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Studies have been taken into the breakdown voltage jitter of corona-stabilized switch at high repetition rate up to several kHz. It is thought that the gas recovery affect the jitter of breakdown voltage directly at high repetition rate, because the gas switch will breakdown at a low voltage if the gas cannot fully recover. The breakdown voltage jitter is called voltage jitter in the following paper. However, based on the experimental results, the voltage jitter still exists at low repetition rate, even at single-shot mode. This is not explained by the previous studies. In this paper, voltage jitter below 100 Hz of a corona-stabilized switch is investigated experimentally. A corona-stabilized switch is introduced, using a cylindrical electrode as the cathode and a plane electrode as the anode. The gas used between the electrodes is SF6. A negative pulse with a maximum width of 30~\mu \texts is used to charge this switch. The tested factors include gas pressure, gap space, repetition rate, and switch geometry. Experimental results show that voltage jitter is mainly affected by the gas pressure and switch geometry. It is seen that voltage jitter decreases as gas pressure increases and a suitable cathode geometry presents a low voltage jitter. Critical volume is a region close to the highly stressed electrode, where the presence of an electron will lead to an electron avalanche which attains a critical size and hence leads to a stabilizing corona. Critical volume is introduced to explain the experimental results. It is found that less voltage jitter can be achieved with a smaller and more concentrated critical volume, as well as efficient corona stabilization. The results indicate that voltage jitter may be reduced by optimize the critical volume at low repetition rate. [ABSTRACT FROM PUBLISHER]

This paper investigates the issues of oxygen accumulation and variation in the high-resistance state of HfO2-based resistive random access memory (RRAM), with improvement attained by inserting a thin oxygen-vacancy-rich layer of indium-tin-oxide (ITO) film. By acting as the oxygen ion reservoir, this ITO thin film on the TiN electrode can further stabilize resistance switching (RS) characteristics. In terms of reliability, ac endurance, and retention tests confirm stable RS characteristics for the Pt/HfO2/ITO/TiN device. Finally, a conducting model was proposed to explain the influence of the ITO thin layer and clarify the physical mechanism of electrical improvements. [ABSTRACT FROM AUTHOR]

This paper proposes a vector control strategy for independent control of two permanent-magnet synchronous motors (PMSMs) using a single four-leg inverter (4LI). An expanded two-arm modulation to obtain a balanced three-phase output voltage is described. This paper also proposes a method to compensate for the fluctuations in the neutral point voltage of two split capacitors in the dc link. The experimental results show that independent speed and position control of two PMSMs can be achieved using a single 4LI with the proposed vector control method. [ABSTRACT FROM AUTHOR]

On transmission lines where switching surges are not mitigated with closing resistors and/or surge arresters, high-speed reclosing on a line with trapped charge will produce high overvoltages that have been measured above 3 p.u. Careful simulations of these switching events using available electromagnetic transient (EMT) programs consistently produce significantly higher voltages than the measurements. This indicates a phenomenon present on the line that acts to reduce the switching surge magnitudes but is not typically modeled. This paper aims to identify the required simulation practices in reproducing the field measured overvoltages in EMT simulations and investigates the sensitivity of results to modeling approaches and electrical parameters. Field measurements from a switching surge test of a 230-kV line without surge mitigation have been used for model comparisons. Variations in frequency-dependent line modeling, ground resistivity, skin effect, shunt conductance, parallel lines, and source-side detail have been tested in an unsuccessful attempt to decrease the difference between the field measurements and the higher simulation overvoltages. It is demonstrated that even though the pattern of the transient voltage waveforms can be reproduced very well using frequency-dependent line models, the magnitude of the maximum overvoltage is significantly overestimated unless the effect of corona is considered. Two types of corona models are tested, and both demonstrate that corona is the primary factor that allows the simulations to correctly reproduce high peak overvoltage measurements. [ABSTRACT FROM AUTHOR]

This paper proposes a variable off-time control method for a single-phase microinverter operating in the discontinuous conduction mode (DCM) for efficiency improvement. First, the fixed off-time control method is analyzed. The concept is to fix the off-time of the active switch throughout a line cycle for all output powers and scale the on-time of the active switch to shape a sinusoidal output current. Then, based on the fixed off-time control method, a variable off-time control method is proposed to modulate the preset fixed off-time in order to decrease the switching frequency during ac line zero-crossings and light load conditions. Compared with existed fixed-frequency DCM control or boundary conduction mode control, the variable off-time control is more flexible to optimize the efficiency under different load conditions as the switching frequency range can be automatically adjusted according to the output power. The switching frequency is high at heavy loads to limit the maximum peak current and is low at light loads to increase the light load efficiency. In addition, a predictive on-time method is adopted to simplify inverter control and reduce hardware costs. The parameter design principle is detailed in this paper. A 300 W prototype is built to verify the performance of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents the work carried out by the IEEE Working Grou[ on field-measured overvoltages and their analysis for validating power system component models to be used in switching transients studies. The work uses measurement data obtained from field tests performed by Bonneville Power Administration in June 1995 where switching overvoltages were measured on one of its 230 kV lines. This paper includes a description of the switching tests and the main results derived from field measurements. Details of the switching procedures that were followed to calibrate component models used to match field-recorded waveforms can be found in the Part II paper. [ABSTRACT FROM AUTHOR]

