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Expressing switched-inductor converter losses simply as a function of design variables is key for designers. Power losses in switched-inductor power supplies are varied in nature, and optimization schemes in the literature fail to account for all of them. Available core loss models are mostly empirical or rely on measurements or variables beyond the reach of power supply designers. Specifically, a simple core loss model is missing. This work offers complete design optimization of switched-inductor power supplies with a quadratic model of core loss that relies solely on design variables known to the designers—inductance and switching frequency (or inductor peak current). This model alleviates the burden of performing complex measurements to characterize the inductor—measurements that, moreover, require geometric data about the core, such as its size, which are often not disclosed by the manufacturer. Predicted minimum losses without approximation are within 3.2% of measured minimum losses, and predicted minimum losses with approximation are within 2.2% of measured minimum losses. [ABSTRACT FROM AUTHOR]

Since voltage stress of semiconductors is equal to the input voltage in the conventional buck converter, the voltage stress of semiconductors is high in high input voltage application. In addition, ripple voltage across the output filter varies with the input voltage, so volume and weight of the output filter increases. Therefore, the buck converter integrated with a CDD circuit is proposed to address the aforementioned problems. Voltage stress of semiconductors is constant and is equal to the output voltage. Thus, voltage stress of semiconductors is reduced in the high input voltage application and efficiency of the system can be improved because of low voltage stress of semiconductors. In addition, ripple voltage across the output filter is also constant and is equal to the output voltage, so volume and weight of the output filter can be reduced when input voltage varies. Operating principle of the proposed converter is elaborated. Design guideline and examples are given. Loss of the converter is analyzed. Comparison among different buck-type converters is presented. Lastly, experimental results confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]

Building energy management usually involves a number of objectives, such as investment costs, thermal comfort, system resilience, battery life, and many others. However, most existing studies merely consider optimizing less than three objectives since it becomes increasingly difficult as the number of objectives increases. In addition, the optimization of building energy management relies heavily on time-consuming energy component simulators, posing great challenges for conventional evolutionary algorithms that typically require a large number of real function evaluations. To address the above-mentioned issues, this paper formulates a building energy management scenario as a 10-objective optimization problem, aiming to find optimal configurations of power supply components. To solve this expensive many-objective optimization problem, six state-of-the-art multi-objective evolutionary algorithms, five of which are assisted by surrogate models, are compared. The experimental results show that the adaptive reference vector assisted algorithm is proven to be the most competitive one among the six compared algorithms; the five evolutionary algorithms with surrogate assistance always outperform their counterpart without the surrogate, although the kriging-assisted reference vector assisted evolutionary algorithm only performs slightly better than the algorithm without surrogate assistance in dealing with the 10-objective building energy management problem. By analyzing the non-dominated solutions obtained by the six algorithms, an optimal configuration of power supply components can be obtained within an affordable period of time, providing decision makers with new insights into the building energy management problem. [ABSTRACT FROM AUTHOR]

To cope with the megatrends electrification, automated driving, and connectivity, new functionalities and electric and/or electronic systems must be developed, which require a safe power supply. This leads to increased functional safety requirements for the power supply system, particularly regarding availability. Fault tolerance measures can be implemented to comply with a safety goal (SG) specifying a safety-related availability requirement. To verify an architecture concerning the residual risk of an SG violation, several quantitative target values are provided in ISO 26262. This technical elaboration presents a systematic and holistic approach how to gain benefit in the quantitative evaluation from cyclic safety mechanisms (SMs)– in a fault tolerant item– which have a fault handling time interval (FHTI) longer than the fault tolerant time interval. Modelling cyclic SMs only based on conventional AND-gates is not sufficient. Instead, the fault sequence is differentiated to enable ISO 26262-compliance. Within this paper, an innovative approach including its mathematical background is presented how cyclic SMs can be modelled in a fault tree analysis– with focus on multiple-point faults. The results are verified by a Monte-Carlo-Simulation. Besides the scalability of the approach regarding the number of considered cyclic SMs, the relevant FHTI of each cyclic SM can be considered in a traceable and comprehensible manner.

For the open winding permanent magnet synchronous motor (OW-PMSM) with leg open-circuit faults, a novel zero-sequence current (ZSC) suppression method with asymmetric zero-sequence voltage (ZSV) injection is proposed in this article. To realize the fault-tolerant control (FTC) in leg open-circuit fault conditions, the leg-sharing method is developed, where the output terminal of the faulty leg is connected to that of the remaining equivalent leg. However, the ZSC increases in the FTC mode, which causes severe torque ripple and system performance degradation. If the traditional ZSC suppression method is still adopted, the suppression performance is decreased. Besides, an undesired voltage vector is introduced, resulting in current distortion. To solve these problems, a novel ZSC suppression strategy is put forward. By asymmetrically adjusting the voltage output of the remaining legs, the ZSC of OW-PMSM in FTC mode can be effectively suppressed. Moreover, the proposed strategy is suitable for both the single-leg and double-leg FTC modes, where the ZSC suppression performance is almost the same as that of the traditional method in normal operation mode. Furthermore, experiments are performed on an OW-PMSM to verify the effectiveness of the proposed ZSC suppression scheme. [ABSTRACT FROM AUTHOR]

