Three-phase Switching Research Articles

Intelligent Controller Based on Artificial Neural Network and INC Based MPPT for Grid Integrated Solar PV System

Solar photovoltaic (PV) systems have become an integral part of today's advanced energy infrastructure due to its low kinetic energy, its abundance availability, and its freedom from human interference. Solar PV systems have the potential to greatly reduce our reliance on fossil fuels, but their intermittent nature means they cannot provide a constant source of electricity. The system's security should be well thought out, and it should be able to withstand a lot of abuse. The current energy system faces a significant difficulty in ensuring continuous supply. In this study, a three-phase, two-stage photovoltaic system that is managed by artificial neural networks (ANN). A DC-DC boost converter with maximum power point tracking (MPPT) based on the incremental conductance (INC) method is incorporated in the first stage. In the next step, an ANN-based controller optimizes the performance of a three-phase switching PWM inverter that is connected to the grid by controlling currents along the d-q axis. Comprehensive simulations were carried out using MATLAB or Simulink to evaluate the system's performance under various illumination and temperature conditions. Results show that the suggested approach outperforms the baseline in a number of areas. Better dynamic reactions, accurate tracking of reference currents within permissible bounds, and quick settling periods after startup are all displayed by it. These findings show that our method has the potential to greatly improve the efficiency and dependability of solar PV systems. The results of this study have implications for renewable energy in general and present a viable path toward enhancing the resilience and sustainability of energy infrastructure.

Improved Finite-Time Control for Circulating Current Suppression of Multiparalleled Rectifiers

Multi-paralleled three-level rectifiers (MP3LRs) have the advantages of higher-power rating and higher reliability. However, the zero-sequence circulating current (ZSCC) will occur when MP3LRs are connected to a common dc bus, which will distort the grid current, and threaten the safe and reliable operation of MP3LRs. Significantly, the ZSCC suppression of the MP3LRs is rarely studied. To overcome the limitation, an improved ZSCC suppression method for MP3LRs is proposed in this paper. Firstly, a ZSCC model of the MP3LRs system is established. Secondly, according to the ZSCC model, the ZSCC controller based on “Finite-time control + Feedforward” is designed, and the strict theoretical proof of system stability is carried out. Thirdly, this method is realized by using the output of ZSCC controller to modify the three-phase switching time of multiple rectifiers (2nd to Nth rectifiers). Consequently, the method proposed in this paper can suppress the ZSCC of MP3LRs, completely. Compared with the conventional ZSCC suppression methods, the proposed method has better ZSCC suppression performance and stronger anti-interference capability. Meanwhile, it does not increase any hardware cost. Finally, simulation and experimental results verify the effectiveness of the proposed method.

Studies on Three-phase Imbalance Treatment Based on Beidou communication and Commutation Switch

In this paper, genetic algorithm and commutation switch based three-phase imbalanced distribution network are studied. A genetic algorithm-based commutation switch three-phase imbalance management strategy was developed, and the three-phase current distribution station area was established. A mathematical model was developed for the multi-objective optimal commutation based on the minimum imbalance degree and the minimum switching times of the low-voltage load online automatic commutation device during the commutation process. Additionally, the real-time online governance control strategies were balanced. Finally, the effectiveness of the proposed method was verified using simulation studies.

MAIN ASPECTS OF IMPLEMENTATION OF CHARGING STATIONS FOR ELECTRIC TRANSPORTS IN LOGISTICS

The paper analyzes and compares charging stations for small electric vehicles, including fast and slow boats, electric cars and their components. The analysis of charging modes of electric vehicles showed that four internationally standardized modes are used, three of which use alternating current with single-phase and three-phase switching and only one – direct current. When charging on direct current, the fastest charging is provided. There are three main options for connecting the electric vehicles to the charging station: by means of a special power cable; by means of a pantograph from bottom to top and from top to bottom; wirelesses connection. There are four standardized cases of connecting charging stations to electric vehicles. Three cases of cable connection can be used on alternating current, only the third case – on direct current, and the fourth case – when wirelessly charging an electric vehicle. A comparison of existing types of connectors for charging electric vehicles has shown that the standardized interface between the charging station and the electric vehicle remains one of the most acute problems.