Bipolar junction transistors (BJTs) have been widely studied and used in nanosecond high-voltage pulse generators due to the advantages of fast switching speed and high repetitive frequency. Usually the Marx-type circuit is used to raise the peak value of output pulses. In this paper, a traditional BJT-Marx circuit using charging resistors is analyzed theoretically and experimentally. Based on the results, the structure of a circuit is changed to decrease the isolation voltage across the resistors, and diodes are used to replace charging resistors to block capacitors discharging to resistors. Experimental results showed that the three Marx generators proposed in this paper output pulses with higher voltage amplitude, and the last improved circuit outputs pulses with faster fall times at a higher efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a single-inductor dual-output (SIDO) dc–dc converter is proposed. The significant feature of the proposed converter is feeding a constant power load in low-voltage side (LVS) port, where even feeding a variable load at LVS does not have any cross regulation to high-voltage side port with the desired approximation. Magnificently, both merits are obtained in open-loop manner, which is an outstanding characteristic in comparison with that of the existed converters. In this paper, soft commutation and soft switching of switches and diodes are investigated along with the aforementioned main novelty. Moreover, detailed theoretical analyses of the proposed SIDO dc–dc converter in continuous conduction mode are presented besides the comparisons with some other structures. Finally, theoretical analyses are verified through a 1500 W experimental prototype results. [ABSTRACT FROM AUTHOR]

Explosive current opening switches (EOSs) operate based on the principle of the conductors mechanical destruction of the inductive energy storage system by detonation products of the high explosive charge. The EOSs are used for current pulse sharpening of the magnetocumulative generators (MCG). These explosive single-acting devices constructively match each other; both operate in the physical limit and provide maximum specific characteristics. This paper describes several basic schemes of the EOS constructions that were experimentally checked in different laboratories of the world. The investigation results on the flat and cylindrical models and also full-scale experiments on the current pulses sharpening of the helical and disc MCG are presented. [ABSTRACT FROM AUTHOR]

Enhancement of dc bus voltage utilization for a five-level inverter with single dc source and capacitor-fed H-bridge (CHB) units is investigated in this paper. A carrier-based modulation technique is used for boosting the dc bus utilization, which is established by providing detailed mathematical analysis. The five-level inverter used here is realized by cascading a CHB unit to each phase of a three-level neutral point clamped inverter. The increase in dc bus voltage utilization owes to the pole voltage redundancies offered by CHB units. The floating capacitors of H-bridge units are balanced within a quarter fundamental cycle using the switching state redundancies of pole voltage levels. The aforementioned modulation technique allows the inverter to enhance the dc bus utilization from 0.577 $\text{V}_{\text{dc}}$ to 0.63 $\text{V}_{\text{dc}}$ under unity power factor. This enhancement is obtained in the linear modulation range without increasing the dc bus voltage, and thus, the inverter can operate without the presence of low-order harmonics in its phase voltages. The strength of this paper lies in its detailed mathematical analysis for finding out the limiting modulation index and power factor condition in the light of floating capacitor voltage balancing issue. Simulation as well as experimental verification of the modulation scheme is carried out on an induction motor drive under various operating conditions. It is shown that this carrier-based modulation technique is suitable for any single source inverter topology with one CHB unit per phase. [ABSTRACT FROM AUTHOR]

Multioutput converters with single input source are currently studied as an alternative to conventional dc–dc topologies in order to improve power density in low-power multiload applications. This paper reviews three different ways in which a boost topology can be customized to supply multiple outputs. The first way uses a charge-sharing approach using individual switches to distribute inductor energy to different capacitors. The second method of creating a multiport converter (MPC) combines two converters with similar front end to generate two outputs using only one controlled switch. Using this method, a boost converter can be combined with single–ended primary–inductor converter (SEPIC), Cuk, and current source converter topologies. The third method uses time multiplexing of switches to produce two regulated ports and is referred to as switched-boost action. This method uses relatively less number of switches and allows regulation and control of all the outputs. Practical utility of switched-boost action based MPC is reported in this paper. This switched-boost MPC is applied to a renewable power converter system to interface a solar panel, a battery, and home loads to produce a 12-V and a 48-V bus. The 12-V bus is interfaced to battery and capable of optimally charging the battery in constant current–constant voltage (CC-CV) mode. The converter is demonstrated to operate with solar panel as it supplies a 12-V battery and a 48-V load bus. When the solar power is not available, the converter automatically goes into a mode in which the 12-V battery supplies the loads on the 48-V bus. [ABSTRACT FROM AUTHOR]

In this paper, a high-voltage unipolar pulse power generator is introduced for electroporation applications. Operating principle of the proposed structure is based on the buck–boost (BB) converter. The generator is comprised of parallel modules connected to the converter through an SCR and is supplied by a low-voltage dc source. Each module consists of an insulated gate bipolar transistor (IGBT), two diodes, and a capacitor. In fact, the proposed topology is a combination of the Marx generator and BB (MG-BB) converter. In comparison with other modular MG-BB structures, the proposed topology achieves interesting advantages including simpler structure, reduction of IGBTs voltage rating, and reducing number of components (inductors and switches). In order to clarify the features of the proposed structure, it has been compared with other unipolar MGs considering different aspects including the number of circuit components, number of required input supplies, amplitude of the output pulse, and the maximum voltage across switches and diodes. To validate the effectiveness of the structure, simulation and experimental results are presented. The results confirm that the proposed topology is capable of generating unipolar pulses with desirable amplitude and repetition frequency using a low-voltage dc supply. [ABSTRACT FROM AUTHOR]

