EPE Association: NORpie 2004 - Topic 02: Converters

NORpie 2004 - Topic 02: Converters
You are here: EPE Documents > 05 - EPE Supported Conference Proceedings > NORpie - Proceedings > NORpie 2004 > NORpie 2004 - Topic 02: Converters

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   Pulse Rectifiers Current-Type for Applications in Modern Frequency Converters
By P. Hlisnikovsky; P. Chlebis [View]
[Download]

Abstract: This document occupy with the pulse rectifier current-type as a modern controlled rectifier, which is very suitable as an input unit of indirect frequency converters current-type, because its low emissions of harmonics into the network, the controlled power factor and the controlled current in DC link. There is a comparison between the pulse rectifier and the classical thyristor rectifier. There is a description of the zero current switch pulse rectifier as suitable input unit of indirect frequency converter current-type with the series resonant DC-link. The vector pulse width modulation and the delta modulation as the suitable control methods for the pulse rectifiers or for the whole frequency converter are also described in the contribution. The measured results on the realized physical models are enclosed at the end of the contribution.

   Paralleled three-phase inverters
By E. Hoff; T. Skjellnes; L. Norum [View]
[Download]

Abstract: Paralleling of inverters are useful for a number of reasons, where modularity and redundancy are some of the key points. Load sharing and voltage control may be done using different methods. The three-phase voltage is controlled by either using fixed frame, áâ-coordinates, or synchronized frame, dqcoordinates. Models for the dynamic behavior of paralleled inverters will be investigated through Matlab Simulink simulations.

   Dimensioning of a Current Source Inverter for the Feed-in of Electrical Energy from Fuel Cells to the Mains
By M. Mohr; M. Bierhoff; F.W. Fuchs [View]
[Download]

Abstract: Fuel cells deliver dc current which demands a dc/ac converter between the fuel cell and the mains to feed in electrical energy. An inverter of the current source type makes it possible to convert the energy supplied by a fuel cell into the mains without using an auxiliary dc/dc-converter. The current source inverter’s efficiency depends on the input dc voltage of the inverter, so the rating of the fuel cell voltage influences the overall efficiency of the system. After a short introduction of the fuel cell’s electrical behaviour, the current source inverter and the impact of its LCFilter on the inverter’s input voltage are described. The dimensioning process dependent on the power range of the fuel cell and the current source inverter is shown. In doing so, the characteristics of the fuel cell and the inverter are taken into account. A laboratory setup of a current source inverter has been built and a control scheme is presented. Simulation results of the general system behaviour are shown.

   Comparison of commutation transients of inverters with silicon carbide JFETs with and without body diodes
By B. Allebrand; H.-P. Nee [View]
[Download]

Abstract: An inverter could be built by using silcon carbide power switches only. This can be done by using SiC JFETs which can conduct current in both directions. An interesting question is how an inverter using SiC JFETs with a body diode compares with an inverter using SiC JFETs without body diodes. This will be discussed in this paper.

   Power device selection and a comparative study of transistor technologies for a Zero Voltage Switching Buck Converter
By P. Andreassen; T. Undeland [View]
[Download]

Abstract: The new ultra thin wafer technology makes it possible to make Non Punch Through (NPT) IGBTs in the 600V range, with a lightly doped collector. This new IGBT technology is tested and compared with other competitive transistor technologies. The case study of the Zero Voltage Switching (ZVS) Buck Converter is performed because this topology until now has favored the use of MOSFETs.

   A Systematic Approach to Analyze the Stability of Distributed Power Supply Systems
By A. Hentunen; K. Zenger; T. Suntio [View]
[Download]

Abstract: A systematic approach is presented to analyze the stability of distributed power supply systems. In this paper, unterminated modeling technique is applied to obtain a transfer function model between the inputs and outputs of a distributed power supply system. This transfer function model allows us to study bounded-input-bounded-output stability.

