Showing papers on "Electric power published in 1989"

Power semiconductor device figure of merit for high-frequency applications

Abstract: A figure of merit (the Baliga high-frequency figure of merit) is derived for power semiconductor devices operating in high-frequency circuits. Using this figure of merit, it is predicted that the power losses incurred in the power device will increase as the square root of the operating frequency and approximately in proportion to the output power. By relating the device power dissipation to the intrinsic material parameters, it is shown that the power loss can be reduced by using semiconductors with larger mobility and critical electric field for breakdown. Examination of data in the literature indicates that significant performance improvement can be achieved by replacing silicon with gallium arsenide, silicon carbide, or semiconducting diamond. >

Subscriber electric power load control system

Abstract: Electric power uses or loads in a premises are controlled or managed depending upon whether the use is for heating, hot water, heat pump, air conditioning, lights, appliances, pumps, etc., according to programs that are controlled by the electric Power Company, for the purposes of spreading power uses at the premises over a day or other time interval, to avoid peak load periods encountered by the Power Company, while still providing the normal comfort levels required by the subscriber from the various power uses. Power levels of several uses at the subscriber's premises are sensed and the power for each use is controlled according to a program that includes a schedule of power level and/or the time of day that is inserted in the program or controlled in the program by the Power Company to accomplish the spreading. In a particular embodiment, a programmed computer unit is provided at the premises that is monitored by the Power Company via the subscribers telephone line. Changes in the computer program are inserted in the unit by the Power Company, via the telephone line; and signals within and throughout the premises for detecting and controlling power uses are transmitted to and from the unit over the premises power line.

Automatic mixing faucet

Abstract: An automatic service water tap is disclosed in which a battery operated motor is provided for controlling a water supply valve in response to the presence or absence of an object positioned within the range of an infrared generating and detecting system mounted in the tap. The valve operates using only a small amount of electric power under the control of a circuit which draws no electric power once the valve is moved to its opened or closed condition. Thus the consumption of the electric power is minimized to almost zero and the valve can be utilized for a long period of time only with a small single battery.

Doubly fed generator variable speed generation control system

Abstract: Disclosed is a device and method to control the conversion of an arbitrary resource energy into mechanical energy and subsequently into electric energy with a variable-speed generation system utilizing a turbine and a doubly-fed generator, to be connected directly to a power grid of a certain grid frequency. Via electronic control of the rotor speed by controlling the rotor winding excitation frequency, the device has the capability of providing an optimum tradeoff in maximum turbine efficiency and minimal generator losses to secure maximum efficiency of the total conversion process, irrespective of varying resource and electric load conditions. The excitation requirements of the generator are confined to moderate levels and yet a wide rotor-speed variation margin, starting from zero speed, is permitted. An integrated strategy is implemented which effectively coordinates the execution of these tasks and the independent control of the generator terminal voltage as well as the active and reactive electric power output. All signal processing as required correspondingly is carried out without the need for cumbersome measurements of turbine input and output power or generator losses.

Real time pricing to assist in load frequency control

Abstract: We study the use of real time prices to assist in the control of frequency and tie line deviations in electric power systems The role of such prices, if any, would yield the practical limit to the trend in electric power systems of varying prices on ever faster time scales The application of prices in electric power systems to increase the efficient use of resources is an established technique The pricing schemes can be classified by time scales Energy adjustment charges vary seasonally or monthly, while time of day rates vary two or three times per day The power brokering system of 18 Florida Utilities operates on an hourly time scale In a spot price market of buyers and sellers of electric power, prices adapt to system operation conditions such as changes in system lambda, the effect of generation shortages, and the effect of line overloads The fastest spot price that has been implemented to date is 30 minutes (most implementations involve 1 hour time steps, which may be prespecified 24 hours in advance) On a five minute time scale is system lambda, a shadow price, used internally by electric utilities for economic dispatch A key assumption of spot pricing and economic dispatch is that the power system is in quasi-steady state; ie power system dynamics involving frequency, voltage, etc are ignored, and only Kirchoff's laws for network are considered The paper explores pricing at time scales where the quasi-steady state assumption is no longer valid

