EPE Association: EPE 1997 – 79: Dialogue Session DS2b: POWER CONVERTERS

EPE 1997 – 79: Dialogue Session DS2b: POWER CONVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1997 - Conference > EPE 1997 – 79: Dialogue Session DS2b: POWER CONVERTERS

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   THYRISTOR POWER SUPPLIES FOR PLASMA TECHNOLOGY
By T. Tomson; A. Marotta; H. Hoppe de Souza [View]
[Download]

Abstract: Group performance of plasma torches with electronic power supply based on controlled (thyristor) rectifiers with common devices and group performance of (semi)controlled rectifiers with a common controller and a common single plasma torch are analyzed in the present article.

   AN IMPROVED THREE-PHASE DIODE RECTIFIER FOR REDUCING AC LINE CURRENT HARMONICS
By Shigeo Masukawa; Shoji Iida [View]
[Download]

Abstract: In this paper, a novel method to reduce harmonics involved in ac line currents of a three-phase diode rectifier circuit with a smoothing reactor is proposed. This circuit consists of passive components and diodes only. It is applied to the conventional three-phase diode rectifier, and an auxiliary circuit composed of transformers, capacitors and diodes is added. Ac line current waveforms of proposed· circuit equal to 12-step currents which correspond to the conventional 12-phase diode rectifier. In this paper, circuit performance of the proposed method are discussed by analyzing waveforms in the circuit, and optimum parameter is derived. Then, effects on harmonics reductions can be clarified by theoretical and experimental results, and ratings of system components are investigated.

   OPTIMIZING SWITCHING LOSSES AND EMC OF PULSE CONTROLLED INVERTERS USING EMC-SNUBBER CIRCUITS
By B. Orlik: O. Scheuer [View]
[Download]

Abstract: In general pulse-controlled inverters are used as output modules in d.c. link frequency converters. They are working with hard-switching valves, for example IGBTs. The practical operation of EMC-snubber circuits of power modules combined with intelligent vector-modulators can both guarantee observance ofEMC-guidelines and minimize switching power losses. In the following the results of this operation will be presented.

   DC LINK CURRENTS IN BI-DIRECTIONAL POWER CONVERTERS WITH COORDINATED PULSE PATTERNS
By L. Sack [View]
[Download]

Abstract: For the selection of the DC link capacitor in voltage source inverters, the AC current through the capacitor is very important, as it increases the internal temperature by power dissipation and so influences the life time of the capacitor. In bidirectional power converters, the line side and the motor side inverter make a contribution on the current in the DC link capacitor. In the paper these currents are analysed at first. The influence of the operating point is shown with respect to the speed range of an inverter drive. Relating to the stress of the DC link capacitor by AC current two different cases can be distinguished: for unequal switching frequencies of the line side and the motor side inverter the harmonics in the currents in the DC link are independent from each other and form their. own RMS values. In the other case the switching frequencies are equal; the superposition of the harmonics yields the RMS value, which depends among other things on the displacement angle between the pulse patterns of both inverters. This additional degree of freedom can be used to minimize ·the AC current of the DC link capacitor.

   THE SPACE VECTOR CONTROL OF THE PWM-RECTIFIER USING U/F REFERENCES
By J. Ollila [View]
[Download]

Abstract: With a three phase mains interface the PWM -rectifier is a high performance solution to reduce line current distortion and to provide regenerative braking capability in motor drive applications. This paper introduces a space vector based control strategy, which is used to modify a standard U/F-controlled inverter to work as a PWM-rectifier. Compared to the conventional phase angle/magnitude control strategy, this new space vector based control strategy gives much faster response and permits smaller intermediate capacitor due to tight power balance. Using the proposed strategy, the complete drive can be constructed using two standard motor inverters, and a small LCL-type line filter. After installation, the line bridge is configured by simply downloading the software.

   COMPARISON OF STATE OF THE ART GATE DRIVE TECHNIQUES FOR HIGH SIDE SWITCH
By I. Zverev; S. Konrad; V. Schilling; J. Petzoldt [View]
[Download]

Abstract: Various gate drive techniques were compared in hard switching power converters with DC-Voltage link and OC-Current link. The comparison criteria were defined as realization of the gate drive circuitry, expenses and conducted EMIbehavior. Gate drive without potential separation represents a good solution concerning conducted EMI performance and expense. Bootstrap and level shifter are elements of gate drive without potential separation. Level shifter operating principle, mechanism of interference influence and technical solutions for increase of the noise immunity are discussed in detail.

