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It is difficult to design a standard gate driver for optimal switching control of a static induction thyristor (SI-Thy) because of its unique internal structure and the direct commutation switching characteristic between the gate and cathode terminals during the transient turn-on and turn-off switching phases. Therefore, it is important to develop a simple and effective gate driver for achieving optimal fast turn-on and stable switching operations in an SI-Thy under hard-switching conditions. To achieve faster turn-on switching time with shorter gate delay time, impedance matching between the SI-Thy and the turn-on driving circuit component in the gate driver can be realized with additional circuit modification through this paper. To ensure higher stabilities in the turn-off switching phase, forced commutation techniques and additional auxiliary circuits in the gate driver have been devised to suppress the latchup and to eliminate potential ringing possibility. We have demonstrated that our designed and tested gate driver for realizing optimal switching characteristics of an SI-Thy is effective, particularly in the gate driving circuits for various pulsed-power switching applications. [ABSTRACT FROM PUBLISHER]

This paper describes two new approaches for the determination of the direction of switched capacitor banks as well as an efficient technique for estimating the distance of switched capacitors from the monitoring location in distribution systems. At first, two new indices based on branch voltage and current changes immediately after the capacitor switching instant are proposed for determining the direction of switched capacitor banks. The wavelet transform is used to detect the exact instant of switching. Then, a new technique based on linear circuit theory is proposed to estimate the distance of the switched capacitor bank from the monitoring location using capacitor switching transient data. Simulation results show that the error of the estimated distance is acceptable. A combination of the approaches for direction finding and the technique for distance estimation provide a novel method for determining the location of switched capacitor banks in real distribution systems. The method is valid in all normal, back-to-back, and abnormal switching of wye- and delta-configured capacitor banks. Also, the size of the capacitor bank has no effect on method accuracy. The efficacy of the proposed method is validated by using the IEEE 13-bus and 34-bus distribution systems. [ABSTRACT FROM AUTHOR]

In this paper, an interleaved soft-switching dc-to-dc converter configuration is proposed. It consists of two parts: the primary side is a constant-frequency asymmetrical converter with active-clamp feature and the secondary side is a series-resonant tank circuit. The active-clamp circuit recycles the energy stored in the magnetizing inductance of transformer to allow main/auxiliary switches turn-ON at zero-voltage switching and clamps the voltage stress of the main switches. Series-resonant tank circuit employs the transformer leakage inductance and secondary resonant capacitance to achieve zero-current switching of the output diodes. The circuit features constant-frequency operation and soft switching for both the transistors and the diodes. Interleaving operation of this configuration combines the aforementioned benefits and small output capacitor. Theoretical analysis and computer simulation of the converter were given. An 80-KHz 500-W experimental circuit of the proposed converter was demonstrated. [ABSTRACT FROM PUBLISHER]

This paper proposes an interleaved flyback converter, which is remarked with zero-voltage-switched active switches and reduced reverse-recovery loss on the rectifying diodes. The converter is composed of two parallel-operated identical flyback converters and an auxiliary inductor shunted between the diodes. This converter can provide up to 500 W power with highest efficiency as high as 91%. In addition, burst-mode control is equipped to drive the converter at low load. Even at 50-W output, the efficiency is higher than 83%. [ABSTRACT FROM PUBLISHER]

One of the major drawbacks of high-ratio step-up transformers is the high value of their secondary-side capacitor. This value is reflected at the primary side, giving rise to a nondesirable one. There are some converters which include this capacitor in the topology and can cope with it, and even more, they need it. In particular, in high-voltage applications, we will find transformers with a large capacitance value since they use high-ratio step-up transformers. In this kind of applications, it is always interesting not to have inductors at the output filter, with single-capacitor filters being preferred instead. Thus, one of the simplest topologies is the parallel resonant converter (PRC) with a single-capacitor output filter. It can be controlled by the switching frequency and/or duty cycle, which makes zero voltage switching feasible in the power switches. In this paper, the PRC modeling and design and the experimental results are shown in a prototype delivering 3.5 kV and 260 W. [ABSTRACT FROM AUTHOR]