Drive system for turbochargers with rotary electric machines

Abstract: A turbocharger drive system associated with an internal combustion engine includes a plurality of turbo­chargers drivable by exhaust gases from the engine, a plu­rality of rotary electric machines mounted on the rotatable shafts, respectively, of the turbochargers and operable as electric motors or generators, and a single rotary electric machine coupled to the rotatable shaft of the engine. When the engine rotates at a low speed and under a high load, the rotary electric machine coupled to the engine shaft oper­ates as an electric generator to generate electric power to drive the rotary electric machines mounted on the turb­ocharger shafts as electric motors, so that the boost pres­sure is increased to increase the output power of the engine. Since the multistage turbochargers are power-­assisted by the respective rotary electric machines, the boost pressure builds up sharply. When the engine rotates at a high speed, the rotary electric machines combined with the turbochargers generate electric power to drive the rotary electric machine coupled to the engine shaft as an electric motor, thus feeding exhaust energy back to the engine output power.

Power line communication system

Abstract: A power line communication system which includes an electrical power line having one or more loads which feed objectionable electrical noise back into the power line. The electrical noise is attenuated across a broad frequency range to enable effective communication over the power line by a directional common mode trap located between the point where the communication signals are applied to the power line and the source of the electrical noise. The trap requires only a capacitor for each electrical phase and a 1:1 transformer having a magnetic core and single turn, straight through windings. The trap is connected to provide a low impedance path to ground for the electrical noise, while providing a high impedance to ground for the communication signals.

Brushless doubly-fed generator control system

Abstract: An energy conversion generation system receives energy from a resource and converts the energy into electrical power for supply to a polyphase electric power grid operating at a system frequency A prime mover driven by the resource energy and a converter, such as a power electronic converter, for produces excitation power from power received from a converter power source A brushless doubly-fed generator has a rotor with rotor windings and a stator with stator windings comprising first and second polyphase stator systems The rotor is driven by the prime mover The first stator system supplies the electrical power to the grid, and the second stator system receives the excitation power from the converter A sensor senses a parameter of the electrical power output supplied to the grid and produces a sensor signal corresponding to the sensed parameter A controller controls the converter in response to the sensor signal The controller establi This invention was made with government support under Grant No 79-85BP24332, awarded by the Bonneville Power Administration The United States government has certain rights in this invention

Brushless generator having AC excitation in generating and starting modes

Abstract: An excitation system for a brushless generator having a main generator portion including a field winding disposed on a rotor and an armature winding disposed in a stator includes an exciter portion having a set of polyphase exciter field windings disposed in the stator and an armature winding disposed on the rotor and coupled to the main generator portion field winding. A first power converter is coupled to the main generator armature winding and a second power converter is coupled to the set of polyphase exciter field windings. Contactors are operable in a starting mode of operation to couple a source of electrical power to the first and second power converters and are operable in a generating mode to disconnect the source of electrical power from the first and second power converters. A control unit controls the power converters such that the power converters provide AC power to the main generator armature winding and to the set of polyphase exciter field windings during operation of the starting mode so that the rotor is accelerated. The control unit operates the power converters in the generating mode such that the second power converter provides AC power to the set of polyphase exciter field windings and the first power converter develops constant-frequency AC power.

