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Multiphase variable-speed drives and generation systems (systems with more than three phases) have become one of the mainstream research areas during the last decade. The main driving forces are the specific applications, predominantly related to the green agenda, such as electric and hybrid electric vehicles (EVs), locomotive traction, ship propulsion, “more-electric” aircraft, remote offshore wind farms for electric energy generation, and general high-power industrial applications. As a result, produced body of significant work is substantial, making it impossible to review all the major developments in a single paper. This paper therefore surveys the recent progress in two specific areas associated with multiphase systems, namely power electronic supply control and innovative ways of using the additional degrees of freedom in multiphase machines for various nontraditional purposes. [ABSTRACT FROM AUTHOR]

Development of smart grid technologies has created a promising atmosphere for smart cities and energy trading markets. Especially, traditional electricity consumers evolve into prosumers who produce as well as consume electricity in modern power electric systems. In this evolution, the electric power industry has tried to introduce the notion of local energy markets for prosumers. In the local energy market, prosumers purchase electricity from distributed energy generators or the other prosumers with surplus electricity via a local power exchange center. For this purpose, this paper proposes joint geometric clustering and truthful auction schemes in the local energy markets. The proposed clustering scheme is designed for distribution fairness of the distributed energy generator for serving prosumers, where the scheme is inspired by expectation and maximization based unsupervised learning. Moreover, this paper proposes an auction mechanism for truthful electricity trading in a local energy market. In order to guarantee truthful electricity trading, the proposed auction mechanism is constructed based on the Vickrey–Clarke–Groves auction, which was proven to guarantee truthful operations. The Hungarian method is also considered in addition to the auction. The simulation results for the auction verify that the utilities of local market energy entities are maximized when the prosumers are truthful. [ABSTRACT FROM AUTHOR]

This paper describes a novel regenerative braking control scheme of electric power-assisted wheelchairs for safety driving on downhill roads. The "electric power-assisted wheelchair" which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people; however, it has no braking system to suppress the wheelchair's velocity and brings the dangerous and fearful driving particularly on downhill roads. Therefore, this paper proposes a navel safety and efficient driving control scheme based on the regenerative braking system. This paper applies the regenerative braking system with the step-up chopper circuit serially connecting two motors and realizes the velocity feedback control with the variable duty ratio so that it tracks the optimal velocity based on the Minimum Jerk Model. In addition, the dynamic braking system is also applied at the low-speed range instead of the regenerative braking in order to suppress the acceleration. Some driving experiments on the practical downhill roads show the effectiveness of the proposed control system. [ABSTRACT FROM AUTHOR]

In this paper, a new control system to regulate the reactive power supplied by a variable-speed wind energy conversion system (WECS), based on an induction generator fed by a matrix converter (MC), is presented. The control system discussed in this paper is based on an input current observer, implemented using an estimation of the modulation matrix, and a nonlinear control loop that regulates the displacement angle at the MC input. The reactive power capability of the proposed system is also investigated. The work presented in this paper demonstrates that, for the proposed WECS, the maximum reactive power supplied to the grid is about 40% of the nominal value. Experimental results obtained from an experimental prototype are presented in this paper. The performance of the system using a wind turbine emulator and typical wind profiles is discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes a novel control method for an asymmetrical-cascaded-multilevel-converter-based hybrid energy storage system (HESS), which includes one battery and several electrical double-layer capacitors (EDLCs). Traditionally, it is challenging to control the power distribution between different cascaded H-bridges by using different energy storage components as dc sources. In this paper, a feedforward space-vector-modulation (FFSVM) technique is used to distribute the active power between the battery and EDLCs. With the proposed voltage feedforward mechanism, the HESS can flexibly operate in the normal operation mode, the high-power output mode, and the reverse power absorption mode. The principle and effectiveness of the improved FFSVM technique are analyzed. Meanwhile, the state-of-charge-balancing mechanisms are introduced. The simulation results obtained in MATLAB/Simulink as well as the experimental results of a hybrid energy storage test bed based on the proposed system are presented to verify its performance. [ABSTRACT FROM PUBLISHER]

This paper describes how an electrical variable transmission (EVT) can be used as an alternative for mechanical continuously variable transmission (CVT) systems. An EVT is an electromagnetic power split device having two mechanical and two electrical ports. The speed ratio between both mechanical ports (rotors) can be varied in a continuously variable way, so that this machine can be used as an electromagnetic alternative for the mechanical push-belt and half-toroidal CVT. Its operating principle is based on splitting the power into an electromagnetic direct path and an electrical path involving two inverters connected back to back. Its potential use as a CVT is investigated by comparing experimental data against toroidal and belt CVT data from literature having comparable power ratings. To this end, measurements are performed on a prototype \text120-kW permanent magnet EVT. [ABSTRACT FROM AUTHOR]

Isolated high output current dc/dc converters are critical for power supplies in information technology industries. LLC converters with a matrix transformer are suitable for these applications due to their high efficiency and high power density. By pushing switching frequency up to MHz with GaN devices, planar matrix transformers with printed circuit board (PCB) windings are advantageous over conventional transformer designs, but the large interwinding capacitance of the PCB windings provides a critical coupling path for common-mode (CM) noise. In order to analyze the CM noise, the interwinding capacitance of the PCB windings is analyzed, and a related CM noise model is provided in this paper. To suppress the CM noise, shielding layers can automatically be inserted into the PCB windings between the primary and secondary windings in the fabrication process. This paper proposes a novel shielding technique, in which half of the shielding serve as the primary winding. The proposed shielding technique not only suppresses CM noise but improves the efficiency as well. The proposed shielding is verified by experiments on 1-MHz 400 V/12 V 800-W LLC converters with a peak efficiency of 97.7% and a power density of 900 W/in3. The proposed shielding reduces CM noise by 30 dB and improves full-load efficiency by 0.2%. [ABSTRACT FROM PUBLISHER]

