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1.	Alikhanzadehalamdari, Babak, 1993, et al. (författare) Capacitor and Switch Size Comparisons on High-Power Medium-Voltage DC-DC Converters with Three-Phase Medium-Frequency Transformer 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 9:3, s. 3331-3338 Tidskriftsartikel (refereegranskat)abstract This paper compares the capacitor requirement of selected isolated DC-DC converters for high-power and medium-voltage applications. A numerical comparison is made for a range of switching frequencies and transition times, considering not only the sub-module capacitors of the converters but also the DC-link capacitors. Likewise, a comparison regarding the semiconductor requirement is performed for the converters. Selected inverter topologies to form the dual-active-bridge (DAB) DCDC converter include the two-level converter (2LC), the modular multi-level converter (MMC), the transition arm converter (TAC), the modular transition arm converter (MTAC), and the controlled transition bridge converter (CTB). The results show that conventional DAB requires the minimum capacitor size among the converters. Moreover, in the appropriate operation region, the MTAC-DAB and the CTB-DAB provide the possibility of up to 40% and 60% reduction in the amount of required energy storage compared to the MMC-DAB, respectively. It is also shown that the size of the DC-link capacitors become comparable with the chain-links’ capacitors when the percentage of the transition times per period is reduced to be below 5%. The comparison regarding the semiconductor requirement revealed that the MMC-DAB requires the smallest installed switch power among the multi-level converters.
2.	Augustin, Tim, et al. (författare) Thomson-Coil Actuator System for Enhanced Active Resonant DC Circuit Breakers 2022 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 10:1, s. 800-810 Tidskriftsartikel (refereegranskat)abstract Enhanced active resonant (EAR) dc circuit breakers (DCCBs) are a promising set of recently proposed DCCB concepts. As other DCCBs, EAR DCCBs still require a fast mechanical switch. The requirements on the actuator of the mechanical switch depend on the DCCB concept and the dc grid and are derived here for an EAR DCCB. Thomson-coil actuators (TCAs) can open and close mechanical switches sufficiently fast to satisfy the requirements. This work studies experimentally a TCA system with active damping for an off-the-shelf industrial vacuum interrupter used as mechanical switch in an EAR DCCB. The prototype is explained in detail, and extensive measurement results are presented, showing that active damping must be perfectly timed to be effective. A novel Thomson-coil (TC) driver is proposed and studied experimentally, which operates the TCA more efficiently by recycling energy during the actuation. Moreover, the novel TC driver reduces the capacitive storage by 50% and allows for faster recharging with lower charging current. Finally, the autoreclosing and proactive commutation operation of the TCA system and the interruption capability of the prototype EAR DCCB are demonstrated experimentally.
3.	Colmenares, Juan, 1989-, et al. (författare) Reliability Analysis of a High-Efficiency SiC Three-Phase Inverter 2016 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : IEEE. - 2168-6777 .- 2168-6785. ; 4:3, s. 996-1006 Tidskriftsartikel (refereegranskat)abstract Silicon carbide as an emerging technology offers potential benefits compared with the currently used silicon. One of these advantages is higher efficiency. If this is targeted, reducing the on-state losses is a possibility to achieve it. Parallel-connecting devices decrease the on-state resistance and therefore reduce the losses. Furthermore, increasing the amount of components such as parallel connection of devices introduces an undesired tradeoff between efficiency and reliability, since an increased component count increases the probability of failure. A reliability analysis has been performed on a three-phase inverter rated at 312 kVA, using parallel-connected power modules. This analysis shows that the gate voltage stress has a high impact on the reliability of the complete system. Decreasing the positive gate-source voltage could, therefore, increase the reliability of the system approximately three times without affecting the efficiency significantly. Moreover, adding redundancy in the system could also increase the mean time to failure by approximately five times.
4.	Gong, H., et al. (författare) Admittance-Dissipativity Analysis and Shaping of Dual-Sequence Current Control for VSCs 2022 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 10:1, s. 324-335 Tidskriftsartikel (refereegranskat)abstract This paper analyzes the admittance-dissipativity of dual-sequence current control for grid-connected voltage-source converters (VSCs). The output admittance model of dual-sequence current control is first developed in the stationary reference frame by using complex vectors. Impacts of digital filters used within current control and voltage-feedforward (VFF) control loops, and of the delay compensation at the fundamental frequency, are then evaluated. It is found that the cascaded use of sequence-decomposition filter (SDF) and the low-pass filter (LPF) in the VFF control loop adds a non-dissipative region in the output admittance, and the fundamental-frequency delay-compensation further worsens the dissipativity. An analytical design method for the LPF is then developed to mitigate the non-dissipative region, which lowers the instability risks and improves the stability robustness of dual-sequence current control under different grid conditions. Lastly, simulations and experimental results corroborate theoretical analyses.
