Power Electronic Circuits Research Articles

An Accurate and Fast Method for Conducted EMI Modeling and Simulation of MMC-Based HVdc Converter Station

The analysis of electromagnetic interference (EMI) noise of power electronic circuits involves both the transient characteristics of power semiconductor devices and the wideband stray parameters of passive equipment. Modular multilevel converters (MMCs) used in high-voltage direct current (HVdc) transmission systems contain thousands of submodules (SMs), which makes it considerably challenging to perform device-level simulation on the traditional commercial software. This article presents an accurate and fast method for wideband modeling and simulation of MMC-HVdc system for the assessment of conducted EMI during the design stage. Physical characteristics of the semiconductor devices, parasitic parameters of the insulated-gate bipolar transistor (IGBT) packages, and stray capacitances of the SMs are all taken into consideration, and massively parallel transient simulation of the wideband MMC model is carried out on the graphics processor (GPU). The accuracy and efficiency of the GPU-based parallel algorithm are validated by the comparison with the experimental measurement of an 11-level full-bridge MMC prototype. Furthermore, the stray capacitance network of the valve tower in HVdc project is extracted, and a matrix partition method based on the shielding plate configuration is utilized to conduct the computation in a fully parallelized manner. The developed GPU program is used to run the large-scale case of a 201-level two-terminal MMC-HVdc system, and the primarily affected frequency range by various factors is analyzed. Execution time test is conducted for different level topology, and it is demonstrated that the GPU can achieve a remarkable speedup over multicore CPUs, especially when the system scale is more substantial.

Output power smoothing of wind power plants using self-tuned controlled SMES units

This paper exhibits a new application of the continuous mixed p-norm (CMPN) algorithm to self-tune all controlled superconducting magnetic energy storage (SMES) units to smooth wind power plants output power. The proposed algorithm is applied to self-tune all PI controllers of these storage units. In the present article, two wind farms are connected with the power grid. Each wind farm is equipped with a self-tuned (ST) controlled SMES unit. The control strategy of this unit is based on a voltage source converter (VSC) and a DC chopper. The VSC is implemented to control the reactive power and the DC chopper is utilized to control the real power exchange with the power grid. These aforementioned power electronic circuits are fully controlled by the proposed CMPN-ST-PI controllers. To achieve more realistic studies, measured values of wind speed that captured from Hokkaido wind power plants are implemented in system investigation. In addition, the turbine model depends on a two-mass structure, which highly affects system dynamics. Moreover, a practical SMES device of a rated capacity of 10 MVA, which is established in Kameyama, is joined the PCC of wind power plants. The proposed self-tuned controller is validated by using the simulation results, which are extensively performed on PSCAD program. The effectiveness of proposed adaptive controlled SMES devices is compared with that obtained by using optimal genetic algorithm-based PI controlled SMES devices under wind speed uncertainty conditions. With these CMPN-ST-PI controllers, the output power of wind power plants can be further smoothed and its fluctuations can be depressed.

Modeling and Simulation of the Flyback Converter using SPICE Model

This paper presents to find a sufficient model of integrated passive structures for high frequency analysis and prediction in power electronic circuits. At high frequencies there are many parasitic oscillations that begin to circulate in the power circuits. Some sources of these oscillations include inter-component connections and their environment begin having electromagnetic significance, unmodeled characteristics in the semiconductor devices, Parasitic impedance characteristics of discrete passive components, Interference from an imperfect source and a ground plane and Interference from radiation. A simulation model involving most of these factors can prove valuable in distinguishing between the causes of parasitic oscillations. A designer can modify the parameters of a particular parasitic element, and observe its effect on the oscillations, hence seeing which factors are the most significant.

Effect of Perforation on the Thermal and Electrical Breakdown of Self‐Rolled‐Up Nanomembrane Structures

AbstractStrain‐induced self‐rolled‐up membranes (S‐RuM) are structures formed spontaneously by releasing a strained layer or layer stacks from its mechanical support, with unique applications in passive photonics, electronics, and bioengineering. Depending on the thermal properties of the strained layers, these structures can experience various thermally induced deformations. These deformations can be avoided and augmented with the addition of strategically placed perforations in the membrane. This study reports on the use of perforations to modify the thermal effects on strained silicon nitride S‐RuM structures. A programmable fuse with well‐defined thermal threshold, ultrasmall footprint, and 2–3 V voltage rating is demonstrated, which can potentially serve as an on‐chip sensing device for power electronic circuits.