Current imbalance in multistring light-emitting diodes (LEDs) is a critical issue. It may cause overcurrent in one or more LED strings, leading to rapid degradation. In this paper, a mixed high-order compensation networks-based wireless power transfer system is proposed to generate multiple constant current outputs. It is composed of an LCC resonant network in the transmitting side, a series resonant network, and multiple CLC resonant rectifiers in the receiving side. The CLC resonant rectifiers are connected in parallel to form multiple independent output channels, and each channel is then connected to an LED string. Based on the analysis of the T resonant circuit and the modeling of coupling coils, multiple constant output currents can be derived. As a result, current balance can be achieved, which is very suitable for driving multistring LEDs. The proposed system also offers a modular, scalable, and maintenance-free design, which can significantly reduce the construction cost and the control complexity. In addition, the inverter in the transmitting side can achieve zero phase angle. A laboratory prototype with dual independent output currents is built to verify the proposed method. The experimental results agree well with the theoretical analysis. [ABSTRACT FROM AUTHOR]

In order to increase the annual energy yield of a variable-speed wind energy conversion system (WECS), maximum power point tracking (MPPT) control is required at below the rated wind speed. However, the only aspect that has been paid attention to by most of the researchers is the way to accelerate the MPPT speed. In fact, the research of this paper finds out that the faster the MPPT speed is, the larger transient load the turbine shaft bears. Thus, attempts are first made to find out the relationship between the MPPT speed and the transient load through quantity analysis. Then, a principle to choose a proper bandwidth of the MPPT system is given out to optimize the transient load. Furthermore, to ensure that the system can track the varying winds at the designed bandwidth, the design details on how to make the MPPT bandwidth constant are also proposed in this paper. Finally, a 1.2-kW variable-speed WECS, which is based on a permanent-magnet synchronous generator, is established in the laboratory. Theoretical analysis is verified by experimental results performed by it. [ABSTRACT FROM PUBLISHER]

This paper introduces a voltage-controlled static magnetic device called magnetic flux valve. It is mainly used in a magnetic circuit to actively control the magnetic flux through the magnetic circuit. The magnetic flux valve has a laminated structure of two different types of layers made of a magnetostrictive material, e.g., amorphous alloy ribbon, and a piezoelectric material, e.g., piezoelectric sheet. The permeability of the magnetostrictive layers changes when an external control voltage applied to the piezoelectric layers changes, which is known as the converse magnetoelectric effect. A permeability change of the magnetic flux valve will lead to a change of the reluctance of the magnetic flux valve and the reluctance of the magnetic circuit containing the magnetic flux valve. As a consequence, the magnetic flux and/or its distribution in the magnetic circuit will change. There is a great potential to use the proposed magnetic flux valve to develop new equipment, such as tunable inductor and adjustable-voltage-ratio transformer for more flexible conversion and control of electric power in many applications. This paper presents the concept, magnetic properties, working principles, and applications of the magnetic flux valve. [ABSTRACT FROM PUBLISHER]

The finite control set model predictive control (FCS-MPC) for power electronic converters provides high dynamic performance, based on the limited number of inputs and accurate model of the converter. By applying this algorithm to multilevel converters such as a cascaded-H-bridge-based static var compensator (CHB STATCOM), the dynamic performance is degraded, because the optimized input is achieved by searching among a large set of switching combinations and redundancies. This paper proposes an FCS-MPC algorithm, which benefits high dynamic performance for the CHB STATCOM, despite the large set of inputs. The proposed FCS-MPC replaces the time-consuming optimization algorithm by solving Diophantine equations over the large set of switching combinations. The desired switching combination and all its redundancies are determined in a minimum execution time. The proposed FCS-MPC performance is validated by applying to two configurations: 1) a 15-level CHB STATCOM with energy storage capability for a short-term active power smoothing and reactive power compensation of a 10 MW fixed speed wind farm at medium voltage; and 2) an experimental seven-level CHB STATCOM at low voltage. [ABSTRACT FROM AUTHOR]

Designing a power supply of a newly built property, a modern investor has, at his disposal, a whole range of technologies, the skillful selection and application of which will minimize the total cost of supplying the facility with electrical energy and heat. Obviously, both capital and operating cost must be considered. Apart from renewable energy sources such as photovoltaics, wind turbines, heat pumps, or solar heating, classical technologies such as district heating, gas or diesel powered micro/mini-combined heat and power units, or gas boilers can be used. For the optimal use of a complex power system, electrical energy and heat storage may be necessary, as well as an advanced control system. The choice of the property power supply structure and the selection of technologies are extremely important, because this decision will impact the costs that will be incurred by the owner over the next few decades. This paper shows how to select the structure and parameters of the power supply for residential premises, taking into account the characteristics of electricity and heat consumption and weather conditions which influence both the energy consumption and renewable energy generation. The obtained solutions were analyzed depending on the availability of district heating and local generation and the adopted electricity tariff, as well as energy and capacity prices. [ABSTRACT FROM AUTHOR]