AC voltage and phase regulators based on tap changers implemented with silicon-controlled rectifiers and triacs are widely used due to their robustness. Tap changing is achieved under natural commutation of semiconductors during the zero crossing of current, so that the response time exceeds the half cycle of the mains. High-power transistors and gate turn-off thyristor switches make new and faster tap commutation techniques possible to achieve several tap changes in one half cycle. This paper analyzes and synthesizes a dual-tap chopping stabilizer with a compensating transformer, with a pulsewidth-modulation frequency of about 5 kHz and a new soft-switching technique achieved by two auxiliary small-power branches. Unlike other supercyclic ac soft-switching solutions, the new commutating method allows zero current turn-off, several times in a half cycle, for any sign combination of voltage and current, thus reducing the electrical stress in the switches and the electromagnetic emission. Zero-crossing current detection is not needed. A technical study and an evaluation of the power of the required components are done on the commutation techniques that extend the application field of tap changers to the reduction of the fast perturbations of the mains as flicker, voltage harmonics, voltage oscillations, etc. Experimental results with insulated-gate bipolar transistor switches are obtained in a 1 kVA prototype. [ABSTRACT FROM AUTHOR]

A bidirectional dc–dc converter (BDC) with a new CLLC-type resonant tank, which features zero-voltage switching (ZVS) for the input inverting choppers and zero-current switching (ZCS) for the output rectifier switches, regardless of the direction of the power flow, is proposed in this paper. Possessing the very optimal ZVS +ZCS soft-switching feature, this proposed converter will have a minimized switching loss if all of the main switches are implemented with metal–oxide–semiconductor field-effect transistors, and thereby, the proposed converter is fully soft switched and totally snubberless. The detail operation principles, as well as the design considerations, are presented. The methodologies to develop a unidirectional ZVS+ZCS dc–dc converter for the corresponding pulsewidth modulation and frequency modulation converters are proposed. The approach on how to construct a fully soft-switched BDC has also been proposed and analyzed. Finally, a topology extension is made, and another fully soft-switched BDC is derived. A prototype, which interfaces the 400–48-V dc buses for the uninterrupted power supply system with a power rating of 500 VA, was developed to verify the validity and applicability of this proposed converter. The highest applicable conversion efficiencies for the bidirectional operational modes are exceeding 96%. [ABSTRACT FROM PUBLISHER]

Due to the fast changes of the voltage and current generated by the operation of power-switching circuits that supply inductive loads, wideband transients can be induced at the ports of electronic equipment operating in the same environment. The level of collected transients is responsible for the degradation of system performance as well as its reliability. This paper describes a circuit model by which the transient waveforms at the equipment ports can be analyzed for real applications in the early design stages. A compact injection probe, whose properties derive from simulations performed on the circuit model and on the results of experimental measurements, has been designed and fabricated to characterize IC susceptibility to electrical transients. [ABSTRACT FROM AUTHOR]

In this paper, a family of zero-voltage-transition (ZVT) pulsewidth-modulated converters with synchronous rectifier (SR) is introduced. The SR decreases the conduction losses, while it increases the achieved soft switching range. In this family of converters, zero-voltage-switching (ZVS) condition is attained for the main and rectifier switches. Also, zero-current switching is achieved for the auxiliary switch. In addition, the applied ZVS technique can eliminate the reverse recovery losses of the rectifier switch body diode. The ZVT buck converter with SR is analyzed, and the presented experimental results confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper presents a new three-phase rectifier that allows the operation as rectifier or as inverter, with the use of three conventional switching cells. This reversion of power flow can be obtained simply by the inverting two reference currents. The system is analyzed as a connection of three independent lower order subsystems, controlled by sliding regime with decentralized switching scheme. The output voltage can be lower, equal, or greater than the peak of the input voltage. The operation stages, equations, control strategy, and design of the converter are presented. Finally, experimental results are shown for operation as inverter and as rectifier. [ABSTRACT FROM AUTHOR]

