Showing papers on "Power module published in 1988"

Power electronics in electric utilities: static VAR compensators

Abstract: The author deals with dynamic VAR compensation of electric power systems, applying power electronics for reactive power generation and control. After an overview of the emergence and status of modern, solid-state VAR compensators in utility and industrial applications, it is shown how dynamic VAR compensation increased transmittable power by providing voltage support, transient stability improvement, and power oscillation damping in electric power transmission systems. Methods of reactive power generation and control using thyristor-controlled reactors, with fixed and thyristor-switched capacitors or modern gate-turn-off (GTO) power converters that can function without AC capacitors or reactors, are described. A summary is included of the control structure and operation to provide the desired characteristics and performance in power systems applications. >

Coupling network for improving conversion efficiency of photovoltaic power source

Abstract: A switching network for improving the conversion efficiency of a photovoltaic power supply comprises a variable coupling circuit for coupling an array of photovoltaic cells to a load resistance. The combined effective impedance of the network and load is varied to match the value required for maximum output power. A switching transistor (22) which connects the source module (20) to the load (30) is pulse-width modulated with a variable duty cycle determined by the control signal from the sensor circuit. A photovoltaic cell (32) similar to those comprising the photovoltaic power module (20) is used to track variations in the ambient light intensity. The open-circuit voltage of a sensor cell (32) is used to determine the proper value of duty cycle required for maximum power transfer. The output voltage of the module (20) is sampled and compared with the proper value to produce a control signal.

Uninterruptible power supply utilizing a synchronized chopper for power factor improvement

Abstract: This invention relates to an uninterruptible power source equipment to rectify a commercial power supply to charge a capacitor through a chopper circuit to a constant voltage, thus to utilize it as a constant voltage power source and to charge a back-up capacitor, thus to deliver a power from the battery to the constant voltage power source when the commercial power source is interrupted. The output of the constant voltage power source may be converted to an a.c. output by the inverter unit. The chopper circuit includes a reactor and a switching element responding to a control signal to effect on-off operation. The control signal is formed as a sine wave signal in phase with the commercial power source. This control signal may be applied to the inverter unit. The UPS equipment allows a sine wave current having a power factor nearly equal to 1 to flow in when the commercial power source is in a normal condition, thereby making it possible to improve the power factor of the power source and to reduce power wave form distortion. In addition, when the commercial power source is in an abnormal condition, a current flowing out from the battery is allowed to become a flat direct current, thus making it possible to utilize the capacity of the battery to the maximum degree. Thus, an economical, small and light control apparatus for UPS can be realized.

Modular switch device

Abstract: A modular switch device includes a housing enclosing an interconnected control module, a display module and a power module. A sensor module supplying analog data signals from one of a temperature or pressure sensing element connects to the control module through a passage in the housing. A user connects his electrical wires and electrical power to the electrical assembly within the housing through an opening. The user can select between AC and DC switched output modules and the presence or absence of a 4-20 milliampere output module by plugging and unplugging same from wells provided in the housing. The manufacturer and user thus can modify the standard housing, which includes an internal electrical assembly to be a pressure or temperature switch and to provide selected output switch characteristics by applying and removing selected sensor and output modules thereto. The interconnection between the sensor module and the control module includes particular leads carrying analog data signals and serial digital information signals. The control module includes one analog to digital converter and control means in the form of a microprocessor.

