Showing papers in "IEEE Transactions on Power Electronics in 2022"
TL;DR: In this article, the authors classify, describe, and critically compare different modeling techniques and control methods for dual-active-bridge (DAB) dc-dc converters and provide explicit guidance about the DAB controller design to practicing engineers and researchers.
Abstract: This article classifies, describes, and critically compares different modeling techniques and control methods for dual-active-bridge (DAB) dc–dc converters and provides explicit guidance about the DAB controller design to practicing engineers and researchers. First, available modeling methods for DAB including reduced-order model, generalized average model, and discrete-time model are classified and quantitatively compared using simulation results. Based on this comparison, recommendations for suitable DAB modeling method are given. Then, we comprehensively review the available control methods including feedback-only control, linearization control, feedforward plus feedback, disturbance-observer-based control, feedforward current control, model predictive current control, sliding mode control, and moving discretized control set model predictive control. Frequency responses of the closed-loop control-to-output and output impedance are selected as the metrics of the ability in voltage tracking and the load disturbance rejection performance. The frequency response plots of the closed-loop control-to-output transfer function and output impedance of each control method are theoretically derived or swept using simulation software PLECS and MATLAB. Based on these plots, remarks on each control method are drawn. Some practical control issues for DAB including dead-time effect, phase drift, and dc magnetic flux bias are also reviewed. This article is accompanied by PLECS simulation files of the reviewed control methods.
117 citations
TL;DR: In this article , the authors consider the most relevant contributions published in the last decade, mainly focusing on three relevant issues: weighting factor calculation when multiple objectives are utilized in the cost function, current/torque harmonic distortion optimization when the power converter switching frequency is reduced, and robustness improvement under parameters uncertainties.
Abstract: The application of model predictive control in electrical drives has been studied extensively in the past decade. This article presents what the authors consider the most relevant contributions published in the last years, mainly focusing on three relevant issues: weighting factor calculation when multiple objectives are utilized in the cost function, current/torque harmonic distortion optimization when the power converter switching frequency is reduced, and robustness improvement under parameters uncertainties. Therefore, this article aims to enable readers to have a more precise overview while facilitating their future research work in this exciting area.
68 citations
TL;DR: In this article , the authors classify, describe, and critically compare different modeling techniques and control methods for dual-active-bridge (DAB) dc-dc converters and provide explicit guidance about the DAB controller design to practicing engineers and researchers.
Abstract: This article classifies, describes, and critically compares different modeling techniques and control methods for dual-active-bridge (DAB) dc–dc converters and provides explicit guidance about the DAB controller design to practicing engineers and researchers. First, available modeling methods for DAB including reduced-order model, generalized average model, and discrete-time model are classified and quantitatively compared using simulation results. Based on this comparison, recommendations for suitable DAB modeling method are given. Then, we comprehensively review the available control methods including feedback-only control, linearization control, feedforward plus feedback, disturbance-observer-based control, feedforward current control, model predictive current control, sliding mode control, and moving discretized control set model predictive control. Frequency responses of the closed-loop control-to-output and output impedance are selected as the metrics of the ability in voltage tracking and the load disturbance rejection performance. The frequency response plots of the closed-loop control-to-output transfer function and output impedance of each control method are theoretically derived or swept using simulation software PLECS and MATLAB. Based on these plots, remarks on each control method are drawn. Some practical control issues for DAB including dead-time effect, phase drift, and dc magnetic flux bias are also reviewed. This article is accompanied by PLECS simulation files of the reviewed control methods.
67 citations
TL;DR: In this paper , a data-driven method based on the random partial charging process and sparse Gaussian process regression (GPR) is proposed in order to solve the problems of battery safety monitoring, residual value assessment, and predictive maintenance.
Abstract: The rapid development of battery technology has promoted the deployment of electric vehicles (EVs). To ensure the healthy and sustainable development of EVs, it is urgent to solve the problems of battery safety monitoring, residual value assessment, and predictive maintenance, which heavily depends on the accurate state-of-health (SOH) estimation of batteries. However, many published methods are unsuitable for actual vehicle conditions. To this end, a data-driven method based on the random partial charging process and sparse Gaussian process regression (GPR) is proposed in this article. First, the random capacity increment sequences (△Q) at different voltage segments are extracted from the partial charging process. The average value and standard deviation of △Q are used as features to indicate battery health. Second, correlation analysis is conducted for three types of batteries, and high correlations between the features and battery SOH are verified at different temperatures and discharging current rates. Third, by using the proposed features as inputs, sparse GPR models are constructed to estimate the SOH. Compared with other data-driven methods, the sparse GPR has the highest estimation accuracy, and its average maximum absolute errors are only 2.88%, 2.52%, and 1.51% for three different types of batteries, respectively.
