Nominal Voltage Research Articles

Dynamic Molecular Investigation of the Solid-Electrolyte Interphase of an Anode-Free Lithium Metal Battery Using In Situ Liquid SIMS and Cryo-TEM.

We use in situ liquid secondary ion mass spectroscopy, cryogenic transmission electron microscopy, and density functional theory calculation to delineate the molecular process in the formation of the solid-electrolyte interphase (SEI) layer under the dynamic operating conditions. We discover that the onset potential for SEI layer formation and the thickness of the SEI show dependence on the solvation shell structure. On a Cu film anode, the SEI is noticed to start to form at around 2.0 V (nominal cell voltage) with a final thickness of about 40-50 nm in the 1.0 M LiPF6/EC-DMC electrolyte, while for the case of 1.0 M LiFSI/DME, the SEI starts to form at around 1.5 V with a final thickness of about 20 nm. Our observations clearly indicate the inner and outer SEI layer formation and dissipation upon charging and discharging, implying a continued evolution of electrolyte structure with extended cycling.

Secure Transmission Method of Power Quality Data in Power Internet of Things Based on the Encryption Algorithm

As a new mobile communication technology in the era of the internet of things, 5G is characterized by high speed, low delay, and large connection. It is a network infrastructure to realize human-computer and internet of things in the era of the internet of things. Power quality data is the efficiency with which a power grid delivers electricity to users and expresses how well a piece of machinery uses the electricity it receives. The waveform at the nominal voltage and frequency is the goal of power quality research and improvement. The power internet of things (IoT) is an intelligent service platform that fully uses cutting-edge tech to enable user-machine interaction, data-driven decision-making, real-time analytics, and adaptive software design. The process by which plaintext is converted into cipher text is called an encryption algorithm. The cipher text may seem completely random, but it can be decrypted using the exact mechanism that created the encryption key.

Control Algorithms for a Bidirectional Wireless Power Transmission System at the Redistribution of Energy Resources in a Group of Ground Robots

Redistributing energy resources within a group of ground robots allows for an increase in the reachable workspace area and expands its functional capabilities. The use of wireless energy transfer systems for exchanging energy resources between ground robots reduces the requirements for positioning accuracy and enhances the reliability of the robotic system. This study examines control and management algorithms for a bidirectional wireless energy transfer system when operating as part of a ground robot. A structural diagram of the bidirectional wireless energy transfer module is proposed for integration into the robot’s control system, built on distributed principles. The developed algorithms take into account the specific features of the circuitry solutions of the bidirectional wireless energy transfer system, implemented using an uncontrolled resonant generator. The proposed solutions are tested on a robotics platform. The experiments focus on the process of replenishing the energy resources of one robot with another robot. Energy is transmitted between robots equipped with the same Li-ion battery, which has a nominal voltage of 7.4 V and a capacity of 5 A•h. The battery is charged from 50 % to 90 % capacity with different positioning accuracies of the robots. When there is a displacement of 4 mm and a distance of 4 mm between the receiving and transmitting coils, the charging time was 48 minutes, which is 5 % longer than the wired charging method. The maximum charging time reached 57 minutes with a distance of 15 mm between the robots. The use of bidirectional wireless power transfer for energy exchange between ground robots or for charging robots at a charging station enhances the autonomy of the group’s operation, as energy transfer can be successfully achieved even with low positioning accuracy. The proposed solutions can be used for battery charging and resource redistribution processes in groups of ground and underwater robots.

Design and Analysis of Battery Management System for Electrical Vehicles

Abstract: The quantity of pollution that is emitted into the atmosphere will only continue to climb as the number of people who drive automobiles powered by internal combustion engines continues to rise. To reduce emissions of greenhouse gases, academics and companies on every continent are now focusing their attention on the research and development of more sophisticated technologies for electric cars. During this investigation, we are going to model and create a two-way power converter for electric automobiles. Batteries, a dc-dc converter, and a dc motor are just a few of the many diverse parts that make up the power electronics module. It is advised that the starting battery be charged to about 90% of its capacity before using the motor mode, which has a discharge current of 44.5 A. The battery stack has a maximum capacity of 100 ampere-hours, and its nominal voltage is 350 volts. This is the greatest amount of energy that it can store. Direct current (DC) machines have the potential to generate up to 250 horsepower, provided that the armature voltage is 500 volts and the field voltage is 300 volts, respectively. The mode of operation for the power converter is determined by the readings of torque that are obtained by the DC machine when it is operating in the motor mode and the generator mode, respectively. The processes of charging and discharging batteries have been monitored and handled in relation to the wide variety of modes of operation that may be found in DC machines. This was done in order to make full use of the capabilities of these machines. The bidirectional dc-dc converter, which may operate in either direction, is managed by a fuzzy logic controller. This allows the converter to work in either direction. It's likely that the converter and controller that's been shown here are all that's needed for charge management and running the motor in electric automobiles.

