| 1. |
- Alikhanzadehalamdari, Babak, 1993, et al.
(författare)
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Capacitor and Switch Size Comparisons on High-Power Medium-Voltage DC-DC Converters with Three-Phase Medium-Frequency Transformer
- 2021
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Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 9:3, s. 3331-3338
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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.
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| 2. |
- Augustin, Tim, et al.
(författare)
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Thomson-Coil Actuator System for Enhanced Active Resonant DC Circuit Breakers
- 2022
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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
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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.
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| 3. |
- Colmenares, Juan, 1989-, et al.
(författare)
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Reliability Analysis of a High-Efficiency SiC Three-Phase Inverter
- 2016
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Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : IEEE. - 2168-6777 .- 2168-6785. ; 4:3, s. 996-1006
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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.
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| 4. |
- Gong, H., et al.
(författare)
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Admittance-Dissipativity Analysis and Shaping of Dual-Sequence Current Control for VSCs
- 2022
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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
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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.
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| 5. |
- Harnefors, Lennart, 1968, et al.
(författare)
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Asymmetric Complex-Vector Models with Application to VSC-Grid Interaction
- 2020
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Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - 2168-6777 .- 2168-6785. ; 8:2, s. 1911-1921
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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.
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| 6. |
- Hu, Jian, et al.
(författare)
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Residual Statistics-Based Current Sensor Fault Diagnosis for Smart Battery Management
- 2022
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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
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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).
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| 7. |
- Jin, Lebing, 1988-, et al.
(författare)
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Modulation and Power Losses of a Stacked Polyphase Bridges Converter
- 2017
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Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : IEEE. - 2168-6777 .- 2168-6785. ; 5:1, s. 409-418
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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.
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| 8. |
- Johannesson, Daniel, et al.
(författare)
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Dynamic Avalanche Limit and Current Filamentation Onset Limit in 4H-Silicon Carbide High-Voltage Diodes
- 2021
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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
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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.
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| 9. |
- Li, X., et al.
(författare)
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Adaptive Resilient Secondary Control for Islanded AC Microgrids With Sensor Faults
- 2021
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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
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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.
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| 10. |
- Li, Zejie, et al.
(författare)
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Medium-Voltage Megawatt Power-Electronic-Based Grid Emulators : Testing Capability Requirements and Dynamics Challenges-A Review
- 2024
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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
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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.
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