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This paper presents a novel system that allows elevating large structures by using a set of lifting towers that, adequately controlled with a synchronized operation, succeed in pulling the spatial mesh up to the height where it should stay. By doing so, the mounting of the spatial mesh can be carried out on the ground in an easier and, most important of all, safer way; it also gives rise to a shorter final time and, thereby, a cost reduction. This paper deals with the elevation system designed to pull the mesh up and specifically focuses on the electronic system that allows controlling their movement. Comments about the overall control that coordinates the operation of all of the mechanical structures involved are also provided. [ABSTRACT FROM AUTHOR]

During routine commissioning of a steam turbine load-sharing system, serious low-load frequency instabilities were discovered. These instabilities were causing undamped oscillations in power and frequency to escalate until protective relays tripped a generator offline. Root-cause investigation led to a robust solution and some rather startling revelations about the implications of electronic governor controls and small (micro) grids. There are basically two ways to form an electronic governor control loop with droop: 1) speed control with a MW droop; or 2) MW control with a speed droop. The analysis in this paper shows one method to be superior under low-load conditions. The results of this analysis have implications for the frequency stability of the power grid today. Microgrids, green energy, distributed generation, and isolated industrial plants can all be susceptible to this instability. The authors estimate that approximately 60% of today's generation is prone to destabilize the power system frequency under low-load conditions. [ABSTRACT FROM PUBLISHER]

Energy harvesting has become a popular source for low-power electronic systems such as wireless sensors and biomedical implants. Energy can be extracted from a number of ambient conditions such as vibration, solar, and thermal gradient. Just like renewable sources, the associated switching power converters can be controlled to harvest maximum power from these miniature systems. However, conventional schemes, such as a conventional maximum power point tracking (MPPT) controller for solar cells, are complex and cannot be utilized in low-power energy systems due to their cost and power requirements. In this paper, a novel optimum energy harvesting scheme is proposed, which controls the duty cycle of the converter to maximize the output power of the system. The control system employs only simple mixed-signal components and can be applied to low-power systems. The proposed scheme does not depend on the characteristics of a specific source and is applicable for different energy systems. In this paper, it is utilized to achieve optimized energy harvesting for two completely different fixed excitation systems, namely, a low-voltage vibration-based electromagnetic microgenerator and a miniature solar cell array. Both simulation and experimental results are provided to validate the proposed scheme. [ABSTRACT FROM PUBLISHER]

Current control in inverter-driven machine systems is the inner most component of the hierarchy of control loops. If the control of current in the machine is not fast and accurate then it is difficult, if not impossible, to build a high-performance drive system. Unfortunately, the implementation of current control in power electronic systems is not ideal. Practical effects can have a significant influence on its performance. This paper examines one of these effects, dead time, and considers the influence it has on the performance of predictive current controllers (PCCs). The paper presents analysis that shows that a PCC implicitly compensates for voltage loss due to dead time. Also, a modified PCC is introduced that reduces the zero-current-clamp problem caused by dead time. Simulation and experimental results are presented to verify the analysis and confirm the performance of the new algorithm. [ABSTRACT FROM AUTHOR]

The application of residual-current principle, as carried out by zero-sequence current protective devices, is one of the most efficient ways to reduce the hazard of electric shock in case of a failure of the equipment's basic insulation to ground. Highly sensitive and regularly tested residual-current-operated circuit breakers without integral overcurrent protection (RCCBs) devices are rightfully recognized worldwide by standards and codes as an effective means to protect persons against direct and indirect contact with energized parts by disconnecting the supply in a timely fashion. These devices are also referred to as ground-fault circuit interrupters. The protective action of the RCCBs, however, can be nullified not only due to internal malfunctions of the device but also due to particular ground-fault conditions. In these dangerous situations for persons, for example, accidental direct contact with two parts at different potentials, the residual current flowing through the RCCB is below its residual operating value, and therefore, it cannot trip. This hazardous circumstance exposes persons to dangerous touch voltages despite the presence of an efficient protective device, which cannot be blamed for not intervening. This paper seeks to clarify these particular fault conditions occurring even in the presence of healthy RCCBs. [ABSTRACT FROM AUTHOR]

This paper presents an embedded digital system for incremental encoders allowing for high dynamic performance and accuracy speed measurement in all the operating conditions for the application in digital servo drives. The idea aims at embedding processing capabilities inside traditional position transducers in order to develop a smart measuring system. The base processing algorithm employs a novel mixed time and frequency measurement technique of the encoder signals. The iterative formulation of the algorithm and the limited hardware requirements allows its implementation by means of a standard microcontroller (e.g., TMS32OF24x) or by dedicated hardware. Communication between the smart sensor and the servo drive is preliminarily realized via high-speed serial peripheral interface. [ABSTRACT FROM AUTHOR]