The switching frequency of power semiconductor devices in high-power medium voltage drives is limited due to high switching losses. These drives often comprise an LC output filter. The filter introduces a resonant circuit that may be excited, for instance, by fast control transients. One option to avoid such oscillations is to apply damping control methods, which on the other hand usually require switching frequencies well above the filter resonance. This paper presents a predictive stator current controller that avoids the excitation of the filter resonance, realizes active damping and enables fast current control while maintaining low switching frequency. Feasibility and good dynamic performance of the proposed control method is demonstrated by simulation results of a 2.4 kV induction motor drive and by experimental results obtained from a 55 kW prototype ac drive. [ABSTRACT FROM AUTHOR]

This paper proposes a combination of neural network and a bandless hysteresis controller, for a switched capacitor active power filter (SCAPF), to improve line power factor and to reduce Iine current harmonics. The proposed active power filter controller forces the supply current to be sinusoidal, in phase with line voltage, and has low current harmonics. Two main controls are proposed for it: neural network detection of harmonics and bandless digital hysteresis switching algorithm. A mathematical algorithm and a suitable learning rate determine the filter's optimal operation. A digital signal controller (TMS320F2812) verifies the proposed SCAPF, implementing the neural network and bandless hysteresis algorithms. A laboratory SCAPF system is built to test its feasibility. Simulation and experimental results are provided to verify performance of the proposed SCAPF system. [ABSTRACT FROM AUTHOR]

The presence of the new liberalized markets has increased the interest in power-quality (PQ) disturbances due to their economic effect. In particular, in the case of disturbances caused by a single event (such as a capacitor switching or voltage sag), the waveform assessment can be difficult due to the rapid variations in waveform spectral component characteristics; these difficulties require a suitable choice of signal-processing techniques for spectral analysis and, in particular, the resort to time-frequency representations. In this paper, the adaptive Prony method is proposed to calculate PQ indices based on a time-frequency analysis of waveforms. Numerical applications on a simulated transient due to capacitor switching, a measured voltage sag, and a test waveform are also presented and discussed in order to investigate the validity of the proposed method. [ABSTRACT FROM AUTHOR]

This paper introduces a new method for evaluating the status of medium-voltage (MV) switching devices by defining two hybrid parameters. The device condition hybrid parameter (DCHP) and the device importance hybrid parameter (DIHP) are defined by using weighing factors. Three different methods were applied for determining the DCHP, while the DIHP is determined by using the differential evolution algorithm. Boundary values for the DCHP are calculated on the basis of economic criterion regarding minimum costs. The proposed approach was primarily developed for applying modern MV switching devices maintenance, but can also be used in network planning and for proper choosing of MV switching devices. It is elucidated by an example. [ABSTRACT FROM AUTHOR]

This paper describes a 6.6-ky adjustable-speed motor drive for pumps and blowers without transformer. The power conversion system consists of a front-end diode rectifier, a live-level diode-clamped pulsewidth modulation (PWM) inverter with a voltage balancing circuit, and a hybrid active filer for harmonic- current mitigation of the diode rectifier. The control of the inverter is characterized by superimposing a third-harmonic zero-sequence voltage on each of the three-phase reference voltages to achieve the so-called overmodulation and reduce the switching stress of insulated gate bipolar transistors (IGBTs). A 200-V 5.5-kW down- scale model is designed, constructed, and tested with focus on the five-level PWM inverter and the voltage balancing circuit. Experimental results obtained from the 200-V downscale model verify the viability and effectiveness of the 6.6-ky adjustable-speed motor drive, showing that the four split dc capacitor voltages are well balanced in all the operating conditions and that the switching stress of the IGBTs is reduced at low modulation indexes. [ABSTRACT FROM AUTHOR]