62 citations
TL;DR: An online multifault diagnosis strategy based on the fusion of model-based and entropy methods is proposed to detect and isolate multiple types of faults, including current, voltage, and temperature sensor faults, short-circuit faults, and connection faults.
Abstract: Various faults in the lithium-ion battery system pose a threat to the performance and safety of the battery. However, early faults are difficult to detect, and false alarms occasionally occur due to similar features of the faults. In this article, an online multifault diagnosis strategy based on the fusion of model-based and entropy methods is proposed to detect and isolate multiple types of faults, including current, voltage, and temperature sensor faults, short-circuit faults, and connection faults. An interleaved voltage measurement topology is adopted to distinguish voltage sensor faults from battery short-circuit or connection faults. Based on the established comprehensive battery model, structural analysis is performed to develop diagnostic tests that are sensitive to different faults. Residual generation based on the extended Kalman filter and residual evaluation based on the statistical inference are conducted to detect and isolate sensor faults. Sample entropy is used to further distinguish between the short-circuit faults and connection faults. The effectiveness of the proposed diagnostic method is verified by multiple fault tests with different fault types and sizes. The results also show that the proposed method has good robustness to noise and inconsistencies in the state of charge and temperature.
53 citations
TL;DR: In this article, a novel fusion-based SOH estimator is proposed, which combines an open circuit voltage (OCV) model and the incremental capacity analysis, and the extracted model FOI and IC morphological FOIs are further fused for SOH estimation through an artificial neural network.
Abstract: The state of health (SOH) is a vital parameter enabling the reliability and life diagnostic of lithium-ion batteries. A novel fusion-based SOH estimator is proposed in this study, which combines an open circuit voltage (OCV) model and the incremental capacity analysis. Specifically, a novel OCV model is developed to extract the OCV curve and the associated features-of-interest (FOIs) from the measured terminal voltage during constant-current charge. With the determined OCV model, the disturbance-free incremental capacity (IC) curves can be derived, which enables the extraction of a set of IC morphological FOIs. The extracted model FOI and IC morphological FOIs are further fused for SOH estimation through an artificial neural network. Long-term degradation data obtained from different battery chemistries are used for validation. Results suggest that the proposed fusion-based method manifests itself with high estimation accuracy and high robustness.
51 citations
TL;DR: In this paper, the authors implemented beveled-mesa NiO/Ga2O3 p-n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, achieving high conversion efficiency of 98.5% with 100-min stable operating capability.
Abstract: The technical progress of Ga2O3 power diodes is now stuck at a critical point where a lack of performance evaluation and reliability validation at the system-level applications seriously limits their further development and even future commercialization. In this letter, by implementing beveled-mesa NiO/Ga2O3 p–n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, high conversion efficiency of 98.5% with 100-min stable operating capability has been demonstrated. In particular, rugged reliability is validated after over 1 million times dynamic breakdown with a 1.2-kV peak overvoltage. Meanwhile, superior device performance is achieved, including a static breakdown voltage (BV) of 1.95 kV, a dynamic BV of 2.23 kV, a forward current of 20 A (2 kA/cm2 current density), and a differential specific on -resistance of 1.9 mΩ·cm2. These results indicate that Ga2O3 power HJDs are developing rapidly with their own advantages, presenting the enormous potential in high-efficiency, high-power, and high-reliability applications.
49 citations
TL;DR: In this paper , the authors present the application of model predictive control (MPC) in high-performance drives and compare MPC with classical control techniques such as field-oriented control and direct torque control.
Abstract: This article presents the application of model predictive control (MPC) in high-performance drives. A wide variety of machines have been considered: Induction machines, synchronous machines, linear motors, switched reluctance motors, and multiphase machines. The control of these machines has been done by introducing minor and easy-to-understand modifications to the basic predictive control concept, showing the high flexibility and simplicity of the strategy. The second part of the article is dedicated to the performance comparison of MPC with classical control techniques such as field-oriented control and direct torque control. The comparison considers the dynamic behavior of the drive and steady-state performance metrics, such as inverter losses, current distortion in the motor, and acoustic noise. The main conclusion is that MPC is very competitive concerning classic control methods by reducing the inverter losses and the current distortion with comparable acoustic noise.