5.	Harnefors, Lennart, 1968, et al. (författare) Asymmetric Complex-Vector Models with Application to VSC-Grid Interaction 2020 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 8:2, s. 1911-1921 Tidskriftsartikel (refereegranskat)abstract The properties of complex space-vector models for asymmetric three-phase systems are investigated in this article. Most importantly, three alternative methods for the stability analysis of the asymmetric closed-loop systems are presented. The end results avoid the usage of matrix manipulations. It is shown how the theory can be applied to modeling and stability analysis of a grid-connected voltage-source converter (VSC). The methods are compared using numerical examples.
6.	Hu, Jian, et al. (författare) Residual Statistics-Based Current Sensor Fault Diagnosis for Smart Battery Management 2022 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 10:2, s. 2435-2444 Tidskriftsartikel (refereegranskat)abstract Current sensor fault diagnostic is critical to the safety of lithium-ion batteries (LIBs) to prevent over-charging and over-discharging. Motivated by this, this article proposes a novel residual statistics-based diagnostic method to detect two typical types of sensor faults, leveraging only the 50 current-voltage samples at the startup phase of the LIB system. In particular, the load current is estimated by using particle swarm optimization (PSO)-based model matching with measurable initial system states. The estimation residuals are analyzed statistically with Monte-Carlo simulation, from which an empirical residual threshold is generated and used for accurate current sensor fault diagnostic. The residual evaluation process is well proved with high robustness to the measurement noises and modeling uncertainties. The proposed method is validated experimentally to be effective in current sensor fault diagnosis with low miss alarm rate (MAR) and false alarm rate (FAR).
7.	Jin, Lebing, 1988-, et al. (författare) Modulation and Power Losses of a Stacked Polyphase Bridges Converter 2017 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : IEEE. - 2168-6777 .- 2168-6785. ; 5:1, s. 409-418 Tidskriftsartikel (refereegranskat)abstract This paper presents and analyzes modulation and power losses of a stacked polyphase bridges converter - a modular topology potentially allowing increased compactness and fault tolerance for automotive drive systems. In particular, an analysis of the impact of modulation on the harmonic content of the dc-link current of the converter is made. Due to the possibility of using higher switching frequency devices, the current ripple of the stacked polyphase bridges converter can be smaller than that of the two-level three-phase converter with the same dclink capacitor. However, higher switching frequency will result in higher switching losses per fundamental period. Therefore, this paper also investigates the reduction in the dc-link ripple current achieved by interleaving the modulation between the different converter submodules. The amount of reduction can be predicted using an analytical model whose results are demonstrated to be in good agreement with results from corresponding simulations and from an experimental setup. Furthermore, based on the experimentally verified analysis, the stacked polyphase bridges converter in a typical automotive drive system is discussed and compared to a conventional two-level three-phase converter.
8.	Johannesson, Daniel, et al. (författare) Dynamic Avalanche Limit and Current Filamentation Onset Limit in 4H-Silicon Carbide High-Voltage Diodes 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; , s. 1-1 Tidskriftsartikel (refereegranskat)abstract Dynamic avalanche (DA) phenomena and current filament (CF) formation are two extreme conditions observed in high-power devices, setting the maximum limit on turn-on/off current capability and di/dt in Silicon-based bipolar devices. The properties of the Silicon Carbide (SiC) material enable devices with increased resilience for DA and CF compared to Si counterparts, and thus the SOA limits may be extended. In this study, the limit of DA and CF in SiC-based semiconductor structures are investigated by numerical TCAD simulations, for different current levels, di/dt, and temperatures for high-voltage devices (e.g., 20 kV class). DA is first indicated for di/dt beyond 105 kA/μs for current densities in the range of 50–1000 A/cm2, at 448 K. Similarly, stray inductance induced avalanche conditions are initiated above 33 kA/μs, while CF is initiated for di/dt starting from 83 kA/μs for current densities in the range of 8.3 kA/cm2. Moreover, the effects of the stray inductance in the main circuit loop are studied which may cause critical voltage transients during certain operating conditions. The outcome of the study may be useful to determine safe-operating-area limits and to be used as input for power electronic converter design as well as gate driver design for high-power electronic systems.