This paper describes the development of a semiconductor based switch for use in pulsed power technology. Because of the more stable operating conditions, given by the semiconductor devices, this switch could be used to replace the up to now in pulsed power technology common used spark gaps. We defined a technical concept for a semiconductor based switch with a maximum voltage of 20 kV and a current capability in the order of 1 kA. This concept also should enable to generate pulses widths of a few μs. We found an IGBT with a maximum blocking voltage of 1700 V, a signal rise time of 100 ns, and a short circuit current rate of 650 A to be suited to realize our concept for the switch. Because of the defined maximum voltage of 20 kV it was necessary to use a series connection of the IGBTs. To ensure a synchronous switching of the in series connected devices, a trigger unit was built up which was inductively connected to the driver circuits of the single IGBTs. Single devices where tested and separated for the series connection. With the handicap of a given 155 mm circuit board we designed a complete switch, basing on industrial standards, with 15 IGBTs and a finally maximum blocking voltage of 18 kV, and a current capability of 500 A. The design of this circuit also included the development of a protecting circuit (active clamp) to protect the single devices of an over voltage damage during the switching, and also to avoid an inhomogeneous split up of the voltage to the different devices. [ABSTRACT FROM AUTHOR]

This paper presents a new method for accurately determining all possible steady-state operating points of a switch-mode contactless power transfer (CPT) system. The method is based on a stroboscopic mapping model and accurate calculation of its fixed points corresponding to circuit zero current switching (ZCS) conditions. Four steady-state operating points are identified for, e.g., inductor-capacitor-inductor (LCL)-type CPT system. Voltage and current waveforms and switching periods are determined. Parameter influences on ZCS periods are studied by bifurcation diagrams. Both PSpice simulation and experimental results have verified the proposed method. The results provide new opportunities for a practical CPT system to operate at different soft switching frequencies. The method is very useful for analyzing switch-mode resonant circuits and designing new power flow controllers. [ABSTRACT FROM AUTHOR]

The switching frequency of medium-voltage ac drives is limited to low values to restrain the dynamic losses of the power devices. This favors the use of synchronous optimal pulsewidth-modulation schemes that minimize the harmonic current. It is a drawback, though, that optimal algorithms do not have a means to extract the fundamental component of the load current. High- performance torque control is therefore difficult to obtain. This paper proposes a method to identify the instantaneous fundamental component of the stator currents. A novel observer is developed for this purpose. The approach enables fast torque control at very low switching frequency. Experimental results from a 30-kW induction motor drive are presented. [ABSTRACT FROM AUTHOR]

This paper proposes a methodology for developing integrated auxiliary soft-switching cells for power converter systems with two or more switching poles. The integrated cells obtained are a combination of cells from the same soft-switching technique or even of cells from different techniques, giving rise to hybrid cells. The resulting cells have fewer components, are lighter, and have a smaller volume than the conventional ones. Experimental results from a 1-kW power converter with two switching poles are presented to demonstrate the proposed methodology. [ABSTRACT FROM AUTHOR]

Active three-phase pulsewidth-modulated rectifiers are connected to the grid by an inductance or an LCL filter. Although an LCL filter is more effective since it more efficiently attenuates the switching harmonics, it causes stability problems. To enable a stable operation, either a damping resistor or an active damping (AD) algorithm has to be used. However, while a damping resistor causes additional losses, an AD algorithm usually requires extra sensors. To avoid these disadvantages, this paper shows simulation and experimental results of a simple ac voltage sensorless AD solution that is suitable for industrial applications. [ABSTRACT FROM AUTHOR]

