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This paper proposes a control method to balance capacitor voltages in a four-switch single-stage two-phase-switched-reluctance motor drive with integrated power factor correction during startup and at low speeds. Initial alignment process is incorporated for switched-reluctance machine before startup. However, the phase currents are unbalanced during that time. This will cause overvoltage on dc capacitors in split-ac configuration leadings to their failure. This problem also exists when the motor speed is very low, as observed in the startup process of compressors. Based on a unified model, an effective control method is proposed to eliminate the voltage difference between the capacitors. This method does not require any additional circuits or components. It also does not affect the performance during normal mode of operation. Experiments are performed to verify the feasibility of the control method. [ABSTRACT FROM PUBLISHER]

Soft-switching techniques have become very attractive in bidirectional grid-tie dc–ac converters utilizing high-frequency link transformers for galvanic isolation. This paper presents a new pulse-width modulation (PWM) switching technique for controlling a bidirectional isolated dc–ac–ac converter along with its soft-switching method. The proposed PWM technique has the ability to control the input dc current and to inject a sinusoidal three-phase current to the grid at unity power factor. In the first stage, an H-bridge converter is used to convert the dc voltage to a high-frequency square-wave single-phase voltage. In the second stage, a matrix converter is used to convert the high-frequency voltage waveform to conventional three-phase voltage synchronized with the grid. Therefore, a single-phase high-frequency transformer is used to link the H-bridge output voltage to the matrix converter input voltage. The proposed soft-switching technique is achieved by connecting shunt ceramic capacitors across all converter switches. The mathematical model and the circuit operation for soft-switching are presented along with the voltage controllable limits. The effectiveness of the proposed technique has been verified experimentally using a laboratory prototype. [ABSTRACT FROM PUBLISHER]

In order to increase the output voltage levels and reduce the isolated dc sources, a symmetrical hybrid nine-level inverter for high-speed motor drive applications is presented in this paper. Each phase of this inverter is composed of a five-level dc/dc converter cell and an H-bridge cell. The dc/dc converter is operated at high frequency with low-voltage devices and the H-bridge is operated at fundamental frequency with high-voltage devices. The three phases are connected to a common dc-link and each drives an isolated winding of an open-winding motor. The operating principles and modulation method are introduced. A detailed analysis of the average currents through the flying capacitor and neutral point of the dc-link is presented and a capacitor voltage balancing method based on phase-shifted pulse-width modulation is proposed. Simulation and experimental results are presented to demonstrate the feasibility of this topology and control method. [ABSTRACT FROM PUBLISHER]

Reliability stress testing of power semiconductors requires significant development effort for a test apparatus to provide the required functionality. This paper presents a modular test system (MTS) architecture that focuses on flexibility, reusability, and adaptability to future test requirements. Different types of tests for different devices in application circuit configuration can be implemented based on the same MTS concept. Vital parameters of the device under test can be acquired in situ during the running stress test. This enables the collection of drift data of these parameters. The control and data acquisition parts of the test system are clearly separated from the actual test circuit. With this physical separation, the same control part can be used for different types of tests. Experimental results of an already implemented test system are provided. [ABSTRACT FROM PUBLISHER]

Boost-derived hybrid converter (BDHC) is a single-stage converter that produces both dc and ac output voltages. The operation of BDHC under continuous conduction mode is satisfactory. However, the nonzero discontinuous conduction mode (NZ-DCM) and standalone ac operation restrict the stable operation of the converter. To mitigate these limitations, modified BDHC (MBDHC) is proposed in this paper. The main idea behind these changes is to redeem NZ-DCM by forced continuous conduction mode (FCM). The adverse effect of NZ-DCM in a BDHC is analyzed in terms of ac output voltage total harmonic distortion, and dc output voltage ripple. This analysis is further extended for MBDHC to highlight the benefits of FCM. Moreover, for hybrid loads, the efficiency of MBDHC is compared with its counterpart BDHC and cascaded boost inverter. [ABSTRACT FROM PUBLISHER]

This paper investigates the utilization of two different six-leg configurations of single-phase to three-phase converters. One of the topologies is transformerless and the other is transformer based. The studied converters allow feeding the load voltage with sinusoidal voltages with constant amplitude and frequency, and to operate with sinusoidal grid current with high power factor. The system model and pulse-width modulation techniques for one of the topologies are given. Control strategies for both topologies are provided. The studied topologies are compared with the conventional in terms of dc-link specification, voltages harmonic distortions, semiconductor losses, and other characteristics. Simulation and experimental results are provided to illustrate the operation of the systems. [ABSTRACT FROM PUBLISHER]

This paper presents an original modular plug-in-type assembly approach for a single-phase inverter. The main focus here is, indicatively, on the power range 1–20 kW, but the methodology can be transferred to higher power levels too. At the core of the inverter lies a power-dense double-sided-cooled half-bridge power switch architecture with integrated cooler, which is interconnected to filter elements, gate driver, and control circuitry by means of compact flat connectors. The integration exercise targets, on the one hand, the optimization of the power switch performance and reliability, as well as the reduction of circuit parasitic elements; on the other, the production of a system compatible with maintenance and repairing, featuring minimized impact of single component failure on the system maintenance and repair cost, and, thus, on its availability. Preliminary experimental tests demonstrate the nominal functionality of the inverter. [ABSTRACT FROM PUBLISHER]

