Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)

This paper proposes a method for the efficiency optimization of ultra-high-speed permanent-magnet machines. Analytical methods are applied for the modeling of the machine that is equipped with a diametrically magnetized rotor and a slotless stator. The outer dimensions of the machine are design constraints, and the internal dimensioning is optimized for minimum losses. The air friction losses are taken into account in addition to the usual iron losses, copper losses, and eddy current losses. Laminated silicon iron or laminated amorphous iron is used as the stator core material. The results show that air friction losses influence the optimum design considerably, leading to a small rotor diameter at high speeds. The loss minimization and the amorphous iron core make it possible to reduce the calculated losses by 63% as compared to a machine design not considering air friction losses. The resulting efficiency is 95% for a 100-W, 500 000-rpm machine excluding bearing losses.
Prior to the establishment of the European Economic Community (EEC) each member state had its own individual standards covering electrical and control engineering in hazardous areas. With the advent of the EEC with its remit that there had to be free trading between all member states, it was necessary to align the individual country or state standards and various committees were established to fulfil this requirement, one being Cenelec (Committee for Electrotechnical Standardisation). Such a standardisation concept had existed since 1904-the idea of an English electrical engineer Colonel REB Crompton. He arranged a meeting of the electrical manufacturers of all the major nations and this took place in 1904-at the St. Louis International Congress, and a “Corresponding Committee” was formed. After some international “correspondence” the International Electrotechnical Commission was established on June 26<sup>th</sup> 1906, after which each country went its own way until the advent of the EEC. Some 60 years later, it therefore appeared to be a logical choice to harmonise the emerging European standards with those of the IEC and, by doing so, create standards acceptable to the USA and Canada. In the dissertation which follows, only the relevant IEC document No's have been quoted-their equivalents in Cenelec, NEC are given in the bibliography
Practical realization of modern high current and high switching frequency converters (with strong skin and proximity effects) requires a good control on layout-dependent parasitic components and on the power losses (thermal management), in order to meet the goal of high efficiency and reliability. In this paper, the physical realization of a VRM rated at 1.3 V - 50 A and switching at 1.8 MHz is analyzed in detail and discussed. Three prototypes, with same layout but different PCB structures and SR MOSFETs, have been tested. Moreover, an accurate thermal model was developed and experimentally validated in order to predict the maximum temperature of critical components.
Technology development of a high-power large-area mesa rectifier diode is described. For achieving the high reverse blocking capability, a shallow gradient deep Ga/Al impurity diffusion profile has been used in conjunction with surface electric field control. A positively-bevelled Mo-Si alloyed edge-contoured structure passivated by a high dielectric strength rubber, helped in realising the 4.4 kV diode. The behaviour of the reverse voltage-current characteristics of the diode has been studied at room temperature (25/spl deg/C) and elevated temperature (150/spl deg/C). The leakage current was 10 /spl mu/A at 4.4 kV at 25/spl deg/C and increased to 50 mA (maximum) at 4 kV at 150/spl deg/C. The variation of leakage current with process stages has been monitored. Influence of high voltage surface passivation on leakage current has also been investigated.
This paper highlights the experimental development and demonstration of an ETO module based on planar GTO technology that is well-suited to be scaled for a multitude of current requirements, with continuous current ratings from 100 A, and voltages up to 4.5 kV. The ETO module has low on state voltage drop and good snubberless turn-off capability. Different from press-pack ETO design, the ETO module employs industry standard module design widely used in IGBT module. Moreover, the ETO module has forward biased safety operation area (FBSOA), so it can achieve di/dt control and short circuit protection capability.
Transients following faults in the network and/or the tripping of generating unit auxiliaries can excite oscillatory torques on the turbine-generator-rotor-shaft system. The oscillations can be damped or amplified with time. Damped oscillations affect the power quality and if the oscillations grow with time they may even lead to generating unit outages. Well designed excitation control system can contribute significantly in quickly bringing the generating unit to new stable state following a disturbance thus preventing possible unit outage (depending on the extent of disturbance). However since the events following disturbance are very quick such corrective action by excitation systems is possible when it is kept on "auto" and not on "manual". The excitation control if kept on "manual mode" due to reasons of maintenance or lack of operator confidence may be sufficient for steady state voltage control and reactive power control with operator intervention but is not helpful in bringing the generating unit to new stable state following a disturbance as unit operator take time in initiating actions. Thus the personnel responsible for the operation and maintenance of generating unit need to have a deeper appreciation of the turbine generator oscillatory behaviour with the excitation control system in "automatic mode" as compared to that when the system is kept in "manual Mode" of operation. Such a comparative analysis would be very beneficial for motivating the plant personnel to ensure "automatic mode" of operation thus making the generating unit more stable following disturbance and preventing possible outages. This paper (Part II) is a contribution in this direction in continuation to the results reported in our earlier paper [Kumar, R et al., 2004]. In this work, comprehensive dynamic model of synchronous generator system with automatic excitation control has been developed in software Matlab/Simulink. The oscillatory behaviour of the turbine generator has been investigated in time domain following 10% step reduction in infinite bus voltage causing "pole slipping" if the machine operates with fixed excitation input. The torques exerted on turbine generator rotor shaft sections, causing fatigue, due to pole slipping have been investigated using the rotor shaft - model developed in Matlab/Simulink. The positive influence of automatic excitation control system in quickly bringing the generating unit to new stable state following disturbance, thus, preventing the rotor shaft stress has been clearly established.
