Showing papers on "Electric power published in 1994"

Pulsewidth modulation for electronic power conversion

Abstract: The efficient and fast control of electric power forms part of the key technologies of modern automated production It is performed using electronic power converters The converters transfer energy from a source to a controlled process in a quantized fashion, using semiconductor switches which are turned on and off at fast repetition rates The algorithms which generate the switching functions-pulsewidth-modulation techniques-are manifold They range from simple averaging schemes to involved methods of real-time optimization This paper gives an overview >

Electric power accumulating apparatus and electric power system

Abstract: An electric power accumulating apparatus utilizing a prallel and/or serial array of plural secondary batteries comprises means for detecting abnormality in each of the secondary batteries, means for electrically detaching the output terminals of the secondary battery showing abnormality and, in case of serial connection, shortcircuiting the terminals to which the secondary battery showing abnormality has been connected, and means for compensating the voltage corresponding to the detached battery, thereby providing improved safety, stable output and extended service lives of the secondary batteries.

Raodway-powered electric vehicle system having onboard power metering and communication channel features

Abstract: A roadway-powered electric vehicle (RPEV) system includes: (1) an all-electric vehicle; and (2) a roadway network over which the vehicle travels. The all-electric vehicle has one or more onboard energy storage elements or devices that can be rapidly charged or energized with energy obtained from an electrical current, such as a network of electromechanical batteries. The electric vehicle further includes an on-board controller that extracts energy from the energy storage elements, as needed, and converts such extracted energy to electrical power used to propel the electric vehicle. The energy storage elements may be charged while the vehicle is in operation. The charging occurs through a network of power coupling elements, e.g., coils, embedded in the roadway. The RPEV system also includes: (1) an onboard power meter; (2) a wide bandwidth communication channel to allow information signals to be sent to, and received from, the RPEV while it is in use; (3) automated garaging that couples power to the RPEV for both replenishing the onboard energy source and to bring the interior climate of the vehicle to a comfortable level before the driver and/or passengers get in; (4) electronic coupling between "master" and "slave" RPEV's in order to increase passenger capacity; (5) inductive heating coils at passenger loading/unloading zones in order to increase passenger safety; and (6) an ergonomically designed passenger compartment.

Electric railway traction. Part 3. Traction power supplies

Abstract: Power is transmitted to electric railway locomotives and vehicles using DC or single-phase AC networks. The parallel development of traction technology in industrialised countries has led to a plethora of different electrification systems. This article covers the electrical engineering aspects of DC and single-phase AC traction power transmission systems.

Facility for refueling of clean air vehicles/marine craft and power generation

Abstract: A facility for the generation of electrical power and products for the refueling of clean air vehicles (CAV's) and marine craft and for use by the facility and/or general market. A host of electrical power generation devices including solar panels, solar collectors, wave action generators, reverse osmosis water purification apparatus, electrolizers, hydrogen/oxygen purifiers and compressors, storage units, fuel cells, AC/DC motors and generators and the various connectors, gauges and networks used for interconnecting and dispensing the products of a combined source system are used jointly and severally in a unique siting about an elevated roadway or railway. The idealized site for this combined system is a bridge, or other elevated structures such as lock superstructures, dam faces and otherwise towering facilities. The siting structure is most desirably located adjacent a water source, be it a river, bay, tidal estuary or the like. In addition to the generation of DC electrical power, gaseous products such as may be marketed for their intrinsic value or used in the production of additional power via fuel cell operation are also marketed or used/consumed on site. Unique improvements are made in wind generators, a tidal barge generation system and a wave air generator.

Wind farm generation scheme utilizing electrolysis to create gaseous fuel for a constant output generator

Abstract: Novel means for smoothing electrical power output from wind powered electrical generators is provided. The means utilizes at least some of the power output to convert water into hydrogen, store and burn the hydrogen to produce energy, and use the energy from the burning for the generation of electricity. The means includes a plurality of electrolysis modules consisting of electrolytic cells connected in series, with at least two modules connected in parallel by a switch means.

