Search

The operation of traditional rectifiers such as half-wave and bridge rectifiers in wireless power transfer applications may be inefficient and can reduce the amount of power that is delivered to a load. An alternative is to use Class E resonant rectifiers that are known to operate efficiently at high resonant frequencies and at large input voltages. Class E rectifiers have a near sinusoidal input current which leads to an improved overall system performance and increased efficiency, especially that of the transmitting coil driver. This paper is the first to investigate the use of Class E resonant rectifiers in wireless power transfer systems based on resonant inductive coupling. A piecewise linear state-space representation is used to model the Class E rectifier including the rectifying diode's forward voltage drop, its ON resistance, and the equivalent series resistance of the resonant inductor. Power quality parameters, such as power factor and total harmonic distortion, are calculated for different loading conditions. Extensive experimental results based on a 10-W prototype are presented to confirm the performed analysis and the efficient operation of the rectifier. An impressive operating efficiency of 94.43% has been achieved at a resonant frequency of 800 kHz.

In light of the rapid growth of dc loads, ICPS created a small team to outline design considerations for dc distribution and controls. Broad interest in the subject brought in a large group who provided substantial support for the Team. The report begins with a brief background followed by discussion of design considerations that affect ICPS and IAS. The key part of the report is Part IV, which outlines in detail a path forward for ICPS and for IAS. Appendix A outlines an approach toward developing dc standards or recommended practices for design of industrial and commercial power systems. Appendix B lists some of the organizations and individuals that are working on related dc issues at present.

This paper presents a dynamic analysis and the control design for a singe-phase full bridge recti¿er with a LCL ¿lter. The control algorithm is based on the sliding mode control techniques that provides good tracking performances and robustness against parameter variations. The control design also considers the connection to a non ideal power network with a grid impedance as well as higher harmonics components in the voltage. The control law has been tested in numerical simulations with satisfactory results (also in the case of non ideal power grid).

Use of modern electric vehicles and their effective integration into power grids depends on the technologies applied around distribution substations. Distribution substations equipped with energy storing and V2G capability enable peak load shaving and demand response, which will reduce the need to make new investments into building new power sources or power grids to meet peak demand. This paper presents a distribution substation topology for utilizing electric vehicles as energy resource units for peak shaving of utility network loads. The topology allows bidirectional energy exchange among electric vehicles, battery pack energy storage devices and utility networks. The substation acts as a service provider in a microgrid. Functions of a microgrid application were simulated with MATLAB. The evaluation of the results has shown that electric vehicles can be effectively utilized for peak shaving of utility network loads. The results of the modelling and simulation were used for the development of a microgrid prototype. Assessment of capacities of electric vehicles showed that electric vehicles can provide short term support for the utility network.

In this paper the grid current higher harmonic compensation method for two level AC-DC converters in sustainable AC grid is described. The algorithm is based on Direct Power Control with Space Vector Modulator (DPC-SVM), which was extended by additional Higher Harmonics Compensation (HHC) module. The HHC block is composed of several resonant filters tuned to appropriate frequencies. Both, symmetrical and asymmetrical types of grid currents distortions are analyzed. Operation of the HHC module in stationary αβ coordinates and rotating dq coordinates is discussed. Selected waveforms illustrating operation of the developed algorithm are presented. It is shown that in dq coordinates asymmetrical voltage distortions needs additional effort for its compensation in comparison to symmetrical higher harmonics. The subject is important because in practice asymmetrical higher harmonics usually can appear when one phase nonlinear load is connected to the grid. Even within such conditions the grid connected AC-DC converter (GCC) should provide sinusoidal-like current. This assumption provides the reduction of negative impact of the GCC in power quality in Point of Common Coupling (PCC) in sustainable AC grid.

This paper focuses on modeling and simulation of controllable Photovoltaic Battery Power System (PV BPS) interconnected to the electrical utility. After elaboration of modeling principles for different components appearing in the system, simulations of two types of PV plants connected to one branch of distribution network have been carried out. First one is connected through a three-phase inverter with battery string connected to a DC-link and the second string is connected to the grid in single phase configuration. In this proposed configuration unpredictable variations of irradiation and temperature are taken into an account and PV BPS is able to inject the power to the grid in regulated manner using developed power control algorithm.

The present article studies the converter, which is based on dual half-bridge topology with common neutral wire that is not commutating during converter’s operation. The current sensorless control algorithm has been obtained analytically for rectification, grid-tied and stand-alone inverter modes, which average value tracks reference current signal with constant switching frequency. Two control functions for inductor’s discontinuous and continuous current modes have been defined for each of operation modes, and sensorless transition between two modes has been stated. The results of simulation in the PSIM software approved the analytical model, keeping the average inductor’s current to follow the reference value in inductor’s discontinuous and continuous conduction modes.

This paper deals with the design of a fault tolerant digital control of high power, parallelable frequency converters for harbor application. With the aim to yield a high degree of system availability the control algorithm must be able to automatically switch from parallel to single mode operation in case of fault. Scalability is a further key feature of the proposed control strategy: in order to increase the output power rating, the control strategy can parallel more than two converters increasing, in turn, the availability of the whole system as well. An inclusive set of MATLAB simulations shows that the proposed control algorithm makes the whole power system complying with the specifications in terms of THD, power efficiency and dynamic response. A full set of measurements, performed on a scaled converter prototype, confirmed the simulation results.

