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In contactless energy transfer and vibration system (CETVS) for rotary ultrasonic machining, the energy is delivered to an ultrasonic transducer equipped with a rotary spindle shank through a loosely coupled transformer (LCT). The purpose of this paper is to present a simplified construct, referred to as self-compensation system, to overcome the drawbacks of external compensation elements occupying the limited shank space during the LCT's leakage inductance compensating and the transducer's capacitance compensating. The advantage of this approach is that the secondary leakage inductive reactance of the LCT and the capacitive reactance of the transducer are mutually compensated without an intermediate element, which conserves the spindle shank space and reduces the operating load of an LCT. In this paper, we first derive the mutual compensation equation between a transducer and an LCT. Then, for a given transducer, the structural parameters of an LCT are designed with theoretical calculations and simulation analysis. Experiments are conducted with the self-compensation system excited by a 50 V ultrasonic signal. The results show that the energy transfer efficiency of LCT reached 92.0%, the amplitude of the transducer reached $10.7\,\mu {\rm{m}}$ , when the CETVS is self-compensated. These results indicate that this self-compensation theory and design are feasible. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate how latency insertion method (LIM) can be used for real-time simulation of high switching frequency power electronics systems and how this approach can be implemented for scalable Field Programmable Gate Array (FPGA) execution. We first present a summary of the LIM and how this method can be developed into a solver for high-performance FPGA execution. We then present how common power electronics topologies—buck and boost—can be modeled using the LIM approach, followed by how the LIM model of a three-phase dc/ac converter is created. Afterward, we demonstrate the accuracy of the developed FPGA solver through a set of power electronic system examples, with each example compared with near ideal results of same example provided by a traditional electromagnetic transient type solver. We complete the paper analyzing the scalability of the proposed approach on FPGA devices, both in terms of achievable time step as well as of resource usage. [ABSTRACT FROM AUTHOR]

Conventional finite control set-model predictive control (FCS-MPC) applies single voltage vector within each control period. This leads to relatively high steady-state ripples and requires fast sampling rate. Additionally, enumeration-based optimal vector selection is computationally intensive. Recently, double-vector-based schemes have been proposed to improve the steady-state performance of FCS-MPC. However, they are usually complicated in vector selection and duty ratio calculation. In this paper, a universal multiple-vector-based MPC (UMV-MPC) is proposed, which achieves the same performance as the state-of-the-art double-vector-based MPC, but executes in a much more efficient and universal way. Unlike conventional FCS-MPC, enumerating process and state predictions for candidate voltage vectors are not required in the proposed UMV-MPC to select the best voltage vectors. In UMV-MPC, the optimal vectors and duty ratios are directly constructed from deadbeat control (DBC) based on space vector modulation (SVM), which is easy to follow and quick to use. The proposed UMV-MPC is not only more efficient than prior methods, but also reveals the inherent relationship between double-vector-based MPC and DBC with SVM. A comparative study of UMV-MPC and prior double-vector-based MPC is carried out in this paper. The theoretical analysis as well as simulation and experimental tests on a 2.2-kW induction motor drive are demonstrated to validate the effectiveness of the proposed UMV-MPC. [ABSTRACT FROM AUTHOR]

This paper focuses on the research of simulation model and experiment of a novel energy storage system (ESS). This novel ESS is dedicated to supplying power flow effectively for a new type of linear engine, which is used in alternative energy vehicle firstly. The control strategy has been proposed based on the ESS model, which adopts bidirectional four modes of operation to control the power flow. To sufficiently discuss the ESS dynamic behavior, the performance of the novel ESS is analyzed using simulations based on MATLAB/Simulink and experiments based on digital signal processor TMS320F2812. Finally, simulation and experimental results have verified the effectiveness of the novel ESS and the accuracy of the control strategy. [ABSTRACT FROM AUTHOR]

