Abstract: Electrolytic filter capacitors are frequently responsible for static converter breakdowns. To predict these faults, a new method to set a predictive maintenance is presented and tested on two types of converters. The best indicator of fault of the output filter capacitors is the increase of ESR (equivalent series resistance). The output-voltage ripple /spl Delta/V/sub o/ of the converter increases with respect to ESR. In order to avoid errors due to load variations, /spl Delta/V/sub o/ is filtered at the switching frequency of the converter. The problem is that this filtered component is not only dependent on the aging of the capacitors, but also on the ambient temperature, output current, and input voltage of the converter. Thus, to predict the failure of the capacitors, this component is processed with these parameters and the remaining time before failure is deduced. Software was developed to establish predictive maintenance of the converter. The method developed is as follows. First, a reference system including all the converter parameters was built for the converter at its sound state, i.e., using sound electrolytic filter capacitors. Then, all these parameters were processed and compared on line to the reference system, thereby, the lifetime of these capacitors was computed.

Abstract: A power supply detects power requirements of an electrical device and configures itself to provide the correct power to the device. By using a connector that isolates the device from its battery, the power supply can provide power to the device, recharge the battery, recharge the battery while at the same time providing power to the device, or provide power to the device while preventing the battery from being recharged. A switch used with the connector creates various circuits and is controllable by the power supply, the electrical device, by signals from the electrical device, or by a third device. The power supply may provide power to a plurality of devices and may be used with other power supplies to form a power grid. A master control unit receives inputs from each of the power supplies and controls the delivery and supply of power being the power supplies.

Abstract: Switching circuits, operating at high frequencies, have led to considerable reductions in the size of magnetic components and power supplies. Nonsinusoidal voltage and current waveforms and high-frequency skin and proximity effects contribute to power transformer losses. Traditionally, power transformer design has been based on sinusoidal voltage and current waveforms operating at low frequencies. The physical and electrical properties of the transformer form the basis of a new design methodology while taking full account of the current and voltage waveforms and high-frequency effects. Core selection is based on the optimum throughput of energy with minimum losses. The optimum core is found directly from the following transformer specifications: frequency; power output; and temperature rise. The design methodology is illustrated with a detailed design of a push-pull power converter.

Abstract: A method and apparatus for supplying contactless power. Electrical power is transferred from a power source (100) to a load (500) through a primary energy converter that can be connected to the power source, through a primary inductive loop connected to the magnetically coupled to the primary (200) inductive loop, and then to a secondary energy converter. The power factor for the transfer of electrical energy is one. Multiple loads can receive power from the power source end, where the loads are located in zones, collisions between the loads can be prevented.

Abstract: Recently, clean electric power generation systems have attracted a great deal of social attention to exploit clean energy resources such as solar arrays, wind generators, fuel cells, etc. In this case, the multiple-input DC-DC power converter is useful to combine the several input power sources and to supply the regulated output voltage for the load. The novel solar cell power supply system using the buck-boost type two-input DC-DC converter is proposed, in which the solar array and the commercial AC line are exploited as power sources and they are combined by the two input windings of the energy-storage reactor. Also, its operation principle and performance characteristics are discussed. Furthermore, the solar cell optimum operating point tracker is proposed and examined. It is confirmed by the experiment that the proposed solar cell power supply system has the excellent performance characteristics.

Abstract: An uninterruptible power supply is disclosed in which the backup energy source is connected to the power supply of the protected computer by means of a bi-directional power converter. This converter operates without sensing circuitry, relays, or switches, operating continuously when a load is present in either charging or discharging the backup energy source. This uninterruptible power supply can be placed within the available space of a functioning standard computer power supply enclosure, and may be configured so that it may be replaced during normal computer operation (i.e. it is "hot swappable"). Methods are described to interface the uninterruptible power supply to the computer, providing mutual control and communication. The device may be also used to power devices requiring external DC power, which are commonly found in association with computer operations.

Abstract: A universal ballast control circuit allows a universal ballast to accommodate a gas discharge lamp within a relatively wide wattage range using a low-speed microcontroller. The control circuit drives the ballast to start, run and dim a particular lamp type by providing a control voltage signal to a conventional inverter MOSFET driver to effect dynamic and selective changes in the duty cycle and the frequency of the inverter signal. In one aspect of the invention, the control circuit comprises a generator for generating a periodic analog voltage signal, a source for producing a DC voltage signal, a controller which includes a low-speed microcontroller for varying the frequency of the periodic analog voltage signal and the magnitude of the DC voltage signal, and a comparator for comparing the periodic analog voltage signal and the DC voltage signal to produce a control voltage signal. In another aspect of the invention, the control circuit comprises a generator for generating a periodic analog voltage signal, a controller for controlling the shape of the periodic analog voltage signal, and a comparator for comparing waveforms of the periodic analog voltage signal with the waveforms of two DC threshold voltages to generate a control signal. The present invention allows for the control circuit to be powered by a power supply signal either derived from an inverter half-bridge MOSFET driver, extracted from a boost inductor of the boost converter or generated by an appropriately configured dedicated miniature switch mode power supply. Finally, control circuit can be utilized to drive PFC circuity in a feedback configuration to regulate the level of boost converter output voltage signal.