Analysis and Modeling of SiC JFET Bi-Directional Switches Parasitic Oscillation

Silicon carbide (SiC) junction field-effect transistor (JFET) based bi-directional switches (BDSs) have great potential in the construction of several power electronic circuits, including matrix converters, multi-level converters, solid state breakers, and so on. Parasitic oscillation in SiC JFET-based BDSs has direct impact on the stability and reliability of these circuits. Proper handling of parasitic oscillation becomes highly critical. This paper focuses on the parasitic oscillation suppression in SiC JFET-based BDSs. A parallel snubber capacitor or a series ferrite ring was often used to damp parasitic oscillation in switching circuits in the literature. However, conventionally, the snubber capacitance was obtained by time-consuming and labour-intensive trial-and-error methods. The main contribution of this study is to derive the simplified equivalent transient circuit of the SiC JFET-based BDS considering all parasitic elements and quantitatively define the reasonable range of the snubber capacitance. And the combined effect of the selected snubber capacitance and the selected ferrite ring is investigated. In the end, simulation and experimental results validate the effectiveness of the proposed method.

(Invited) Performance Evaluation of III-N Bipolar Switches Grown on GaN Substrates

The successful development of III-V nitride materials systems has led to active research of advanced electronic devices in the recent decades. III-nitride (III-N)-based devices have a bandgap engineering flexibility, large energy gap, direct band structure, and high carrier mobility when compared to Si- and SiC -based devices, providing new performance improvement opportunities for high-speed and energy-efficient electronics. Today, commercial GaN HFETs are available for microwave power amplifiers and power electronic circuits. On the other hand, the development of bipolar transistors and the related switch technologies are essential to fully exploit the potential of III-N materials systems. For instance, insulated-gate-bipolar transistors would require integrated bipolar transistor and unipolar transistor structures. The development of III-N bipolar switches in either two-terminal or three-terminal forms have therefore been actively sought. To this end, power switches that conduct the electric current in the vertical form are beneficial to achieve the ultimate Baliga’s Figure of Merit (BFOM) for switching. For GaN bipolar power switches development, low-defect-density native substrates, high-quality epitaxial growth technology, and proper device design and fabrication have become major focus areas of research. Early development of heterojunction bipolar transistors (HBTs) using GaN/InGaN heterojunctions at Georgia Tech showed promising device performance. These devices exhibited high-current gain of >100, high current drive density of >100 kA/cm2, and high d.c. power handling capability of > 3 MW/cm2. Small-signal microwave amplification with a cut-off frequency (f T) of 8GHz was reported. In this presentation, we will review the development status of III-N bipolar switches and use GaN rectifiers as a case study to discuss the device performance pertinent to the choices of GaN substrates prepared by different methods. The device structures were grown and fabricated at Georgia Tech and the device performance correlation with respect to the substrates were evaluated. High-power operation was demonstrated for homojunction GaN PIN rectifiers grown on a 2-inch bulk GaN substrate using a metalorganic chemical vapor deposition (MOCVD) reactor. The GaN substrate was prepared using a near-equilibrium ammonothermal (NEAT) method. The device fabrication employed an ion-implantation isolation, field plate, and electroplated copper electrodes. The fabricated devices have dimensions up to 1.1 mm in diameter and showed uniform V on of 3.6±0.1 V and an ideality factor of 2.08. A blocking voltage (BV) of >1.2 kV and the on-state resistance (R ON A) of 0.4 mΩ·cm2 were measured. For PIN rectifiers with a dimension of 1.1 mm in diameter, we reported a BV of 1,200 V and an on-state current drive of greater than 11 A (1 kA/cm2). These results demonstrated the feasibility of using bipolar carrier transport mechanisms and PN junctions in III-N devices for power amplifications and switching circuits.

Harmonic modeling of vibration energy harvesting systems using extended impedance method

Vibration energy harvesting (VEH) systems convert the mechanical vibration energy in AC form into storable electrical energy in DC form. The mechanical structure, electromechanical transducer, and power electronics are three necessary parts for realizing the electromechanical energy transduction and rectification. The difficulty was found in modeling the electromechanical joint dynamics, in particular, when complex mechanical dynamics or sophisticated electrical switching transient are involved. Harmonic analysis is proven to be an efficient tool for modeling such a multiple-field-coupled power conversion system. In this paper, we develop a multiple harmonics analysis for the piezoelectric energy harvesting systems based on the extended impedance method (EIM). This method was used in the analysis of nonlinear power electronic circuits, such as resonant inverters and dc-dc converters. The theoretical results at steady state are compared with the simulation results from the commercialized circuit simulation software. The new modeling technique provides an efficient tool for the customized design and holistic optimization of the vibration energy harvesting systems.