This paper presents a new predictive power-factor-correction (PFC) controller for series-interleaved three-level boost (TLB) converters. Compared to the state-of-the-art TLB PFC controllers, where a two-cycle prediction and a detection of an operating region are necessary, the proposed controller achieves a low total harmonic distortion of the input current by using a single equation to predict the input current in all operating regions of the converter, in just one operating cycle. The average current control is achieved by sampling at the peak of the triangular carrier. The proposed PFC controller significantly reduces the distortion of the input ac current near the zero-crossing points, resulting in a low total harmonic distortion of the input current. The operation of the proposed controller was evaluated, and its stability and robustness to parameter changes was confirmed analytically. The controller operating principles were verified in simulations and validated by experiments on a medium-voltage 50-kW converter prototype. [ABSTRACT FROM AUTHOR]

This paper presents a temperature-dependent SPICE model for SiC power MOSFETs. The model describes the static and dynamic behavior and accounts for leakage current and impact ionization. The technology-dependent mosfet parameters are extracted from characterization measurements and datasheets. SPICE standard components and analog behavior modeling blocks are adopted for the model implementation. The model ensures a good agreement with experimental data over a wide temperature range, even under out-of-safe-operating-area (SOA) conditions close to the failure occurrence. [ABSTRACT FROM AUTHOR]

Resonant power conversion leads to advantages such as soft switching and high-frequency operation; however, analysis and design of a resonant converter require an efficient methodology. In general, conventional methodologies use a design-oriented architecture, which requires previously specifications and iterative circuit-level simulations. This procedure is the simplest; notwithstanding, it can be time consuming and inaccurate for more complex systems, as resonant converters. This paper proposes a result-oriented architecture that is independent of specifications; in other words, real circuit parameters are waived in exchange for generalized results. A normalization procedure is proposed by using an equivalence transformation to modeling the system with a state vector composed of terms as the square roots of the stored energy in the reactive components. The system is represented in a dimensionless state-space model, in which the terms of the state-space matrices are composed of resonant parameters, such as normalized resonant frequencies and quality factor; thereby, the system is independent of circuit parameters, such as inductances, capacitances, and resistances. The sixth-order hybrid Ćuk converter is used to derivate the equations. Simulation results and an implementation of a 500-kHz hybrid buck converter are shown to compare theoretical, simulation, and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a finite-element-based simulation methodology to improve on multiscale modeling and analysis limitations of power electronics development. The method utilizes homogenization and nonmatching grid concepts to offer a high degree of flexibility and reduce computational effort. The applied homogenization method provides effective material properties to realize full-chip modeling performance without the need to model geometric details. The concept of nonmatching grids allows the inclusion of a subregion with substantially finer mesh than its surrounding regions. This allows the flexible integration of micrometer scale geometries with a high degree of detail within the full-chip model. Both concepts are thoroughly introduced and an application to a state-of-the-art power electronics semiconductor technology is presented. This paper focuses on electrothermal interaction and is experimentally verified on a dedicated test structure. The presented results provide electrothermal insights in current power electronic technologies and emphasize their potential to further improve the robustness and reliability of next generation technologies. [ABSTRACT FROM PUBLISHER]

In this paper, analytical expressions for waveforms and design relationships are derived for the class-E power amplifier with the MOSFET nonlinear drain-to-source parasitic capacitance under the subnominal operation, i.e., only zero-voltage switching (ZVS) condition, for any grading coefficient m of the MOSFET body junction diode and 50% duty ratio. Only the MOSFET nonlinear drain-to-source parasitic capacitance is used for the analysis of the class-E ZVS power amplifier, and its nonlinearity is determined by the grading coefficient m. The switch voltage waveform does not satisfy the class-E ZVS switching condition when only the linear shunt capacitance is considered. The grading coefficient m is used as an adjustment parameter that provides accurate design to satisfy the given output power and peak switch voltage simultaneously. Therefore, the grading coefficient m is the important parameter to satisfy the class-E ZVS condition and given design specifications, which is the most important result in this paper. Additionally, the output power capability and maximum operating frequency are affected by the grading coefficient m. The analytical expressions are obtained by considering the grading coefficient m as an adjustment parameter, which is validated by PSpice simulations and laboratory experiments. The measurement and PSpice simulation results agreed with the analytical expressions quantitatively, which denotes the usefulness and effectiveness of our obtained analytical expressions. [ABSTRACT FROM AUTHOR]