48 citations
TL;DR: In this paper , a p-NiO junction termination extension (JTE) and a small-angle beveled field plate (BFP) are proposed to improve the performance of heterojunction diodes.
Abstract: In this letter, high-performance p-NiO/ β -Ga 2 O 3 heterojunction diodes (HJDs) with composite terminal structures, a p-NiO junction termination extension (JTE), and a small-angle beveled field plate (BFP) are demonstrated. By implementing a p-NiO JTE structure, the optimal breakdown voltage ( V br ) of β -Ga 2 O 3 HJD increases from 955 to 1945 V, and the integration of the small-angle BFP further boosts the breakdown voltage up to 2410 V. An 80-nm thin p-NiO layer is adopted in the heterojunction to reduce the specific on -resistance ( R on,sp ), while the composite terminal structures have little effect on R on,sp , due to the super-large lateral spread resistance. The β -Ga 2 O 3 HJD with composite terminal structures achieves a low R on,sp of 1.12 mΩ·cm 2 , yielding the highest direct-current Baliga's figure-of-merit (FOM = V br 2 / R on,sp ) among all reported β-Ga 2 O 3 diodes with a value of 5.18 GW/cm 2 , which is about 15% of the theoretical value. These results suggest that the electrical field engineering with a composite terminal structure is a viable and effective technological strategy to enable the realization of β -Ga 2 O 3 bipolar power rectifiers.
43 citations
TL;DR: This work proposes an augmented prediction model based on a state observer that includes as many harmonic components as necessary to accurately represent the output current, improving the system performance.
Abstract: A finite control set model predictive control (FCS-MPC) strategy consists of a prediction model, a cost function and an optimization algorithm. Consequently, the performance of the FCS-MPC depends on the proper design of these three elements. This article assesses the influence of the prediction model of an uninterruptible power supply (UPS). Since the load connected to the voltage source inverter (VSI) affects the dynamic of the system state variables, the load dynamic should be included in the system model. This makes the design of the prediction model a challenge because the load connected to the VSI is generally unknown. To deal with this uncertainty, this work proposes an augmented prediction model based on a state observer that includes as many harmonic components as necessary to accurately represent the output current. The performance of the FCS-MPC for a UPS is evaluated in a laboratory prototype using the proposed and the conventional prediction models. Experimental results show that the proposed solution provides a more accurate representation of the output current, improving the system performance.
41 citations
TL;DR: Li et al. as discussed by the authors proposed a multistage SOH estimation method with a broad scope of applications, including the unfavorable but practical scenarios of heavily partial charging, and extracted different sets of health indicators (HIs), covering both the morphological incremental capacity features and the voltage entropy information, from the partial constant-current charging data with different initial charging voltages to characterize the aging status.
Abstract: State of health (SOH) is critical to the management of lithium-ion batteries (LIBs) due to its deep insight into health diagnostic and protection. However, the lack of complete charging data is common in practice, which poses a challenge for the charging-based SOH estimators. This article proposes a multistage SOH estimation method with a broad scope of applications, including the unfavorable but practical scenarios of heavily partial charging. In particular, different sets of health indicators (HIs), covering both the morphological incremental capacity features and the voltage entropy information, are extracted from the partial constant-current charging data with different initial charging voltages to characterize the aging status. Following this endeavor, artificial neural network based HI fusion is proposed to estimate the SOH of LIB precisely in real time. The proposed method is evaluated with long-term aging experiments performed on different types of LIBs. Results validate several superior merits of the proposed method, including high estimation accuracy, high tolerance to partial charging, strong robustness to cell inconsistency, and wide generality to different battery types.
TL;DR: This letter presents a new low-voltage direct-current fault current bypass-based solid-state circuit breaker (SSCB) using silicon-carbide mosfets that provides the possibility to select the clamping voltage of metal–oxide varistors close to the nominal voltage of the dc system.