Speed and position sensing in servo drives is an issue that is still not completely understood. Expressions like "accuracy" and "resolution" still get mixed up when engineers talk about encoders. These words, however, do describe different characteristics and should not be confused. The introduction of digital control has made this issue much more important for servo drive applications than before. This paper presents some general explanations of speed and motion sensing as well as different encoder technologies available today and their characteristics, particularly with respect to digitally controlled servo drives. [ABSTRACT FROM AUTHOR]

In recent years, passive integrated power electronic modules (IPEMs), which have been implemented as resonant tanks in resonant dc-dc converters, have gained interest because of their merits for possibly reducing the total volume and improving manufacturability of the resonant converter system. However, the integration process for the passive IPEM increases the complexity of the thermal and mechanical behavior of the structure due to interactive heating of the module layers and mechanical inter-layer stresses. It is therefore essential to investigate the thermo-mechanical behavior of a passive IPEM to ensure reliable operation. In this paper, the methodology for thermo-mechanical analysis for a series resonant LC passive IPEM is developed. Especially, a three-dimensional thermo-mechanical model based on finite-element modeling is presented. The thermal analysis results were verified by an experimental prototype LC passive IPEM and temperature distribution measurement using an infrared camera and thermocouples. Results of the thermal analysis and the associated thermo-mechanical stress analysis are also discussed, illustrating the viability of the methodology developed for thermally induced mechanical stresses. [ABSTRACT FROM AUTHOR]

Considering fault current limiters for serial protection, many structures exist, from regulation to other complex systems such as circuit breakers, mechanical switches, or more conventional fuses. Up to now, only a few semiconductor current limiter structures have been described in the literature. Although current-regulative diode components already exist, their voltage and current capabilities (V[subBR] = 100 V, I[submax] = 10 mA), do not allow their use in power systems. This paper presents both simulation study and experimental results of a bidirectional current limiter structure based on a vertical SiC VJFET. The device was designed for serial protection in order to limit I²t value. Finite-element simulations were performed with ISE-TCAD software to design the device and evaluate its static electrical characteristics. Then, dynamic simulations were performed to underline current reduction ability and power losses adjustment by gate resistance value optimization. Finally, electrical characterization for a unidirectional and a bidirectional device were done up to 400 V. The measured specific on resistance R[sub ON] is in the range of 176 mΩ · cm². Limiting capabilities have also been measured for a bidirectional device made of two unidirectional devices connected head to tail. The highest breakdown voltage value in "current limiting state" was measured to be ∼810 V, corresponding to a high power density of 140 kW/cm². [ABSTRACT FROM AUTHOR]

Multiple grounded neutral systems require that, on most land-based ac current service installations, the bonding conductor used to connect the non-current-carrying metal parts of equipment, the system grounded conductor (neutral), and the grounding electrodes be bonded together at the service entrance box. Users thus share their ground with the serving utility's neutral ground. This interconnection, although functional, poses some distinctive problems to utility companies as well as to users, which this paper seeks to clarify. [ABSTRACT FROM AUTHOR]

In this paper, two reversible single-phase-to-threephase ac drive systems are proposed. They are composed of an induction motor fed by two parallel single-phase-to-three-phase dc-link converters without isolation transformers. Suitable modeling and control strategy of the systems based on odq approach, including the unbalanced case, are developed. The proposed topologies permit reducing the harmonic distortion and presents fault tolerance characteristics. Even if the number of switches is increased, the total energy loss of the proposed systems can be lower than that of a conventional one. It is shown that the reduction of the circulating current is an important objective for the system design. A single-phase-to-three-phase dc-link converter generalization has been proposed as well. Simulated and experimental results are presented. [ABSTRACT FROM AUTHOR]

The direct measurement of losses in power electronic systems is possible through the use of a calorimeter. An improved and fully automated version of a double-jacketed closed-type calorimeter is described in this paper. The accuracy of the calorimeter has been confirmed by calibration tests and is better than 0.1 W in 25 W. The losses in mobile (cell phone) chargers and the ballasts of compact fluorescent lamps have been measured in this calorimeter and are compared to those obtained from conventional measurement methods. [ABSTRACT FROM AUTHOR]

