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A common 400 V dc bus for industrial motor drives advantageously allows the use of high‐performance 600 V power semiconductor technology in the inverter drive converter stages and to lower the rated power of the supplying rectifier system. Ideally, this supplying rectifier system features unity power factor operation, bidirectional power flow and nominal power operation in the three‐phase and the single‐phase grid. This paper introduces a novel bidirectional universal single‐/three‐phase‐input unity power factor differential ac‐dc converter suitable for the above mentioned requirements. The basic operating principle and conduction states of the proposed topology are derived and discussed in detail. Then, the main power component voltage and current stresses are determined and simulation results in PLECS are provided. The concept is verified by means of experimental measurements conducted in both three‐phase and single‐phase operation with a 6 kW prototype system employing a switching frequency of 100 kHz and 1200 V SiC power semiconductors. Considering economies of scale, next generation PFC rectifiers for the supply of 400 V dc distribution systems should feature nominal power operation in both a three‐phase and a single‐phase grid. This paper proposes a novel PFC rectifier topology with identical component stresses and control for both single‐ and three‐phase operation.

This study focuses on reduced-order dynamical modelling of droop controlled converter-based DC sub-microgrid (MG) in a hybrid AC/DC MG. In hybrid MGs, electrical power is exchanged between the AC and DC sub-MGs by a bidirectional AC/DC converter. The authors aim to develop a comprehensive reduced-order dynamical model for the DC side in this part, incorporating standard classes of electrical loads including constant current, constant power, and constant resistance loads. Furthermore, dynamical behaviour of the power exchange between the AC and DC sub-MGs is modelled, considering that the bidirectional power converter controller aims to equalise the load ratios of AC and DC sub-MGs in order to facilitate overall decentralised control over the hybrid MG. Analytical derivations of steady-state values of main variables are given and the overall dynamical and algebraic equations are determined. In order to validate the developed model, a hybrid MG is implemented in PSCAD. Then, the proposed model for the case study is implemented in Matlab/Simulink and the results are compared with the PSCAD outputs. The comparative results show the validity of the developed reduced-order comprehensive model. The reduced-order models are preferred in designing observers such as model-based fault detection and diagnosis observers.

With the rapid development of the electric vehicle (EV) industry, charging facilities for electric vehicles are gradually improving, thus meeting the demand for fast and safe charging. This paper comprehensively describes the current development status and future development trend of EVs and their charging infrastructure and analyzes in detail the EV fast-charging system architecture according to the AC/DC coupling configuration. The topologies and control techniques of the front AC/DC converter and rear DC/DC converter for the charging system are discussed, providing a reference for the future design of hundred-kilowatt level and above fast-charging systems for EVs. In addition, this paper summarizes the EV charging interface and the charging specifications applicable to the hundred-kilowatt power fast-charging system, as well as the impact of fast charging on power batteries, and emphasizes that high-power fast-charging technology is an inevitable trend for the future development of electric vehicles.

This study focuses on reduced-order dynamical modelling of droop-controlled inverter-based low-voltage AC sub-microgrid in a hybrid AC/DC microgrid. The authors aim to develop a comprehensive reduced-order model for the low-voltage AC side in this part. The reduced-order models are preferred in real-time calculations. In hybrid microgrids, electrical power is exchanged between the AC and DC sub-microgrids by a bidirectional AC/DC converter. The distributed energy resources are connected to the main AC bus through power inverters. Voltage and frequency commands are generated by droop controllers for each inverter. For the main AC bus, equations describing voltage magnitude and frequency are derived. Steady-state values of the phase angles and injected power of the inverters are calculated. The overall non-linear dynamical and algebraic equations are derived for the low-voltage AC side, and then linearised around the operating point. To validate the developed model, a hybrid microgrid is implemented in PSCAD. Then, the proposed model for the case study is implemented in Matlab/Simulink and the results are compared with PSCAD outputs. The comparative results show the validity of the developed comprehensive reduced-order model which can be used in fault detection approaches.

In this study, a DC micro-grid consisting of multiple paralleled energy resources interfaced by both bidirectional AC/DC and DC/DC boost converters and loaded by a constant power load (CPL) is investigated. By considering the generic dq transformation of the AC/DC converters' dynamics and the accurate nonlinear model of the DC/DC converters, two novel control schemes are presented for each converter-interfaced unit to guarantee load voltage regulation, power sharing and closed-loop system stability. This novel framework incorporates the widely adopted droop control and using input-to-state stability theory, it is proven that each converter guarantees a desired current limitation without the need for cascaded control and saturation blocks. Sufficient conditions to ensure closed-loop system stability are analytically obtained and tested for different operation scenarios. The system stability is further analysed from a graphical perspective, providing valuable insights of the CPL's influence onto the system performance and stability. The proposed control performance and the theoretical analysis are first validated by simulating a three-phase AC/DC converter in parallel with a bidirectional DC/DC boost converter feeding a CPL in comparison with the cascaded PI control technique. Finally, experimental results are also provided to demonstrate the effectiveness of the proposed control approach on a real testbed.