Abstract: This letter presents a new low-voltage direct-current fault current bypass-based solid-state circuit breaker (SSCB) using silicon-carbide mosfet s. The proposed SSCB provides the possibility to select the clamping voltage of metal–oxide varistors (MOVs) close to the nominal voltage of the dc system. This reduces voltage overshoots across the main switch and snubber components and extends the maximum allowable dc bus voltage on the SSCB. The MOVs are removed from the power line, and their leakage currents are completely eliminated. The clamping voltage of the MOV and its surge energy rating is considered to optimize the MOV. The dv/dt across the main switchis controlled by an auxiliary capacitor, where a design procedure is presented to optimize its value. Also, the stored inductive energy of the line inductor in dc systems is bypassed using an auxiliary branch and prevented from flowing through the faulty section to enhance the safety. LTspice simulations are presented to show the significance of the proposed SSCB. The experiments of 375 V/170 A/2.4 μs and 600 V/163 A/2.4 μs verify the effectiveness of the proposed design in practice.
DOI•
TL;DR: Li et al. as discussed by the authors proposed a multistage SOH estimation method with a broad scope of applications, including the unfavorable but practical scenarios of heavily partial charging, and extracted different sets of health indicators (HIs), covering both the morphological incremental capacity features and the voltage entropy information, from the partial constant-current charging data with different initial charging voltages to characterize the aging status.
Abstract: State of health (SOH) is critical to the management of lithium-ion batteries (LIBs) due to its deep insight into health diagnostic and protection. However, the lack of complete charging data is common in practice, which poses a challenge for the charging-based SOH estimators. This article proposes a multistage SOH estimation method with a broad scope of applications, including the unfavorable but practical scenarios of heavily partial charging. In particular, different sets of health indicators (HIs), covering both the morphological incremental capacity features and the voltage entropy information, are extracted from the partial constant-current charging data with different initial charging voltages to characterize the aging status. Following this endeavor, artificial neural network based HI fusion is proposed to estimate the SOH of LIB precisely in real time. The proposed method is evaluated with long-term aging experiments performed on different types of LIBs. Results validate several superior merits of the proposed method, including high estimation accuracy, high tolerance to partial charging, strong robustness to cell inconsistency, and wide generality to different battery types.
TL;DR: In this paper , the performance evaluation and reliability validation at the system-level applications seriously limits their further development and even future commercialization, and a beveled-mesa NiO/Ga was implemented in a 500-W power factor correction (PFC) system circuit.
Abstract: The technical progress of Ga 2 O 3 power diodes is now stuck at a critical point where a lack of performance evaluation and reliability validation at the system-level applications seriously limits their further development and even future commercialization. In this letter, by implementing beveled-mesa NiO/Ga 2 O 3 p–n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, high conversion efficiency of 98.5% with 100-min stable operating capability has been demonstrated. In particular, rugged reliability is validated after over 1 million times dynamic breakdown with a 1.2-kV peak overvoltage. Meanwhile, superior device performance is achieved, including a static breakdown voltage (BV) of 1.95 kV, a dynamic BV of 2.23 kV, a forward current of 20 A (2 kA/cm 2 current density), and a differential specific on -resistance of 1.9 mΩ·cm 2 . These results indicate that Ga 2 O 3 power HJDs are developing rapidly with their own advantages, presenting the enormous potential in high-efficiency, high-power, and high-reliability applications.
TL;DR: In this article , a comprehensive review, critical analysis, and categorization of the existing topologies of multilevel inverters with switched-capacitor (SC) units are presented.
Abstract: Multilevel inverters (MLIs) with switched-capacitor (SC) units have been a widely rehearsed research topic in power electronics since the last decade. Inductorless/transformerless operation with voltage-boosting feature and inherent capacitor self-voltage balancing performance with a reduced electromagnetic interference make the SC-MLI an attractive converter over the other available counterparts for various applications. There have been many developed SC-MLI structures recently put forward, where different basic switching techniques are used to generate multiple (discrete) output voltage levels. In general, the priority of the topological development is motivated by the number of output voltage levels, overall voltage gain, and full dc-link voltage utilization, while reducing the component counts and stress on devices for better efficiency and power density. To facilitate the direction of future research in SC-MLIs, this article presents a comprehensive review, critical analysis, and categorization of the existing topologies. Common fundamental units are generalized and summarized with their merits and demerits. Ultimately, major challenges and research directions are outlined leading to the future technology roadmap for more practical applications.