10-kV silicon carbide (SiC) MOSFETs are currently being developed by a number of organizations in the U.S. with prospective applications in high-voltage and high-frequency power-electronic systems. The aim of this paper is to demonstrate the high-frequency and high-temperature capability of 10-kV SiC MOSFETs in the application of a dc/dc boost converter. In this study, 10-kV SiC MOSFET and junction barrier Schottky (JBS) diode were characterized and modeled in SPICE. Following this, a dc/dc boost converter based on a 10-kV 10-A MOSFET and a 10-kV 5-A JBS diode was designed and tested under continuous operation for frequencies up to 25 kHz. The boost converter had an output voltage of 4 kV, an output power of 4 kW, and operated with a junction temperature of 174 °C for the SiC MOSFET. The fast-switching speed, low losses, and high-temperature operation capability of 10-kV SiC MOSFETs demonstrated in the dc/dc boost converter make them attractive for high-frequency and high-voltage power-conversion applications. [ABSTRACT FROM AUTHOR]

In this paper, a new online capacitance estimation method for dc-link capacitors in a three-phase ac/dc/ac pulsewidth-modulation converter is proposed. A controlled ac voltage with a lower frequency than the line frequency is injected into the dc-link voltage, which then causes ac power ripples at the dc output side. By extracting the ac power component on the dc output side using digital filters, the capacitance can then be calculated using a support vector regression method. A function that defines the relation between a given capacitor power and its corresponding capacitance is determined using a set of training data. This function is then used to predict the output for the given input which is not included in the training set. The proposed method can be simply implemented with only software and no additional hardware. Experimental results confirm that the estimation error is less than 0.15%. [ABSTRACT FROM AUTHOR]

This paper provides the framework to establish a coordinated grounding and bonding design plan. It also sets guidelines on how to apply the IEEE "Green" and "Emerald" Books, as well as other standards, to implement an effective grounding and bonding plan. Various systems encountered in a plant environment, and the grounding needs of the systems, are described. High-frequency grounding techniques, as applicable to lightning protection and electronic systems, are recommended to minimize erratic system operation. All grounding systems need to be conductivity bonded together to avoid system problems. All grounding and conductive paths need to be engineered and considered as part of the ground system design. [ABSTRACT FROM AUTHOR]

This article presents a discrete convolution-based method for reliability evaluation of a grid-connected photovoltaic (PV) system, where special consideration is given to the variable availability of PV array components. Along with the negative impacts of variable solar irradiance and ambient temperature on the PV power generation, they affect the reliability of PV system power electronic components. A variable availability model based on the power loss in the semiconductors of PV system components is needed to account for this effect in the reliability analysis. The article proposes a 3-D capacity outage model of a PV farm that accounts for the variable availability and the redundancies associated with the topologically complex multistring PV arrays. The outage model is used to construct a PV capacity outage probability and frequency table (COPAFT), which along with conventional generation COPAFT, is convolved with the distribution of load to determine system reliability. An integration limit assessment tool is also developed within the proposed framework, ensuring that the PV power integration does not violate the system frequency stability. Simulations on the modified IEEE RTS-79 system demonstrate the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

With the increasing demand for high-performance power electronic systems, the semiconductor device utilization has gained significant importance. This article proposes the Si/SiC devices based active neutral-point-clamped converter comprising SiC-based H-bridge structure. A novel pulsewidth modulation (PWM) scheme is also proposed that results in an effective utilization of the switching devices. In the proposed converter, the Si devices are soft-switched for all power-factor loading conditions. Therefore, high efficiency can be obtained even at high switching frequency operation with wide range of power factor values. Further, the conduction losses of the SiC mosfets are minimized by strategically selecting the switching states in such a way that the SiC mosfets conduct in parallel conduction paths during the null state operation. This leads to further enhanced efficiency. This article presents the detailed operating principle of the proposed topology operated with the presented PWM scheme. Moreover, a device loss analysis is presented to evaluate the conduction and switching losses of the proposed topology. The presented experimental results validate the performance parameters of the proposed topology with the proposed PWM scheme. Finally, the proposed PWM scheme is compared with the existing PWM schemes using efficiency values of the proposed and some of the prominent existing converter configurations. [ABSTRACT FROM AUTHOR]

