EPE Association: EPE 1989 - 35 - Dialogue Session 2.2: CONVERTERS AND INVERTERS

EPE 1989 - 35 - Dialogue Session 2.2: CONVERTERS AND INVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 35 - Dialogue Session 2.2: CONVERTERS AND INVERTERS

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   AN ENERGY CONVERSION SYSTEM FOR AN IMPLANTABLE ARTIFICIAL HEART USING SIRETS
By Toshi Hiro Nishimura; Masao Saito; Leo Lorenz [View]
[Download]

Abstract: Developing in power electronics and other advanced electronic technology, a novel trends in the techniques for internal organs such as an implantable artificial heart system is arising. It comes not only from the medical electronics but also from the techniques of a high frequency power conversion using resonant converters. This paper describes the energy conversion method for implanted artificial heart using a nobel resonant converter with SIRET and artificial heart driven system.

   LINE SIDE BEHAVIOUR OF UNCONTROLLED RECTIFIER BRIDGES WITH CAPACITIVE DC SMOOTHING
By M. Grötzbach; B. Draxler [View]
[Download]

Abstract: Small power rectifier bridges with capacitive dc smoothing work generally with a discontinuous dc current. This leads to significant deviations in the spectrum of the line harmonics compared with the known values of a good dc current smoothing. Starting from the differential and switching equations at the dc side, an analytical based direct solution of the steady state problem is proposed via difference equations. The calculation of the unknown switching points is carried out numerically due to the analytical effort. The line current can easily be obtained from the time behaviour of the dc current and with the help of a FFT-standard routine the associated spectrum is evaluated. Circuit data line impedance and dc capacitor as well as the operating point given by the dc output current are used as parameters. The results show the influence of these parameters on the line harmonics in amplitude and phase as well as the behaviour of the fundamental harmonic content and the displacement factor.

   SMALL VOLTAGE FLUCTUATIONS BY THE MANAGEMENT OF SHORT MULTICYCLE CONTROL
By R. Kersten [View]
[Download]

Abstract: The electric power control of thermal houshold appliances must be brought into accord with IEC 555 (low voltage fluctuations, harmonics and direct currents) which is difficult for halogen heaters because of their high starting currents. A computational analysis was made including the thermal time behaviour of incandescent lamps, their dynamical electric loads and their influence on the flickermeter output. A solution is presented using three triacs for the synchronous multicycle control of two halogen lamps. Besides the well known basic power steps in series, diodes antiparallel, and parallel the time management of half wave control enables additional power steps between with low voltage fluctuations and fundamental frequencies of 16 2/3 Hz. As a result quasicontinuous control is possible between 5% and full power (2-3 kW).

   COMPARATIVE ANALYSIS OF HIGH CURRENT COMPONENTS IN PWM CONTROLLED CONVERTER TOPOLOGIES QUALIFIED FOR HIGH OUTPUT POWER AND LOW OUTPUT VOLTAGE
By L. Heinemann; N. Fröhleke [View]
[Download]

Abstract: A comparative analysis of size square wave converter topologies (SMPS), selected for high output power and low output voltage, is performed for the secondary-side components. This analysis is realized for chokes, the capacitive component and scondary- side power rectifiers under consideration of parasitics. Objective is with regard to progressive miniaturization of SMPS's, to increase the power density and to reduce power-losses by choice of a suitable circuit concept. The obtained results are normalized in terms of converter specifications and operational parameters. Hence general conclusions are gained. A comparative design example is worked out for a 5 V /100 A converter.

   HIGH POWER TRANSISTOR INVERTER WITH NOVEL PROTECTION SCHEME
By A. Ackva; Th. Reckhorn [View]
[Download]

Abstract: In this paper a voltage source inverter for currents up to 400 A is presented. Its main features are an optimum base drive with low power losses and short-circuit capability. Simple construction is achieved by using power transistor modules and no snubbers. Furthermore uncontrolled switching of the device in the event of the breakdown and consequent return of the base drive power supply at full dc-link voltage is avoided by a novel protection circuit.