TL;DR: In this article, a high-density isolated auxiliary power supply (APS) using an LCCL-LC resonant topology with an operating frequency of 1 MHz is presented. But the proposed design procedure attains consistent soft-switching operation under a random number of output channels.
Abstract: The auxiliary power supply (APS) is one of the critical components inside medium-voltage (MV) power converters. Besides high insulation capability and small footprint, low common-mode (CM) coupling capacitance and multichannel output are the desired features of APS in the emerging silicon-carbide-based MV converters due to their fast switching speed. This article presents the design and optimization procedure of a high-density isolated APS using an LCCL-LC resonant topology with an operating frequency of 1 MHz. The proposed design procedure attains consistent soft-switching operation under a random number of output channels. The galvanic isolation is realized by a current-fed single-turn 1 MHz transformer that can achieve a breakdown voltage of over 20 kV while maintaining a small size. Design optimization on the insulation system of the current transformer is proposed to obtain both high partial-discharge inception voltage (PDIV) and low coupling capacitance. Finally, two versions of APSs are developed, using air and silicone as dielectric materials, which can reach PDIV of over 5 and 16 kV, respectively. The corresponding coupling capacitances are 1.86 pF and 3.6 pF. Both designs can provide a maximum power of 20 W on the receiving side, and 120 W on the sending side.
TL;DR: This article revisits the design of the current controller for grid-connected voltage-source converters (VSCs), considering the dynamic impacts of the phase-locked loop (PLL), weak grids, and of voltage feedforward (VFF) control.
Abstract: This article revisits the design of the current controller for grid-connected voltage-source converters (VSCs), considering the dynamic impacts of the phase-locked loop (PLL), weak grids, and of voltage feedforward (VFF) control. First, a single-input single-output transfer-function-based model is proposed to characterize the interactions of control loops. It is analytically found that the proportional gain of the current controller essentially aggravates the instability effect of PLL in weak grids, while the cutoff frequency of the low-pass filter used with the VFF loop has a nonmonotonic relationship with the PLL-induced instability. Then, based on these findings, a guideline for redesigning the current controller of PLL-synchronized VSCs is developed, which enables a codesign of the current controller and VFF controller. Finally, simulation and experimental results confirm the validity of theoretical analyses.
TL;DR: In this paper, a transformed unsaturated inductance characteristic-based method is proposed for the rotor position of the switched reluctance machine, which can serve as a low-effort way to provide the accurate rotor position for the industry application at medium and high-speed ranges.
Abstract: In this letter, a transformed unsaturated inductance characteristic-based method is proposed for the rotor position of the switched reluctance machine. Due to the magnetic saturation effect, the phase inductance characteristics have a narrow linear region, which increases the difficulty of their analytical expression. To reduce the complexity of the analytical expression, the unsaturated inductance characteristic is transformed from the phase inductance characteristics. Then, a linear model is presented to explicitly describe the relationship between the rotor position and unsaturated phase inductance. Experimental verification is carried out to verify the effectiveness and accuracy of the proposed method. The proposed method can serve as a low-effort way to provide the accurate rotor position for the industry application at medium and high-speed ranges.
TL;DR: In this article, a switch reduction scheme on reverse-blocking device bridges is proposed to reduce device count and the number of devices on the dc-link current path, which can be applied to the dc ports of dc-ac, ac-dc, or dc-dc hardswitching or soft-switching CSC-based SSTs.
Abstract: Solid-state dc transformer to integrate low-voltage dc (LVdc) microgrid, wind turbine (WT) generator, photovoltaic (PV), and energy storage (ES) into medium-voltage (MV) direct-current (MVdc) distribution grids is attractive. This article proposes current-source dc solid-state transformer (SST) for MVdc collection system in WT, PV, and ES farms or as an interface between the MVdc grid and the LVdc microgrid. Compared to conventional current-source converter (CSC) based SSTs, a switch reduction scheme on reverse-blocking device bridges is proposed to reduce device count and the number of devices on the dc-link current path. Importantly, the proposed switch reduction scheme is generic and can be applied to the dc ports of dc–ac, ac–dc, or dc–dc hard-switching or soft-switching CSC-based SSTs. Based on this scheme, the proposed current-source dc SSTs are derived, which have reduced electrolytic-capacitor-less dc-link. The proposed dc SSTs also achieve single-stage isolated dc–dc or dc–ac conversion, full-range zero-voltage switching (ZVS) for main switches, zero-current switching (ZCS) for resonant switches, and controlled $ dv/dt $ . The proposed dc SSTs, operating principles, predictive control method, the ZVS, and the controlled $ dv/dt $ under voltage buck-boost ranges are verified with MV simulations and an experimental prototype based on SiC mosfets , diodes, and a nanocrystalline transformer.