Abstract: A single-phase high-efficiency near-unity power-factor (PF) half-bridge boost converter circuit, which has been proposed earlier by other researchers, is presented with detailed analysis. This converter is capable of operating under variable PF. However, the focus of this paper is in achieving unity PF operation only. The efficiency of this circuit is high because there is only one series semiconductor on-state voltage drop at any instant. The existence of an imbalance in the voltages of the two DC-link capacitors, which was noted before, is confirmed here. The cause for the imbalance is analyzed using appropriate models, and a control method to eliminate it is discussed in detail. Analysis and design considerations for the power circuit using the fixed-band hysteresis current control (HCC) technique are provided. The analytical results are verified through simulation using switched and averaged circuit models of the scheme and also through experimental work. At 90-V AC input and 300-W 300-V output, the experimental prototype demonstrates an efficiency of 96.23% and a PF of 0.998. This converter, with its relatively high DC-output voltage, is well suited for the 110-V utility supply system. A circuit modification for universal input voltage range operation is also suggested.

Abstract: Over the last decade, significant increases in capacitor performance, especially in reliability and energy/power densities, have been achieved for energy discharge applications in plasma science and fusion research applications through a combination of advanced manufacturing techniques, new materials, and diagnostic methodologies to provide requisite life-cycle performance for high energy pulse applications. Recent innovations in analysis of aging are introduced for predicting component performance and fault tolerance, especially relevant for very high energy storage applications necessary for next generation simulators, electrically energized fusion research machines, and advanced high power electronics for commercial, industrial, and military applications. Included in this study will be developments in capacitor technologies for electronics filtering and resonant energy transfer applications, as well as multisecond energy reservoir applications for uninterruptible power sources and the like. Next generation power electronics, driven by advances in solid state switching technologies, will require reduced capacitor dissipation factor by 1/3 to 1/10 at the same cost, particularly for ac applications. In addition, higher power electronics will require robust high frequency mica capacitor technology for >300°C operation, up to 5 kV. The increasing expansion of the motor drive and industrial switched mode power supply (SMPS) market will be driven in cost by the availability of electrolytic capacitors of 750-850 Vdc ratings, at 450 Vdc cost and size. New formation processes and electrolytes are anticipated to be needed to achieve these extended performance levels. At higher frequencies, advanced power electronics drives the need for lower equivalent series resistance (ESR) « 0.1% to 100 MHz, multimicrofarad value solid tantalum capacitors, having fail-safe surface mount configurations. Emerging power electronics applications in the millisecond and longer time are projected to have a broad application need for electrochemical chemical double layer capacitors, especially for compact sizes as this technology has the potential of achieving energy densities of many 20 kJ/kg for discharge times of tens of seconds. The prismatic power conditioning system, designed to be compliant with the available volume and surfaces into which it is to be placed, is described in some detail. It permits flexibility for the design engineer to optimize the design without having to allocate a specific space for the power conditioning system or subcomponents. Such prismatic geometry power and power conditioning systems are becoming commercially feasible in the low power consumer and industrial regime because of dramatic advances in multichip module switching, energy storage, and planarized interconnections. This work builds on assessing the applicability of these technologies to the megawatt-class average power, power electronics regime. Higher power density prismatic power electronics enables a broad range of applications in the commercial arena in areas such as motor drives, inverters, power quality systems, and mobile power systems.

Abstract: A lighting circuit supplies an input voltage from a battery to a discharge lamp after the input voltage has been sent via a DC power supply section to a DC-AC converter. This lighting circuit comprises a lighting detector for detecting if the discharge lamp is lighted, an input-voltage monitor circuit for detecting the input voltage to the DC power supply section and checking if the input voltage lies within an allowable range, and a stable power supply circuit and a switch section for supplying power to the discharge lamp or inhibiting the power supply thereto in accordance with a signal from the input-voltage monitor circuit. The input-voltage monitor circuit performs variable control on a reference value to be compared with the input voltage, in accordance with a signal from the lighting detector.

