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»

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»

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»

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»

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»

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»

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»

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»

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»

Dynamic wireless charging of electric vehicles (EVs) can significantly extend the EVs' driving range and consequently, the prospect of electrified transportation. In this paper, a comprehensive study is conducted to elaborate the constraints of real driving conditions and propose a solution that could cope with misalignment problem and the dynamics imposed by the charging process and by EVs passin... 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»

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»

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, 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»

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»

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 proposes a novel two-stage topology for a 6.6-kW on-board charger. The first stage, employing an interleaved bridgeless totem-pole ac/dc in critical conduction mode to realize zero-voltage switching, is operated at over 300 kHz. A bidirectional CLLC resonant converter operating at 500 kHz is chosen for the second stage. A variable dc-link voltage is adopted to track the wide battery vol... 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»

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»

In this paper, a unified virtual synchronous control (UViSynC) is proposed for multiterminal voltage-source converter (VSC)-high-voltage dc (HVDC) (MTDC) systems, which can: 1) realize grid synchronization of the VSC stations by mimicking the rotor behavior of synchronous generators with the dynamics of dc grid and dc capacitor considered and 2) ensure the stable operation of the MTDC system that ... View full abstract»

The dc-dc modular multilevel converter (dc-dc MMC) with a medium-frequency ac-link transformer is a promising candidate for the modern electric ship medium voltage dc power system to provide galvanic isolation, flexible voltage regulation, and fault ride through ability. However, the steady states and dynamics of such an isolated dc-dc MMC are rather complicated because it contains many state vari... 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»

Quasi Z-Source inverter (qZSI) is becoming a popular inverter topology that can buck or boost input voltage without a DC-DC converter and hence can be used in transformerless configuration. Due to its single stage conversion, the qZSI can be used as an efficient transformerless grid-tie inverter. However, the common mode current is a major problem in transformerless topologies due to the absence o... 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»

The instability induced by high voltage direct current (HVdc) contingencies is challenging operation of ac/dc synchronous system. The asynchronization of ac/dc synchronous system can be a promising strategy for this concern which, however, is lack of practical applications. This paper analyzed the necessity of replacing the existing parallel ac/dc interconnection by pure dc interconnection in Chin... View full abstract»

Fault ride-through (FRT) control and protection are of vital importance for a modular multilevel converter-based high-voltage direct current (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 submodule-based MMC-HVDC system. It is suitable for both PTP... View full abstract»

Protection against short-circuit faults remains a major technical challenge in increasingly popular dc power networks. This paper describes a new concept of a self-powered dc solid-state circuit breaker (SSCB) with one or more normally on SiC JFETs as the main static switch and a fast-starting isolated dc/dc converter as the protection driver. The new SSCB detects short-circuit faults by sensing i... View full abstract»

When a single-line-to-ground (SLG) fault occurs on the ac side of the modular multilevel converter (MMC) in an high-voltage direct-current transmission (HVDC) system, it results in the ac-side voltage sag and leads to an instantaneous reduction of the MMC power capacity. Thus, it calls for the fault ride through (FRT) strategy to coordinate two MMC stations in the HVDC system to protect the MMCs a... 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»

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»

In this letter, a novel high step-up coupled-inductor DC-DC converter is presented. The proposed converter has an excellent feature which is the closer the turn ratio to 1, the higher the gain of the converter is, furthermore the lower the voltage stress of the switch is. Duty cycle and turn ratio of coupled inductor together determine the voltage gain of the converter, thus it can achieve any wan... View full abstract»

An analysis of control structures for modular multilevel converters (MMCs) used in high-voltage direct current (HVDC) applications is addressed. In particular, this paper focuses on the case of a point-to-point link with master-slave control, considering an energy-based scheme (also known as closed loop or energy controlled) for the MMC, meaning that the internal energy of the converter is explici... View full abstract»