Modular multilevel converter (MMC)-based solid-state transformers (M-SSTs) show promise in hybrid ac/dc distribution grids where there is need for a medium-voltage dc (MVdc) interface. It can be used to interconnect several distribution networks with different voltage forms and levels and enable flexible power flow among them. In an M-SST, the MVdc short-circuit fault is a critical issue due to the rapidity of the fault current, which can cause device damage and power failure of the low-voltage (LV) grids. Aiming at addressing this issue, this article proposes a fault-mode control strategy applied to a hybrid M-SST topology for uninterrupted power supply of its LV ports. The topology consists of a hybrid MMC with both half- and full-bridge submodules and isolated bidirectional dc–dc converters. Through the proposed control, the fault current is eliminated when an MVdc short-circuit fault occurs. The hybrid M-SST can keep uninterrupted power interaction between the MVac port and the LVdc port during the fault, thereby improving power supply reliability. Moreover, an improved capacitor voltage balance control and an optimized modulation scheme are developed and included in the uninterrupted operation scheme to maintain the harmonic performance of the ac port. The feasibility and effectiveness of the proposed topology and control are verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

As hardware security becomes a crucial challenge for modern electronic devices to protect information privacy, this article presents an encrypted on-chip power supply to combat power and electromagnetic (EM) side-channel attacks (SCAs) for crypto cores. By splitting power and security into separate paths, random parallel power injection and charge recycling are realized to encrypt supply power activities for high SCA immunity while largely minimizing power and performance overheads. Despite of crypto core power variations, the proposed power supply can maintain uncorrelated input profile by adaptively modulating parallel noisy power injection. Moreover, its EM leakage is highly attenuated by spreading the spectrum energy to a wide frequency range and increasing noise floor. To achieve such, a recycled masking power stage with an encryption interface is designed to randomly inject power noise and recycle system charge with random on-time modulation while still retaining nominal power delivery. A silicon IC prototype of this design is fabricated using a 65 nm CMOS process with an active die area of 0.19 mm2. Measured input power profiles are fully encrypted to improve power SCA immunity. Operating at a nominal switching frequency of 10 MHz, random parallel power encryption reduces peak EM interference noise from 64.57 dBμV to 43.12 dBμV to meet EN55032 Class B standards and verify EM spectrum profile encryption. In response to a step-up load change from zero to full load current of 200 mA, the power supply achieves 1% settling time of 0.78 μs, with measured voltage droop of 54 mV with no other performance overhead. It achieves a peak efficiency of 90.5%, only suffering the maximum power overhead of 4.9%. [ABSTRACT FROM AUTHOR]

The medium-voltage dc (MVDC) system are intensely investigated by both industry and academy. However, how to realize a lower power circuit directly fed by MVDC is an important but easily neglected problem, which seriously affects the reliability of the dc system. The current high step-down circuits are mostly suitable for high-power applications, while the circuits for low-power applications are designed case by case. To address the obstacle, a generalized buck-boost type high step-down converter (BHSC) structure is proposed in this article. The submodules of BHSC are derived from basic dc–dc converter. As a result, the features of high modularity, simple structure, and low cost can be obtained, and each submodule operates independently without communication and synchronization to achieve voltage balance. Furthermore, a submodule strategy with Bang-Bang control, instead of hardware modification, is proposed to overcome the limitation of BHSC generality in medium-voltage (MV) and high-voltage (HV) applications, due to the operating current difference in different submodules of the cascaded structure. Therefore, BHSC can be easily extended to MV or HV by increasing the number of submodules. Finally, an experimental evaluation of a 1 kV/80 W prototype converter is presented, which can be applied as auxiliary power supply for high-power converter. [ABSTRACT FROM AUTHOR]

Series-parallel-form switch-linear hybrid envelope tracking power supply is composed of a voltage-controlled linear amplifier (VLA), a voltage-controlled switched-mode converter (VSC) and a current-controlled switched-mode converter. When the VLA adopts a class AB linear amplifier, an additional VSC can be added to be in series with the bottom transistor of the VLA to reduce its voltage drop. In order to reduce the system complexity, this article proposes to employ multiple bidirectional converters to implement the voltage-level provider, for being shared by the two VSCs, which are implemented with multilevel converters. Then, the loss model of the system is established, and based on which, an optimized design of the voltage-level number and voltage-level values of the multilevel converters is presented for improving the overall system efficiency. Finally, a prototype is fabricated aiming for tracking the envelope signal with 10-MHz bandwidth, 9.6–26.4-V output voltage, and 20-W average output power. The measured system efficiency is 78.79%, an improvement by 2.58% with the additional VSC. [ABSTRACT FROM AUTHOR]

Multilevel converters with floating capacitors generally require precharging to build up the voltage on floating capacitors and dc-link before the normal operation. In particular, precharge is challenging for converters with overvoltage concerns under initial zero capacitor voltages. As a promising topology, seven-level hybrid clamped (7L-HC) converters also require precharge of capacitors and shall avoid high voltage stress during the precharge. Considering the high cost of deploying extra dedicated precharge circuits in a medium voltage system, the precharging method without relying on dedicated power supplies is favored. In this article, specific switching states and their corresponding selection schemes are designed to precharge floating capacitors of back-to-back 7L-HC converters. In this process, the inrush current and voltage stress can always be limited in the safe range. This method only needs series and shunt resistors typically already exist in practical converter circuits, resulting in low cost and ease of implementation. The design method of the resistances is also provided. Both simulation and experimental results validate the feasibility of this method. [ABSTRACT FROM AUTHOR]