   Analysis of Phase-Shift Controlled AC-AC Converters Based on Switching Vector Theory
By Jorma Kyyrä [View]
[Download]

Abstract: The only general possibility to analytically analyse phase-shift controlled ac-ac converters is switching technique. It uses switching functions and their Fourier-series to analyse input current and output voltage of the converter. However, this kind of calculations are very cumbersome and difficult to follow. In this paper a new method, based on space-vector of switching functions is discussed. It is a powerful tool and in some cases even analytical equations for the output voltage harmonics are obtained.

   THE ENERGY EFFICIENT DEFENCE CIRCUITS OF THE COMMUTER TRAIN CONVERTERS
By S.I. Volsky; P. V. Butenko; E. A. Lomonova; J. B. Klaassens; A. B. Uan-Zo-li [View]
[Download]

Abstract: This paper presents a new attractive approach to design the energy efficient defence circuits of high-frequency thyristors converters with unstable high DC-voltage input supply [1,2]. Specifically, such thyristor converters can be used in commuter train DC/DC conversion of an input unstable high DC-voltage (2-4 kV) to the required load stable DC-voltages (50 V, 1500 V) through the high frequency AC link. The developed synthesis algorithm of the defence circuits parameters is based on the simulation and complex analysis of the transient phenomena and total energy losses over one period. The employment of this algorithm allowed to decrease the energy losses in the defence circuits for the power converters of the commuter train on more than 30%.

   A NEW FORWARD CONVERTER USING A NONDISSIPATIVE SNUBBER
By J. A. Correa Pinto; A. A. Pereira; V. J. Farias; L. C. de Freitas; J. B. Vieira Jr. [View]
[Download]

Abstract: This paper presents a steady-state analysis with complete characterization of the converter operation. The non-dissipative snubber associated with a Forward converter provides the soft switching. The proposed approach allows building a converter with high frequency of operation. A detailed analysis of the operation is presented. The output voltage is controlled by PWM with constant frequency. The complete operating principles, theoretical analysis, relevant equations, simulation and experimental results are presented.

   WATERCOOLED GTO COMPACT CONVERTER
By H. Baumann; J. Scholten; M. Zengerle [View]
[Download]

Abstract: A new GTO converter has been designed for heavy mass transit vehicles. Due to environmental saving watercooling has been applied. The compact design of the converter and its water cooling system is presented. The simulation algorithm for the temperature of the critical components is briefly presented.

   AN OPTIMISED ENERGY RECOVERY SNUBBER CIRCUIT FOR SWITCHING POWER CONVERTERS
By Diana Izvorska; Joe Leisten; Roumen Petkov [View]
[Download]

Abstract: A nondissipative snubber has been used to reduce the switching power loss in a PWM buck converter. The snubber consists of one inductive element, two capacitive elements and three diodes. It has been established that a fixed relationship between the snubber component values provides the best snubber performance. Optimized design of the nondissipative snubber is therefore reduced to the problem of selecting a snubber capacitor value in order to minimize the total circuit power loss. A large snubber capacitor will provide the lowest switch dynamic power loss. Unfortunately, a large capacitor also leads to increased residual power loss in the snubber components, particularly in the snubber diodes. An optimum snubber capacitor value, therefore, exists which minimizes the combined residual snubber loss and the switch dynamic loss. An analysis of the nondissipative snubber circuit is described leading to a design process which determines the optimum snubber component values. These values are found to depend upon the transition characteristics of the power switch. Optimum snubber designs have been produced for ultra-fast, fast and standard IGBT power switches. The total power loss of these IGBT devices including the optimized snubber has been compared in a particular 2.2kW power converter topology.

   PROTECTIVE DEVICE FOR ELECTRONIC TAP CHANGER FOR DISTRIBUTION TRANSFORMERS
By P. Bauer; S.W.H. de Haan [View]
[Download]

Abstract: Electronic crowbar consisting of power semiconductor switches is studied. The crowbar special function in the distribution transformer !OkV/380 V allows to replace mechanical tap changer with one consisting of power electronics components. The crowbar can carry transformer short circuit current and during the switching on of a transformer acts as closed switch. Theoretical smdy is complemented with simulations and experimental measurements.

