EPE Association: EPE 1993 - 34 - Dialogue Session DS1.10: DRIVES: MODELLING, SIMULATION AND GENERAL ASPECTS (Part I)

EPE 1993 - 34 - Dialogue Session DS1.10: DRIVES: MODELLING, SIMULATION AND GENERAL ASPECTS (Part I)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 34 - Dialogue Session DS1.10: DRIVES: MODELLING, SIMULATION AND GENERAL ASPECTS (Part I)

   [return to parent folder]

   A VARIABLE SPEED DRIVE CIRCUIT TOPOLOGY FOR FEEDING A 3-PHASE INVERTER BRIDGE WITH A COMBINED CURRENT AND VOLTAGE DC LINK
By John C. Salmon [View]
[Download]

Abstract: This paper describes the operation of a 3-phase drive that supplies a 3-phase inverter bridge with a combined current and voltage dc link. During steady state conditions, the dc-rail voltage is controlled at levels above the rectified supply voltage. The high switching frequencies of the inverter bridge can be used to lower the size of the dc-link capacitors and inductors. During output short-circuit fault conditions, the dc-link capacitor can be automatically disconnected and the rate of rise of fault currents can be restricted by the dc-link inductor. Protection is obtained against short circuit faults such as line-line and line to supply neutral faults. Simulation results are used to illustrate the drive operation.

   THREE-PHASE EQUIVALENT CIRCUITS FOR NETWORK SIMULATION OF INDUCTION MACHINES
By M. J. Hoeijmakers; P. J. van Duijsen [View]
[Download]

Abstract: For the investigation of converters, network simulation programs may be skilful tools. On the other hand, indudion machines are mostly described by differential equations. The combination of a converter and an induction machine may also be investigated in a network simulation program. However, in this case the rotor position angle, dependency of the mutual inductances between stator and rotor results in a lot of computation time. In this paper, three-phase equivalent circuits for induction machines (with accessible star connection point) are derived in which the rotor angle dependency is eliminated. Starting from a general description of an induction machine, the rotor angle dependency is eliminated by transforming (rotating) the rotor variables from the rotor to the stator reference system. Next, the circuit is simplified by referring the rotor quantities to the stator. At the end, this circuit is simplified for the case the star connection point is not used.

   REMEDIAL STRATEGY FOR INVERTER-INDUCTION MACHINE SYSTEM FAULTS USING TWO-PHASE OPERATION
By T. Elch-Heb; J. P. Hautier [View]
[Download]

Abstract: In this paper the authors present an optimal remedial strategy for Inverter - Three phase induction machine system drive faults. Remedial strategy can be a single-phase operation when neutral point of star coupled induction machine is not connected, and is a two-phase operation when neutral point is connected to dc Source Voltage of a Current Controlled lnverter. In this case ripple component, which is unavoidable in single-phase operation, can be supressed when current references are pi/3 shifted. This optimal two-phase operation mode can be used to perform field-oriented control as in three-phase operation. Obtained performances with two-phase operation are then similar to those of three-phase mode but with currents magnitude V3 more important.

   STEADY-STATE ANALYSIS AND SAMPLED DATA MODELING OF AC POWER CONVERTERS USING THE MNA METHOD
By P. J. van Duijsen [View]
[Download]

Abstract: The Steady-state MNA method establishes steady-state analysis of AC power converters which contain linear elements. This method is easier to implement than state equations and allows the calculation of a transition matrix without approximation. The MNA method offers equations with a better observability than conventional state space steady-state modeling. The steady-state MNA method is also suitable for sampled data modeling.

   THE ANALYSIS OF AC/DC CONVERTER HARMONICS IN TRANSIENT STATE
By V. A. Katic; D. Dapcevic; V. S. Vuckovic [View]
[Download]

Abstract: Voltage and current network harmonics generated during operation of the DC motor drive supplied by AC/DC converters are analyzed. Two kinds of current controlled AC/DC converters are considered: 1. line-commutated and 2. force commutated (PWM rectifiers). The full regulation loop is included. Transient states harmonics during speed and torque change are considered and compared with ones in steady-state. Results show their significant increase, specially during start of DC drive. They exceed both short-term and long-term limits defined by existing standards or recommendations. Therefore harmonics in transient states must be taken into account when AC side filter is designed, particularly in cases of large size DC drives, where transient intervals are significant.