With temperature-independent light output and long usable lifetimes, Hg-free dielectric barrier discharge lamps (DBDLs) exhibit distinct advantages. Their electrical parameters - driving voltages up to some kV, predominant capacitive impedance and a power factor in the range of 0.3 differ considerably from those of well-known fluorescent lamps. Electronic ballasts for DBDLs have to cope with these properties while on the other hand a compromise between system performance and costs must be found. This paper gives an overview on existing concepts with their specific advantages and drawbacks. Furthermore, 110 W electronic ballast for the OSRAM PLANON Lamp is evaluated.
In electricity distribution system, engineers of the power industry and utilities for general distribution applications have commonly used oil-immersed transformers. Other insulation options of transformers such as cast resin transformer (CRT), and SF6 gas-insulated transformer have also been mainly employed by engineers for the purpose of meeting environmental consideration and fire risk protection requirement. However most engineers might like to see the availability of an alternative option to SF6 gas transformer. A 110 kV cast resin transformer, which is now commercially available, may be considered as an ideal option for application in a fire risk-free 110 kV substation in urban areas with dense population. This paper attempts to describe the design and development of the proto-type CRT in different key technical aspects. The solutions to technical barriers due to resin insulation v.s. voltage level limitations were based on technical research, operation experience and supported by comprehensive tests. The construction and the technical characteristics of the CRT are therefore described in brief details. The paper discusses the general design aspects namely winding structure, heat dissipation, insulation compound structure capability to withstand high impulse voltage and short-circuited forces.
This paper presents a dynamic boost converter as input stage for a high efficient double 120deg flattop modulation based three-phase inverter. The boost converter can be regulated with hysteresis control or predictive PWM. The objective of the input stage is to provide a dynamic and accurate current into a pulsating DC-link. The algorithms are verified with simulations and experiments using a prototype. Both results show that the designed input stage can provide the required dynamics and accuracy for the three-phase inverter operating with double 120deg flattop modulation.
A nonresonant electronic ballast based on one power switch and on one reactive element-one inductance-is described in this paper. The special current mode control implementation provides an intrinsic short circuit protection and a very simple control circuitry. Filament heating time, current during the heating period and the protection against broken tube can be easily implemented with the proposed circuitry. A greenhouse application with a 120 V DC bus power distribution is presented in this paper. A high power factor and the DC bus voltage are easily obtained (in this particular application) from a classical series-connected 12-pulse rectifier in combination with a transformer with two secondary windings (one in Wye connection and other one in Delta connection)
This paper describes the development of an invaluable power quality tool through the application of a 120 kVA three-phase programmable AC power source with an integrated arbitrary waveform generator. Implementation details are presented including experimental results that demonstrate the flexibility of the source/arbitrary waveform generator to simulate common power quality disturbances such as voltage sags, swells, outages, harmonics, unbalance, and capacitor switching transients. Example test bed environments are developed and discussed allowing for the comprehensive power quality testing of loads such as adjustable speed drive systems, line-operated motors, and power supplies. Remote programming and control of the arbitrary waveform generator, including the development of an instrument driver library database, through LabVIEW is also discussed.
IGBT-modules are the most frequently used semiconductors for power applications. The markets demand for higher power integration in one module is limited by the chip losses and the housings capability to dissipate this power. With the 3<sup>rd</sup> generation of 1200 V IGBT modules eupec presents a product line with up to 50% higher current density in the same housing. In addition to familiar housings a new standard, the EconoPACK+, is introduced. So far the manufacturers had to deal with a three dimensional trade off between ruggedness, switching losses and saturation losses. Combining two technologies Infineon Technologies (formerly Siemens Semiconductors (HL)) in cooperation with eupec Warstein has designed the IGBT<sup>3</sup> that incorporates the ruggedness of a chip with a planar cell design with the low saturation of a trench IGBT. A vertically optimized device structure lowers the saturation voltage again and what is more important, also reduces the dynamic losses. In connection with eupec's advanced packaging technology this leads to a higher power integration without a rise of system costs due to additional protection circuits. The performance of 3<sup>rd</sup> generation IGBT modules is discussed and a new product range introduced
A new 5th generation IGBT module with low turn-off energy has been developed. The module utilizes IGBT chips optimized for high frequency industrial power supplies in applications such as X-ray, MRI (magnetic resonance imaging), and induction heating. This technology is designed to provide a simplified cost effective alternative to parallel discrete MOSFETs in these applications.
