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Four Bipolar-FET combinational transistor configurations are compared from the application point of view. The configurations included are FET-Darlington (Cascade), Emitter-Open Switch (Cascode), Parallel Configurations and FET-Gated Bipolar Transistors (FGT).
Concerning a multi-output DC power supply having two or more secondary windings it was an important technical problem that the main switch would easily become a heat spot. The heat spot is predominantly caused by the power loss which occurs at the transient time. This paper describes a new circuitry and its control method that help dramatically improve the operation trajectory of the main switch and...
A model to evaluate power MOSFET switching loss is developed. Frequency dependencies are measured using a one-transistor forward converter and compared with calculated ones. For comparison, maximum output powers are measured both for power MOSFETs and bipolar transistors. To reduce the switching loss and enable a faster switching a small feedback capacitance device is proposed and realized.
This paper deals with new uninterruptible power supply (UPS) system for satellite communication, delivered to Kokusai Denshin Denwa Co., Ltd. Sophisticated operation and transfer techniques of the system consisting of two UPS units and two bypass units to improve system availability are described. Microcomputerized 150 kVA GTO UPS unit which provides excellent characteristics, waveform recording and...
After a brief analysis of the power requirements of various telecommunication AC load this paper describes some different uninterruptible power plants presently adopted and compares them from the point of view of performances and reliability. It is then presented a type of uninterruptible AC power plant installed in many SIP (Italian Operating Telephone Company) exchange officies. It is characterized...
The switching power supply conversion frequency has been raised annually as switching power supplies have become more compact and light. To realize high frequency power supply, circuit component frequency must also be raised and switching transistors are required to have a high-speed switching and large safe operating area. Previously, a high-speed switch was assumed to be incompatible with a large...
This paper describes the measures of improvement in efficiency in single-ended forward switching power supply (SPS) having dimensions smaller than conventional ones, especially narrower in width. As a result, a 5V 50W SPS with 60% volume and approximately 50% weight compared to conventional SPS has been improved while increasing efficiency up to 80% with respect to the 75% efficiency of conventional...
A case study is described of a telecommunications system wherein the utilization of power was given serious consideration from the point of inception. The objective was to determine the power processing architecture that optimized such figures of merit as efficiency, life cycle cost, first cost and reliability without imposing any of the traditional constraints that result from initiating powering-system...
The charging methods for stationary accumulators for use in telecommunication installations have changed through out the years. The reason for this is not only the development and the achievements in the battery technology field and the new methods and components in the control area but also the better knowledge of demands and result of the operation and maintenance work in the field. From the administrations...
The power plant of the telecommunications center plays an important role in the telecommunications facilities from the view point of reliability and energy conservation. KDD (Kokusai Denshin Denwa Co., Ltd.) is now constructing the new international switching center. This paper describes the power system of this new switching center where an effort has been made to have the power system more reliable...
A survey on the state of the arts in the dc-to-dc converter is presented. A number of important problems underlying the converter are classified into two categories, one is solvable by the averaging method and the other is not. In general, the converter circuit itself should be stable in order to reduce the size of the converter by making its switching frequency high. As examples of size reduction,...
This paper describes some transient and steady-state characteristics of a center-tapped high-frequency inverter using ASCR, which is capable of operating at 80 KHz. In the first place, the basic operation of the inverter is discussed and then the normalized numerical solution is elucidated. Effects of inductance ratio and capacitance ratio on the steady-state characteristics for the inverter are fully...
Energy storage and power processing with magnetic devices is more efficient if the separate inductors and transformers are integrated into a single magnetic structure. The origins and main results of the coupled-inductor and integrated magnetics concepts are reviewed.
A small size DC-DC regulated converter which does not include inductance is descrived. Voltage transformation is achieved by switched capacitors, that is charging capacitors in series and discharging them in parallel or charging them in parallel and discharging them in series. In the case of inverting the polarity of output voltage, the capacitors are connected to the load as the polarity is inverted...
This paper describes technologies applied to the power pack for the NTT Digital Local Switching System. To introduce a new physical design into the system, small size, low noise and maintenance free power packs have been required, aiming at setting them in each small sized equipment module, which includes many LSIs. To meet the requirement, the power pack is designed by following advanced technologies...
This paper explains the design approach taken for heating and cooling an unmanned container hut, which contains electronic local switching equipment, to maintain the container hut air temperature and relative humidity within a given range. Electronic switch reliability is assured. A new small air-cooled package airconditioner, which has both a refrigerant cycle with a compressor and a thermosiphon...
This paper describes a new line of utility frequency UPS designed for modern data communications and processing applications. Emphasis has been given to high reliability by the use of a simple new power switching circuit which is discussed. Very high efficiency is achieved by the use of new high voltage transistor switches which are illustrated. Problems and solutions using these switches in this...
This paper reviews the forces and trends that have an impact on the evolution of exchange telecommunication networks and the effect each of these may have on central-office power systems. Alternative powering architectures are discussed, with considerations highlighted for each. No prediction is made as to which of the power architectures will dominate; this will depend on the evolution of various...
A general purpose control and monitoring system for power plants has been developed by ERICSSON, Sweden. Based on distributed microcomputers the system is implementable not only in Power Supply Plants but also in the other systems involved in generation conversion, storage and transportation of energy in conjunction with a telecommunication plant. The system has been named ERICSSON ENERGY-MASTER and...
This paper describes a three-phase rectifier using an energy-constant modulation technique. The rectifier with this method has three converters and is controlled by the pulse width modulation as the instantaneous energy flow through the rectifier is constant. A new control method of reducing the influence of the storage time of the switching elements is proposed. The data of the experimental rectifier...
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