Recently, a magnetic pad called the tripolar pad (TPP) has been introduced for inductive power transfer (IPT) systems. This paper evaluates the effective coupling factor and leakage magnetic field of a 20-kW IPT system that uses a combination of TPP and circular pad (CP) topologies over a range of lateral displacements. The results show that the effective coupling factor and the leakage magnetic field of the TPP–TPP system are substantially better when the secondary is displaced away from ideal alignment. Leakage magnetic field is reduced up to 43% compared to the CP–CP system at the worst-case misalignment, which is due to the ability of the TPP–TPP system to generate and capture different types of magnetic field shapes. Simulation methods for both the TPP and CP are validated in the laboratory using a 2-kW system operating at 85 kHz. [ABSTRACT FROM PUBLISHER]

This paper proposes a star-channel modular multilevel converter (MMC). It overcomes the zero/low-fundamental-frequency operation issues of conventional MMC while not injecting the common-mode voltage (CMV). The proposed converter is characterized by the cross connections of upper three arms and lower three arms through two sets of star-channel branches. These star-channel branches rebalance the power among three phase legs, resulting in minimized submodule capacitor voltage ripples even at zero/low-fundamental-frequency operation without CMV injection. This feature enables the proposed converter to interface medium/high-voltage DC and variable-frequency AC systems. A 4160-V 1-MW simulation model is performed in MATLAB/Simulink, and a 208-V 5-kW experimental setup is constructed in the lab. Both of the simulation and experimental results verify the feasibility of the proposal. [ABSTRACT FROM PUBLISHER]

This paper presents a new three-phase phase-locked loop (PLL) system that primarily estimates the phase angles, frequency, and magnitudes of the a three-phase input signal and also provides a filtered version of the input. It is then extended to the estimation of sequence components, their magnitudes, and phase angles. As compared with the conventional three-phase PLL, this method does not suffer from errors that are caused by signal unbalance and dc offset. It also provides estimate for several other variables which are not included in the conventional three-phase PLL. As compared with the method of using three independent single-phase enhanced PLLs, the proposed method offers a simpler structure. Moreover, the estimated frequency is more accurate and smoother because it uses the information from all three phases to estimate a single value for frequency. The paper also presents a modification that makes the PLL parameters independent from the input signal amplitude. The same modification is applicable to existing methods such as conventional three-phase PLL. Simulation and experimental results are presented to confirm desirable performance of the proposed method. [ABSTRACT FROM AUTHOR]

This paper focuses on a topology optimization method for laminated busbars in power converters that minimizes the quantity of copper used while keeping the temperature under the allowed limits. Busbars are widely studied for adding their stray inductance to the commutation loop, which causes surge voltage across the power devices. However, the study of heat dissipation is essential to control hotspots in the busbar and preserve the converter components. Current density and temperature are sensitive to shape modifications; hence, topology optimization based on multiphysics simulations is an aspect to be considered when designing prototypes for a good cost performance ratio. The temperature is calculated by an electrothermal two-dimensional (2-D) finite element method (FEM) superposition approach. Busbar plates are modeled in 2-D since the thickness is constant. Furthermore, the different layers are related by the thermal equations reproducing the heat transfers regarding the overlap in the laminated busbar. Simulation results are validated by experimental tests. Comparison with 3-D FEM proves the 2-D approach to be faster while remaining accurate and a perfect method for topology optimization resolutions, which are very time consuming for three-dimensional (3-D) geometries. The busbar topology optimization is made by maximizing the energy transfer with the environment and by varying the electric and thermal conductivities of the mesh elements. Optimization leads to more than 50% volume reduction. [ABSTRACT FROM AUTHOR]

By the logical statements and linear inequalities, a new modeling method named bi-switching status modeling (BSM) method is presented to model the dc–dc converters in this paper. Compared with other modeling methods, such as the state-space averaging method and the mixed logical dynamical (MLD) method, first, the BSM method can describe continuous conduction mode and discontinuous conduction mode operations of the dc–dc converters as a unified bi-switching status model. Second, the BSM method is more precise than the state-space averaging method because there is no approximate assumption. Third, the constrains of the operating modes in the BSM method can be simplified as a consolidated inequality, which means that the model obtained by the BSM method is more concise than that obtained by the MLD method. Simulation and available experiments of a buck converter verify the effectiveness of the proposed BSM method. [ABSTRACT FROM PUBLISHER]