A new 1200 V IGBT with a V/sub CE/(sat) of 1.9 V at 125/spl deg/C and 140 A/cm/sup 2/ has been developed using a trench gate PT (punch-through) structure and local life time control. Compared to state-of-the-art third generation planar devices, this device represents a 30% improvement of on-state losses at almost twice the current density. This paper describes the structure and characteristics of this new IGBT.
This paper describes the performance of 1200 V silicon (Si) trench IGBTs and silicon carbide (SiC) Schottky freewheeling diodes (FWD) optimized for motor drive applications. The power loss and related voltage and current stress on the Si trench IGBTs and SiC Schottky FWDs are evaluated using a half-bridge test circuit. The optimized trench IGBT exhibits a 30% reduction in the total power loss as compared to state-of-the-art planar Si IGBTs with comparable short-circuit safe operating areas (SCSOA). An additional 30% reduction in total power loss is achieved by replacing conventional Si P+W diodes with SIC Schottky FWDs, mainly due to a 20× reduction in the reverse recovery charge. Furthermore, the SiC Schottky FWD significantly reduces the voltage and current stress on the IGBTs because of a 6× reduction in the peak reverse recovery current as compared to Si P+IN FWDs. In this paper we present the optimal design for 1200 V Si trench IGBTs with good SCSOA and a p-n junction barrier controlled SiC Schottky FWD with a low forward voltage drop of 1.74 V at 150 A/cm<sup>2</sup> and excellent reverse blocking capability with a low leakage current of 350 μA/cm <sup>2</sup> at 1200 V
The design of power semiconductor chips has always involved a trade-off between switching speed, static losses, safe operating area and short-circuit withstanding capability. This paper presents an optimized structure for 1200 V IGBTs from the viewpoint of all-round performance. The new device is based on a novel wide cell pitch carrier stored trench bipolar transistor (CSTBT). Unlike conventional trench gate IGBTs, this structure simultaneously achieves both low on-state voltage and the rugged short-circuit capability desired for industrial applications.
A new 1400 A/1200 V MEGA POWER DUAL/spl trade/ IGBT module has been developed for high power industrial applications. The new module incorporates the latest advances in chip technology to produce a device with the rugged safe operating area and low losses required in high power industrial applications. The new power chip is based on an optimized wide cell pitch carrier stored trench bipolar transistor (CSTBT). The module features an optimized high current dual (half bridge) package with low parasitic inductance and integrated features designed to allow simplified assembly of high power inverters.
A novel high voltage rectifier, called the Trench Oxide PiN Schottky (TOPS) rectifier, is described in this paper. The TOPS rectifier is a synergistic combination of a Schottky rectifier and a P <sup>+</sup>iN diode, using a trench oxide structure to achieve high aspect ratio P+ regions, which permits a superior trade-off between forward voltage drop and switching characteristics, as compared with SSD (Static Shielding Diode), P<sup>-</sup>-i-N, and P<sup>+</sup>-i-N rectifiers, white maintaining an excellent blocking capability. A reverse leakage current of 100 nA was measured at 1200 V for a high current TOPS rectifier (die area=0.5 cm<sup>2</sup>), which is comparable to that in a P<sup>+</sup>IN diode. TOPS rectifiers with different Schottky/P<sup>+</sup> ratios, SSD, P<sup>-</sup>-i-N, and P <sup>+</sup>-i-N rectifiers were fabricated using punch-through (EPI) wafers. The reverse recovery characteristics of the TOPS rectifier has a much smaller peak reverse recovery current I<sub>RP</sub> than those in the SSD and P<sup>+</sup>-i-N rectifiers. The stored charge Q<sub>rr </sub> in the TOPS rectifier is smaller than that in the P<sup>-</sup>-i-N rectifier
Intelligent power modules (IPMs) in the 600V class have been successfully applied to a variety of industrial and consumer applications for upwards of ten years. Transfer mold manufacturing technology was adopted about eight years ago to reduce cost and simplify and miniaturize inverters. Continued improvements in the internal module construction with lead frame and heat spreader optimization along with significant improvements in IGBT chip technology with the adoption of the carrier stored trench bipolar transistor (CSTBTtrade) approach have resulted in a cost effective, reliable, and thermally efficient power module technology. Today's 600V DIP IPMs are capable of driving up to 3.7kW. This paper presents the advancement of the transfer mold packaging technology to a 1200V converter-inverter-brake (CIB) module rated from 10 to 25A at 1200V which is driven and protected by a new 1200V HVIC. The features of the new DIP CIB and the functionality of the 1200V HVIC are explained. The complete power stage for up to 3.7kW inverters including three-phase input rectifier, brake chopper, and three-phase inverter as well as an NTC thermistor for temperature sensing of the base plate has been "transfer molded' into one compact package with particular attention to the minimum strike and creep distances required by UL and IEC
This paper presents the superior characteristics of newly developed low loss and low noise 1200 V IGBT module for the first time. In order to realize low noise emission, it is necessary not only to improve the reverse recovery characteristics of FWD but also to reduce the low current turn-on dl/dt of IGBT. New IGBT chip with high turn-on dl/dt controllability and low turn-on power dissipation has been successfully developed by the reduction of the Miller capacitance by the optimization of the surface structure. A 1200 V-450 A IGBT module which is installed the new IGBT and an optimized FWD chips has been able to realize 30% reduction of the switching power dissipation compared with the conventional IGBT module under the conditions to have the same noise emission characteristics.