   NEW PWM INVERTER MODELLING METHOD APPLIED TO THE DESIGN OF A CURRENT CONTROLLER FOR THREE-PHASE HIGH PERFORMANCE PM SYNCHRONOUS ACTUATOR
By E. Matagne [View]
[Download]

Abstract: Control systems of PWM inverter fed PM synchronous motor usually include analog current loops which control the motor currents according to reference values generated by a main controller. For high speed actuators such loops must have a high open loop gain up to relatively high frequencies. lf, in order to limit commutation losses, the inverter PWM frequency cannot be increased accordingly, the current loop gain may not be negligeable at half of the modulation frequency. The stability analysis of these loops requires then an adequate modelling of the PWM inverter. We have recently presented such a model tor a single phase system. The paper extends this model to three phase systems and presents its application to the synthesis of the current loops of a high speed motor designed tor aeronautics application (in the frame of an EEC Brite Euram program). Experiments show accurate current control even for extreme acceleration condition (0 to 13000 rpm in 30 ms).

   SIMULATION OF CONVERTER - SYNCHRONOUS MACHINE DRIVES IN NORMAL AND FAULT OPERATION
By M. Ronkowski; K. Iwan; R. Szczesny [View]
[Download]

Abstract: A multiport transient equivalent circuit models of synchronous motors, applicable in simulation of converter drive systems, are presented. The proposed circuits exhibit networks with the same number of external terminals as the motor and model the machine behaviour directly in terms of the stator and/or rotor and mechanical variables as well. The main advantage of the approach is the ease of describing the system in terms of its topology. Thus, different control strategies for normal and fault operation of any connverter - synchronous machine drives can be investigated. To determine the transient stator current, torque and rotor velocity for any desired supply voltage, frequency and load, the global converter-synchronous motor circuit is transformed into a sequence of dc analyses of resistive networks upon replacing each energy storage elements (inductances, rotor inertia) by a preselected implicit numerical-integration algorithm. The approach is demonstrated using a 3-phase synchronous machine supplied by a voltage source inverter. The simulation results prove that the proposed approach can be recommended for CAD programs.

   A NEW CONCEPT IN MODULAR MOTOR DRIVE SYSTEMS
By D. Richards [View]
[Download]

Abstract: This paper describes a comprehensive drive system to cover all the needs of the variable speed drives market at higher power levels (LV up to 575V ac supply). lts adaptability stems from its modular approach; allowing the use of prograrnmable or alternative control sources by means of a standardised interface, to the option of a variety of power stages. These easily removable stages range from simple rectitiers, through DC thyristor output stages, to complex inverter units using input and output bridges based on IGBT's. Higher power requirements are accommodated by paralleling smaller units mounted in a "rack" arrangement. The system has also been designed to allow the use of common dc link schemes: a growing need in multiple drive work utilising inverters. An important advantage of the system is the ease by which new developments in power devices may be incorporated with a minimum of disruption to the overall design. The original concepts are discussed, and examples of the applications given.

   SYSTEM DESIGN ISSUES FOR RESONANT DC LINK INVERTER BASED DRIVES
By C. Chen; G. A. Luckjiff; G. Venkataramanan; D. M. Divan [View]
[Download]

Abstract: This paper proposes an approach to integrate the resonant DC link inverter with a soft switching boost rectifier stage. Several advantages accrue from this arrangement on the system level including: robust performance during voltage sag conditions, improved line current THD and input power factor, and reduced dc bus capacitance requirements. Furthermore, as compared to the conventional PWM-VSI, the low frequency ripple current can be reduced. This paper inculdes analytical and experimental results.