The control of very high switching frequency power electronic converter systems featuring latest generation wide bandgap devices requires current measurements with a very high bandwidth (BW) to achieve high closed-loop control dynamics. One example is an ultrahigh BW $\mathbf {4.8}$ MHz parallel-interleaved multilevel GaN inverter ac power source with a target large-signal output BW of $\mathbf {100}$ kHz. This work investigates the combination of commercially available low-frequency (LF) Hall-effect current sensors (BW $\mathbf {\approx 1}$ MHz) with suitable high-frequency (HF) sensors to extend the BW above $\mathbf {10}$ MHz, i.e., enough to measure the HF inductor current. Based on a conventional PCB-integrated Rogowski coil, for the HF sensor, three improved pickup coil (PUC) geometries based on proposals in the literature are investigated. The LF and HF sensor signals are combined with a precision fully differential combiner circuit. Design guidelines for the HF sensors as well as the combiner circuit are presented and thereby the influence of mismatches and tolerances is examined. The performance of the proposed HF sensors is experimentally verified and compared with previous solutions based on galvanically isolated inductor voltage sensing and a current transformer. The PUCs reach a BW $\mathbf {>50}$ MHz, which is an improvement by more than a factor of $\mathbf {50}$ compared to the fastest available Hall sensor. Furthermore, it is proven that all investigated sensors are capable to accurately measure the triangular inductor current ripple in a hardware prototype of the aforementioned ac power source. In a final step, the influence of common-mode (CM) disturbances originating from fast $\mathbf {{d}v/{d}t}$ switching transients on the sensor performance is analyzed. The presented current sensors achieve a CM rejection ratio of almost $\mathbf {100}$ dB. [ABSTRACT FROM AUTHOR]

An interleaved reduced-component-count dc/dc converter is proposed for power management in fuel cell powered vehicles with a multivoltage electric net. The converter is based on a simplified topology and can handle more power with less ripple current, therefore reducing the capacitor requirements, making it more suited for fuel cell powered vehicles in the near future. A prototype rated at 4.3 kW was built and tested to verify the proposed topology. [ABSTRACT FROM AUTHOR]

An experimental investigation of indirect electrostatic discharge (ESD) events for an inline three-body geometry was undertaken. Using conducting cylinders of different sizes to model the test system's conductors, capacitance coefficients were measured; body potential differences and electric fields in air gaps were calculated for different geometries of the three floating conductors in close proximity. The test geometry was chosen to model the approach of the charged human body to an electronic system that has a neighboring floating conductor. The possibility of primary and secondary discharges was studied for various body sizes and test geometries. The results of this work provide a better understanding of the fundamental principles involved in the ESD event involving three bodies separated by small gaps. The methodology may have application in analyzing ESD events in small-gap structures including microelectromechanical systems (MEMSs). [ABSTRACT FROM AUTHOR]

The electrostatic discharge (ESD) characteristics of a three-body problem comprised of a charged human body approaching an electronic system with an interposed guard electrode are investigated. Capacitance coefficients were measured for various three conductor arrangements; for an assumed charge on the human body, body potentials were calculated and the relative effectiveness of different guard electrode geometries to control the ESD event compared. The results provide a better understanding of the fundamental principles involved in the ESD event involving three bodies and basic application in the design of interfaces between the charged human body and electronic systems. [ABSTRACT FROM AUTHOR]

Analyzes a series of active filter integrated with a double-series diode rectifier. Details of the survey of dynamic models for power electronic systems; Information on the system configuration; Experimental results.

The use of variable speed drives made essential the presence of power electronic in electrical systems. The ac to dc and dc to ac conversions, thanks to rectifiers and inverters cause difficulties in the ground fault detection. In this article, a new method to detect ground faults in variable speed drives is presented. It is based on the analysis of the terminal voltage signal of a grounding resistor connected between the neutral at the secondary of the main power transformer and ground. Attending to the waveform, the ground fault can be detected on the ac grid side, dc positive or negative terminals, or ac inverter side. To verify the method, numerous simulations and experimental tests in a 140-kW power converter were carried out achieving satisfactory results. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) mosfets are getting popular in high-frequency power electronic (PE) applications. More and more concerns for system efficiency and reliability are growing due to the increasing switching losses and thermal stress. In this article, an electro-thermal simulation method for SiC mosfets in modern PE systems is proposed. In the device simulation, a behavioral transient model of SiC mosfets is developed and used for generating a multidimensional power loss table in a wide range of operating conditions. The effects of parasitic elements, temperature-dependent parameters, and reverse recovery effect of the diode are taken into account. Furthermore, the power loss look-up table is integrated into the PE system simulation with an additional Cauer-based dynamic thermal model considering heatsink impact. In this way, the instantaneous power losses and junction temperature can be obtained, respectively, with fast simulation speed, reasonable accuracy, and improved simulation convergence. The proposed approach is implemented in PSCAD/EMTDC and further validated by the experimental results of a double pulse test setup and a power factor correction system. [ABSTRACT FROM AUTHOR]