Abstract: A design-oriented analysis of the microwave transmission-line class-E amplifier is presented. Experiments and harmonic-balance circuit simulations verify the theoretical equations which predict class-E-amplifier output power, maximum frequency of operation, and dc-RF conversion efficiency. Experimental results at 0.5, 1,2, and 5 GHz are presented. At 0.5 GHz, 83% drain efficiency and 80% power-added efficiency (PAE) are measured, with an output power of 0.55 W, using the Siemens CLY5 MESFET. These results are compared to a class-A and class-F power amplifier using the same device. At 5 GHz, 81% drain efficiency and 72% PAE are measured, with an output power of 0.61 W, using the Fujitsu FLK052WG MESFET. Finally, the 5-GHz class-E power amplifier is successfully integrated into an active-antenna array, demonstrating power combining of four elements with an 85% power-combining efficiency. At 5.05 GHz, the class-E power-amplifier antenna array delivers a total of 2.4 W of output power, with a dc-RF conversion efficiency of 74% and a PAE of 64%.

Abstract: A driving system has been designed for phased array ultrasound applicators. The system is designed to-operate in the bandwidth 1.2 to 1.8 MHz, with independent channel power control up to 60 W (8 bit resolution) for each array element. To reduce power variation between elements, the system utilizes switching regulators in a feedback loop to automatically adjust the DC supply of a class D/E power converter. This feedback reduces the RF electrical power variation from 20% to 1% into a 16 element array. DC-to-RF efficiencies close to 70% for all power levels eliminates the need for large heat sinks. In addition to power control, each channel may be phase shifted 360/spl deg/ with a minimum of 8 bit resolution. To ensure proper operation while driving ultrasound arrays with varying element sizes, each RF driving channel implements phase feedback such that proper phase of the driving signal is produced either at the amplifier output before the matching circuitry or after the matching circuitry at the transducer face. This feedback has been experimentally shown to increase the focal intensities by 20 to 25% of two tested phased arrays without array calibration using a hydrophone.

Abstract: A power supply system has a power input to receive input power from a power source, a power output to provide output power to a load, at least one battery module having a battery output that provides battery power, at least one power module coupled to the power input to receive the input power, coupled to the battery output to receive the battery power and coupled to the power output to provide the output power, a controller, coupled to the at least one power module, constructed and arranged to monitor and control the output power from the at least one power module, and a redundant controller, coupled to the at least one power module and to the controller, constructed and arranged to provide redundant monitoring and controlling of the output power from the at least one power module.

Abstract: A system and method for providing an uninterrupted supply of power to a critical load includes at least two uninterruptible power supply UPS modules that receive power from separate utility sources. A controller controls the UPS modules so that the output power from one UPS module is substantially in-phase with the output power from the other UPS module. As a result, the output powers from the UPS modules can be combined with one another to provide a sufficient source of uninterruptible power to the critical load regardless of the phase difference in the power provided by the separate utility sources.

Abstract: A PWM voltage rectifier has useful characteristics on its DC and AC sides. On its DC side, a DC-link unidirectional voltage is obtained and bidirectional power transfer capability is possible by reversing the flow direction of the DC-link current. On its AC side, near sinusoidal current waveforms and AC four-quadrant operation can be obtained, leading to high-quality power being exchanged between the power converter and the mains. The use of AC filters becomes unnecessary. The rectifier DC voltage must be regulated to a constant value. In this paper, three solutions for the DC voltage control are presented. In the first solution, the DC voltage is controlled by acting upon the quadrature component of the power converter fundamental Park's voltages with relation to the mains voltages. Slow responses are necessary because of stability reasons. Also, load power variations produce both active and reactive power variations in the power converter AC side. To improve the DC voltage response, a second control solution is presented. The power converter currents in Park's coordinates must be controlled. The DC voltage is controlled by controlling the direct Park's current component and, thus, acting only on the active power of the converter AC side. Faster responses are achieved. In this case, load power variations do not produce reactive power variations in the converter AC side. The third control solution is a simplified version of this last one. Experimental results from a 2 kVA IGBT-based prototype showing good system dynamic performance are presented.

Abstract: In this paper, nonlinear-carrier (NLC) control is proposed for high-power-factor rectifiers based on flyback, Cuk, Sepic, and other up-down power converters operated in the continuous conduction mode (CCM). In the NLC controller, the switch duty ratio is determined by comparing a signal proportional to the integral of the switch current with a periodic nonlinear-carrier waveform. The shape of the NLC waveform is determined so that the resulting input-line current follows the input-line voltage, as required for unity power factor rectification. A simple exponential carrier waveform generator is described. Using the NLC controller, input-line voltage sensing, error amplifier in the current-shaping loop, and multiplier/divider circuitry in the voltage feedback loop are eliminated. The simple high-performance controller is well suited for integrated-circuit implementation, Results of experimental verification on a 150 W flyback rectifier are presented.