This paper proposes a new fault-tolerant strategy to revamp performance of three-phase multilevel converters with a single faulty switch. The proposed fault-tolerant strategy is based on the application of a modified selective harmonic elimination (SHE) technique in conjunction with the fundamental phase-shift compensation method. The proposed fault-tolerant strategy makes the most use of the converter capacity in the faulty condition, generates balanced line voltages, and eliminates a wide range of lower order harmonics to limit the total harmonic distribution of the converter voltages in the faulty condition. In this paper, first, a brief background about cascaded H-bridge multilevel converters and SHE technique is provided. Then, the proposed fault-tolerant strategy and the modified SHE technique are presented. Finally, several experimental results are provided to validate the operation of the proposed strategy. [ABSTRACT FROM PUBLISHER]

Multilevel inverters have created a new wave of interest in industry and research. While the classical topologies have proved to be a viable alternative in a wide range of high-power medium-voltage applications, there has been an active interest in the evolution of newer topologies. Reduction in overall part count as compared to the classical topologies has been an important objective in the recently introduced topologies. In this paper, some of the recently proposed multilevel inverter topologies with reduced power switch count are reviewed and analyzed. The paper will serve as an introduction and an update to these topologies, both in terms of the qualitative and quantitative parameters. Also, it takes into account the challenges which arise when an attempt is made to reduce the device count. Based on a detailed comparison of these topologies as presented in this paper, appropriate multilevel solution can be arrived at for a given application. [ABSTRACT FROM AUTHOR]

This paper presents a novel control method for multimodule photovoltaic microinverter (MI). The proposed MI employs a two-stage topology with active-clamped current-fed push–pull converter cascaded with a full-bridge inverter. This system can operate in grid-connected mode to feed power to the grid with a programmable power factor. This system can also operate in line-interactive mode, i.e., share load power without feeding power to the grid. In the event of grid power failure, the MI can operate in a standalone mode to supply uninterruptible power to the load. This paper presents a multiloop control scheme with power programmable capability for achieving the above multiple functions. In addition, the proposed control scheme embedded a multimodule parallel capability that multiple MI modules can be paralleled to enlarge the capacity with autonomous control in all operation modes. Finally, three 250-W MI modules are adopted to demonstrate the effectiveness of the proposed control method in simulations as well as experiments. [ABSTRACT FROM PUBLISHER]

This paper proposes a new method to determine the overdrive (OD) to improve the response characteristics of displays based on the linearity in voltage domain. The proposed method estimates OD values by using a simple function between the slope of linearity and transition. The values of the function can be determined using only two measurements. The proposed work can be applied to both active-matrix liquid-crystal displays and active-matrix organic light-emitting diode (AMOLED) displays. OD artifacts were observable when OD deviation was over three gray levels. However, the average OD deviations were 1.47, 0.87, and 0.69 when the proposed method was applied to twisted nematic, in-plane switching, and fringe-field switching modes, respectively. The deviation in AMOLED displays was 0.45 gray levels. [ABSTRACT FROM AUTHOR]

This paper analyzes the combination in a cascaded H-bridge multilevel inverter (CHBI) based on transformers with the different turn ratios for increasing the voltage level and proposes the switching method for achieving the output voltage distribution among H-bridge cells (HBCs). The transformers used in this paper are connected to the output of the respective HBCs, and the secondary sides of all the transformers are connected in series for generating the final output voltage. Only one of the transformers, in particular, has a different turn ratio for increasing the output voltage level. In this paper, the possible turn ratio of the special transformer with a different turn ratio is discussed in detail, and a switching method based on the level-shifted switching method for the topology used in this paper is proposed. To verify the effectiveness of the proposed method, a three-phase 21-level CHBI is experimentally tested. [ABSTRACT FROM PUBLISHER]

In this paper, we model topology control through transmission switching as a recourse action in the day-ahead operation of power systems with large-scale renewable generation resources. We prove that transmission switching could only reduce the linear objective value of direct current optimal power flow when congestion exists. However, we also show, through a simple example, that unit commitment cost could be reduced by transmission switching even in the absence of congestion. To solve the stochastic unit commitment with topology control within reasonable computational time, we proposed a heuristic that first decomposes a practical system into zones and then solves the problem for each zone in parallel. The benefit of topology control recourse is demonstrated on a network representing the Central European System. We compare the costs of the network with different loading and renewable generation conditions. The cost reduction of the test system can reach 3.34% with heavy load and large-scale renewable generation while in a single zone the cost reduction can be above 7%. [ABSTRACT FROM PUBLISHER]