   CONTROL STRATEGY AND TOPOLOGICAL STUDY OF A NOVEL SINGLE PHASE REGENERATIVE AC/DC CONVERTER FEEDING A DC SERVO MOTOR
By C. Cyr; K. AI-Haddad; G. Joos; P. D. Ziogas [View]
[Download]

Abstract: A single phase converter allowing regeneration of the energy recovered by a four-quadrant chopper is presented and analysed in this paper. The topology of the converter is based on a regenerative two-quadrant bridge, using diodes in parallel with reverse connected transistors allowing bi-directional current flow. This stage is directly connected to a standard four quadrant chopper without dc link filtering. It result in a very compact converter for high performance DC servo-drives. The control scheme ensures low energy losses in the power semiconductors, a unity displacement factor and a perfect control of the power flow between the DC motor and the AC source. Experimental results confirm that the converter is fully regenerative and that the transfer from motoring to regeneration is instantaneous. An AC line filter is used to eliminate the high order harmonics component caused by the chopper and make this novel topology look like a standard diode bridge from the AC supply point of view.

   THE DEFINITION AND IMPORTANCE OF POWER FACTOR FOR POWER ELECTRONIC CONVERTERS
By W. F. Ray; R. M. Davis [View]
[Download]

Abstract: With the significant increase in use of power electronic circuits and the consequent increase in harmonic content the value of power factor as a simple measure of goodness of power utilisation is questionable. Reactive power in the presence of harmonics has little meaning and the cosinusoidal definition of power factor inadequate. The paper summarises the supply authority regulations and reviews the various methods used for measuring power factor. It then examines the definition and relevance of power factor with non-linear and unbalanced loads and unbalanced supplies. A 3-phase rectifier feeding a capacitive dc link is a particular example where harmonics are largely governed by supply impedance and where small supply unbalance gives significant unbalance in line currents. It is therefore difficult for manufacturers to specify values for power factor and harmonic content appropriate to a particular user. The paper concludes that a code of practice placing minimum limits on front end line reactance for power electronic equipment would be easier to implement than maximum limits on harmonic content.

   POWER ELECTRONIC CIRCUIT SIMULATION USING BOND GRAPH TECHNIQUES
By G. M. Asher; V. Eslamdoost [View]
[Download]

Abstract: The paper introduces the Bond Graph technique for the modelling of electronic switching circuits. Rules for the derivation of both the Bond Graph and the defining system equations for a general problem are given. The highly useful concept of the Junction Structure Matrix is introduced and a new switch model is presented which, with the aid of Bond Graph concept results in a very simple method for changing the system equations upon switching. lt is shown that the Junction Structure Matrix can incorporate other Switching strategies and may form the basis of a general package offering various methodologies for the modelling of Switching devices.

   AN AC TO DC CONVERTER WITH OUTPUT CURRENT REVERSATION
By D. Milly [View]
[Download]

Abstract: The author of the present paper describes the a.c. to d.c.converter suitable for feeding of voltage inverters and d.c. motors, which represents a series connection of a controlled rectifier with output voltage reversation and a two quadrant d.c. to d.c. converter. The converter makes bidirectional energy flow possible by the load current reversation, while both lower and higher positive voltage can be achieved on the converter output, comparing with the maximum a.c. voltage value. If a PWM controlled rectifier on the input of the converter is used, it is possible to achieve sinusoidal input a.c. currents, almost unit power factor and current source reactor minimization. Since almost no danger of current and voltage surges exists in the a.c. to d.c. converter the swithing devices are little stressed and the converter operates reliably.

   THREE-PHASE AC/AC CONVERTER FEEDING AN UNBALANCED LOAD: UNBALANCE AND HARMONICS: PRACTICAL APPLICATIONS
By P. Goerger; C. Rombaut [View]
[Download]

Abstract: Several types of AC/AC converters may be used in order to regulate the power provided to an unbalanced resistant 3-phase receiver. The different structures are compared, in terms of the harmonics injected into the supply as well as of the unbalance of the absorbed currents. By use of a symmetrical control, the all-thyristor AC/AC converter is the model which offers the lowest overall harmonic level, as well as being the only one where the unbalance is reduced when the regulating is increased. Such properties may be used for purposes of supply from a 3-phases network with a mid-point resistances. The only value in using dissymmetrical control is for three single-phase AC/AC converters in delta configuration. It allows for the cancellation of the inverted component of the absorbed current fundamental. The use of a highly simplified dissymmetrical control enables the unbalance to be considerably reduced.