This paper presents an analytical model for input, output, and reverse capacitance of a normally on AlGaN/GaN high-electron mobility transistor (HEMT) with a gate field-plate structure, when the device is in the subthreshold regime. Together with the existing model for the output I–V characteristics, the proposed capacitance model provides the complete set of analytical equations that relate the physical design parameters to the electrical characteristics of the device. The model was verified by the experimental characterization of a HEMT. In comparison to the physics-based models implemented in Finite Element Analysis tools, the obtained capacitance model has substantially lower level of complexity and, therefore, it is more suitable for implementation into iterative design optimization algorithms. In order to verify the proposed model for such usage, the prototype of a high-frequency buck converter was built, using previously modeled GaN HEMT as the main switch. The hybrid analytical-behavioral power loss model of a high-frequency buck converter was implemented into Simplorer simulation tool, using the proposed physics-based model as the device description for the capacitive part. The efficiency measurements showed good agreement with the simulation results, even at 20 MHz of switching frequency in the low range of the output power. [ABSTRACT FROM AUTHOR]

This paper proposes a maximum torque per ampere control strategy for direct-torque-controlled interior permanent magnet synchronous motor drives. The proposed method is based on the solutions of a quartic equation, a motor model in the d-q rotating frame often used for the synchronous motor controllers, and a well-known equation for maximum torque per ampere control. Therefore, the proposed method does not use a lookup table that depends on parameters of the motor and that has to be created in advance. In addition, the proposed method can use the estimated parameters. Particularly, the variations of the d- and q-axes inductances can be estimated when the inductances are modeled as the functions of the d- and q-axes current. The simulation results validate that the proposed method can achieve the maximum torque per ampere control. In addition, the simulation and experimental results verify the accuracy improvement of the maximum torque per ampere control with the iterated calculation. [ABSTRACT FROM AUTHOR]

From the controller design framework, a simple analytical model that captures the dominant behavior in the range of interest is the optimal. When modeling resonant circuits, complex mathematical models are obtained. These high-order models are not the most suitable for controller design. Although some assumptions can be made for simplifying these models, variable frequency operation or load uncertainty can make these premises no longer valid. In this study, a systematic modeling order reduction technique, slowly varying amplitude and phase (SVAP), is considered for obtaining simpler analytical models of resonant inverters. SVAP gives identical results as the classical model-order residualization technique from automatic control theory. A slight modification of SVAP, slowly varying amplitude derivative and phase (SVADP) is applied in this paper to obtain a better validity range. SVADP is validated for a half-bridge series resonant inverter and for a high-order plant, a dual-half bridge series resonant inverter giving analytical second-order transfer functions for both topologies. Simulation and experimental results are provided to show the validity range of the reduced-order models. [ABSTRACT FROM PUBLISHER]

Computationally efficient high-frequency circuit models of long cables are necessary for accurate analysis of electromagnetic effects in power converter systems. In this paper, an advanced modeling technique utilizing different natural symmetries present in industrial power cables is introduced, resulting simultaneously in a significant reduction of the model complexity and an improved model precision as compared to the previously developed modeling methodology. Additionally, a method for extraction of the cable's per-unit-length parameters is derived allowing scalability of the developed model to arbitrary lengths for the cable of the same type. The developed methodology is validated by comparing the results obtained using simulations with the measurements in both frequency and time domain. [ABSTRACT FROM PUBLISHER]