A Three-Phase Multiplexing Arm Modular Multilevel Converter With High Power Density and Small Volume

Modular multilevel converter (MMC) faces challenges ofcost and footprint in medium and high voltage grid applications. By adding a three-phase switching bridge on the basis of MMC, this article proposes a three-phase multiplexing arm modular multilevel converter (TPMA-MMC) with high power density and small volume. The multiplexing principle for TPMA-MMC is investigated, showing the multiplexing arm can be multiplexed for one-third fundamental period. After that, the subsection modulation scheme is further proposed for energy balance purpose. Compared with MMC, the number of submodules (SMs) and power devices are reduced by 22.8% and 13.83%, respectively, resulting in lower construction cost. Meanwhile, the SMs’ capacitance and the total capacitor energy storage of TPMA-MMC reduce greatly with the subsection modulation, which can greatly reduce the footprint and improve the power density. Moreover, the proposed TPMA-MMC outperforms the MMC in terms of efficiency. Finally, the topology and proposed modulation scheme are verified by simulation and experimental results.

COMPARATIVE ANALYSIS OF TECHNICAL CHARACTERISTICS OF CHARGING STATIONS OF ELECTRIC VEHICLES

The article analyzes and compares charging stations for electric vehicles and their components. The analysis of charging modes of electric vehicles showed that four internationally standardized modes are used, three of which use alternating current with single-phase and three-phase switching and only one – direct current. When charging on direct current, the fastest charging is provided. There are four standardized cases of connecting charging stations to electric vehicles. Three cases of cable connection can be used on alternating current, only the third case – on direct current, and the fourth case – when wirelessly charging an electric car. Analysis of the principles of use of charging stations showed that they classify portable, wall, and stationary stations. National standards introduce road signs for electric vehicles, and a European standard establishes harmonized identifiers for the power supply of electric vehicles. There are some standardized protocols for the interaction of the charging station and the control server, which are designed to optimize energy resources and energy production systems. A comparison of existing types of connectors for charging electric vehicles has shown that the standardized interface between the charging station and the electric vehicle remains one of the most acute problems. Recommendations on approaches to metrological support of charging stations are formulated. The issue of international and regional standardization of electricity meters of direct current for use in charging stations remains relevant. International standards are transformed into relevant European standards without changes. However, in some cases, it is necessary to develop a special European standard, in particular for meters of active electrical energy of the direct current.

The DC side soft switching three-phase voltage inverters

The DC side soft switching three-phase voltage inverters

Implementation of Grid Synchronization Methods on a Real Time Development System

Abstract The paper presents a study regarding the implementation of two representative grid synchronization methods, intended to be used in the control structure of a three phase switch mode voltage rectifier. The methods considered are the Synchronous Reference Frame Phase Locked Loop (SRF PLL) and the Double Synchronous Frame Phase Locked Loop (DSRF PLL), respectively. These synchronization methods have been compared on a real time development system type dSpace 1104 from the point of view of their performance in case of an unbalanced mains voltage system. Finally, the influence of the chosen grid synchronization method on the performance of a synchronous reference frame controlled three-phase switch mode voltage rectifier is studied by simulation, and better results are demonstrated to be provided by the use of the DSRF PLL.

DRNN Robust DTC for Induction Motor Drive Systems Using FSTPI

In this paper, a self-tuning PI speed controller based on diagonal recurrent neural network is (DRNN) investigated and simulated to increase the robustness of the direct torque control (DTC) scheme for three-phase low-power IM drive system using a Four Switch Three-Phase Inverter (FSTPI). The drive is subjected to different system inputs and disturbances, step changes in speed under different load conditions, abrupt loading at high speed and speed reversal. Furthermore, the robustness of the controller is evaluated by varying motor parameter, stator resistance and moment of inertia. A comparison of classical and self-tuning PI speed controllers was presented to determine the effectiveness of the proposed controller. It is concluded based on simulation results using Matlab/Simulink. that the self-tuning PI speed controller provides the best performance by reacting rapidly and adaptively.