Electrical power grids are rapidly evolving into smart grids, with smart homes also making an important contribution to this. In fact, the well-known and emerging technologies of renewables, energy storage systems and electric mobility are each time more distributed throughout the power grid and included in smart homes. In such circumstances, since these technologies are natively operating in DC, it is predictable for a revolution in the electrical grid craving a convergence to DC grids. Nevertheless, traditional loads natively operating in AC will continue to be used, highlighting the importance of hybrid AC/DC grids. Considering this new paradigm, this paper has as main innovation points the proposed control algorithms regarding the role of front-end AC/DC converters in hybrid AC/DC smart homes, demonstrating their importance for providing unipolar or bipolar DC grids for interfacing native DC technologies, such as renewables and electric mobility, including concerns regarding the power quality from a smart grid point of view. Furthermore, the paper presents a clear description of the proposed control algorithms, aligned with distinct possibilities of complementary operation of front-end AC/DC converters in the perspective of smart homes framed within smart grids, e.g., enabling the control of smart homes in a coordinated way. The analysis and experimental results confirmed the suitability of the proposed innovative operation modes for hybrid AC/DC smart homes, based on two different AC/DC converters in the experimental validation.

This study proposes flexible controllers for the interlinking converter (ILC) and interfacing converters (IFCs) used in coupled hybrid AC/DC microgrids (HMGs). Proposed controllers are specifically designed for the multiple stacked bidirectional DC–AC ILCs/IFCs based microgrid outlays, to omit the droop power flow and system stability issues. The ILC and IFC grid supportive converter controllers focus on the wide-spread AC/DC bus parameters control for both DC and AC bus voltage regulation and superfluous power sharing while operating in the grid forming and feeding modes. Proposed controllers minimise the need for the controller parameter tuning as opposed to the conventional controllers used in zonal HMG systems. This makes the system stable for a much wider operating conditions as opposed to the widely used higher-order PLL integrated PQ and dq0 control algorithms. The proposed HMG also integrates the centralised battery energy stack through bidirectional dual active bridge DC–DC converter for achieving the high-power transfer efficiency and omitting the isolation issues between medium-voltage and low-voltage DC buses. The HMG system performance is evaluated using the simulation studies for various strategical operational modes. Further, the proposed controllers have also been tested individually on experimental platform.

This paper describes a prototype of modularized three-phase semiconductor transformer that was developed in the lab for feasibility study. The developed prototype is composed of three units of single-phase semiconductor transformer coupled in Y-connection. Each single-phase unit has multiple units of high-voltage high-frequency resonant AC–DC converter, a low-voltage hybrid-switching DC–DC converter, and a low-voltage hybrid-switching DC–AC inverter. Also, each single-phase unit has two digital signal processor (DSP) boards to control converter operation and to acquire monitoring data. The monitoring system was developed based on LabView by using controller area network (CAN) communication between the DSP board and the personal computer (PC). Through diverse experimental analyses it was verified that the prototype operates with proper performance under normal and sag conditions. The developed prototype confirms the possibility of fabricating a commercial high-voltage high-power semiconductor transformer by increasing the number of series-connected converter modules in high-voltage side and improving the system efficiency with a new switching device such as an SiC device.

This work optimizes the PI controllers of a three-phase bidirectional AC/DC converter to increase Vehicle to-Grid (V2G) system reliability and efficiency. This study aims to solve the limitations of traditional trial-and-error or heuristic tuning methods, which often result in suboptimal performance in dynamic V2G environments. The Grey Wolf Optimiser (GWO) is used to determine optimal controller gains for several objective functions, including Integral Square Error (ISE), Integral Time Absolute Error (ITAE), and Integral Squared Time Error (ISTE). This study shows that a simple, systematically optimised PI controller can compete with more complex techniques in performance. The GWO-tuned controller is closely compared to a standard PI controller and an Adaptive Neuro-Fuzzy Inference System (ANFIS) in MATLAB $ ^{\\circledR} $ ® (2023a) under challenging conditions, such as load step changes and sudden power flow reversals. Offline-optimized benefits are confirmed robust by implementing them on a Xilinx Spartan-6 FPGA hardware prototype. Both hardware and simulated results demonstrate the superiority of the GWO-tuned controller. The proposed approach reduces average error reduction by 15%, grid current Total Harmonic Distortion (THD) by 20%, and DC link voltage surge during load transients from 12.5% to 2.3% compared to typical PI controllers. The GWO-PI controller consistently demonstrates improved dynamic response and robustness, proving its suitability for demanding V2G scenarios.

Harvesting energy by capturing vibration from low frequency energy have been explored extensively. In essence, a single piezoelectric transducer or an array of piezoelectric connections are used to convert kinetic energy into electrical energy in order to produce low frequency energy. In this paper, multi-configuration array piezoelectric connections are used to investigate the performances of different converter circuit types in low energy harvesting applications. This research utilized three pieces of circular piezoelectric sensor to test the combinations of array connection. There are four options for the piezoelectric sensor configuration: parallel (P), series (S), parallel-series (PS), and series-parallel (SP) while the full wave bridge rectifier (FWBR), parallel voltage multiplier (PVM), and parallel Synchronized Switch Harvesting on Inductor (P-SSHI) converter circuit are chosen AC-DC converter circuits. The system is assessed using a variety of load configurations, including 10 kΩ and 1 MΩ with a 3 Hz input frequency. In order to produce the highest possible output of collected power, the observation focuses on identifying the ideal combination of array piezoelectric connections with AC-DC converter. The result shows that 3-Parallel (3P) piezoelectric connection obtained a higher power output among the other types of array piezoelectric which was 5.97μW. The FWBR circuit generated the highest output power with 2.42μW for a combination of piezoelectric sensors array of 3P connection with the AC-DC converter.