IEEE Journal of Emerging and Selected Topics in Power Electronics

Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimete... View full abstract»

In order to reduce size and cost, high-order passive filters are generally preferred in power converters to cancel out high-frequency harmonics caused by pulsewidth modulation. However, the filter resonance peaks may require the use of passive dampers to stabilize the interactions between the load and source impedances. Furthermore, the stabilizing effect is more difficult to be guaranteed for cos... View full abstract»

Wind power is still the most promising renewable energy in the year of 2013. The wind turbine system (WTS) started with a few tens of kilowatt power in the 1980s. Now, multimegawatt wind turbines are widely installed even up to 6-8 MW. There is a widespread use of wind turbines in the distribution networks and more and more wind power stations, acting as power plants, are connected directly to the... View full abstract»

Operational controls are designed to support the integration of wind and solar power within microgrids. An aggregated model of renewable wind and solar power generation forecast is proposed to support the quantification of the operational reserve for day-ahead and real-time scheduling. Then, a droop control for power electronic converters connected to battery storage is developed and tested. Compa... View full abstract»

Inductive power transfer (IPT) has progressed to be a power distribution system offering significant benefits in modern automation systems and particularly so in stringent environments. Here, the same technology may be used in very dirty environments and in a clean room manufacture. This paper reviews the development of simple factory automation (FA) IPT systems for both today's complex applicatio... View full abstract»

The solid-state transformer (SST), which has been regarded as one of the 10 most emerging technologies by Massachusetts Institute of Technology (MIT) Technology Review in 2010, has gained increasing importance in the future power distribution system. This paper presents a systematical technology review essential for the development and application of SST in the distribution system. The state-of-th... View full abstract»

Various noncontacting methods of plug-in electric vehicle charging are either under development or now deployed as aftermarket options in the light-duty automotive market. Wireless power transfer (WPT) is now the accepted term for wireless charging and is used synonymously for inductive power transfer and magnetic resonance coupling. WPT technology is in its infancy; standardization is lacking, es... View full abstract»

This paper performs an extensive review on control schemes and architectures applied to dc microgrids (MGs). It covers multilayer hierarchical control schemes, coordinated control strategies, plug-and-play operations, stability and active damping aspects, as well as nonlinear control algorithms. Islanding detection, protection, and MG clusters control are also briefly summarized. All the mentioned... View full abstract»

This paper focuses on the output parallel dual active bridge (DAB) dc-dc converters in power electronic traction transformers (PETT). A model predictive control with current-stress-optimized (MPC-CSO) scheme based on dual phase-shift (DPS) is proposed to improve the dynamic performance, balance the transmission power, and realize the current stress optimization. The dynamic behavior of output volt... View full abstract»

Gallium nitride (GaN) power devices are an emerging technology that have only recently become available commercially. This new technology enables the design of converters at higher frequencies and efficiencies than those achievable with conventional Si devices. This paper reviews the characteristics and commercial status of both vertical and lateral GaN power devices, providing the background nece... View full abstract»

In this paper, the current status and the requirements of primary electric propulsion components-the battery, the electric motors, and the power electronics system-are reviewed. The future trends in the electric propulsion systems, battery charging, and the types of power trains are presented. Possible future electric vehicle powertrain systems based on lithium air battery and plug-in fuel cell ve... View full abstract»

This paper proposes a predictive power control algorithm that decouples active and reactive power for grid integration of photovoltaic (PV) systems using a quasi-Z-source inverter (qZSI). This is important to meet the emerging smart inverter requirements for grid interconnection. The proposed controller uses model predictive control (MPC) framework to ensure that the maximum available power is har... View full abstract»

Power electronics has progressively gained an important status in power generation, distribution, and consumption. With more than 70% of electricity processed through power electronics, recent research endeavors to improve the reliability of power electronic systems to comply with more stringent constraints on cost, safety, and availability in various applications. This paper serves to give an ove... View full abstract»

Modular multilevel converter (MMC) is one of the most promising topologies for medium to high-voltage high-power applications. The main features of MMC are modularity, voltage and power scalability, fault tolerant and transformer-less operation, and high-quality output waveforms. Over the past few years, several research studies are conducted to address the technical challenges associated with the... View full abstract»

