Showing papers on "Power module published in 1980"

Solar power system requiring no active control device

Abstract: A solar power system has a photovoltaic array having a locus of peak power points for various insolation levels, a voltage-dependent variable resistance load such as a water electrolysis unit electrically connected to the array, and a demand-dependent variable resistance load such as a DC to AC inverter connected in parallel with the electrolysis unit. The electrolysis unit or other voltage-dependent variable resistance load has a voltage-current characteristic in which the operating point is displaced from the array's peak power point for most insolation levels. The characteristic is displaced towards higher voltage-lower current operating points. The inverter may move the operating point of the photovoltaic array toward its peak power point when the load requires power. The system may be designed so that the array operates within about 5 percent of its peak power point over a wide range of inverter power demands. A fuel cell may be connected in parallel with the array to provide power to the inverter at low insolation levels, at night or in low sunlight. The fuel cell may use the hydrogen produced by the electrolysis unit for fuel. The total photovoltaic power made available by the system of this invention is generally greater than 95 percent and often greater than 98 percent of the maximum power which the photovoltaic array may produce for many insolation levels.

Alternating polarity power supply control apparatus

Abstract: An electronic switching circuit is provided for controlling transfer of electrical power from an alternating polarity electrical power supply to a load means through use of a field-effect transistor device as the primary power controlling element.

Solar power supply for spacecraft

Abstract: A solar power supply for a spacecraft comprises an array of semiconductor devices for photovoltaic conversion of sunlight into electrical energy. Each semiconductor device is secured by a substantially stress-free electrically conductive joint to a flexible dielectric substrate that can be folded into a compact stowage configuration or opened into an elongate operational configuration. The stress-free joint is formed by securing an electrical terminal of the semiconductor device to a stress-relieving electrical conductor that is affixed to the substrate. Preferably, the stress-relieving conductor is a metallic wire mesh, a peripheral portion of which is adhesively bonded to the substrate circumjacent an aperture in the substrate. A pattern of metallic traces formed on the substrate provides a circuit for connecting the wire mesh to connectors for coupling electrical power generated by the array of semiconductor devices to an electrical load on the spacecraft.

Method and apparatus for controlling a resonant power module

Abstract: A method and apparatus for controlling a resonant power module comprising a resonant power circuit which is coupled to a load. First and second switching elements are coupled to the resonant circuit for alternately supplying a flow of current. Trigger generator means are provided for supplying trigger signals to alternately enable the first and second switching elements. A control means is coupled to the trigger generator for operating the power module in a first mode in which the resonant circuit current is controlled by varying the repetition rate of the trigger signals. The control means operates the power module in a second mode by maintaining the trigger signal repetition rate at a fixed limit and controlling the resonant circuit current by varying the on/off duty cycle of the power module.

A Two-Quadrant Transistor Chopper for an Electric Vehicle Drive

Abstract: A two-quadrant dc-dc transistor converter capable of delivering 400 A motoring current and of generating 200 A braking current is described. The chopper operates from a 108-V dc source (54 lead-acid cells) and supplies the armature current of a separately excited dc machine in an electric vehicle application (3000-lb commuter-type vehicle). The chopper employs high-current transistors specifically developed for the application and power diodes packaged together in power module form. Snubber networks which reduce both turn-on and turn-off device stresses are employed. The interaction of the snubber networks for the motoring and braking transistors is described and design considerations presented. It was found that for these snubbers a minimum on-time and a minimum off-time for the transistors must be maintained to ensure that the transistors' dynamic load lines never enter into the region of forward bias or reversed bias second breakdown. A technique is described which instantaneously detects a transistor failure and initiates the appropriate action in order to prevent machine overcurrent and overtorque. Factors are discussed which are crucial to ensure proper transitions from motoring to braking and to inhibit device power dissipation due to parasitic currents. The selection of a variable-frequency/variable-pulsewidth switching strategy and protection and control techniques unique to high-current transistor choppers are discussed.