In this paper, we present for the first time a novel optimization procedure which allows to maximize the efficiency of RF-DC energy harvester converters, taking into account the contributions of the matching network. Thanks to this procedure, we have designed and realized a CMOS RF-DC converter operating in a very wide range of input power −14÷+1dBm with a peak efficiency of 45% The RF-DC converter provides a constant output voltage ∼2V in the whole input power range thanks to a smart voltage regulator integrated with the converter.

Conditioning of network impedance by insertion of a virtual inductance as an inherent feature of the converter control system has the potential to extend the range of stable operation of the overall system. This paper presents a scenario in which such potential is explored and its range of application is identified. It shows first that implementation of a virtual inductance is naturally suited for combination with Virtual Flux-based control systems, and that it can be extended to the more general case of a virtual reactance. The paper then presents the structure of a control system for operation under unbalanced conditions, where the virtual inductance directly influences the current reference calculation. Compared with the standard approach of unity power factor control of grid integrated converters, the suggested technique allows for improving the stability range of converters operating in high-impedance grids, and for remote point control of reactive power or power factor.

Modern power distribution systems experience a large-scale integration of Converter-Interfaced Distributed Energy Resources (CIDERs). As acknowledged by recent literature, the interaction of individual CIDER components and different CIDERs through the grid can lead to undesirable amplification of harmonic frequencies and, ultimately, compromise the distribution system stability. In this context, the interaction of the DC and AC sides of CIDERs has been shown to have a significant impact. In order to analyze and support the mitigation of such phenomena, the authors of this paper recently proposed a Harmonic Power-Flow (HPF) framework for polyphase grids with a high share of CIDERs. The framework considers the coupling between harmonics, but ignores the DC-side response of the CIDERs. Modelling the DC side and the AC/DC converter introduces a nonlinearity into the CIDER model that needs to be approximated for the numerical solution of the HPF. This paper extends the CIDER model and HPF framework to address this aspect, whose inclusion is non-trivial. The extended HPF method is applied to a modified version of the CIGRÉ low-voltage benchmark microgrid. The results are compared to (i) timedomain simulations with Simulink, (ii) the predecessor of the extended HPF which neglects the DC side, and (iii) a classical decoupled HPF.

This paper presents a dynamic analysis and the control design for a three-phase three-wire unity power factor rectifier with a LCL filter. The control algorithm is based on the sliding mode control techniques that provides good tracking performance and robustness with respect to parameter variations, and a PI controller to regulate the DC voltage. The sliding control design uses a decoupling matrix to solve the algebraic constraint on the grid currents. The control law has been tested in numerical simulations with satisfactory results. © 2014 IEEE.

The present paper addresses the practical implementation in a test bench of different control strategies for the start-up of a varspeed group in pump mode. In varspeed groups using a double-fed induction machine supplied by back to back voltage source inverters (VSI), the possibility exists of using the rotor side VSI to start up the group. The current paper focuses on the start-up strategy and its implementation in a test bench of 3.3 kVA. After presenting the hardware composing the test bench, two different start-up strategies are detailed, which are the field oriented control and critical torque. Those two strategies are then implemented in practice, tested, measured and compared.

This paper explains the working principles, supported by simulation results, of a new converter topology intended for HVDC applications, called the alternate arm converter (AAC). It is a hybrid between the modular multilevel converter, because of the presence of H-bridge cells, and the two-level converter, in the form of director switches in each arm. This converter is able to generate a multilevel ac voltage and since its stacks of cells consist of H-bridge cells instead of half-bridge cells, they are able to generate higher ac voltage than the dc terminal voltage. This allows the AAC to operate at an optimal point, called the “sweet spot,” where the ac and dc energy flows equal. The director switches in the AAC are responsible for alternating the conduction period of each arm, leading to a significant reduction in the number of cells in the stacks. Furthermore, the AAC can keep control of the current in the phase reactor even in case of a dc-side fault and support the ac grid, through a STATCOM mode. Simulation results and loss calculations are presented in this paper in order to support the claimed features of the AAC.

In low power distributed generation systems low cost together with the energy quality requirements are a key element. It is known that quality of voltage waveforms generated from multilevel converters is better in comparison with those from two-level. Due to advancements in power electronics and microcontrollers, multilevel converters are being built with the use of integrated power modules thus this type of converters are getting more compact in size. This paper investigates performance of a derivation from the most popular multilevel topology - a neutral point clamped converter (NPC). Applying the idea for simplifying the topology by reducing the number of switches (what came from drives) this NPC converter is capable of bidirectional AC/DC/AC operation. For the AC/DC part two schemes are tested: Direct Torque Control Space Vector Modulated and Field Oriented Control but for the DC/AC part a control scheme utilizing the proportional-resonant controller was chosen. Laboratory setup was based on a permanent magnet synchronous generator with control and acquisition completed with the help of dSpace 1005 control box. Experimental verification shows that system operates properly.