   A NOVEL DIRECT FREQUENCY CONVERTER STRUCTURE CONTROLLED BY A COOPERATIVE-PREDICTIVE ALGORITHM
By E. P. Wiechmann; R. P. Burgos; J. R. Rodriguez [View]
[Download]

Abstract: This paper presents a novel direct frequency converter structure controlled by a cooperative-predictive algorithm. The converter operates with a maximum load current distortion of 4 %, and keeps its commutation frequency below 550Hz. These facts, combined with the overall ac-ac voltage gain of3.5l, makes the proposed converter Suitable for medium voltage adjustable speed drives. 1bis is further motivated by the use of the multiple secondary windings transformer, and the converter's own structure, which eliminate the need for the step-up transformer required by conventional medium voltage drives to supply the motor load. Consequently, the transformer windings V A rating is reduced by 50 %. The transformer employed also produces a multi-pulse operation towards the utility side, improving the converter's input current distortion and input power factor.

   HIGH POWER SOFT SWITCHING PWM IGBT CONVERTER ELECTRICAL AND EMC CHARACTERIZATION
By S. Cazabat; W. Melhem; A. Puzo; J. Gonzalez; F. Forest; R. Critchley; H. Pouliquen [View]
[Download]

Abstract: The soft switching technique has proven to be a very interesting solution for low and medium power systems aiming to reduce hard switching constraints. In high power, very few applications exist. This following paper presents the analysis and the results obtained with a two phases high power soft switching (ZVS) IGBT converter. The control sequences are described as well as the comparison between hard and soft switching about losses and ElectroMagnetic Interferences.

   HIGH POWER FACTOR, HIGH EFFICIENCY BIDIRECTIONAL GTO RECTIFIERS FOR LOCOMOTIVE APPLICATION
By J. Bou Saada; P. Colignon; P. Thomas; F. Avaux; L. Delporte; F. Mathys [View]
[Download]

Abstract: This paper describes a control strategy for a bidirectional rectifier supplying the DC link of an asynchronous traction drive for locomotive. Main constraints were a power factor near one, the respect ofhannonic criteria related to signalling and a high efficiency. All aspects are presented: design method, simulations, control, measures on prototype.

   MODULAR HIGH POWER DC-LINK CONVERTER UNITS FOR POWER SYSTEM APPLICATION
By P. G. Kamp; B. Endres; M. Wolf [View]
[Download]

Abstract: High Power voltage source converter units for the power system application have been developed. The wide power range from 5 to 40 MVA is realised by water-cooled converter modules in two-level or three-level technique. Their electrical arrangement and applications are described. Special attention is focused on internal faults.

EPE 1997 – 79: Dialogue Session DS2b: POWER CONVERTERS
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1997 - Conference > EPE 1997 – 79: Dialogue Session DS2b: POWER CONVERTERS
	[return to parent folder]

	THYRISTOR POWER SUPPLIES FOR PLASMA TECHNOLOGY By T. Tomson; A. Marotta; H. Hoppe de Souza	[View] [Download]
Abstract: Group performance of plasma torches with electronic power supply based on controlled (thyristor) rectifiers with common devices and group performance of (semi)controlled rectifiers with a common controller and a common single plasma torch are analyzed in the present article.

	AN IMPROVED THREE-PHASE DIODE RECTIFIER FOR REDUCING AC LINE CURRENT HARMONICS By Shigeo Masukawa; Shoji Iida	[View] [Download]
Abstract: In this paper, a novel method to reduce harmonics involved in ac line currents of a three-phase diode rectifier circuit with a smoothing reactor is proposed. This circuit consists of passive components and diodes only. It is applied to the conventional three-phase diode rectifier, and an auxiliary circuit composed of transformers, capacitors and diodes is added. Ac line current waveforms of proposed· circuit equal to 12-step currents which correspond to the conventional 12-phase diode rectifier. In this paper, circuit performance of the proposed method are discussed by analyzing waveforms in the circuit, and optimum parameter is derived. Then, effects on harmonics reductions can be clarified by theoretical and experimental results, and ratings of system components are investigated.

	OPTIMIZING SWITCHING LOSSES AND EMC OF PULSE CONTROLLED INVERTERS USING EMC-SNUBBER CIRCUITS By B. Orlik: O. Scheuer	[View] [Download]
Abstract: In general pulse-controlled inverters are used as output modules in d.c. link frequency converters. They are working with hard-switching valves, for example IGBTs. The practical operation of EMC-snubber circuits of power modules combined with intelligent vector-modulators can both guarantee observance ofEMC-guidelines and minimize switching power losses. In the following the results of this operation will be presented.