Connectorless power supply for an aircraft-passenger entertainment system

Abstract: The authors consider an entertainment system that places small video entertainment sets at every seat for use by each passenger. Each set in the system must be provided with audio and video programming and the electrical power necessary to operate the set. Distribution of programming and power to the sets with a connector for each set would cause reliability and maintenance problems and hinder timely cabin reconfiguration. The entertainment sets can receive audio and video signals through radio-frequency transmission, but distributing power to the sets without using connectors requires a novel approach. The analysis, design, and construction of a prototype connectorless power supply that inductively couples power to the entertainment sets across an air gap is described. An equivalent-circuit model of the supply is developed, and laboratory measurements performed on the prototype are discussed. The prototype unit is shown to be a practical implementation that meets all design requirements. >

Fuel cell power generation system

Abstract: In order to improve the efficiency of a fuel cell power generation system and its ability to adjust to disturbing factors which may occur during operation, a motor driven compressor for providing reaction air to the fuel cell system is driven independently of a power recovery system which recovers energy lost in operational by-products and converts the energy into electrical power. The independent motor driven compressor provides a stable supply of reaction air to the fuel cell and aids in shortening the time necessary for system start up.

Powered communication link

Abstract: A powered communications link between a central controller and a remote substation along a conductor that includes a movable or intermittent contact interacting therebetween includes a power supply located at the central controller for supplying electrical power over the conductor to the remote substation and an electrical power storage device at the remote substation for storing the power supplied over the conductor. Data and power are multiplexed over the conductor by the central controller which periodically stops the application of power to the conductors to permit a transmitter at the remote substation to send data to the central controller. A switch at the remote substation connects the power storage device to the conductor when power is being sent and disconnects it at all other times.

Drive system for turbocharger with rotary electric machine

Abstract: A drive system for a turbocharger installed in an internal combustion engine and combined with a rotary electric machine has a generator drivable by an output power of the engine. When the rotary electric machine operates as an electric motor depending on operating conditions of the engine, the generator is driven to generate electric power that is supplied to the rotary electric machine.

Method of controlling the electric power supplied to a modem

Abstract: A method is disclosed for controlling the supply or electric power to a modem in a data communication interface circuit. A power supplying and blocking circuit is additionally combined with the interface. The power supplying and blocking circuit which is controlled by a controller supplies only the controller and a ring detector of a data access circuit with the electric power when the interface circuit is placed in a stand-by mode. The modem is supplied with power only when transmitting or receiving data.

Power conversion system with stepped waveform inverter having prime mover start capability

Abstract: A power conversion system is operable in a generating mode to convert motive power developed by a prime mover into electrical power and in a starting mode to convert electrical power developed by a source of AC power into motive power for starting the prime mover. The system includes a rectifier having an output coupled to a DC link, first and second inverters, each coupled to the DC link and transformer including first and second sets of primary windings and a set of secondary windings wherein the second set of primary winding is coupled to an output of the second inverter. Contactors are provided for coupling the rectifier to the generator armature windings and the first set of primary windings to an output of the first inverter so that AC power produced by the generator is converted into DC power on the DC link and the DC power is converted into fixed frequency AC power which is developed in the set of secondary windings. The contactors are operable in the starting mode to couple the source of AC power to the set of secondary windings, the first set of primary windings to the rectifier and the output of the first inverter to the generator armature windings so that the AC power induced in the first set of primary windings due to application of AC power to the set of secondary windings is converted into DC power on the DC link and the DC power is converted into AC power at a controlled voltage and frequency which is applied to the generator armature windings.

Fuel cell power generating apparatus and method for controlling the apparatus

Abstract: An electric power supplied to an electric load (24) is determined and the current (i FC ) outputted from a fuel cell part (7) is controlled in accordance with a load power signal (701) which corresponds to the detected result. A fuel cell output following the variation of the power load (24) can be obtained by controlling the amounts of a starting material (41) to be reformed, a reformed fuel (42) and an air (43) to be supplied based on this output current. When the power load (24) is at a low level, the foregoing output from the fuel cell is also supplied to a heating portion (10) for heating the fuel cell part so as not to reduce the current (i FC ) outputted from the fuel cell part. Since the output current is not reduced, it is possible to prevent an extreme increase in the electrode voltage of the fuel cell part (7) and hence the deterioration of the electrode is reduced.