High-voltage pulse power supplies are key power input devices for the study and application of discharge plasma. A high-voltage pulse current power supply (HV-PCPS) with an energy storage pulse transformer based on flyback topology can output microsecond pulsewidths with high-power, ultrahigh voltage, and high reliability, which are suitable for most dielectric barrier discharge (DBD) plasma applications. However, during the process of DBD driven by an HV-PCPS based on an energy storage pulse transformer, the output pulse voltage waveform quality is poor, making it not suitable for stable discharge long-term operation. This article aims to solve the aforementioned problem and proposes a novel resistor–diode–diode (RDD) shaping method. Not only can this novel method solve the problem of poor quality of the output pulse power from the HV-PCPS, guaranteeing stable discharge for various DBD electrodes, it can also limit the maximum output voltage amplitude. This prevents overvoltage breakdown when the output terminal is in an open state or a light load state because the HV-PCPS is acting as a current source. This article also analyzes the effectiveness of an RDD branch when solving the problem in theory, and gives a detailed parameter design method. Finally, a 30-kV HV-PCPS prototype is built to verify the effectiveness of the proposed RDD pulse shaping method. The average pulse power output of the whole prototype is greatly improved, and it can achieve an average pulse power output of 1 kW. Furthermore, the electrode loads of different DBD reactors can be driven by this technology. [ABSTRACT FROM AUTHOR]

Mission profile emulation (MPE) for submodules (SMs) in the modular multilevel converter (MMC) is a crucial step before a full-scale system is put into field operation. Existing methods suffer from limitations of the testing accuracy due to the staircase-like arm voltages that result in distorted loading current and require large filter inductance. This is especially the case when a limited number of SMs are under test. In this article, an efficient MPE method is proposed to emulate the loading behaviors of multiple SMs in MMC. The testing circuit allows two arms of MMC with flexible SM number, operating in inverting and rectifying mode under nearest level modulation, to be tested simultaneously with reduced dc supply voltage. A common H-bridge circuit is introduced in the testing circuit, with each arm of the H-bridge circuit functioning as the voltage compensator by using feedforward control. In this way, the current distortion can be significantly suppressed, and testing accuracy can be guaranteed in a cost-efficient manner even though no large inductor is included in the testing circuit. The proposed method allows SMs under test to be loaded as in the actual back-to-back MMC system. Simulations and experimental measurements are given to validate the proposed method. [ABSTRACT FROM AUTHOR]

This article describes a 3-kW simmer and 30-kV dc trigger power supply system for driving xenon flash lamps in large-area processes. Simmer power supply is designed to output maximum of 3 kV for maintaining the lighting state of the lamp after having triggered and to supply low ripple current continuously for maintaining the ignited state. It is designed based on an LCC resonant converter and design and implementation of the high-voltage transformer and output rectifier are presented. For igniting xenon lamps, dc trigger is designed to output a maximum of 30 kV auxiliary trigger voltage. The system that both power supplies is operated by one main inverter is presented. Through the resistive-load test, it is verified that the simmer outputs 600 V, 5 A under rated-load condition and 120 V, 1 A under light-load conditions. It is also verified that the simmer outputs 3 kV and the dc trigger outputs 30 kV under the no-load condition.Finally, the simmer and dc trigger power supply system is applied to lighting various xenon lamps from single lamp (306 mm, 8Φ) to three series lamps (400 mm, 26Φ). Required output voltages for stable driving various types of xenon lamps in the lighting mode are presented. [ABSTRACT FROM AUTHOR]

The series-form switch-linear hybrid envelope tracking (ET) power supply is constituted by a multilevel converter and a linear amplifier connected in series, featuring high efficiency and wide tracking bandwidth. With the development of wireless communication, the envelope bandwidth of the radio-frequency signal reaches tens of megahertz and even hundreds of megahertz, leading to a high switching loss in the multilevel converter and thus degraded overall efficiency of the ET power supply. To reduce the switching loss and ensure high tracking bandwidth, this article proposes to let the multilevel converter track the reduced bandwidth envelope signal and the linear amplifier track the original one. Then, a step-wave edge adjustment method is proposed to adjust or eliminate the rising and falling edges of the step-wave voltage for further reducing the equivalent switching frequency of the multilevel converter and the voltage across the power device of the linear amplifier. As a result, the switching loss in the multilevel converter and the power loss in the linear amplifier could be reduced, leading to a notably higher overall efficiency. A prototype with 40 MHz tracking bandwidth, 7–27 V output voltage, and 15 W average output power is fabricated and tested in the lab, and the experimental results are provided to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In the low-speed operating range of sensorless interior permanent magnet synchronous motor (IPMSM), this article proposed an ultrahigh frequency (UHF) sinusoidal voltage injection method supplied by the control power supply, and the corresponding signal injection and detection system topology are designed. The proposed method replaces the traditional high-frequency injection method to continuously detect the rotor position by injecting UHF sinusoidal detection voltage into the three-phase motor windings during the main power supply (MPS) down, thereby avoiding the loss of rotor polarity information. When the MPS is restored, there is no need to wait for the convergence process of the position observer and the rotor polarity determination process. The sensorless IPMSM can immediately resume normal operation at low speed. For applications with low load inertia, the proposed method improves the rapidness of rotating restart, realizes zero-wait operation after MPS is restored, and reduces the speed drop during the power down. For electric vehicle (EV) applications, the proposed method meets the requirements of EVs event data recorder to continuously record the motor speed when the MPS is off. The experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