In this paper, average modeling and analysis of a dual-supercapacitor bank, actively balanced by a bidirectional buck–boost converter, is presented. In such a system, natural balancing is achieved when the converter is operated in open loop with 50% duty cycle, eliminating the need for measuring the voltage of each storage device. Nevertheless, excessive currents arise even for slight voltage misbalance because of the highly underdamped nature of the system. In order to remedy this drawback, bidirectional pulse-by-pulse inductor current limitation is introduced, which is equivalent to adding a peak-current-mode-like control loop to the system. Since the duty cycle never exceeds 50%, compensation ramp is not required to maintain stability. On the other hand, while the uncontrolled system dynamics is linear, introducing the current limit mechanism turns the closed-loop dynamics into a nonlinear one, burdening the analysis task and thus calling for suitable average model to perform fast simulations for system analysis. Therefore, dynamical equations of the system are developed in order to derive the switching-cycle-averaged model and reveal the tradeoff between current limit level, balancing time and efficiency for the worst case of imbalance. Simulations and experiments support the presented findings. [ABSTRACT FROM PUBLISHER]

A recently reported modeling methods for a switched capacitor converter either assume output as “firm” voltage or a resistor to facilitate calculation. When the size of output filter capacitor is moderate, accompanied by noticeable output ripple, previous modeling results may not provide accurate prediction and design guidelines. In this paper, a new modeling technique taking into account the output capacitor effect is proposed for simple dual-phase switched capacitor converters without complex coupling loops. The proposed model employs transient calculation, takes charge redistribution phase into account, and includes the duty cycle, switching frequency as well as output capacitor simultaneously in the final output impedance formula, which enhances accuracy of the model. It is suitable for interleaved and noninterleaved switched capacitor converters. The simulation and experimental results for the unity gain SC converter are provided to verify the proposed theory. [ABSTRACT FROM PUBLISHER]

This paper presents an online procedure for the automatic search of the maximum-torque-per-ampere operating region for a synchronous reluctance motor. The algorithm is based on a signal-injection method with a random-based perturbation pattern applied to a common direct-torque-controlled drive. Among motor parameters, only the stator resistance is required to perform the automatic procedure. Simulations and experimental results are presented in the paper, demonstrating the benefits of the proposed algorithm. The solution is easily extended to any ac drive. [ABSTRACT FROM PUBLISHER]

The paper aims at clarifying the carrier-trapping influence on the electrical characteristics of silicon carbide (SiC) power MOSFETs and its inclusion in the simulation of SiC power mosfet-based circuits. Special focus is given on the degradation of the switching characteristics due to carrier trapping at SiC/SiO2 interface defects. A compact SiC power mosfet model, considering the trap density in the framework of a complete surface-potential description, has been developed by for accurate circuit simulation including power-loss prediction. The carrier trapping is verified to cause a switching delay, which results in switching loss increase. To achieve low power loss, trap-density reduction is shown to be vital. The maximum allowable trap density, which does not affect switching power loss, is discussed. [ABSTRACT FROM AUTHOR]

A simplified pulse width modulation (PWM) strategy for a neutral-point-clamped three-level converter with unbalanced dc links is proposed in this paper to achieve high-quality line-to-line output voltages and to maximize the linear modulation range. The simplified strategy takes the direct output voltage modulation by calculating the special solutions of the voltage–second balance equations without detecting the position of the reference vector in the asymmetrical and complicated space voltage vector diagrams to reduce the calculation time. A novel solution based on the state transition is proposed to extend the maximum linear modulation index to 1.15. Furthermore, the asymmetric control of the split dc link by the proposed PWM is implemented by adjusting the special solutions. The difference between the conventional space vector PWM and the proposed strategy is conducted to illustrate the advantages of the simplified strategy. The effectiveness of the proposed modulation strategy is verified by simulation and experiment results. [ABSTRACT FROM PUBLISHER]

This paper introduces a multiple-input multiple-output modular multilevel dc–dc converter (MIMO-MMC) and its associated control scheme. The proposed topology has a bidirectional structure and may be utilized in both low- and high-power applications ranging from approximately 100 W–10 MW. The modular structure of the MIMO-MMC enables efficient component utilization through module voltage and current sharing capabilities. The topology can supply or extract regulated power from an arbitrary number of controllable voltage nodes without requiring source or load multiplexing, resulting in minimized filtering requirements. The MIMO-MMC's structure is described, and the steady-state operation of the converter is theoretically analyzed. The dynamic models of the converter for both step-down and step-up configuration are derived and employed to devise an effective control algorithm for closed-loop operation. A general method is provided for stability analysis of the proposed closed-loop system followed by a case study verifying stability of the system at different operating points. The steady-state operation and dynamic response of the converter under both configurations is investigated through simulation and experiment. [ABSTRACT FROM PUBLISHER]