The modeling and control of a three-phase three- switch buck-type rectifier system with integrated boost output stage (Voltage Range Extended 4-Switch Rectifier) is analyzed in this paper. A cascaded multiloop control structure is presented that has the following features: constant output voltage for a wide input voltage range and stepwise changes of load; sinusoidal input currents in phase with the mains voltages that also remain sinusoidal in case of unbalanced mains conditions; and active damping of the input filter resonance. For the control design, an equivalent dc-dc small-signal model of the converter is derived and verified by simulations and measurements. Based on this and on the identification of the critical operating point, the controllers for the inner dc current and outer voltage control loops are selected. The stability of the closed loop system is discussed and the robust operation of the system is verified by measurements on a 5-kW prototype. [ABSTRACT FROM AUTHOR]

This paper presents a new dimmer that does not amplify light flicker in incandescent lamps. The development of this new dimmer is motivated by the fact that the incandescent lamp is very sensitive to voltage fluctuation and the typical $R{-}C$-circuit dimmer for incandescent lamps amplifies the light flicker considerably. The proposed method utilizes a 16-b microcontroller to calculate the fluctuation voltage and determine the appropriate firing angle for a power switch device in the circuit of the dimmer. The mathematical model and simulation of the incandescent lamp with the proposed dimmer are also presented. By dynamically adjusting the firing angle to compensate for the voltage, the proposed dimmer can substantially diminish the light flicker. Furthermore, a series of experiments on this dimmer has been made to test its performance, and the results demonstrate a remarkable reduction in amplifying effect of light flicker. [ABSTRACT FROM AUTHOR]

Neural networks (NNs have proven to be useful in approximating nonlinear systems and in many applications, including motion control. Hitherto, NNs advocated in switched reluctance motor (SRM) control have a large number of neurons in the hidden layer. This has impeded their real-time implementation with DSPs, particularly at high rotational speeds, because of the large number of operations required by the NN controller within a sampling interval. One of the ideal applications of NNs in SRM control is in rotor position estimation using only current and/or voltage signals. Elimination of rotor position sensors is practically mandatory for high-volume, high-speed, and low-cost applications of SRMs, for example, in home appliances such as in vacuum cleaners. In this paper, through simulation and analysis, it is demonstrated that a minimal NN configuration is attainable to implement rotor position estimation in SRM drives. The NN is trained and implemented on an inexpensive DSP microcontroller. NN training data, current, and flux linkage are obtained directly from the system during its operation. Furthermore, the chosen method is implemented on a single-switch-converter-driven SRM with two phases. This configuration of the motor drive is chosen because it is believed that this is the lowest cost variable speed machine system available. Experimental verification of this motor drive system is provided to demonstrate the viability of the proposed approach for the development of low-cost motor drives. [ABSTRACT FROM AUTHOR]

In this paper, a CLL resonant tank fed by an asymmetrical pulsewidth-modulated (APWM) drive train is presented as an attractive option for low-power point-of-use power supplies used in telecom applications. This configuration can guarantee zero-voltage switching (ZVS) for an extended input voltage range of 35-75 V, while significantly reducing the associated conduction loss present in existing topologies. Proper resonant tank design will ensure efficient operation over the entire working range by maintaining ZVS for all line and load conditions, as well as minimizing the conduction loss by decreasing the circulating-current commensurate with load. Analysis of the converter topology is conducted, and a design procedure is presented. Experimental results from a 25-W 48-V/2.5-V proof-of-concept prototype are presented to validate the analysis and simulation results and to highlight the merits of the proposed topology. The proposed converter is shown to provide a 7%-14% efficiency improvement over a reference topology. [ABSTRACT FROM AUTHOR]

This paper presents the design of a dual Z-source inverter that can be used with either a single dc source or two isolated dc sources. Unlike traditional inverters, the integration of a properly designed Z-source network and semiconductor switches to the proposed dual inverter allows buck-boost power conversion to be performed over a wide modulation range, with three-level output waveforms generated. The connection of an additional transformer to the inverter ac output also allows all generic wye- or delta-connected loads with three-wire or four-wire configuration to be supplied by the inverter. Modulationwise, the dual inverter can be controlled using a carefully designed carrier-based pulsewidth-modulation (PWM) scheme that will always ensure balanced voltage boosting of the Z-source network while simultaneously achieving reduced common-mode switching. Because of the omission of dead-time delays in the dual-inverter PWM scheme, its switched common-mode voltage can be completely eliminated, unlike in traditional inverters, where narrow common- mode spikes are still generated. Under semiconductor failure conditions, the presented PWM schemes can easily be modified to allow the inverter to operate without interruption, and for cases where two isolated sources are used, zero common-mode voltage can still be ensured. These theoretical findings, together with the inverter practicality, have been confirmed in simulations both using PSIM with Matlab/Simulink coupler and experimentally using a laboratory-implemented inverter prototype. [ABSTRACT FROM AUTHOR]

