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Multilevel converters -- A new breed of power converters

Description: Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc capacitor voltages. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The techniques to balance the voltage between different levels normally involve voltage clamping or capacitor charge control. There are several ways of implementing voltage balance in multilevel converters. Without considering the traditional magnetic coupled converters, this paper presents three recently developed multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded-inverters with separate dc sources. The operating principle, features, constraints, and potential applications of these converters will be discussed.
Date: September 1, 1995
Creator: Lai, J.S. & Peng, F.Z.
Partner: UNT Libraries Government Documents Department

Main amplifier power conditioning for the National Ignition Facility

Description: The National Ignition Facility (NIF), being built at Lawrence Livermore National Laboratory (LLNL) will utilize a 18 MJ glass laser to study inertial confinement fusion This laser will be driven by a power conditioning system which must simultaneously deliver over 260 MJ of electrical energy to the nearly 7700 flashlamps The power conditioning system is divided into independent modules that store, shape and deliver pulses of energy to the flashlamps The NIF power conditioning system which is being designed and built by Sandia National Laboratory (SNL) in collaboration with LLNL and industrial partners, is a different architecture from any laser power conditioning system previously built at LLNL This particular design architecture was chosen as the most cost- effective way to reliably deliver the large amount of energy needed for NIF This paper will describe the development and design of the NIF power conditioning system It will discuss the design objectives as well as the key design issues and technical hurdles that are being addressed in an ongoing component development and system validation program being supported by both SNL and LLNL.
Date: June 8, 1998
Creator: Newton, M.
Partner: UNT Libraries Government Documents Department

Resonant snubber based soft-switching inverters for electric propulsion drives

Description: This paper summarizes recently developed soft-switching inverters and proposes two alternative options for electric propulsion drives. The newly developed soft-switching inverter employs an auxiliary switch and a resonant inductor per phase to produce a zero voltage across the main switch so that the main switch can turn on at the zero-voltage condition. Both the auxiliary switch and the resonant inductor are operating at a fractional duty, and thus are small in size as compared to the main inverter circuit components. Operation modes in a complete zero-voltage switching cycle for the single-phase soft-switching inverter are described in detail with graphical explanations. The circuit operation was first verified by a computer simulation and then tested with an 1-kW single-phase and an 100-kW three-phase inverters. Experimental results are presented to show the superior performance in efficiency improvement, EMI reduction, and dv/dt reduction of the proposed soft-switching inverters.
Date: May 1, 1996
Creator: Lai, J.S.
Partner: UNT Libraries Government Documents Department

Instantaneous phasor method for obtaining instantaneous balanced fundamental components for power quality control and continuous diagnostics

Description: This paper introduces an instantaneous phasor method that considers three phases simultaneously. This method produces the instantaneous fundamental balanced components of the polluted voltages or currents. A figure shows three-phase voltages that contain 5% of fundamental magnitude for each order of the 3rd, 5th, 7th, 9th and the 11th harmonics, respectively. Additionally, the voltages have 5% unbalance for all voltage components. A 10% fundamental-frequency zero-sequence component, as well as a 10% fundamental-frequency negative-sequence component are also added to the phase voltages. Furthermore, certain high-frequency pulses arbitrarily given at 5% of a 35th order to represent a possible carrier frequency of power electronic circuits are also included.
Date: July 1, 1997
Creator: Hsu, J.S.
Partner: UNT Libraries Government Documents Department

Performance characteristics of an induction linac magnetic pulse compression modulator at multi-kilohertz pulse repetition frequencies

Description: The ETA-II linear induction accelerator utilizes four pulse power conditioning chains. Magnetic pulse compression modulators (MAG1-Ds) form the last stage of each chain. A single power conditioning chain is used to drive the injector; the remaining three are used to drive 60 accelerator cells. Nominal parameters of the MAG1-D are an output voltage of greater than 120 kV, pulse width of 70 ns, and an output impedance of 2 ohms. Our operations goal for ETA-II is stable high average power operation at 5 kHz PRF. We have begun upgrading and characterizing the power conditioning chain on our High Average Power Test Stand (HAPTS). On HAPTS, the pulse to pulse amplitude stability has been improved to less than 0.7% (one sigma) and of order 3-5 ns random jitter about a systematic timing variation. In this paper we describe the status of our work to achieve the this paper we describe the status of our work to achieve the average power operation of ETA-II
Date: May 1, 1991
Creator: Sampayan, S.E.; Chambers, F.W. & Deadrick, F.J.
Partner: UNT Libraries Government Documents Department

