Paper Presentations

High Power UPS Achieves Significant Size and Weight Reduction While Increasing Performance
George Oughton, Eaton Corp

A new transformerless topology is presented. Eliminating utility frequency magnetics allows the high power, 3 phase UPS (Uninterruptible Power Supply) to achieve significant weight and size reduction and improve performance values for the customer. A high input power factor and low input current harmonics over a wide line and load range help to avoid oversizing a companion generator. A wide battery voltage range allows use with more existing battery banks. An output power capability up to 90% of rated KVA better supports modern power factor corrected loads. An optimized high frequency inductor design approach has complemented this topology without compromising the advances in size, weight, efficiency and cost effectiveness.

This paper describes the basic elements of the topology and design approach that enabled this next step forward in power protection value.

Digital Electronics and Controls for Uninterruptible Power Supplies
Dr. Silvio Colombi, General Electric

Reliability, performance and cost are key features in the UPS market. Today, advances in microelectronics, power semiconductors, energy storage systems and power converter topologies influence these features. In particular, with a hardware cost reduction of 30% per year and a computing power doubling every 6 months, it is more and more interesting to realize UPS features and functions in a digital way. In addition, the software costs nothing in production and the digital world opens the way to preventative maintenance, advanced diagnostics and improved connectivity. This paper is an overview of several original developments realized at GE-Digital Energy and based on a Digital Signal Processor platform. Topics include: control strategies for UPSs with/without output transformers, Active Filters, variants of Space Vector Modulation, Economy Mode to increase efficiency, Modulations & Topologies for Boost Rectifiers, Intelligent Synchronization Module to allow multiple Power Quality architectures, Mains Paralleling Capability, Preventative Maintenance and Advanced diagnostics.

Achieving High Efficiency in a Double Conversion UPS While Using an IGBT PWM Rectifier
John Tracy, Eaton, Powerware Products

This paper describes the design of a double conversion UPS that uses two high frequency PWM power converters in series without sacrificing efficiency compared to its forerunner using an SCR type rectifier. The advantages of using a high frequency PWM converter for the AC-to-DC stage are generally well known: Improved input power factor; Improved input current THD; and Improved performance on a generator. It has long been accepted, however, that a high frequency PWM converter will have higher losses than a diode rectifier or SCR phase control rectifier and that the loss in efficiency is simply one way to bare the cost for the increased performance. This paper presents, as a case study, how one UPS design addressed the efficiency issue and produced a product that controlled the losses and achieved efficiency equal to or better than the SCR forerunner.