TL;DR: In this paper , a dual-active-synchronization (DAS) modulation is adopted with identical driving signals on both sides to solve unsmooth bidirectional power flow and current distortion in traditional CLLC-DCX with synchronization rectification modulation.
Abstract: The demand for isolated bidirectional dc transformer (DCX) is driven by the fast development of energy storage system, data center power supply and transportation electrification. Due to zero voltage switching (ZVS) and small rms current, the open-loop CLLC resonant converter operating at the resonant frequency is considered a promising candidate for DCX with a constant voltage transfer ratio. To solve unsmooth bidirectional power flow and current distortion in traditional CLLC-DCX with synchronization rectification (SR) modulation, a dual-active-synchronization (DAS) modulation is adopted with identical driving signals on both sides. Firstly, the switching transition of this modulation is fully analyzed with the consideration of large device output capacitances. After comparison of different transitions, a so-called Sync-ZVS transition is found more desirable with ZVS, no deadtime conduction loss, and load-independent voltage gain. In order to achieve this switching transition, an Axis and Center Symmetric (ACS) method is proposed. Based on this method, an overall design procedure of CLLC-DCX with DAS modulation is also proposed. Finally, Sync-ZVS transition and the proposed ACS method are both verified by three 18 kW 500 kHz prototypes with a 98.8% peak efficiency. This article is accompanied by one video demonstrating the load changing test.
TL;DR: A new duty-ratio regulation-based strategy to improve the torque performance for the direct torque control (DTC) of three-phase permanent magnet synchronous motors (PMSMs) using a virtual reference generator to mitigate the steady-state torque error.
Abstract: This article proposes a new duty-ratio regulation-based strategy to improve the torque performance for the direct torque control (DTC) of three-phase permanent magnet synchronous motors (PMSMs). The conventional DTC schemes utilize two hysteresis regulators that are hard to be tuned to satisfy proper torque performance for wide speed ranges because of the contrary change in the positive and the negative torque deviations of the converter's voltage vectors with the rotational speed variations. In contrast, the proposed method uses a duty-ratio regulator that considers the operating speed impact on the torque deviation of the active voltage vectors and avoids triggering those of them that produce high torque deviations, therefore reducing the torque ripple of the DTC system. Moreover, it proposes a virtual reference generator to mitigate the steady-state torque error. The proposed method provides enhanced torque control performance, meanwhile maintaining the main advantages of the conventional DTC techniques, including simple structure, fast transient response, and good robustness. The feasibility and effectiveness of the proposed strategy are verified through a detailed comparative assessment with the conventional DTC scheme and two existing duty regulation-based methods using experimental results obtained from a 0.75-kW PMSM drive system.
TL;DR: In this article , an online multifault diagnosis strategy based on the fusion of model-based and entropy methods is proposed to detect and isolate multiple types of faults, including current, voltage, and temperature sensor faults, short-circuit faults, and connection faults.
Abstract: Various faults in the lithium-ion battery system pose a threat to the performance and safety of the battery. However, early faults are difficult to detect, and false alarms occasionally occur due to similar features of the faults. In this article, an online multifault diagnosis strategy based on the fusion of model-based and entropy methods is proposed to detect and isolate multiple types of faults, including current, voltage, and temperature sensor faults, short-circuit faults, and connection faults. An interleaved voltage measurement topology is adopted to distinguish voltage sensor faults from battery short-circuit or connection faults. Based on the established comprehensive battery model, structural analysis is performed to develop diagnostic tests that are sensitive to different faults. Residual generation based on the extended Kalman filter and residual evaluation based on the statistical inference are conducted to detect and isolate sensor faults. Sample entropy is used to further distinguish between the short-circuit faults and connection faults. The effectiveness of the proposed diagnostic method is verified by multiple fault tests with different fault types and sizes. The results also show that the proposed method has good robustness to noise and inconsistencies in the state of charge and temperature.