This paper studies the cascaded doubly fed induction machine, operating as a brushless variable speed constant frequency generator supplying an isolated load. In isolated electric supply, the amplitude and frequency of the output voltage of the generator should be stabilized during the speed and/or load changing. Despite the complexity of the generator model, a simple indirect field-oriented vector control is elaborated to meet the output voltage requirements. Experimental results validate the proposed control approach. The study is extended to reveal the behavior of the controlled system under unbalanced load. [ABSTRACT FROM AUTHOR]

In order to adapt to the single power supply system of an aircraft, this paper proposes and investigates a novel dual-winding fault-tolerant (DF) motor drive system based on the redundancy bridge arm for aerospace applications. The proposed DF motor offers the advantages of magnetic isolation, physics isolation, thermal isolation, and small cogging torque ripple, inhibiting the short-circuit current and high fault tolerance. The proposed DF motor drive can adapt to the single power supply system of the aircraft, reduce the drive cost, and reduce the number of independent power sources and power switches. In addition, it can improve the power density, the reliability, and the utilization rate of the drive. At the same time, the drive system has stronger fault-tolerant ability, and it can achieve the fault-tolerant control for a one-phase-winding fault or a multiphase-winding fault. To realize the short-circuit fault diagnosis performance, the diagnosis and processing method of the short-circuit fault has been investigated. Then, to realize the short-circuit fault-tolerant performance, a novel space vector pulsewidth modulation (SVPWM) fault-tolerant control strategy based on the short-circuit fault diagnosis and processing method is proposed. Finally, the performances of the DF motor drive have been verified by experiments. The research results verify the reliability and effectiveness of the proposed DF motor drive system based on the redundancy bridge arm and the SVPWM fault-tolerant control strategy. [ABSTRACT FROM AUTHOR]

In this paper, an integrated double buck–boost (IDBB) converter is proposed as a high-power-factor offline power supply for power-LED lamps. The IDBB converter features just one controlled switch and two inductors and is able to supply a solid-state lamp from the mains, providing high power factor and good efficiency. In this paper, the IDBB converter is analyzed, and a design methodology is proposed. It is demonstrated that, with a careful design of the converter, the filter capacitances can be made small enough so that film capacitors may be used. In this way, the converter mean time between failures can be made as high as that of the solid-state lamp. A design example for a 70-W converter supplied from a 230 V/50 Hz mains for street lighting applications is shown. Finally, experimental results from a laboratory prototype are also presented. [ABSTRACT FROM AUTHOR]

Competitive strategic bidding optimization is now a key issue in electricity generator markets. Digital ecosystems provide a powerful technological foundation and support for the implementation of the optimization. This paper presents a new strategic bidding optimization technique which applies bilevel programming and swarm intelligence. In this paper, we first propose a general multileader-one-follower nonlinear bilevel (MLNB) optimization concept and related definitions based on the generalized Nash equilibrium. By analyzing the strategic bidding behavior of generating companies, we create a specific MLNB decision model for day-ahead electricity markets. The MLNB decision model allows each generating company to choose its biddings to maximize its individual profit, and a market operator can find its minimized purchase electricity fare, which is determined by the output power of each unit and the uniform marginal prices. We then develop a particle-swarm-optimization-based algorithm to solve the problem defined in the MLNB decision model. The experiment results on a strategic bidding problem for a day-ahead electricity market have demonstrated the validity of the proposed decision model and algorithm. [ABSTRACT FROM AUTHOR]

This paper deals with the identification of mechanical backlash in drives. The development of a reliably working identification method is intended. The method presented in this paper is considered to be a necessary step toward the development of more complex diagnosis tools and condition monitoring systems that are demanded today in the area of servodrives. The main idea for identifying backlash is explained. Measurement results clearly point out the efficiency of the identification strategy proposed in this paper. Thus, the results of the identification can be utilized for the tuning of the controller or for the diagnostics of the actual state of the drive. [ABSTRACT FROM AUTHOR]

The open-loop control scheme presented in part I of this paper for a dual five-level-inverter-fed induction motor (IM) drive with two dc power supplies maintains dc-link capacitor voltage balancing and common-mode voltage (CMV) elimination throughout the operating range of the drive. The operating limitation of the proposed open-loop control scheme to take corrective action toward the existing unbalance in the dc-link-capacitor voltages is also pointed out in part I of this paper. As a solution to this, a simple closed-loop control scheme, which is based only on the switching-state redundancy, is proposed in this part of the paper. The proposed closed-loop control scheme not only prevents further unbalancing of capacitor voltages but also takes corrective actions to bring back the capacitor voltages in the balanced state. The proposed closed-loop scheme achieves dc-link capacitor voltage balancing and elimination of CMV together in the complete modulation range, including overmodulation of up to the 24-step operation. The proposed control scheme does not affect the output fundamental voltage generated by the inverter, as it effectively utilizes only the availability of redundant switching states of the inverter, and does not call for additional power circuit hardware. The scheme is presented with the simulation studies and experimentally verified with a 1.5-kW open-end winding IM drive. [ABSTRACT FROM AUTHOR]