A novel hybrid five-level voltage-source converter for high-efficiency applications is investigated in this paper. Compared with traditional multilevel converters, this hybrid multilevel converter generates desired staircase voltage levels with a reduced number of power devices and isolated drivers at higher voltage levels. It has redundant switching state combinations in hybrid multilevel converter, which makes it easy to balance flying capacitor voltages and realize fault-tolerant operation. A voltage-balancing control strategy based on switching state redundancies is presented for the hybrid multilevel converter to generate desired levels and also keep voltage balance of flying capacitors at the same time. The performance of the hybrid multilevel converter under various operating conditions is investigated in MATLAB/Simulink. The effectiveness of the proposed hybrid multilevel converter is validated by experiment results. [ABSTRACT FROM AUTHOR]

As a result of dead-time, device on-state voltage drop, dc bus voltage measurement error, etc., volt-second errors degrade precise control of torque and flux linkage, particularly at low speeds. This is true for deadbeat-direct torque and flux control, which directly manipulates the volt-second vector sourced by inverters, as well as for indirect field oriented control drives. This paper introduces a real-time sensing scheme to measure the motor terminal volt-second vectors for each switching period with negligible phase lag. Based on the volt-second sensing, a model reference adaptive system-based approach is developed to decouple the volt-second errors from inverter nonlinearity, and dc bus voltage fluctuation and measurement error. By delivering an accurate volt-second vector for each switching period, torque and flux control accuracy, self-sensing performance, and parameter estimation accuracy are significantly enhanced. [ABSTRACT FROM AUTHOR]

This paper proposes a multilevel shunt active power filter (SAPF) to deal with either harmonic current compensation or reactive power compensation. Such a device can reduce the harmonic distortion at the grid currents provided by nonlinear loads located in stiff systems. The proposed SAPF is based on three-phase bridge converters connected to cascaded single-phase transformers. The transformer arrangement permits the compensator to use a single dc-link unit, which simplifies the control strategy and the number of sensors. The multilevel waveforms are generated by using a suitable pulse-width modulation (PWM) strategy associated with the transformer turns ratio. Modularity and simple maintenance make the proposed SAPF an attractive solution compared with some conventional configurations. The model, the PWM technique, and the control strategy are presented, as well as studies considering harmonic distortion and semiconductor losses estimation. Simulation and experimental results are presented in order to validate theoretical approaches. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical harmonic analysis of phase disposition (PD) and phase-shifted carrier pulse-width modulation strategies for modular multilevel converters (MMCs). It is shown that when these strategies are implemented on a per MMC arm basis, their spectral performances converge because of cancellation of odd carrier sideband groups between each phase leg's arms. An improved PD modulation strategy is then presented that uses a single PD modulator for the entire phase leg, followed by a state machine decoder that evenly distributes switching pulses to all submodules across the phase leg upper and lower arms to balance the distribution of submodule commutation events. The resulting strategy achieves optimum phase leg PD spectral performance and also achieves natural voltage balancing of the MMC submodules. All theoretical findings are supported by simulation and experimental results obtained using a five-level MMC prototype. [ABSTRACT FROM AUTHOR]

Three-phase inverters in uninterrupted power supply, electric vehicles, and hybrid electric vehicles use an intermediate dc-link electrolytic capacitor, which has reliability issues and is one prominent cause of inverter failure and limited life. The large volume of an electrolytic capacitor increases the size and cost of the system. Recent research on electrolytic capacitorless inverters using six-pulse modulation technique along with high-frequency power conversion has attempted to address this issue. However, closed-loop operation and control has some issues due to capacitorless dc-link. In this paper, closed-loop operation, design, and implementation of an electrolytic capacitorless inverter is presented. A proof-of-concept 1-kW hardware prototype has been built and tested in a laboratory under different loading conditions. In total, 98% rated efficiency of the inverter is obtained with total harmonic distortion within 2%. Transient results during start-up and load change are smooth, demonstrating safe operation of the inverter. [ABSTRACT FROM AUTHOR]

Resonant converters used as coil drivers in inductive links generally operate efficiently at optimum switching conditions for constant load values and ranges. Changes in load and range can shift the operation of the coil driver to a nonoptimum switching state which results in higher switching losses and reduced output power levels. This paper presents a method to adapt to variations in range for a Class E inverter used as a coil driver in a wireless power transfer (WPT) system based on inductive coupling. It is shown that by controlling the duty cycle of the inverter's switch and the value of its dc-feed inductance, the Class E inverter can be tuned to operate at optimum switching conditions as the distance between the coils of the WPT system changes. Mathematical analysis is presented based on a linear piecewise state-space representation of the inverter and the inductive link. Extensive experimental results are presented to verify the performed analysis and validity of the proposed tuning procedure. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm that enables single-sensor operation of vector-controlled three-phase permanent-magnet-synchronous-motor voltage source inverter (VSI)-based drive systems. The closed-loop operation is performed through measuring only the VSI dc-link current. The measured VSI dc-link current is fed to a space-vector-based lookup table, which reconstructs the motor line currents. Three Luenberger-style observers are used to filter out the reconstructed motor line currents and estimate the rotor position and speed. The effect of observer bandwidth on the accuracy of the motor's estimated parameters is also investigated. The drive system's physical dynamic stiffness is used as a key metric to compare the drive system performance in single-sensor mode and fully sensored mode, in order to find the lowest steady-state speed limit for the single-sensor drive system operation. [ABSTRACT FROM AUTHOR]