A Datasheet Driven Unified Si/SiC Compact IGBT Model for N-Channel and P-Channel Devices

This paper presents a unified physics-based insulated-gate bipolar transistor (IGBT) compact model for circuit simulation that predicts the performance of both Si and SiC, n- and p-channel devices. The model can predict the detailed switching waveforms of these technologies based on its charge-based formulation. Further, this compact IGBT model is presented alongside a unique datasheet-driven parameter extraction process. The parameter extraction process enables users to quickly extract model parameters from data typically published without the need of taking physical measurements. The model has been validated with both Si and SiC devices for static and dynamic characteristics. The SiC IGBTs used for validation are a 12.5-kV n-channel device and a 13-kV p-channel device, while the Si IGBT chosen was IXDH30N120 from IXYS Corp. (Milpitas, CA, USA). This is the only IGBT model that predicts the performance of both n- and p-channel, Si and SiC devices, providing more freedom for the development of complex power electronics circuit designs. The convergence of the model has been verified by implementing a complex circuit consisting of both a dc-dc converter and a dc-ac inverter. The results presented here show that the unified model can be used to describe the behavior of a wide range of Si and SiC IGBT circuits. This paper is accompanied by a Verilog-A source code and a power point file demonstrating the model parameter extraction sequence.

Application of an Efficient Rogowski Coil Sensor for Online Estimation of Turn-Off Energy Loss of Power Diodes

This paper deals with a new application for a special sort of Rogowski coil (RC) sensor in real-time estimation of diode turn-OFF energy loss. The turn-OFF energy loss of power diode is a key metric in designing power electronics circuits. The estimation accuracy of the diode turn-OFF energy loss significantly depends on the accurate extraction of diode reverse-recovery parameters during the turn-OFF process. By far, many methods have been proposed for offline estimation of diode reverse-recovery parameters. However, online estimation of these parameters can also provide worthwhile information for real-time monitoring of power diode and operating power electronics circuit. Specifically, the online estimated energy loss includes information which can be interpreted to obtain general ideas about the diode junction temperature, health status of snubber circuits, and so on. In this paper, a novel approach for online estimation of turn-OFF energy loss of power diodes using an efficient double-layer printed circuit board RC (DLPCBRC) sensor is proposed. The sensor is designed and utilized to acquire the key reverse-recovery parameters of the diode. Based on the extracted reverse-recovery parameters, a sufficiently good estimation of diode turn-OFF energy loss is obtained in real-time. The simulation and experimental results on a typical diode in a boost DC–DC converter are presented to demonstrate the effectiveness of the proposed approach.

A CFD simulation of the liquid-cooled pipe conductors for the high power and high frequency power electronic circuits

In recent years, depending on the developments in semiconductor technology; the performance of power electronic circuits has been increased significantly with higher power and higher switching frequency capability. However, the higher switching frequency increases both core and winding losses of the magnetic components (such as inductor and transformer) contained in the power electronics circuits. In high frequency inductors, during the rippled current flow, the winding conductors cause abnormal temperature rises due to the skin and proximity effects. This phenomenon cannot be precisely determined by mathematical methods in the design phase. In this study, the liquid cooled pipe conductors are recommended in the windings of high-frequency and high-power inductors employed in the power electronic circuits, which can be used in renewable energy systems and electric vehicles. These pipe conductors have been modeled with the Ansys-Mechanical Fluent software and the temperature values have been determined with the computational fluid dynamics (CFD) analysis. Thus, the cooling performance for the inductor winding versus the liquid circulation through the copper pipe conductor has been reported.