This paper proposes operating a three-level neutral- point-clamped (NPC) inverter using a two-level pulsewidth-modulation method. This allows for the clamping diodes to be rated at a fraction of the main switches due to their low average current requirement. The use of a bootstrap charge pump as a low-cost method to obtain the isolated gate drive power supplies is extended for use with the NPC topology. Using this control method and circuits, an inverter based on high-volume, low-cost, low-voltage power MOSFETs is experimentally demonstrated as a possible economic alternative to an insulated-gate-bipolar-transistor-based drive for 120-Vrms-supplied systems. [ABSTRACT FROM AUTHOR]

The electric motorcycles have drawn much attention in recent years because of their portability and high flexibility, in which they became popular in many countries. However, balancing these devices in full-speed range, which is a valuable research within the countries heading to an aging society, has not been thoroughly researched. In this paper, a novel handlebar-free self-balancing electric motorcycle is put forward to cover this deficiency. By controlling the steering, the motorcycle can self balance by keeping its wheels swaying. Furthermore, three different steering modes of the motorcycle were discussed. A brief comparison about these modes was shown through several experiments. In order to achieve a full-speed range self-balancing motorcycle system, two different phase modes were applied in zero/low speed and normal/high speed, respectively. Finally, their stability was analyzed and proved. [ABSTRACT FROM PUBLISHER]

The main hypothesis proposed in this paper is that by controlling the harmonic and zero-sequence components of the current in nonsinusoidal permanent-magnet synchronous generators (PMGs), additional energy can be obtained, thereby increasing the machine power density without increasing the Joule effect losses. Two different strategies are proposed for three- and four-wire topologies; therefore, four different cases are analyzed. The strategies consist in controlling the PMG stator currents, following a function that depends on the waveform of the back electromotive force (EMF). The current function is obtained from the instantaneous reactive power theory. An experimental system was built to validate the proposal. Experimental results prove that it is possible to increase power in a tested PMG by 7% using the four-wire topology in comparison with the conventional block commutation and same losses. Higher power gain can be obtained for machines with almost rectangular-shaped EMF waveforms. [ABSTRACT FROM PUBLISHER]

The advancement of portable and implantable electronic devices has driven active research into wireless power transfer (WPT) methods. Current commercial WPT techniques using coil coupling have limitations, such as range, frequency, safety, line of sight, orientation, and concurrency. This paper presents a system utilizing oscillating magnets to extract power from a low-level ac magnetic field. This system enables the simultaneous powering of multiple low-power devices in an environment that meets human safety requirements. Compared with conventional WPT techniques, such as RF or acoustic power transfer, the proposed system transfers stable power to electronic nodes placed anywhere within the magnetic field under low driving frequency. Theoretical power calculations and experimental demonstrations are presented to prove the concepts and quantify performance. A custom three-dimensional printed millimeter-size oscillator loaded with two 8 \textmm^3 cubic permanent magnets is employed as the energy receiver to experimentally validate the proposed system. Measurements show that the raw ac electrical power and rectified dc power received by the oscillator achieve 269 and 135 \mu \textW, respectively, under 400 \mu\textT excitation magnetic field amplitude at 355 \textHz. [ABSTRACT FROM PUBLISHER]

The main objective of this paper is to examine the operation of a fundamental buck-based three-phase single-stage ac–dc full-bridge converter. In this paper, the operation of this fundamental converter is explained and analyzed, and a procedure for the design of its key components is derived and demonstrated with an example. The performance and characteristics of the converter are shown with experimental results that have been obtained from a prototype, and general concluding remarks comparing buck-based and boost-based three-phase single-stage ac–dc full-bridge converters are made. [ABSTRACT FROM PUBLISHER]

Droop control strategy is widely applied in ac microgrid to realize the seamless mode transition and achieve average power sharing among different inverters. However, there is a lack of analysis about the operation performance of droop control strategy in grid-connected mode. In this paper, grid fluctuation and control accuracy of reactive power are illustrated to be the main influence factors for power flow control according to the small-signal model. The feedforward of grid frequency and voltage magnitude is proposed to mitigate the impacts of grid fluctuation on power flow control. Since the feedforward items are achieved through the synchronous reference frame phase-locked loop with the input of filter capacitor voltage, extra sensors for grid voltage are avoided. Moreover, voltage magnitude control is introduced to enhance the control accuracy of reactive power flow. In addition, modified droop control loops are also proposed to improve the system stability. With the implementation of the proposed control scheme, improved power flow control and enhanced system stability are achieved with the feature of seamless mode transition maintained. Finally, the major contribution of this paper is verified by a laboratory prototype. [ABSTRACT FROM PUBLISHER]

This paper describes the development of a 50-kV 100-kW cathode power supply (CPS) for the operation of a 30-kW 95-GHz gyrotron. For stable operation of the gyrotron, the requirements of CPS include low output voltage ripple and low arc energy less than 1% and 10 J, respectively. Depending on required specifications, a three-phase series-parallel resonant converter (SPRC) is proposed for designing CPS. In addition to high-efficiency performance of SPRC, three-phase operation provides the reduction of the output voltage ripple through a minimized output filter component that is closely related to the arc energy. For allowing symmetrical resonant current from three-phase resonant inverter, the high-voltage transformers are configured as star connection with floated neutral node. This facilitates balanced voltage on each secondary winding. In addition, distinctive design of the high-voltage rectifier is introduced, taking into consideration the effective series stacking of diodes by means of the parallel resonant capacitor. In particular, the implementation of the high-voltage part including transformer and rectifier is presented in detail. For providing high power density and high reliability, effective methods for winding the high-voltage transformer and stacking rectifier diodes are discussed. Finally, the developed CPS achieves 95.5% of maximum efficiency, 0.92 of maximum power factor, 500 W/liter of power density, 0.6% of output voltage ripple, with 8.3-J arc energy. [ABSTRACT FROM AUTHOR]