Evolution of MOS-bipolar power semiconductor technology

Abstract: A review of the innovations that have led to the evolution of a power transistor technology based on MOS gate control is provided. This technology offers the advantage of very high input impedance, which allows the control of the devices using low-cost integrated circuits. The physics of operation of the two types of devices in this category, power MOSFETs and power MOS-bipolar devices, are described. Trends in process technology and device ratings are analyzed. Based on the superior performance of these devices, it is projected that they will completely displace the power bipolar transistor in the future. >

Self-sustaining power module

Abstract: A self-sustaining power module (10) that combines the technologies of radioactivity with photovoltaic cells (12) to produce an electrical power supply having a useful life of over ten years. The radioactive source is a tritium capsule (22) that interfaces with the receptor surface of the photovoltaic cell (12). The capsule (22) has inside surfaces that are coated with a phosphor and is filled with tritium gas (26). The tritium gas produces beta particles that bombard the phosphor (18) causing the phosphor to luminesce and produce photons. The photons, in turn, strike and cause the photovoltaic cell (12) to generate a current flow that is then applied, via a pair of electrtodes (30), (32), to an external load. Also disclosed is a power pack (40) that houses a plurality of power modules (10). The power pack includes provisions that allow the power modules (10) to be electrically interconnected to provide various series, parallel and series-parallel power output combinations.

Power supply for cathodic protection system

Abstract: A power module for a cathodic protection system is provided having a switch-mode power circuit and a synchronous switch assembly. The method of the invention comprises rectifying an alternating utility power signal with a power transformer and switch assembly. The switch assembly is controlled by a phase control circuit to provide a selective controlled phase delay to provide a 0-100% range power signal to the load selectively operable in a constant current, constant voltage or off-potential manner.

Phase-staggering control of a series-resonant DC-DC converter with paralleled power modules

Abstract: A method of decreasing the ripple on the output voltage of high-power AC-DC or DC-DC series-resonant converters without increasing the internal converter frequency or the capacity of the energy storage elements is discussed. This improvement is accomplished by subdividing the converter into two or more series-resonant power modules operated with a constant relative phase shift (phase-staggering control). The method of eliminating the harmonic components in the input and output currents of the conversion system, without increasing the internal pulse frequency, is justified by Fourier analysis of the current waveforms. The frequency spectra of the source and output waveforms for the continuous and discontinuous resonant current mode are shifted to higher frequency ranges, as computations show for both one single module and multiple paralleled modules. Inadequacies in the phase-staggering control method applied to series-resonant converters are indicated in relation to the dominant harmonic component, in particular for two modules and supported by experimentally acquired waveforms. High-frequency current components to the source and to the load are reduced. Resulting in smaller input and output filters. This improves the resolution of the control of the flow of energy from the source to the load, resulting in a faster system response. >

Intrinsic safety module interface

Abstract: An interface system interconnects a common power supply and plural data communications paths located in a safe environment to a plurality of load devices located in a flammable atmosphere. A module power attenuator attenuates the electrical power output level of the common power supply to a first predetermined level for application to the load devices. A digital signal attenuator attenuates the electrical power level between data communications paths to a second predetermined level for application to the load devices. Coupling devices are utilized to maintain electrical segregation but allow communication to and from the safe environment.

Life after the schematic: the impact of circuit operation on the physical realization of electronic power supplies

Abstract: The impact of the nonlinear analog operation of power electronic circuits on the physical realization process is considered. Portions of the physical realization process of a switched-mode power supply are compared with those of a digital circuit board assembly of exactly the same size and power dissipation. This comparison serves as an illustrative example of how differences in circuit operation prevent power supply engineers from using many of the design methodologies that are so effective in digital applications. >

Power semiconductor devices: an overview

Abstract: Advances in power semiconductor devices are discussed, focusing on the adaptation of silicon integrated circuit wafer processing methods to the design and fabrication of power devices. Some basic properties of power devices are reviewed, along with recent adaptations of wafer processing technology. Two trends are discerned: increasing use of self-aligned, double diffused MOS gate structures to achieve devices with low-current drive requirements; and movement toward an ideal one-dimensional device, thereby making more efficient use of the available area. Different devices are compared. Techniques that have potential for use in power device are discussed: use of trenches, direct wafer bonding, cellular bipolar transistors, and junction termination. The combination of power switches with control logic on the same chip is briefly considered. >