Marine wave powered generator - has floating column with oscillating lobed float and ballast weight to maintain specified angle

Abstract: The power generator floats on the sea in a predetermined position. It consists of an articulated dorsal tube formed from a number of waterproof and flexible annular segments having crenelated joints. Conduits contain flexible cables which hold the sections together. A ballast weight holds the structure at a certain angle, and the power module is in the form of a split section sleeve fitted around the column. A float or "duck" having a frontal lobe, oscillates with wave action, imparting a rotating motion to the power generating module. The complete assembly consists of several similar units connected together.

High Voltage DC Cable for Bulk Power Transmission

Abstract: After summarizing the technical and economical reasons which can make dc attractive for HV bulk power transmission, the main existing cable plants are shortly described and a tentative outlook of the basic requirements for future cable connections is given. Then significant examples are shown of the power per cable circuit Which can be transmitted with natural and with forced cooling. The report is completed with a brief summary of some research activity under way in this field.

Optical Power Supply for Measuring or Communication Devices at High-Voltage Levels

Abstract: Measuring or communication devices at high-voltage levels having small power consumption can be supplied by generating optical power with light emitting diodes at ground potential, transmitting the power through a glass rod and detecting it with solar cells at high potential.

A two-quadrant transistor chopper for an electric vehicle drive

Abstract: A two-quadrant dc-dc transistor converter capable of delivering 400 A motoring current and of generating 200 A braking current is described. The chopper operates from a 108-V dc source (54 lead-acid cells) and supplies the armature current of a separately excited dc machine in an electric vehicle application (3000-lb commuter-type vehicle). The chopper employs high-current transistors specifically developed for the application and power diodes packaged together in power module form. Snubber networks which reduce both turn-on and turn-off device stresses are employed. The interaction of the snubber networks for the motoring and braking transistors is described and design considerations presented. It was found that for these snubbers a minimum on-time and a minimum off-time for the transistors must be maintained to ensure that the transistors' dynamic load lines never enter into the region of forward bias or reversed bias second breakdown. A technique is described which instantaneously detects a transistor failure and initiates the appropriate action in order to prevent machine overcurrent and overtorque. Factors are discussed which are crucial to ensure proper transitions from motoring to braking and to inhibit device power dissipation due to parasitic currents. The selection of a variable-frequency/variable-pulsewidth switching strategy and protection and control techniques unique to high-current transistor choppers are discussed.

A dish-Stirling solar-thermal power system

Abstract: This paper presents results of a preliminary design/economic study of a first-generation point focusing distributed receiver solar-thermal electric system optimized for application to industrial and small community power plants at power levels up to 10 MWe. Power conversion is provided by small Stirling cycle engines mounted at the focus of paraboloidal solar concentrators. The output of multiple power modules (concentrator, receiver, engine, and electric generator) is collected by means of a conventional electrical system and interfaced with a utility grid. Based on the United Stirling P-75 engine, a 1 MWe system employing mass-produced components (100,000 modules/year) could produce electricity at costs competitive with those projected for electricity generated by more conventional means, e.g. with fossil fuels.

Future and Limits of Power I.C.

Abstract: In this paper we present a review of the actual realizations and future trends for the power IC technologies Two different processes for high voltage and high current are discussed and compared Particular attention is devoted to surface stability phenomena and their implications on reliability The actual panorama for medium and high power packages is discussed Starting from the phisical limit of the maximum power that can "be dissipated in practical application conditions, we analyse the maximum power available at the out put for three classes of operations: DC, AC audio, and class D switching amplifiers For the first two applications the actual limits appear to be set mainly by the extermal context (power supply regulation, thermal heatsink capability) instead of electrical performance of the silicon chip itself So the actual implementations that provide 30 W continuous power and a voltage-current product in excess of 200 W, appear as a maximum Class D limits appear to be mainly connected to the intrinsic characteristics of power devices, like sustaining-saturation voltage ratio, commutation speed and 2nd breakdown ruggedness Actual implementations in 44 V technology reach 80 W for bipolar loads, so 150 W are possible when considering unipolar loads But the new developments in power technologies indicate the way how to increase them