Abstract: A high frequency power supply (28) for applying electrical energy to a target site on or within a patient's body in the presence of electrically conductive fluid. In one embodiment, the power supply (28) includes an electrical output driver (342), an output current sensor (302) detecting the current output from the driver, and a power limiting device (330) coupled to the current sensor. During normal conditions the power limiting device (330) operates on a continuous basis. When current output exceeds a predetermined threshold level, the power limiting device (330) is adapted to reduce power on the ouput driver to a standby mode. The power limiting device (330) operates on a periodic detection or duty cycle when in the standby mode. The power limiting device (330) switches into the standby mode to prevent excessive power drains.

Abstract: While existing techniques are capable of automatically identifying and classifying various types of distribution-level power quality disturbances, they do not provide any information about the locations of the disturbance sources. This paper shows that it is possible to use sampled voltage and current waveforms to determine on which side of a recording device a disturbance originates. This is accomplished by examining the energy flow and peak instantaneous power for both capacitor energizing and voltage sag disturbances. We demonstrate the technique by testing it on both ATP-generated waveforms and actual field disturbance data. In both cases, we are able to accurately determine on which side of a recording device the disturbance originates. If enough recording devices are available in a network, the individual readings can be collectively used to pinpoint the locations of disturbance sources.

Abstract: The dynamic properties of the buck converter with a constant power load are studied in this paper. The line-to-output and control-to-output transfer functions are derived, for voltage mode control and current mode control, in continuous conduction mode and discontinuous conduction mode. A comparison with the case of a resistive load is made in each case.

Abstract: A method and system for detecting a nonfunctional element in an ink jet printhead is disclosed. The ink jet printer system includes: a switching power supply, coupled to the inkjet printhead, for supplying power to the printhead; an output capacitor, coupled to an output of the switching power supply, for storing a dc voltage therein; a bleed resistor, coupled in parallel to the output capacitor, for discharging current from the output capacitor; an output shifting circuit, coupled to the switching power supply, for shifting the dc voltage level across the output capacitor between a low state and a high state; and a sensor, coupled to the output of the switching power supply, for detecting when the switching power supply is switching, wherein an element of the printhead is tested by measuring a test current discharging from the output capacitor when the element is activated and comparing the measured test current with a reference current which discharges from the output capacitor through the bleed resistor. The method includes: supplying regulated power to the printhead; storing the regulated power in a capacitor so as to provide a dc voltage across the capacitor; shifting the dc voltage level stored in the capacitor between a low state and a high state; measuring a test current discharging from the capacitor when an element of the printhead is activated; measuring a reference current discharging from the capacitor through a bleed resistor, when no elements of the printhead are activated; and comparing the measured test current with the reference current.

Abstract: A switched-mode power supply circuit having an operating mode and a stand-by mode. The switched-mode power supply circuit includes a transformer and a controllable switch connected to a primary winding of the transformer for switchably connecting the primary winding to a source of d.c. voltage. In the stand-by mode, the switched-mode power supply circuit is arranged to switchably connect the primary winding to the d.c. voltage source in bursts which occur at a low frequency. Between each of the bursts, an auxiliary capacitor, which is ordinarily charged by an auxiliary winding during switching of the controllable switch, is now charged by a start-up current source contained in a controller for controlling the controllable switch.

Abstract: A new input current shaper is proposed in this paper. The operating principle is based on the connection of a voltage source and a loss-free resistor (LFR) between the input rectifier and the bulk capacitor in a conventional switching-mode power supply with no power factor correction. Both the voltage source and the LFR are obtained as an additional output from the power converter's transformer. This additional output is a forward-type scheme with one extra inductor. With the final topology, a good tradeoff between capacitor voltage, re-cycling energy and harmonic content can be established in order to comply with IEC 1000-3-2 at different power levels.

Abstract: In a photoelectric conversion device having a plurality of pixel cells each of which includes a photoelectric conversion element, a field effect transistor having the gate area for storing signal charge generated by the photoelectric conversion element and the source-drain path for outputting a signal corresponding to the signal charge stored in the gate, a first power supply line for supplying electric power to the field effect transistor, and a first switch connected between the field effect transistor and the first power supply line, when a reset voltage for resetting the gate of the field effect transistor is Vsig0, a threshold voltage of the field effect transistor is Vth, current flowing through the field effect transistor is Ia, a voltage applied via the first power supply line is Vc1, and a series resistance of the first switch is Ron, each pixel cell is configured to satisfy a condition determined by Vc1−Ron×Ia>Vsig0−Vth.