   Synchronous Communication Link for IGBT Gate Driver Units
By T. Kjellqvist [View]
[Download]

Abstract: New inverter topologies and series connection of IGBTs require more intelligent gate drivers and faster communication links. Also, higher voltages require better electrical insulation and the communication distance increase. Most gate diver units utilize some kind of asynchronous communication protocol where the length of the pulse is varied to distinguish between different symbols on the link. The communication protocol is easily implemented in discrete logic. Using a synchronous protocol allow for an increased number of messages and a shorter latency since timing is improved compared to any asynchronous protocol. Alternatively, system frequency can be reduced and thereby reducing power consumption. In some applications programmable logic is already present due to the need of sophisticated control of the device and more complex communication protocol can be implemented with a limited amount of extra hardware. The link can easily be used for low speed communication in parallel to the modulation signaling. This low speed channel can be used for configuration of the gate driver or communicating chip temperature to the modulator.

   Reduction of RF-Emissions From a Pulsed Electrical Supply Using an Active Gate Control
By H. Holst; H. Jain; T. Thiringer; T. Tuveson [View]
[Download]

Abstract: In this paper a method for reducing the RF-emissions from a PWM operated load is investigated. The idea is to use an active gate control in order to obtain a smooth transition between the upper and lower voltage level. A smooth transition may reduce emissions compared to using a switching with sharp flanks and thus leading to reduced EMI. Few circuits are available on the market, that reduce the slopes, but not with active feedback control. In this study a flexible curve-shaping circuit for adc-dc PWM converter, with active gate control, is developed and investigated. The result found is that the method works well, which is verified experimentally. Different curve shapes have been studied and a comparison between trapezoidal and sinusoidal curves shows that, employment of sinusoidal curve-shape gives lower RF-emission compared to trapzoidal. In addition the switching losses are reduced by 10% for the sinusoidal curve-shape. Finally, the circuit operates in the region of 8-15 V power supply.

   Output Harmonic Losses in Three-level Converters using Sine PWM with 3. Harmonic Injection
By R. Lund; G. Tomta; R. Nilsen [View]
[Download]

Abstract: Analytical expressions for the ripple current on the AC-side of a 3-level converter are developed for sinusoidal PWM with 3. harmonic injection. By using analytical expressions, time consuming time domain simulations are avoided. Experimental measurements on a three-level prototype in the lab and simulations are done to verify the analytical expressions. By introducing a 3. harmonic component in the control signals, an increase in the modulation range of 15% can be achieved. In addition, the harmonic current is lowered, especially in the high modulation range.

NORpie 2004 - Topic 02: Converters
You are here: EPE Documents > 05 - EPE Supported Conference Proceedings > NORpie - Proceedings > NORpie 2004 > NORpie 2004 - Topic 02: Converters
	[return to parent folder]

	Pulse Rectifiers Current-Type for Applications in Modern Frequency Converters By P. Hlisnikovsky; P. Chlebis	[View] [Download]
Abstract: This document occupy with the pulse rectifier current-type as a modern controlled rectifier, which is very suitable as an input unit of indirect frequency converters current-type, because its low emissions of harmonics into the network, the controlled power factor and the controlled current in DC link. There is a comparison between the pulse rectifier and the classical thyristor rectifier. There is a description of the zero current switch pulse rectifier as suitable input unit of indirect frequency converter current-type with the series resonant DC-link. The vector pulse width modulation and the delta modulation as the suitable control methods for the pulse rectifiers or for the whole frequency converter are also described in the contribution. The measured results on the realized physical models are enclosed at the end of the contribution.

	Paralleled three-phase inverters By E. Hoff; T. Skjellnes; L. Norum	[View] [Download]
Abstract: Paralleling of inverters are useful for a number of reasons, where modularity and redundancy are some of the key points. Load sharing and voltage control may be done using different methods. The three-phase voltage is controlled by either using fixed frame, áâ-coordinates, or synchronized frame, dqcoordinates. Models for the dynamic behavior of paralleled inverters will be investigated through Matlab Simulink simulations.

	Dimensioning of a Current Source Inverter for the Feed-in of Electrical Energy from Fuel Cells to the Mains By M. Mohr; M. Bierhoff; F.W. Fuchs	[View] [Download]
Abstract: Fuel cells deliver dc current which demands a dc/ac converter between the fuel cell and the mains to feed in electrical energy. An inverter of the current source type makes it possible to convert the energy supplied by a fuel cell into the mains without using an auxiliary dc/dc-converter. The current source inverter’s efficiency depends on the input dc voltage of the inverter, so the rating of the fuel cell voltage influences the overall efficiency of the system. After a short introduction of the fuel cell’s electrical behaviour, the current source inverter and the impact of its LCFilter on the inverter’s input voltage are described. The dimensioning process dependent on the power range of the fuel cell and the current source inverter is shown. In doing so, the characteristics of the fuel cell and the inverter are taken into account. A laboratory setup of a current source inverter has been built and a control scheme is presented. Simulation results of the general system behaviour are shown.