Integrated power conditioning for laser diode arrays

Description: This compact modulator has demonstated its ability to efficiently and accurately drive a laser diode array. The addition of the crowbar protection circuit is an invaluable addition to the integrated system and is capable of protecting the laser diode array against severe damage. We showed that the correlation between measured data and simulation indicates that our modulator model is valid and can be used as a tool in the design of future systems. The spectrometer measurements that we conducted underline the imprtance of current regulation to stable laser operation.
Date: June 30, 1995
Creator: Hanks, R.L.; Kirbie, H.C.; Newton, M.A. & Farhoud, M.S.
Partner: UNT Libraries Government Documents Department

Multilevel converters for power system applications

Description: Multilevel converters are emerging as a new breed of power converter options for power system applications. These converters are most suitable for high voltage high power applications because they connect devices in series without the need for component matching. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. To avoid voltage unbalance between different levels, several techniques have been proposed for different applications. Excluding magnetic-coupled converters, this paper introduces three multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded inverters with separate dc sources. The operation principle, features, constraints, and potential applications of these converters will be discussed.
Date: September 1, 1995
Creator: Lai, J.S.; Stovall, J.P. & Peng, F.Z.
Partner: UNT Libraries Government Documents Department

A delta configured auxiliary resonant snubber inverter

Description: A delta ({Delta}) configured auxiliary resonant snubber inverter is developed to overcome the voltage floating problem in a wye (Y) configured resonant snubber inverter. The proposed inverter is to connect auxiliary resonant branches between phase outputs to avoid a floating point voltage which may cause over-voltage failure of the auxiliary switches. Each auxiliary branch consists of a resonant inductor and a reverse blocking auxiliary switch. Instead of using an anti-paralleled diode to allow resonant current to flow in the reverse direction, as in the Y-configured version, the resonant branch in the {Delta}-configured version must block the negative voltage, typically done by a series diode. This paper shows single-phase and three-phase versions of {Delta}-configured resonant snubber inverters and describes in detail the operating principle of a single-phase version. The extended three-phase version is proposed with non-adjacent state space vector modulation. For hardware implementation, a single-phase 1-kW unit and a three-phase 100-kW unit were built to prove the concept. Experimental results show the superiority of the proposed topology.
Date: September 1, 1995
Creator: Lai, J.S.; Young, R.W.; Ott, G.W. Jr.; McKeever, J.W. & Peng, F.Z.
Partner: UNT Libraries Government Documents Department

Development and Testing of the NIF Prototype Module

Description: The NIF Power Conditioning System (PCS) is required to deliver -68 kJ to each of the 3840 flashlamp pairs in the NIF laser in a current pulse with a peak of -500 kA and rise time of- 150 µs. The PCS will consist of 192 modules each of which drive 20 lamp-pairs. Each module will basically be a 6 rnF capacitor bank with a nominal charge voltage of 23.5 kV which is switched by a single pressurized air gas switch to 20 RG-220 cables that are connected to individual lamp loads. In addition each module will have a number of subsystems including; a lamp pre-ionization system, power supplies, isolation circuits, trigger systems, safety dump systems, gas system, and an embedded control system. A module will also include components whose primary function is to limit fault currents and thus minimize collateral damage in faults. In the Prototype Development and Testing effort at Sandia National Laboratories all of these were integrated into a single system and proper fimctionality was demonstrated. Extensive testing was done at nominal operating levels into resistive dummy loads and some testing in fault modes was also done. A description of the system and a summary of testing is given in this paper.
Date: June 25, 1999
Creator: Adcock, J.; Harjes, C.; Mowrer, G. & Wilson, M.
Partner: UNT Libraries Government Documents Department

FANTM: The First Article NIF Test Module for the Laser Power Conditioning System

Description: Designing and developing the 1.7 to 2. 1-MJ Power Conditioning System (PCS) that powers the flashlamps for the National Ignition Facility (NIF), currently being constructed at Lawrence Livermore National Labs (LLNL), is one of several responsibilities assumed by Sandia National Labs (SNL) in support of the NIF Project. The test facility that has evolved over the last three years to satisfy the project requirements is called FANTM. It was built at SNL and has operated for about 17,000 shots to demonstrate component performance expectations over the lifetime of NIF. A few modules similar to the one shown in Fig. 1 will be used initially in the amplifier test phase of the project. The final till NIF system will require 192 of them (48 in each of four capacitor bays). This paper briefly summarizes the final design of the FANTM facility and compares its performance with the predictions of circuit simulations for both normal operation and fault-mode response. Applying both the measured and modeled power pulse waveforms as input to a physics-based, semi-empirical amplifier gain code indicates that the 20-capacitor PCS can satisfy the NIF requirement for an average gain coefficient of 5.00 %/cm and can exceed 5.20%/cm with 24 capacitors.
Date: June 24, 1999
Creator: Hammon, Jud; Harjes, Henry C.; Moore, William B.S.; Smith, David L. & Wilson, J. Michael
Partner: UNT Libraries Government Documents Department

