EPE Association: EPE 1989 - 41 - Dialogue Session 3.3: ADJUSTABLE SPEED DRIVES

EPE 1989 - 41 - Dialogue Session 3.3: ADJUSTABLE SPEED DRIVES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 41 - Dialogue Session 3.3: ADJUSTABLE SPEED DRIVES

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   LIMIT RATING OF AN INDUCTION MACHINE IN A VARIABLE-SPEED DRIVE
By J. J. Rousseau; J. P. Masson [View]
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Abstract: In this paper, we determine through experiment the safe-operating area of a machine in a variable speed drive. The temperature limits of the components of the motor are mainly modified by the rotation speed. We have made some measurements on a small power induction machine and we present a steady-state thermal model in order to spare experimentation time. After testing the model, we present the available torque as a function of frequency. The results show that below nominal frequencies it is necessary to use the motor with reduced features.

   FIRST, PROTOTYPE CYCLOCONVERTER FED SYNCHRONOUS MOTOR WINDING MACHINE DRIVE SYSTEM IN POLAND
By Henryk Zygmunt; Andrzej Zur; Zbigniew Mikos [View]
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Abstract: In this paper a cycloconverter fed 900 kW synchronous motor drive system is presented. This system is designed for driving a winding machine for shaft depth up to 550 m, hoisting capacity of 6 Mg and maximum speed of 6 m/s. For the purpose of system operation with high dynamic performance and excellent static characteristics over a full speed range the field-oriented control method is applied. The paper describes the synchronous motor fed system, motor and cycloconverter control system structure, an idea of motor current references calculation and a structure of current reference calculator. The results of drive system test and motor voltage, current and speed waveforms are also presented.

   PROTECTION OF AN ASYNCHRONMOTOR VOLTAGE-INVERTER DRIVE BY INTERDICTION OF THE INVERTER FIRING
By S. Halasz; M. M. El-Sayed; T. Molnar; K. Veszpremi [View]
[Download]

Abstract: The paper is dealing with investigation of the transient operation occuring during interdiction of the inverter thyristors (transisitors, GTO's) firing after motor overcurrents. The analytical calculation was carried out by neglecting the motor Ohmic resistance, the calculations were checked by accurate computer examinations. Finally the calculations were compared with measurements. Both calculations and tests were proving that after the firing prohibition of the inverter semiconductors the motor stator current - depending on the working point - is coming to an within 1-2 ms at PWM inverters and within 1-10 ms at simple (six steps) inverters. For generator operation the current is coming to an end in much greater time interval and this causes a considerable increase of the D.C. voltage of the inverter.

   INDUCTION MOTOR STATE OBSERVER WITH DYNAMIC PERFORMANCE
By S. Lorenzo; L. A. L. Nozal; J. M. Ruiz; I. Lobo [View]
[Download]

Abstract: One of the most important characteristics of a good state observer for any type of plant, must be to reflect the plant performance, both in the transient and in the steady-state response. First in this paper, we present the AC induction motor equivalent circuit, called TI, which one has the linear TORQUE-SPEED characteristics. Also we study the transient performance of the conventional state observers doing several simulations to show their very poor transient response. We develop a new rotating vectorial theory, to describe any type of transient or steady state conditions, which is applicable to any AC system with the field orientation theory. We present a new type of state observer (called Is-state observer) which describes very accurately the AC motor dynamics, comparing in several simulations its characteristics with the conventional ones. We present a full, control-Is state observer set, which gives a very accurate solution in steady-state as well as in transient conditions. Finally we present a complete simulation set to give a real feeling about the high quality of the new Is-state observer here proposed.

   SLIDING MODE CONTROL STRATAGE AND REALIZATION OF AC VARIABLE SPEED DRIVE SYSTEM
By Min-Xun Chen; Hui-Jun Huang [View]
[Download]

Abstract: This paper details an AC motor inverter-fed drive system which based on the sliding mode variable structure control strategy. The system structured with GTR-PWM inverter and controlled by the microcomputer. In the paper discussed the strategies of the sliding mode control and put forward a method that the measure of angle velocity only can judge the symbol of super surface, thereby determine the switch time and direction. As the result of the motor current exists harmonics, the paper gives a simple effect method to evalute the realtime effective value of the current at any frequency precisely and instantly. The system is examined at a 0.75 Kw AC motor, and got a satisfying dynamic performance such as rapid response, zero overshoot and robustness to the various of the motor parameter.