	Comparison of commutation transients of inverters with silicon carbide JFETs with and without body diodes By B. Allebrand; H.-P. Nee	[View] [Download]
Abstract: An inverter could be built by using silcon carbide power switches only. This can be done by using SiC JFETs which can conduct current in both directions. An interesting question is how an inverter using SiC JFETs with a body diode compares with an inverter using SiC JFETs without body diodes. This will be discussed in this paper.

	Power device selection and a comparative study of transistor technologies for a Zero Voltage Switching Buck Converter By P. Andreassen; T. Undeland	[View] [Download]
Abstract: The new ultra thin wafer technology makes it possible to make Non Punch Through (NPT) IGBTs in the 600V range, with a lightly doped collector. This new IGBT technology is tested and compared with other competitive transistor technologies. The case study of the Zero Voltage Switching (ZVS) Buck Converter is performed because this topology until now has favored the use of MOSFETs.

	A Systematic Approach to Analyze the Stability of Distributed Power Supply Systems By A. Hentunen; K. Zenger; T. Suntio	[View] [Download]
Abstract: A systematic approach is presented to analyze the stability of distributed power supply systems. In this paper, unterminated modeling technique is applied to obtain a transfer function model between the inputs and outputs of a distributed power supply system. This transfer function model allows us to study bounded-input-bounded-output stability.

	Synchronous Communication Link for IGBT Gate Driver Units By T. Kjellqvist	[View] [Download]
Abstract: New inverter topologies and series connection of IGBTs require more intelligent gate drivers and faster communication links. Also, higher voltages require better electrical insulation and the communication distance increase. Most gate diver units utilize some kind of asynchronous communication protocol where the length of the pulse is varied to distinguish between different symbols on the link. The communication protocol is easily implemented in discrete logic. Using a synchronous protocol allow for an increased number of messages and a shorter latency since timing is improved compared to any asynchronous protocol. Alternatively, system frequency can be reduced and thereby reducing power consumption. In some applications programmable logic is already present due to the need of sophisticated control of the device and more complex communication protocol can be implemented with a limited amount of extra hardware. The link can easily be used for low speed communication in parallel to the modulation signaling. This low speed channel can be used for configuration of the gate driver or communicating chip temperature to the modulator.

	Reduction of RF-Emissions From a Pulsed Electrical Supply Using an Active Gate Control By H. Holst; H. Jain; T. Thiringer; T. Tuveson	[View] [Download]
Abstract: In this paper a method for reducing the RF-emissions from a PWM operated load is investigated. The idea is to use an active gate control in order to obtain a smooth transition between the upper and lower voltage level. A smooth transition may reduce emissions compared to using a switching with sharp flanks and thus leading to reduced EMI. Few circuits are available on the market, that reduce the slopes, but not with active feedback control. In this study a flexible curve-shaping circuit for adc-dc PWM converter, with active gate control, is developed and investigated. The result found is that the method works well, which is verified experimentally. Different curve shapes have been studied and a comparison between trapezoidal and sinusoidal curves shows that, employment of sinusoidal curve-shape gives lower RF-emission compared to trapzoidal. In addition the switching losses are reduced by 10% for the sinusoidal curve-shape. Finally, the circuit operates in the region of 8-15 V power supply.

	Output Harmonic Losses in Three-level Converters using Sine PWM with 3. Harmonic Injection By R. Lund; G. Tomta; R. Nilsen	[View] [Download]
Abstract: Analytical expressions for the ripple current on the AC-side of a 3-level converter are developed for sinusoidal PWM with 3. harmonic injection. By using analytical expressions, time consuming time domain simulations are avoided. Experimental measurements on a three-level prototype in the lab and simulations are done to verify the analytical expressions. By introducing a 3. harmonic component in the control signals, an increase in the modulation range of 15% can be achieved. In addition, the harmonic current is lowered, especially in the high modulation range.