Showing papers in "IEEE Transactions on Industrial Electronics in 2010"
TL;DR: This paper first presents a brief overview of well-established multilevel converters strongly oriented to their current state in industrial applications to then center the discussion on the new converters that have made their way into the industry.
Abstract: Multilevel converters have been under research and development for more than three decades and have found successful industrial application. However, this is still a technology under development, and many new contributions and new commercial topologies have been reported in the last few years. The aim of this paper is to group and review these recent contributions, in order to establish the current state of the art and trends of the technology, to provide readers with a comprehensive and insightful review of where multilevel converter technology stands and is heading. This paper first presents a brief overview of well-established multilevel converters strongly oriented to their current state in industrial applications to then center the discussion on the new converters that have made their way into the industry. In addition, new promising topologies are discussed. Recent advances made in modulation and control of multilevel converters are also addressed. A great part of this paper is devoted to show nontraditional applications powered by multilevel converters and how multilevel converters are becoming an enabling technology in many industrial sectors. Finally, some future trends and challenges in the further development of this technology are discussed to motivate future contributions that address open problems and explore new possibilities.
3,415 citations
TL;DR: A survey of different topologies, control strategies and modulation techniques used by cascaded multilevel inverters in the medium-voltage inverter market is presented.
Abstract: Cascaded multilevel inverters synthesize a medium-voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. Due to these features, the cascaded multilevel inverter has been recognized as an important alternative in the medium-voltage inverter market. This paper presents a survey of different topologies, control strategies and modulation techniques used by these inverters. Regenerative and advanced topologies are also discussed. Applications where the mentioned features play a key role are shown. Finally, future developments are addressed.
2,111 citations
TL;DR: The basic operation and the most used modulation and control techniques developed to date of neutral-point-clamped inverters are presented and some technological problems such as capacitor balance and losses are presented.
Abstract: Neutral-point-clamped (NPC) inverters are the most widely used topology of multilevel inverters in high-power applications (several megawatts). This paper presents in a very simple way the basic operation and the most used modulation and control techniques developed to date. Special attention is paid to the loss distribution in semiconductors, and an active NPC inverter is presented to overcome this problem. This paper discusses the main fields of application and presents some technological problems such as capacitor balance and losses.
1,556 citations
TL;DR: A comprehensive experimental study on the statistical characterization of the wireless channel in different electric-power-system environments, including a 500-kV substation, an industrial power control room, and an underground network transformer vault is presented.
Abstract: The collaborative and low-cost nature of wireless sensor networks (WSNs) brings significant advantages over traditional communication technologies used in today's electric power systems. Recently, WSNs have been widely recognized as a promising technology that can enhance various aspects of today's electric power systems, including generation, delivery, and utilization, making them a vital component of the next-generation electric power system, the smart grid. However, harsh and complex electric-power-system environments pose great challenges in the reliability of WSN communications in smart-grid applications. This paper starts with an overview of the application of WSNs for electric power systems along with their opportunities and challenges and opens up future work in many unexploited research areas in diverse smart-grid applications. Then, it presents a comprehensive experimental study on the statistical characterization of the wireless channel in different electric-power-system environments, including a 500-kV substation, an industrial power control room, and an underground network transformer vault. Field tests have been performed on IEEE 802.15.4-compliant wireless sensor nodes in real-world power delivery and distribution systems to measure background noise, channel characteristics, and attenuation in the 2.4-GHz frequency band. Overall, the empirical measurements and experimental results provide valuable insights about IEEE 802.15.4-compliant sensor network platforms and guide design decisions and tradeoffs for WSN-based smart-grid applications.
1,255 citations
TL;DR: An inverter configuration based on three-level building blocks to generate five-level voltage waveforms is suggested and it is shown that such an inverter may be operated at a very low switching frequency to achieve minimum on-state and dynamic device losses for highly efficient MV drive applications while maintaining low harmonic distortion.