This paper proposes a current-fed single-phase inverter without constant intermediate DC link. It eliminates electrolytic capacitor from the DC-link and introduces an intermediate pulsating DC bus. The proposed topology is modular with three full-bridges making it scalable for high-power applications. New pulsating-DC-modulation for back-end pulsating DC-link inverter and secondary modulation (SM) for front-end DC-to-pulsating DC converter is proposed. Soft-switching and device voltage clamping of both primary side and secondary side devices of front-end current-fed full-bridge converter is realized. A rotating partial hybrid pulsewidth modulation has been introduced. One leg of inverter is commutated at a low switching frequency, while the other leg is operated at a high switching frequency for partial period of a line frequency cycle. Thus, switching losses of the back-end inverter are considerably reduced. Rotating mechanism is used to equalize the switching losses of four switches of the inverter. This paper presents detailed operation and analysis of the topology with a proposed modulation scheme. Simulation and experimental results validate the effectiveness and accuracy of the proposed modulation scheme as well as soft-switching and performance of the converter. [ABSTRACT FROM PUBLISHER]

This paper proposes a method for studying the reliability implications of line switching operations in power systems. Two case studies are conducted on RTS and IEEE 118-bus system to illustrate this method. This method is designed to explore previously overlooked areas in reliability evaluation of line switching operations. Line removal test is proposed to obtain simulation data of the system, and then with risk analysis and impact analysis, six reliability indices are used to evaluate reliability performance of each transmission line in the system. Instead of the traditionally used mean value, this method introduces variance into analysis. Weibull distribution is used to reconstruct distributions of reliability indices which provide worst case scenario comparisons in reliability evaluation. Eventually, with results obtained from the proposed reliability evaluation method, categorization for line switching operations is introduced to classify all transmission lines based on their reliability performance. The categories provide reliability implications of line switching operations and can be used for guidance in actual operations. [ABSTRACT FROM PUBLISHER]

Finite state model predictive control (MPC) has been recently applied to several converter topologies, as it can provide many advantages over other MPC techniques. The advantages of MPC include fast dynamics, multitarget control capability, and relatively easy implementation on digital control platforms. However, its inherent variable switching frequency and lower steady-state waveform quality with respect to standard control, which includes an appropriate modulation technique, represent a limitation to its applicability. Modulated model predictive control (M2 PC) combines all the advantages of MPC with the fixed switching frequency characteristic of pulse-width modulation algorithms. The work presented in this paper focuses on the indirect matrix converter (IMC), where the tight coupling between rectifier stage and inverter stage has to be taken into account in the M2PC design. This paper proposes an M2PC solution, suitable for IMC, with a switching pattern that emulates the desired waveform quality features of space vector modulation for matrix converters. The switching sequences of the rectifier stage and inverter stage are rearranged in order to always achieve zero-current switching on the rectifier stage, thus simplifying the current commutation strategy. [ABSTRACT FROM AUTHOR]

This paper shows that there is great potential for saving money when reconfiguring distribution systems at an optimal frequency. Studies are conducted on hourly, daily, weekly, monthly, and seasonal reconfiguration plans, based on the 8760 hourly loads of a year. Switches that actively participate in the reconfiguration process are first identified. These sectionalizers are substituted by smart (remotely controlled) switches. According to the results, two economic indices: total savings and return on investment are used to determine the optimal switching frequency. Numerical simulations are conducted on three distribution systems including one with 119 buses that is commonly used as a benchmark for reconfiguration of large-scale distribution systems. The results reveal that there exist large potential gains on frequent switching reconfiguration. Therefore, detailed studies must be carried out to determine the benefits of the dynamic reconfiguration for particular distribution systems. [ABSTRACT FROM AUTHOR]

The realm of hardware-in-the-loop simulation resorts to field-programmable gate arrays to achieve time steps below 1 \mu\s . Such low time steps are of importance for the aerospace and automotive industries, where power converters have their switching frequencies in the 10- to 200-kHz range. This paper proposes a network tearing technique that allows subsets of switches to be treated independently, alleviates embedded memory requirements, and reduces the computational burden. An iterative algorithm is used to determine the state of naturally commutated switches, thus offering a realistic model of the power converter, independently of its operation mode or topology. A Gauss-Jordan processing unit is implemented to solve interface voltages/currents from the torn circuit. Custom floating-point operators are used to ensure good accuracy, high-frequency operation, and low computational latency. A neutral-point-clamped converter case study is presented to demonstrate the effectiveness of the method. Simulation results are validated against a reference model at a 750-ns time step and a 30-kHz sine pulsewidth modulation switching frequency. [ABSTRACT FROM PUBLISHER]

The basic structure and work mechanism of laser-triggered vacuum switch (LTVS) are introduced briefly in this paper, and the processes of primary plasma production and expansion are analyzed as well. A series of experiments has been carried out with different gap voltages, laser wavelengths, laser energies, polarity configuration modes, switch structures, focal lengths, and laser waveforms. The switch structure is modified to improve the heavy-current capability of the switch, and the gap distance is increased to improve the voltage capacity. The special design of the trigger structure can reduce the dependence on the laser energy of the switch and the time delay. A new laser waveform of LTVS multiple wave crests could further decrease the laser energy, and it is the research basis of laser trigger miniaturization and its application in the LTVS. [ABSTRACT FROM PUBLISHER]

In this paper, a compact circuit topology is presented for pulsed power generation with a semiconductor opening switch (SOS). Such circuits require the generation of a fast forward current through the diode, followed by a reverse current that activates the recovery process. In general, magnetic switches are used to switch the diode current from forward to reverse. Therefore, adjustment of the output voltage of an SOS pulser is difficult. This paper introduces a circuit that allows an adjustable output voltage of the pulser. A solution is realized with a premagnetizing circuit on the primary winding of a pulse transformer (PT), so that a third winding is not needed. The primary capacitor voltage can now be varied while maintaining proper saturation of the PT. [ABSTRACT FROM PUBLISHER]