Strategies to implement emulation of large power electronic converters with different topologies using a generic multiport decomposition technique with different levels by exploiting the parallel nature of field programmable gate array (FPGA) are explained in this article. Switches are modeled as on/off resistors and a Python-based software tool is developed to precompute the system matrices corresponding to each switch combination. Converters like three-phase five-level-flying-capacitor are modeled in C using the precomputed data, converted to VHDL and implemented on ZCU104 and ZedBoard using Vivado and verified against the corresponding MATLAB-Simulink model. Also, the real-time performance is analyzed by connecting it for the closed-loop speed control of induction motors of various specifications by changing the load torque and reference speed and found out that the latency is less than 6 μs, which is sufficient for the wide range of variable frequency drive applications. [ABSTRACT FROM AUTHOR]

Nowadays, different industries such as nuclear, automotive, process, chemical, and oil and gas industry must meet specific requirements in order to keep and reduce safety risks to as low as reasonably practicable level. As a result, the number of electrical/electronic/programmable electronic safety-related systems (E/E/PES) to control, prevent, and mitigate hazardous events has increased. Moreover, new guidelines and procedures have been developed to guarantee the availability and function of safety systems over their service life. Based on Markov processes, this article discusses a reliability model to assess the integrity and verify the design of E/E/PES safety-related systems. The average probability of failure on demand and safety integrity level are used to determine the reliability performance of an E/E/PES in a low-demand mode of operation in accordance with the functional safety principles of the IEC 61508 and IEC 61511 standards. [ABSTRACT FROM AUTHOR]

The estimation of phase-angle, frequency, and amplitude are vital for the control of grid-connected power electronic systems in both single-phase and three-phase systems. The single-phase enhanced phase-locked loop (1P-EPLL) and two-phase enhanced phase-locked loop (2P-EPLL) techniques can be used to estimate single-phase and three-phase grid voltage quantities, respectively. However, under the presence of harmonics, unbalance, and dc offsets, the estimated quantities by these enhanced phase-locked loops (EPLLs) may contain periodic ripples. These periodic ripples are eliminated by using multiple delayed signal cancellation (MDSC) filters in the phase-angle estimation loop and amplitude estimation loop of these EPLLs. To improve the dynamic responses of MDSC-based EPLLs, proportional-integral (PI) controller is replaced with a proportional-integral-derivative (PID) controller. The design guidelines for choosing the control parameters are provided. The MDSC filters in the EPLLs are realized both in direct-form and recursive-form structures. The proposed EPLLs are verified experimentally by using real-time system and compared with recent advanced EPLLs. [ABSTRACT FROM AUTHOR]

In an organic Rankine Cycle system, the permanent magnet (PM) generator is directly coupled to high-speed turbine shaft, to increase system efficiency avoiding the gearbox introduction. Current time harmonics induce high-frequency currents in rotor parts, which cause temperature increase. PMs are strongly affected by the operating temperature, since both remanence and coercive force decrease. This article shows that rotor losses of a high-speed PM generator strongly depend on both winding arrangement and power electronic conversion system connected to the generator itself. Several analyses are carried out to compare different solutions. [ABSTRACT FROM AUTHOR]

The effects of internal feedback through device parasitic capacitances and inductances associated with the gate-drive signal on the turn-off loss of a MOSFET operating as a zero-voltage switch in a class-D resonant inverter were studied. Expressions relating the parameters of Miller feedback and gate-drive circuit to Miller voltage were formulated. Impeding turn-off and return on of the conduction channel were found to be responsible for higher turn-off loss. Switching trajectories, energy transferred into the MOSFET in each switching cycle, as well as turn-off loss for different gate-drive signals, were calculated using data obtained from computer simulations. The results were compared with those calculated from experimental data. The voltage-dependent parasitic capacitances of the MOSFET were estimated from the experimental data and used for the calculation of channel current. [ABSTRACT FROM AUTHOR]

An experimental investigation of indirect electrostatic discharge events for an inline three-body geometry was undertaken. Using conducting cylinders of different sizes to model the test system's conductors, capacitance coefficients were measured, and body potential differences and electric fields were calculated for different geometries of the three floating conductors in close vicinity. The test geometry was chosen to model the approach of the charged human body to an electronic system, which has a neighboring floating conductor; this situation may arise in a manufacturing environment where faulty grounding exists. The parameters studied include body sizes, test geometry, and the relative magnitude and polarity of the charges on the three bodies. An analysis of both first and secondary discharge events is presented and interpreted using a series of charge sensitivity factors. Conditions to support secondary discharges are investigated as a two-body problem. [ABSTRACT FROM AUTHOR]

Presents a study which assessed potential differences for a three-body geometry. Significance of the Maxwell equation in defining the system of an electrostatic discharge (ESD); Discussion on the concept of a modular grid to control ESD in electronic systems; Investigation on the characteristics of a three-body system.