Abstract: This paper gives an overview of medium-voltage (MV) multilevel converters with a focus on achieving minimum harmonic distortion and high efficiency at low switching frequency operation. Increasing the power rating by minimizing switching frequency while still maintaining reasonable power quality is an important requirement and a persistent challenge for the industry. Existing solutions are discussed and analyzed based on their topologies, limitations, and control techniques. As a preferred option for future research and application, an inverter configuration based on three-level building blocks to generate five-level voltage waveforms is suggested. This paper shows that such an inverter may be operated at a very low switching frequency to achieve minimum on-state and dynamic device losses for highly efficient MV drive applications while maintaining low harmonic distortion.
1,150 citations
TL;DR: This paper will cover the theory and design of FSCW synchronous PM machines, achieving high-power density, flux-weakening capability, comparison of single- versus double-layer windings, fault-tolerance rotor losses, parasitic effects, compared of interior versus surface PM machine, and various types of machines.
Abstract: Fractional-slot concentrated-winding (FSCW) synchronous permanent magnet (PM) machines have been gaining interest over the last few years. This is mainly due to the several advantages that this type of windings provides. These include high-power density, high efficiency, short end turns, high slot fill factor particularly when coupled with segmented stator structures, low cogging torque, flux-weakening capability, and fault tolerance. This paper is going to provide a thorough analysis of FSCW synchronous PM machines in terms of opportunities and challenges. This paper will cover the theory and design of FSCW synchronous PM machines, achieving high-power density, flux-weakening capability, comparison of single- versus double-layer windings, fault-tolerance rotor losses, parasitic effects, comparison of interior versus surface PM machines, and various types of machines. This paper will also provide a summary of the commercial applications that involve FSCW synchronous PM machines.
1,126 citations
TL;DR: This paper presents a review of ESSs for transport and grid applications, covering several aspects as the storage technology, the main applications, and the power converters used to operate some of the energy storage technologies.
Abstract: Energy storage systems (ESSs) are enabling technologies for well-established and new applications such as power peak shaving, electric vehicles, integration of renewable energies, etc. This paper presents a review of ESSs for transport and grid applications, covering several aspects as the storage technology, the main applications, and the power converters used to operate some of the energy storage technologies. Special attention is given to the different applications, providing a deep description of the system and addressing the most suitable storage technology. The main objective of this paper is to introduce the subject and to give an updated reference to nonspecialist, academic, and engineers in the field of power electronics.
1,115 citations
TL;DR: The NCS and its different forms are introduced and discussed, and different fields and research arenas such as networking technology, network delay, network resource allocation, scheduling, network security in real-time NCSs, integration of components on a network, fault tolerance, etc.
Abstract: Networked control systems (NCSs) have been one of the main research focuses in academia as well as in industry for many decades and have become a multidisciplinary area. With these growing research trends, it is important to consolidate the latest knowledge and information to keep up with the research needs. In this paper, the NCS and its different forms are introduced and discussed. The beginning of this paper discusses the history and evolution of NCSs. The next part of this paper focuses on different fields and research arenas such as networking technology, network delay, network resource allocation, scheduling, network security in real-time NCSs, integration of components on a network, fault tolerance, etc. A brief literature survey and possible future direction concerning each topic is included.
1,053 citations
TL;DR: The operation of modular multilevel converter is described, an emerging and highly attractive topology for medium- and high-voltage applications and a new pulsewidth-modulation scheme for an arbitrary number of voltage levels is introduced and evaluated.
Abstract: This paper describes the operation of modular multilevel converter, an emerging and highly attractive topology for medium- and high-voltage applications. A new pulsewidth-modulation (PWM) scheme for an arbitrary number of voltage levels is introduced and evaluated. On the basis of this PWM scheme, the semiconductor losses are calculated, and the loss distribution is illustrated.
899 citations
TL;DR: This paper presents a method for modeling and estimation of the state of charge (SOC) of lithium-ion (Li-Ion) batteries using neural networks (NNs) and the extended Kalman filter (EKF).