Electrical Power System Design Features of a Modern Large Polyethylene Plant

Abstract: A modern large polyethylene plant requires a sophisticated electrical power supply to meet the requirements of a continuous process industry. The principal features of such an electrical power system are summarized. The power system was designed to achieve project objectives which stressed safety of operation, ease of maintenance, and high reliability. Some of the modern design features discussed are dual 230-kV power supply lines; low-profile 230-kV bus work; personnel safety grounding of main substation to reduce step and touch potential to safe levels; transfer trip signals to utilize the utility company's switching equipment; extensive protective devices to detect and initiate switching equipment action for power equipment malfunctions or power system faults; vacuum switched under-load tap changers on main power transformers; vacuum breakers for 13.8-kV switching equipment; climate-controlled elevated substation buildings to permit bottom entrance and exit with all power and control cables; nonmetallic sheathed power and control cables in open cable tray; medium resistance ground derived by zig-zag grounding transformers in the 13.8-kV distribution system; high-resistance grounding at the secondary wye connection of all 4.

Advanced development of a programmable power processor

Abstract: The need for the development of a multipurpose flexible programmable power processor (PPP) has increased significantly in recent years to reduce ever rising development costs One of the program requirements the PPP specification will cover is the 25 kW power module power conversion needs The 25 kW power module could support the Space Shuttle program during the 1980s and 1990s and could be the stepping stone to future large space programs Trades that led to selection of a microprocessor controlled power processor are briefly discussed Emphasis is given to the power processing equipment that uses a microprocessor to provide versatility that allows multiple use and to provide for future growth by reprogramming output voltage to a higher level (to 120 V from 30 V) Component selection and design considerations are also discussed

An interferometer-based phase control system

Abstract: A system for focusing and pointing the SPS power beam is discussed. The system is ground based and closed loop. One receiving antenna is required on earth. A conventional uplinked data channel transmits an 8-bit phase error correction back to the SPS for sequential calibration of each power module. Beam pointing resolution is better than 140 meters at the rectenna.

Manufacture of power module

Abstract: PURPOSE:To prevent the crack of a substrate by soldering a power element of semiconductor to a metal-plated Al radiating plate and by sticking the substrate for the control circuit to said plate with elastic Si group adhesive. CONSTITUTION:The power element 3 is soldered to the Cu or Sn-plated Al radiating plate 1, the alumina substrate 5 is stuck to the plate with the Si system adhesive 4. Since the coefficient of thermal expansion of Al is greater than that of Cu, the alumina substrate is cracked when the solder or epoxy resin adhesive is used for attaching the element to the alumina substrate of a relatively great area. When Si group adhesive is used, a crack of the substrate caused by heat shock can be prevented by the elasticity and the radiation from the control circuit can also be improved.

The simulation of aircraft electrical power systems

Abstract: This paper describes the digital modelling and simu lation of aircraft electrical power systems. Models of the main power generators, automatic voltage regulators, and a polyphase transformer-rectifier unit typical of ac-to-dc power conversion equipment are described. The main generator is the most com plex component in the system to model, and its per formance with a radar load and two generators in parallel is described. These two examples indicate how individual models may be made to interact and how the tensor approach may be used to eventually form a complete system.

Design and breadboard evaluation of the SPS reference phase control system concept

Abstract: Efficient operation of a very large phased array such as the proposed solar power satellite, requires precision focusing and pointing of the power beam; ie, the power beam must have a planar wavefront directed precisely at the center of the target antenna (rectenna) To maintain such a power beam requires real-time phase compensation at each subaperture in order to adjust for structural deformations and other transitory factors In the current solar power satellite (SPS) baseline, the spaceborne antenna (Spacetenna) is an active retrodirective array A pilot signal transmitted from the center of the rectenna is phase-conjugated at each subaperture (power module) of the spacetenna, thereby assuring that the radiated composite wave is focused on the target This scheme requires a large amount of precision electronic circuitry on the spacetenna Specifically, pilot receivers must be located at each power module and an adaptive distribution network is required in order to provide a properly phased reference signal at each conjugator