9.	Li, X., et al. (författare) Adaptive Resilient Secondary Control for Islanded AC Microgrids With Sensor Faults 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 9:5, s. 5239-5248 Tidskriftsartikel (refereegranskat)abstract In this article, we investigate the adaptive resilient secondary voltage and frequency control problem for islanded ac microgrids (MG) in the presence of sensor faults. Sensor faults or data attacks have a great impact on the stability and quality of MG. Existing methods commonly assume that the sensing information from distributed generations (DGs) is healthy or satisfies some ideal conditions. To achieve resilient secondary voltage restoration, a novel adaptive fault tolerant control scheme is proposed. Since the bounds of the time-varying faults are unknown, sufficient conditions are first derived to guarantee the voltage tracking errors to be uniformly ultimately bounded. It is also theoretically shown that the frequency restoration and power sharing can be ensured stable of the overall ac MG system by using the same control scheme. Compared with the existing distributed control methods for secondary control of MG, the considered problem with unknown boundaries sensor faults is more challenging and still not well explored.
10.	Li, Zejie, et al. (författare) Medium-Voltage Megawatt Power-Electronic-Based Grid Emulators : Testing Capability Requirements and Dynamics Challenges-A Review 2024 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 12:2, s. 1545-1559 Tidskriftsartikel (refereegranskat)abstract Power-electronic-based grid emulators are emerging as a promising way to test the grid-code compliance of renewable energy resources. Yet, the ever-increasing power and voltage levels of device under test (DUT) pose new requirements and challenges to power-electronic-based grid emulators. This article first gives an overview of testing capability requirements based on the recent grid codes and standards and then discusses the resulted dynamic interactions and solutions for power-electronic-based grid emulators. Perspectives on the open issues and emerging trends of grid emulators are finally shared.
11.	Li, Zejie, et al. (författare) Power-Hardware Design and Topologies of Converter-Based Grid Emulators for Wind Turbines 2023 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 11:5, s. 5001-5017 Tidskriftsartikel (refereegranskat)abstract Power-electronic-based grid emulators (GEs) emerge as a favorable method for testing grid-code compliances of wind turbines (WTs), thanks to their full controllability and improved efficiency. To accommodate the increasing power and voltage levels of WTs, scalability becomes a critical requirement for the topologies of converter-based GEs. This article identifies first the power rating of future GEs based on the system architecture and the evolution of WTs, followed by evaluating converter topologies of GEs for high scalability. Design considerations of power semiconductor devices, step-up transformers, dc chopper, and dc capacitors are also discussed for existing and prospective GEs.
12.	Malik, Naveed-ur-Rehman, et al. (författare) Dynamic and Steady-State 3-D Thermal Design and Investigation of the Rotating Power Electronic IGBT Converter 2016 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 4:2, s. 679-688 Tidskriftsartikel (refereegranskat)abstract This paper deals with a 3-D development of a thermal model of a power electronic converter mounted on the generator shaft and rotating with it. The dimensions of the heat sink are determined, and the temperature gradients of the converter, its heat sink, and shaft during natural and forced convection are analyzed for variable rotor speeds. It is shown that the chosen sizes of the insulated gate bipolar transistor (IGBT) and the heat sink offer a compact design of the rotating converter, which is sufficient for its mounting in limited space offered by the generator shaft. Furthermore, a transient temperature profile is also presented. In addition, a transient thermal profile of the converter and dimensions of the cooling fan are also calculated. Besides, the analysis of the cooling requirements of the converter during over-currents due to grid faults is also investigated.
13.	Mohanty, Rabindra, 1989, et al. (författare) A Cosine Similarity Based Centralized Protection Scheme for DC Microgrids 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 9:5, s. 5646-5656 Tidskriftsartikel (refereegranskat)abstract Unlike the phasor measurement based protection in AC systems, the protection of DC systems deals with complex fault transients which mandates the isolation of the faulted segment within few milliseconds as continued fault current leads to overheating issue in power electronic converters. To this end, several works have been suggested based on unit and nonunit protections for DC microgrids. Threshold selection and protection coordination are the challenges associated with nonunit protection. Similarly, communication delay and link failure limit the application of unit protection. To address these issues, this paper presents a robust centralized protection scheme for DC microgrids, which is resilient to communication delay and link failure. It uses current of each line segment to compute the similarity of current change at both ends of the line segment to derive the protection decision. To overcome the communication failure from one end of the line segment or even from multiple segments, the proposed method uses data from adjacent segments to derive the protection decision correctly. Using PSCAD/EMTDC environment, the performance of the proposed method is evaluated for various cases and compared with available techniques. Finally, the accuracy of the protection algorithm is validated under experimental conditions.