In automated storage and retrieval systems (ASRS), adopting wireless power transfer (WPT) technology is an available way to avoid the drawbacks of the contact power supply system for multiple stackers. When stackers are dropping goods, it is meaningful to recycle the power generated by the motors and feedback to the other stackers or the ground power supply for improving the overall efficiency of ASRS. This article proposes a bidirectional WPT (BD-WPT) system for multiple receivers. Based on the values of transmission power and the power flow directions of receivers, a general model of the BD-WPT system is established with identifying the system operation modes and their boundaries. To achieve flexible switching among different operation modes and adapt the required transmission power with maximum efficiency point tracking (MEPT), a control strategy of the BD-WPT system is proposed. In the 2-kW experimental prototype built, the power demands can be met in real time, and the power fed back by the stackers can be supplied to other loads or recycled by the ground power supply with good dynamic performance. Compared with the system without MEPT, the efficiency of the proposed system is improved by 26.7% at most, and the maximum efficiency achieves 96.4%. [ABSTRACT FROM AUTHOR]

Near-infrared spectroscopy (NIRS) technology is a noninvasive technology that can detect the hemoglobin concentration in the shallow tissue of humans in the form of an optical signal and determine the muscle’s activation state based on the change of hemoglobin concentration. It has a broad application prospect in the biomedical and physiological signal analysis. There are specific requirements for the structure of NIRS sensors for different application scenarios. The muscle synergy theory explains that body movements are often accompanied by the cooperation of many different muscles. Therefore, a multichannel NIRS system is necessary for motion recognition. This article presents a distributed multichannel NIRS system. The wireless communication avoids the interference of signal lines, and the equipped upper computer system can display NIRS signals in real time. Our NIRS sensors have three different wavelengths of near-infrared light (750, 800, and 850 nm) and two photodiodes, which can effectively improve the sampling accuracy of the signal. Experimental verification and evaluation prove that our system’s performance and reliability are better than those of other NIRS systems. Finally, cuff occlusion and hand motion experiments demonstrated that blood flow and oxygen consumption are the two main factors that cause hemoglobin concentration changes. We offer a new scheme for NIRS signal analysis that uses the common mode and difference mode of Hb and HbO2, and the results demonstrate its superior performance. In future work, we will discuss the application and effect of the NIRS system in rehabilitation training. [ABSTRACT FROM AUTHOR]

The automotive industry is currently driven by the megatrends electrification, automated driving and connectivity. To cope with these trends, new functionalities and electrical and/or electronic (E/E) systems need to be developed and deployed. Independent of the implementation of E/E systems, their power input shall be ensured by the power supply system as a shared resource – leading to increased functional safety requirements for power supply systems. If the loss of an item’s functionality can lead to a hazardous event, a safety goal (SG) specifying a safety-related availability (SaRA) requirement is derived. Thereby, switching to passive mode typically cannot be considered a safe state. To address an SG specifying a SaRA requirement, fault avoidance, fault forecasting and/or fault tolerance measures can be applied. In the case of fault tolerance measures implemented by redundancy, which leads to fail-active behavior, the performance of the backup system during nominal operation and after the first fault can be further refined. In this study, SaRA in the context of ISO 26262 is evaluated in detail and mapped to an example of the power supply domain.

The automotive industry is currently driven by the megatrends electrification, automated driving, and connectivity. To cope with these trends, new functionalities and electric and/or electronic systems must be developed, which require a safe power supply by the power supply system. This leads to increased functional safety requirements for the power supply system, particularly regarding availability. Fault tolerance measures can be implemented to address a safety goal specifying a safety-related availability requirement. In this case, emergency operation (EO) may be necessary to reach a defined safe state. The definitions and examples provided in ISO 26262 focus on cold redundancy, whereby the backup system is not engaged during nominal operation. The objective of this paper is to evaluate EO in the context of ISO 26262 in detail and map the results to an exemplary power supply system architecture implementing cold redundancy. In general, the EO is considered to be free from unreasonable risk even though the actual automotive safety integrity level (ASIL) capability of the item is lower than the initially specified ASIL rating for the hazard due to its timing restrictions. To determine the maximum permissible duration of EO, not just random hardware faults shall be considered; additionally, systematic effects shall be considered. Furthermore, an EO may be entered due to transient faults potentially causing temporary EOs – introducing the necessity of an EO recording, e.g. by accumulating the time of all temporary EOs.

To cope with the megatrends electrification, automated driving, and connectivity, new functionalities and E/E systems must be developed, which require a safe power supply. This leads to increased functional safety requirements for the power supply system, particularly regarding availability. Fault tolerance measures can be implemented to comply with an SG specifying a SaRA requirement. In this case, EO may be necessary to reach a defined safe state. However, there is some ambiguity in ISO 26262 regarding the necessary integrity with which the EO shall be implemented – this becomes in particular obvious in the case of warm redundancy. According to ISO 26262, the EO is entered once the failure of an element is controlled by an explicit fault handling, i.e., prevented from violating an SG, and the remaining ASIL capability of the item after the failure is lower than the required ASIL capability for the allowed VOS. However, in the context of warm redundancy, the EO can be automatically entered in the case of an element failure without an explicit fault handling. The objective of this paper is to transfer the concept of EO, as defined in ISO 26262, to warm redundancy use cases because warm-redundant power supply systems have a high level of market penetration. Besides a detailed evaluation of time dependencies, new guidelines concerning the required systematic integrity for SMs implementing EO are provided.