   ROBUST NONLINEAR CONTROL ALGORITHM FOR FAST POSITIONING IN SERVO DRIVES
By Dusan Borojevic [View]
[Download]

Abstract: The paper presents a novel, modified adaptive control algorithm for use in the position loop of servo drives. Speed loop and the drive are assumed to comprise a fast, robust, dominantly single-pole system. The algorithm is a high-gain model-reference control scheme with added resetting and anti wind-up mechanisms. The closed-loop system follows the reference model in a sliding mode fashion during the initial part of a positioning transient, while in the final part, it behaves like a linear high-gain system. This results in the robustness of a sliding mode control, with the steady state chattering avoided. The simulations for 10:1 change in drlve's moment of inertia show the small signal bandwidth practically unchanged, while the overall transient time is considerably reduced compared to conventional design.

   CONTROL OF INDUCTION MOTORS USING PHASE CURRENT FEEDBACK DERIVED FROM THE DC LINK
By T. C. Green; B. W. Williams [View]
[Download]

Abstract: A simple scalar controller for an induction machine has been implemented with a reduced sensing requirement. The technique developed allows the instantaneous line currents of an inverter supplied motor to be derived and assessed from the d.c. link. The fault current detection transducer normally present in the d.c. link of an inverter is utilized for this purpose. The derived current signals have a bandwidth limited only by the inverter switching frequency (and not the fundamental motor supply frequency) and are suitable for control purposes, particularly at low speeds. The scalar controller uses a simple estimation procedure based on the current signals to maintain a constant stator flux in steady-state. The low speed torque characteristic obtained with this drive is compared with a computer model to confirm correct operation.

   SPEED-TORQUE CHARACTERISTIC OPTIMISATION FOR SELF-COMMUTATED SYNCHRONOUS MOTORS
By M. Crivii; M. Jufer [View]
[Download]

Abstract: The self commutated synchronous motors, switched reluctance or brushless DC, are more and more often used in a wide range of power, from stepping to traction motors. In a self-commutation mode, the motor is supplied by an electronic power driver, the control of which is based on the rotor position information. One of the main problem of the self-commutation is the motor coils excitation at the correct position to develop the required torque with the best efficiency. In this purpose a direct or indirect rotor position detection and the commutation lead angle regulation are necessary. In this paper, a new torque optimisation strategy, using an indirect lead angle regulation is presented.

EPE 1989 - 41 - Dialogue Session 3.3: ADJUSTABLE SPEED DRIVES
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 41 - Dialogue Session 3.3: ADJUSTABLE SPEED DRIVES
	[return to parent folder]

	LIMIT RATING OF AN INDUCTION MACHINE IN A VARIABLE-SPEED DRIVE By J. J. Rousseau; J. P. Masson	[View] [Download]
Abstract: In this paper, we determine through experiment the safe-operating area of a machine in a variable speed drive. The temperature limits of the components of the motor are mainly modified by the rotation speed. We have made some measurements on a small power induction machine and we present a steady-state thermal model in order to spare experimentation time. After testing the model, we present the available torque as a function of frequency. The results show that below nominal frequencies it is necessary to use the motor with reduced features.

	FIRST, PROTOTYPE CYCLOCONVERTER FED SYNCHRONOUS MOTOR WINDING MACHINE DRIVE SYSTEM IN POLAND By Henryk Zygmunt; Andrzej Zur; Zbigniew Mikos	[View] [Download]
Abstract: In this paper a cycloconverter fed 900 kW synchronous motor drive system is presented. This system is designed for driving a winding machine for shaft depth up to 550 m, hoisting capacity of 6 Mg and maximum speed of 6 m/s. For the purpose of system operation with high dynamic performance and excellent static characteristics over a full speed range the field-oriented control method is applied. The paper describes the synchronous motor fed system, motor and cycloconverter control system structure, an idea of motor current references calculation and a structure of current reference calculator. The results of drive system test and motor voltage, current and speed waveforms are also presented.

	PROTECTION OF AN ASYNCHRONMOTOR VOLTAGE-INVERTER DRIVE BY INTERDICTION OF THE INVERTER FIRING By S. Halasz; M. M. El-Sayed; T. Molnar; K. Veszpremi	[View] [Download]
Abstract: The paper is dealing with investigation of the transient operation occuring during interdiction of the inverter thyristors (transisitors, GTO's) firing after motor overcurrents. The analytical calculation was carried out by neglecting the motor Ohmic resistance, the calculations were checked by accurate computer examinations. Finally the calculations were compared with measurements. Both calculations and tests were proving that after the firing prohibition of the inverter semiconductors the motor stator current - depending on the working point - is coming to an within 1-2 ms at PWM inverters and within 1-10 ms at simple (six steps) inverters. For generator operation the current is coming to an end in much greater time interval and this causes a considerable increase of the D.C. voltage of the inverter.