	DC LINK CURRENTS IN BI-DIRECTIONAL POWER CONVERTERS WITH COORDINATED PULSE PATTERNS By L. Sack	[View] [Download]
Abstract: For the selection of the DC link capacitor in voltage source inverters, the AC current through the capacitor is very important, as it increases the internal temperature by power dissipation and so influences the life time of the capacitor. In bidirectional power converters, the line side and the motor side inverter make a contribution on the current in the DC link capacitor. In the paper these currents are analysed at first. The influence of the operating point is shown with respect to the speed range of an inverter drive. Relating to the stress of the DC link capacitor by AC current two different cases can be distinguished: for unequal switching frequencies of the line side and the motor side inverter the harmonics in the currents in the DC link are independent from each other and form their. own RMS values. In the other case the switching frequencies are equal; the superposition of the harmonics yields the RMS value, which depends among other things on the displacement angle between the pulse patterns of both inverters. This additional degree of freedom can be used to minimize ·the AC current of the DC link capacitor.

	THE SPACE VECTOR CONTROL OF THE PWM-RECTIFIER USING U/F REFERENCES By J. Ollila	[View] [Download]
Abstract: With a three phase mains interface the PWM -rectifier is a high performance solution to reduce line current distortion and to provide regenerative braking capability in motor drive applications. This paper introduces a space vector based control strategy, which is used to modify a standard U/F-controlled inverter to work as a PWM-rectifier. Compared to the conventional phase angle/magnitude control strategy, this new space vector based control strategy gives much faster response and permits smaller intermediate capacitor due to tight power balance. Using the proposed strategy, the complete drive can be constructed using two standard motor inverters, and a small LCL-type line filter. After installation, the line bridge is configured by simply downloading the software.

	COMPARISON OF STATE OF THE ART GATE DRIVE TECHNIQUES FOR HIGH SIDE SWITCH By I. Zverev; S. Konrad; V. Schilling; J. Petzoldt	[View] [Download]
Abstract: Various gate drive techniques were compared in hard switching power converters with DC-Voltage link and OC-Current link. The comparison criteria were defined as realization of the gate drive circuitry, expenses and conducted EMIbehavior. Gate drive without potential separation represents a good solution concerning conducted EMI performance and expense. Bootstrap and level shifter are elements of gate drive without potential separation. Level shifter operating principle, mechanism of interference influence and technical solutions for increase of the noise immunity are discussed in detail.

	Analysis of Phase-Shift Controlled AC-AC Converters Based on Switching Vector Theory By Jorma Kyyrä	[View] [Download]
Abstract: The only general possibility to analytically analyse phase-shift controlled ac-ac converters is switching technique. It uses switching functions and their Fourier-series to analyse input current and output voltage of the converter. However, this kind of calculations are very cumbersome and difficult to follow. In this paper a new method, based on space-vector of switching functions is discussed. It is a powerful tool and in some cases even analytical equations for the output voltage harmonics are obtained.

	THE ENERGY EFFICIENT DEFENCE CIRCUITS OF THE COMMUTER TRAIN CONVERTERS By S.I. Volsky; P. V. Butenko; E. A. Lomonova; J. B. Klaassens; A. B. Uan-Zo-li	[View] [Download]
Abstract: This paper presents a new attractive approach to design the energy efficient defence circuits of high-frequency thyristors converters with unstable high DC-voltage input supply [1,2]. Specifically, such thyristor converters can be used in commuter train DC/DC conversion of an input unstable high DC-voltage (2-4 kV) to the required load stable DC-voltages (50 V, 1500 V) through the high frequency AC link. The developed synthesis algorithm of the defence circuits parameters is based on the simulation and complex analysis of the transient phenomena and total energy losses over one period. The employment of this algorithm allowed to decrease the energy losses in the defence circuits for the power converters of the commuter train on more than 30%.

	A NEW FORWARD CONVERTER USING A NONDISSIPATIVE SNUBBER By J. A. Correa Pinto; A. A. Pereira; V. J. Farias; L. C. de Freitas; J. B. Vieira Jr.	[View] [Download]
Abstract: This paper presents a steady-state analysis with complete characterization of the converter operation. The non-dissipative snubber associated with a Forward converter provides the soft switching. The proposed approach allows building a converter with high frequency of operation. A detailed analysis of the operation is presented. The output voltage is controlled by PWM with constant frequency. The complete operating principles, theoretical analysis, relevant equations, simulation and experimental results are presented.

	WATERCOOLED GTO COMPACT CONVERTER By H. Baumann; J. Scholten; M. Zengerle	[View] [Download]
Abstract: A new GTO converter has been designed for heavy mass transit vehicles. Due to environmental saving watercooling has been applied. The compact design of the converter and its water cooling system is presented. The simulation algorithm for the temperature of the critical components is briefly presented.