Although smart home has received wide attention in recent years, numerous scholars focus more on energy optimization strategy than energy dispatch hardware device (named energy router). Meanwhile, this energy router should have several features, i.e., high renewable energy utilization, energy multi-port and low volume. Thus, this paper designs a nine-port energy router regarding smart home and proposes a multimode hierarchical management strategy for this energy router. First, for the multi-port demand of wind, solar, storage and utilization, this paper presents a nine-port energy router to improve the renewable energy consumption and power supply flexibility. In addition, to reduce the volume of the energy router, a non-isolated AC/DC hybrid topology is constructed through embedding the integrated power electronic converters, which achieves the miniaturization of the energy router. In order to improve the renewable energy utilization rate, the decentralized module control is proposed for the components of energy router to provide the voltage and frequency support for system, and realizes the power sharing of distributed generations (DGs). Furthermore, the power exchange control with three-mode switching is proposed to guarantee the global energy flow balance under complex conditions. Eventually, the feasibility of the energy router is verified by the simulation and experiments. [ABSTRACT FROM AUTHOR]

The reason for the change of trench sidewall profile under low pressure of SF6/O2 containing plasma was explored by studying the trench morphology under different etching conditions. The result shows that the Si undercut decreases with the decreasing of pressure and the uniformity will become better. However, the sidewall of the trench presents a negatively tapered under low pressure. The reasons for different profile of trench are explored by the thickness of sidewall protective layer for the first time. The TEM results show that the trench sidewall forms a protective film with a thickness of about 100Å. The thickness of the oxide layer decreases from top to bottom. And the EDX results show that the main elements of the protective film are Si and O. Due to the decrease of oxide thickness, the width of trench bottom will become larger and larger, resulting in negatively tapered morphology. It is worth noting that the profile of trench changes to positively tapered again under the condition of low ratio of SF6/O2. Based on this, an optimized trench etching process is proposed and the etch rate is $1.15{\mu }\text{m}$ /min and the selectivity to the oxide mask is 14. [ABSTRACT FROM AUTHOR]

The integration of distributed photovoltaic and new energy vehicles could further aggravate the over-voltage, over-load, and three-phase voltage unbalance in distribution networks. Multistation integrated system (MSIS) can resolve the aforementioned power quality issues. In this article, a new topology for a MSIS is proposed, which uses soft open point as the key equipment of the system and adopts the hierarchical power supply mode for a data center, electric vehicle charging pile, and other function stations. Based on the topology of the MSIS and smooth switching of the converter control mode, a coordinated control strategy is proposed to control the working mode of each function station and further optimize the system operation conditions. The small signal model of the MSIS is derived, which can provide theoretical support for the stable operation of the system. The simulation results of two different application scenarios verify that the proposed topology of the MSIS and coordinated control strategy effectively improve the voltage level of the distribution network, enhance the reliability of sensitive load power supply, and ensure safe and reliable operation of the MSIS. Finally, the fusion and integration functions of the MSIS are tested and verified. The on-site demonstration indicated a mutual win–win situation for the power supply company, energy supplier, equipment provider and users. [ABSTRACT FROM AUTHOR]

An uninterruptible power supply (UPS) can reduce power failure loss by responding to power demand during distribution network failures. For reliability-sensitive power consumers, deploying UPSs is a solution for improving power supply reliability. Nevertheless, because of UPS devices’ energy limits and potential failure probability, power consumers with UPSs cannot guarantee 100% adequacy. In future power systems with frequent reconfiguration and massive storage facilities, the power supply adequacy of a consumer with respect to the network configuration and the storage capacity will need to be frequently evaluated. Furthermore, the analytical formulation of a consumer with a UPS should be investigated since the simulation-based method might witness low efficiency and poor convergency. Therefore, this paper proposes a novel analytical availability index calculation framework for adequacy evaluation. The framework models the uncertainties of distribution networks and UPS devices as stochastic processes. Then, the availability index calculation formula is acquired based on the stochastic modeling. Compared with existing methods, this paper incorporates UPS devices’ capacity and characteristics. Moreover, the distribution network configuration and protection device placement are considered. Case studies on an illustrative distribution network, the modified RBTS system, and a real distribution system in China validate the proposed method. [ABSTRACT FROM AUTHOR]

The postdisaster restoration capabilities for critical loads in distribution networks need to be enhanced. In recent years, electric buses (EBs) have been widely used with the carbon-neutral target, which can be dispatched and discharged for load restoration considering their mobility and the V2G technology. However, the restoration capabilities of EBs are limited by the transportation system while the ac distribution network can hardly achieve power transfer between lines due to the radial constraint. In this article, a coordinated restoration method of hybrid ac–dc distribution network with EBs is proposed, which has flexible power transfer capability. The control modes of voltage source converters (VSCs) during the postdisaster period as well as the EB restoration capability considering transportation system constraints are analyzed in detail. Then, a bilevel programming model is developed to optimize the network reconfiguration, VSC outputs, and the proposed EBs dispatching scheme simultaneously, in order to achieve a better power transfer capability for load restoration considering their coordination. Simulation studies are performed to verify the proposed method. [ABSTRACT FROM AUTHOR]

