EPE Association: EPE 2003 - Topic 08a: Uninterruptible Power Supplies (UPS)

EPE 2003 - Topic 08a: Uninterruptible Power Supplies (UPS)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2003 - Conference > EPE 2003 - Topic 08: POWER SUPPLIES > EPE 2003 - Topic 08a: Uninterruptible Power Supplies (UPS)

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   Improving the inverter reliability through the use of a cost-effective and temperature independant DC voltage sensor
By P. Zajec; J. Nastran; D. Voncina [View]
[Download]

Abstract: The paper deals with detection and reduction of the parasitic DC component in the output voltage of the DC/AC inverter. A simple and cost-effective sensor based on the detection of differential transformer pre-magnetisation is proposed. Besides its excellent DC sensitivity, the sensor features also small temperature independence in contrast to solutions relying on Hall sensor use.

   Inverter with soft switched transistors for Uninterruptible Power Supplies
By F. Renken [View]
[Download]

Abstract: The use of soft switching inverters in static uninterruptible power supplies is being examined. At first complete UPS-systems with insulation transformer as well as without transformer are described. The different inverter topologies of these systems are shown and the characteristics of the inverters are presented. Several soft switching inverters for that application are analysed and evaluated. At last inverter with hard and soft-switched transistors are compared with each other based on measurements.

   A new approach to battery management systems
By J. Chatzakis; K. Kalaitzakis; N. C. Voulgaris; S. Manias [View]
[Download]

Abstract: The existing Battery Management System (BMS) techniques are examined in this paper and a new design methodology for a reliable BMS is proposed. The main advantage of the proposed BMS compared to the existing systems is that it provides a fault-tolerant capability and battery protection.

   A novel static and dynamic droop scheme to enhance transient response in parallel-connected UPS inverters
By J. M. Guerrero; L. García de Vicuña; J. Matas; J. Miret; J. Majó [View]
[Download]

Abstract: In this paper, a new controller for parallel-connected UPS inverters is presented. The proposed controller is based on the droop method in order to avoid the use communication signals between the modules. The paper deals to study the dynamic response limitations of the conventional droop method. As a consequence, we propose a novel control scheme to overcome these limitations, endowing to the paralleled UPS: fast transient response, excellent power sharing, and low output voltage THD when supplying nonlinear loads.

   Parallel operated three-phase UPS systems with inrush current suppression and cross current control loops
By S. Nishikata; M. Omura; T. Kataoka [View]
[Download]

Abstract: Transient performances of three-phase UPS systems connected in parallel are discussed for the case when a load of capacitor-filtered rectifier is connected to the system. Inrush output current can be greatly reduced when digital control with inrush current suppression loop and parallel running controller in addition to observer, voltage drop compensator and PID controller is applied to the system. Transient responses of UPS output voltage, load current and cross current when the load is connected are examined, and the validity of the proposed control is confirmed through experimental investigations.

   Demonstration of an ultracapacitor-based UPS
By F. Ferrandis; T. D. Geist [View]
[Download]

Abstract: IBERDROLA, EPRIww, and EPRI PEAC are working together on a field demonstration of an emerging technology (asymmetrical ultracapacitors) that can replace commonly used lead-acid batteries in critical applications requiring uninterrupted power. The ultracapacitor-based UPS is capable of protecting commercial loads such as computers and cash registers from the impact of short-term voltage disturbances and outages lasting over five minutes. The system components were integrated and tested in the EPRI-PEAC laboratory in Knoxville, Tennessee, USA. Once the laboratory-testing was completed, the system was shipped to a supermarket operated by MERCADONA, one of the most important Spanish Distribution Companies, in Llara, Valencia, Spain. The system was installed and will remain for six months to demonstrate and document the ability of the ultracapacitor UPS to protect equipment from power disturbances. This is one of the first applications of asymmetrical ultracapacitors for UPS systems in commercial sites.

   Development of coupling elements in bidirectional UPS
By K.F. Hoffmann; J. Schmidt; H. Güldner [View]
[Download]

Abstract: The line inductance of a conventional bidirectional UPS can be replaced by different kinds of high frequency switching AC/AC converters, which results in improved efficiency, a high input-power-factor and a reduction in weight. In this paper the different coupling elements between mains and inverter are divided into three fundamental groups and an ”ideal” bidirectional UPS is defined. Furthermore selected coupling elements from each group are analysed and discussed in detail. Moreover this article points out the significant advantages of converter-coupled bidirectional UPS.