	AN OPTIMISED ENERGY RECOVERY SNUBBER CIRCUIT FOR SWITCHING POWER CONVERTERS By Diana Izvorska; Joe Leisten; Roumen Petkov	[View] [Download]
Abstract: A nondissipative snubber has been used to reduce the switching power loss in a PWM buck converter. The snubber consists of one inductive element, two capacitive elements and three diodes. It has been established that a fixed relationship between the snubber component values provides the best snubber performance. Optimized design of the nondissipative snubber is therefore reduced to the problem of selecting a snubber capacitor value in order to minimize the total circuit power loss. A large snubber capacitor will provide the lowest switch dynamic power loss. Unfortunately, a large capacitor also leads to increased residual power loss in the snubber components, particularly in the snubber diodes. An optimum snubber capacitor value, therefore, exists which minimizes the combined residual snubber loss and the switch dynamic loss. An analysis of the nondissipative snubber circuit is described leading to a design process which determines the optimum snubber component values. These values are found to depend upon the transition characteristics of the power switch. Optimum snubber designs have been produced for ultra-fast, fast and standard IGBT power switches. The total power loss of these IGBT devices including the optimized snubber has been compared in a particular 2.2kW power converter topology.

	PROTECTIVE DEVICE FOR ELECTRONIC TAP CHANGER FOR DISTRIBUTION TRANSFORMERS By P. Bauer; S.W.H. de Haan	[View] [Download]
Abstract: Electronic crowbar consisting of power semiconductor switches is studied. The crowbar special function in the distribution transformer !OkV/380 V allows to replace mechanical tap changer with one consisting of power electronics components. The crowbar can carry transformer short circuit current and during the switching on of a transformer acts as closed switch. Theoretical smdy is complemented with simulations and experimental measurements.

	A NOVEL DIRECT FREQUENCY CONVERTER STRUCTURE CONTROLLED BY A COOPERATIVE-PREDICTIVE ALGORITHM By E. P. Wiechmann; R. P. Burgos; J. R. Rodriguez	[View] [Download]
Abstract: This paper presents a novel direct frequency converter structure controlled by a cooperative-predictive algorithm. The converter operates with a maximum load current distortion of 4 %, and keeps its commutation frequency below 550Hz. These facts, combined with the overall ac-ac voltage gain of3.5l, makes the proposed converter Suitable for medium voltage adjustable speed drives. 1bis is further motivated by the use of the multiple secondary windings transformer, and the converter's own structure, which eliminate the need for the step-up transformer required by conventional medium voltage drives to supply the motor load. Consequently, the transformer windings V A rating is reduced by 50 %. The transformer employed also produces a multi-pulse operation towards the utility side, improving the converter's input current distortion and input power factor.

	HIGH POWER SOFT SWITCHING PWM IGBT CONVERTER ELECTRICAL AND EMC CHARACTERIZATION By S. Cazabat; W. Melhem; A. Puzo; J. Gonzalez; F. Forest; R. Critchley; H. Pouliquen	[View] [Download]
Abstract: The soft switching technique has proven to be a very interesting solution for low and medium power systems aiming to reduce hard switching constraints. In high power, very few applications exist. This following paper presents the analysis and the results obtained with a two phases high power soft switching (ZVS) IGBT converter. The control sequences are described as well as the comparison between hard and soft switching about losses and ElectroMagnetic Interferences.

	HIGH POWER FACTOR, HIGH EFFICIENCY BIDIRECTIONAL GTO RECTIFIERS FOR LOCOMOTIVE APPLICATION By J. Bou Saada; P. Colignon; P. Thomas; F. Avaux; L. Delporte; F. Mathys	[View] [Download]
Abstract: This paper describes a control strategy for a bidirectional rectifier supplying the DC link of an asynchronous traction drive for locomotive. Main constraints were a power factor near one, the respect ofhannonic criteria related to signalling and a high efficiency. All aspects are presented: design method, simulations, control, measures on prototype.

	MODULAR HIGH POWER DC-LINK CONVERTER UNITS FOR POWER SYSTEM APPLICATION By P. G. Kamp; B. Endres; M. Wolf	[View] [Download]
Abstract: High Power voltage source converter units for the power system application have been developed. The wide power range from 5 to 40 MVA is realised by water-cooled converter modules in two-level or three-level technique. Their electrical arrangement and applications are described. Special attention is focused on internal faults.