AC to DC solid state power supply using high frequency pulsed power switching

Abstract: A highly innovative new technique of developing AC to DC power sources for various applications has been described. Such technique of generating DC power is different from the conventional linear and switching power conversion techniques and this new technology has been called the Solid State Power Supply (SSPS) Technology. The principle of operation depends upon high-frequency pulsed power switching followed by high energy charge-discharge principles as applied to power conversion technology. The use of fast turn-on power MOSFETs enables the application of high frequency switching on this power technology. While the non-isolated SSPS is claimed to be transformerless, the isolated SSPS requires the use of a transformer for input-output isolation. The input and output filtering is reduced tremendously, thereby reducing the size of such power supplies. The SSPS technology is expected to revolutionize the 50/60/400 Hz power conversion technology and a compactness as much as 4:1 over the current 50KHz switching power supply is possible.

Reliability analysis of a direct parallel connected n+1 redundant power system based on highly reliable DC/DC modules

Abstract: An n+1 redundant system using modular hybrid DC/DC converters connected in parallel where the normally associated isolation diodes are omitted is described. Reliability and efficiency analysis of the systems was performed, based on a comparison between the system described and a system based on a conventional (uninterruptible power system) UPS with added redundant functions. It is concluded that the proposed approach will lead to an improvement in overall efficiency and result in compact, cost-effective systems. >

Powered microwave oven

Abstract: A microwave oven is described suitable for use on transports where DC power is available. The microwave oven employs a first inverter to generate internal AC power that is then used to operate the microwave components other than the magnetron microwave source. The internal AC power is passed with relatively low current through the oven interlocks to activate and drive a power inverter that, through an additional output transformer winding, delivers high voltage power to the magnetron. In a preferred embodiment a relay, that is connected to sense when external AC power is available, causes an automatic switching that decouples the internal AC power from the power inverter to enable conventional operation from external AC line power. When external AC line power is no longer applied, the microwave oven automatically switches to operate from the available DC power.

Design for a highly efficient distributed power supply system based on reliability analysis

Abstract: A distributed power supply system with highly efficient characteristics is being developed to replace conventional centralized power systems. In this system, as in conventional power systems, a standby energy system composed of batteries and engine-generator sets is used as a back-up system for the commercial power lines. However, the distributed power system, except for the engine-generator set, is installed in the telecommunications room. Thus, the floor load limitation is an important design factor. Reliability analyses show that the distributed power system should be designed using a fully duplicated engine-generator set; with battery reserve time reduced to one-sixth that of conventional centralized power systems; and with transfer switch unavailability designed to be less than 5*10/sup -7/. >

Power module for motor vehicle fittings

Abstract: The invention relates to a power module, comprising a printed circuit (1, 16) rigidly attached onto a heat sink (2, 17) on which are deposited one or more power silicon chips (10, 25) by directly soldering or bonding so as to enable heat to be removed and distributed between the various chips (10, 25), the electrical linkage between the various output ranges (7, 9) of the silicon chips (10, 25) and the connections being carried out by ultrasonic soldering of an aluminium wire between the output ranges (7, 9) of the silicon chips (10, 25) themselves and the printed circuit (1, 16) which thus enables the current to pass to a connector (13) connected directly to the latter. The module according to the invention is characterised in that the heat sink part (2) on which the silicon chips (10) are mounted comprises extruded parts (4, 5) enabling it to provide its own linkage with the printed circuit (1). Application to the motor vehicle industry.

Determination of thermal cross-coupling effects in mufti-idevice power electronic modules

Abstract: A dynamic thermal model is developed for a 350A half bridge IGBT module and cooler which includes the effects of thermal cross-coupling between the various semiconductor elements. The parameters for the model are extracted from measurements of the transient thermal impedance from junction to ambient. A matrix representation of the model is developed which in turn is implemented into a working model in PSpice by use of a multi-term R-C network. Simulation results show that the cross-coupling effects during load power cycling are not negligible and are dependent on the load power frequency. It is concluded that typical thermal models derived from manufacturers' data may significantly underestimate junction temperature elevation in multi-device power modules.