EPE 2003 - Topic 08a: Uninterruptible Power Supplies (UPS)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2003 - Conference > EPE 2003 - Topic 08: POWER SUPPLIES > EPE 2003 - Topic 08a: Uninterruptible Power Supplies (UPS)
	[return to parent folder]

	Improving the inverter reliability through the use of a cost-effective and temperature independant DC voltage sensor By P. Zajec; J. Nastran; D. Voncina	[View] [Download]
Abstract: The paper deals with detection and reduction of the parasitic DC component in the output voltage of the DC/AC inverter. A simple and cost-effective sensor based on the detection of differential transformer pre-magnetisation is proposed. Besides its excellent DC sensitivity, the sensor features also small temperature independence in contrast to solutions relying on Hall sensor use.

	Inverter with soft switched transistors for Uninterruptible Power Supplies By F. Renken	[View] [Download]
Abstract: The use of soft switching inverters in static uninterruptible power supplies is being examined. At first complete UPS-systems with insulation transformer as well as without transformer are described. The different inverter topologies of these systems are shown and the characteristics of the inverters are presented. Several soft switching inverters for that application are analysed and evaluated. At last inverter with hard and soft-switched transistors are compared with each other based on measurements.

	A new approach to battery management systems By J. Chatzakis; K. Kalaitzakis; N. C. Voulgaris; S. Manias	[View] [Download]
Abstract: The existing Battery Management System (BMS) techniques are examined in this paper and a new design methodology for a reliable BMS is proposed. The main advantage of the proposed BMS compared to the existing systems is that it provides a fault-tolerant capability and battery protection.

	A novel static and dynamic droop scheme to enhance transient response in parallel-connected UPS inverters By J. M. Guerrero; L. García de Vicuña; J. Matas; J. Miret; J. Majó	[View] [Download]
Abstract: In this paper, a new controller for parallel-connected UPS inverters is presented. The proposed controller is based on the droop method in order to avoid the use communication signals between the modules. The paper deals to study the dynamic response limitations of the conventional droop method. As a consequence, we propose a novel control scheme to overcome these limitations, endowing to the paralleled UPS: fast transient response, excellent power sharing, and low output voltage THD when supplying nonlinear loads.

	Parallel operated three-phase UPS systems with inrush current suppression and cross current control loops By S. Nishikata; M. Omura; T. Kataoka	[View] [Download]
Abstract: Transient performances of three-phase UPS systems connected in parallel are discussed for the case when a load of capacitor-filtered rectifier is connected to the system. Inrush output current can be greatly reduced when digital control with inrush current suppression loop and parallel running controller in addition to observer, voltage drop compensator and PID controller is applied to the system. Transient responses of UPS output voltage, load current and cross current when the load is connected are examined, and the validity of the proposed control is confirmed through experimental investigations.

	Demonstration of an ultracapacitor-based UPS By F. Ferrandis; T. D. Geist	[View] [Download]
Abstract: IBERDROLA, EPRIww, and EPRI PEAC are working together on a field demonstration of an emerging technology (asymmetrical ultracapacitors) that can replace commonly used lead-acid batteries in critical applications requiring uninterrupted power. The ultracapacitor-based UPS is capable of protecting commercial loads such as computers and cash registers from the impact of short-term voltage disturbances and outages lasting over five minutes. The system components were integrated and tested in the EPRI-PEAC laboratory in Knoxville, Tennessee, USA. Once the laboratory-testing was completed, the system was shipped to a supermarket operated by MERCADONA, one of the most important Spanish Distribution Companies, in Llara, Valencia, Spain. The system was installed and will remain for six months to demonstrate and document the ability of the ultracapacitor UPS to protect equipment from power disturbances. This is one of the first applications of asymmetrical ultracapacitors for UPS systems in commercial sites.

	Development of coupling elements in bidirectional UPS By K.F. Hoffmann; J. Schmidt; H. Güldner	[View] [Download]
Abstract: The line inductance of a conventional bidirectional UPS can be replaced by different kinds of high frequency switching AC/AC converters, which results in improved efficiency, a high input-power-factor and a reduction in weight. In this paper the different coupling elements between mains and inverter are divided into three fundamental groups and an ”ideal” bidirectional UPS is defined. Furthermore selected coupling elements from each group are analysed and discussed in detail. Moreover this article points out the significant advantages of converter-coupled bidirectional UPS.