This paper proposes a novel current link topology with a diode rectifier and magnetic energy recovery switch (MERS) using a current source inverter for offshore-wind-farm application. Despite the use of a diode rectifier, the proposed topology is capable of regulating individual turbine torque partially. Because offshore wind condition is more stable and has less turbulence intensity (typically 0.08) than that of onshore wind, the individual full-range controllability realized typically by pulse-controlled converters is not necessary. Instead of them, the proposed scheme, a diode rectifier with MERS, has only partial controllability of the individual generator torque which is estimated to be sufficient to achieve the maximum power point tracking operation for offshore-wind-farm application. The proposed topology is aiming to be applicable for offshore wind farms where maintenance reduction is conclusively a critical issue because of the inaccessibility. In this paper, experimental results represent the effectiveness of the topology. Moreover, a new control strategy for offshore wind farms with the proposed topology is also proposed. [ABSTRACT FROM PUBLISHER]

This paper presents a novel power supply of online condition monitoring systems for power transmission lines. The proposed power supply obtains energy from the magnetic field induced by transmission-line currents using a specially designed Rogowski coil. The design details of the power supply circuit including the unit for overvoltage and impulse line current protection are given in this paper. The impact to the power supply's reliability caused by abnormal high transmission-line currents is also addressed. Experimental tests, including the short-circuit and impulse-current tests, have been conducted on the power supply to verify its performance under different operating conditions. Test results show that the power supply is capable of providing stable outputs with no saturation and low heat generation for the entire range of line conducting currents and can sustain severe conditions such as abnormal impulse currents. [ABSTRACT FROM AUTHOR]

This paper proposes a model for the static power loss in photovoltaic (PV) panels due to switching-frequency ripple. Small-signal modeling is used to determine the amplitude of the voltage ripple that is imposed on the PY panel, and a closed-form expression is developed for the output power. The expression is shown to be more accurate than the power loss that was predicted by small-signal modeling alone, resulting in a median error of 0.8%. The model presented allows dc-dc converter designers to more precisely choose the input filter components that are critical during times of low insolation. [ABSTRACT FROM AUTHOR]

This paper presents power-control strategies of a grid-connected hybrid generation system with versatile power transfer. The hybrid system is the combination of photovoltaic (PV) array, wind turbine, and battery storage via a common dc bus. Versatile power transfer was defined as multimodes of operation, including normal operation without use of battery, power dispatching, and power averaging, which enables grid- or user-friendly operation. A supervisory control regulates power generation of the individual components so as to enable the hybrid system to operate in the proposed modes of operation. The concept and principle of the hybrid system and its control were described. A simple technique using a low-pass filter was introduced for power averaging. A modified hysteresis-control strategy was applied in the battery converter. Modeling and simulations were based on an electromagnetic-transient-analysis program. A 30-kW hybrid inverter and its control system were developed. The simulation and experimental results were presented to evaluate the dynamic performance of the hybrid system under the proposed modes of operation. [ABSTRACT FROM AUTHOR]

This paper describes a simple dc-dc step-up converter topology for switch-mode dc power supplies. The proposed configuration is well suited for high-power applications with battery supply. In the automotive framework, the push-pull architecture is the most widespread. However, as power increases, the use of a full-bridge architecture is mandatory. This paper presents a full-bridge architecture where the traditional single-phase transformer is replaced by a three-phase transformer. A prototype was realized and tested for the power supply of automotive devices. In this environment, one of the most important requirements is the ability to provide a burst of power during short-duration events, together with high-efficiency and high-quality output voltage. The latter constraints can be achieved by only using closed-loop switch-mode dc-dc converters at high switching frequency, thus reducing converter efficiency and creating electromagnetic- compatibility (EMC) problems. In this paper, the aforementioned issues were tackled relying on an open-loop topology. Open-loop converters are feasible if the output resistance of the converter is as low as possible, and a possible solution is the minimization of power losses. The solution is the use of a three-phase transformer with a delta-wye connection within a full-bridge converter topology. The configuration will be referred to as 3boost power supply. The three-phase transformer replaces the common single-phase transformer, and it is driven by a three-phase full-bridge inverter operating in six-step modulation. At secondary, a three-phase full wave diode rectifier is used to obtain the output dc voltage level. Therefore, a unitary transformer utilization factor is achieved. A simple theoretical comparison between the three types of converters—push-pull, conventional full bridge, and 3boost is shown. A low-power version of the converter was realized. Experiments confirm that this topology allows to achieve a high efficiency, a lower ripple factor, and a good EMC behavior. [ABSTRACT FROM AUTHOR]