Power conditioning for the National Ignition Facility

Description: A cost-effective, 320-MJ power-conditioning system has been completed for the proposed National Ignition Facility (NIF). The design features include metallized dielectric capacitors, a simple topology, and large (1.6-MJ) module size. Experimental results address the technical risks associated with the design.
Date: May 26, 1994
Creator: Larson, D. W.; Anderson, R. & Boyes, J.
Partner: UNT Libraries Government Documents Department

STATUS OF THE NIF POWER CONDITIONING SYSTEM

Description: The NIF Power Conditioning System provides the pulsed excitation required to drive flashlamps in the laser's optical amplifiers. Modular in design, each of the 192 Main Energy Storage Modules (MESMs) storage up to 2.2 MJ of electrical energy in its capacitor bank before delivering the energy to 20 pairs of flashlamps in a 400 {micro}s pulse (10% power points). The peak current of each MESM discharge is 0.5 MA. Production, installation, commissioning and operation of the NIF Power Conditioning continue to progress rapidly, with the goals of completing accelerated production in late 2007 and finishing commissioning by early 2008, all the while maintaining an aggressive operations schedule. To date, more than 80% of the required modules have been assembled, shipped and installed in the facility, representing more that 240 MJ of stored energy available for driving NIF flashlamps. The MESMs have displayed outstanding reliability during daily, multiple-shift operations.
Date: July 26, 2007
Creator: Arnold, P; Hulsey, S; Ullery, G; Petersen, D; Pendleton, D; Ollis, C et al.
Partner: UNT Libraries Government Documents Department

AN UPDATE ON THE STATUS OF THE NIF POWER CONDITIONING SYSTEM

Description: The National Ignition Facility (NIF) Power Conditioning System provides the pulsed excitation required to drive flashlamps in the laser's optical amplifiers. Modular in design, each of the 192 Main Energy Storage Modules (MESMs) stores up to 2.2 MJ of electrical energy in its capacitor bank before delivering the energy to 20 pairs of flashlamps in a 400 {micro}s pulse (10% power points). The peak current of each MESM discharge is 0.5 MA. Production, installation, commissioning and operation of the NIF Power Conditioning continue to progress rapidly, with the goals of completing accelerated production and commissioning by early 2008, while maintaining an aggressive operation schedule. To date, more than 97% of the required modules have been assembled, shipped and installed in the facility, representing more that 380 MJ of stored energy available for driving NIF flashlamps. The MESMs have displayed outstanding reliability during daily, multiple-shift operations.
Date: September 6, 2007
Creator: Arnold, P A; Hulsey, S; Ullery, G T; Petersen, D E; Pendleton, D L; Ollis, C W et al.
Partner: UNT Libraries Government Documents Department

Predicted Pulsed-Power/Flash-Lamp Performance of the NIF Main Amplifier

Description: The laser glass for the National Ignition Facility (NIF) Main Amplifier system is pumped by a system of 192 pulsed power/flash lamp assemblies. Each of these 192 assemblies consists of a 1.6 MJ (nominal) capacitor bank working with a Pre-Ionization/Lamp Check (PILC) pulser to drive an array of 40 flash lamps. This paper describes the predicted performance of these Power Conditioning System (PCS) modules in concert with flashlamp assemblies in NIF. Each flashlamp assembly consists of 20 parallel sets of lamps in series pairs. The sensitivity of system performance to various design parameters of the PILC pulser and the main capacitor bank is described. Results of circuit models are compared to sub-scale flashlamp tests and to measurements taken in tests of a PCS module driving a flashlamp assembly in the First Article NIF Test Module facility at Sandia National Laboratories. Also included are predictions from a physics-based, semi-empirical amplifier gain code.
Date: June 22, 1999
Creator: Fulkerson, E. Steven; Hammond, Jud; Harjes, Henry C.; Moore, William B.S.; Smith, David L. & Wilson, J. Michael
Partner: UNT Libraries Government Documents Department