A Novel Control Scheme for Induction Generator Based Stand-alone Micro Hydro Power Plants

A system comprising of a hydraulic turbine (HT) driven induction generator with excitation capacitor (IGEC) has been proposed for providing electricity to the residents living in remote areas and steep terrains, wherein the grid connection is unviable. The available water resource in such locations is effectively utilized and the load on the generator terminals is set, based on the requirement of the consumer demand. A method has been formulated for the estimation of excitation capacitor and rotor speed for ensuring nominal voltage and frequency at the generator terminals, regardless of variation in the consumer load. This design procedure is based on the analysis of IGEC employing the binary search algorithm (BSA). The logical way of arriving at the range of per unit (pu) speed to start the BSA has also been illustrated. A closed-loop control scheme has also been formulated, by taking generator voltage as the feedback variable and comparing the voltage set limits Vmin and Vmax. Accordingly, a controller action is initiated to add or disconnect the flexible loads. An available mathematical modeling of HT has been modified suitably and by using this model, the functioning of the proposed system with respect to the HT characteristics and generated frequency of IGEC has also been investigated. Using a MATLAB/Simulink software, the successful functioning of the proposed system has been demonstrated with typical operating conditions. The predetermined values and simulated observations are amply supported with the laboratory results conducted on a 3-phase, 3.7 kW IGEC.

Hierarchical control of networked microgrid with intelligent management of TCLs: A case study approach

Significant integration of Renewable Energy Sources (RES) has led to the evolution of an alternative platform with distributed generation and clustered loads in low or medium-voltage distribution networks. However, a standalone microgrid is susceptible to several inconsistencies that may lead to system failure and disruption due to the inherent uncertainty of RES and its intermittent nature. The paper proposes a coordinated and hierarchical control framework with an inverter-fed primary controller to maintain the nominal voltage and frequency with a regulated exchange of ancillary power in networked microgrids. Further, during peak hours, a secondary control mechanism is incorporated through Demand Side Management (DSM). Intelligent aggregation of TCLs has been done based on decision tree models and further controls to maintain the nominal frequency in networked microgrids adhering to IEC 60929 considering different temperature ranges (16–22) °C. A thorough investigation is carried out considering two separate microgrids of critical and non-critical loads respectively (one a hospital microgrid and another residential microgrid) connected through an interlinking converter. The modeling of the test system and analysis of the proposed control mechanism is simulated in MATLAB SIMULINK and real-time validation in the OPAL-RT platform considering several dynamics.

Li-Ion and Na-Ion Intercalation in Layered MnO2 Cathodes Enabled by Using Bismuth as a Cation Pillar