This paper describes a 230/13.8 kV substation nuisance tripping experience caused by rolled out current transformer (CT) connections to the main transformer differential relay. A metering and relaying one-line diagram is included to describe the substation protection scheme and to identify what was overlooked during the design and factory review process. Three-line diagrams that illustrate the change of current in the CT leads to the differential relay caused by the change of CT installation position are included. The transformer differential relay settings and associated sensitivity to the effect of roll out CT wiring are discussed. Recommendations to correct such a design problem are provided.
Magnitude time plot of disturbances overlaid on the ITIC curve.
Current trends during possible ferroresonant incidents.
Voltage trend during possible ferroresonant incidents.
Transformer saturation characteristic used in simulation. [3]
Overvoltages, for which ferroresonance was the suspected cause, were observed in the meter shop of an electric utility company, which was correlated with a broken conductor in a 13.8 kV overhead line. The shape of the distorted waveforms and the presence of many power-factor correction capacitors on the lightly loaded line led to the suspicion that this was the cause. A time-domain electromagnetic transient simulation was used to reproduce the waveforms, verifying that ferroresonance was indeed the cause of the overvoltages
The enhancement of condensation heat transfer is of practical importance in many industries such as HVAC, power, and aerospace. The present work is concerned with the electrohydrodynamic (EHD) enhancement of external condensation on single commercial enhanced tubes. Future phases of this work will include applying the technique to practical heat exchangers and developing a prototype EHD condenser. Single-tube experiments were performed on two types of enhanced tubes. The refrigerant was R-134a, with the EHD voltage in the range 0 to 25 kV, saturation temperature 10 to 40°C, and heat flux 10 to 40 kW/(m<sup>2</sup>K). The results indicated that the external heat transfer coefficient significantly increased under the effect of electrical field. The optimum heat transfer enhancement was approximately 3-fold for either tube, with respective EHD power consumption lower than 1% of the test section heat transfer rate
The dual 42 V-14 V automotive powernet provides an opportunity for a high volume application of power electronics. To meet the needs of this market, namely low cost on one and stringent temperature and size requirements on the other side, we propose a modular packaging concept. The basic module is engineered to have good thermal management and to use existing technology platforms that lend themselves to mass production. The salient feature of the module is integrated thermal busbar, a heat path common for both power semiconductors and passive components. In addition, this busbar provides electrical interconnection and mechanical support for the module, as well as a part of the inductor winding. A number of modules are then connected in parallel in order to achieve the desired power rating.
Thermal analysis for a 42 V/14 V DC/DC converter with integrated inductors is performed. An interleaved DC/DC converter system with 4-channels was chosen for the automotive converter topology with 42 V/14 V dual output voltages. Coupled inductors were designed and used for the 4-channel DC/DC converter. A 3-dimensional thermal model based on finite-element modeling (FEM) using IDEAS is presented and the thermal behavior of the DC/DC converter system is simulated and analyzed. The thermal model includes a printed circuit board, integrated inductors, a heat sink and switching devices (MOSFET). The analyzed thermal result can help to design a converter system under severe ambient temperature conditions.