EPE 1989 - 35 - Dialogue Session 2.2: CONVERTERS AND INVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1989 - Conference > EPE 1989 - 35 - Dialogue Session 2.2: CONVERTERS AND INVERTERS
	[return to parent folder]

	AN ENERGY CONVERSION SYSTEM FOR AN IMPLANTABLE ARTIFICIAL HEART USING SIRETS By Toshi Hiro Nishimura; Masao Saito; Leo Lorenz	[View] [Download]
Abstract: Developing in power electronics and other advanced electronic technology, a novel trends in the techniques for internal organs such as an implantable artificial heart system is arising. It comes not only from the medical electronics but also from the techniques of a high frequency power conversion using resonant converters. This paper describes the energy conversion method for implanted artificial heart using a nobel resonant converter with SIRET and artificial heart driven system.

	LINE SIDE BEHAVIOUR OF UNCONTROLLED RECTIFIER BRIDGES WITH CAPACITIVE DC SMOOTHING By M. Grötzbach; B. Draxler	[View] [Download]
Abstract: Small power rectifier bridges with capacitive dc smoothing work generally with a discontinuous dc current. This leads to significant deviations in the spectrum of the line harmonics compared with the known values of a good dc current smoothing. Starting from the differential and switching equations at the dc side, an analytical based direct solution of the steady state problem is proposed via difference equations. The calculation of the unknown switching points is carried out numerically due to the analytical effort. The line current can easily be obtained from the time behaviour of the dc current and with the help of a FFT-standard routine the associated spectrum is evaluated. Circuit data line impedance and dc capacitor as well as the operating point given by the dc output current are used as parameters. The results show the influence of these parameters on the line harmonics in amplitude and phase as well as the behaviour of the fundamental harmonic content and the displacement factor.

	SMALL VOLTAGE FLUCTUATIONS BY THE MANAGEMENT OF SHORT MULTICYCLE CONTROL By R. Kersten	[View] [Download]
Abstract: The electric power control of thermal houshold appliances must be brought into accord with IEC 555 (low voltage fluctuations, harmonics and direct currents) which is difficult for halogen heaters because of their high starting currents. A computational analysis was made including the thermal time behaviour of incandescent lamps, their dynamical electric loads and their influence on the flickermeter output. A solution is presented using three triacs for the synchronous multicycle control of two halogen lamps. Besides the well known basic power steps in series, diodes antiparallel, and parallel the time management of half wave control enables additional power steps between with low voltage fluctuations and fundamental frequencies of 16 2/3 Hz. As a result quasicontinuous control is possible between 5% and full power (2-3 kW).

	COMPARATIVE ANALYSIS OF HIGH CURRENT COMPONENTS IN PWM CONTROLLED CONVERTER TOPOLOGIES QUALIFIED FOR HIGH OUTPUT POWER AND LOW OUTPUT VOLTAGE By L. Heinemann; N. Fröhleke	[View] [Download]
Abstract: A comparative analysis of size square wave converter topologies (SMPS), selected for high output power and low output voltage, is performed for the secondary-side components. This analysis is realized for chokes, the capacitive component and scondary- side power rectifiers under consideration of parasitics. Objective is with regard to progressive miniaturization of SMPS's, to increase the power density and to reduce power-losses by choice of a suitable circuit concept. The obtained results are normalized in terms of converter specifications and operational parameters. Hence general conclusions are gained. A comparative design example is worked out for a 5 V /100 A converter.

	HIGH POWER TRANSISTOR INVERTER WITH NOVEL PROTECTION SCHEME By A. Ackva; Th. Reckhorn	[View] [Download]
Abstract: In this paper a voltage source inverter for currents up to 400 A is presented. Its main features are an optimum base drive with low power losses and short-circuit capability. Simple construction is achieved by using power transistor modules and no snubbers. Furthermore uncontrolled switching of the device in the event of the breakdown and consequent return of the base drive power supply at full dc-link voltage is avoided by a novel protection circuit.

