITAL PULSE WIDTH MODULATOR FOR HIGH PULSE FREQUENCIES
By B. Orlik; H. Weh [View]
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Abstract: If a microcomputer is employed to provide control signal processing in three-phase drives, than it is in the interest of reliability, that the pulse width modulation is likewise performed completely digitally. The rapid development of gate arrays provides a cost-effective means of realizing the digital pulse width modulator in hardware, as a peripheral circuit to the microcomputer. The modulator circuit, discribed in the following report functions completely digitally and thus offers favourable prerequisites for a gate array implementation. The maximum operating frequency is 20 MHz. This allows a high level of pulse pattern quantisation even for high converter frequencies. The harmonic oscillation components of the armature currents are effected by the ratio of the motor frequency to the sampling frequency of the microcomputer and by the way in which the microcomputer and the pulse width modulator are coupled. In order to achieve digital signal processing as far as possible, a poorly digital circuit for interlocking the converter bridge arms is also given. The interlock circuit is also capable of integration on a gate array. The design of the interlock circuit and the pulse width modulator as customized digital circuits allows the circuit outlay to be considerably reduced by comparison with conventional realizations. At the same time, enhanced reliability and easy installation can be anticipated.

   A MICROPROCESSOR-BASED STATE OBSERVER FOR THE FEEDBACK CONTROL OF INDUCTION MOTOR DRIVES
By A. Bellini; G. Figalli; G. Ulivi [View]
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Abstract: The paper takes into consideration the reconstruction of the stator and rotor flux of the induction machine on the basis of its directly measurable variables. To this aim, a model of a reduced order observer is obtained and the problems connected with its implementation on a microcomputer-based system are analyzed. Several tests effected by simulation have shown a good rejection both to the parametric variations and to the errors introduced by the implementation.

   A CONCEPTION FOR A SENSORLESS SPEED CONTROL OF THE SQUIRREL CAGE INDUCTION MOTOR
By M. Beck; D. Naunin [View]
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Abstract: For the sensorless speed control of a squirrel cage induction motor a new method for the slip-frequency calculation will be presented. A relation is derived that permits to calculate the electrical rotor frequency directly from the phase angle between the stator voltage and current. The practical realization needs a stator voltage which provides harmonic elimination with a predetermined zero crossing of the fundamental, and a filtering procedure for the zero detection of the stator current. The essential characteristics of the utilized PWM method as well as the filter algorithm are demonstrated and the application of the slip-frequency calculation in a control scheme is discussed.

   MICROPROCESSOR-CONTROLLED SYNCHRONOUS SERVO DRIVE
By H.-H. Letas [View]
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Abstract: At present electrical servo-drives are mostly realised by using DC servo-motors with permanent excitation or separate field windings. In order to eliminate the commutator and to achieve a compact design, a permanent magnet sychronous motor with rare earth magnet excitation has been developed. The 1.2 kW synchronous servo drive described performs a speed step of 2000 rpm in 7 milliseconds at 6 times rated current. In the field weakening range the speed can be raised up to 8000 rpm. The power supply consists of a high frequency transistor inverter. The speed and position control of the drive is performed by a double-microprocessor system based on the INTEL 8086 employing rotor coordinates. The sampling rate of 3.2 kHz requires a high resolution speed and position sensing. The resolution of an incremental optical sensor with 1024 cycles per rev. was greatly improved up to 260 000 / rev. by evaluating the waveform of the nearly sinusoidal sensor outputs.

EPE 1985 - 16 - Lecture Session 3.02: MICROPROCESSOR CONTROL FOR AC DRIVES (II)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1985 - Conference > EPE 1985 - 16 - Lecture Session 3.02: MICROPROCESSOR CONTROL FOR AC DRIVES (II)
	[return to parent folder]

	A MICROPROCESSOR-BASED CURRENT CONTROLLER WITH AN INTERNAL CURRENT RATE LOOP FOR MOTOR DRIVES By T. Ohmae; T. Matsuda; R. Masaki; K. Saito	[View] [Download]
Abstract: A new current control method is described which is suitable for a microprocessor-based speed regulator of motor drives. The method achieves fast response and high accuracy performance by using a major current loop and an internal current rate loop. The former is used to control precisely the mean value of the motor current by employing a current feedback signal obtained from a smoothing filter of the rippled current. The latter loop is used to stabilize the major loop with a high gain and to limit the variation rate of the motor current by employing the current feedback signal obtained from the instantaneous current without time delay. A current controller using a microprocessor was trial manufactured and tested with a thyristor converter driven dc motor. It was found that, fast controlled current response can be obtained even with a relatively long sampling period.