Self-excitation of induction motors compensated by permanently-connected capacitors is investigated in this paper. Theoretical analyses of self-excitation phenomenon are carried out by using some simplified equivalent circuits, and a hybrid mathematical model in ABC/dq axes, respectively in steady-state, and transient-state. An unusual operating condition of water pumping stations is reported, in which water within the pipeline may drive the motor in the reverse direction at speeds higher than synchronous, when a supply interruption coincides with a check valve failure. In order to prevent the motor from dangerous overvoltages due to self-excitation, it is recommended to connect a simple static protection circuit consisting of a resistor in series with a thyristor switch between any two lines of the motor. Critical resistance boundaries which will lead to loss of excitation, and demagnetisation of the rotor core are determined separately as a function of operating speed. A suitable resistance value chosen in the safe design area constitutes a reliable protection mechanism against self-excitation
Silicon carbide (SiC) power semiconductor devices are capable of being operated at higher voltages, frequencies and temperatures than silicon power devices. These SiC device capabilities will provide the power electronics designer with new possibilities to produce compact designs. Presently the JFET is the only controlled turn off/on SiC device that is close to commercialization and available as restricted samples. However the JFET is a normally-on device that requires a negative gate voltage to turn off. In order to correctly design a gate driver one must understand the characteristics of the JFET. This paper presents a description of the JFET semiconductor structure, and the SiC JFET's static and dynamic characteristics from room temperature to 200 °C. A SiC JFET gate driver circuit is presented and its performance described. The proposed gate driver improves the switching performance of the JFET by operating the gate in avalanche during the off time.
The limits of the severity of flicker caused by voltage fluctuations is defined in Europe by the standard CENELEC EN 50160. Under normal operating conditions, flicker level will not exceed the long term severity P<sub>lt</sub>=1 during 95% of the time in one week. This threshold was originally established considering that a lamp with tungsten coiled coil filament of 60 W and 230 V that is gas-filled produces a flicker perceivable by 50% of the population when it is supplied with a voltage that verifies P<sub>lt</sub>=1. Other light sources like fluorescent lamps and discharge lamps with ballasts exhibit a different behavior under the same supply conditions. This means that the flicker meter should be different for each type of illumination technique ir order to provide accurate information about flicker phenomena. At the same time, lamp age also plays an important role in flicker generation. In this research work, a test system and a methodology able to measure the optical fluctuation produced by different types of lamps and ballast is presented. This experimental platform allows to obtain a correlation between voltage flicker levels and optical flicker perception. It can be considered the first step in the definition of new lamp models. This work also shows that age lamp has a significant correlation with flicker generation.
This paper proposes a fault-tolerant operation strategy of three-level neutral-point-clamped PWM inverters in high power, high performance, safety-critical applications. Likely faults are identified and fault-tolerant schemes based on the inherent redundancy of voltage vectors of neutral-point-clamped inverters are presented. Simulation verification is performed and shows good fault handling capability. A 150 kW neutral-point-clamped inverter is constructed for flywheel energy storage applications. Experimental testing of the fault-tolerant operation strategy is in progress.
This paper presents the development of a 15 kW, 1500 r/min integral motor, with the same outer dimensions as an equivalent standard induction motor, but with the possibility of operating with speed control and at a higher efficiency. To make a compact integral motor, a permanent magnet rotor is used, the coils of the line-filter and the coil of the DC-link have been integrated with the stator core, only a small DC-link capacitor is employed, and the motor is controlled without a shaft sensor. Temperature and efficiency measurements on the manufactured prototype machine are performed and the results are very promising
With fast switching semiconductor devices like the insulated gate bipolar transistors (IGBT) it is possible to build inverter based high voltage power supplies for electrostatic precipitators. Comparing conventional SCR (Silicon controlled rectifier) based technology the average corona power can be increased significantly to improve the precipitator efficiency. Additionally, during flashovers the fast current control of IGBT power inverters improves the precipitator performance due to fast voltage recovery resulting in further increasing of the peak and average precipitator voltage. In a new approach, the advantages of higher distances up to 400 mm between the discharge and collecting electrodes could be addressed by a voltage up to 150 kV applied to the precipitator. Due to the exact voltage control of the IGBT inverter a smooth DC voltage can be generated and therefore, the overvoltage capability of the system is much lower than it would have to be with a conventional thyristor based high voltage generation system. Thus, the IGBT inverter solution becomes more economical or less expensive to operate than the conventional supply. With the availability of the latest generation of integrated IGBT modules a very compact IGBT inverter has been developed to meet the design requirements by operating at a frequency up to 10 kHz. The new IGBT types have lower saturation voltages than the previous modules resulting in lower power losses. The HV-transformer has been designed with the required rating and stray inductance.
The integrated gate commutated thyristor (IGCT) has steadily gained importance on the market since its introduction in 1996. Low on-state voltages and fast switching transients offer minimal semiconductor losses and the highest silicon utilization in medium voltage applications. The low component count in the reliable press-pack and the high utilization of silicon enable the design of low cost, reliable, compact and explosion free converters. Today 4.5 kV, 5.5 kV, 6 kV and 6.5 kV IGCTs are available. IGCT based converters dominate in industrial medium voltage drives (MVDs) as well as railway interties and other energy management systems. Recent developments are setting new converter standards.