14.	Nogales, Connor, et al. (författare) An 800W Four-Level Supply Modulator for Efficient Envelope Tracking of RF Transmitters 2023 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 11:3, s. 3251-3260 Tidskriftsartikel (refereegranskat)abstract Modern RF communication and electronic warfare applications require systems capable of amplifying signals with high bandwidths and high peak to average power ratios (PAPR). One technique used to meet these demands is supply modulation also known as envelope tracking where the drain voltage of the power amplifier (PA) is dynamically changed according to the signal envelope. The limiting factor with supply modulation is typically the efficiency and switching speed of the power converter. The power converter must also be capable of producing high power levels when supplying an array of PA units or a single high power transmitter. This paper demonstrates the design and characterization of a four-level discrete supply modulator with a peak output power of 800W operating at a maximum switching frequency of 10MHz. The modulator switches between four discrete voltages from 10 to 20V. GaN on silicon HEMT power transistors are selected for the switching devices after conducting a survey of commercially available silicon MOSFET, silicon-carbide MOSFET, and GaN on silicon power transistors. Trace interconnect models are developed to achieve accurate predictions of the time domain waveforms, including ringing at the switching edges. These interconnects are first analyzed using full-wave electromagnetic simulations, and then modeled with RLC networks suitable for time domain simulations. For a test signal with equal duty cycle between the four levels, an efficiency greater than 94.0% is demonstrated for average output powers exceeding 91.6W. When tracking the envelope of an 8MHz 64-QAM signal, an average efficiency of 93.5% is achieved providing a peak power of 800W.
15.	Qazi, Fahad, et al. (författare) Passive SC Sigma Delta Modulators Revisited : Analysis and Design Study 2015 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : IEEE Press. - 2168-6777 .- 2168-6785. ; 5:4, s. 624-637 Tidskriftsartikel (refereegranskat)abstract In this paper we study passive switch-capacitor sigma-delta (ΣΔ) modulators suitable for low power applications. Using a one-bit quantizer as the only active block those modulators save power and achieve high linearity. However, their order is largely limited since the passive loop filter presents a significant attenuation to the signal. Typically with a secondorder filter the modulator can achieve a satisfactory signal-toquantization-noise ratio (SQNR) by using a large enough oversampling (OSR) that also creates a tradeoff with the power consumption. A passive ΣΔ modulator when modeled as a linear system requires extraction of the equivalent loop gain. It is shown that for this purpose the quantization and thermal noise should be considered jointly. The paper presents optimization of the modulator in the design space defined by the filter capacitor ratios and the feedback coefficients. Included is a detailedanalysis of the thermal noise, quantization noise, and other parasitic effects. The discussion is supported by 65 nm CMOS chip measurements showing power consumption < 0.62μW, SNDR = 73 dB, and energy efficiency < 0.17 pJ/step.
16.	Qin, Haihong, et al. (författare) A Comparative Study of Freewheeling Methods for eGaN HEMTs in a Phase-leg Configuration 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 9:3, s. 3657-3670 Tidskriftsartikel (refereegranskat)abstract Enhancement Gallium nitride high-electron mobility transistors (eGaN HEMTs) have been developed with lower conduction losses and higher switching speed compared to MOSFETs. Self-commutated reverse conduction (SCRC) mechanism determines no reverse recovery phenomenon but larger reverse conduction voltage drop of eGaN HEMTs than the body diodes in traditional Si MOSFETs or other freewheeling diodes. To reduce the large reverse conduction loss of eGaN HEMTs, the performance of different freewheeling methods for eGaN HEMTs in a phase-leg configuration is compared in this paper. Firstly, the reverse conduction mechanism and characteristics of eGaN HEMTs are analyzed. Then, four freewheeling ways for eGaN HEMTs are introduced, and the equivalent circuits are also given and analyzed. A double pulse test platform is established to further explore the influence of the freewheeling ways on the conduction and switching characteristics. Finally, the total losses of a phase-leg configuration with different freewheeling ways based on a buck converter is analyzed and compared. The paper aims to give a guidance to properly select freewheeling ways for eGaN HEMTs under different operation conditions.