Rechargeability of low-cost MnO2 cathodes in aqueous cells has the potential to be an enabling technology for low-cost (<$50/kWh) grid-scale batteries. This rechargeability is imparted by modifying the MnO2 with Bi. In this talk we detail using Bi doping for structural stabilization of MnO2 cathodes for Li-ion and Na-ion batteries in dry, non-aqueous electrolyte. We do this by preparing a series of Bi-doped layered MnO2 compounds, which also contain K ions and crystal water. These phyllomanganates or birnessite-type compounds have the general formula KxBiy-MnO2 • nH2O. The materials are structurally characterized by synchrotron X-ray powder diffraction (XPD) and confocal Raman microscopy. It is found that incorporation of Bi in the structure increases the crystallinity of the material by ordering the interlayer cations. This ordering results in the emergence of a structural superlattice in the material, which has been reported previously for birnessite inserted with other heavy, multivalent cations such as as Sr2+, Ba2+, and Ca2+.We selected three Bi doping levels to study in Li-ion and Na-ion batteries: undoped (y = 0), low-doping (y = 0.013 or 1.3%), and high doping (y = 0.043 or 4.3%). Both doped materials had capacity over 200 mAh/g and allowed for far more stable cell cycling than the undoped Kx-MnO2. The cells made with 4.3% doping of Bi were by far more stable. These cycled at 175-190 mAh/g specific capacity through 100 cycles with a nominal voltage of 2.9 V. Operando XRD experiments to characterize the cathodes within sealed coin cells showed that high-level doping (4.3%) promoted dehydration of the KxBiy-MnO2 interlayer, which had a distance of 6.4 Å. This showed that loss of the crystal water from the interlayer was key to achieving maximum stability during cycling. Lower Bi doping (1.3%) did not cause loss of the crystal water once the cathode was wetted with electrolyte. Previous reports have suggested that Bi doping of 20% results in stabilized Li-ion cycling in layered MnO2. However, these reports involved largely amorphous active material. Our results showed that Bi doping of only 1.3% still provided a large stability benefit, and the high crystallinity of our material allowed it to be structurally characterized, both in the as-prepared state and operando during battery cycling. Results from Na-ion cells will also be presented.Stabilized MnO2-based cathodes that cycle with good capacity and somewhat lower cell voltage than traditional Li-ion cells are a promising strategy for low-cost batteries for the grid. The possibility of using Na as the working ion is also useful for large-scale deployment of batteries to balance renewable power. Acknowledgments This work was supported by the U.S. Department of Energy (DOE) Office of Electricity Delivery and Energy Reliability, Dr. Imre Gyuk, Energy Storage Program Manager. This research used resources of the Advanced Photon Source beamline 6-BM, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research also used resources at beamlines 7-BM (QAS) and 28-ID-2 (XPD) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

Engineering Routes Towards Practical Sodium-Ion Batteries: Case Studies from Oxides to Polyanion Compounds

Benefiting from the substantial knowledge accumulated on lithium-ion batteries, tremendous progress rapidly occurred with focus on solving the fundamental issues encountered at the component, system and cost levels in sodium-ion batteries. Of particular interest, P2-type layered oxide, Na2/3Fe1/2Mn1/2O2, has been researched as a potential cathode in SIBs based on its high theoretical capacity of 260 mA h/g and use of noncritical materials. Firstly, we reported a novel synthesis route using low-temperature eutectic reaction to produce highly homogeneous, crystalline, and impurity-free P2-type Na2/3Fe1/2Mn1/2O2 materials. We further synthesized Na x NiyMn1-yO2 cathodes with the same eutectic method and investigated the gassing properties of pouch cells when being charged to higher voltages. Even with gained knowledge of how to engineer layered oxide cathodes, the compromised electrochemical performances and associated safety risks at high voltage still hinder their high-energy applications. In contrast, polyanion cathode stands out as a great candidate due to its high nominal voltage and stability in ambient environment. However, pristine Na3V2(PO4)3 often exhibits reversible capacities of around 100 mAh/g for long term cycling, which is still 20% below the theoretical values. To tackle this issue, transition metal (Fe, Mn, Ni) and fluorine ion were introduced as doping elements to improve the specific capacity and cycling stability of polyanion cathodes. Advanced characterization results provided insights in the charge compensation mechanism of these cathodes. Stable electrochemical performances were demonstrated in multiple cell configurations. It is thus believed that these polyanion cathodes are promising for the next generation practical sodium-ion batteries.

A glitch free variability resistant high speed and low power sense amplifier based flip flop for digital sequential circuits

In this work, a sense amplifier based flip flop (SAFF) is presented appropriate for high speed, high data activity and low power operations. The delay and power of the proposed flip flop have been considerably reduced as it uses a novel single-ended latch structure. The flip flop (FF) also achieves glitch free operation and can be operated and is functional at near-threshold voltage levels. SPICE simulations were carried out to do a comprehensive and quantifiable analysis between the presented architecture and formerly known architectures in 32 nm CMOS technology. The proposed design achieved a reduction of minimum 22.67% in power at nominal voltage. In terms of Power Delay Product (PDP), a reduction of 63.51% was observed. At 100 MHz clock frequency, the power dissipation was lowered by 30%. The proposed design at data activity of 100% consumes 28.24% less power whereas at activities of less than 12.5% it does not show significant improvements. However, the proposed design has an advantage in terms of speed and is 40% to 82% faster at nominal conditions and can also operate at wide supply voltage. It also has the second lowest transistor count and second lowest area. The power performance is verified by implementing the proposed design as a 4-bit shift register.