This paper concentrates on two critical aspects to improve the performance of maximum power point tracking (MPPT). One improvement is to accurately locate the position of the maximum power point (MPP) by using the centered differentiation. Another effort is to reduce the oscillation around the MPP in steady state by controlling active perturbations. This paper also adopts the method of steepest descent for MPPT, which shows faster dynamic response and smoother steady state than the method of hill climbing. Comprehensive experimental evaluations have successfully illustrated the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a numerical analysis for the Class DE inverter with eliminated driving pulses. The harmonics, low-frequency components, and power conversion efficiency are calculated and shown. The Class DE inverter is one of the high-frequency high-efficiency resonant power sources that has the hybrid features of Class D and Class E circuits. To regulate the output power while maintaining high efficiency, various methods have been proposed. Thinned-out method is one of them, which regulates the output power by eliminating the driving pulses. The principle is quite simple and is seen suitable for digital control. However, the harmonics, low-frequency components, and discontinuous regulation have been pointed out. An aim of this paper is to clarify the characteristic of the Class DE inverter with thinned-out driving patterns. Basic models with three different Q-factors of 5, 10, and 20 are designed, built, tested, and analyzed. In a series of 16 cycles of switching pulses, 1-15 cycles are eliminated. The calculated waveforms show good agreement with circuit experiments. Various waveforms, harmonics, total harmonic distortion, low-frequency components, their total, and harmonics of the lowest frequency component are calculated and discussed. [ABSTRACT FROM AUTHOR]

Hardware-in-the-loop (HIL) testing is increasingly recognized as an effective approach in the design of power electronics controls. A high-performance real-time simulation environment is necessary to obtain high-fidelity results in HIL simulations. This paper presents the detailed implementation of a very-low-cost multisolver hard real-time simulation environment, namely the real-time extension of the virtual test bed (VTB-RT). VTB-RT is implemented completely from open-source software and off-the-shelf hardware. Using VTB-RT, this paper proposes an efficient real-time HIL testing approach for control designs in power electronics applications. VTB-RT enables the natural coupling between the simulation environment and the hardware under test and, thus, makes virtual power exchange in HIL simulation possible. For validation purposes, the proposed real-time HIL testing approach is applied in two well-known power electronics application examples, namely a boost converter and an H-bridge inverter with their respective control systems, representing a very-low-cost and a relatively advanced hardware setup, respectively. The consistency of the experimental results with the theoretical results proves the applicability of VTB-RT and the proposed testing approach. Finally, the most recent research progresses in VTB-RT are summarized. [ABSTRACT FROM AUTHOR]

Artificial intelligence (AI) techniques, particularly the neural networks, are recently having significant impact on power electronics and motor drives. Neural networks have created a new and advancing frontier in power electronics, which is already a complex and multidisciplinary technology that is going through dynamic evolution in the recent years. This paper gives a comprehensive introduction and perspective of neural network applications in the intelligent control and estimation for power electronics and motor drives area. The principal topologies of neural networks that are currently most relevant for applications in power electronics have been reviewed including the detailed description of their properties. Both feedforward and feedback or recurrent architectures have been covered in the description. The application examples that are discussed in this paper include nonlinear function generation, delayless filtering and waveform processing, feedback signal processing of vector drive, space vector PWM of two-level and multilevel inverters, adaptive flux vector estimation, and some of their combination for vector-controlled ac drive. Additional selected applications in the literature are included in the references. From the current trend of the technology, it appears that neural networks will find widespread applications in power electronics and motor drives in future. [ABSTRACT FROM AUTHOR]

Three-level converters are becoming a realistic alternative to the conventional converters in high-power wind-energy applications. In this paper, a complete analytical strategy to model a back-to-back three-level converter is described. This tool permits us to adapt the control strategy to the specific application. Moreover, the model of different loads can be incorporated to the overall model. Both control strategy and load models are included in the complete system model. The proposed model pays special attention to the unbalance in the capacitors' voltage of three-level converters, including the dynamics of the capacitors' voltage. In order to validate the model and the control strategy proposed in this paper, a 3-MW three-level back-to-back power converter used as a power conditioning system of a variable speed wind turbine has been simulated. Finally, the described strategy has been implemented in a 50-kVA scalable prototype as well, providing a satisfactory performance. [ABSTRACT FROM AUTHOR]

When the solar array is used as an input power source, the excellent operating point tracker is often employed to exploit more effectively the solar array as an electric power source and to obtain the maximum electric power at all times even when the light intensity and environmental temperature of the solar array are varied. Usually, the excellent operating point is determined by computing the electric power from the solar-array power supply with a microcomputer, digital signal processor, etc. However, such a method has the following problems: 1) complex control-circuit configuration; 2) high cost; and 3) low control speed. From this viewpoint, this paper proposes a new excellent operating point tracker of the solar-cell power supply system, in which inexpensive p-n junction diodes are used to generate the reference voltage of the operating point of the solar array. Using the proposed method, the high degree of the solar-array excellent point tracking performance can be obtained even when the light intensity and environmental temperature of the solar array are varied. Furthermore, this paper provides the operation principle, design-oriented analysis, etc., of the proposed solar-cell power supply system. [ABSTRACT FROM AUTHOR]

A novel single-stage series-resonant buck-boost inverter (SRBBI) is proposed in this paper. The main attribute of the novel inverter topology is the fact that it generates an ac output voltage larger or lower than the dc input one, depending on the instantaneous duty cycle. This property is not found in the classical voltage-source inverter, which produces an ac output instantaneous voltage which always lower than the dc input voltage. The state-space averaging approach is used to estimate and examine the steady-state and dynamic character of the new single-stage SRBBI. The principle of operation, theoretical analysis, and experimental results of the proposed inverter, rated 500 W and operating at 40 kHz, are provided in this paper to verify the performance of the SRBBI. [ABSTRACT FROM AUTHOR]