Abstract: This paper presents a method for modeling and estimation of the state of charge (SOC) of lithium-ion (Li-Ion) batteries using neural networks (NNs) and the extended Kalman filter (EKF). The NN is trained offline using the data collected from the battery-charging process. This network finds the model needed in the state-space equations of the EKF, where the state variables are the battery terminal voltage at the previous sample and the SOC at the present sample. Furthermore, the covariance matrix for the process noise in the EKF is estimated adaptively. The proposed method is implemented on a Li-Ion battery to estimate online the actual SOC of the battery. Experimental results show a good estimation of the SOC and fast convergence of the EKF state variables.
654 citations
TL;DR: The latest progress in kinetic energy harvesting for wide applications ranging from implanted devices and wearable electronic devices to mobile electronics and self-powered wireless network nodes is presented.
Abstract: This paper presents the latest progress in kinetic energy harvesting for wide applications ranging from implanted devices and wearable electronic devices to mobile electronics and self-powered wireless network nodes. The advances in energy harvesters adopting piezoelectric and electromagnetic transduction mechanisms are presented. Piezoelectric generators convert mechanical strain on the active material to electric charge while electromagnetic generators make use of the relative motion between a conductor and a magnetic flux to induce charge in the conductor. The existent kinetic piezoelectric generators including human-powered and vibration-based devices are comprehensively addressed. In addition, the electromagnetic generators which include resonant, rotational, and ?hybrid? devices are reviewed. In the conclusion part of this paper, a comparison between the transduction methods and future application trends is given.
TL;DR: This paper will propose a single-phase transformerless inverter circuit being composed of the association of two step-down converters, which is possible to achieve a high level of efficiency and reliability.
Abstract: Driven by worldwide demand for renewable sources, the photovoltaic market saw in the last years a considerable amount of innovations regarding the construction and operation of inverters connected to the grid. One significant advance, among some that will be here discussed is, for example, the abolition of the galvanic isolation in inverters installed in Germany. There, transformerless topologies, like the H5 and Heric, can reach very high levels of efficiency and allow the best cost-benefit ratio for low-power grid-tied systems. This paper will follow this direction and propose a single-phase transformerless inverter circuit being composed of the association of two step-down converters. Each one modulates a half-wave of the output current, as the correct polarity of the connection to the grid is provided by low-frequency switches. Due to its straightforward design, reduced amount of semiconductors, and simple operation, it is possible to achieve a high level of efficiency and reliability. These and some other characteristics will be benchmarked against other existing circuits, being followed by a theoretical analysis on the properties of the proposed solution. The project of a laboratory prototype will be presented, along with a discussion about the obtained experimental results.
TL;DR: A model predictive current control algorithm that is suitable for multilevel converters and its application to a three-phase cascaded H-bridge inverter and experimental results validate the proposed control algorithm.
Abstract: This paper presents a model predictive current control algorithm that is suitable for multilevel converters and its application to a three-phase cascaded H-bridge inverter. This control method uses a discrete-time model of the system to predict the future value of the current for all voltage vectors, and selects the vector which minimizes a cost function. Due to the large number of voltage vectors available in a multilevel inverter, a large number of calculations are needed, making difficult the implementation of this control in a standard control platform. A modified control strategy that considerably reduces the amount of calculations without affecting the system's performance is proposed. Experimental results for five- and nine-level inverters validate the proposed control algorithm.
TL;DR: A new current feedback method for PR current control is proposed, where the weighted average value of the currents flowing through the two inductors of the LCL filter is used as the feedback to the current PR regulator.
Abstract: For a grid-connected converter with an LCL filter, the harmonic compensators of a proportional-resonant (PR) controller are usually limited to several low-order current harmonics due to system instability when the compensated frequency is out of the bandwidth of the system control loop. In this paper, a new current feedback method for PR current control is proposed. The weighted average value of the currents flowing through the two inductors of the LCL filter is used as the feedback to the current PR regulator. Consequently, the control system with the LCL filter is degraded from a third-order function to a first-order one. A large proportional control-loop gain can be chosen to obtain a wide control-loop bandwidth, and the system can be optimized easily for minimum current harmonic distortions, as well as system stability. The inverter system with the proposed controller is investigated and compared with those using traditional control methods. Experimental results on a 5-kW fuel-cell inverter are provided, and the new current control strategy has been verified.