The hybrid modular multilevel converter with cascaded full bridges (HMMC-CFB) is a recently proposed dc fault tolerant converter topology for high-power applications. It has a director part (DP) consisting of a series of connected half-bridge submodules, and a wave-shaping part (WSP) composed of a series of connected full-bridge submodules (FBSMs). The submodules in DP avoid high voltage stresses and improve synchronization between DP and WSP by slowing down the change rate of DP output voltage. This slowdown is achieved by using a trapezoidal reference signal for DP. The WSP attenuates the voltage harmonics produced by DP. However, the energy exchanged by WSP changes with modulation index, which may cause improper voltage regulation of the submodule capacitors. This paper proposes a new control technique to regulate the energy exchanged by WSP, which uses a variable slope trapezoidal reference signal of DP. To obtain this slope, the feedforward and feedback controllers are used. The feedforward controller gives the value of slope depending on the modulation index (mv) to keep the energy exchanged by WSP nearly equal to zero, whereas the losses and nonideality of the converter are taken care of by the feedback controller. This technique guarantees proper voltage regulation of the submodule capacitors for all modulation indices. The efficacy of the proposed technique is confirmed using simulations and experimentations. This paper also presents a circulating current suppressing controller for HMMC-CFB. The proposed control schemes and dc fault tolerant capability of HMMC-CFB are tested on a grid-connected model built in PSCAD. [ABSTRACT FROM AUTHOR]

This paper proposes and analyzes a new power electronics circuit topology for wireless inductive power transfer application using current-fed half-bridge converter with CCL-LC resonant network. The major focus is analysis and implementation of a new current-fed resonant topology with current-sharing and voltage doubling features. Generally, inductive power transfer circuits with current fed converter use parallel CL resonant tank to transfer power effectively through air gap. However, in medium power application, this topology suffers from a major limitation of high voltage stress across the inverter semiconductor devices owing to high reactive power consumed by loosely coupled coil. In proposed topology, this is mitigated by adding a capacitor in series with the coil developing series-parallel CCL tank. The power flow is controlled through variable frequency modulation. Soft-switching of the devices is obtained irrespective of the load current. For grid-to-vehicle or solar-to-vehicle, the converter is analyzed and detailed design procedure is illustrated. Experimental results are presented to verify the analysis and demonstrate the performance. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical study with experimental validation of a circulating-current suppression method for parallel operation of three-phase voltage-source inverters (VSI), which may be suitable for modular parallel uninterruptible power supply systems or hybrid ac/dc microgrid applications. The basic concept of the proposed circulating-current suppression method is to modify the original current references by using the current difference among the parallel inverters. In the proposed approach, both cross circulating current and zero-sequence circulating current are considered, and are added into the conventional droop plus virtual impedance control. In the control architecture, the reference voltages of the inverters are generated by the primary control loop, which consists of a droop control and a virtual impedance. The secondary control is used to compensate the voltage drop on the virtual impedance. Furthermore, a circulating-current control loop is added to improve the average current-sharing performance among parallel VSIs. Experimental results are presented to show the effectiveness of the proposed control method to suppress both cross and zero-sequence circulating currents. [ABSTRACT FROM AUTHOR]

Silicone carbide (SiC) power devices have been optimized in performance over the past decade. However, wide industry adoption of SiC technology still faces challenges from system design perspective. This paper demonstrates an integrated air-cooled three-phase SiC power block for industry applications. The key design aspects, such as high performance gate driver, low parasitic layout, optimized thermal management, as well as flexible control platform are addressed. Experimental results are provided to demonstrate the superior performance of the design. [ABSTRACT FROM AUTHOR]

This paper presents the design, implementation, and experimental validation of a method for fault prognosis for power electronics systems using an adaptive parameter identification approach. The adaptive parameter identifier uses a generalized gradient descent algorithm to compute real-time estimates of system parameters (e.g., capacitance, inductance, parasitic resistance) in arbitrary switching power electronics systems. These estimates can be used to monitor the overall health of a power electronics system and to predict when faults are more likely to occur. Moreover, the estimates can be used to tune control loops that rely on the system parameter values. The parameter identification algorithm is general in that it can be applied to a broad class of systems based on switching power converters. We present a real-time experimental validation of the proposed fault prognosis method on a 3 kW solar photovoltaic interleaved boost dc-dc converter system for tracking changes in passive component values. The proposed fault prognosis method enables a flexible and scalable solution for condition monitoring and fault prediction in power electronics systems. [ABSTRACT FROM PUBLISHER]