   SERIES RESONANT DC LINK DUAL CONVERTER AS A DC MOTOR DRIVE
By M. Yoshida; H. Soebagia; Y. Murai; T. A. Lipo [View]
[Download]

Abstract: This paper presents the methods of DC motor drive control. The performances of those methods (phase-control method, resonant full and dual bridge methods) are investigated and compared through digital simulation. A series resonant DC link dual converter as a DC motor drive is proposed to obtain smooth ripple current and fast response utilizing high frequency resonance. The proposed system generates resonant current pulses, switching is done at zero current instants, and so switching losses are reduced to a minimal value. In this system, the motor current can be operated in both forward and reverse direction and also in zero current region in which previous single type converter was hard to work. The improvement of input power factor and elimination of higher harmonics content can be achieved dramatically by implemented input converter control.

   ANALYSIS AND MODELING OF FIVE PHASE CONVERTERS FOR ADJUSTABLE SPEED DRIVE APPLICATIONS
By H. A. Toliyat; M. M. Rahimian; T. A. Lipo [View]
[Download]

Abstract: Mathematical models based on complex voltage vectors for the theoretical studies of five phase voltage source inverters and five phase PWM inverters are presented. Complex vector representation is employed to help in visualizing the current regulation similar to the three phase systems. A dq model based on transformation theory is presented for five phase induction machines. Finally a detail implementation of an indirect type five phase field orientation control including the hysteresis type of PWM current regulator is described.

   A FLEXIBLE MICRO-CONTROLLER BASED CHOPPER DRIVING A PERMANENT MAGNET DC MOTOR
By J. Nicolai; T. Castagnet [View]
[Download]

Abstract: Micro-controllers are used more and more in motor drives, most commonly to turn on and off the motor, or to control the conduction angle of a triac, associated with a universal motor. In this paper, the universal motor is replaced by a permanent magnet DC motor, which offers the advantage of yielding a high power in a small volume. The variable speed drive is supplied from the rectified mains voltage, and consists of a chopper driven by a PWM signal generated by the micro-controller. The micro-controller measures the DC supply voltage and adjusts the PWM duty cycle accordingly, which has the primary effect of regulating the motor voltage against mains and load variations, which in turn adjusts the motor speed, and the secondary effect of reducing the motor current ripple, thus improving motor efficiency and copper losses.This drive also implements a software power limitation, which avoids motor overheating in case of excessive loading, and costs only a few discrete components. Software flexibility allows to easily modify drive parameters such as maximum power, time constants, etc ... The drive principle and practical results are given.

   QUANTIFYING THE MODEL VARIATION DUE TO CHANGES IN DUTY CYCLE OF DC/DC CONVERTERS
By A. Pagel; M. D. McCulloch; C. F. Landy [View]
[Download]

Abstract: A nonlinear discrete-time model of the Buck-Boost converter is linearised to obtain a linear discrete-time model. If the duty cycle of the Buck-Boost converter is changed, then a different linearised model is obtained. These linearised models can then be used to quantify the variation in the dynamics of the Buck-Boost converter with changing duty cycle. This analysis is an important step in the design of controllers based on Qualitative Feedback Theory (QFT). These controllers can be designed to give the required closed-loop operation and stability for all operating conditions. Even though a simple circuit is used this method is suitable for more complicated switching circuits. It is also shown that parasitic elements are adequately accounted for.

   CONSIDERATIONS ABOUT SOME IMPLEMENTATIONS OF DRIVES CONSISTING OF AC-MOTORS AND VARIOUS CURRENT SOURCE INVERTERS PARTICULARLY AN ANALYTICAL DERIVATION OF A T...
By J. Bonal; A. C. Wiart [View]
[Download]

Abstract: Analytical study of some implementations consisting of AC-motors and various current source inverters (dual source, PWM chopping, capacitor filter). It is shown that with a well chosen time origin the vectors representing the fundamental and the harmonic currents from the inverter are vectors having the same direction then enabling a very simple analytical torque ripple formula to be derived. In particular it is shown that the torque ripple is not directly dependent on the bulk of the harmonic currents. In fact the current vectors must be examined by pairs. Those of a same pair produce torque pulsating at the same frequency which add or substract to each other depending on their phase shift (vectorial sum). Examples are given for some specific schemes (such as dual current source inverter, PWM current source inverter, dual CSl+capacitor filter) as well as calculation of electrical resonance frequency and the filtering efficiency in relation to it.