The virtual synchronous generator (VSG) is a control scheme applied to the inverter of a distributed generating unit to support power system stability by imitating the behavior of a synchronous machine. The VSG design of our research incorporates the swing equation of a synchronous machine to express a virtual inertia property. Unlike a real synchronous machine, the parameters of the swing equatio... View full abstract»

In this work, an inverter-side current control strategy for grid-connected VSI with LCL filters is proposed based on a generalized predictive control (GPC) formulation as it has the advantages of fixed switching frequency, a systematic design procedure and low computational complexity. As the GPC strategy is a subtype of continuous-control-set model predictive control (CCS-MPC) strategies, a prope... View full abstract»

An AC/DC + Dual-active-bridge (DAB) circuit was found as one solution for the high-efficiency and high-power-density electric vehicle charger. One control option is to let AC/DC part only convert the grid voltage to a double-line-frequency folded sine wave, yielding near-zero switching loss of the AC/DC part and leaving the DAB stage to control both power factor and power delivery. Such a z... View full abstract»

SiC MOSFETs exhibit extremely fast switching characteristics, which are unfortunately accompanied by undesirable switching oscillations. In this paper, equivalent circuit models incorporating all parasitic elements are developed for the turn-ON and turn-OFF of a SiC MOSFET. Simple mathematical formulas are derived to provide the theoretical analysis of the switching oscillation phenomenon, and to ... View full abstract»

Small-signal stability in balanced three-phase systems is typically investigated by means of the generalized Nyquist stability criterion (GNC) that involves operations on the source and load subsystems' impedance matrices. Eigenvalues of the ratio of these impedance matrices should be calculated for stability judgment. This paper shows that for a power-electronics-based distributed power system, i... View full abstract»

The interconnection stability of a grid-connected voltage-source converter (VSC) can be assessed by the passivity properties of the VSC input admittance. If critical grid resonances fall within regions where the input admittance acts passively, i.e., has nonnegative real part, then their destabilization is generally prevented. This paper presents an overview of passivity-based stability assessment... View full abstract»

This paper presents three-phase switched-boost modified Z-source inverter (ZSI) topologies with improved boost capabilities. In the proposed ZSIs, the voltage gain is increased significantly by adding one auxiliary switch and one diode without using additional passive components. The concept is applied to traditional ZSI, discontinuous input current quasi-ZSI (qZSI), and continuous input current q... View full abstract»

In this paper, a control strategy for power flow management of a grid-connected hybrid photovoltaic (PV)-wind-battery-based system with an efficient multi-input transformer-coupled bidirectional dc-dc converter is presented. The proposed system aims to satisfy the load demand, manage the power flow from different sources, inject the surplus power into the grid, and charge the battery from the grid... View full abstract»

In this paper, a feedforward proportional carrier-based pulse width modulation (PWM) is proposed for the DC link control of the single phase cascaded H-bridge multilevel PV inverter. The conventional carrier-based PWM techniques, such as the phase-shifted PWM and the level-shifted PWM, require multiple individual DC voltage controllers for the individual maximum power point tracking (MPPT). Thus, ... View full abstract»

This paper proposes a modified configuration of single-phase Pack U-Cell (PUC) multilevel inverter in which the output voltage has higher amplitude than the maximum DC link value used in the topology as a boost operation. The introduced inverter generates seven-level AC voltage at the output using two DC links and six semiconductor switches. Comparing to cascaded H-bridge and neutral point clamp m... View full abstract»

This paper presents a method for minimizing the cost of vehicle battery charging given variable electricity costs while also accounting for estimated costs of battery degradation using a simplified lithium-ion battery lifetime model. The simple battery lifetime model, also developed and presented here, estimates both energy capacity fade and power fade and includes effects due to temperature, stat... View full abstract»

In this paper, a small-signal model of voltage source converter (VSC) is developed to investigate the stability of dc-link voltage control. This model contributes to representing the dc-link voltage dynamics characteristics of VSC integrated to weak grid. Effects of grid strength, operating point, and control loops' interactions on the performance of VSC are taken into consideration. Based on the ... View full abstract»