On-line condition monitoring is of paramount importance for multilevel power converters used in safety-critical applications. A novel on-line nonintrusive diagnostic method for detecting open-circuit switch faults in silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs)-based T-type multilevel converters is introduced in this paper. The principle of this method is based on monitoring the abnormal variations of the dc-bus neutral-point current in combination with the existing information on instantaneous switching states and phase currents. Advantages of this method include faster detection speed and simpler implementation compared to other existing diagnostic methods in the literature. Moreover, this diagnostic method is immune to the disturbances of inverter's dc-bus voltage unbalance and load unbalance. In this method, only one additional current sensor is required for measuring the dc-bus neutral-point current; therefore, the implementation cost is low. Simulation and experimental results based on a lab-scale 20 kVA adjustable speed drive with a three-level SiC T-type inverter validate the effectiveness and robustness of this novel diagnostic method. [ABSTRACT FROM PUBLISHER]

Short-circuit detection is a fundamental function of most inverters. In this paper, two new fast and easily implementable short-circuit detection approaches are presented. The first one offers a significantly accelerated desaturation detection. The second one allows a full inverter to be protected by only one short-circuit detection circuit. Both approaches are verified by simulations and hardware tests. [ABSTRACT FROM PUBLISHER]

In this paper, a sinusoidal excited four-phase switched reluctance machine (SRM) with modified dc-assisted windings is presented. The proposed four-phase SRM configuration with modified dc windings has a reduced number of controllable phases and power converter devices. The dc winding configuration is modified from its traditional form by taking advantage of the machine's inherent 90° phase shift between adjacent phases to achieve the desired simplification in the drive. Different power electronic converters for the proposed winding configuration have also been investigated. The proposed concepts are then verified through finite element analysis and an experimental prototype. [ABSTRACT FROM PUBLISHER]

This paper investigates the use of a model-predictive control strategy to control a direct matrix converter. The proposed control method combines the features of the classical model-predictive control and the space vector modulation technique into a modulated model-predictive control. This new solution maintains all the characteristics of model-predictive control (such as fast transient response, multiobjective control using only one feedback loop, easy inclusion of nonlinearities and constraints of the system, and the flexibility to include other system requirements in the controller), adding the advantages of working at fixed switching frequency and improving the quality of the controlled waveforms. Simulation and experimental results employing the control method to a direct matrix converter are presented. [ABSTRACT FROM PUBLISHER]

This paper proposes and investigates a multilevel ac six-phase motor drive. The system is composed of five isolated three-leg voltage source inverters feeding the open-end windings of an asymmetrical six-phase induction motor (SPIM), which is adequate to generate multilevel voltages for high-power systems with voltage rating restrictions. A simple space vector pulse-width modulation (PWM) based on three similar individual planes and its implementation by means of equivalent level-shifted PWM are presented. A space vector pattern with a high number of voltage vectors redundancies is obtained. These redundancies and the application sequence of the voltage vectors are selected to minimize the amount of changes in the switching states and to decrease the harmonic distortion of the generated voltages. The vector pattern of this optimal modulation is obtained by analyzing only one plane and applied in the same way to the three planes as if they were independent. The developed PWM techniques have low computational complexity and are suitable for low-cost hardware implementations. Simulation results are used to compare the proposed topology with a conventional configuration in terms of harmonic distortion and semiconductor losses. Experimental results demonstrate the feasibility of the proposed drive system. [ABSTRACT FROM AUTHOR]

Usually, the high-gain high-efficiency dc–dc converters consist of many passive components, which increases the order of the system. As the order increases, system modeling and control become more complex. Thus, there is a need for the simplification of the small signal modeling process of such converters. This paper presents a generalized small signal model and equivalent circuit for an $n$ th-order coupled-inductor-based high-voltage gain converters (CIHVGC) that can be conveniently used for the control design. The state variable representation of a generalized coupled inductor with p windings is included. A simplified step by step procedure to obtain small signal model using visual inspection is presented. Analysis is included and verified using simulations and experiments for the output voltage regulation of high-voltage gain converters. The usefulness and versatility of the proposed model is verified with three examples of high gain converters belonging to the CIHVGC family. All the analytical, simulation, and experimental details of this paper are presented. [ABSTRACT FROM AUTHOR]

For the high-voltage direct-current (HVDC) power transmission system of offshore wind power, dc/dc converters are the potential solution to collect the power generated by off-shore wind farms to HVDC terminals. The converters operate with high-voltage gain, high efficiency, and fault tolerance over a wide range of operating conditions. In this paper, an isolated ultrahigh step-up dc/dc converter with a scalable modular structure is proposed for HVDC offshore wind power collection. A flyback-forward converter is employed as the power cell to form the expandable electrically isolated modular dc/dc converter. The duty ratio and phase-shift angle control are also developed for the proposed converter. Fault-tolerant characteristics of the converter are illustrated through the redundancy operation and fault-ride-through tests. Redundancy operation is designed to maintain high operation efficiency of the converters and fault-ride-through operation improves the converter reliability under harsh operating conditions. Analytical studies are carried out, and a 750-W prototype with three modular cells is built and experimentally tested to verify the performance of the proposed modular dc/dc converter. [ABSTRACT FROM AUTHOR]