17.	Sadik, Diane-Perle, et al. (författare) Analysis of Parasitic Elements of SiC Power Modules With Special Emphasis on Reliability Issues 2016 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : IEEE. - 2168-6777 .- 2168-6785. ; 4:3, s. 988-995 Tidskriftsartikel (refereegranskat)abstract Commercially available silicon carbide (SiC) MOSFET power modules often have a design based on existing packages previously used for silicon insulated-gate bipolar transistors. However, these packages are not optimized to take advantage of the SiC benefits, such as high switching speeds and high-temperature operation. The package of a half-bridge SiC MOSFET module has been modeled and the parasitic elements have been extracted. The model is validated through experiments. An analysis of the impact of these parasitic elements on the gate-source voltage on the chip has been performed for both low switching speeds and high switching speeds. These results reveal potential reliability issues for the gate oxide if higher switching speeds are targeted.
18.	Wu, Yixuan, 1993-, et al. (författare) Open-Phase Fault Tolerant Pole Transition Control of an Asynchronous Variable-Pole Machine Using Harmonic Plane Decomposition 2024 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; , s. 1-1 Tidskriftsartikel (refereegranskat)abstract Automotive applications are revisiting the use of induction machines as magnet-free propulsive solutions due to theirintrinsic robustness and reliability. Special multiphase configurations are under investigation to reduce the losses further andfulfill the stringent energy-efficiency and compactness requirements of the automotive industry. One of these configurations isknown as variable-pole machines, which allows the number ofmagnetic pole pairs to change on the fly. These machines canstretch the torque-speed operating region, exploit the maximumtorque capability, and exhibit competitive efficiency. Althoughfault tolerance has been widely explored for multiphase machines,the same cannot be said for variable-pole machines because,until recently, complete models to describe their dynamics under any condition, including magnetic pole changing and faultoccurrences, were unavailable. This paper presents a post-faultcontrol strategy for variable-pole machines with an open-phasefault, which can operate during pole changing and addressesthe issue of fault-tolerant operation. The effectiveness of thecontrol system is verified by experimental tests carried out withan eighteen-phase variable-pole induction machine prototype.
19.	Xie, Haotian, et al. (författare) Iterative Gradient Descent Based Finite Control Set Predictive Current Control with Least Squares Optimized Duty Cycles 2022 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 10:2, s. 1422-1433 Tidskriftsartikel (refereegranskat)abstract Finite Control Set Predictive Current Control (FCS-PCC) is widely recognized as a competitive control strategy in the field of electrical drives, due to its superiority of fast dynamic response and low switching frequency. However, FCS-PCC is penalized by its inherent drawback that the discrete nature of switching states leads to relatively high torque and current deviations. In this paper, an iterative gradient descent method combined with least squares optimized duty cycles is presented to improve the steady-state performance of FCS-PCC. Unlike the cost function optimization in the conventional FCS-PCC, the quadratic programming problem is solved from a geometric perspective, by obtaining the gradient descent which minimizes the tracking deviation in the fastest manner. To synthesize the gradient descent, the optimal stator current derivatives in the current and previous iteration are employed, and their duty cycles are determined by the least squares method. The abovementioned procedures are iteratively repeated in the dichotomy-based periods. The experimental performance of the proposed gradient descent based FCS-PCC is verified at a 8 kHz sampling frequency, which is compared with that of conventional and dichotomy-based FCS-PCC. It is validated that the proposed algorithm outperforms the conventional and dichotomy-based FCS-PCC at both the steady-state and transient state.
20.	Xiong, Binyu, et al. (författare) Peak Power Estimation of Vanadium Redox Flow Batteries Based on Receding Horizon Control 2023 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 11:1, s. 154-165 Tidskriftsartikel (refereegranskat)abstract The peak power of a vanadium redox flow battery (VRB) reflects its capability to continuously absorb or release energy. Accurate estimation of peak power is essential for the safe, reliable, and efficient operation of VRB systems, but also challenging as it is limited by various factors, such as currents, flow rates, temperature, and state of charge. This article proposes a new online model-based peak power estimation scheme for VRBs. First, the model parameters and system states are accurately estimated using the recursive least squares with forgetting and the unscented Kalman filter, respectively. Next, based on a linear time-varying VRB model and the estimated states, the peak power estimation is formulated into an optimal control problem, and the problem is solved using the receding horizon control (RHC). The influence of the predictive horizon on the estimated peak power is discussed. Finally, the effectiveness of the proposed RHC-based peak power estimation scheme is experimentally verified on a 5-kW/3-kWh VRB platform.