TL;DR: A dimmable light-emitting diode (LED) driver with adaptive feedback control for low-power lighting applications and an improved pulsewidth modulation dimming technique is studied for regulating the LED current and brightness.
Abstract: This paper presents a dimmable light-emitting diode (LED) driver with adaptive feedback control for low-power lighting applications. An improved pulsewidth modulation dimming technique is studied for regulating the LED current and brightness. Under universal input voltage operation, high efficiency and high power factor can be achieved by a coupled inductor single-ended primary inductance converter power factor correction (PFC) converter with a simple commercial transition-mode PFC controller. The operation principles and design considerations of the studied LED driver are analyzed and discussed. A laboratory prototype is also designed and tested to verify the feasibility.
TL;DR: Methods to overcome the challenges of real-time simulation of wind systems, characterized by their complexity and high-frequency switching are discussed.
Abstract: Wind power generation studies of slow phenomena using a detailed model can be difficult to perform with a conventional offline simulation program. Due to the computational power and high-speed input and output, a real-time simulator is capable of conducting repetitive simulations of wind profiles in a short time with detailed models of critical components and allows testing of prototype controllers through hardware-in-the-loop (HIL). This paper discusses methods to overcome the challenges of real-time simulation of wind systems, characterized by their complexity and high-frequency switching. A hybrid flow-battery supercapacitor energy storage system (ESS), coupled in a wind turbine generator to smooth wind power, is studied by real-time HIL simulation. The prototype controller is embedded in one real-time simulator, while the rest of the system is implemented in another independent simulator. The simulation results of the detailed wind system model show that the hybrid ESS has a lower battery cost, higher battery longevity, and improved overall efficiency over its reference ESS.
TL;DR: A feedback linearization (FL)-based control law made implementable using an extended state observer (ESO) is proposed for the trajectory tracking control of a flexible-joint robotic system and the closed-loop stability of the system under the proposed observer-controller structure is established.
Abstract: In this paper, a feedback linearization (FL)-based control law made implementable using an extended state observer (ESO) is proposed for the trajectory tracking control of a flexible-joint robotic system. The FL-based controller cannot be implemented unless the full transformed state vector is available. The design also requires exact knowledge of the system model making the controller performance sensitive to uncertainties. To address these issues, an ESO is designed, which estimates the state vector, as well as the uncertainties in an integrated manner. The FL controller uses the states estimated by ESO, and the effect of uncertainties is compensated by augmenting the FL controller with the ESO-estimated uncertainties. The closed-loop stability of the system under the proposed observer-controller structure is established. The effectiveness of the ESO in the estimation of the states and uncertainties and the effectiveness of the FL + ESO controller in tracking are demonstrated through simulations. Lastly, the efficacy of the proposed approach is validated through experimentation on Quanser's flexible-joint module.
TL;DR: Simulation and experimental results demonstrate the effectiveness of the proposed method, which combines two recursive least square algorithm segments in real time with rich enough data from the machine to estimate all four machine parameters instead of a subset of these.
Abstract: This paper focuses on the benefits of adaptive control for permanent-magnet synchronous machines; a novel method of online parameter estimation for such machines has been developed. Two recursive least square algorithm segments, a fast and a slow one, are uniquely combined in real time with rich enough data from the machine to estimate all four machine parameters instead of a subset of these. Simulation and experimental results demonstrate the effectiveness of the proposed method.
TL;DR: The proposed single-phase H-bridge multilevel converter for PV systems governed by a new integrated fuzzy logic controller (FLC)/modulator offers improved performance over two-level inverters, particularly at low-medium power.