Duty VV-MPTC for Post-Fault Eight Switch Three-Phase Inverter Fed Induction Motor Drives With Reduced Neutral Point Voltage Fluctuation

This article proposes a novel duty ratio regulated virtual voltage vector (VV) model predictive torque control (MPTC) strategy for post-fault eight switch three-phase inverter fed induction motor drive with reduced neutral point (NP) voltage fluctuation. The proposed method contributes to substantially improve the steady-state torque control performance under post-fault conditions. Furthermore, compared with the conventional MPTC, it reduces the torque ripples as well as the NP voltage fluctuations. The mathematical model of eight-switch three-phase post-fault inverter fed induction motor is presented. Based on this, the synthesis of virtual VV is analyzed. Simulation and experimental results are presented to validate the effectiveness of the proposed method.

Improved Model Predictive Control With New Cost Function for Hybrid-Inverter Open-Winding PMSM System Based on Energy Storage Model

Conventional model predictive control (C-MPC) usually leads to considerable torque and current ripples since only one voltage vector is applied. In addition, the C-MPC applied in the hybrid-inverter) driven open-winding permanent magnet synchronous motor (OW-PMSM) suffers from complex tuning work of weighting factors and iterated evaluation work of all potential vectors because the capacitor voltage constraint in cost function is related to the switching states. In this article, an improved three-vector MPC based on energy storage model is proposed for the HI-OW-PMSM system. Firstly, a new prediction model of dc-link capacitor voltage based on energy storage model is proposed thus the capacitor voltage constraint is decoupled to the three-phase switching states. Furthermore, a novel restructured cost function without weighting factors can be obtained. Accordingly, by using the new prediction model and the novel cost function, the voltage reference can be easily obtained and a three-vector based prediction strategy without sector division can be carried out to achieve optimal voltage vectors selection and duty cycle calculation. Therefore, the system performance is improved and the calculation burden is also reduced. Finally, comparative experimental studies are carried out to validate the effectiveness of the proposed improved three-vector MPC method.

AI based Vector Control Method for BLDC Motor with Multi Switch Three-Phase Topology

Brushless direct current (BLDC) Motors are extensively used because of their characteristics. Such characteristics are high dynamic response and high-power density. BLDCM control system is a nonlinear, multi-variable, strong-coupling system. In this paper it is proposed that a neural network controller is used for the five level switch of the BLDC motor to enhance the power factor and reduce the current distortions with respect to its rise time, startup torque. This method is also done in comparison with the PID controllers. The working principle of the BLDC is with the help of five-switch control scheme can be implemented here. The different values of load were used to consider the total operation of the BLDC motor is to be controlled. After the completion of the training and testing of the neural network, it might be maintain the constant load values and its variables. To calculate the duty ratio of the DC-DC converter, it will be adjusted to regulate the speed of the BLDC motor. However the DC link of the five switching inverter is used here for the boosting of the voltage. The effectiveness of the proposed control technique can be realized with help of the speed sensor. Various tests have been conducted in the simulation the proposed technology is the robust technology and it is proven that very effective and suitable control technique.

Universal MHD device for automation of casting control of aluminum

The article proposes an MHD device designed to automate the management of casting aluminum melt from a stationary mixer. The product is made on a modular basis, similar to an induction detachable unit, has three magnetic cores with windings. The design of the MHD device, the location of the magnetic cores, and the features of connecting the windings to the network turn it into a universal unit. The location of the casting trough inside the closed cores allows the device to be used as an MHD pump for aluminum melt. Methods of connecting the windings make it possible to realize the function of dosing the melt using automated process control systems. Pumping the melt through the chute when placing the module between two sockets ensures stirring of the melt in the mixer. The use of a group of single-phase transformers in three-phase switching ensures the movement of aluminum in the channel by creating traction forces in the melt. The presence of windings, allowing for opposition, puts the electromagnetic module into transformer-inductor mode, improving energy efficiency in traction modes, providing melt heating beyond the furnace and maintaining aluminum temperature.