Poynting vector probe for measuring power at extremely low power factor

Abstract: The paper describes a new probe for the measurement of power flow from a source of supply to a load which is characterised by having an extremely low power factor. Power is measured by sensing the electric and magnetic fields in a defined region between the source and the load. A co-axial configuration is chosen to simplify the integration of the Poynting vector that represents the rate of flow of electromagnetic energy. This leads to a simple design that enables the measurement of voltage and current by sensing the corresponding electric and magnetic fields in an integrated structure incorporating both sensors. The new probe is particularly suitable for the measurement of load losses in large, high-voltage power transformers and shunt reactors in which the power factor is extremely low. A small experimental unit is described, together with the associated electronic circuit.

The Solar Dynamic radiator with a historical perspective

Abstract: A historical perspective on pumped-fluid loop space radiators provides a basis for the design of the Space Station Solar Dynamic (SD) power module radiator. SD power modules, capable of generating 25 kW (electrical) each, are planned for growth in Station power requirements. The Brayton cycle SD module configuration incorporates a pumped-fluid loop radiator that must reject up to 99 kW (thermal). The thermal/hydraulic design conditions in combination with required radiator orientation and packaging envelope form a unique set of constraints as compared to previous pumped-fluid loop radiator systems. Nevertheless, past program successes have demonstrated a technology base that can be applied to the SD radiator development program to ensure a low risk, low cost system.

Rotary power module construction

Abstract: A rotary power module construction especially useful in computer room application. A motor-generator set consisting of an induction motor and synchronous generator is mounted vertically and a direct drive is provided between the components by an electrically insulating coupling. A flywheel is mounted on a shaft of the synchronous generator to provide a maximum ride through condition for short term power outages. A plurality of spider-like leg members envelop the flywheel providing retainment protection for the flywheel as well as providing a suitable support for the synchronous generator. The spider-like leg members are anchored to a plate member which is secured to a non-rotating part of the induction motor. The motor-generator set is encased within a housing that is serviced only from the front of the housing, thereby occupying a minimum amount of space in the computer room. A microprocessor controlled bypass is available to ensure the supply of commerical power to the computer room in the event of an overload or abnormal condition in the motor-generator set.

A bi-directional AC-DC power converter for fixed polarity DC loads

Abstract: Semiconductor power modules which include both transistors and diodes are extensively used for variable frequency inverters feeding motors, and they can also be used for the supply-side converter, providing rectification via the diodes and inversion via the transistors. The drawbacks are their cost, and supply waveform disturbances caused by transistor switching which is essential to the control of the inversion process. The use of an autotransformer (operating at supply frequency) to correct the voltage mismatch is possible but unattractive in terms of cost, and especially bulk. Other solutions, involving the isolation of the diode bridge during inversion by means of series transistors or thyristors, are possible, but involve transitional difficulties when power flow reverses. The authors describe a circuit which aims to solve these problems in an economical way involving minimum bulk and maximum controllability both in steady state and during transient operation. >

Power supply for electronic devices, in particular for safety-related devices in motor vehicles

Abstract: In a power supply for electronic devices, in particular for safety-related devices in motor vehicles, a separate power circuit (21) is provided for groups of electronic devices (23, 27, 31) or for each electronic device (23, 27, 31).