Abstract: Converters for photovoltaic (PV) systems usually consist of two stages: a dc/dc booster and a pulsewidth modulated (PWM) inverter. This cascade of converters presents efficiency issues, interactions between its stages, and problems with the maximum power point tracking. Therefore, only part of the produced electrical energy is utilized. In this paper, the authors propose a single-phase H-bridge multilevel converter for PV systems governed by a new integrated fuzzy logic controller (FLC)/modulator. The novelties of the proposed system are the use of a fully FLC (not requiring any optimal PWM switching-angle generator and proportional-integral controller) and the use of an H-bridge power-sharing algorithm. Most of the required signal processing is performed by a mixed-mode field-programmable gate array, resulting in a fully integrated System-on-Chip controller. The general architecture of the system and its main performance in a large spectrum of practical situations are presented and discussed. The proposed system offers improved performance over two-level inverters, particularly at low-medium power.
TL;DR: The number of gate driving circuits is reduced, which leads to the reduction of the size and power consumption in the driving circuits, and the total harmonic of the output waveform is also reduced.
Abstract: A novel multilevel inverter with a small number of switching devices is proposed. It consists of an H-bridge and an inverter which outputs multilevel voltage by switching the dc voltage sources in series and in parallel. The proposed inverter can output more numbers of voltage levels in the same number of switching devices by using this conversion. The number of gate driving circuits is reduced, which leads to the reduction of the size and power consumption in the driving circuits. The total harmonic of the output waveform is also reduced. The proposed inverter is driven by the hybrid modulation method. In this paper, the circuit configuration, theoretical operation, Fourier analysis, simulation results with MATLAB/SIMULINK, and experimental results are shown. The experimental results accorded with the simulation results.
TL;DR: The main reasons why the conventional method for converter analysis fails are described and the different steps required to predict the power losses more accurately are documents.
Abstract: An accurate power loss model for a high-efficiency dual active bridge converter, which provides a bidirectional electrical interface between a 12-V battery and a high-voltage (HV) dc bus in a fuel cell car, is derived. The nominal power is 2 kW, the HV dc bus varies between 240 and 450 V, and the battery voltage range is between 11 and 16 V. Consequently, battery currents of up to 200 A occur at nominal power. In automotive applications, high converter efficiency and high power densities are required. Thus, it is necessary to accurately predict the dissipated power for each power component in order to identify and to properly design the heavily loaded parts of the converter. In combination with measured efficiency values, it is shown that conventional converter analysis predicts substantially inaccurate efficiencies for the given converter. This paper describes the main reasons why the conventional method fails and documents the different steps required to predict the power losses more accurately. With the presented converter prototype, an efficiency of more than 92% is achieved at an output power of 2 kW in a wide input/output voltage range.
TL;DR: The allowable range of motor-parameter changes is determined, which guarantees the stable operation of the sensorless field-oriented IM drive with this speed and flux estimator, and the stability of the whole drive system is guaranteed.
Abstract: This paper deals with an analysis of the vector-controlled induction-motor (IM) drive with a novel model reference adaptive system (MRAS)-type rotor speed estimator. A stability-analysis method of this novel MRAS estimator is shown. The influence of equivalent-circuit parameter changes of the IM on the pole placement of the estimator transfer function and the stability of the whole drive system are analyzed and tested. The influence of the adaptation-algorithm coefficients of the MRAS-estimator scheme is also tested. The allowable range of motor-parameter changes is determined, which guarantees the stable operation of the sensorless field-oriented IM drive with this speed and flux estimator. Dynamical performances of the vector-control system with the current-type MRAS estimator are tested in a laboratory setup.
TL;DR: This paper presents supercapacitor (SCAP) and battery modeling with an original energy management strategy in a hybrid storage technology and results obtained from the polynomial control strategy are presented, analyzed, and compared with that of classical proportional-integral control.