21.	Xu, Qianwen, 1992-, et al. (författare) Review on Advanced Control Technologies for Bidirectional DC/DC Converters in DC Microgrids 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 9:2, s. 1205-1221 Tidskriftsartikel (refereegranskat)abstract DC microgrids encounter the challenges of constant power loads (CPLs) and pulsed power loads (PPLs), which impose the requirements of fast dynamics, large stability margin, high robustness that cannot be easily addressed by conventional linear control methods. This necessitates the implementation of advanced control technologies in order to significantly improve the robustness, dynamic performance, stability and flexibility of the system. This article presents an overview of advanced control technologies for bidirectional dc/dc converters in dc microgrids. First, the stability issue caused by CPLs and the power balance issue caused by PPLs are discussed, which motivate the utilization of advanced control technologies for addressing these issues. Next, typical advanced control technologies including model predictive control, backstepping control, sliding-mode control, passivity-based control, disturbance estimation techniques, intelligent control, and nonlinear modeling approaches are reviewed. Then the applications of advanced control technologies in bidirectional dc/dc converters are presented for the stabilization of CPLs and accommodation of PPLs. Finally, advanced control techniques are explored in other high-gain nonisolated (e.g., interleaved, multilevel, cascaded) and isolated converters (e.g., dual active bridge) for high-power applications.
22.	Yang, Zhiqing, et al. (författare) Wideband Dissipativity Enhancement for Grid-Following VSC Utilizing Capacitor Voltage Feedforward 2023 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 11:3, s. 3138-3151 Tidskriftsartikel (refereegranskat)abstract Frequency-domain dissipativity of the converter admittance provides an intuitive approach to analyze wideband resonances due to the interactions with the grid. Although the reasons for high- and low-frequency resonances are different, it is found that the proportional capacitor voltage feedforward (CVF) can affect and reshape the converter admittance in a wide frequency range. To enhance wideband dissipativity under a weak/capacitive grid, a proportional-integral (PI)-derivative CVF is proposed in this article. Specifically, high-frequency dissipativity can be guaranteed through the multisampling control (MSC) with proportional-derivative CVF. The low-frequency nondissipative region caused by the phase-locked loop (PLL) and proportional CVF can be compensated through multiorder integrations. In light of grid frequency disturbances, modified integrators are further proposed for the multiorder integrations. The proposed method also applies to the conventional double-sampling control (DSC) with regard to the low-frequency dissipativity enhancement. Finally, experiments validate the proposed control method.
23.	Zhang, Daifei, et al. (författare) Detailed Modeling and In-Situ Calorimetric Verification of Three-Phase Sparse NPC Converter Power Semiconductor Losses 2023 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 11:3, s. 3409-3423 Tidskriftsartikel (refereegranskat)abstract The three-phase (3- Φ) three-level (3-L) sparse neutral point clamped converter (SNPCC) combines a 3-L matrix stage and a 3- Φtwo-level (2-L) inverter stage to generate 3-L switched output voltages with a reduced transistor count (10 instead of 12 or 18) compared with the classical 3-L NPCC or 3-L active NPCC structure, targeting variable-speed drive (VSD) systems with low ripple of the motor phase currents or bidirectional 3- Φ power factor correcting (PFC) rectifier systems with reduced boost inductor volume. This article analyzes and experimentally characterizes the performance of an IGBT-based 3- Φ 3-L SNPCC and describes, for the first time, a hybrid current commutation effect between inverter-stage diodes and matrix-stage IGBTs that occurs when operating with lower modulation indices and leads to increased switching losses (up to 20% ). The proposed new semiconductor loss modeling approach accounts for this effect successfully, which is verified ( < 10% error) on an 800- Vdc, 7.5-kW SNPCC hardware demonstrator using a new in-situ calorimetric method that facilitates accurate stage-level semiconductor loss measurements. Heat spreading effects caused by the asymmetrical losses injection and thermal decoupling between two in-situ loss measurement blocks are carefully checked with finite-element method (FEM) simulations. Furthermore, an experimental evaluation of common-mode (CM) and differential-mode (DM) high-frequency (HF) voltage-time area ripples (as a generic measure for the required filtering effort) for three typical symmetrical and asymmetrical modulation switching state sequences is provided together with the semiconductor loss characterization. Utilizing a low-switching-loss asymmetric modulation scheme that operates the 3-L matrix stage and the 2-L inverter stage with the effective switching frequencies of 16 kHz and 5.3 kHz, respectively, the 3-L SNPCC demonstrator finally achieves a high rated power (7.5 kW, load current phase shift φ = 0 ) semiconductor efficiency of 98.8%.