The Power Production Operation of Solar One, the 10 MWe Solar Thermal Central Receiver Pilot Plant

Abstract: Solar One, the 10 MWe Solar Thermal Central Receiver Pilot Plant near Barstow, Calif., completed a three-year period of power production testing in July 1987. During this period the plant's capacity factor, system efficiency, and availability were studied to assess the operational capability of Solar One to reliably supply electrical power. The long-term performance of keyplant components, such as the heliostats and the receiver, was also studied. During the three years of power production operation, Solar One achieved increases in capacity factor, system efficiency, and availability. Heliostat operation was reliable, and only small amounts of mirror corrosion were observed.

Automatic charger capable of charging several batteries

Abstract: An automatic charger is provided capable of charging several removable batteries comprising a block for supplying electric power from the mains and several battery charging modules. It comprises at least one electric connection and fixing rail on which the power supply block and the charging modules are connected and rigidly and removably fixed, with means for automatically controlling initiation and stopping of charging, with signalling.

Miniature low-power/high-voltage thermoelectric generator

Abstract: The fabrication of a miniature low power/high voltage thermoelectric convertor is described. The device which has arisen out of a requirement of the British gas industry for an autonomous source of electrical power for use in consumers' gas monitoring systems, generates fractions of a microwatt at several volts.

Light-energized electronics energy management system

Abstract: An irrigation controller is powered for all normal operations by light incident upon an 18 square inch photovoltaic module(PVM). Electrical power from the photovoltaic module is stored in high performance ''super'' capacitors (SC). A transportable battery power source is connected (14) to the controller (1) to power its communication, such as for manual exercise and/or the loading of irrigation control programs. The external battery power source leaves the capacitor power storage recharged at the conclusion of each communication episode. The irrigation controller electronics, save for a real time clock that is updated, are not provided with a timing signal, and thereby consume almost no energy, save for brief millisecond sporadic time intervals of scheduled irrigation control. Capacitor power storage is approximately 6.5 mWH. Worse case photovoltaic energy production is 7.6 mWH daily. The sporadically operative irrigation controller uses less than 6.4 mWH per day, with remaining energy expended on up to 128 ultra-low-power valve actuations per day.

Thermal protection method for a power device

Abstract: A thermally protected power transistor comprising a first chip which includes a power transistor and a second chip which includes protection circuitry. The second chip has a plurality of metallic bumps formed thereon which are coupled to various portions of the protection circuitry, wherein at least one metallic bump serves as a thermal couple. The protection circuitry chip is mounted upside down on the power transistor chip and coupled to the power transistor chip by the metallic bumps. The metallic bumps serve to provide electrical power for the protection circuitry, to couple control signals between the protection circuitry and the power transistor, and to couple thermal information from the power transistor to the protection circuitry.

Refrigerating system for use in vehicle with engine which enables selective use of commercial ac power source and a generator driven by the engine for driving a refrigerant compressor

Abstract: A cooling system including a refrigerant compressor for use in a vehicle for cooling a refrigerated compartment includes a hermetic type compressor containing a DC brushless motor as a compressor driver. An electric generator is actuated by the engine of the vehicle to generate AC electric power which is, in turn, rectified by a rectifier to produce DC electric power for driving the DC brushless motor. A switch is provided to switch over from the electric generator to a commercial AC electric power source. The commercial AC electric power is rectified by the rectifier to supply DC electric power. Thus, the compressor can be driven by a commercial AC electric power source when the engine is stopped. In order to achieve accurate temperature control in the refrigerated compartment when the engine is running, the amount of AC electric power generated by the electric generator is controlled. Further, when the engine is stopped, the amount of rectified commercial electric power delivered to the DC electric motor is controlled.

Battery heating system using instantaneous excess capacity of a vehicle electrical power generating subsystem

Abstract: A charge management system and method, within a vehicle having a battery and generation subsystem, is disclosed which senses the temperature of electrolyte in the cells of the vehicle battery and the voltage across the terminals of the battery. The voltage indicates the probability of the existence of excess electrical capacity from the vehicle generation subsystem. In response to a cold temperature and excess power, the system uses the excess power of the vehicle generation subsystem to heat the battery to a desired level. Once the battery reaches the desired temperature level, the system dicontinues the heating of the battery. In the event that there is not excess power, then the system, by maintaining the battery heating element in an off position, does not interfere with the charging of the battery.