Iris Sommer—unravelling biological mechanisms of psychiatric disorders

When Iris Sommer retires, she wants to leave behind a new treatment for psychiatric illness that really makes a difference. “I realise this is easier said than done,” she tells The Lancet Psychiatry. “In neurology, we understand underlying mechanisms so much better than before. But in psychiatry, we are still trying to understand even the basic mechanisms behind many conditions.” Directed pharmacological therapy of ambiguous genitalia due to an androgen receptor gene mutationWe report a 46, XY infant with an M807T mutation in his androgen receptor that abrogated cellular responses to testosterone, but not to dihydrotestosterone (DHT), resulting in ambiguous genitalia. Treatment with a topical DHT gel restored male genital development allowing the infant to be reared in accordance with his chromosomal sex. Full-Text PDF Amisulpride and olanzapine followed by open-label treatment with clozapine in first-episode schizophrenia and schizophreniform disorder (OPTiMiSE): a three-phase switching studyFor most patients in the early stages of schizophrenia, symptomatic remission can be achieved using a simple treatment algorithm comprising the sequential administration of amisulpride and clozapine. Since switching to olanzapine did not improve outcome, clozapine should be used after patients fail a single antipsychotic trial—not until two antipsychotics have been tried, as is the current recommendation. Full-Text PDF Prosopometamorphopsia and facial hallucinationsIn July, 2011, a 52-year-old woman presented to our psychiatric outpatient clinic in The Hague with a life-long history of seeing people's faces change into dragon-like faces and hallucinating similar faces many times a day. She could perceive and recognise actual faces, but after several minutes they turned black, grew long, pointy ears and a protruding snout, and displayed a reptiloid skin and huge eyes in bright yellow, green, blue, or red. She saw similar dragon-like faces drifting towards her many times a day from the walls, electrical sockets, or the computer screen, in both the presence and absence of face-like patterns, and at night she saw many dragon-like faces in the dark. Full-Text PDF

DC‐link capacitor voltage balance strategy of independent double three‐phase common bus five‐level NPC/H‐bridge inverter based on finite control set

This study aims at the DC-link capacitor voltage imbalance problem of independent double three-phase common bus five-level neutral point-clamped/H-bridge inverter, which is applied to an electromagnetic launch system under instant high-power and high-current conditions. First, the traditional method of voltage balance strategy based on redundant vectors is described, and the key factors leading to the DC-link capacitor voltage fluctuation is analysed in detail. Second, the objective function is constructed to predict the variation trend of DC-link capacitance voltage difference. Third, an optimised voltage balance strategy is proposed. At first, the optimised strategy calculates the variation trends of the voltage difference for all three-phase switch vector combinations. Then, the results make up a voltage balance finite control set. At last, compare the results in the set to select the vector combination corresponding to the minimum variation for output. Finally, tested by the semi-physical real-time simulation platform, and the proposed optimised voltage balance strategy is verified effective for improving DC-link capacitor voltage imbalance and inhibiting the voltage difference fluctuation.

Simple Commutation Torque Ripple Reduction Using PWM With Compensation Voltage

In this article, a combination of a two- and three-phase switching method to reduce switching loss is presented. In the conduction region, the conventional two-phase switching topology is used to reduce switching loss. On the other hand, in the short commutation region, the proposed modified three-phase switching strategy that incorporates a voltage compensation method is used to reduce torque ripple. The design of the proposed torque compensation method is based on the back electromotive force (EMF). The goal is to optimize the phase current slope by using the phase voltage and back EMF at the start and end point of the commutation region. Assuming that the slope of the back EMF in the commutation region is almost the same as a sinusoidal waveform, a proper pulsewidth modulation duty ratio can be determined to control the current slope. Experiments with a practical brushless dc motor and drive were performed to verify the performance of the proposed method.