This paper introduces a high speed brushless field excitation (BFE) machine that offers high torque per ampere (A) per core length at low speed and weakened flux at high speed. Lower core losses at high speeds, are attained by reducing the field excitation. Safety and reliability are increased by weakening the field when a winding short-circuit fault occurs. For a high-speed motor the bridges that link the rotor punching segments together must be thickened for mechanical integrity; BFE can ensure sufficient rotor flux when needed. Projected efficiency map including losses of the excitation coils confirms the advantage of this technology.
A high-speed 1600 kW permanent-magnet generator is being developed. The generator is designed to run directly from a gas turbine without a gearbox. The 600 Hz generator frequency is rectified by means of 6-pulse diode bridges. Connection to 50 Hz (60 Hz) mains frequency in the case of decentralized power generation is achieved by means of a power electronic converter based on a special interlaced technique with two 300 kVA IGBT stacks paralleled by means of an interphase transformer. A 500 kW (600 kVA) TWIN converter module with interphase transformer has been designed, built and tested. Details concerning the practical design aspects and the system control are given
This paper presents four new step-up and step-down 18-pulse direct asymmetric autotransformer rectifiers. The converters are designed to operate with variable frequency power supplies (400-800Hz), while meeting tight harmonic, power factor and output voltage requirements. The analysis takes into consideration the total number of windings used to achieve the step-up and step-down voltage gain-which determines the autotransformer structure and performance-the relative size of the windings as well as the total KVA ratings, and the existence of secondary-side series windings-which impact the commutation process of the diode bridges. A complete modeling procedure of the autotransformers is additionally presented with closed form expressions for all winding currents. Experimental results obtained with laboratory prototypes are used to validate the correct operation and high-performance of the proposed autotransformer rectifier units, where the polygon and delta-polygon autotransformer rectifiers showed the best results.
A novel concept of asymmetrical nine-phase diode rectifiers with 18-pulse performance is extended to voltage step-up or -down rectifier circuits, in which each diode conduction interval in the main rectifier is 80° and one in the two auxiliary rectifiers is 20°. The asymmetrical nine-phase diode rectifier requires differential delta-connected autotransformers having a 31.7 % VA rating of the DC output power without voltage stepping-up or -down, although a conventional symmetrical one requires a 51.4 % rating. A theoretical analysis for the idealized circuit gives that the proposed rectifier can be applied to the dc output range of 80-125% by the use of less than 50 % rating transformers. Experimental results for distortionless and distorted AC power supplies showed that the proposed rectifier can produce the resulting line-currents with significantly reduced harmonics. It will be well suited to a front-end of inverter-based applications because of its simple, robust structure, and a smaller transformer VA rating and smaller transformer losses.
Alstom Drives and Controls, Ltd has developed under US Navy sponsorship a novel 19 MW PWM motor and drive for use in naval ship propulsion applications. The design requirements for this application placed stringent constraints on the size and acoustic signature of the motor and drive. When combined, these requirements create a very difficult electromagnetic compatibility (EMC) problem for the motor drive. This paper describes the drive requirements, EMC features designed into the drive as well as lessons learned from the component and factory testing and from the commissioning of this unique drive
Adopting square wave excitation to drive induction motors (IMs) can substantially reduce inverter switching losses. However, the low-order time harmonics inherent in the output voltage generates parasitic torques that degrade motor performance and reduce efficiency. In this paper, a novel harmonic elimination modulation technique with full voltage control is studied as an interesting and alternative means of operating small (<1 kW) IM drives efficiently. A fully verified harmonic elimination scheme, which removes the 5<sup>th</sup>, 7<sup>th</sup>, 11<sup>th</sup>, 13<sup>th</sup> and 17<sup>th</sup> time harmonics, was implemented and applied to an IGBT driven IM. The power losses incurred in the inverter and the IM as a result of the switching scheme have been determined.
This paper presents the analysis and design of a new configuration of a resonant inverter suitable for high pressure sodium (HPS) lamp ballast applications. The proposed inverter results from the parallel connection of five class D LCsCp resonant inverters. Since the load current is shared among five equal sections, the circuit is able to drive lamps over 1kW using low cost power MOSFETs and achieves better efficiency than single class D solutions due to the reduction of the conduction losses. The regulation is implemented at constant frequency, modifying the phase displacement of the output voltage of one inverter section with respect to the others.