Extreme circumstances in which a local distribution system is electrically isolated from the main power supply may not always be avoidable. Efforts must be made to keep the lights on for such an isolated distribution system (IDS) until reconnection to the main power source. In this paper, we propose a strategy to enhance IDS survivability by utilizing the coordination of two flexible approaches, namely, separable mobile energy storage systems (SMESSs), which construct non-wires links for energy transmission between the IDS and the external live power sources, and demand response (DR), which adjusts the internal electrical demand of the IDS to provide effective operating stress alleviation. Considering the uncertainty of renewable energy generation (REG) and loads, a two-stage robust optimization (RO) model involving the joint scheduling of these two approaches is constructed. The objective is to minimize the fuel consumption and the decreased and unserved demand under the worst-case scenario to endow the IDS with extended survivability. Finally, test is conducted and the results demonstrate the effectiveness of the proposed method in enhancing the survivability of IDS. [ABSTRACT FROM AUTHOR]

A major upgrade will be conducted in the Large Hardon Collider (LHC) at CERN. This high-luminosity (HL) version of the LHC will increase the nominal luminosity by a factor of five. One of the key technologies of the HL-LHC is the new superconducting inner triplet (IT) magnets, responsible of producing high magnetic fields to focus particle beams. To power the IT magnets from the grid, a multistage power supply with an intermediate 24-V battery pack is being considered. In such topology, a low-voltage high-current dc/dc converter operating with a very high step-down ratio is required for the final conversion stage. In this work, an interleaved multiphase series capacitor buck converter is proposed to feed the IT magnets from the battery pack. A novel voltage regulation approach that ensures the current balance between the paralleled series capacitor cells is also proposed, where one cell is responsible for the output voltage regulation, while the remaining cells are current-regulated. A balanced current sharing between the series capacitor cells is achieved, when the current-controlled cells are referenced by the actual current of the first one. The proposal is theoretically analyzed and experimentally validated in a six-cell 1000-A prototype unit. [ABSTRACT FROM AUTHOR]

A circuit structure, topological family, and unipolar phase-shift SPWM master-slave power distribution energy management control strategy (EMCS) of the single-stage Buck type multi-input high-frequency (HF) link's inverters with multiwinding time-sharing power supply are proposed in this article, in order to reduce the power conversion stage, volume and weight, and increase conversion efficiency and reliability. The key technologies of this kind of inverter, such as circuit structure and topological family, EMCS, power supply mode (PSM), and steady-state principle characteristics, are deeply studied. The circuit structure is composed of multiple isolated HF inverting bridges, a HF transformer with multi-input single-output, a cycloconverter and an output LC filter. The EMCS is to generate the bipolar tristate multilevel SPWM waves by phase-shift between the right arm and the left arm of multiple HF inverting bridges; the cycloconverter demodulates it into the unipolar tristate multilevel SPWM wave, and performs zero voltage commutation. The experimental results of the designed and developed 1kVA multi-input inverter prototype have shown it has the advantages of single-stage power conversion, HF electrical isolation, high conversion efficiency, small volume and weight, high reliability, stable output voltage, multi-input source master-slave power distribution, and smooth switching of different PSMs. [ABSTRACT FROM AUTHOR]

This study presents an embedded system in hardware based on mutual information measurements and artificial neural networks for the stator winding short-circuit diagnosis of three-phase induction motors (TIMs) with a line-connected sinusoidal power supply. The methodology employs an information theory measure to extract the most relevant characteristics of the current signals of TIM phases A and B. These data are presented to a multilayer perceptron neural network that performs the pattern classification. Experimental tests with different machine operating conditions validate the robustness and efficiency of the proposed methodology. [ABSTRACT FROM AUTHOR]

Rechargeable batteries are becoming ubiquitous in wide ranging applications including electric vehicles (EVs), consumer electronics, communication devices, aerospace equipment, household equipment, and power tools. A battery management system (BMS) is an integral part of every battery pack, tasked with ensuring the safety, efficiency, and reliability of its performance. When a battery is connected to a power supply for charging, it is the BMS that decides how much current is allowed into the battery according to various criteria, such as the reduced charging time and extended state of health (SOH). Li-ion rechargeable batteries are notorious for their susceptibility to over-voltage and undervoltages exposure; consequently, it is the responsibility of a BMS to protect the battery cell from exposure to extreme conditions, thus preserving its quality and reliability for longer time. [ABSTRACT FROM AUTHOR]

This brief presents a fully integrated low-power, low noise bandgap reference (BGR) with load driving capability. With the BGR core resistors functioning as the feedback network of the current sourcing power transistor, the proposed BGR saves chip area, reduces noise while supporting current load driving. The circuit is implemented in two different processes for performance comparison, namely the $0.18\mathbf {\mathrm {\mu }}\text{m}$ RF CMOS and the BCD mixed-signal CMOS processes. Measurement results from chip samples of the two processes show similar performances, with an average temperature coefficient (TC) of 27.1ppm/°C over $\mathbf {-} 40\mathbf {\mathrm {\sim }} 125\mathbf {^{\circ} }\text{C}$ at a 1.8-V supply. The corresponding measured coefficient of variation ($\mathbf {\mathrm {\sigma }}/\mathbf {\mathrm {\mu }}$) is around 0.3%, and the load driving capability can be up to $800\mathbf {\mathrm {\mu }}\text{A}$. By reusing the feedback resistors, the chip prototype achieved a low noise density of $1.92~\mathbf {\mathrm {\mu }}\text{V}/\surd $ Hz, 285nV/ $\surd $ Hz and 4nV/ $\surd $ Hz at 10 Hz, 10 kHz and 100 kHz, respectively, while consuming a quiescent current of 396nA. The measured power supply rejection (PSR) is −39dB at 5Hz and −45dB at 1MHz. The influence of load current on PSR has also been analyzed and verified. [ABSTRACT FROM AUTHOR]

