Power Supply Scheme Research Articles

Power Supplies and Quench Protection for the Tokamak Physics Experiment

The Tokamak Physics Experiment (TPX) is an advanced tokamak project aimed at the production of quasi-steady state plasmas with advanced shape, heating, and particle control. TPX is to be built at the Princeton Plasma Physics Laboratory (PPPL) using many of the facilities from the Tokamak Fusion Test Reactor (TFTR). First plasma is scheduled for the year 2000.TPX will be the first tokamak to utilize superconducting (SC) magnets in both the toroidal field (TF) and poloidal field (PF) systems. This is a new feature which requires not only a departure from the traditional tokamak power supply schemes but also that ultra-reliable quench protection devices be used to rapidly discharge the stored energy from the magnets in the event of a quench.This paper describes the plan and basis for the adaptation and augmentation of the PPPL/TFTR power system facilities to supply TPX. Following a description of the basic operational requirements, four major areas are addressed, namely the AC power system, the TF power supply, the PF power supply, and quench protection for the TF and PF systems.

Circuit techniques for 1.5-3.6-V battery-operated 64-Mb DRAM

Circuit techniques for battery-operated DRAMs which cover supply voltages from 1.5 to 3.6 V (universal V/sub cc/), as well as their applications to an experimental 64-Mb DRAM, are presented. The universal-V/sub cc/ DRAM concept features a low-voltage (1.5 V) DRAM core and an on-chip power supply unit optimized for the operation of the DRAM. A circuit technique for oxide-stress relaxation is proposed to improve high-voltage sustaining characteristics while only scaled MOSFETs are used in the entire chip. This technique increases sustaining voltage by about 1.5 V compared with conventional circuits and allows scaled MOSFETs to be used for the circuits, which can be operated from an external V/sub cc/ of up to 4 V. A two-way power supply scheme is proposed to suppress the internal voltage fluctuation within 10% when the DRAM is operated from external power supply voltages ranging from 1.5 to 3.6 V. An experimental 1.5-3.6-V 64-Mb DRAM is designed based on these techniques and fabricated by using 0.3- mu m electron-beam lithography. An almost constant access time of 70 ns is obtained. This indicates that battery operation is a promising target for future DRAMs.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A novel power MOSFET switching-mode power supply

Increasingly, the operating frequency of switched-mode power supplies (SMPS) eliminates the need for bulky magnetic and output filter components, thereby reducing their overall weight and volume. Power MOSFETs, which are capable of operating at much higher frequencies than those achievable with present-day bipolar transistors, have by now established their credibility in switching-mode power supply applications. In the paper, a fundamentally different scheme of switched-mode power supply, in which the transformer demagnetizing winding (clamping winding) is eliminated by using a simple RC clamping circuit, is discussed. It is shown that this scheme is capable of delivering a steady DC output voltage, under a much wider variation of DC source voltage.

Six Phase Synchronous Machine with AC and DC Stator Connections, Part II: Harmonic Studies and a Proposed Uninterruptible Power Supply Scheme

The relationships of the mutual leakage inductances with winding displacement angle and pitch for a number of practical six phase winding configurations are derived. The voltage harmonic distortion and torque pulsation of a six phase machine with AC-DC stator connections are characterized in terms of the operating load conditions, winding displacement angle, pitch, converter commutating reactance, and rotor impedance. It is shown that for most operating conditions a displacement angle of 300 appears to be optimum with respect to voltage harmonic distortion and torque pulsation. The effects of neglecting the mutual leakage coupling on the voltage harmonic distortion, torque pulsation and transient characteristics of the machine are examined. A novel application of the six phase machine in an uninterruptible power supply scheme is proposed. Results on the dynamic performance of the proposed UPS scheme to input voltage spikes and to a normal supply interruption are included.

Six-Phase Synchronous Machine with ac and dc Stator Connections, Part II: Harmonic Studies and a Proposed Uninterruptible Power Supply Scheme

Six-Phase Synchronous Machine with ac and dc Stator Connections, Part II: Harmonic Studies and a Proposed Uninterruptible Power Supply Scheme

The Application of Statistical Reliability Data in the Selection of a Utility Power Supply Scheme for an Industrial Plant

A detailed analysis was made to determine the most economical electrical utility supply configuration to serve a new polyester manufacturing facility. The basis used for the analysis centered around: a) IEEE survey reliability data and IEEE statistical reliability techniques, b) historical outage cost data from the three existing manufacturing facilities, and c) an estimated power restoration curve developed by the facilities maintenance department. Explicit definitions were developed to define what power outages meant for the various types of loads to be served. The minimum total yearly cost, made up of yearly facilities' cost plus yearly outage cost was used to identify the most economical configuration.

A superconducting synchrotron power supply and quench protection scheme

The power supply and quench protection scheme for the proposed Fermilab 6 km circumference superconducting synchrotron is described. Specifically, the following points will be discussed: 1, the 46 MW thyristor power supply; 2, the 3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> joule emergency energy dump; 3, the distributed microprocessing system for the detection of quenches; 4, the thyristor network for shunting current around quenched magnets; and 5, the heaters internal to the magnets which cause rapid propagation of quenches. Test results on prototype systems are given.

Thrust and levitation force of linear synchronous motors for propulsion and levitation use

A generalized analytic model has been proposed for the vertical ground-coil-type linear synchronous motor for propulsion and levitaton use. Mathematical expressions have been derived for calculating its thrust and levitation force characteristics. The thrust and levitation force characteristics of the motor have been analyzed assuming various waveforms of ground coil current and magnetic flux. As a result of this analysis, it has been made clear that the waveforms of magnetic flux and ground coil current have a great effect on the thrust and levitation force characteristics. Waveforms of ground-coil current and magnetic flux should be determined taking into account many factors, such as the electric power supply scheme, power conversion scheme, running characteristics of train, etc. The proposed linear synchronous motor is more suited for high-speed trains than for the low-speed trains. In the low-speed region, it is recommended to drive and suspend the train by means of different devices.