This paper proposes and investigates a new three-phase ac–dc–ac multilevel conversion system obtained from cascaded three-leg converters. Such configuration presents advantages in terms of reduced switch blocking voltages and consequently lower dc-link voltage rating. Operating principles, a pulse-width modulation (PWM) technique based on vector approach, and a control strategy are presented. The operation with different dc-link voltage values and a balancing method are discussed, and is supported by simulation and experimental results. The PWM technique is able to generate multilevel voltage waveforms, which permits reducing the switching frequency stress leading to reduced semiconductor losses. Simulation results are used to compare the proposed configuration with a conventional solution in terms of harmonic distortion and semiconductor losses. Experimental results demonstrate the feasibility of the studied converter, and were obtained by using a downscaled prototype with insulated gate bipolar transistors with dedicated drives and a digital signal processor with appropriated plug-in boards and sensors. [ABSTRACT FROM PUBLISHER]

This paper presents a comparative evaluation of the loss and thermal performance of two advanced three-level inverter topologies, namely the partial silicon carbide (SiC) T-Type and the Hybrid-neutral-point-clamped (NPC), both of which are aimed at reducing the high switching losses associated with a conventional Si T-Type inverter. The first solution directly replaces the 1200 V primary Si IGBT switches with lower loss 1200 V SiC MOSFETs. The second solution strategically adds 600 V CoolMos FET devices to the conventional Si T-Type inverter to reduce the primary commutation losses. Semiconductor loss models, experimentally verified on calibrated heat sinks, are used to show that both variations can significantly reduce the semiconductor losses compared with the Si T-Type inverter. The results show that both alternatives are attractive if high efficiencies and reduced thermal stress are major requirements for the converter design. [ABSTRACT FROM PUBLISHER]

This paper proposes a multilevel series compensator (MSC) to deal with voltage sags/swells, harmonic compensation, or reactive power compensation. Such a device can be considered as a dynamic voltage restorer or a series active power filter (Series-APF). The MSC can improve the power quality of loads located in stiff systems. The configuration is based on three-phase bridge (TPB) converters connected by means of cascaded single-phase transformers. This arrangement permits the use of a single dc-link. A generalization for $K$ -stages in which $K$ -transformers are coupled with $K$-TPB converters is presented. The topology permits generating a high number of levels in the voltage waveforms with a low number of power switches in comparison with a classic topology. The multilevel waveforms are generated by the converters through a suitable pulsewidth modulation (PWM) strategy that takes into consideration the transformer turns ratios. Modularity and simple maintenance make the proposed MSC an attractive solution compared with some conventional configurations. Model, PWM strategy, and overall control are discussed in this paper. Simulation and experimental results are presented as well. [ABSTRACT FROM PUBLISHER]

Utilities implementing grid modernization programs or facing challenges of increased level of renewable integration are seeking tools that can provide distributed and dynamic Volt/Var control (VVC). This paper presents a distributed autonomous VVC approach that uses a large number of small rated var injection sources to convert a distribution feeder into a dynamically controllable VAR source. Field results from a 13-kV 6-MW distribution feeder with 91 distributed controllable VAR sources, each rated at 10 kVAR validate the proposed system-level control strategy to achieve independent control of volts and vars on distribution systems. [ABSTRACT FROM PUBLISHER]

This paper presents a case study of a medium-voltage three-phase capacitor bank (CB) energization, based on an unsynchronized switching scheme using three independent pole vacuum switches simultaneously commanded. The motivations are cost reduction and simplification of the switching scheme. The maximum current and voltage peaks during transients caused by connection of CB with three independent pole switches or a three-phase mechanically coupled switch are compared. A probabilistic assessment for the overcurrents and overvoltages based on Monte Carlo simulation is also performed. The obtained results show that three single-phase unsynchronized switches could be used in a CB, with good transitory response. [ABSTRACT FROM PUBLISHER]

Numerous industrial facilities involve the installation of load transformers with their respective loads. As these loads are engaged and disengaged, their transformers are also energized and de-energized, respectively. An inrush current, which typically occurs when a transformer is energized, can easily be observed for an online uninterruptible power supply (UPS) system feeding such loads. This paper proposes an online UPS system that eliminates the inrush current phenomenon caused by the switching-in of the load transformers. The UPS inverter specifically utilizes a fast acting current control scheme which enables it to regulate the load current during all energizing conditions of the load transformer connected to the UPS system. Experimental results are provided to validate the effectiveness of the proposed UPS system. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel single-switch dc/dc converter for the future renewable electric energy delivery and management system to implement the distributed renewable energy resources (DRER). The DRER is responsible for the maximum power point tracking of the photovoltaic panel (PV) module and also for the control of central energy storage device. Due to the characteristics of the PV module and the dc-bus, the single power stage must provide low current ripple in the input and output terminals, must operate with output current and voltage regulation, and present a high-voltage conversion ratio. To achieve such features, this paper proposes a novel integrated Boost–Zeta converter. To avoid a complex modeling and control, we propose a disaggregation concept for this. Experimental results are presented for the purpose of operating the converter and also for the operation of the system. [ABSTRACT FROM PUBLISHER]