	CONTROL STRATEGY AND TOPOLOGICAL STUDY OF A NOVEL SINGLE PHASE REGENERATIVE AC/DC CONVERTER FEEDING A DC SERVO MOTOR By C. Cyr; K. AI-Haddad; G. Joos; P. D. Ziogas	[View] [Download]
Abstract: A single phase converter allowing regeneration of the energy recovered by a four-quadrant chopper is presented and analysed in this paper. The topology of the converter is based on a regenerative two-quadrant bridge, using diodes in parallel with reverse connected transistors allowing bi-directional current flow. This stage is directly connected to a standard four quadrant chopper without dc link filtering. It result in a very compact converter for high performance DC servo-drives. The control scheme ensures low energy losses in the power semiconductors, a unity displacement factor and a perfect control of the power flow between the DC motor and the AC source. Experimental results confirm that the converter is fully regenerative and that the transfer from motoring to regeneration is instantaneous. An AC line filter is used to eliminate the high order harmonics component caused by the chopper and make this novel topology look like a standard diode bridge from the AC supply point of view.

	THE DEFINITION AND IMPORTANCE OF POWER FACTOR FOR POWER ELECTRONIC CONVERTERS By W. F. Ray; R. M. Davis	[View] [Download]
Abstract: With the significant increase in use of power electronic circuits and the consequent increase in harmonic content the value of power factor as a simple measure of goodness of power utilisation is questionable. Reactive power in the presence of harmonics has little meaning and the cosinusoidal definition of power factor inadequate. The paper summarises the supply authority regulations and reviews the various methods used for measuring power factor. It then examines the definition and relevance of power factor with non-linear and unbalanced loads and unbalanced supplies. A 3-phase rectifier feeding a capacitive dc link is a particular example where harmonics are largely governed by supply impedance and where small supply unbalance gives significant unbalance in line currents. It is therefore difficult for manufacturers to specify values for power factor and harmonic content appropriate to a particular user. The paper concludes that a code of practice placing minimum limits on front end line reactance for power electronic equipment would be easier to implement than maximum limits on harmonic content.

	POWER ELECTRONIC CIRCUIT SIMULATION USING BOND GRAPH TECHNIQUES By G. M. Asher; V. Eslamdoost	[View] [Download]
Abstract: The paper introduces the Bond Graph technique for the modelling of electronic switching circuits. Rules for the derivation of both the Bond Graph and the defining system equations for a general problem are given. The highly useful concept of the Junction Structure Matrix is introduced and a new switch model is presented which, with the aid of Bond Graph concept results in a very simple method for changing the system equations upon switching. lt is shown that the Junction Structure Matrix can incorporate other Switching strategies and may form the basis of a general package offering various methodologies for the modelling of Switching devices.

	AN AC TO DC CONVERTER WITH OUTPUT CURRENT REVERSATION By D. Milly	[View] [Download]
Abstract: The author of the present paper describes the a.c. to d.c.converter suitable for feeding of voltage inverters and d.c. motors, which represents a series connection of a controlled rectifier with output voltage reversation and a two quadrant d.c. to d.c. converter. The converter makes bidirectional energy flow possible by the load current reversation, while both lower and higher positive voltage can be achieved on the converter output, comparing with the maximum a.c. voltage value. If a PWM controlled rectifier on the input of the converter is used, it is possible to achieve sinusoidal input a.c. currents, almost unit power factor and current source reactor minimization. Since almost no danger of current and voltage surges exists in the a.c. to d.c. converter the swithing devices are little stressed and the converter operates reliably.

	THREE-PHASE AC/AC CONVERTER FEEDING AN UNBALANCED LOAD: UNBALANCE AND HARMONICS: PRACTICAL APPLICATIONS By P. Goerger; C. Rombaut	[View] [Download]
Abstract: Several types of AC/AC converters may be used in order to regulate the power provided to an unbalanced resistant 3-phase receiver. The different structures are compared, in terms of the harmonics injected into the supply as well as of the unbalance of the absorbed currents. By use of a symmetrical control, the all-thyristor AC/AC converter is the model which offers the lowest overall harmonic level, as well as being the only one where the unbalance is reduced when the regulating is increased. Such properties may be used for purposes of supply from a 3-phases network with a mid-point resistances. The only value in using dissymmetrical control is for three single-phase AC/AC converters in delta configuration. It allows for the cancellation of the inverted component of the absorbed current fundamental. The use of a highly simplified dissymmetrical control enables the unbalance to be considerably reduced.