EPE 1993 - 34 - Dialogue Session DS1.10: DRIVES: MODELLING, SIMULATION AND GENERAL ASPECTS (Part I)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1993 - Conference > EPE 1993 - 34 - Dialogue Session DS1.10: DRIVES: MODELLING, SIMULATION AND GENERAL ASPECTS (Part I)
	[return to parent folder]

	A VARIABLE SPEED DRIVE CIRCUIT TOPOLOGY FOR FEEDING A 3-PHASE INVERTER BRIDGE WITH A COMBINED CURRENT AND VOLTAGE DC LINK By John C. Salmon	[View] [Download]
Abstract: This paper describes the operation of a 3-phase drive that supplies a 3-phase inverter bridge with a combined current and voltage dc link. During steady state conditions, the dc-rail voltage is controlled at levels above the rectified supply voltage. The high switching frequencies of the inverter bridge can be used to lower the size of the dc-link capacitors and inductors. During output short-circuit fault conditions, the dc-link capacitor can be automatically disconnected and the rate of rise of fault currents can be restricted by the dc-link inductor. Protection is obtained against short circuit faults such as line-line and line to supply neutral faults. Simulation results are used to illustrate the drive operation.

	THREE-PHASE EQUIVALENT CIRCUITS FOR NETWORK SIMULATION OF INDUCTION MACHINES By M. J. Hoeijmakers; P. J. van Duijsen	[View] [Download]
Abstract: For the investigation of converters, network simulation programs may be skilful tools. On the other hand, indudion machines are mostly described by differential equations. The combination of a converter and an induction machine may also be investigated in a network simulation program. However, in this case the rotor position angle, dependency of the mutual inductances between stator and rotor results in a lot of computation time. In this paper, three-phase equivalent circuits for induction machines (with accessible star connection point) are derived in which the rotor angle dependency is eliminated. Starting from a general description of an induction machine, the rotor angle dependency is eliminated by transforming (rotating) the rotor variables from the rotor to the stator reference system. Next, the circuit is simplified by referring the rotor quantities to the stator. At the end, this circuit is simplified for the case the star connection point is not used.

	REMEDIAL STRATEGY FOR INVERTER-INDUCTION MACHINE SYSTEM FAULTS USING TWO-PHASE OPERATION By T. Elch-Heb; J. P. Hautier	[View] [Download]
Abstract: In this paper the authors present an optimal remedial strategy for Inverter - Three phase induction machine system drive faults. Remedial strategy can be a single-phase operation when neutral point of star coupled induction machine is not connected, and is a two-phase operation when neutral point is connected to dc Source Voltage of a Current Controlled lnverter. In this case ripple component, which is unavoidable in single-phase operation, can be supressed when current references are pi/3 shifted. This optimal two-phase operation mode can be used to perform field-oriented control as in three-phase operation. Obtained performances with two-phase operation are then similar to those of three-phase mode but with currents magnitude V3 more important.

	STEADY-STATE ANALYSIS AND SAMPLED DATA MODELING OF AC POWER CONVERTERS USING THE MNA METHOD By P. J. van Duijsen	[View] [Download]
Abstract: The Steady-state MNA method establishes steady-state analysis of AC power converters which contain linear elements. This method is easier to implement than state equations and allows the calculation of a transition matrix without approximation. The MNA method offers equations with a better observability than conventional state space steady-state modeling. The steady-state MNA method is also suitable for sampled data modeling.

	THE ANALYSIS OF AC/DC CONVERTER HARMONICS IN TRANSIENT STATE By V. A. Katic; D. Dapcevic; V. S. Vuckovic	[View] [Download]
Abstract: Voltage and current network harmonics generated during operation of the DC motor drive supplied by AC/DC converters are analyzed. Two kinds of current controlled AC/DC converters are considered: 1. line-commutated and 2. force commutated (PWM rectifiers). The full regulation loop is included. Transient states harmonics during speed and torque change are considered and compared with ones in steady-state. Results show their significant increase, specially during start of DC drive. They exceed both short-term and long-term limits defined by existing standards or recommendations. Therefore harmonics in transient states must be taken into account when AC side filter is designed, particularly in cases of large size DC drives, where transient intervals are significant.