This paper investigates low-frequency beat and harmonics in grid-connected three-level pulsewidth-modulated (PWM) voltage-source converters with low switching frequencies. The impact of switching frequencies and switching sequence, as well as mitigation techniques, are studied. Different from some recent results, the analysis confirms the advantages of selecting switching frequency, as an odd-triplen multiple of the grid operating frequency, for eliminating imbalance and undesirable even-order harmonics, which can negatively impact the dc-link neutral-point balance in a three-level converter. Tests and analysis show that low-frequency subharmonic beat can occur in a carrier-based PWM converter when the switching frequency is low and is an imperfect multiple of the grid frequency. Recognizing the beat as interaction of the switching sequence and switching frequency, mitigation techniques to reduce the beat and associated harmonics are investigated and verified through experiments. A simple displacement of switching frequency from the odd-triplen multiple of the grid frequency can effectively suppress the beat with an asynchronous PWM scheme. [ABSTRACT FROM AUTHOR]

A predictive torque and flux control algorithm for the synchronous reluctance machine is presented in this paper. The algorithm realizes a voltage space phasor preselection, followed by the computation of the switching instants for the optimum switching space phasor, with the advantages of inherently constant switching frequency and time equidistant implementation on a DSP-based system. The criteria on how to choose the appropriate voltage space phasor depend on the state of the machine and the deviations of torque and flux at the end of the cycle. In order to obtain an appropriate model of the machine, it has been developed on a d-q frame of coordinates attached to the rotor and takes into account the magnetic saturation in both d-q axes and the cross-saturation phenomenon between both axes. Therefore, high-performance torque control is achieved, and the torque ripple is reduced. Simulated and experimental results using a DSP/field-programmable-gate-array-based control and a commercially available machine show the validity of the proposed control scheme. [ABSTRACT FROM AUTHOR]

High-efficiency speakers significantly improve electrical to sound power conversion efficiency by reducing the power dissipation over the speaker coil. However, they require some equalization of the input signal. In this paper, a new driving technique based on a pulsewidth-modulation switching amplifier is presented. This exploits a double voltage/current feedback to obtain automatic equalization. Furthermore, the double feedback allows the output resonant filter to be included in the feedback path, compensating for its nonlinearity. Finally, the mixed feedback acts as intrinsic current limiter. Both theoretical analysis and simulations demonstrate that this system is feasible. The results were also confirmed by measurements using a prototype. [ABSTRACT FROM AUTHOR]

A novel switching-frequency control method for regulated one-switch boost rectifiers operating at the boundary of discontinuous and continuous conduction modes is presented in this paper. To obtain a source current with the least amount of low-order harmonics, the duty cycle within a switching period is proportional to the ratio of the instantaneous value of the source voltage to the output voltage. According to the voltage gain analysis, the output voltage can be regulated by adjusting the switching frequency. Small-signal modeling is performed to facilitate the design process. The proposed control scheme features advantages such as higher input power factor and higher regulated output voltage compared to the traditional discontinuous conduction control with a fixed switching frequency and a constant duty cycle. Any well-developed commercial pulsewidth-modulation control integrated circuit can be adopted with only a minor modification. Experimental results show good conformation with the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a compensation strategy for the unwanted disturbance voltage due to inverter nonlinearity. We employ an emerging learning technique called support vector regression (SVR). SVR constructs a motor dynamic voltage model by a linear combination of the current samples in real time. The model exhibits fast observer dynamics and robustness to observation noise. Then the disturbance voltage is estimated by subtracting the constructed voltage model from the current controller output. The proposed method compensates for all of the inverter nonlinearity factors at the same time. All the processes in estimating distortions are independent of the dead time and power device parameters. From the analysis of the effect on current measurement errors, we confirmed that the sampling error had little negative impact on the proposed estimation method. Experiments demonstrate the superiority of the proposed method in suppressing voltage distortions caused by inverter nonlinearity. [ABSTRACT FROM AUTHOR]