Cascaded neutral point clamped (NPC) inverter is more suitable for high voltage, high power applications, but the power and voltage balances are crucial in practical uses. This paper proposes an effective SPWM control scheme for a cascaded NPC inverter in which a pulse rotation is fulfilled for all modulation indices. The module voltage and power, and series- capacitor voltage of each module are perfectly balanced, and each module has low switching frequency providing high pulse frequency of phase voltage. The proposed scheme is applied to the 1M VA 6000 V 17-level cascaded NPC inverter for an 800 kW 4160 V induction motor drive. The experimental results verify the proposed scheme.
We analyze the performance of the hard handoff algorithm used in the 1xEV-DO Rev. A systems. A theoretical approach is presented to calculate the slot error probability (SEP). The approach enables us to evaluate the effects of filtering, hysteresis as well as the system introduced delay of handoff execution. Unlike previous work the model used considers multiple base stations (BS) and accounts for correlation of shadow fading affecting different signal powers received from different BS's. The theoretical results are verified over ranges of parameters of practical interest using simulations which are also used to evaluate the packet error rate (PER) and the number of handoffs.
This paper discusses a voltage pulse generator for producing streamer corona plasma. The generator consists of three resonant charging circuits, a transmission line transformer (TLT), and a self-triggered spark-gap switch. Voltage pulses in the order of 100 kV, rise time of 20-50 ns, pulse duration of 100-200 ns, pulse repetition rate of 1-1000 pps, corona energy of 0.5-3.0 J/pulse, and the average corona power of 2.0 kW have been achieved with total energy conversion efficiency of 65-85%. Detailed discussions on elements of the system are presented in this paper
A new six-phase, 2.4 MVA, soft-switched, medium voltage drive system utilizing series stacked modules with low voltage devices has been developed. The drive system combines a new soft-switched DC-DC converter with resonant DC link inverter technology to deliver extremely low THD sinusoidal output, high power density and high efficiency. The series stacked configuration with the associated single-phase loading lead to unique power and control design challenges. Device selection, control of parasitic elements, sensing methods for converter control, custom magnetic component design and clamping techniques have lead to a substantial improvement in device voltage utilization. The DC-DC converter controls must regulate the intermediate DC bus voltage under single phase loading while balancing transformer excitation and maintaining zero voltage switching, among other tasks. Proper control of the RDCL inverter requires the selection and tuning of the appropriate modulator and understanding its affect on the power circuit ratings.
This paper deals with dynamic behavior of a 21-level (line-to-line) BTB system based on series connection of sixteen converter-cells under a single-line-to-ground (SLG) fault condition. When the SLG fault happens, an imbalance in the supply voltage brings an amount of negative-sequence current to the BTB system. The negative-sequence current should be mitigated because it would result in an increased supply current and a dc-capacitor voltage fluctuation. This paper proposes a new control method intended for reducing both negative-sequence current and dc-voltage fluctuation to acceptable levels. A laboratory system rated at 200 V and 20 kW confirms the validity of the control method. In addition, this paper addresses the issue of magnetic saturation in the 16 three-phase transformers
Silicon carbide (SiC) switching devices have been widely discussed in power electronics due to their desirable properties and are believed to set new standards in efficiency, switching behavior, and power density for state-of-the-art converter systems. In this paper the design, construction, and performance of a 3 kVA All-SiC Current Source Converter (CSC) also known as Current DC-Link Back-to-Back Converter (CLBBC), is presented. CSC topologies have been successfully used for many years for high power applications. However, for low power range converter systems they could not compete with Voltage Source Converter (VSC) topologies with capacitors in the DC-link, since the link inductor has always been a physically large and heavy component due to the comparatively low switching frequencies of conventional high blocking voltage silicon devices. New SiC switches such as the JFET, which are providing simultaneously high voltage blocking, low switching losses, and low on-state resistance, offer new possibilities and allow for implementing a high switching frequency CLBBC and thus reducing size and weight of the DC-link inductor. The prototype CLBBC has been designed specifically for latest generation 1200 V, 6 A SiC JFETs for a target switching frequency of 200 kHz.
A 21-level (line-to-line) self-commutated BTB (back-to-back) system based on series connection of sixteen converter-cells has attractive features as follows: i) Both active and reactive powers can be controlled independently even in transient states, ii) The BTB system produces almost sinusoidal voltage at the AC side without performing PWM (pulse-width-modulation) control, so that no harmonic filter is required, iii) The BTB system provides an active-power response as high as 3 ms. This work presents experimental verifications of the self-commutated BTB system for the purpose of achieving power flow control in transmission systems. Experimental results obtained by a 200-V 10-kW laboratory prototype confirm effectiveness and validity of both the proposed system configuration and control strategy developed in this paper.