Modelling and Performance Analysis of a Tidal Current Turbine Connected to the Grid Using an Inductance (LCL) Filter

Nowadays, integrating renewable energy sources, such as tidal power, into the existing power grids of turbines is crucial for sustainable energy generation. However, tidal turbine energy transforms the potential energy of moving water into electrical energy. When both nonlinear load and dynamic load harmonics are present, the tide speed variance causes serious power quality issues such as low power factor, unstable voltage, harmonic distortions, frequency fluctuations, and voltage sags. The integration of an LCL-filter-based connection scheme can address these challenges by improving power quality and the overall performance of the tidal current turbine grid system. This study shifts LCL filter research from its conventional wind energy emphasis to the emerging field of tidal stream generation systems. The LCL filter analysed in this paper is modelled to exhibit adequate mechanical, electrical, and hydrodynamic characteristics. This model accounts for tidal current variations, turbine speed control, and power extraction dynamics. The LCL filter is evaluated for its effectiveness in reducing harmonic distortions, voltage fluctuations, and reactive power fluctuations. This system is composed of a 1.5 MW/C, a 1.2 MW three-level inverter with a nominal voltage of 600 V, and an inductance (LCL) filter. The results show that the inverter produces a harmonic distortion of less than 0.5%, which demonstrates the effectiveness of the filter in improving total harmonic distortion, reactive power consumption, and voltage control.

Large-signal time-domain equivalent circuit model for PEM fuel cell stacks

Hydrogen fuel cells have become one of the most viable power sources for electric aircraft. Models representing the electrical behavior of the fuel cell stack over the full dynamic operation region are essential for the development of power electronic energy systems powered by fuel cell stacks. This work presents an electrical equivalent circuit model for PEM fuel cell stacks representing the static and dynamic electrical behavior of the fuel cell stack under pulsed loads up to frequencies of 10 kHz. Dynamic phenomena on time scales slower than the considered timescale of power-electronic switching, such as reactant flow, membrane hydration, and temperature effects, are considered stationary. The parameterization method proposed is developed on measured data from a 110 W PEM fuel cell stack and validated with a set of measured data from a 2 kW stack. The time-domain simulated behavior of the parameterized model shows an accurate representation of the measured behavior: the parameterized model reproduces both the static polarization behavior and the behavior under high-frequency pulsed loading with errors of less than 1% with respect to the nominal stack voltage. The model is suitable for dynamic simulation of power electronic systems directly connected to fuel cell stacks and can be parameterized without special electrochemical impedance spectroscopy measurements.

An in-depth investigation into the influence of temperature on the electrochemical behavior of electric double-layer capacitors containing ethyl isopropyl sulfone-based electrolytes

The surrounding temperature significantly impacts the electrochemical behavior of electric double-layer capacitors during operation. While low temperatures restrict the transport properties of the charge carriers and lower the overall cell performance, higher temperatures improve the transport properties and performance but lead to the decomposition of the materials. To address this issue, the supercapacitor's nominal voltage must be lowered to ensure a long cycle life. With the aim of understanding the temperature-dependent behavior of supercapacitors based on ethyl isopropyl sulfone and acetonitrile, various electrochemical investigations at different temperatures up to 80 °C are presented. Interestingly, these investigations reveal a contradictory performance evolution over the temperature caused by the different solvents. Supported by the different stabilities of these two electrolytes, different optimal temperature ranges of application for electric double-layer capacitors based on these solvents can be concluded from these findings.

State of charge estimation and error analysis of lithium-ion batteries for electric vehicles using Kalman filter and deep neural network