Inverter testing at Sandia National Laboratories

Description: Inverters are key building blocks of photovoltaic (PV) systems that produce ac power. The balance of systems (BOS) portion of a PV system can account for up to 50% of the system cost, and its reliable operation is essential for a successful PV system. As part of its BOS program, Sandia National Laboratories (SNL) maintains a laboratory wherein accurate electrical measurements of power systems can be made under a variety of conditions. This paper outlines the work that is done in that laboratory.
Date: April 1, 1997
Creator: Ginn, J.W.; Bonn, R.H. & Sittler, G.
Partner: UNT Libraries Government Documents Department

Ac-dc converter firing error detection

Description: Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal.
Date: July 15, 1996
Creator: Gould, O.L.
Partner: UNT Libraries Government Documents Department

R. Lynette & Associates and Pacific Northwest Laboratory staff exchange: Analysis and evaluation of the application of the Pulse Amplitude Synthesis and Control (PASC) converter in a wind power plant

Description: The main objective of staff exchanges is to facilitate cooperative activities between PNL staff and U.S. private industry. Funding for the projects is provided by the DOE Office of Energy Research Laboratory Technology Transfer Program. Dr. Matthew Donnelly, a Research Engineer in the Applied Physics Center, Initiated a PNL disclosure for Pulse Amplitude Synthesis and Control (PASC) converter intellectual property protection in 1993. PASC converter research at the Pacific Northwest Laboratory (PNL) has been funded through the ETDI LDRD program. Recent work has centered on building the three-phase 20kW laboratory unit, the development of control algorithms and the study of the application of PASC converters in a 25MW wind power plant (through the staff exchange with RLA reported on here). An overview and description of the PASC converter is included as Appendix A.
Date: December 31, 1998
Partner: UNT Libraries Government Documents Department

TRIAC/SCR proportional control circuit

Description: A power controller device which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage to frequency converter controls the reset input of a R-S flip flop, while an 0 crossing detector controls the set input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the reset and set inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations.
Date: December 1, 1997
Creator: Hughes, Wallace J.
Partner: UNT Libraries Government Documents Department

Next-generation three-phase inverters. Phase one annual report, 1996

Description: The PV-MaT 4A subcontract addresses the cost effective manufacture of PV related end-products. Advanced Energy Systems Inc. (AES Inc.) has undertaken NREL contract No. ZAF-4-14271-10, {open_quotes}Next Generation Three Phase Inverter{close_quotes}, to combine leading industry skill with state-of-the-art technologies to realize cutting-edge PV inverter related products. To this end, in phase one of the PV-MaT contract, AES Inc. has made significant inroads toward establishing low cost manufacture of an intelligent controller PV-hybrid product.
Date: July 1, 1997
Creator: Wesley, A. & Wills, R.
Partner: UNT Libraries Government Documents Department

Integrated power management for microsystems

Description: There is a need for a universal power module for microsystems. This module should provide power conditioning, energy storage, and load matching for a variety of energy sources and loads such as microelectromechanical systems (MEMS) and wireless sensors and micro-robots. There are a variety of potential ambient and human powered energy sources, which can supply some of the power needs of the military. The challenge is to capture these available sources of electrical energy and condition them to meet the voltage, current, and overall power demands of field-deployable microelectronics and MEMs-based devices such as wireless sensors and micro-robots. Most natural and man-made energy sources found in the environment have a low specific power and are not generally available on a continuous basis. Likewise, human-based energy sources must be optimally managed to meet the power needs in the field. Therefore, a power supply must have the ability to capture the available energy and store it in such a manner to be useful to meet the mission requirements of the device that is connected to the source. It must continuously monitor the status of energy stored and determine the expected demands of the device. A microelectronics-based power management chip can be developed to meet these objectives. The major challenge in realizing this concept will be the design of an intelligent power-conditioning chip that consumes a minimum of power to perform the functions of power conditioning, storage, load matching, and status monitoring. The prototype power conditioning integrated circuit would be capable of delivering a peak power of 100 mW at 5 V. The nominal operating condition would be a very low duty cycle for a relatively high power load, and a low-power source available for long periods of time, or a moderate-power source available intermittently.
Date: December 1, 1997
Creator: Fry, D.N.; Wintenberg, A.L. & Bryan, B.L.
Partner: UNT Libraries Government Documents Department