Thanks to the favorable advantage of low cost, integrated three-port dc–dc converters with reduced switches have attracted extensive attention. In order to provide more new topologies, this paper aims to propose a programmable topology derivation method, which effectively simplifies the cumbersome process of the conventional combination method. Instead of the manual connection and examination, the proposed alternative can quickly and rigorously derive multiple viable integrated three-port dc–dc topologies from a great number of possible connections with the aid of computer program. Besides, generalized analysis is also accomplished, with which performance characteristics of all derived converters are simultaneously obtained and then a comprehensive comparison can be easily conducted to select a preferred one for the practical application. Finally, an example-specific application with one input and two outputs is given, with topology selection, design, and experimental results demonstrated in detail. [ABSTRACT FROM AUTHOR]

A method for the seamless transition of three-phase inverters switched between grid-tied and stand-alone modes of operation is presented in this paper. In this method, only the inverter current and voltage sensors are utilized, and no control over the grid-side static transfer switch is needed. The presented method contains two strategies for grid-tied-to-stand-alone and stand-alone-to-grid-tied transitions. In the stand-alone-to-grid-tied transition strategy, a novel algorithm is presented for estimating the grid angle nearly instantaneously, which allows the three-phase inverter to respond very quickly if the grid and point-of-common-coupling voltages are out of phase. This fast response allows the inverter to effectively eliminate the transient overcurrent that would normally occur if it was connected to the grid without first being synchronized. The fast response also allows the inverter to return to normal operation very quickly after such an event. The strategy for the seamless transition from grid-tied to stand-alone mode is also presented. These strategies have been verified through experiments, and the results are presented in this paper. [ABSTRACT FROM PUBLISHER]

The current interrupting capability of a load break switch (LBS) depends on many design parameters, such as contact and nozzle geometry, contact movement, and gas flow. For developing more compact gas blow LBSs for air, it is necessary to find design recommendations where each parameter is addressed individually. In this paper, a current interruption test switch is built for this purpose. The interruption tests are conducted with a directly powered high-voltage circuit. The result shows the minimum gas flow required for current interruption for various basic nozzle geometries and at different contact positions. The study is particular relevant for the 24 kV/630 A class, and it is shown that 0.3 bar upstream pressure appears to be a threshold value for successful interruption. Some conclusions are also applicable for other medium-voltage ratings. An LBS should be designed so that at least one current zero crossing comes outside the nozzle when the switch is still blowing with full strength. [ABSTRACT FROM PUBLISHER]

This paper presents single- to three-phase dc-link converters with a reduced number of controlled switches for either usual or reduced currents in switches of the rectifier. A suitable model and a control strategy, including a synchronization approach, are developed to obtain the maximum dc-link voltage utilization. Such a synchronization method, associated with the pulse-width-modulated generation signal, forces the input current to have the same phase angle as the input voltage. The main advantage of the proposed converters along with the synchronization method is the reduction of the zero-crossing distortion normally caused by the use of diodes. Simulated and experimental results are presented to confirm the validity of the theoretical expectations. [ABSTRACT FROM PUBLISHER]

In this paper, an improved direct torque control (DTC) technique of a two-level inverter-fed five-phase induction motor (FPIM) drive for low-speed operation is presented. The operation of the FPIM with distributed winding requires the elimination of third-harmonic voltage, which, if not taken care of, would generate distorted stator current. For this, the concept of virtual vectors (VVs) is utilized. Before selecting the VVs for the DTC operation, a theoretical analysis is carried out to find the effects of these VVs on the torque and flux response of the FPIM under different speed and loading conditions. It is found that the rotor speed plays a crucial role in the selection of VVs. A particular VV has different effects on the torque change as speed varies. This analysis helps in the selection of VVs, hysteresis torque bandwidth, flux bandwidth, and efficient formation of sectors. Furthermore, in this paper, the performance of the FPIM during low-speed operation is improved by avoiding the demagnetization of the stator flux. To achieve this, a new modified lookup table is proposed. Superiority of the proposed method over the reported approaches is illustrated by experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, a model predictive control (MPC) based on optimal switching sequences (OSSs) for a single-phase grid-connected full-bridge neutral-point-clampled (NPC) power converter is presented. The predictive control algorithm is formulated in terms of OSSs, which was originally proposed to govern three-phase power converters. In this paper, the OSS concept is extended to control single-phase power converters. The proposed MPC algorithm belongs to the continuous control set MPC and is able to provide fixed switching frequency while handling system constraints. The proposed algorithm has been experimentally tested in an NPC power converter prototype. Experimental results show the desired fixed switching behavior in the steady-state condition and the intrinsic fast dynamic provided by MPC during transients. Furthermore, the test outcomes demonstrate the robustness of the proposed controller under large system parameter deviations. [ABSTRACT FROM AUTHOR]