24.	Zhang, Hongyang, et al. (författare) Loop-at-a-Time Stability Analysis for Grid-Connected Voltage-Source Converters 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 9:5, s. 5807-5821 Tidskriftsartikel (refereegranskat)abstract The instability phenomena caused by converter–grid interactions can be prevented by designing controllers with adequate stability margins. Yet, the multiple-input–multiple-output (MIMO) dynamics of grid-connected voltage-source converters (VSCs) complicate the stability analysis for the controller design. To tackle this challenge, this article presents a loop-at-a-time stability analysis for grid-connected VSCs, which not only shows close correlations with the generalized Nyquist criterion for MIMO systems but also enables to quantify the stability margins of individual closed loops. Moreover, the interactions between the closed loops can be analyzed. Test cases with numerical sensitivity analysis, simulations, and field measurements of a converter validate the theory.
25.	Zhao, Fangzhou, et al. (författare) Low-Frequency Passivity-Based Analysis and Damping of Power-Synchronization Controlled Grid-Forming Inverter 2023 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 11:2, s. 1542-1554 Tidskriftsartikel (refereegranskat)abstract This article presents a passivity-based analysis and damping method for the low-frequency dynamics of grid-forming (GFM) control. A closed-form analytical solution to the positive realness of control input admittance is developed, which reveals the inherent nonpassive property of GFM control. This feature gives rise to the risk of instability, especially in connection with a nearby nonpassive GFM inverter, which may induce undesired control interactions. It is further revealed that the passivity index is determined by a low-frequency resonance around 10 Hz in the dq -frame, and this resonance can be better dampened, therefore, with enhanced passivity index, by using a virtual reactance (VRA) than using a virtual resistance (VRS). Finally, the theoretical findings are verified by the experimental results.
26.	Zhao, Zhengming, et al. (författare) In Praise of JESTPE Associate Editors-Part IV 2021 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 9:6, s. 6455-6459 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Adefining component that makes the Journal of Emerging and Selected Topics in Power Electronics (JESTPE) a predominant publication in the field of power electronics is our past and current associate editors. Although they are largely hidden and unheard until papers they recommend for publication appear in print, the efforts of our associate editors are extremely important in producing the JESTPE for the readers. The tasks of an associate editor include reading the submissions, finding competent reviewers, reading the comments from the reviewers, and making recommendations to the assigned editors, all of which are to be accomplished in a timely manner. In some cases, associate editors expend lots of time contacting busy reviewers to submit their comments, making recommendations, and addressing rejected paper complaints from the authors.
27.	Ahmed, Noman, et al. (författare) A computationally efficient continuous model for the modular multilevel converter 2014 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : IEEE. - 2168-6777. ; 2:4, s. 1139-1148 Tidskriftsartikel (refereegranskat)abstract Simulation models of the modular multilevel converter (MMC) play a very important role for studying the dynamic performance. Detailed modeling of the MMC in electromagnetic transient simulation programs is cumbersome, as it requires high computational effort and simulation time. Several averaged or continuous models proposed in the literature lack the capability to describe the blocked state. This paper presents a continuous model, which is capable of accurately simulating the blocked state. This feature is very important for accurate simulation of faults. The model is generally applicable, although it is particularly useful in high-voltage dc applications.
28.	Zhao, Shuang, et al. (författare) Off-Vehicle Evaluation of Active Oscillation Damping Schemes 2014 Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777. ; 2:2, s. 264-271 Tidskriftsartikel (refereegranskat)abstract Torsional drivetrain oscillations are a well-known problem in electrical or hybrid electric drivetrains and may greatly influence the driving comfort. An experimental testing setup that can be used to design and evaluate active oscillation damping schemes is proposed in this paper. Instead of an in-vehicle test, the drivetrain transmission is emulated from mathematic models, executed by a servo drive which is connected to the physical electrical drive system. The proposed setup functions as a hardware-in-the-loop simulator and can be easily adjusted to simulate any drive trains without additional cost.

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