This paper presents results on behavior modeling of a general purpose metal–oxide–semiconductor field-effect transistor (MOSFET) for simulation of power electronics systems requiring accuracy both in steady state and in switching conditions. Methods of parameters extraction, including nonlinearity of parasitic capacitances and steady-state characteristics, are based on manufacturer datasheet and externally measurable characteristics. The MOSFET template is written in the MAST language and simulated in the SABER simulator. Experimental validation of the N-channel power MOSFET-type IRFP240 (Fairchild Semiconductor) rated at 20 A/200 V is performed in a dc/dc boost converter. The main features of the developed model have been compared with the properties of an analytical MOSFET model and a general MOSFET model embedded to a SABER simulator. [ABSTRACT FROM PUBLISHER]

This paper proposes an individual phase current control (IPCC) method based on optimal zero-sequence current separation for star-connected cascade STATCOMs under unbalanced grid voltage. The IPCC is adopted to get better adaptation to unbalanced conditions. Each cluster of the cascade STATCOM has its own phase current control loop and dc-voltage feedback loop, and it can generate the necessary negative-sequence current automatically to rebalance power. However, the zero-sequence current which is unnecessary and harmful in star configuration is introduced in the process. An optimal zero-sequence current separation is presented to remove the zero-sequence current by reconstructing the reactive current command. This improved IPCC enables star-connected STATCOMs adapt to unbalanced conditions without the need for any power balancing algorithms. Also, the operation range of the proposed control method is analyzed. Simulation research studies are performed to verify the operation range analysis, and the experimental operation is tested on a 25-level ±10 Mvar/10-kV STATCOM product installed at a wind farm. [ABSTRACT FROM PUBLISHER]

The need for multidisciplinary virtual prototyping in power electronics has been well established, however, design tools capable of facilitating a rapid iterative virtual design process do not exist. A key challenge in developing such tools is identifying and developing modeling techniques which can account for 3-D geometrical design choices without unduly affecting simulation speed. This challenge has been addressed in this paper using model order reduction techniques and a prototype power electronic design tool incorporating these techniques is presented. A relevant electrothermal power module design example is then used to demonstrate the performance of the software and model order reduction techniques. Five design iterations can be evaluated, using 3-D inductive and thermal models, under typical operating and start-up conditions on a desktop PC in less than 15 min. The results are validated experimentally for both thermal and electrical domains. [ABSTRACT FROM PUBLISHER]

Voltage source back-to-back power converters are widely used in grid-tied applications. This paper presents a quasi-centralized direct model predictive control (QC-DMPC) scheme for back-to-back converter control without a dc-link outer-loop controller. Furthermore, the QC-DMPC is experimentally compared with a conventional proportional-integration (PI) dc-link controller-based DMPC (PI-DMPC) scheme. For the QC-DMPC scheme, the dc-link voltage is directly controlled by a grid-side predictive controller using a dynamic reference generation concept and load-side power estimation. For the PI-DMPC scheme, the dc-link voltage is controlled by an external PI controller. Both schemes are implemented on a field programmable gate array (FPGA)-based platform. Effectiveness of the proposed QC-DMPC is verified by both simulation and experimental data. Moreover, FPGA implementation issues (resource usage and timing information), dc-link control performance, and robustness to parameter variation of the two DMPC schemes are compared in detail. The results emphasize that the QC-DMPC may outperform the PI-DMPC scheme in normal operation but with a slightly higher usage of FPGA resources. However, PI-DMPC scheme is more robust when parameter variations are considered. [ABSTRACT FROM PUBLISHER]