One of the problems of the pulse-width-modulation (PWM)-controlled ac machines is the acoustic noise that could become unacceptable when used in sensitive environments. Random PWM (RPWM) in industrial and commercial adjustable-speed drives (ASD) results in the partial transfer of power from the discrete spectrum (narrowband noise) of the output voltage to the continuous spectrum (wideband noise), with advantageous effects on reducing the acoustic noise in the motor drive system. In this paper, the theoretical power spectrum analysis as the basis for RPWM is presented. Five state-of-the-art RPWM strategies, their voltage, current, and acoustic noise spectra characteristics are quantitatively evaluated. The PWM schemes and theoretical analysis are validated through a 2.2-kW 380-V 50-Hz ASD induction machine experimental setup. The results provide valuable data for practicing engineering community to choose the best option in real-world applications. [ABSTRACT FROM PUBLISHER]

In LLC-based onboard battery charging architectures used in plug-in electric vehicles (PEV), the dc link voltage can be actively regulated to follow the battery pack voltage so that the LLC converter can operate in proximity of resonant frequency and achieve high efficiencies over the wide range of battery pack voltage. However, conventional boost-type power factor correction (PFC) converters are unable to provide ultrawide dc link voltages since their output voltages should always be larger than their input voltages. This paper proposes a Silicon Carbide (SiC)-based onboard PEV charger using single-ended primary-inductor converter (SEPIC) PFC converter followed by an isolated LLC resonant converter. With the proposed charger architecture, the SEPIC PFC converter is able to provide an ultrawide range for dc link voltage, and consequently enhance the efficiency of the LLC stage by ensuring operation in proximity of resonant frequency. A 1-kW SiC-based prototype is designed to validate the proposed idea. The experimental result shows that the SEPIC PFC converter achieves unity power factor, 2.72% total harmonic distortion, and 95.3% peak conversion efficiency. The LLC converter achieves 97.1% peak efficiency and always demonstrates a very high efficiency across the ultrawide dc-link voltage range. The overall efficiency of the charger is 88.5% to 93.5% from 20% of the rated load to full load. [ABSTRACT FROM AUTHOR]

One of the most basic tasks for ship power system design is electrical load analysis, which is used to determine the required installed capacity of on-board power generators. Traditionally, the analysis is carried out based on considerations of investment cost and supply adequacy, while using a design of generators with the same rating. It does not consider the energy efficiency, thereby in some cases resulting in the generators operated at a lower efficiency under heavy loading conditions and high energy consumption. To enhance power generation efficiency and reduce energy cost, a new load analysis method for marine vessels is proposed in this paper. The relationship of operating efficiency and load factor of generators is mathematically modeled and considered in the analysis. The problem is formulated as a nondifferential combinational optimization problem, where the total generation cost during a whole voyage is minimized subject to system operation and technical constraints, in order to derive the optimal generator rated power and unit commitment using genetic algorithms. The results confirmed the validity of the proposed method through load analysis of a practical ship power system, as well as energy-saving benefits using the proper generator rated power and an accurate load model for power pumps. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of pulse width modulation (PWM) on the circulating current of parallel-connected four-pole inverters (FPIs). Detailed mathematical modeling shows that the common-mode voltage (CMV) outputs of PWMs are closely related to the circulating current, so this research presents the reduced CMV PWM techniques for FPIs to reduce the circulating current, and compares their performances with the conventional PWM schemes. This study also shows how the controller structure of FPI affects the use of PWM schemes and the resulting circulating current. Laboratory test results are provided to validate their effectiveness. [ABSTRACT FROM AUTHOR]

High-performance industrial drives typically do not simultaneously minimize machine losses and achieve fast transient torque dynamics. This paper introduces a deadbeat-direct torque and flux control algorithm that achieves decoupled control of air gap torque and stator flux linkage using an inverse machine model. The stator flux linkage serves as a separate degree-of-freedom to manipulate machine losses without compromising desired torque dynamics. Several loss minimizing techniques utilizing deadbeat-direct torque and flux control have been reviewed. Loss minimization has been evaluated for some certain classes of applications. Results show that loss minimization can be achieved by optimal selection of stator flux linkage trajectory while achieving the desired torque dynamic performance. [ABSTRACT FROM AUTHOR]

With low loss, fast switching speed, and high-temperature capabilities, silicon carbide (SiC)-based devices are beneficial to automotive power converters in terms of efficiency increase and size reduction. Nevertheless, as a result of fast switching transitions and low on-state resistance of SiC devices, SiC-based converters are prone to overshoots and oscillations on switching waveforms, with the presence of parasitic inductances in the circuit. The overshoots and oscillations further contribute to increased converter loss and EMI emissions. This paper aims to study the influence of parasitic inductances on the performance of SiC MOSFETs for automotive dc–dc converters from the loss and electromagnetic interference perspective. [ABSTRACT FROM AUTHOR]

Two new configurations of static ground power unit based on 5L active neutral point clamped (ANPC) and novel modular 9L-ANPC converter are proposed. First, a new level shifted phase-shifted carrier pulse-width modulation (LS-PSC-PWM) switching method for the 5L-ANPC converter is defined. By utilizing the proposed method, total harmonic distortion of output voltage is reduced in comparison with traditional PSC-PWM switching method. Then, a novel modular 9L-ANPC multilevel converter and its suggested modulation method is proposed in this paper. In comparison with traditional 9L-ANPC converter, the main advantages of proposed modular 9L-ANPC converter are halving the applied voltages on flying capacitors (FC), reduced number of FCs, and self-balancing of FCs, which is provided by suggested switching method. This results in reduction of the size and cost of converter, and makes it more feasible and reliable. Furthermore, inductance reduction of output LC filter enhances static ground power unit dynamic performances. The simulation and experimental results verified the feasibility and performance of proposed converters. [ABSTRACT FROM PUBLISHER]