A method for transfer function based modeling offering an in-depth insight into the systemic behavior of wind energy conversion systems (WECS) is developed. The originally nonlinear behavior of the drive system covering turbine, permanent magnet synchronous generator, and power electronic converter is rearranged and linearized resulting in a compact transfer function description. The locations of ... View full abstract»

This paper reviews the trends in wind turbine generator systems. After discussing some important requirements and basic relations, it describes the currently used systems: the constant speed system with squirrel-cage induction generator, and the three variable speed systems with doubly fed induction generator (DFIG), with gearbox and fully rated converter, and direct drive (DD). Then, possible fut... View full abstract»

A three-phase modular multilevel dc-dc converter is proposed and analyzed for power electronic transformer (PET) applications. Similar to a dual active bridge converter, the proposed converter comprises two three-phase inverters/rectifiers, coupled via a medium frequency (MF) transformer. The modular multilevel converter structure is used in the medium-voltage side to meet the high-voltage require... View full abstract»

This paper proposes a new single-phase five-level converter based on switched capacitor technique. The capacitor charging in the proposed converter is carried out in a self-balancing form which does not need closed-loop modulations or additional balancing circuits. The proposed topology is a voltage booster without using end side H-bridge for changing load voltage polarity. So, switching losses an... View full abstract»

In order to optimize the solar photovoltaic (PV) generated power using a maximum power point tracking technique, a dc-dc conversion stage is usually required in solar PV fed water pumping which is driven by a brushless dc (BLDC) motor. This power conversion stage leads to an increased cost, size, complexity, and reduced efficiency. As a unique solution, this paper addresses a single stage solar PV... View full abstract»

In this paper, the small signal stability issue of a dual-active-bridge (DAB) converter enabled dc microgrid is addressed. The derived impedance characteristic of the source DAB converter reveal that the stability of this dc grid is decided by the low-frequency terminal behaviors of integrated units, which is different from that of dc microgrids powered by other types of source converters. At this... View full abstract»

Roadway-powered electric vehicles (RPEVs) are attractive candidates for future transportation because they do not rely on large and heavy batteries but directly and efficiently get power while moving along a road. The inductive power transfer systems (IPTSs) that have been widely used for the wireless powering of RPEVs are reviewed in this paper. The development history of the IPTS is tracked from... View full abstract»

This paper describes an optimal operation scheme for energy management systems (EMS) using Gaussian process (GP) forecasting and model predictive control (MPC) in the context of grid-connected microgrids with local generation, loads and storage. The main objective of the control is to minimize the cost of energy taken from the grid. The microgrid consists of a PV panel and a battery energy storage... View full abstract»

The microgrid concept is gaining popularity with the proliferation of distributed generation. Control techniques in the microgrid are an evolving research topic in the area of microgrids. A large volume of survey articles focuses on the control techniques of the microgrid; however, a systematic survey of the hierarchical control techniques based on different microgrid architectures is addressed ve... View full abstract»

In this paper, a robust grid-current-feedback reso-nance suppression (GCFRS) method for LCL-type grid-connected inverter is proposed to enhance the system damping without introducing the switching noise and eliminate the impact of control delay on system robustness against grid-impedance variation. It is composed of GCFRS method, the full duty-ratio and zero-beat-lag PWM method, and the lead-grid-... View full abstract»

In this paper, a unified virtual synchronous control (UViSynC) is proposed for multi-terminal VSC-HVDC (MTDC) systems, which can a) realize grid synchronization of the VSC stations by mimicking the rotor behavior of synchronous generators (SGs) with the dynamics of dc grid and dc capacitor considered and b) ensure the stable operation of the MTDC system that interconnects very weak ac grids. Unlik... View full abstract»

Voltage-source converters (VSCs) are widely used in renewable energy sources as the grid interface, e.g., wind turbine generators and photovoltaics. These VSCs control the dc-link capacitor voltage and the reactive power output to track the reference values, which generally apply phase-locked loop (PLL) for grid synchronization. However, the dynamic performance of the conventional PLL can be deter... View full abstract»