	NEW PWM INVERTER MODELLING METHOD APPLIED TO THE DESIGN OF A CURRENT CONTROLLER FOR THREE-PHASE HIGH PERFORMANCE PM SYNCHRONOUS ACTUATOR By E. Matagne	[View] [Download]
Abstract: Control systems of PWM inverter fed PM synchronous motor usually include analog current loops which control the motor currents according to reference values generated by a main controller. For high speed actuators such loops must have a high open loop gain up to relatively high frequencies. lf, in order to limit commutation losses, the inverter PWM frequency cannot be increased accordingly, the current loop gain may not be negligeable at half of the modulation frequency. The stability analysis of these loops requires then an adequate modelling of the PWM inverter. We have recently presented such a model tor a single phase system. The paper extends this model to three phase systems and presents its application to the synthesis of the current loops of a high speed motor designed tor aeronautics application (in the frame of an EEC Brite Euram program). Experiments show accurate current control even for extreme acceleration condition (0 to 13000 rpm in 30 ms).

	SIMULATION OF CONVERTER - SYNCHRONOUS MACHINE DRIVES IN NORMAL AND FAULT OPERATION By M. Ronkowski; K. Iwan; R. Szczesny	[View] [Download]
Abstract: A multiport transient equivalent circuit models of synchronous motors, applicable in simulation of converter drive systems, are presented. The proposed circuits exhibit networks with the same number of external terminals as the motor and model the machine behaviour directly in terms of the stator and/or rotor and mechanical variables as well. The main advantage of the approach is the ease of describing the system in terms of its topology. Thus, different control strategies for normal and fault operation of any connverter - synchronous machine drives can be investigated. To determine the transient stator current, torque and rotor velocity for any desired supply voltage, frequency and load, the global converter-synchronous motor circuit is transformed into a sequence of dc analyses of resistive networks upon replacing each energy storage elements (inductances, rotor inertia) by a preselected implicit numerical-integration algorithm. The approach is demonstrated using a 3-phase synchronous machine supplied by a voltage source inverter. The simulation results prove that the proposed approach can be recommended for CAD programs.

	A NEW CONCEPT IN MODULAR MOTOR DRIVE SYSTEMS By D. Richards	[View] [Download]
Abstract: This paper describes a comprehensive drive system to cover all the needs of the variable speed drives market at higher power levels (LV up to 575V ac supply). lts adaptability stems from its modular approach; allowing the use of prograrnmable or alternative control sources by means of a standardised interface, to the option of a variety of power stages. These easily removable stages range from simple rectitiers, through DC thyristor output stages, to complex inverter units using input and output bridges based on IGBT's. Higher power requirements are accommodated by paralleling smaller units mounted in a "rack" arrangement. The system has also been designed to allow the use of common dc link schemes: a growing need in multiple drive work utilising inverters. An important advantage of the system is the ease by which new developments in power devices may be incorporated with a minimum of disruption to the overall design. The original concepts are discussed, and examples of the applications given.

	SYSTEM DESIGN ISSUES FOR RESONANT DC LINK INVERTER BASED DRIVES By C. Chen; G. A. Luckjiff; G. Venkataramanan; D. M. Divan	[View] [Download]
Abstract: This paper proposes an approach to integrate the resonant DC link inverter with a soft switching boost rectifier stage. Several advantages accrue from this arrangement on the system level including: robust performance during voltage sag conditions, improved line current THD and input power factor, and reduced dc bus capacitance requirements. Furthermore, as compared to the conventional PWM-VSI, the low frequency ripple current can be reduced. This paper inculdes analytical and experimental results.