Abstract: This paper presents supercapacitor (SCAP) and battery modeling with an original energy management strategy in a hybrid storage technology. The studied dc power supply is composed of SCAPs and batteries. SCAPs are dimensioned for peak power requirement, and batteries provide the power in steady state. A bidirectional dc/dc converter is used between SCAPs and the dc bus. Batteries are directly connected to the dc bus. The originality of this study is focused on SCAP behavior modeling and energy management strategy. The proposed strategy is based on a polynomial (RST) controller. For reasons of cost and existing components (not optimized) such as batteries and semiconductors, the experimental test benches are designed in reduced scale. The characterized packs of SCAPs include two modules of ten cells in series for each one and present a maximum voltage of 27 V. The proposed strategy is implemented on a PIC18F4431 microcontroller for two dc/dc converter topology controls. Experimental and simulation results obtained from the polynomial control strategy are presented, analyzed, and compared with that of classical proportional-integral control.
TL;DR: Possessing the very optimal ZVS +ZCS soft-switching feature, this proposed converter will have a minimized switching loss if all of the main switches are implemented with metal-oxide-semiconductor field-effect transistors, and thereby, the proposed converter is fully soft switched and totally snubberless.
Abstract: A bidirectional DC-DC converter (BDC) with a new CLLC-type resonant tank, which features zero-voltage switching (ZVS) for the input inverting choppers and zero-current switching (ZCS) for the output rectifier switches, regardless of the direction of the power flow, is proposed in this paper. Possessing the very optimal ZVS +ZCS soft-switching feature, this proposed converter will have a minimized switching loss if all of the main switches are implemented with metal-oxide-semiconductor field-effect transistors, and thereby, the proposed converter is fully soft switched and totally snubberless. The detail operation principles, as well as the design considerations, are presented. The methodologies to develop a unidirectional ZVS+ZCS dc-dc converter for the corresponding pulsewidth modulation and frequency modulation converters are proposed. The approach on how to construct a fully soft-switched BDC has also been proposed and analyzed. Finally, a topology extension is made, and another fully soft-switched BDC is derived. A prototype, which interfaces the 400-48-V dc buses for the uninterrupted power supply system with a power rating of 500 VA, was developed to verify the validity and applicability of this proposed converter. The highest applicable conversion efficiencies for the bidirectional operational modes are exceeding 96%.
TL;DR: It can be concluded that multilevel inverters can significantly increase their availability and are able to operate even with some faulty components.
Abstract: This paper is related to faults that can appear in multilevel (ML) inverters, which have a high number of components. This is a subject of increasing importance in high-power inverters. First, methods to identify a fault are classified and briefly described for each topology. In addition, a number of strategies and hardware modifications that allow for operation in faulty conditions are also presented. As a result of the analyzed works, it can be concluded that ML inverters can significantly increase their availability and are able to operate even with some faulty components.
TL;DR: A computational control delay compensation method, which delaylessly and accurately generates the SAPF reference currents, is proposed, and various simulation and experimental results demonstrate the high performance of the nonlinear controller.
Abstract: This paper presents a nonlinear control technique for a three-phase shunt active power filter (SAPF). The method provides compensation for reactive, unbalanced, and harmonic load current components. A proportional-integral (PI) control law is derived through linearization of the inherently nonlinear SAPF system model, so that the tasks of current control dynamics and dc capacitor voltage dynamics become decoupled. This decoupling allows us to control the SAPF output currents and the dc bus voltage independently of each other, thereby providing either one of these decoupled subsystems a dynamic response that significantly slower than that of the other. To overcome the drawbacks of the conventional method, a computational control delay compensation method, which delaylessly and accurately generates the SAPF reference currents, is proposed. The first step is to extract the SAPF reference currents from the sensed nonlinear load currents by applying the synchronous reference frame method, where a three-phase diode bridge rectifier with R-L load is taken as the nonlinear load, and then, the reference currents are modified, so that the delay will be compensated. The converter, which is controlled by the described control strategy, guarantees balanced overall supply currents, unity displacement power factor, and reduced harmonic load currents in the common coupling point. Various simulation and experimental results demonstrate the high performance of the nonlinear controller.