Nowadays, point-of-load (POL) converters’ investments are counted as a main part in power management markets; especially the synchronous buck converters. Today's products forces designers to highly integrate POL converters by increasing the switching frequency; so the latest technology has used megahertz range to obtain this target. On the other hand, increasing switching frequency means increasing the switching losses. Therefore, it is very important to optimize the operating switching frequency tradeoff, which requires an accurate model taking in consideration the converter operating conditions. This paper presents an accurate mathematical loss model taking in consideration the physical behavior of the MOSFET switch in addition to the converter operating conditions. This model introduces accurate equations for every switching intervals and so accurate loss calculations. An integrated POL synchronous buck converter of 5 MHz, 5–1.8 V/3 A prototype is fabricated. The results of the proposed model are compared with simulation and experimental results under variable operating conditions. Good matching between the mathematical, experimental, and simulation results are obtained. [ABSTRACT FROM AUTHOR]

Visualizing the magnetic flux paths for wireless power transfer systems enables researchers and engineers to understand the operations and design the geometrical dimensions of the practical systems. However, time-domain transient simulations of 3-D electromagnetic fields of complex wireless power transfer systems with multiple coil-resonators are extremely time-consuming. This paper describes a fast hybrid approach that combines the time-domain coupled circuit modeling and the magnetostatic analysis to form a fast time-domain analytical tool for studying complex wireless power transfer systems. The proposed methodology has been successfully applied to several wireless domino-resonator systems. For the first time, the time-varying magnetic flux variations of wireless power domino-resonator systems can be visualized in computer simulations. [ABSTRACT FROM AUTHOR]

The modular multilevel converter (MMC) is a newly introduced switch-mode converter topology with the potential for high-voltage and high-power applications. This paper focuses on the design and control methods for fault-tolerant operation using redundant submodules (SMs), which is one of the most important features in the MMC topology. By comparing three design schemes of redundant SMs, the most economic and reliable scheme is identified. In addition, a mathematical model of the MMC with arms containing different numbers of SMs is developed. Based on the identified scheme and mathematical model, an energy-balancing control strategy is proposed to keep the MMC operating normally under SM fault conditions. Finally, time-domain simulations of a 61-level MMC system are performed, using the PSCAD/EMTDC software, while experiments are carried out on a 41-level MMC prototype. The simulation and experimental results validate the design scheme, mathematical model, and proposed energy-balancing control strategy. [ABSTRACT FROM AUTHOR]

For flyback converter applications, an accurate model of the transformer is necessary for simulation studies, as well as a basis for model-based controller design. In general, transformer modeling has either focused on the winding model, using frequency-domain methods, or on the nonlinear core model, using time-domain methods. Nonlinear modeling is confined to the time domain and certain difficulties have precluded the use of time-domain methods for winding model estimation, resulting in the lack of integrated modeling approaches. This paper focuses on identifying a complete nonlinear dynamic model of a 3-winding transformer using time-domain system identification approaches. Our study demonstrates a possible way to handle the difficulties of working in the time domain and provides a model at least as accurate as that obtained with the frequency response data. In addition to the parameters of the Jiles-Atherton model, which is used to describe the nonlinear core behavior, the air-gap length is also computed from the experimental data to enhance the core model accuracy. The obtained transformer winding model, core model, and full model are experimentally verified. [ABSTRACT FROM AUTHOR]

This paper proposes a general methodology to analyze the interleaved pulse width modulation (PWM) dc–dc converter. A unified and simple model is constructed and the complete electrical behaviors of the interleaved PWM dc–dc converter could be predicted. Features of the interleaved PWM dc–dc converter are investigated based on this model. Insightful conclusions are derived and can be used to guide designs. This model could serve as a solid foundation for further research, and it is valid to all the common interleaved PWM dc–dc topologies. As an example of its applications, the input current of the interleaved boost converter is investigated in detail. Simulation and experimental results have successfully validated against theoretical analysis. [ABSTRACT FROM AUTHOR]

In this paper, a straightforward methodology to modeling high power factor (HPF) ac–dc converters is presented. The proposed methodology is based on the averaging technique directly applied to the converter under modeling. An averaged large-signal equivalent circuit is thus generated, which is useful to perform extremely fast simulations. From the large-signal model, both a steady-state and a small-signal analysis can be carried out to completely model the converter, achieving any desired steady-state characteristic and small-signal transfer function. The presented methodology is very intuitive and allows designers to achieve a natural understanding of the converter behavior. The methodology is illustrated with a HPF buck–boost converter operating in discontinuous conduction mode. Simulation and experimental results are provided to validate the proposed methodology. [ABSTRACT FROM AUTHOR]