Electronically commutated motor driven apparatus

Abstract: An apparatus for pumping fluid such as an integral pump/motor is provided. A housing having an inlet and an outlet has a rotatable assembly including an impeller located within and adapted to rotate within the housing to move fluid through the housing from the inlet to the outlet. Secured to the exterior of the housing is a stationary assembly for applying an electromagnetic field through the housing to and around the impeller to rotate the impeller and thereby to cause it to move fluid through the housing. The apparatus is for use in a cooling system, such as a cooling system of an automobile engine, to pump fluid through the cooling system. A temperature sensor is provided for sensing the temperature of the fluid within the cooling system. An electronic control, responsive to the temperature sensor, supplies electrical power to stationary assembly. Also, a method of circulating fluid within a system, such as a cooling system of an automobile engine, is disclosed. An electromagnetic field is applied through a housing to and around a rotatable assembly including an impellar located in the housing thereby to axially rotate the impeller and cause it to move fluid through the housing.

Current supply arrangement having a stand-by mode featuring low power consumption

Abstract: A current supply arrangement, for supplying at least one load with electric energy from a source, includes a switching stage for optionally switching-on the load according to a switching signal applied thereto and a control circuit which, in its switched-off state, cuts the supply of energy to the switching stage and, to the load and in its switched-on state, controls the energy supply to at least the switching stage. Current supply arrangements of such a type are used more specifically in television sets having remote control for "normal operation" and a "stand-by mode". So as to obtain for this arrangement the advantages of the "stand-by mode" and, on the other hand, to reduce the electrical power consumed and also the number of modules loaded by heating or voltage charges, the switching signal is also applied to the control circuit for switching between the switched-off and the switched-on states.

Apparatus for optical power transmission and optically powered system

Abstract: An apparatus for optical power transmission capable of reducing a number of photo cells and improving a power transmission efficiency, and an optically powered system using the apparatus capable of maximizing lifetime of light sources. The apparatus includes an alternating current transformer for transforming the electric power to a desired level for a load. The system further includes a device for detecting magnitude of the electric power, and a device for controlling an amount of light emission by the light source in accordance with the detected magnitude of the electric power such that the magnitude of the electric power to be given to the load is maintained to be substantially constant.

Control device for heater for oxygen sensor operative to correct target resistance with reference to standard power supply thereto

Abstract: For controlling supply of electric power to a heater for an oxygen sensor for detecting oxygen in an exhaust system of an internal combustion engine so as to maintain the electric resistance of the heater to a target value therefor, the target value is corrected based upon detection of the amount of electric power supplied to the heater so that difference between the detected amount of electric power supplied to the heater and a standard value therefor is cancelled.

Power converter system

Abstract: An electrical apparatus for use with a motor vehicle electrical system, which includes an engine-driven alternator, provides a switching circuit for switching the system between a normal-power state and a high-power state. In the normal-power state, the apparatus provides the nominal electrical power needed by the vehicle electrical system and battery. In the high-power state, the apparatus causes the engine-driven alternator to produce a higher voltage and a higher power output for external loads, while still providing the nominal electrical power for the vehicle electrical system and the vehicle battery. In the normal-power mode of operation, the vehicle voltage regulator sees the full voltage generated by the vehicle alternator. In the high-power mode of operation, the vehicle voltage regulator sees only a reduced portion of the full voltage generated by the vehicle alternator. The increased power output from the alternator can be rectified into a high-voltage DC current or can be converted to 60 HZ 110-volt AC power by means of a cycloconverter, for example. A control circuit senses load current in the high-power mode of operation and causes the engine to operate at an increased speed to maintain the increased power output. The control circuit reduces the engine speed to idling speed when there is no load current.