Wireless power transfer chargers for electric bicycles (EBs) have many advantages over transitional plug-in systems. However, to meet the charge requirements, the traditional charger needs a dedicated inverter to achieve constant current (CC) output or constant voltage (CV) output. A hybrid topology-based EB charging strategy is proposed using a single high-frequency inverter (HFI) to charge massi... 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»

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»

In this paper, a novel isolated dc-dc converter topology for medium-voltage (MV) applications is proposed by combining the advantages of resonant converters and dual active bridge (DAB) converters. In normal load scenario, this converter operates in an open loop resonant mode with a fixed switching frequency equals to the resonant frequency of the series resonant tank. Thus, zero voltage turn on a... View full abstract»

For three-phase LCL-type grid-connected converter, when it is attached to weak grid, current control interacts with phase-locked loop (PLL) via point of common coupling voltage. Consequently, PLL dynamic might deteriorate grid current control and even result in system instability. However, the conventional design method of current controller neglects the impact of PLL, and therefore, it is hard fo... 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»

Leakage current reduction is crucial for the transformerless photovoltaic inverters. The conventional three-phase current source H6 inverter suffers from the large leakage current, which restricts its application to transformerless PV systems. In order to overcome the limitations, a new three-phase current source H7 (CH7) inverter is proposed in this paper. Only one additional Insulated Gate Bipol... View full abstract»

This paper presents a generator emulation control (GEC)-based method to provide synthetic inertia with a voltage source converter-based high-voltage direct current (VSC-HVdc) converter station, and furthermore, a coordinated control strategy for VSC-HVdc connected offshore windfarms (OWFs) to achieve enhanced ability of serving synthetic inertia. Given that the increasing penetration of renewable ... 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»

This paper proposed a fast and robust control strategy for a wireless power transfer system using primary side control. First, a sinusoidal reference trajectory signal was generated by analyzing the properties of the vector fields associated with all possible configurations of the primary power converter. Then, a switching controller was designed based on the switching behavior of the converter an... View full abstract»

Data centers demand high-current, high-efficiency, and low-cost power solutions. The high-voltage dc distribution power architecture has been drawing attention due to its lower conduction loss on cables and harnesses. In this structure, the 380-12 V high output current isolated converter is the key stage. This paper presents a 1-MHz 1-kW LLC resonant converter using GaN devices and planar matrix t... View full abstract»

On-chip power supply distribution faces the challenges of high and fast-changing load current, limited metal layers and decoupling capacitors, efficiency, and thermal issues. This paper mainly discusses system-level design considerations of both distributed and centralized fully integrated voltage regulators. In particular, a ring-shaped switched-capacitor dc-dc converter that has a unity-gain fre... View full abstract»

The second-order generalized integrator (SOGI) has been widely used to implement grid synchronization for grid-connected inverters, and from grid voltages, it is able to extract the fundamental components with an output of two orthogonal sinusoidal signals. However, if there is a dc offset existing in the grid voltages, the general SOGI's performance suffers from its generated dc effect in the lag... View full abstract»

This paper proposes an improved vector space decomposition current control scheme for dual three-phase permanent magnet (PM) synchronous motors having two sets of three-phase windings spatially shifted by 30° electrical degrees. A proportional-integral (PI) and resonant (second) controller is developed for eliminating the current unbalance in αβ subplane, which is effective irrespective of the deg... View full abstract»

In this paper, a high-frequency isolated bidirectional three-level dc-dc converter is proposed for battery charging/discharging applications. To reduce the circulating loss, a double pulse-width modulation (PWM) plus double-phase-shifted control with voltage matching control is proposed. Zero voltage switching (ZVS) for all switches can be obtained throughout full-load range even at no-load condit... View full abstract»

This paper discusses the design of a 10 kV and 200 A hybrid dc circuit breaker suitable for the protection of the dc power systems in electric ships. The proposed hybrid dc circuit breaker employs a Thompson coil based ultrafast mechanical switch (MS) with the assistance of two additional solid-state power devices. A low-voltage (80 V) metal-oxide-semiconductor field-effect transistors (MOSFETs)-b... View full abstract»