TL;DR: A comparison of the proposed topology with other contemporary SCMLIs shows that it is highly competent in terms of CF, PIV and TSV requirements, waveform resolution, and capability to achieve voltage balancing of capacitors at low values of modulation index.
Abstract: The merit of switched-capacitors-based multilevel inverters (SCMLIs) is generally quantified in terms of a “cost function” (CF) that incorporates parameters such as voltage gain, component count, total standing voltage (TSV), and number of levels. In this article, a 13-level inverter is proposed with the aim of achieving a low value of CF. The proposed single-stage SCMLI uses one input source and three capacitors to attain a voltage gain of 3. It requires 13 power switches, of which the peak inverse voltage (PIV) of nine switches is restricted to the source voltage. The remaining four switches have PIV equal to twice the source voltage and they operate at low frequency. Thus, for all switches, the PIV is less than the amplitude of the output voltage. Moreover, the capacitors are self-balanced at all regions of modulation index values. The proposed inverter is validated through simulation and experimental results. A comparison of the proposed topology with other contemporary SCMLIs shows that it is highly competent in terms of CF, PIV and TSV requirements, waveform resolution, and capability to achieve voltage balancing of capacitors at low values of modulation index.
TL;DR: In this paper, a low complexity finite-control-set model predictive control (FCS-MPC) based on the discrete space vector modulation (DSVM) is proposed for T-type three-phase three-level (3P-3L) converters.
Abstract: In this article, a low complexity finite-control-set model predictive control (FCS-MPC) based on the discrete space vector modulation (DSVM) is proposed for T-type three-phase three-level (3P-3L) converters. Different from the conventional FCS-MPC, 48 virtual voltage vectors (VVs) of the converter are constructed by real VVs based on the DSVM. Thus, the performance of 3P-3L converters is significantly improved and the peak amplitude of high-order harmonics concentrates at the sampling frequency. Furthermore, two-stage FCS-MPC based on virtual VVs is proposed to reduce the computation burden. Its first stage selects one of six virtual VVs that minimizes the current tracking error. Then, these candidate VVs located in the same sector as the optimal virtual VV selected in the first stage are evaluated in the second-stage optimization. Thus, the computational efficiency has been greatly improved. To verify the validity of the proposed control method and show its superiority over the conventional FCS-MPC, experimental results are presented.
TL;DR: In this article, two virtual vector (VV) based SVPWM-DTC (DTC1 and DTC2) methods are proposed to provide better speed and torque control.
Abstract: In multiphase induction motor drives, lowering the common-mode voltage (CMV) reduces motor insulation degradation and the existence of destructive bearing current. For this investigation, a five-phase two-level voltage source inverter (FPTL-VSI) fed five-phase induction motor (FPIM) drive is used. FPTL-VSI produces increased CMV, which cannot be totally removed. Moreover, CMV can be reduced by 80% in contrast to its peak-to-peak value with suitable selection of small and large voltage vectors in a space vector pulsewidth modulation (SVPWM) scheme. Direct torque control (DTC) combined with the SVPWM scheme can accomplish such reduced CMV performance at constant switching frequency. To provide better speed and torque control, two virtual vector (VV) based SVPWM-DTC (DTC1 and DTC2) methods are proposed in this study. Over a wide range of modulation index, the influence of each voltage VV on motor drive speed and torque response is investigated. The proposed DTC1 and DTC2 schemes are validated under steady-state and dynamic conditions over a wide range of speed fluctuations using a high-power laboratory prototype of $3.8\,\text{{k}W}$ FPIM drive. The efficacy of the proposed DTC1 and DTC2 is compared to the current literature by evaluating the effectiveness of CMV and the switching frequency.
TL;DR: In this article , a comprehensive review of power architecture, functional blocks including electrical machines and energy storage, as well as power converters in dc shipboard power systems is presented, where the authors make a comprehensive comparison of power architectures and functional blocks.