The concept of hybrid clamped is proposed in multilevel-inverter topologies, and a hybrid-clamped multilevel-inverter topology comprising active and passive clamping devices is presented in this paper. In this topology, the dc-link capacitor voltages can be balanced without additional circuitry or separated dc voltage sources, regardless of load characteristics. It can be used in real and reactive power conversion applications. The topology structure, operating principle, and self-voltage balancing ability are analyzed. In addition, the validity is confirmed by simulations and experiments based on a five-level inverter. Finally, the functions of different clamping devices are compared. [ABSTRACT FROM AUTHOR]

The zero-voltage transition (ZVT) pulsewidth- modulation (PWM) converters with resonant auxiliary circuit (RAC) are gathered and analyzed by means of a common topology derived in this paper. Its operation modes are identified and analyzed. Moreover, a similarity transformation is applied to the three-state-variable system in such a way that the whole system dynamics can be represented in a two-dimensional state space. With this representation, the soft-switching conditions are easily defined. In addition to the unified analysis of the ZVT PWM converters with RAC, a theoretical comparative analysis addresses the converter current and voltage stresses, as well as the time-delay intervals taken during the main-switch turn-on process. By means of this analysis, the main characteristics and constraints of the converters are identified. Moreover, a novel design methodology is presented. It is based on the soft-switching-condition abacus obtained from the analytical description of the common ZVT-RAC topology. Besides the soft-switching conditions, a set of performance parameters is also plotted into the soft-switching-condition abacus, making it a simple and useful tool for the proper design of a ZVT-RAC converter. An experimental efficiency comparison is also carried out among three ZVT-RAC boost converters. The experimental results have been obtained from ZVT PWM boost prototypes operating at 1 kW and 100 kHz. [ABSTRACT FROM AUTHOR]

A soft-commutating method and control scheme for an isolated boost full bridge converter is proposed in this paper to implement dual operation of the well-known soft-switching full bridge dc/dc buck converter for bidirectional high power applications. It provides a unique commutation logic to minimize a mismatch between current in the current-fed inductor and current in the leakage inductance of the transformer when commutation takes place, significantly reducing the power rating for a voltage clamping snubber and enabling use of a simple passive clamped snubber. To minimize the mismatch, the method and control scheme utilizes the resonant tank and freewheeling path in the existing full bridge inverter at the voltage-fed side to preset the current in the leakage inductance of the transformer in a resonant manner. Zero-voltage-switching is also achieved for all the switches at the voltage-fed side inverter in boost mode operation. The proposed soft-commutating method is verified through boost mode operation of a 3-kW bidirectional isolated full bridge dc/dc converter developed for fuel cell electric vehicle applications. The tested result verified the isolated boost converter can operate at an input voltage of 8.5–15 V and an output voltage of 250–420 V with a peak efficiency of 93% and an average efficiency of 88% at 55-kHz switching frequency with 72 °C automotive coolant. [ABSTRACT FROM AUTHOR]