Starter/generator system having multivoltage generation capability

Abstract: An electric power starter/generator, for converting electrical energy from a remote dc electrical power source to mechanical energy to start a turbine engine in the start mode, and for converting mechanical energy from the turbine engine to electrical energy to power utilization equipment in the generate mode, comprises a shaft for transferring rotational mechanical energy between the electric power starter/generator and the turbine engine, a permanent magnet synchronous machine having a rotor driveably coupled to the shaft and a stator. The permanent magnet synchronous machine produces polyphase ac electric power when driven as a generator, and rotational mechanical energy when driven as a motor. A bidirectional ac-dc power converter having a dc and an ac input/output produces variable frequency polyphase ac excitation from the dc electrical energy at the dc input/output to drive the permanent magnet synchronous machine as a brushless dc motor to generate rotational mechanical energy to start the turbine engine during the start mode. The power converter alternately produces dc electrical energy from the polyphase ac electrical energy generated by the permanent magnet synchronous machine when driven by the turbine engine during the generate mode.

Vehicle transmission system with variable speed drive

Abstract: A vehicle transmission system is described which employs a split power path design to achieve continuously variable speed ratios. A motor-generator unit is provided for converting a fraction of the input power into electrical power, and a second motor-generator and differential gear mechanism are employed to re-combine the two power components before transmitting the mechanical power through a gearbox. Electrical power dissipation means allows the transmission system to provide slippage when accelerating a load from rest, and it also assists in shifting and in braking. An electronic motor controller coordinates feedback signals from various sensors and controls the dynamic performance of the entire system. The motor-generators are integrated with the housing of the transmission and have water jackets to assist in heat dissipation. The motor-generator pair and the power dissipation elements are all cooled by a circulating fluid which transfers heat from these components to an external heat exchanger.

Heat responsive power interrupting device

Abstract: An electric device is provided as an interface between a permanent power source (e.g., an electric wall outlet) and an electrical appliance for interrupting electrical power to the appliance in the event the temperature of either the power cord plug of the electrical appliance or permanent power source rises above a predetermined temperature. The electric device detachably couples to the electric power terminals of both the permanent power source and electrical appliance and is sensitive to the temperature of the aforementioned terminals. The electric device includes first and second temperature switching elements which are responsive to interrupt electrical power from the permanent power source to the appliance when either of the terminals is of a temperature which equates with a first predetermined temperature determined by the first temperature switching element or a second predetermined temperature determined by the second temperature switching element.

System and method for economic dispatching of electrical power

Abstract: The present invention relates to methods and systems for economically dispatching electrical power. The present invention utilizes real-time heat rates for a plurality of power generating units, e.g., steam turbines, and corresponding emission data for each unit, to dispatch electrical power at the lowest possible cost. The method of the present invention also compares the cost associated with generating power to the cost to purchase power from other electric utilities to achieve maximum cost savings associated with the dispatching of the electrical power.

Vehicle with electric motor

Abstract: An electrically powered vehicle wherein the electric power may be provided by an auxiliary electric motor with power assist being determined by a manual force applied by an operator for manually propelling the vehicle. The vehicle control includes a method for determining when the vehicle is being started from a stop and for providing a gradual application of electric power assist during such start-up. In addition, if the operator calls for an abrupt change in power assist, the actual power assist is applied only gradually to provide smoother operation. The system also has self-checking functions and the electric power assist is disabled in response to certain types of failures. However, the operator is warned in advance that the power will be shut down so as to avoid emergency situations. The self-checking provides an arrangement for checking when the speed sensor is inoperative by sensing certain output characteristics of the speed sensor and the force application. In addition, the device precludes the application of electric power assist under conditions when the battery might be depleted and when the vehicle is not actually moving. Various arrangements are provided for also checking the output of the battery and precluding power assist or controlling the power assist, depending upon the state of the battery. In addition, the vehicle may include other electrical accessories, and these are powered by an auxiliary battery. The auxiliary battery, however, may be charged from the main battery.

Harmonic measurements, analysis, and power factor correction in a modern steel manufacturing facility

Abstract: Maximizing electric power transfer directly affects the productivity of an electric arc furnace operation. Arc furnaces and rolling mill loads operate at power factors that result in penalty charges and lower bus voltages. In addition, the nonlinear characteristics of the furnace arcs and rolling mill drives generate significant harmonic currents that flow through the plant and utility power system. These harmonic currents cause system voltage distortion and power loss in the system, and can interact with power factor correction capacitor banks leading to equipment failures. This paper presents the analytical technique used to correct power factor in a modern steel manufacturing facility. The study included field measurements, harmonic analysis, and filter design work to reduce the amount of harmonic distortion in the plant. The modeling of arc furnaces and rolling mills for a harmonic analysis study is also discussed. The solutions recommended in this paper to increase power factor and reduce harmonics can be applied to other steel manufacturing facilities to improve power quality and therefore plant productivity.