Current sharing controller/functionality is commonly utilized for multiphase converters to achieve current balancing between converter phases. Conventional current sharing control schemes generally require sensing the current of each phase, leading to increased size and cost in addition to issues associated with current sensing inaccuracies. A sensorless current sharing control scheme is proposed in this paper that utilizes the difference between the input capacitor voltage ripple values to indicate the phases' current distribution status. The duty-cycle value of each phase is autotuned in a way to minimize the difference between the input capacitor voltage ripple values based on a single voltage sensing point, which results in equal current sharing with no need for current sensing. In addition, the input capacitor voltage ripple sensing does not need to be very accurate, and the sinusoidal frequency component of interest of the ripple is obtained by using a low-cost bandpass filter for improved ripple sensing resolution and noise immunity. Experimental results obtained from a digitally controlled two-phase synchronous buck converter prototype are presented to validate the feasibility of the proposed concept. [ABSTRACT FROM PUBLISHER]

Overall performance of the voltage source converters (VSCs) has improved during the recent years. Improvement of the VSCs along with the attractive features of the VSC-based high-voltage direct current (HVdc) transmission systems over the thyristor-based HVdc transmission systems make it possible to build multiterminal VSC HVdc transmission systems. However, the VSCs are vulnerable against dc-side faults and a method needs to be employed to interrupt the dc fault current. In this paper, three different configurations of solid-state dc circuit breakers (CB) for protection purposes are studied. Moreover, a new control method to protect the VSCs against the dc-side fault is proposed. The new method makes it possible to interrupt the dc fault current with the existing ac breakers on the ac-side or with the lower rating solid-state (SS) direct current circuit breakers (DCCBs). The performance of the SS DCCBs and the proposed method are studied using real-time digital simulator. [ABSTRACT FROM PUBLISHER]

In this paper, an electric vehicle (EV) battery charger with interleaved Landsman converter (ILC) followed by a flyback converter, is designed and evaluated for improved power quality (PQ) charging of battery. A built-in wave-shaping is obtained at the charger front-end due to improved PQ characteristics of ILC. This PFC converter consists of two Landsman converter cells, which are designed in discontinuous conduction mode (DCM) to share the input and output currents. The current sharing at input results into lower input current ripple as well as peak current stress through the switch, is reduced. This, further improves the input current harmonics profile. Moreover, the reduced output voltage ripple gives reduced rms current in the output capacitor. A phase shift PWM scheme (PSPWM) is used for ILC and the duty cycle for the switches is selected below 50%. This allows the ripple cancellation at line and load sides. The interleaving at PFC stage as well as DCM based design ensures a low cost charging solution as compared to the conventional Landsman converter (CLC) based chargers in this power range. However, the flyback converter provides the current control during the charging of the battery in constant current (CC) and constant voltage (CV) regions. The harmonics spectrum of mains current follows the recommended PQ regulations over a range of varying line voltages and loadings. [ABSTRACT FROM AUTHOR]

Transformerless inverters are getting popular in distributed photovoltaic power generation (PVPG) system due to its light weight, low cost, and higher efficiency in power conversion. However, the production of leakage current leads to severe electromagnetic interference and operational insecurity, which declines the reliability and efficiency of the overall system. Besides that many of the topologies have been addressed with real power injection capabilities in the literature. Therefore, in this paper, an improved hybrid-bridge (IH-B) inverter for transformerless PVPG system is proposed with 1) reduced leakage current by abolishing the fluctuations in common-mode voltage (CMV) due to switch junction capacitances and 2) reactive power capability with a modified sinusoidal pulsewidth modulation technique. This topology is constructed with the combination of bidirectional clamping branch and hybrid-bridge (H-B) inverter topology to maintain CMV at half of the dc-link voltage and ensure better quality of output waveforms at different power factors of the grid. Further, MATLAB simulation results of the IH-B and H-B topologies are presented and compared to prove the potential benefits of the proposed topology. Finally, a 500W prototype model is built and tested to validate the effectiveness of the IH-B topology in reduction of leakage current and reactive power capability. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) power electronic devices feature the advantages of fast switching speed, low conduction loss, and reliable operation in high temperature environment, etc. Due to the differences of parasitic parameters and threshold voltage between SiC mosfets and Si mosfets, crosstalk problem is easy to be triggered when SiC mosfets are applied to bridge topologies. In this paper, the crosstalk effect with different parasitic parameters of SiC mosfets is firstly analyzed, and then an improved active crosstalk suppression method for high-speed SiC mosfets is proposed. By using the proposed method, when the crosstalk occurs, the crosstalk voltage will be decreased by reducing the equivalent gate resistance and increasing the equivalent gate-source capacitance in an active way. Consequently, the crosstalk problem can be suppressed without affecting the switching speed. To verify the effectiveness of the proposed method, a prototype of a buck–boost converter is built and the proposed modified gate driver is applied to the half-bridge topology. Comparative experimental study is conducted and the crosstalk voltage is analyzed. The experimental results verify that effective crosstalk suppression is achieved. [ABSTRACT FROM AUTHOR]