The IECEx Scheme provides a structured system to achieve global acceptance for explosion protected equipment for hazardous locations. Scheme members declare that they will abolish national differences for product requirements in their countries during the coming years. The international scheme will greatly impact the free trade of explosion protected apparatus needed for the petrochemical and chemical industry if the scheme members recognize and accept harmonized worldwide IEC standards. The goal is to develop and maintain uniform product evaluation to protect users against products which are not in line with the required level of safety. The critical aspects are identified by a comparison of advantages and disadvantages of such a scheme. The experience with the European system of Notified Bodies and harmonized CENELEC standards is a goad basis for consideration during the phase of establishing the IECEx Scheme. The result of fast introduction of IEC standards can be visualized by specifying possible conflicts in the national regulations. The updated version for 2000 still includes the latest perspectives from QAS and PTB (regarding an overview of the scheme), from UL (regarding a US perspective) and from LCIE (regarding a European perspective), in addition to now also being expanded to address Russia and Ukraine, instead of Canada. Furthermore the author list is opened up to a greater number of experts concerning these issues. The intention is to get a better understanding about these markets which are now accessible after a long period of isolation
The IECEx Scheme provides a structured system to achieve global acceptance for explosion protected equipment for hazardous locations. Scheme members declare that they will abolish national differences for product requirements in their countries during the coming years. The international scheme will greatly impact the free trade of explosion protected apparatus needed for the petrochemical and chemical industry if the scheme members recognize and accept harmonized worldwide IEC standards. The goal is to develop and maintain uniform product evaluation to protect users against products which are not in line with the required level of safety. The critical aspects are identified by a comparison of advantages and disadvantages of such a scheme. The experience with the European system of Notified Bodies and harmonized CENELEC standards is a good basis for consideration during the phase of establishing the IECEx Scheme. The result of fast introduction of IEC standards can be visualized by specifying possible conflicts in the national regulations. The updated version for 2000 includes the latest perspectives from QAS and PTB (regarding an overview of the scheme), from UL (regarding a US Perspective) and from LCIE (regarding a European perspective), in addition to now also being expanded to address Russia and Ukraine, instead of Canada. Furthermore the author list is opened up to a greater number of experts concerning these issues. The intention is to get a better understanding about these markets which are now accessible after a long period of isolation
Developed the science and technology, the projector price is suitable price for many people. They enjoy the oversize image easily. Nevertheless, the image unable comes out when light source is burned, unless replace its light source. The trend of projector is to improve illumination and quality. Under such a requirement, a small size, high illumination, and high efficiency lamp was developed, which is the ultra-high performance (UHP) lamp. Currently, the ultra-high performance lamp plays an important role, and almost replaces the metal halide lamp. One important thing is that without suitable power, the Ultra-high performance lamp can not start, and can not work for long time. In Ultra-high performance lamp, it consumes the electrodes fast, enlarges the gap, extends the arc length, and whites or blacks the inner shell. As well, more invalid lights are due to the arc deviates the focus of reflector. In addition, the applied power strongly affects the tungsten-halide recycle, and affects the lifetime. It is very important, but very few papers report the compatibility between applied power and lamps. Therefore, this paper will discuss the driving requirements of ultra-high performance lamp. It is very wonderful for many drivers and lamps designers. Likewise, the related acknowledge such as structures, processes, methodologies, and others are mentioned in this paper.
Auxiliary power supplies for traction rolling stock are used to power the carriage service facilities and control systems that are essential to keep a train operational. The design of converters for such applications is quite challenging, since the traction environment requires high performance systems that can manage a range of harsh environmental and electrical requirements without compromising performance, reliability and robustness. This paper presents the controller design for a 20 kW traction auxiliary converter that boosts a nominal 110 V DC battery supply to a regulated 600 V DC bus, to supply an associated 3-phase AC output inverter. The converter is required to operate over a wide DC input voltage range, produce a regulated high voltage DC output voltage, operate from no load to full power over the full input voltage range, support full output load rejection, and meet all usual traction converter robustness and reliability requirements. A further challenge for the system was to achieve good dynamic response under both continuous and discontinuous conduction modes despite the converter's high boost ratio and low switching frequency. The final controller was implemented as a fully digital DSP based system with an inner PI current regulator and an outer PI voltage regulator. Second order design issues that were also considered included the effect of DC source resistance and PWM transport delay. Modelling analysis, simulation results and experimental results are presented to demonstrate the controller's success in meeting its performance objectives.
Top-cited authors
T.A. Lipo
  • University of Wisconsin–Madison
F. Blaabjerg
  • Aalborg University
Fang Peng
  • institute of atomic and molicular physics
Hamid Toliyat
  • Texas A&M University
Rik W. De Doncker
  • RWTH Aachen University