Single-phase single-stage power-factor-corrected converter topologies are reviewed in this paper. The topologies discussed in the paper are related to ac-dc and ac-ac converters that are classified on the basis of the frequency of the input ac source, the presence of a dc-link capacitor, and the type of control used (resonant or pulsewidth modulation). The general operating principles and strengths and weaknesses of the converters, which the authors have investigated over the last decade, are discussed in detail, and their suitability in practical applications is stated. Considering practical design constraints, it is possible to effectively employ many single-stage converter topologies in a wide range of applications. [ABSTRACT FROM AUTHOR]

A novel, single-phase soft-switched boost ac-dc rectifier that operates with power-factor correction is proposed in this paper. The rectifier is a modified boost voltage-doubler converter well suited for low-line-input applications. It operates with fewer conduction losses and half the switch voltage stresses found in a standard boost converter. Soft switching in the converter is achieved using a zero-current-switching quasi-resonant technique. In the paper, the converter and its modes of operation are discussed and analyzed. The method of control is explained, and a design procedure is derived and then demonstrated with an example. The feasibility of the converter is shown with experimental results obtained from a prototype. [ABSTRACT FROM AUTHOR]

This paper considers the analysis and design of a double-pinion-type electric power assist steering (EPAS) control system. A simplified model of the augmented steering assembly..electric motor system is developed using Lagrangian dynamics, and an optimal controller structure for the model is proposed. Three main advances to the state of the art are presented in this paper. First, a state-space design model is used rather than an input-output model. A state-space formulation for a system model that incorporates motor electrical dynamics is obtained with the assist motor angular position as the output. Second, linear quadratic regulator (LQR) and Kalman filter techniques are employed to arrive at an optimal controller for the EPAS system. The selection of weighting coefficients for the LQR cost function is discussed. Finally, the authors present a control strategy that eliminates the steering column torque sensor, a critical component in existing EPAS controller designs. The proposed control strategy presents an opportunity to improve EPAS system performance and also reduce system cost and complexity. [ABSTRACT FROM AUTHOR]

This paper is concerned with the maximum power tracking of a pneumatically driven electric generator in a standalone small-scale compressed air energy storage system. In this system, an air motor is used to drive a permanent-magnet direct-current generator, whose output is controlled by a buck converter supplying power to a resistive load. The output power of the converter is controlled such that the air motor operates at a speed corresponding to the maximum power. A maximum power point (MPP) tracking controller employs a hybrid perturb and observe method. The rate of change of the converter's output power with respect to its duty cycle and the change of the power and the duty cycle are used to correct the search direction under transient input power fluctuations. Small speed step changes are used in the vicinity of the MPP to improve the accuracy of the search algorithm. However, relatively coarse speed step changes are used when the operating point is far from the MPP to improve the dynamic response of the controller and to increase its speed of convergence. The analysis and design of the controller are based on a small injected-absorbed current signal model of the power converter. The controller is experimentally implemented using a real-time digital signal processor system. Test results are presented to validate the proposed design and to demonstrate its capabilities. [ABSTRACT FROM PUBLISHER]

This paper presents a detailed modeling and analysis of an inductive power transfer (IPT) system with a passive matrix power repeater. A high-order mathematical model is established to characterize the output power by taking all the mutual inductances among the primary, secondary, and the unit cells of matrix power repeaters into considerations. The model is used to analyze the relationship between the output power and the operating frequency of an IPT system with a 3 × 3 matrix power repeater. The study shows the optimal operating frequencies corresponding to maximum and minimum power transfer exist owing to the interactions among the magnetic fields generated by the primary current and induced currents of the unit cells of the matrix power repeater. The theoretical optimal frequencies for obtaining the maximum and minimum output power are determined by numerical analysis based on the proposed model, and they are verified by circuit simulation and experimental study within an error of 2%. The results are useful for power flow controller design with enhanced and reduced power regulation range. [ABSTRACT FROM AUTHOR]

This paper deals with the protection of critical loads from voltage-related power quality issues using a dynamic voltage restorer (DVR). A generalized control algorithm based on instantaneous space phasor and dual $P$ - $Q$ theory has been proposed to generate the instantaneous reference voltages to compensate the load voltages with direct power flow control. The proposed algorithm adapts energy-optimized series voltage compensation, which results in a reduction of energy storage requirement. The proposed DVR control scheme can support the load from voltage-related power quality issues irrespective of the load current profile. Each leg of the three-phase three-leg split capacitor inverter is used to inject series compensation voltage in respective phases of the system. Model-based computer simulation studies and real-time experimental results validate the effectiveness of the proposed control algorithm. [ABSTRACT FROM AUTHOR]

The challenging issue of “human–machine copilot” opens up a new frontier to enhancing driving safety. However, driver–machine conflicts and uncertain driver/external disturbances are significant problems in cooperative steering systems, which degrade the system's path-tracking ability and reduce driving safety. This paper proposes a novel stochastic game-based shared control framework to model the steering torque interaction between the driver and the intelligent electric power steering (IEPS) system. A six-order driver–vehicle dynamic system, including driver/external uncertainty, is established for path-tracking. Then, the affine linear-quadratic-based path-tracking problem is proposed to model the maneuvers of the driver and IEPS. Particularly, the feedback Nash and Stackelberg frameworks to the affine-quadratic problem are derived by stochastic dynamic programming. Two cases of copilot lane change driving scenarios are studied via computer simulation. The intrinsic relation between the stochastic Nash and Stackelberg strategies is investigated based on the results. And the steering-in-the-loop experiment reveals the potential of the proposed shared control framework in handling driver–IEPS conflicts and uncertain driver/external turbulence. Finally, the copiloting experiments with a human driver further demonstrate the rationality of the game-based pattern between both the agents. [ABSTRACT FROM AUTHOR]