DC hybrid power systems are of interest for future low emission, fuel-efficient vessels. In spite of the advantages they offer onboard a ship, they result in a complex, interconnected system, which requires effective analysis tools to enable a full realization of the advantages. Modeling and simulation are essential tools to facilitate design, analysis, and optimization of the system. This paper reviews modeling of hybrid electric ship components including mechanical and electrical elements. Power electronic converters are modeled by nonlinear averaging methods to suit system-level studies. A unified model for bidirectional converters is proposed to avoid transitions between two separate models. A simulation platform using the derived models is developed for the system-level analysis of hybrid electric ships. Simulation results of power sharing among two diesel generators, a fuel cell module, and an energy storage system are presented for three modes of operation. [ABSTRACT FROM AUTHOR]

Modular multilevel converters (MMC) are considered a top converter alternative for voltage-source converter (VSC) high-voltage, direct current (HVDC) applications. Main circuit design and converter performance evaluation are always important issues to consider before installing a VSC-HVDC system. Investigation into a steady-state analysis method for an MMC-based VSC-HVDC system is necessary. This paper finds a circular interaction among the electrical quantities in an MMC. Through this circular interaction, a key equation can be established to solve the unknown circulating current. A new steady-state model is developed to simply and accurately describe the explicit analytical expressions for various voltage and current quantities in an MMC. The accuracy of the expressions is improved by the consideration of the circulating current when deriving all the analytical expressions. The model's simplicity is demonstrated by having only one key equation to solve. Based on the analytical expressions for the arm voltages, the equivalent circuits for MMC are proposed to improve the current understanding of the operation of MMC. The feasibility and accuracy of the proposed method are verified by comparing its results with the simulation and experimental results. [ABSTRACT FROM AUTHOR]

In this paper, a novel generalized behavioral model and the corresponding parameter extraction procedure for single- and three-phase chokes are presented. The model takes into account common-mode and differential-mode behavior of the choke and can be applied to modeling all types of chokes used in electromagnetic interference filters for power electronics devices. Depending on the level of the model complexity, the model parameters can be obtained either from a straightforward equation-based or an optimization-based parameter extraction procedure. The accuracy of the model and the validity of the method are demonstrated on several examples of single- and three-phase chokes with ferrite and nanocrystalline cores. [ABSTRACT FROM AUTHOR]

This paper presents several of the problems encountered with vector-controlled single-phase induction motor (SPIM), and discusses about the complex implementation of a vector controlled SPIM drive. The vector-controlled symmetrical two-phase induction motor (TPIM) is presented as a viable replacement for the vector-controlled SPIM. The implementation of the proposed vector-controlled TPIM is simple compared to the vector-controlled SPIM. All the TPIM parameters can be calculated simply and precisely. The proposed strategy for TPIM is derived from the indirect vector control strategy used for three-phase ac machines. Several differences between the vector control strategies for the TPIM and for three-phase ac motor are discussed. The validity of the proposed vector-controlled TPIM was verified by simulations and experiments. [ABSTRACT FROM AUTHOR]

In this paper, three dc/dc ladder multilevel converters are compared. The first one is the classical ladder topology and the two other topologies presented are based on the classical one. A mathematical calculation of the output resistance and the gain of the converter as a function of the number of levels is carried out for the three topologies in order to estimate the voltage drop due to the output current. These calculations are validated with simulations and experimental results. Finally, the behavior of the three topologies is compared through experimental tests. Results show higher performance for the presented converters compared to the classical ladder. [ABSTRACT FROM AUTHOR]

A primary-side controlled universal-line flyback converter is widely used for its low-cost and low standby power advantages; however, conventional overpower protection schemes that feature primary-side control often experience inaccurate protection. In this paper, a novel scheme is presented, which achieves a very significant improvement in overpower accuracy while simultaneously meets a critical goal of adding no extra pin compared to conventional schemes when implemented in an IC. Experimental and simulation results verified the proposed strategy, and the scheme was implemented successfully in an IC. [ABSTRACT FROM AUTHOR]