The lithium-ion battery has a great significance in meeting the growing demand for Electric Vehicles (EVs) due to its higher energy density, longer life cycle, and notable nominal voltage and capacity. One crucial parameter for lithium-ion batteries is the State of Charge (SOC), which represents the available capacity and ensures that the system operates in a secure and reliable mode for EVs. SOC plays a significant role in the Battery Management System (BMS). This research aims to propose an Equivalent Circuit Model (ECM) based on Kalman filtering method and a data-driven technique, Deep Feed-Forward Neural Network (DFNN), for accurate SOC estimation of Electric Vehicle Battery (EVB). Initially, lithium-ion battery parameters are identified using a second-order RC (2-RC) Equivalent Circuit Model (ECM). Subsequently, battery modeling is performed, and various operating conditions such as terminal voltage, load current, and temperature are measured to obtain initial values for the filtering method used in SOC estimation. These operating conditions are crucial for ensuring safe and efficient charging and discharging of lithium-ion batteries. Based on the identified ECM parameters, SOC estimation error and bound error are then minimized using Kalman Filter (KF), Extended Kalman Filter (EKF), and Unscented Kalman Filter (UKF) techniques. These filtering methods are employed to accurately estimate the SOC of the battery. The results demonstrate that the proposed model based on KF and EKF algorithms estimates SOC bound error within 2.5 % - –2 % and estimation error <1.5 % - –0.7 %. On the other hand, the UKF estimates a SOC bound error of 1.5 % and an estimation error of 0.5 %, proving the algorithm's efficiency and reliability. Particularly, this estimation error rejects measurement noise and parametric uncertainties for lithium-ion batteries to drive EVs with efficacy using UKF. Hence, the UKF algorithm estimated SOC has low estimation error, ensuring more accurate results. Finally, data-driven, DFNN method is implemented for accuracy enhancement of SOC estimation with trained 20 iterations and epochs data. Using this method, the SOC estimation accuracy is satisfactory with only 0.04 % Root Mean Squared Error (RMSE). The validation results indicate that the model-based filtering method is an effective method for SOC estimation to be applicable. In contrast, in a novel data-driven approach, SOC estimation accuracy is improved by approximately 0.46 %.

Single-Event Upsets for Single-Port and Two-Port SRAM Cells at the 5-nm FinFET Technology

Single-event cross sections of single-port and two-port SRAM designs are presented at the 5-nm node for alpha particles, 14-MeV neutrons, thermal neutrons, and heavy ions for reduced and nominal supply voltages. Single-port SRAM shows higher susceptibility with low LET particles at nominal operating voltages. However, circuit and parasitic differences in designs lead to the two-port design having higher susceptibility to high LET particles. The stronger dependence of two-port SRAM on particle LET is due to the increased contribution of diffusion current to overall charge collection. The increased number of fins connected to a storage node for the two-port design significantly increases diffusion charge collection and SEU cross-section, despite increased critical-charge and cell size.

Modelling and analysis of electrical performance outdoor glass insulator under various services and lightning impulse

This paper is focus on modelling of glass type insulator with voltage rating of 275 kV. The glass insulators are still widely served in overhead transmission line because of its high dielectric strength capability. However, their outdoor application has resulted in the exposure to the various service conditions such as weather, pollution and lightning conditions. Further, the inclination effect of the insulator under the nominal voltage and lightning impulse is modelling through Finite Elementary Method (FEM). Then, the model of glass insulator is constructed in three different inclination angles by using the Ansys Maxwell 3D for simulation purpose. The results show the inclined insulator due to the wind load effect has the lowest breakdown voltage at most 53.33% compared with the vertical insulator. Under the outdoor environment factors such as humid, wet and contamination, the localized electric field and current density had increased significantly. Consequently, this situation may cause the power losses, localized heating effect also reduces the electrical performance of the insulators.

Analysis Of Modern Railway Power Quality Conditions With Inspection Methods To Mitigate Operating System Failures Referring To Regulations And Standard References

Elevated stations or commonly called elevated stations have an electric power system with a main power supply of 20KiloVolt with a nominal voltage of 750volt and a station operating facility voltage of 380volt laying station. This research uses the inspection method by making observations by work instructions and instruction manuals for railway infrastructure maintenance studies. Some were identified as related to power quality issues with progression-appropriate inspections and appropriate instruction manuals. The main objective of this study is to prevent overvoltage interference problems by recommending risk mitigation through investigative and simulation analysis methods using Electric Transient and Analysis Program (ETAP) software that can help evaluate and estimate strategic steps by paying attention to regulations and standard references and detecting losses in operating pattern disturbances due to disruption of power quality conditions caused by overvoltage surges in the station traction substation system by investigation and simulation methods using Electric Transient and Analysis Program (ETAP) software. This overvoltage is carried out in the context of research on maintaining services to the public and preventing system failures by using risk mitigation and investigation and simulation methods using Electric Transient and Analysis Program (ETAP) software that pays attention to environmental, safety, technical, and economic aspects with regulations and standard references. This research is in the form of mitigation analysis and describes the losses that have an impact by looking at a power quality condition and the follow-up provided to prevent overvoltage and components of modern railway electric facilities.