The grid-connected inverter is a key device in the renewable energy power generation system and large-scale energy storage system, which the operational stability and reliability are the basis for the efficient and safe application of electrical energy. A real-time fault diagnosis method of a three-phase for grid-connected application combining a mixed logic dynamic (MLD) model and finitecontrol set model predictive control (FCS-MPC) is proposed. This paper not only realizes the open circuit fault diagnosis and location of the switching devices in the main power circuit, but also discusses the threshold issues and post-fault operations. The advantage of the proposed method is that it directly uses the control data and measurement signals of the controller without extra sensors and calculation, which will shorter the fault diagnosis time and occupy less calculation resource of the main processor. Simulation results illustrate the quickness of the fault identification and accurate position with robustness to the interference of the diagnosis method. Finally, the effectiveness of the diagnosis method was verified by a 1500 W experimental prototype in a laboratory. [ABSTRACT FROM AUTHOR]

A nonisolated integrated multiple output synchronous buck converter is proposed in this article to cater the auxiliary power supply requirements of e-mobility. The converter provides independently controlled multiple outputs with reduced switch count as compared to conventional separate buck converters as well as conventional synchronous buck converter. The operating principle and working of the proposed converter are discussed in detail for better understanding. As the dynamic behavior of the converter is similar to the conventional buck converter, a simple controller is designed and implemented in this work. The converter is simulated in MATLAB-Simulink. A laboratory prototype of single input–quadruple output (SIQO) converter is developed and operated under closed loop condition to validate and demonstrate its advantages. The prototype is developed by designing two inductors on a single core for increased compactness and reduced cost of the converter. Each output of the converter can be independently controlled by varying the duty ratio of the related switch, thereby eliminating the effective cross regulation problem. The efficiency of the proposed SIQO converter is 93.6%, with four output ports, which is higher than its category of converters reported earlier. A significant improvement in the calculated efficiency is observed with the replacement of conventional switches and diodes of the converter by SiC switches (96.1%). [ABSTRACT FROM AUTHOR]

DC circuit breaker is the key equipment to deal with the interruption of short-circuit current. Compared with the mechanical switch, the solid circuit breaker and the hybrid circuit breaker using the semiconductor device to interrupt the short-circuit current exhibit superiorities in response duration and arc-less characteristics. Massive power devices controlled by corresponding gate drivers which make the semiconductors-based dc circuit breaker bulky and costly are required to withstand the high dc-bus voltage. In this article, the master−slave concept based modular circuit breaker is proposed to simplify the gate driver topology. Only one single gate driver is required to control highly compact modular submodules consisting of power devices, passive components, and diodes. Moreover, the proposed topology can be easily implemented with high flexibility and low cost. Specifically, the gate control function and voltage equalization for series-connected devices can be realized reliably. The master−slave concept and operation principle of the proposed topology are elaborated and the effectiveness has been demonstrated by both simulation and experimental test. [ABSTRACT FROM AUTHOR]

This article proposed the concept of monopolar fault reconfiguration for bipolar dc distribution system realized with Bipolar Half Bridge (BiHB) converter. Monopolar fault reconfiguration oriented from bipolar high voltage direct current (HVdc) transmission grid. For dc distribution, the operation aim is to provide uninterrupted power supply to critical load under monopolar fault. It requires interfacing circuit with fault-tolerant capability as well as control design considering both bipolar and monopolar working mode. The proposed BiHB converter achieves mode switching by reconfiguring the converter switching pattern. Considering both monopolar and bipolar working mode, a bipolar modulation method is proposed for coordinate circuit design. Key influence factors relating to the transient voltage spikes have been identified, including the fault detection delay and the modulation method. Besides, to suppress the voltage spikes caused by monopolar fault, feed-forward compensation is adopted for smooth mode transition. The proposed BiHB converter and control strategy have been comparatively evaluated under fault protection and restoration. Uninterrupted power supply of load has been attained, in validation of the proposed monopolar fault reconfiguration concept. [ABSTRACT FROM AUTHOR]

For independent islands with poor grid and traffic facilities, the stand-alone photovoltaic/wind/battery microgrid (SWPBM) is an effective way to solve its power supply poser via integrating its local renewable energy sources. This article proposes a size planning scheme based on power prediction to ensure the economy, reliability, and environmental-friendly of SWPBMs. A new objective function covering the dynamic investment payback period and excess energy is designed to achieve the tradeoff between the economy and the utilization rate of RE in SWPBMs. Strict uninterrupted power supply and state of charge range of battery are taken as constraints of optimal problem to improve the reliability of power supply of the system. Moreover, a long short-term memory based power prediction method with prediction error correction is proposed to capture the uncertainty of PV, wind turbine, and load power, which is conducive to making a reliable size planning decision. A nested multiobjective particle swarm optimization algorithm, whose computational complexity is greatly reduced by grouping the net load, is implemented to solve the multiobjective optimal sizing problem. Finally, the feasibility of the proposed size planning method for SWPBM is verified by the simulation results. [ABSTRACT FROM AUTHOR]