Abstract: Integrated power systems are popular in the shipbuilding industry. DC shipboard microgrids (dc-SMGs) have many advantages compared with ac ones in terms of system efficiency, operation flexibility, component size, and fault protection performance. Being in the exploring stage, dc-SMGs have several potential configurations with different system architectures and voltage levels. In a dc-SMG, functional blocks integrated include power generation modules (PGMs), propulsion system, high power loads, and pulsed loads specifically in naval ships. In modern ships, the PGMs include not only generators and fuel cells but also energy storage systems (ESSs), which cooperate with generators to improve the overall efficiency and reliability. High power electric converters are vital interfaces between the functional blocks and the dc distribution system. Rectifiers for generators take the tasks of dc bus voltage regulation and power sharing. Inverters for propulsion motors are responsible for the motor drive in different operating conditions. Bidirectional dc/dc converters for ESSs are used to provide supply-demand balance and voltage fluctuation mitigation. This article makes a comprehensive review of power architecture, functional blocks including electrical machines and energy storage, as well as power converters in dc shipboard power systems.
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TL;DR: In this paper , an improved machine-learning-based fault diagnosis method with adaptive secondary sampling filtering is proposed for the multiphase drive systems, and the results of the proposed method on both five-phase and six-phase motor drive platforms validate its satisfying generalization capability as well as high accuracy and robustness.
Abstract: Dueto various kinds of stator phase arrangements, existing fault diagnosis (FD) methods cannot be applied to different types of multiphase machines. Spurred by the era of big data and artificial intelligence, an improved machine-learning-based FD method with adaptive secondary sampling filtering is proposed for the multiphase drive systems. Experimental results of the proposed method on both five-phase and six-phase motor drive platforms validate its satisfying generalization capability as well as high accuracy and strong robustness.
TL;DR: In this paper, a miniaturized split-phase half-turn transformer is demonstrated, which leverages the well-established parallelization benefit of employing multiple phases, as in a matrix transformer, with the dramatic reduction in copper loss associated with the relatively new Variable Inverter/Rectifier Transformer (VIRT) architecture.
Abstract: High step-down, high output current converters are required in many common and emerging applications, including data center server power supplies, point-of-load converters, and electric vehicle charging. Miniaturization is desirable but challenging owing to the high step-down transformer ubiquitously used in these converters. In this work, a miniaturized split-phase half-turn transformer is demonstrated, which leverages the well-established parallelization benefit of employing multiple phases, as in a matrix transformer, with the dramatic reduction in copper loss associated with the relatively new Variable Inverter/Rectifier Transformer (VIRT) architecture. While these techniques have been described in earlier studies, their combination has not been well explored. A detailed design procedure is described and is used to develop a 97.7% peak efficiency and 97.1% full-load efficiency prototype having a transformer that is 12%–36% smaller than best-in-class designs in the literature at the same power level while also being more efficient. This work showcases the miniaturization benefit of employing multiphase, fractional-turn transformers in high step-down, high output current applications and provides comprehensive guidance to designers interested in applying and extending these techniques.
TL;DR: In this paper , an improved machine-learning-based fault diagnosis method with adaptive secondary sampling filtering is proposed for the multiphase drive systems, and the experimental results of the proposed method on both five-phase and six-phase motor drive platforms validate its satisfying generalization capability as well as high accuracy and strong robustness.
Abstract: Dueto various kinds of stator phase arrangements, existing fault diagnosis (FD) methods cannot be applied to different types of multiphase machines. Spurred by the era of big data and artificial intelligence, an improved machine-learning-based FD method with adaptive secondary sampling filtering is proposed for the multiphase drive systems. Experimental results of the proposed method on both five-phase and six-phase motor drive platforms validate its satisfying generalization capability as well as high accuracy and strong robustness.
TL;DR: In this paper , a misalignment-tolerant dual-transmitter EV wireless charging system with a reconfigurable topology is proposed, where the two transmitting coils are connected in series to feed the load.
Abstract: Wirelesscharging for electric vehicles (EVs) enjoys many benefits, such as convenience, safety, and automation. One of the major issues concerning EV wireless charging is misalignment tolerance along the door-to-door direction of the EV. This letter proposes a misalignment-tolerant dual-transmitter EV wireless charging system with a reconfigurable topology. At central positions, the system can be reconfigured to the S-S (series-series) topology where the two transmitting coils are connected in series to feed the load. At boundary positions, the two transmitting coils form the LCCC-S (inductor-capacitor-capacitor-capacitor-series) topology to enhance power transfer capability and tolerate weak couplings. In this way, not only the output power can be smoothed with door-to-door misalignment, but also wireless charging is guaranteed at weak couplings. Experimental results reveal that within the cover area of the transmitting coils, high-efficiency stable output can be achieved.