Optimization of an optically pulsed photocell array as a sensor power source

Abstract: A method for improving the efficiency of the conversion of pulsed optical power to electrical power by photovoltaic cells is presented. A fiber-optic echo sensor being developed requires a pulsed power source with a storage capacitor to hold energy for a time after the optical power is turned off. By charging capacitors from each cell individually with a switching transistor control, a higher efficiency is obtained than when the common method of series charging is used. >

Resonant power supplies for a rapid-cycling accelerator

Abstract: A resonant power supply has been proposed as an efficient power supply for a future 60-GeV, Kaon-producing accelerator. The engineering design of the electric system of the main-ring power supplies is described. It is shown that the resonant power supply can be built with standard commercially available components. The most critical component is the bypass switch, which requires gate-turn off thyristors, connected in parallel. Standard metal-clad switchgear can be used for the AC system. The resonant power supplies can be fed directly from the 115-kV utility network, but the resonance power supplies draw pulse loads from the utility network. This pulse may produce disturbances. AC filter and reactive power compensation is needed for economical operation. >

Earth-To-Satellite Microwave Beams: Innovative Approach To Space Power

Abstract: A new space power concept incorporating earth-to-satellite microwave power beams coupled to onboard regenerative electrochemical energy storage is proposed for energizing defensive satellite constellations. The system addresses housekeeping, orbital maneuvering and burst mode power requirements, and offers an attractive alternative to the nuclear and solar space power systems currently envisioned for this application. This energy-conversion system incorporates six steps: (1) generate primary DC power at surface stations along the satellite ground-track, (2) convert to microwave (RF) frequencies, (3) transmit in a narrow beam to spacecraft using phased-array antennas which track and lock-on to satellite receivers as they pass in range during a fraction of their orbit, (4) receive the energy and convert to DC in space using lightweight and inexpensive rectennas; (5) store the energy onboard as chemical energy by electrolysis of water to oxygen and hydrogen and (6) recover free energy onboard the spacecraft during the balance of the orbit continuously or on demand as pulsed power with a high power-density fuel cell. Component and overall systems considerations of this scheme are discussed in comparison with alternatives, outstanding research problems are defined and preliminary analyses are described. These include orbital mechanics and ground tracks of satellites, accessibility of orbiters to microwave beams, transmission efficiencies, electronic and mechanical designs of the transmitter and rectenna, regenerative fuel cell energy storage, power conditioning and thermal management. The development of readily space-deployable rectennae, their supporting structures, and high specific power solid oxide monolithic fuels cells are the main pacing technologies leading to a wholly non-nuclear space power system capable of supporting all defensive satellite power requirements.© (1988) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Power supply network of printed circuit board

Abstract: In a power supply network network of a printed circuit board, a through hole network for power supply electrically connected to main power supply pads connected with power supply cables is electrically and substantially independent of an internal network comprising networks of power supply layers on the like and a through hold network for load. Thereby, each of source currents supplied from the power supply cables reaches the through hole network for each load, once, via the through hold network for power supply and horizontal buses, therefore the dispersion in the drop of voltage across the main power supply pads and each of the loads is effectively decreased.

Refractory metal alloys and composites for space power systems

Abstract: Space power requirements for future NASA and other U.S. missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary source to meet these high levels of electrical demand. One way to achieve maximum efficiency is to operate the power supply, energy conversion system, and related components at relatively high temperatures. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide baseline information for space power systems in the 1900's and the 21st century. Basic research on the tensile and creep properties of fibers, matrices, and composites is discussed.

Power Electronics - an Emerging Technology

Abstract: The author presents a tutorial review of power electronics and drives in which the status of the technology and its future are discussed. He focuses on power semiconductor devices, converter circuits, AC machine control, and microcomputer applications in power electronics systems. He examines the impact of computer-aided design and artificial intelligence, and he summarizes the technological trends. He predicts that the technology will grow with increasing momentum as component technologies continue to grow. >

A compact board-mounted power supply module for telecommunications systems

Abstract: The authors describe the circuit and components of a compact board-mounted power supply module. A single-ended forward converter without a reset circuit reduces transformer size and circuit power dissipation. A simple, wideband optoisolation circuit extends the feedback loop bandwidth and reduces the size of the output smoothing filter. A low-profile surface-mounted transformer allows the power supply module to be mounted on a 15 mm-pitch circuit board. The 10 W power supply module can be reduced to 20 cm/sup 3/, which is half the conventional size. >