Method and apparatus for managing power consumption of external devices for personal computers using a power management coordinator

Abstract: A system for managing power consumption in a personal computer. To date most techniques for managing power consumption in personal computers have been for the purpose of extending battery life of portable computers whose usual source of power is a battery. By providing techniques for managing power consumption in desktop computers as well, whose usual source of power is a 120 volt, 60 Hz. wall connection, substantial savings in electric power consumption are possible due to the large number of computers which are left on for extended periods of time, even when not being actively used. The present invention providing a software and hardware architecture and mechanisms for managing the power consumption of peripheral devices through their device drivers, a global event messaging scheme and power management coordination software.

Hydraulic machines : turbines and pumps

Abstract: This second edition of "Hydraulic Machines" is devoted to the operating principles, design and performance characteristics of hydraulic machines used in electric power plants, municiple facilities, construction works, hydraulic engineering industry and agriculture. The book emphasizes the types and construction of the machinery, especially the mechanical aspects of their operation, including head, discharge, power, efficiency, cavitation factors, reliability and maintenance.

Power systems for plug-in modules

Abstract: A system for supplying primary electrical power to modular components of electronic equipment. The system uses a battery power source mounted either in the module or as part of a battery pack that attaches to the module. Module circuitry supplies a recharge current to the battery power source. A charge circuit charges the batteries in a parallel and supplies power to the module connecting the batteries in series. Circuitry also determines the amount of battery power source used for an operation of the module and sends a recharge current to the battery power source corresponding to the power consumed by the module and based on the available recharge current.

Energy efficiency, market failures, and government policy

Abstract: This paper presents a framework for evaluating engineering-economic evidence on the diffusion of energy efficiency improvements. Four examples are evaluated within this framework. The analysis provides evidence of market failures related to energy efficiency. Specific market failures that may impede the adoption of cost-effective energy efficiency are discussed. Two programs that have had a major impact in overcoming these market failures, utility DSM programs and appliance standards, are described.

Apparatus for operating a fluorescent lamp of an image forming apparatus

Abstract: An apparatus for operating a fluorescent lamp having first and second power source circuits, the second power source circuit including a high frequency transformer having two or more outputs for supplying pre-heating electric currents to filaments, the second power source circuit being arranged to be controllable individually from the first power source circuit for supplying a tube electric current to turn on a fluorescent lamp so that the electric power level for pre-heating the filaments is switched between a state where a light adjustment is performed by turning on/off a tube electric current at high frequency and a state where the fluorescent lamp is turned off in a standby mode.

Automatic electric power generator control

Abstract: A controller operates to start an electric power generator, for example a gasoline engine electric power generator, when a demand is made for electric power when the user turns on an electric powered device, such as a circular saw, that is to be used. The generator runs as long as there is a demand for power, and when the demand ends, the generator stops after a predetermined adjustable delay period. Additionally, in the event the engine is to be started under cold start-up conditions, the starter is operated to avoid cyclical starting/stalling of the generator engine. When a demand is made on the generator for power, the controller senses a circuit closure, turns on the starter of the generator, and, after the generator cranks, the power is applied to the saw and it starts to operate. The starter is controllably disabled after the generator is operational. The engine driving the generator will stop after a predetermined delay after the power demand is removed. If the user switches off the saw for a short time and then turns it on again before the delay times out, then the timing sequence (to shut the generator off temporarily) is aborted. If, however, the user stops sawing longer than the timeout period, the generator is stopped, and it will automatically start again when the user is ready to saw again.

Remote power cost display system

Abstract: A remote electrical power meter display system for indicating to a consumer the actual costs associated with electrical power use includes two units: a wattmeter/transmitter for detecting instantaneous power consumption, and a remote reading unit for displaying the cost of electrical power at the instantaneous rate of power consumption. The wattmeter/transmitter includes an inductive coil pickup operatively connected to each hot lead of the utility service of a premises installation, and a voltage pickup is coupled to each hot lead and ground to detect the voltage delivered to the customer installation. A sample and hold circuit converts the voltage and current values to digital signals and feeds them to a calculator device which generates an instantaneous power use signal. This signal is fed to a carrier current transmitter which generates a coded carrier current signal indicative of the power consumption that is fed into the wiring of the customer installation to be transmitted throughout the customer's premises. The remote reading unit is plugged into any power outlet in the premises to provide a display of the cost of power consumption of the entire customer installation at any instant. The remote reading unit includes a carrier current receiver that decodes the signal from the wattmeter and a clock/calendar module and a power cost look-up table that stores power rate data as a function of time of day and date. The power rate data and power consumption data are fed to a calculator device, which generates a signal indicative of the cost of power used at the instant of sampling and transmits the signal to a display device. The sample and hold circuit is operated reiteratively and frequently, to inform the consumer on a continuing basis of the cost of power consumed at the customer's premises.