	INDUCTION MOTOR STATE OBSERVER WITH DYNAMIC PERFORMANCE By S. Lorenzo; L. A. L. Nozal; J. M. Ruiz; I. Lobo	[View] [Download]
Abstract: One of the most important characteristics of a good state observer for any type of plant, must be to reflect the plant performance, both in the transient and in the steady-state response. First in this paper, we present the AC induction motor equivalent circuit, called TI, which one has the linear TORQUE-SPEED characteristics. Also we study the transient performance of the conventional state observers doing several simulations to show their very poor transient response. We develop a new rotating vectorial theory, to describe any type of transient or steady state conditions, which is applicable to any AC system with the field orientation theory. We present a new type of state observer (called Is-state observer) which describes very accurately the AC motor dynamics, comparing in several simulations its characteristics with the conventional ones. We present a full, control-Is state observer set, which gives a very accurate solution in steady-state as well as in transient conditions. Finally we present a complete simulation set to give a real feeling about the high quality of the new Is-state observer here proposed.

	SLIDING MODE CONTROL STRATAGE AND REALIZATION OF AC VARIABLE SPEED DRIVE SYSTEM By Min-Xun Chen; Hui-Jun Huang	[View] [Download]
Abstract: This paper details an AC motor inverter-fed drive system which based on the sliding mode variable structure control strategy. The system structured with GTR-PWM inverter and controlled by the microcomputer. In the paper discussed the strategies of the sliding mode control and put forward a method that the measure of angle velocity only can judge the symbol of super surface, thereby determine the switch time and direction. As the result of the motor current exists harmonics, the paper gives a simple effect method to evalute the realtime effective value of the current at any frequency precisely and instantly. The system is examined at a 0.75 Kw AC motor, and got a satisfying dynamic performance such as rapid response, zero overshoot and robustness to the various of the motor parameter.

	ROBUST NONLINEAR CONTROL ALGORITHM FOR FAST POSITIONING IN SERVO DRIVES By Dusan Borojevic	[View] [Download]
Abstract: The paper presents a novel, modified adaptive control algorithm for use in the position loop of servo drives. Speed loop and the drive are assumed to comprise a fast, robust, dominantly single-pole system. The algorithm is a high-gain model-reference control scheme with added resetting and anti wind-up mechanisms. The closed-loop system follows the reference model in a sliding mode fashion during the initial part of a positioning transient, while in the final part, it behaves like a linear high-gain system. This results in the robustness of a sliding mode control, with the steady state chattering avoided. The simulations for 10:1 change in drlve's moment of inertia show the small signal bandwidth practically unchanged, while the overall transient time is considerably reduced compared to conventional design.

	CONTROL OF INDUCTION MOTORS USING PHASE CURRENT FEEDBACK DERIVED FROM THE DC LINK By T. C. Green; B. W. Williams	[View] [Download]
Abstract: A simple scalar controller for an induction machine has been implemented with a reduced sensing requirement. The technique developed allows the instantaneous line currents of an inverter supplied motor to be derived and assessed from the d.c. link. The fault current detection transducer normally present in the d.c. link of an inverter is utilized for this purpose. The derived current signals have a bandwidth limited only by the inverter switching frequency (and not the fundamental motor supply frequency) and are suitable for control purposes, particularly at low speeds. The scalar controller uses a simple estimation procedure based on the current signals to maintain a constant stator flux in steady-state. The low speed torque characteristic obtained with this drive is compared with a computer model to confirm correct operation.

	SPEED-TORQUE CHARACTERISTIC OPTIMISATION FOR SELF-COMMUTATED SYNCHRONOUS MOTORS By M. Crivii; M. Jufer	[View] [Download]
Abstract: The self commutated synchronous motors, switched reluctance or brushless DC, are more and more often used in a wide range of power, from stepping to traction motors. In a self-commutation mode, the motor is supplied by an electronic power driver, the control of which is based on the rotor position information. One of the main problem of the self-commutation is the motor coils excitation at the correct position to develop the required torque with the best efficiency. In this purpose a direct or indirect rotor position detection and the commutation lead angle regulation are necessary. In this paper, a new torque optimisation strategy, using an indirect lead angle regulation is presented.