This paper proposes a new fault-tolerant strategy for the purpose of revamping the performance of three-phase multilevel (ML) converters with faulty switches. The proposed fault-tolerant strategy is based on an adaptation of the modified space vector modulation (SVM) technique to the fundamental phase-shift compensation method. The proposed fault-tolerant strategy generates balanced line-to-line voltages with increased voltage levels in the faulty condition. In this paper, first a brief background about cascaded H-bridge (CHB) ML converters and SVM technique is provided. Then the proposed fault-tolerant strategy and the modified SVM technique are presented. Finally, several experimental results are provided to validate operation of the proposed strategy. [ABSTRACT FROM AUTHOR]

Aimed at the problem that the auxiliary commutation circuit (ACC) of auxiliary resonant commutated pole (ARCP) inverters has a high loss in commutation processes, this paper presents a novel modulation strategy with shunt dead time based on a double ARCP (DARCP) inverter. In comparison with the original modulation strategy, this modulation strategy cannot only achieve soft switching for all switches, but also avoid the superposition of resonance current and load current at commutation moments in double ACCs (DACCs) and make the maximum current through DACCs approximately equal to load current in commutation processes. So, the circulating current loss in DACCs and the current stress of auxiliary switches can be effectively reduced. According to the equivalent circuits in different operation modes under the novel modulation strategy, this paper analyzes the operation principle, soft-switching implementation condition, and optimal parameter design procedure of the DARCP inverter. Finally, a 10-kW–16-kHz DARCP inverter prototype with insulated gate bipolar transistor-based switches is built. Experimental results are given to demonstrate the validity and features of the DARCP inverter under the novel modulation strategy. [ABSTRACT FROM AUTHOR]

Switched boost inverter (SBI) is a single-stage power converter derived from Inverse Watkins Johnson topology. Unlike the traditional buck-type voltage source inverter (VSI), the SBI can produce an ac output voltage that is either greater or less than the available dc input voltage. Also, the SBI exhibits better electromagnetic interference noise immunity when compared to the VSI, which enables compact design of the power converter. Another advantage of SBI is that it can supply both dc and ac loads simultaneously from a single dc input. These features make the SBI suitable for dc nanogrid applications. In this paper, the SBI is proposed as a power electronic interface in dc nanogrid. The structure and advantages of the proposed SBI-based nanogrid are discussed in detail. This paper also presents a dq synchronous-reference-frame-based controller for SBI, which regulates both dc and ac bus voltages of the nanogrid to their respective reference values under steady state as well as under dynamic load variation in the nanogrid. The control system of SBI has been experimentally validated using a 0.5-kW laboratory prototype of the SBI supplying both dc and ac loads simultaneously, and the relevant experimental results are given in this paper. The low cross regulation and the dynamic performance of the control system have also been verified experimentally for a 20% step change in either dc or ac load of SBI. These experimental results confirm the suitability of the SBI and its closed-loop control strategy for dc nanogrid applications. [ABSTRACT FROM AUTHOR]

Common-mode voltage (CMV) in voltage-source inverters (VSIs) has been well defined and is frequently referred to in the literature. While often referred to, there is no real consistency with respect to how the CMV properties of an individual modulation scheme are evaluated, lacking tools to assess the relative merits or disadvantages of a certain topology or modification of a control scheme. The way that it is analyzed is still mostly a matter of the different authors' foci. In this paper, we propose a metric for the analysis of the CMV, aiming to fill the aforementioned gap. Thereby, the CMV in VSIs is quantified by the number of possible levels and the step sizes between different levels, as well as the respective frequencies of occurrence. The first two are given by the number of levels and the number of phases of the inverter. Depending on the modulation (control) schemes, all possibly available levels or a few of these levels are present in the CMV. We illustrate the use of the tool by applying it to thoroughly study the CMV properties intrinsic to the topologies of multilevel multiphase single- as well as double-ended diode-clamped VSI drive systems. As part of this analysis, we uncover new relationships concerning the existence of zero CMV level. Furthermore, we exemplarily apply the developed tool to the assessment of the CMV properties of selected pulse width modulation (PWM) control schemes and translate the findings into an interpretation of the endangerment of a given drive to suffer damage from inverter-induced bearing currents. The theoretical findings are supported by measurements. This paper also reviews the literature on CMV in multilevel multiphase VSI systems. With the proposed metric in mind, the CMV being mostly discussed as an element of different foci becomes even clearer, confirming again the need for the development of such a tool. [ABSTRACT FROM AUTHOR]

A multilevel H-bridge StatCom inherently contains redundancy in the available switching states. This paper develops a variation on the typical model predictive control scheme which is able to exploit this redundancy to simultaneously balance the H-bridge capacitor voltages, provide excellent current reference tracking, and minimize converter switching losses. The scheme consists of a dead-beat current controller that has been integrated with heuristic models of the voltage balancing and switching loss characteristics. The integration of a pulsewidth modulation scheme is also described. Simulation and experimental results are presented that confirm the correct operation of the control and modulation strategies. Comparison with traditional control and modulation schemes is provided in terms of the key performance indicators associated with multilevel H-bridge StatComs. [ABSTRACT FROM AUTHOR]

Traditional control strategy for a power decoupling circuit typically involves a dedicate ripple power control loop, which makes it hard to achieve satisfied transient performance. Meanwhile, traditional single-phase ac–dc converters achieve active power decoupling function with extra power switches, which inevitably increased the cost of the system. In this paper, a controller based on automatic power decoupling concept is proposed for a dependent power decoupling circuit with no extra switches. Compared with the existing methods, the system controlled by the proposed controller has superior transient performance with simplified controller's structure. The controller parameter's design procedures will also be illustrated step by step with the help of the bode diagram. In comparison with traditional control methods, simulations and experiments verify the feasibility of the proposed control methods on the dependent power decoupling circuit. [ABSTRACT FROM AUTHOR]