Automatic Excitation Control Using PI Method Based on Analysis Root Locus for Synchronous Generator

The demand for electrical energy is increasing (at 2–3 percent per year). It is necessary to utilize the energy available in nature optimally and stably to fulfill electricity needs. Synchronous generators have an essential role in fulfilling electricity needs. Maintaining and improving the operational stability of the synchronous generator is fundamental to the safe and economical operation of an electric power system. The use of control methods to increase control excitation is recognized as an economical and effective way. Previous research shows there are still areas for improvement in the excitation control method. Thus, this research focuses on optimizing the automatic excitation system using the PI control method with stability analysis using the root locus. The effect of PI control on the results of the characteristics response has Tr is 1.9 s, Ts is 6.6 s, Mp is 38.95 percent, and Ess is 11.02 percent. While the generator excitation current will increase in line with the increase in load current, and the resulting output voltage will be stable with errors that occur when compared to the nominal voltage is 10.51 percent because the sensor reading is affected by a frequency that is not following the operating frequency.DOI: 10.17977/um024v8i12023p036

Designing a Smart Inverter for Compensating the Voltage Sag Caused by Motor Start-up

Starting a large induction motor will always follow up with an inrush current as the nature of an induction motor. On a less stiff power system, that inrush current will be causing a Voltage Sag (VS). A big VS can lead to significant disruptions in power quality and reliability. To address this, a Smart Inverter with an Artificial Intelligence (AI) -driven controller installed in a Photovoltaic (PV) farm is proposed for voltage sag recovery. During normal conditions, the PV farm acts as a power source supporting the main grid, but when large induction motors are started, the smart inverter connected to the PV is responsible for power conversion to recover sags caused by the Induction motor inrush current. The controller inside the Inverter ensures optimal operation. The use of AI also compares the effectiveness of using the Fuzzy Logic Controller (FLC) with the Proportional Integral (PI) Controller to assess their performance in reducing current spikes. Based on simulations, the FLC outperformed PI Controller in mitigating the voltage sag and avoiding the Low Voltage Ride-Through (LVRT). Simulation results show that voltage sag can be recovered for up to 97% of the nominal voltage, a significant improvement over the 80% sag recovery without the smart Inverter. At a nominal grid voltage of 6,600 volts, the VS Magnitude was successfully increased from 5,210 volts to 6,368 volts and the VS Duration also decreased from 6.96 s to 4.97 s. The results achieved validate the effectiveness of the approach in improving the power quality.

Development of Current-Fed DAB Converter Applying Triangular Current Mode for Wide Voltage Applications

This paper proposes a control and modulation method for a Current-Fed Dual Active Bridge (DAB) converter to improve the conversion efficiency for wide voltage range applications. The current-fed DAB converter is preferred in battery applications owing to its high-power density and low current ripple. On the other hand, the high-conversion efficiency range is limited to close to the nominal DC voltage condition as the DAB converter. The proposed method provides Zero-Voltage-Switching (ZVS) in a wide DC voltage range by Triangular Current Mode (TCM). Furthermore, the proposed control reduces the inductor RMS current compared with the DAB converter to minimize the conduction loss. The validity of the proposed method is established by experimental results. According to the experiment using a 2-kW prototype, the conversion efficiency reached 97.2% when the input voltage was varied by 50% from the nominal DC voltage, then the conversion loss was reduced by 52.5% owing to the proposed control. Finally, the maximum power density of the current-fed DAB converter was improved by 38.1% compared to that of the DAB converter.

A New Active Front-End Control for Regenerative Cascaded H-Bridge Motor Drives With Filter- Less Interfacing Capability

This paper proposes a new active-front-end (AFE) control method for regenerative Cascaded H-bridge (CHB) motor drives. Conventional CHB converters have dominated the market for the medium-voltage industrial motor drives. However, conventional CHB converters cannot provide regenerative capability. To enable regeneration; diode-front-ends (DFEs) in power cells are replaced with IGBT-based PWM AFEs. Despite the appealing dynamic performance of PWM AFEs, their integration to the CHB converters is not optimal. First, they introduce more semiconductor losses due to the high frequency switching. Second, they introduce switching harmonics that are not cancelled by phase-shifting transformers. Therefore, they require additional harmonic filtering solutions to comply with grid harmonic standards. To resolve these challenges, this paper proposes a new AFE control for regenerative CHB converters based on fundamental frequency switching (FFE) to reduce switching frequency and thus power losses. The operation of FFEs at nominal and sag voltage conditions is presented, in addition to the capability of filter-less interfacing to the transformer. Finally, the performance of the proposed control is validated experimentally on a seven-level regenerative CHB drive.