To improve the consumption of renewable energy and to meet complex load demands. A model of a multi-terminal flexible DC distribution network with multiple overhead branch lines is constructed. Aiming at frequent non-permanent faults of overhead lines, a fast pilot protection scheme is proposed to cover the whole fault process. Using the hybrid DC circuit breaker (HDCCB) action as the boundary mark, the fast pilot protection can be divided into two phases: post-fault and fault restart. The first phase highlights rapidity, sending a trip command to HDCCB within 1-2 ms after the fault. The second stage emphasizes reliability, and points out that the data of the whole fault process should be fully utilized, and to fully excavate the characteristics of fault current. A multi-time scale and multi-criteria fusion protection scheme is proposed, which can effectively improve the reliability of fault area identification. Finally, a corresponding model was built based on PSCAD, a large number of simulation tests and robustness analysis proved that the proposed fast pilot protection scheme is feasible. [ABSTRACT FROM AUTHOR]

Transformer-customer relationship identification refers to the determination of the physical connection relationship of electricity end-customers and their corresponding transformers. Such connection relationship is critical for distribution utilities to maintain their end-customer profiles. However, management of transformer-customer relationship becomes one of the most emerging challenges due to large number of end-customers and lack of measurement devices in low-voltage distribution systems. To address the above issue, this paper proposes an end-customer data-driven method to identify transformer-customer relationship in low-voltage distribution grid by utilizing the customer field data obtained from advanced metering infrastructure. Specifically, the incidence convolution identification method is proposed to build up the unique mapping relationship between end-customers and their transformers based on the principle of energy conservation. Then the voltage correlation maximization model based on Markov Random Field is proposed, where the voltage correlation matrix is exacted and combined with the adjacency matrix to establish an optimization model to correct the potential abnormal transformer-customer relationship. Finally, the effectiveness of the proposed method is verified by using practical utility tests. [ABSTRACT FROM AUTHOR]

In this article, the slow-scale instability occurring in the three-level T-type inverter with a passive memristive (3LT2IPM) load is investigated. The average model of the 3LT2IPM, whose coefficient matrix is nonlinear periodic time-varying, is constructed, both harmonic balance method used to calculate the approximate solution of the average model and Floquet theory used to identify the circuit dynamic states are applied to explore the mechanism of the slow-scale instability emerging in the 3LT2IPM. Theoretical results indicate that the slow-scale instability of the 3LT2IPM is caused by Hopf bifurcation emerging in a region where the frequency is higher than line frequency but much lower than switching frequency. Also, the conditions of three theoretical parameters that make the theoretical analysis results as accurate as possible are presented. Different parameters impact on the stability boundary of the 3LT2IPM in various design parameter spaces are discussed, and the Floquet multiplier sensitivity is analyzed to identify key parameters for the stability of the 3LT2IPM, which are helpful to guide parameter adjustment of the 3LT2IPM to ensure its stable operation in practice. Finally, hardware experiment is established and experimental verification is provided. Physical experiments agree well with simulations, which together demonstrate the correctness of theoretical analysis. [ABSTRACT FROM AUTHOR]

High-efficiency high voltage dc power supply is the core equipment for magnetron in the microwave industry. This article presents an input-parallel output-serial modular high isolated resonant converter for the magnetron. However, the high stray capacitance of the high isolation transformer brings some challenges, such as high turn-off current, longer dead time, increasing gain, and transformer optimization. A simplified model including the stray capacitances is built to deal with these problems, and the minimum turn-off current is derived after the detailed time-domain analysis. The appropriate deadtime and the maximum magnetic inductance needed for the proposed converter are obtained with the minimum turn-off current. Then, a 15 kW, 60 kV isolation multiple-windings output transformer is designed and optimized for the converter. The insulation design, core shape, losses, and parasitic parameters are calculated thoroughly. The Pareto optimization process optimizes the switching frequency and the transformer's turns to obtain higher efficiency and a more stable gain. The finite element method and time-domain simulation verified the optimized design results. Finally, a 0.8/2.5 kV, 15 kW all-SiC dc–dc converter module is developed to validate the proposed design. The results indicate that the module efficiency is as high as 98.6%. [ABSTRACT FROM AUTHOR]

Flow control technology using dielectric barrier discharge plasma actuators stimulated by a sinusoidal alternating current (AC) high-voltage power supply has been studied explosively during the last two decades in the aerospace area for promoting the aerodynamics performance of the airplane. For the purposes of uncovering the controlling mechanism and enhancing the control effect of plasma actuators, the formation mechanism of the wall jet produced by plasma actuators in still air is studied by using a high-frequency particle image velocimetry system, a pressure-field microphone, and a high-accuracy phase-lock image freezing Schlieren technique. The discharge of the plasma actuator is mainly involved in the streamer discharge and the glowlike discharge during one sinusoidal AC period. It is found that the acoustic streaming flow generated by the plasma actuator lifts the airflow, and the body force generated by the plasma actuator pushes the airflow, during the streamer discharge stage. In addition, the airflow is drawn by the entrainment and pushed by the induced body force, respectively, during the glowlike discharge stage. Based on the body force and acoustic streaming flow, the influences of the plasma actuator on quiescent air are summarized as lift-push-push behavior. [ABSTRACT FROM AUTHOR]