	MICROPROCESSOR-CONTROLLED THREE-PHASE MOTORS WITH HIGH-RESOLUTION DIGITAL PULSE WIDTH MODULATOR FOR HIGH PULSE FREQUENCIES By B. Orlik; H. Weh	[View] [Download]
Abstract: If a microcomputer is employed to provide control signal processing in three-phase drives, than it is in the interest of reliability, that the pulse width modulation is likewise performed completely digitally. The rapid development of gate arrays provides a cost-effective means of realizing the digital pulse width modulator in hardware, as a peripheral circuit to the microcomputer. The modulator circuit, discribed in the following report functions completely digitally and thus offers favourable prerequisites for a gate array implementation. The maximum operating frequency is 20 MHz. This allows a high level of pulse pattern quantisation even for high converter frequencies. The harmonic oscillation components of the armature currents are effected by the ratio of the motor frequency to the sampling frequency of the microcomputer and by the way in which the microcomputer and the pulse width modulator are coupled. In order to achieve digital signal processing as far as possible, a poorly digital circuit for interlocking the converter bridge arms is also given. The interlock circuit is also capable of integration on a gate array. The design of the interlock circuit and the pulse width modulator as customized digital circuits allows the circuit outlay to be considerably reduced by comparison with conventional realizations. At the same time, enhanced reliability and easy installation can be anticipated.

	A MICROPROCESSOR-BASED STATE OBSERVER FOR THE FEEDBACK CONTROL OF INDUCTION MOTOR DRIVES By A. Bellini; G. Figalli; G. Ulivi	[View] [Download]
Abstract: The paper takes into consideration the reconstruction of the stator and rotor flux of the induction machine on the basis of its directly measurable variables. To this aim, a model of a reduced order observer is obtained and the problems connected with its implementation on a microcomputer-based system are analyzed. Several tests effected by simulation have shown a good rejection both to the parametric variations and to the errors introduced by the implementation.

	A CONCEPTION FOR A SENSORLESS SPEED CONTROL OF THE SQUIRREL CAGE INDUCTION MOTOR By M. Beck; D. Naunin	[View] [Download]
Abstract: For the sensorless speed control of a squirrel cage induction motor a new method for the slip-frequency calculation will be presented. A relation is derived that permits to calculate the electrical rotor frequency directly from the phase angle between the stator voltage and current. The practical realization needs a stator voltage which provides harmonic elimination with a predetermined zero crossing of the fundamental, and a filtering procedure for the zero detection of the stator current. The essential characteristics of the utilized PWM method as well as the filter algorithm are demonstrated and the application of the slip-frequency calculation in a control scheme is discussed.

	MICROPROCESSOR-CONTROLLED SYNCHRONOUS SERVO DRIVE By H.-H. Letas	[View] [Download]
Abstract: At present electrical servo-drives are mostly realised by using DC servo-motors with permanent excitation or separate field windings. In order to eliminate the commutator and to achieve a compact design, a permanent magnet sychronous motor with rare earth magnet excitation has been developed. The 1.2 kW synchronous servo drive described performs a speed step of 2000 rpm in 7 milliseconds at 6 times rated current. In the field weakening range the speed can be raised up to 8000 rpm. The power supply consists of a high frequency transistor inverter. The speed and position control of the drive is performed by a double-microprocessor system based on the INTEL 8086 employing rotor coordinates. The sampling rate of 3.2 kHz requires a high resolution speed and position sensing. The resolution of an incremental optical sensor with 1024 cycles per rev. was greatly improved up to 260 000 / rev. by evaluating the waveform of the nearly sinusoidal sensor outputs.