An FPGA-Based IGBT Behavioral Model With High Transient Resolution for Real-Time Simulation of Power Electronic Circuits

This paper presents a novel insulated gate bipolar transistor (IGBT) behavioral model on the field programmable gate array (FPGA), which is suitable for the real-time simulation of fast transients in power electronics circuits. In this model, the static and dynamic behaviors of the IGBT switch are described and modeled separately. The static IGBT model is represented by the saturation region of output characteristic and is a part of the circuit network model. The dynamic IGBT model is combined with the static one to describe the fast switching transient behaviors by using the IGBT equivalent circuit model. The presented dynamic model in this paper does not involve any iterative solving algorithm and can be designed with highly pipelined structures on FPGA. Therefore, the IGBT switching transient waveforms can be generated precisely with a 5 ns resolution. The proposed model is tested with two cases—a four-phase floating interleaved boost converter and a three-phase five-level modular multilevel converter. The effectiveness and accuracy of the model are validated by comparing the real-time simulation results with offline simulation software.

Adaptive Weighted VMD-WPEE Method of Power-Electronic-Circuit Multiple-Parameter-Fault Diagnosis

To improve the diagnostic accuracy rate of multiple parameter faults in widely used power electronic circuits, solving for the overlapping parameter fault characteristic signal is crucial. This paper proposes a novel approach for diagnosing the multiple parameter faults of power electronic circuits that can adaptively adjust the weights of each fault feature parameter according to the diagnostic accuracy rate to enhance their discriminability. According to the properties of multiple parameter faults in power electronic circuits, the measured signal that has been decomposed via the variational mode decomposition and wavelet packet energy entropy (VMD-WPEE) is used to extract the feature parameters. Furthermore, a classifier is selected and the threshold of the diagnostic accuracy rate is set. Then, the weight of each fault feature parameter is adjusted until the classifier yields the desired results. Finally, the proposed approach is applied to other classifiers and feature extraction methods. The high accuracy, high robustness, and advantages of the multiple-parameter-fault diagnosis method are demonstrated by the simulation and experimental results.

REVIEW ON MPPT TECHNIQUES USED IN PV SYSTEM

Production of fossil fuel energy is decreasing but the demand for electrical power is rapidly increasing day by day. Solar energy is used because it is clean energy, and also is abundant in nature and has a lot of scope for future development. Maximum power point tracking (MPPT) is an algorithm method used in power electronic circuits to extract maximum power from the solar Photo-voltaic (PV) Systems. This paper summarizes the development of a photo-voltaic solar system based techniques like Incremental conductance, Fractional open-circuit voltage, Perturb and observe, Fractional short-circuit current and Fuzzy logic that improves accuracy, stability, and efficiency of PV systems.

On the Practical Design of a Two-Terminal Active Capacitor

A two-terminal active capacitor concept has been proposed recently based on an active power electronic circuit with a voltage control method and self-power scheme. It retains the convenience of use as a passive capacitor with two power terminals only without any additional required connections and has the potential to either increase power density or reduce design cost depending on the applications. Based on the previously proof-of-concept study, this paper addresses the design constraints, impedance modeling, and start-up solutions of two-terminal active capacitors. A design method for functionality, efficiency, lifetime, and cost-constraint applications is applied to size the active components and passive elements. A voltage feedforward control scheme is implemented to improve its dynamic response. Two start-up solutions are proposed to overcome the issues brought by the self-power scheme. A case study of an active capacitor for the dc link of a single-phase full-bridge rectifier is presented to demonstrate the theoretical analyses.

Reliability of printed power resistor with thick-film copper terminals

This paper is focused on the thick-film power resistors with copper terminals. These terminals are created by the new Thick Printed Copper (TPC) technology. This technology is based on sequential screen printing and firing of copper paste in nitrogen atmosphere on an alumina substrate. Thick-film power resistor with copper terminals represents a potential replacement of standard wirewound power resistors and allows the direct integration of resistors on TPC substrates. Printed resistors on TPC substrates can be supplemented with discrete electronic components which creates the possibility to realize really complex power electronic circuits. The direct integration of printed components is not possible in case of using the standard Direct Bonded Copper (DBC) technology. The main benefits of printed resistors based on TPC technology are their low thickness and good thermal conductivity. The low thickness of resistors is important for miniaturization of final electronic devices. The resistor main electrical parameters as the temperature coefficient of resistance, temperature coefficient and nominal resistance value after dry heat aging and after thermal cycling, insulation resistance, dielectric strength etc., are described in this paper.