Transmission arrangement for electric power assisted bicycle

Abstract: An improved electric power assisted bicycle including a electric motor and planetary transmission arrangement constructed to permit ease of assembly and maintain a low cost and an improved one-way clutch that eliminates the need for bearings for rotatably aligning the elements of the clutch.

Electric power assisted bicycle

Abstract: The present invention relates to an electrically power assisted bicycle wherein the electrical power assist components are comprised of an electric motor (43) and transmission as one unit and a battery (46) as another unit. The electrical motor (43) and the electrical battery (46) are disposed substantially weight-balanced with respect to the crank axis of a manually operated crankshaft. In this way, a low center of gravity and improved manoeuvrability of the bicycle is obtained.

Wireless type power supply apparatus for submerged electric machine

Abstract: PURPOSE:To supply an electric power to a submerged electric machine. CONSTITUTION:A receiving antenna 1 connected to an electric machine such as a submerged pump 3 is provided in the water 8. A transmitting antenna 4 is connected to a transmitter 6 which generates a radio frequency power of a MHz band. The transmitting antenna is provided in the air or in the water and an electric energy is transmitted to the receiving antenna to drive the submerged pump.

Control of electric loads during generator failure in a multi-generator system

Abstract: In response to the loss of a generator in an electrical power system, all operating electrical loads are automatically switched to a second generator, and the electric power system continues to provide power to all of the loads. The total power required to operate all operating loads is permitted to exceed the nominal rated capacity of the operating generator, and the winding temperature or other critical hotspot temperature of the operating generator is monitored to determine whether thermal stress limits will be exceeded. If the critical hotspot temperature approaches the thermal stress limit, certain electrical loads are disconnected via a pre-programmed load shed priority schedule, and thereafter loads are re-connected as other loads are de-energized or if the critical hotspot temperature decreases.

Power supply apparatus for electric vehicle

Abstract: A power supply apparatus for an electric vehicle, which is adapted to restrain battery discharge due to current pulsations of a load. The apparatus has a battery, a coil and a capacitor connected to the battery via the coil to supply power. The apparatus controls the burden ratio of discharge current between the battery and the capacitor in accordance with various operation modes of the electric vehicle to extend a travelable distance thereof.

On techniques for localization of sources producing distortion in electric power networks. Discussion. Authors' reply

Abstract: This paper attempts to explore the underlying network theory relevant to the analysis of harmonic power direction. Balanced three-phase networks reduced to single-phase equivalents are considered. It is shown that the location of an harmonic source may be determined from the harmonic frequency active power direction

Secondary battery power storage system

Abstract: The present invention provides a distributed secondary battery type power storage system capable of maintaining the soundness of the secondary battery and of efficient electric power charging and discharging operations. The secondary battery power storage system comprises a secondary battery connected to a load, a charge/discharge unit connectable to a power system and connected to the secondary battery, and a plurality of loads connected to the charge/discharge unit. A power receiving object is selected and a capacity is determined on the basis of information about the operating condition of the plurality of loads, and the surplus electric power remaining in the secondary battery after feeding electric power from the secondary battery to the load is fed to the selected power receiving object through the charge/discharge unit. The secondary battery power storage system is capable of maintaining the soundness of the secondary battery and of efficient charging and discharging operation.

Non-railbound vehicle with an electric motor

Abstract: The invention relates to a non-railbound vehicle with an electric motor. To modify such vehicles in such a way that the specific fuel consumption remains as low as possible and the maximum possible power of the internal combustion engine is fully available to the vehicle drive in case of need without the sacrifice of any convenience relating to the electrical operation of subsidiary functions, it is proposed that the control system (FST) provide the on-board low-voltage system with part of the power produced by the generator and that, during operational phases in which the full power of the engine (1) is required for propulsion, a program in the electronic control system (FST) provide for the temporary interruption (interrupter 11) of the electric power supply from the generator (2) to the low-voltage system, the subsidiary electric consumers (10) then being powered from the vehicle battery (10).