	SERIES RESONANT DC LINK DUAL CONVERTER AS A DC MOTOR DRIVE By M. Yoshida; H. Soebagia; Y. Murai; T. A. Lipo	[View] [Download]
Abstract: This paper presents the methods of DC motor drive control. The performances of those methods (phase-control method, resonant full and dual bridge methods) are investigated and compared through digital simulation. A series resonant DC link dual converter as a DC motor drive is proposed to obtain smooth ripple current and fast response utilizing high frequency resonance. The proposed system generates resonant current pulses, switching is done at zero current instants, and so switching losses are reduced to a minimal value. In this system, the motor current can be operated in both forward and reverse direction and also in zero current region in which previous single type converter was hard to work. The improvement of input power factor and elimination of higher harmonics content can be achieved dramatically by implemented input converter control.

	ANALYSIS AND MODELING OF FIVE PHASE CONVERTERS FOR ADJUSTABLE SPEED DRIVE APPLICATIONS By H. A. Toliyat; M. M. Rahimian; T. A. Lipo	[View] [Download]
Abstract: Mathematical models based on complex voltage vectors for the theoretical studies of five phase voltage source inverters and five phase PWM inverters are presented. Complex vector representation is employed to help in visualizing the current regulation similar to the three phase systems. A dq model based on transformation theory is presented for five phase induction machines. Finally a detail implementation of an indirect type five phase field orientation control including the hysteresis type of PWM current regulator is described.

	A FLEXIBLE MICRO-CONTROLLER BASED CHOPPER DRIVING A PERMANENT MAGNET DC MOTOR By J. Nicolai; T. Castagnet	[View] [Download]
Abstract: Micro-controllers are used more and more in motor drives, most commonly to turn on and off the motor, or to control the conduction angle of a triac, associated with a universal motor. In this paper, the universal motor is replaced by a permanent magnet DC motor, which offers the advantage of yielding a high power in a small volume. The variable speed drive is supplied from the rectified mains voltage, and consists of a chopper driven by a PWM signal generated by the micro-controller. The micro-controller measures the DC supply voltage and adjusts the PWM duty cycle accordingly, which has the primary effect of regulating the motor voltage against mains and load variations, which in turn adjusts the motor speed, and the secondary effect of reducing the motor current ripple, thus improving motor efficiency and copper losses.This drive also implements a software power limitation, which avoids motor overheating in case of excessive loading, and costs only a few discrete components. Software flexibility allows to easily modify drive parameters such as maximum power, time constants, etc ... The drive principle and practical results are given.

	QUANTIFYING THE MODEL VARIATION DUE TO CHANGES IN DUTY CYCLE OF DC/DC CONVERTERS By A. Pagel; M. D. McCulloch; C. F. Landy	[View] [Download]
Abstract: A nonlinear discrete-time model of the Buck-Boost converter is linearised to obtain a linear discrete-time model. If the duty cycle of the Buck-Boost converter is changed, then a different linearised model is obtained. These linearised models can then be used to quantify the variation in the dynamics of the Buck-Boost converter with changing duty cycle. This analysis is an important step in the design of controllers based on Qualitative Feedback Theory (QFT). These controllers can be designed to give the required closed-loop operation and stability for all operating conditions. Even though a simple circuit is used this method is suitable for more complicated switching circuits. It is also shown that parasitic elements are adequately accounted for.

	CONSIDERATIONS ABOUT SOME IMPLEMENTATIONS OF DRIVES CONSISTING OF AC-MOTORS AND VARIOUS CURRENT SOURCE INVERTERS PARTICULARLY AN ANALYTICAL DERIVATION OF A T... By J. Bonal; A. C. Wiart	[View] [Download]
Abstract: Analytical study of some implementations consisting of AC-motors and various current source inverters (dual source, PWM chopping, capacitor filter). It is shown that with a well chosen time origin the vectors representing the fundamental and the harmonic currents from the inverter are vectors having the same direction then enabling a very simple analytical torque ripple formula to be derived. In particular it is shown that the torque ripple is not directly dependent on the bulk of the harmonic currents. In fact the current vectors must be examined by pairs. Those of a same pair produce torque pulsating at the same frequency which add or substract to each other depending on their phase shift (vectorial sum). Examples are given for some specific schemes (such as dual current source inverter, PWM current source inverter, dual CSl+capacitor filter) as well as calculation of electrical resonance frequency and the filtering efficiency in relation to it.