FANTM, the First Article NIF Test Module

Description: Designing and developing the 1.7 to 2.1-MJ Power Conditioning System (PCS), that will power the flashlamps of the main and power amplifiers for the National Ignition Facility (NIF) lasers, is one of several responsibilities assumed by Sandia National Labs (SNL) in support of the NIF Project. Maxwell Physics International has been a partner in this process. The NIF is currently being constructed at Lawrence Livermore National Labs (LLNL). The test facility that has evolved over the last three years to satisfy the project requirements is called FANTM, for the First Article NIF Test Module. It was built at SNL and operated for about 17,000 shots to demonstrate component performance expectations over the lifetime of NIF. A few modules similar to the one shown in Fig. 1 will be used initially in the amplifier test phase of the project. The final full NIF system will require at least 192 of them in four capacitor bays. This paper briefly summarizes the final design of the FANTM facility and compares its performance with the predictions of circuit simulations for both normal operation and fault-mode response. Applying both the measured and modeled power pulse waveforms as input to a physics-based, semi-empirical amplifier gain code indicates that the 20-capacitor PCS can satisfy the NIF requirement for an average gain coefficient of 5.00 %/cm and can exceed 5.20 %/cm with 24 capacitors.
Date: November 30, 1999
Creator: HAMMON,JUD; HARJES,HENRY C.; MOORE,WILLIAM B. S.; SMITH,DAVID L. & WILSON,J. MICHAEL
Partner: UNT Libraries Government Documents Department

PVUSA experience with power conversion for grid-connected photovoltaic systems

Description: The Photovoltaics for Utility Scale Application (PVUSA) project was established to demonstrate photovoltaic (PV) systems in grid-connected utility applications. One of PVUSA`s key objectives is to evaluate the performance, reliability, and cost of the PV balance of system (BOS). Power conditioning units (PCUs) are the interface between the dc PV arrays and the ac utility lines, and have proved to be the most critical element in grid-connected PV systems. There are five different models of PCUs at PVUSA`s Davis and Kerman sites. This report describes the design, testing, performance characteristics, and maintenance history of each of these PCUs. PVUSA required PCUs in the power range 25 kW to 500 kW which could operate automatically and reliably under changing conditions of sunlight and changing conditions on the utility grid. Although a number of manufacturers can provide PCUs in this power range, none of these PCUs have been produced in sufficient quantity to allow refinement of a particular model into the highly reliable unit needed for long-term, unattended operation. Factory tests were useful but limited by the inability to test under full power and changing power conditions. The inability to completely test PCUs at the factory resulted in difficulty during startup, field testing, and subsequent operation. PVUSA has made significant progress in understanding the requirements for PCUs in grid-connected PV applications and improving field performance. This record of PVUSA`s experience with a variety of PCUs is intended to help utilities and their suppliers identify and retain the good performance characteristics of PCUs, and to make improvements where necessary to meet the needs of utilities.
Date: November 1, 1995
Creator: Stolte, W.
Partner: UNT Libraries Government Documents Department

An Investigation to Resolve the Interaction Between Fuel Cell, Power Conditioning System and Application Loads

Description: Solid-Oxide Fuel Cell (SOFC) stacks respond quickly to changes in load and exhibit high part- and full-load efficiencies due to its rapid electrochemistry. However, this is not true for the thermal, mechanical, and chemical balance-of-plant subsystem (BOPS), where load-following time constants are, typically, several orders of magnitude higher. This dichotomy diminishes the reliability and performance of the electrode with increasing demand of load. Because these unwanted phenomena are not well understood, the manufacturers of SOFC use conservative schemes (such as, delayed load-following to compensate for slow BOPS response or expensive inductor filtering) to control stack responses to load variations. This limits the applicability of SOFC systems for load-varying stationary and transportation applications from a cost standpoint. Thus, a need exists for the synthesis of component- and system-level models of SOFC power-conditioning systems and the development of methodologies for investigating the system-interaction issues (which reduce the lifetime and efficiency of a SOFC) and optimizing the responses of each subsystem, leading to optimal designs of power-conditioning electronics and optimal control strategies, which mitigate the electrical-feedback effects. Equally important are ''multiresolution'' finite-element modeling and simulation studies, which can predict the impact of changes in system-level variables (e.g., current ripple and load-transients) on the local current densities, voltages, and temperature (these parameters are very difficult or cumbersome, if not impossible to obtain) within a SOFC cell. Towards that end, for phase I of this project, sponsored by the U.S. DOE (NETL), we investigate the interactions among fuel cell, power-conditioning system, and application loads and their effects on SOFC reliability (durability) and performance. A number of methodologies have been used in Phase I to develop the steady-state and transient nonlinear models of the SOFC stack subsystem (SOFCSS), the power-electronics subsystem (PES), and the BOPS. Such an approach leads to robust and comprehensive electrical, electrochemical, thermodynamic, ...
Date: November 3, 2003
Creator: Mazumder, Sudip K.; McKintyre, Chuck; Herbison, Dan; Nelson, Doug; Haynes, Comas; Spakovsky, Michael von et al.
Partner: UNT Libraries Government Documents Department