A new approach to performance validation of finite control set model predictive control (FCS-MPC) regulated power electronics converters is presented in this paper: statistical model checking (SMC). SMC is an established method used in various sectors of industry to provide solutions to problems that are beyond the abilities of classical formal techniques. The method is simple for implementation and requires only an operational system model that can be simulated and checked against properties. The approach will be presented on a standard two-level voltage source converter regulated by the FCS-MPC algorithm. In UPPAAL SMC toolbox, the converter system and controller are modeled as a network of stochastic timed automata. To assess the quality of the model, an equivalent Simulink model is used as a benchmark model. Using the model created in UPPAAL SMC toolbox the performance of the FCS-MPC algorithm is verified. The control algorithm is also tested on an experimental setup. During the evaluation, no significant degradation of reference tracking was found during transients nor under model parameter uncertainty. [ABSTRACT FROM AUTHOR]

A fully digital driving circuit for thin-film transistor liquid crystal display can offer benefits, including less power consumption and a shortened design schedule. Using the pulsewidth signal to control the moment to stop the ramp voltage, the pixel voltage can be set accurately. In this paper, the possible issues of power consumption, device nonuniformity, and parasitic capacitance are well-studied to prove the feasibility and advantages of the digital driving method. It is prospectively expected to substitute for the conventional analog driving method in the future. [ABSTRACT FROM AUTHOR]

The switched shunting resistor circuit is a classical and practical passive equalization scheme that nevertheless suffers from the voltage imbalance after the charging process. It results from the discrepancy of the shunting resistor and the physical characteristics of supercapacitor (SC) cells. In this paper, the distributed voltage equalization control strategies with the proportional-integral (PI) observer for the switched shunting resistor circuit are analyzed and compared. First, the charging and equalizing system is modeled as the switched system and the system observability is proved. The decentralized control and consensus control are analyzed and their shortages are presented. Then, the leader–follower cooperative control is proposed to improve the charging time while keeping the equalization performance. Meanwhile, the PI observer is designed to estimate the internal capacitance voltage of an SC precisely to avoid the effect of equal series resistance. The control convergence is proved by using the Lyapunov stability and switched system theory. The experimental results show that the proposed method has much superiority and wide applicability than the existing methods for equalizing voltages of SCs. [ABSTRACT FROM AUTHOR]

In this paper, performances on two kinds of aggregated flyback microinverters are compared in aspect of harmonic resonances, which are controlled by current feedback control and peak current control. Based on the Norton models of flyback microinverters obtained by a small-signal modeling approach, potential harmonic resonances with the grid are analyzed. Following that, an impedance-based stability criterion is proposed, where the resonance frequency can be calculated and predicted based on the derived Norton models and the system admittance matrix of aggregated microinverters. After comprehensive analysis and comparisons, it is found that the peak-current-control-based flyback microinverters has better performance on damping the harmonic resonances than the current feedback controlled one. Simulations and experiments are carried out for verifying the effectiveness of the presented models and the correctness of the analysis results. [ABSTRACT FROM AUTHOR]

This paper presents a new systematic control and fail-safe design methodology for a four-corner closed-loop air suspension (CLAS) system. The proposed control algorithm consists of “system control” determining the target heights of the four corners of the vehicle body from driving conditions and from the driver's commands and “actuator control” achieving the target heights by controlling actuators. A sliding-mode control with phase-compensated feedback signal is applied as the main part of the system control. With the use of the sliding-mode control, the proposed system control can improve control accuracy and robustness against delays and disturbances as well as reduce the bounce oscillation of the vehicle body. This paper proposes a stepwise height control as the actuator control to overcome the limited power of the production CLAS system. The stepwise height control adjusts the front corners and the rear corners alternately until the four corners reach their corresponding target heights. A fail-safe algorithm (FA) is also proposed to provide the fault detection (FD), diagnosis, and management of the CLAS. In particular, a model-based FD method for the pressure sensor and the height sensors, which are critical components in the CLAS control system, has been proposed. A mathematical model of a CLAS system is developed for algorithm development and simulation. The proposed control algorithm and FA are verified by simulations and actual vehicle tests. [ABSTRACT FROM AUTHOR]

A hybrid pulsewidth modulation (PWM), combining the merits of both space-vector PWM (SVPWM) and selective harmonic elimination (SHE) PWM (SHEPWM), is proposed for three-level neutral-point-clamped (NPC) inverter-fed high-power adjustable-speed drives, which uses asynchronous SVPWM at low frequency and SHEPWM at high frequency. For SHEPWM, a novel formula is proposed to obtain the initial values of switching angles, leading to another valid solution that is different from the known ones in the literature. Furthermore, it is shown that, by eliminating the quarter-wave symmetry, unlimited groups of solutions to three-level SHEPWM can be obtained. The characteristics of the multiple solutions in terms of harmonic distribution, pulsewidth, and total harmonic distortion are investigated for the application of SHE in practical drives. Switching between SVPWM and SHEPWM is problematic if no appropriate measure is taken, particularly when the influence of the minimum pulsewidth (MPW) is considerable. A simple but effective method, taking into account the MPW, is proposed in this paper to address this problem. The multiple groups of solutions to SHE are simulated and experimentally verified on a low-voltage three-level NPC inverter prototype. Experimental results obtained from a low-voltage prototype and an industrial 6-kV/1250-kW three-level drive are presented to validate the smooth switching between SVPWM and SHEPWM. [ABSTRACT FROM PUBLISHER]