Electromagnetic Performances and Main Parameter Sensitivity Effect on Unbalance Magnetic Flux in a New Single-Phase FEFSM with Segmental Rotor

Three-phase field excitation flux switching motor (FEFSM) with salient rotor structure has been introduced with their advantages of rotor easy temperature elimination and controllable FEC magnetic flux. Yet, the salient rotor structure is found to lead a longer magnetic flux path between stator and rotor parts, producing a weak flux linkage along with low torque performances. Hence, a new structure of single-phase FEFSM using segmental rotor with non-overlap windings is proposed with advantages of shorter magnetic flux path, light weight and robust rotor structure. Analysis on fundamental magnetic flux characteristics, armature and FEC magnetic flux linkages, cogging torque, back-Emf, various torque capabilities, refinement of unbalance magnetic flux, and torque-power versus speed characteristics are conducted using 2D FEA through JMAG Designer version 15. The results show that magnetic flux amplitude ratio has been improved by 41.2% while the highest torque and power achieved are 1.45 Nm and 343.8 W, respectively.

Robust Optimal Allocation of Decentralized Reactive Power Compensation in Three-Phase Four-Wire Low-Voltage Distribution Networks Considering the Uncertainty of Photovoltaic Generation

Due to the unbalanced three-phase loads, the single-phase distributed photovoltaic (PV) integration, the long feeders, and the heavy loads in a three-phase four-wire low voltage distribution network (LVDN), the voltage unbalance factor (VUF), the network loss and the voltage deviation are relatively high. Considering the uncertain fluctuation of the PV output and the load power, a robust optimal allocation of decentralized reactive power compensation (RPC) devices model for a three-phase four-wire LVDN is proposed. In this model, the uncertain variables are described as box uncertain sets, the three-phase simultaneous switching capacity and single-phase independent switching capacity of the RPC devices are taken as decision variables, and the objective is to minimize the total power loss of the LVDN under the extreme scenarios of uncertain variables. The bi-level optimization method is used to transform the robust optimization model with uncertain variables into bi-level deterministic optimization models, which could be solved alternately. The nonlinear programming solver IPOPT in the mature commercial software GAMS is adopted to solve the upper and lower deterministic optimization models to obtain a robust optimal allocation scheme of decentralized RPC devices. Finally, the simulation results for an actual LVDN show that the obtained decentralized RPC scheme can ensure that the voltage deviation and the VUF of each bus satisfied the secure operation requirement no matter how the PV output and load power changed within their own uncertain sets, and the network loss could be effectively reduced.

Three phase PWM converter using PI and fuzzy with hysteresis current controller

The research work presents hysteresis current controlled three-phase PWM converter. The switching control is applied on three-phase bi-directional switches, to attain sinusoidal input current at unity power factor and constant output voltage. The dc-link voltage is controlled by outer loop fuzzy controller and PI controller. The converter can be used for regeneration or bi-directional power flow. The converter is especially suitable for mid to low power application (i.e., 5-15 kW).The bi-directional switches operate at low frequency, crossover zero voltage (at turn-on) and conduct for 1/12th of line voltage cycle. The THD analysis of the controlled input phase current shows significant reduction in the THD as compared to the uncontrolled input phase current. The dc-link voltage follows the reference value.

Coded Switching Scheme for Monitoring the Operation of Distribution Capacitors

A novel scheme is proposed to monitor the operation of capacitors scattered in MV distribution systems. It first codes each capacitor with a distinctive switching character by setting a unique combination of a three-phase switching order and time interval. As a result, the transient of the three-phase reactive power during capacitor switching will appear in a unique way. Then, the reactive power disturbances monitored in the substation are decoded to identify which capacitor is being switched on and off . A detailed decoding method is developed to realize this identification without being impacted by the switching interference of loads and other reactive power compensation devices. Moreover, the implementation of the proposed scheme in the field is elaborated, and the resultant three-phase voltage unbalance is analyzed in this paper. Compared with existing methods, this scheme only requires one power quality monitor located at the substation to monitor the operations (energizing or de-energizing) of downstream distribution capacitors without extra communication devices. The operation information is valuable for tackling power quality problems caused by capacitor switching and optimizing the distribution grid operation.