Abstract: A high efficiency lighting system maintains normal lighting conditions by lighting fixtures requiring DC electrical power. A power control device receives AC electrical power from a public utility converts AC power to DC power and delivers low voltage DC electrical power to lighting fixtures. A standby battery is provided to maintain power during power outages. Optionally, a photovoltaic DC electrical power source may be connected to the power control device, to provide alternate DC electrical power. In a further embodiment, a gas driven cogenerator unit may supply DC electrical power.

Abstract: An adaptive power supply for an avalanche photodiode (APD) is used to determine an optimum bias voltage. Without an optical signal input the adaptive power supply applies a swept voltage to the APD while monitoring the photodiode current. When breakdown occurs, the voltage is noted and the bias voltage from the adaptive power supply is set at a specified offset below the breakdown voltage. Where a source of optical digital data signal is present, it is coupled to the input of the APD via a programmable optical attenuator. The electrical digital signal output from the APD is input to a bit error rate counter, the output of which is monitored. For different optical power levels the APD bias voltage is swept by the adaptive power supply, determining a constant power level curve over which the bit error rate is virtually zero. This is repeated for a plurality of optical power levels, the resulting family of curves defining a region within the bit error rate is virtually zero. The adaptive power supply is set to a value that falls within the virtually zero bit error rate region for the expected optical power level input.

Abstract: In differential protection schemes for electrical power systems there is a need to employ a synchronization technique to enable time alignment of local terminal current with received current from a remote terminal in order reliably to operate the differential protection scheme. A method of determining a communication time delay in a communication network between a local terminal and each of a plurality of remote terminals in a multi-terminal multi junction electrical power system includes: (a) calculating a respective initial communication time delay between each remote terminal and the local terminal; (b) calculating a respective junction time delay between respective first, second and third pairs of adjacent junctions; and (c) correcting the calculated initial communication time delay of each remote terminal spaced from the local terminal by two or more junctions according to each corresponding junction time delay arising between the or each said remote terminal and the local terminal.

Abstract: A DRAM includes first to third voltage lowering circuits for lowering a power supply voltage supplied from the exterior and supplying the lowered voltage to an internal circuit. The first to third voltage lowering circuits are separately provided. The first voltage lowering circuit is a feedback type circuit having a P-channel MOS transistor. The first voltage lowering circuit is an exclusive circuit for creating a first potential by lowering the power supply voltage supplied from the exterior and supplying a thus created lowered power supply voltage to a RAS signal input buffer, CAS signal input buffer and WE signal input buffer. The second voltage lowering circuit is a feedback type circuit having a P-channel MOS transistor or source follower type circuit having an N-channel MOS transistor. The second voltage lowering circuit is an exclusive circuit for creating a second potential by lowering the power supply voltage supplied from the exterior and supplying a thus created lowered power supply voltage to a V BL generating circuit for generating a bit line precharge potential and a V PL generating circuit for generating a cell plate potential. The third voltage lowering circuit is a source follower type circuit having an N-channel MOS transistor. The third voltage lowering circuit is a circuit for creating a third potential by lowering the power supply voltage supplied from the exterior and supplying a thus created lowered power supply voltage to all of the other internal circuits except the above circuits.

Abstract: In the particular embodiments described, an unlimited voltage static power converter includes an array of multi-level phase drivers consisting of a plurality of H-bridge power modules connected in series. The midpoint node of the series-connected power semiconductors is connected to corresponding midpoint nodes in adjacent H-bridges to achieve a desired high output voltage using available power switch ratings. A three-dimensional multi-level, multi-phase, multi-circuit array of H-bridges permits the use of the static power converter for high power applications, while providing a high degree of power quality. The power semiconductor switches are operated in accordance with a two-dimensional interleaved pulse width modulation algorithm which produces a waveform with a switching frequency that can be more than an order of magnitude higher than the switching frequency of a single power switch. PWM complementary triangle carrier waves are used for individual PWM control of each H-bridge in each multi-level phase driver, resulting in a two-dimensional interleaved control algorithm. Injection of harmonic or non-harmonic content into the PWM reference waveform further reduces harmonic and non-harmonic content of the output voltage waveforms. Part-load efficiency is increased using unique load partitioning methods, five of which are described herein.