Capacitorless (CL) low-dropout regulators (LDO) have gained significant research interest for point-of-load voltage regulation without off-chip capacitors. While analog CL-LDOs can deliver superior power supply rejection (PSR), digital CL-LDOs are more scalable and efficient. To achieve the advantages of both types, this paper presents a digital CL-LDO with an analog PSR enhancer, delivering strong PSR without compromising scalability and efficiency. Load regulation is performed by an asynchronous digital feedback controller for fast transient response and scalable load drivability. PSR is achieved by a load-insensitive wide-bandwidth analog controller. A prototype chip of the analog-assisted digital CL-LDO is fabricated in a 130-nm CMOS process with an active area of 0.0645 mm2 , supporting load current up to 50 mA at nominal 1-V input and 0.8-V output. The measured PSR is better than –20 dB for frequencies up to 10 MHz, and the measured current efficiency peaks at 99.3%, with average current efficiency of 96.7% across 50× load range. The measured transient response to a full load step, with two values of load capacitance (100 pF and 10 nF), demonstrates the LDO's stable operation over a wide range of load resistance and capacitance. [ABSTRACT FROM AUTHOR]

This paper proposes a novel FPGA-based matrix-inversion technique that is specifically tailored and optimized for real-time electromagnetic transients simulation of power electronic converters with high switching frequency. This is the first reported solution that is capable of solving the real-time equations related to using ideal switch model and the associated circuitry in very small time-steps (e.g., an average of 36 ns in a three-phase back-to-back converter case study), without requiring large amount of memory, being limited to small number of switches, adding parasitic elements, or depending on a priori knowledge of the circuit operation or switching strategy. The accuracy of the proposed real-time simulator is verified against the results from experimental measurements. [ABSTRACT FROM AUTHOR]

In microgrids, distributed load sharing plays an important role in maintaining the supply–demand balance of power. Because false data injection (FDI) is one of the crucial threats faced by future microgrids, the study of the impact of FDI on distributed load sharing is both of theoretical merit and practical value. In this paper, we consider the distributed load sharing problem of the microgrids operating in autonomous mode under FDI. Each bus is assumed to be equipped with an agent. Under a well-developed distributed load sharing protocol based on multiagent systems, we first construct an FDI attack model, where the attacker is capable of injecting false data into the bus agents. Then, a utilization level is introduced for coordinating generators, and its variation is evaluated in the presence of FDI attacks with given injection strategies. The stable region of the microgrid is defined, and conditions are given to determine stability. Finally, theoretical results are validated on the Canadian urban distribution system. [ABSTRACT FROM AUTHOR]

Multilevel converter topologies are widely used in applications of wide-power range. The T-type topology, which is one of many three-level topologies, has an advantage in terms of efficiency compared to the neutral-point-clamped (NPC) type. In applications using the T-type topology, interest in reliability has been increased recently. Therefore, the open-switch fault detection method and tolerance control for T-type rectifiers, which are different from those of T-type inverters, are necessary to improve the reliability of applications. When the open-switch fault of switches connected to a neutral point occurs, an NPC-type rectifier cannot restore distorted input currents; however, a T-type rectifier is able to eliminate input current distortion completely. In this paper, an open-switch fault detection method is proposed and can find a position of the open-switch fault. Moreover, two tolerance controls based on space vector modulation are proposed and their characteristics are analyzed. The effectiveness and performance of the proposed open-switch fault detection method and two tolerance controls are verified by simulations and experiments. [ABSTRACT FROM PUBLISHER]

This paper introduces an innovative contactless energy transfer system for power supplying rotatable parts of automatic machineries as a robust alternative to sliding contacts. The design procedure of the key system devices, such as the dc/ac converter and the rotary transformer with its windings, is discussed. Different configurations in terms of switching network, number of turns, wire, and compensation are discussed with respect to their impact on the system efficiency and power factor. A thermal model to account for the core temperature is also introduced. Two setups, operating at 50 kHz and able to transfer up to 1.3 kW in a contactless fashion, are realized and tested to supply sealing roller resistors of automatic machineries. The system prototypes are then experimentally tested to validate the analytical models and the finite element simulations of the entire wireless power transfer link. Trade-offs emerge from the setups, in particular concerning efficiency, power factor, and electro-magnetic compatibility. As a consequence, we discuss the choice of the optimal configuration depending on the final application. [ABSTRACT FROM PUBLISHER]

An input-series output-parallel (ISOP) system, in which multiple converter modules are connected in series at the input sides and parallel at the output side, is very suitable for high input-voltage, low output-voltage, and high output-current applications. Input-voltage sharing (IVS) and output-current sharing of the constituent modules among the ISOP system must be ensured. The existing IVS control strategies have drawbacks of lower reliability and lower modularity. In this paper, we propose a wireless IVS control strategy for ISOP systems based on positive output-voltage gradient method, which can effectively improve the reliability and modularity of ISOP systems. First, the operation principle of the proposed control strategy is introduced, and the IVS performance and output-voltage regulation characteristics of ISOP systems are analyzed. The stability of the proposed control strategy is also explored. A three-module ISOP system prototype is fabricated and tested in the laboratory, and the experimental results verify the effectiveness of the proposed control strategy. [ABSTRACT FROM PUBLISHER]