In the islanded mode operation of a microgrid, a part of the distributed network becomes electrically separated from the main grid, while loads are supported by local sources. Such distributed energy sources (DERs) are typically power electronic based, making the full system complex to study. A method for analyzing such a complicated system is discussed in this paper. A microgrid system with two i... View full abstract»

Fault ride through (FRT) control and protection is of vital importance for modular multilevel converter based HVDC (MMC-HVDC) system when DC-side pole-to-pole (PTP) or pole-to-ground (PTG) fault occurs. In this paper, a FRT strategy by reversing DC voltage polarity is proposed for symmetrical bipolar full-bridge sub-module (FBSM) based MMC-HVDC system. It is suitable for both PTP and PTG fault. By... View full abstract»

This paper proposes an effective dc voltage and power-sharing control structure for multiterminal dc (MTDC) grids based on an optimal power flow (OPF) procedure and voltage-droop control implemented in the different hierarchical layers. In the proposed approach, an OPF algorithm is executed at the secondary control level of the MTDC grid to find the optimal reference values for the dc voltages and... View full abstract»

This paper presents a historical and philosophical perspective on a possible future for power electronics. Technologies have specific life cycles that are driven by internal innovation, subsequently reaching maturity. Power electronics appears to be a much more complex case, functioning as an enabling technology spanning an enormous range of power levels, functions and applications. Power electron... View full abstract»

This paper proposes a core loss model for filter inductors of power electronic converters. The model allows a computationally efficient analysis on the core loss of the inductor under the square voltage excitation and the premagnetization condition. First, the core loss of the filter inductor under buck chopper excitation is evaluated with the proposed model and compared with the conventional meth... View full abstract»

This paper presents the development of sequence impedance models for modular multilevel converters (MMC). The intended applications of the models include stability and resonance analysis of high-voltage dc transmission, static synchronous compensation, and other systems that use MMC. The basis of the modeling method is harmonic linearization that has been applied to other types of converters, but ... View full abstract»

This paper discusses the generalized theory of phase-shifted carrier pulsewidth modulation (PSC-PWM) for cascaded H-bridge (CHB) converters and modular multilevel converters (MMCs), provides a reasonable classification of the PSC-PWM, and extends the possible phase-shift angles to full range. First, the PSC-PWM for CHB converter is classified into two categories by phase-shift pattern. In addition... View full abstract»

The totem-pole bridgeless power factor correction (PFC) rectifier has recently been recognized as a promising front-end candidate for applications like servers and telecommunication power supplies. This paper begins with a discussion of the advantages of using emerging high-voltage gallium-nitride (GaN) devices in totem-pole PFC rectifiers rather than traditional PFC rectifiers. The critical-mode ... View full abstract»

A subsynchronous oscillation (SSO) phenomenon has been observed in a modular multilevel converter-based high-voltage dc (MMC-HVDC) transmission system for wind farm integration in the real world, which is independent of the type of wind turbine generator. This kind of oscillation appears different from those in doubly fed induction generator-based wind farm with series-compensation line or wind fa... View full abstract»

Field experience has shown that subsynchronous oscillation and harmonic resonance can occur between wind farms (WFs) and high voltage dc (HVdc) systems. The oscillations can appear in the presence of background harmonics due to the interaction between the wind energy conversion system's (WECS's) converter controller, HVdc converter controller, and the impact of the interconnection system impedance... View full abstract»

This paper presents a virtual synchronous control (VSynC) for doubly fed induction generator (DFIG)-based wind turbines (WTs) to provide inertia contribution in particular when integrated into weak ac grid with low short-circuit ratio (SCR). Different from the traditional vector control (VC) based on the widely used phase-locked loop synchronizing technique, VSynC is capable of synchronizing DFIG ... View full abstract»

It is expected that wide-bandgap devices like silicon-carbide MOSFETs and gallium-nitride HEMTs could replace Si devices in power electronics converters to reach higher system efficiency. This paper adopts the conventional half-bridge LLC topology to realize a 10-kW all-SiC bidirectional charger used in electric vehicles. Though it is a well-known topology for the unidirectional charger, it has no... View full abstract»