This paper presents an active harmonic elimination method to eliminate any number of specific higher order harmonics of multilevel converters with equal or unequal dc voltages. First, resultant theory is applied to transcendental equations characterizing the harmonic content to eliminate low order harmonics and to determine switching angles for the fundamental frequency switching scheme and a unipolar switching scheme. Next, the residual higher order harmonics are computed and subtracted from the original voltage waveform to eliminate them. The simulation results show that the method can effectively eliminate the specific harmonics, and a low total harmonic distortion (THD) near sine wave is produced. An experimental 11-level H-bridge multilevel converter with a field programmable gate array controller is employed to implement the method. The experimental results show that the method does effectively eliminate any number of specific harmonics, and the output voltage waveform has low THD. [ABSTRACT FROM AUTHOR]

Many accelerators at Sandia National Laboratories utilize the Rimfire gas switch for high-voltage, high-power switching. In addition, there are many multichannel closing switches used in pulsed power applications. This paper presents a study of the multichanneling section of the Rimfire switch. The electrical effects of multichanneling and a method to force multichanneling are presented. In addition, an objective curve fitting method is utilized to deduce switch inductance from the measured data. [ABSTRACT FROM AUTHOR]

This paper presents a new sensorless vector control system for high-performance induction motor drives fed by a matrix converter with nonlinearity compensation. The nonlinear voltage distortion that is caused by commutation delay and ON-state voltage drop in the switching devices is corrected by a new matrix converter model. A reduced-order extended Luenberger observer is employed to bring better response in the whole speed operation range, and a method to select the observer gain is presented. Experimental results are shown to illustrate the performance of the proposed system. [ABSTRACT FROM AUTHOR]

This paper presents a novel control method to lower the harmonic components of the conventional voltage balancing control for the multilevel converters. The harmonic components in the voltage balancing control theory are analyzed in detail. A revised control method based on the line-line voltage redundancy of the three-phase inverter is proposed to lower the harmonic components of both the converter and inverter side. The proposed method can significantly reduce the harmonic components while keeping the switching frequency nearly the same. Simulation and experimental results are provided to show the validity of the theory. [ABSTRACT FROM AUTHOR]

This paper describes the construction and experimental tests of a 12-kV high-voltage high-action generator based on reverse-switching dynistor (RSD) assembly. The main RSD unit consists of seven 76-mm-diameter dynistor pieces connected in series with a blocking voltage of about 2.4 kV, a magnetic switch based on a 1K101 amorphous alloy core, the trigger system based on a saturable transformer, and a 16-mm RSD assembly; the trigger current could reach 2 kA in amplitude with 1-\mu\s duration under 10 kV. The working voltage rate of this RSD unit is about 8–12 kV. Experiment on a 2.2-mF capacitor test bed under 12 kV working voltage, the switch current amplitude reached 150 kA with 300-\mu\s duration; the transferred charge is about 26.5 C and the action is 2.94 \MA^2\s, respectively. [ABSTRACT FROM AUTHOR]

This paper describes the operation of a solid-state series stacked topology used as a serial and parallel switch in pulsed power applications. The proposed circuit, developed from the Marx generator concept, balances the voltage stress on each series stacked semiconductor, distributing the total voltage evenly. Experimental results from a 10 kV laboratory series stacked switch, using 1200 V semiconductors in a ten stages solid-state series stacked circuit, are reported and discussed, considering resistive, capacitive and inductive type loads for high and low duty factor voltage pulse operation. [ABSTRACT FROM AUTHOR]

Energy conversion enhancement of piezoelectric materials has been subject to intensive research over the last decade. Among the proposed solutions (for instance, single crystal), it has been shown that applying a simple and low-cost nonlinear treatment to the voltage output can significantly increase the conversion abilities of such materials. However, such an approach also adds significant electrical losses, dramatically reducing the available electric energy generated from the mechanical excitation. Such an observation is even more important when the energy in the system is limited, for example when the structure is submitted to a pulsed excitation. The purpose of this paper is to describe an efficient approach for reducing such losses, based on the transfer of the electrostatic energy when it starts to decrease. It is shown that such an approach allows increasing the converted energy by a gain up to a factor of 3, especially for weakly coupled electromechanical systems. [ABSTRACT FROM AUTHOR]