TL;DR: This new topology has the potential to increase the efficiency and reduce the cost of high-power pickups by minimizing the reactive currents in the pickup coil and the reflected VAR loading on the power supply.
Abstract: This paper describes the design of a new unity-power-factor inductive-power-transfer (IPT) pickup using an LCL tuned network for application in high-power systems. This new topology has the potential to increase the efficiency and reduce the cost of high-power pickups by minimizing the reactive currents in the pickup coil and the reflected VAR loading on the power supply. In a practical system, the rectifier and associated processing circuitry distorts the current waveforms, adding an effective inductive loading to the pickup circuit. A series compensation capacitor is added to correct this loading. A design strategy is developed for the new topology, and two example circuits are constructed and compared experimentally with a traditional parallel-tuned (LC) pickup operating on a monorail-based IPT system.
TL;DR: A nonlinear sliding-mode speed-control scheme for interior permanent-magnet synchronous motor drives incorporating the maximum-torque-per-ampere trajectory is proposed, capable of exhibiting high dynamic and steady-state performances over a wide speed range.
Abstract: This paper proposes a nonlinear sliding-mode speed-control scheme for interior permanent-magnet synchronous motor (IPMSM) drives incorporating the maximum-torque-per-ampere trajectory. The drive uses an adaptive sliding-mode observer (SMO) for rotor-speed estimation. The global asymptotic stabilities of both the controller and observer are guaranteed by Lyapunov stability analysis. The very low speed and standstill performance of the drive is further enhanced by combining high-frequency signal injection with the SMO. Hence, the sensorless drive is capable of exhibiting high dynamic and steady-state performances over a wide speed range. Experimental results confirm the effectiveness of the proposed method.
TL;DR: A WT condition monitoring technique that uses the generator output power and rotational speed to derive a fault detection signal and uses a continuous-wavelet-transform-based adaptive filter to track the energy in the prescribed time-varying fault-related frequency bands in the power signal.
Abstract: Cost-effective wind turbine (WT) condition monitoring assumes more importance as turbine sizes increase and they are placed in more remote locations, for example, offshore. Conventional condition monitoring techniques, such as vibration, lubrication oil, and generator current signal analysis, require the deployment of a variety of sensors and computationally intensive analysis techniques. This paper describes a WT condition monitoring technique that uses the generator output power and rotational speed to derive a fault detection signal. The detection algorithm uses a continuous-wavelet-transform-based adaptive filter to track the energy in the prescribed time-varying fault-related frequency bands in the power signal. The central frequency of the filter is controlled by the generator speed, and the filter bandwidth is adapted to the speed fluctuation. Using this technique, fault features can be extracted, with low calculation times, from direct- or indirect-drive fixed- or variable-speed WTs. The proposed technique has been validated experimentally on a WT drive train test rig. A synchronous or induction generator was successively installed on the test rig, and both mechanical and electrical fault like perturbations were successfully detected when applied to the test rig.
TL;DR: A novel high step-up dc-dc converter for fuel cell energy conversion that utilizes a multiwinding coupled inductor and a voltage doubler to achieve highstep-up voltage gain and high conversion efficiency.
Abstract: A novel high step-up dc-dc converter for fuel cell energy conversion is presented in this paper. The proposed converter utilizes a multiwinding coupled inductor and a voltage doubler to achieve high step-up voltage gain. The voltage on the active switch is clamped, and the energy stored in the leakage inductor is recycled. Therefore, the voltage stress on the active switch is reduced, and the conversion efficiency is improved. Finally, a 750-W laboratory prototype converter supplied by a proton exchange membrane fuel cell power source and an output voltage of 400 V is implemented. The experimental results verify the performances, including high voltage gain, high conversion efficiency, and the effective suppression of the voltage stress on power devices. The proposed high step-up converter can feasibly be used for low-input-voltage fuel cell power conversion applications.