A modular quasi-resonant bidirectional dc–dc converter composed of half-bridge gallium nitride modules (HBGM) with reduced switch voltage stress is proposed in this paper. By using an auxiliary capacitor, a resonant circuit is formed to shape the current and voltage so that zero-voltage switching at turn-on instant is achieved. Since the switching loss dominates the power losses in a high-frequency dc–dc converter, the soft-switching performance leads to a noticeable reduction in the total loss; so, the operating temperature will decrease, and consequently, size of the heatsink will be reduced. The proposed circuit takes advantage of enhancement-mode gallium nitride (eGaN) switches regarding their small on-resistance RDS(on), low gate charge, and fast switching speed to improve both efficiency and power density. The main performance issue of adopting GaN switches in a bidirectional dc–dc converter is the high voltage stress of GaN devices, which is handled by connecting the HBGM in the active-clamped stacked configuration, as well as optimizing printed circuit board layout design. Finally, a 1 kW, 600 V laboratory prototype operating at 100 kHz is implemented to validate the proposed concept. [ABSTRACT FROM AUTHOR]

Recently multilevel inverters (MLIs) have received wide attention from industry and academia, as they are changing into a viable technology for diverse applications. To produce high-quality output using less switch count, development of novel reduced switch MLI (RS MLI) topologies has been a focus of current research theme. This paper presents design and control of a switched-diode dual source single switch MLI (SDDS MLI). The generalized SDDS MLI is first designed using an asymmetric basic unit. Proposed SDDS MLI requires less switch count and driver circuit count compared with the few recently developed RS MLI topologies. To improve the voltage quality by eliminating targeted low-order harmonics, a modified version of fish swarm optimization algorithm is examined for computing optimum switching angles required to control the SDDS MLI. Moreover, suitability and superiority of the derived algorithm are established by comparing with traditional selective harmonic elimination techniques. The developed topology is investigated through several MATLAB simulations as well as experimental tests in the laboratory applying the modified control approach. [ABSTRACT FROM AUTHOR]

This paper presents an energy-recycling class-D low-side gate driver integrated circuit (IC), which can also perform 5-to-15-V level upconversion using a bidirectional flyback converter topology. The gate driver itself is a mini switching regulator that operates at 5–15 MHz to generate 1-μs transition time gate-switching waveforms. In order to maintain uniform charging/discharging currents during transitions, the embedded flyback converter operates in a pulse-frequency modulation mode while charging and in a pulse width modulation mode while discharging the gate node. The required pulses with digitally programmable frequencies and duty cycles are efficiently generated by a custom-designed IC fabricated in a 0.25-μm HV CMOS technology. Also, the presented analysis guides a way to achieve the desired transition time with the maximum efficiency. The prototype IC demonstrates 37.5% energy recycling while driving a 15-V insulated-gate bipolar transistor power switch with 105-nC gate charge at 20 kHz. [ABSTRACT FROM PUBLISHER]

The fault-tolerant multilevel converters are gaining increased interests for high-voltage direct current (HVDC) applications due to their ability to suppress the fault current during dc-side faults. However, most of these topologies use full-bridge submodules (FBSMs) resulting in the requirement of a large number of semiconductor switches. In this paper, a new generalized cross-connected SM (GX-SM) structure is presented, which requires lesser number of switching devices and provides the same functionality as the FBSM. A comparison of the switches required in the different converter topologies using FBSMs and GX-SMs is performed. The performance evaluation of two of the dc-side fault-tolerant converter topologies, namely alternate arm modular multilevel converter (AAMMC) and hybrid cascaded modular multilevel converter (HCMC) with the GX-SM, is performed using simulation studies done in PSCAD/EMTDC. The modulation and control schemes for these GX-SMs-based converters are presented. A new mixed-SM configuration of AAMMC is proposed which utilizes an optimal combination of GX-SMs and half-bridge SMs. The study results demonstrate the effectiveness of the proposed GX-SM structure, and satisfactory responses of the GX-SMs-based AAMMC and HCMC systems controlled using the presented modulation and control strategies under various system conditions. [ABSTRACT FROM PUBLISHER]

This paper proposes a simple, cost-effective, and efficient brushless dc (BLDC) motor drive for solar photovoltaic (SPV) array-fed water pumping system. A zeta converter is utilized to extract the maximum available power from the SPV array. The proposed control algorithm eliminates phase current sensors and adapts a fundamental frequency switching of the voltage source inverter (VSI), thus avoiding the power losses due to high frequency switching. No additional control or circuitry is used for speed control of the BLDC motor. The speed is controlled through a variable dc link voltage of VSI. An appropriate control of zeta converter through the incremental conductance maximum power point tracking (INC-MPPT) algorithm offers soft starting of the BLDC motor. The proposed water pumping system is designed and modeled such that the performance is not affected under dynamic conditions. The suitability of proposed system at practical operating conditions is demonstrated through simulation results using MATLAB/Simulink followed by an experimental validation. [ABSTRACT FROM AUTHOR]