Recent advances in lithium-ion battery modeling suggest unequal but controlled and carefully timed charging of individual cells by reduce degradation. This paper compares anode-side film formation for a standard equalization scheme versus unequal charging through switches that are controlled by deterministic dynamic programming (DDP) and DDP-inspired heuristic algorithms. A static map for film growth rate is derived from a first-principles battery model adopted from the electrochemical engineering literature. Using this map, we consider two cells that are connected in parallel via relay switches. The key results are the following: 1) optimal unequal and delayed charging indeed reduces film buildup, and 2) a near-optimal state feedback controller can be designed from the DDP solution and film growth rate convexity properties. The simulation results indicate that the heuristic state feedback controller achieves near optimal performance relative to the DDP solution, with significant reduction in film growth compared to charging both cells equally, for several film growth models. Moreover, the algorithms achieve similar film reduction values on the full electrochemical model. These results correlate with the convexity properties of the film growth map. Hence, this paper demonstrates that unequal charging may indeed reduce film growth, given certain convexity properties exist, lending promise to the concept for improving battery pack life. [ABSTRACT FROM PUBLISHER]

Inductive power transfer (IPT) for battery charging applications has significant advantages over the traditional plug-in system. Since misalignment between the primary and secondary windings is inevitable, it is of significance to improve the misalignment tolerance of IPT systems with constant-current (CC) and constant-voltage (CV) outputs for battery charging. In this paper, the load-independent output characteristic of the hybrid topology and the function switching between CC and CV of the reconfigurable topology are analyzed. Besides, a hybrid and reconfigurable IPT system with 3-D misalignment tolerance for CC and CV outputs is proposed, simplifying or even canceling control schemes. Moreover, a novel parametric design method is given for the IPT system, which can suppress the fluctuation of the output voltage/current within a certain range of misalignment. In order to validate the performance of the proposed topology, a 1-kW prototype is built, and the corresponding experiments are carried out. In the CC/CV mode, the system can operate with the longitudinal misalignment to 50% when the load varies from 36 to 480 Ω, and the fluctuation of the output current/voltage is within 5%. Similarly, the misalignment in Y- and Z-axis is 12.5% and 33.3%, respectively. [ABSTRACT FROM AUTHOR]

In order to incorporate the advantage of the $V^{2}$ control scheme and the benefits of digital implementation, this paper proposes a digital $V^{2}$ control with hybrid capacitor current ramp compensation, which includes the estimated output capacitor current ramp and the external ramp. Since capacitor current responds to the load change immediately, the proposed method has faster transient response than either digital inductor current compensation or external ramp compensation. The proposed estimator does not require high sampling rate and avoids the current ramp distortion due to the parasitic resistance and inductance. The small-signal model is derived by describing function to understand the dynamic characteristics of the proposed control scheme. The model provides design criteria of the current feedback gain and the external ramp slope. The effectiveness of the proposed control architecture and the current ramp estimator is verified by simulation and experimental results. Compared with the benchmark, the proposed control has 70% reduction on settling time and 20% reduction on undershoot deviation. [ABSTRACT FROM AUTHOR]

This paper presents a new concept and approach for topology control and switching in distribution systems by extending the traditional circuit switching to laterals and single-phase loads. Voltage unbalance and other key performance indicators including voltage magnitudes, line loading, and energy losses are used to characterize and demonstrate the technical value of optimizing system topology on a per-phase basis in response to feeder conditions. The near-optimal per-phase topology control is defined as a series of hierarchical optimization problems. The proposed approach is applied to IEEE 13-bus and 123-bus test systems for demonstration, which included the impact of integrating electric vehicles (EVs) in the test circuit. It is concluded that the proposed approach can be effectively leveraged to improve voltage profiles with electric vehicles, the extent of which depends on the performance of the base case without EVs. [ABSTRACT FROM AUTHOR]

A high-efficiency multimode battery charger with an adaptive supply voltage (ASV) control scheme is presented in this paper. The proposed battery charger includes a charging circuit and a dc–dc buck converter. The charging circuit automatically switches among trickle current (TC), constant-current (CC), and constant-voltage (CV) modes corresponding to the battery voltage while the buck converter with ASV control generates an ASV to closely track the battery voltage, leading to significant reduction in the power loss of the charging circuit. To further enhance the efficiency of the battery charger, zero-current detection and nonswitching control schemes are employed to decrease the power consumption of the buck converter in TC and CV modes. The battery charger was implemented with a 0.35- μm CMOS 2P4M process. The experimental results are shown to verify the theoretical analysis of the proposed charger. The maximum efficiency of the overall system is 88.3%, and the maximum efficiency improvement between the proposed charger and the conventional linear charger with fixed supply voltage is up to 11.6%. [ABSTRACT FROM AUTHOR]