D-STATCOM for harmonic mitigation in low voltage distribution network with high penetration of nonlinear loads

With the increased use of power electronic for ac-to-dc converters, electrical distributions systems are experiencing an increased in non-linear loads. These non-linear loads, such as the classical rectifier, draw non-sinusoidal currents which tend to have a deleterious impact on the power quality of the modern AC distribution systems. The interaction of non-sinusoidal currents with the grid impedance leads to distorted system voltage which can adversely impact other devices connected to the grid. The integration of distributed energy resources (DERs) with the distribution power grid can further exacerbate the harmonic power issues. The traditional methods of compensation are no longer adequate and hence it is necessary to develop a means to provide local reactive and harmonic compensation at the source of the power quality problem within the low-voltage distribution network. This article investigates the use of a capacitor-less distribution static synchronous compensator (D-STATCOM) for power quality compensation in modern distribution systems. The proposed topology is based on a matrix converter (MC), controlled by finite control set model predictive control (FCS-MPC) which makes possible the use of inductive energy storage rather than electrolytic capacitors, which have been proven to be the most failure-prone components in a power electronic circuit. Simulation and experimental results are presented to validate the effectiveness of the approach.

Singular perturbation‐based model reduction of power electronic circuits

Here, the authors present a model order reduction (MOR) framework based on singular perturbation approximation to accelerate the simulation of high-fidelity power electronic converters. The problem of slow simulation speeds caused due to the wide span of the eigenvalues is mitigated by implementing the proposed framework. The dynamics of the original stiff system is approximated by neglecting the transient contribution of the non-dominant eigenvalues and retaining the steady-state contribution of all the eigenvalues of the system. The model reduction problem has been reformulated to fit the switched nature of these circuits. An error bound for the approximation method has been derived. The method is demonstrated on a DC–DC boost converter and a Class-E amplifier. Significant improvement in speed and reduction in the size of the solution arrays is achieved. It is seen that the reduced-order models are able to replicate the response of the original models and the approximation error is within acceptable limits.

A Single-Phase Three-Level Flying-Capacitor PFC Rectifier Without Electrolytic Capacitors

A component-minimized and low-voltage-stress single-phase power factor correction rectifier without electrolytic capacitor is proposed in this paper. Component minimization is achieved by embedding an active pulsating-power-buffering (PPB) function within each switching period, such that typical add-on power electronic circuits for PPB are no longer needed. Additionally, with a three-level flying-capacitor configuration, the voltage stresses of switching devices can be reduced more than 50% as compared to existing solutions that are based on embedded PPB. The relationship between the inductance requirement and the patterns of the modulation carriers, and how it can be utilized to minimize the magnetics of the rectifier, is also discussed. A 110 W hardware prototype is designed and tested to demonstrate the feasibilities of the proposed rectifier. An input power factor of more than 0.97, peak efficiency of 95.1%, and an output voltage ripple of less than 4.3% across a wide load range have been experimentally obtained.

An Energy Buffer for Controllable Input Impedance of Constant Power Loads

Power electronic circuits often regulate load power and present a constant power profile to the utility or other electrical source. These constant power loads therefore exhibit a negative incremental input impedance and pose stability challenges when present in either dc or ac systems. This paper presents an energy buffer power converter for a constant power LED lighting load that presents a controllable input impedance to the electrical source. The use of an energy buffer allows the converter to independently control input and output power. The input power is controlled to resemble a resistive load, ensuring that the device exhibits a positive incremental input impedance over short-term input disturbances. Simultaneously, the output power is held constant through high-bandwidth regulation. The control scheme balances the power flow in the long term. Experimental results are presented that demonstrate independence between input and output performance, as well as long-term power balance.

Performance Analysis of Distributed Energy Resource-Based LV Distribution Grid

Distributed energy resources (DERs) are mostly low-power-generating units. In order to augment the energy demands, integration of such energy sources with LV distribution grid is a viable option. A good-quality power from DER ensures safe operation of distribution grid. In this work, an integrated DER consisting of a photovoltaic system, a wind energy conversion system and a micro-hydro system is proposed and coupled to a common DC bus through appropriate power electronic interfacing circuits. A grid interfacing inverter is implemented as an inter-tie between DC-coupled DER and LV distribution grid. The DER supports the DC link voltage of the interfacing inverter. The performance of the distribution grid is examined via connection of a 3-phase nonlinear load onto the distribution grid. The interfacing inverter incorporates the features of DSTATCOM. The effectiveness of DSTATCOM-DER topology in mitigating the power quality problems of nonlinear load is realized through Icosφ control strategy. The results obtained are adequately explained. The quality of power at the point of common coupling is analyzed using total harmonic distortion and total demand distortion and is found to be within IEEE Std. 519-2014. The complete system is modeled and simulated in MATLAB/Simulink.