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This paper studies the dynamics of the proposed vibration energy harvester to develop the method of designs and controls for the system. The harvester converts vibrational energy into electrical energy through rotational motion of a mechanical pendulum or a so-called parametric pendulum. The rotation is maintained for periodic vibration with appropriate amplitude and frequency. However, such appropriate...
Active damping of grid-connected LCL filter resonance by means of an observer loop to estimate the capacitor current is a well-known method. However, with variation of the grid side inductance due to grid conditions, the system robustness has to be checked. This work discusses the effect of the observer design on the system robustness against grid side inductance variation. Different values of resonant...
In view of the emerging demand for longer-term industrial or second life of lithium-ion batteries, aging effect(s) should be seriously considered to understand all potential safety risks behind those applications. In this study, four categories of critical aging effect(s), including degradation of construction integrity, self-heating effect, decay of thermal stability and failure in key components,...
Three phase PFC rectifier followed by a DC-DC isolated converter has been the industry workhorse for conversion of three phase AC to isolated DC output used for high power (> 3kW) telecom loads. In this paper a reduced device count nine-switch converter topology which integrates the two stages of a conventional three phase AC-DC power supply with an isolated DC output voltage for telecom applications...
This paper presents a quantitative framework for measuring and characterizing resilience of information and communications technology facilities with a focus on their power supply. Although the focus of the presented framework is for communication networks power supply, it is also applicable to power grids in general. The proposed framework uses a measure analogous to availability in order to measure...
The main theme of this paper is to propose a switching control method for LLC converter with larger magnetizing inductance to improve the light load efficiency. The proposed switching technique is to replace conventional frequency modulation method which is with constant duty while regulating the output voltage by varying the switching frequency, with pulse-width modulation while retaining the special...
The subsidy feed in tariff policy, which has been adopted in the past few years, for accelerating renewable energy investments, cannot be retained as a sustainable business model for the future smart energy grid. This is mainly due to the fact that this policy increases the energy cost, especially when the amount of the energy generated by renewable sources is not negligible compared to the traditional...
In this paper, power losses of 3-level NPC inverter (3LNPCI) and 3-level T-type inverter (3LTI) are classified and calculated according to the switching states. The conduction loss depends on modulation index (MI) and power factor (PF), whereas the switching loss depends on switching frequency, so the power loss analyses have been done at the different operating points of MI, PF, and switching frequency...
When a emergency occurs in the solar power generating, to confirm that there is a possibility of arcing. As long as there is solar radiation, solar power generation keeps supplying the electric power. Therefore if the arc occurs, there is a risk of fire. However, protection device for protecting a direct current system side was not present. We have developed a protective device for performing emergency...
A primary-side regulation AC-DC converter operating in PFM (Pulse frequency modulation) mode with highly accurate output current is designed, which employs a novel inductance compensation technique to improve the precision of output current, diminishing the bad impact of the big tolerance of the transformer primary inductance in the same batch. An improved method to detect the demagnetization time...
Highly efficient multi-cell rectifier using low-voltage GaN transistors has been proposed for future 380-V dc distribution in data centers. A 98.8% full-bridge 33- to 48-V ac-dc cell converter has been developed by using GaN transistors. This cell converter maximizes the performance of the multi-cell rectifier based on the series-parallel connection topology of isolated power converters. The potential...
In recent years, there is growing interest in improving lithium-ion battery state monitoring. This is due to growing concern over ensuring reliable and safe operation of lithium-ion based energy storage system especially in automotive and stationary e.g. UPS in data center applications. In this paper, battery state of charge estimation based on Extended Kalman Filter (EKF) and improved battery model...
A battery management system (BMS) is a system that manages a rechargeable battery (cell or battery pack), by protecting the battery to operate beyond its safe limits and monitoring its state of charge (SoC) & state of health (SoH). BMS has been the essential integral part of hybrid electrical vehicles (HEVs) & electrical vehicles (EVs). BMS provides safety to the system and user with run time...
This paper proposes a design method of a common-mode current feedback type EMC filter in an interconnection system. First, the relationship between the switching frequency of the PWM inverter, the common-mode feedback current and the volume of the filter reactor is theoretically estimated. Moreover, the switching frequency and the current capacity of switching devices which are necessary in order...
BTS sites are subject to constant cost pressure. Operational cost and especially Diesel consumption form ever increasing cost components. Here, photovoltaics (PV) is an effective measure to cut down operational cost and emissions for hybrid BTS sites. Often PV is integrated in a non-optimal way opening up room for improvements to the operational management. Three different advanced PV-hybrid operational...
This paper introduces a highly-efficient two-stage DC-DC converter with wide input voltage. Based on the digital control technology, it uses two-stage DC-DC conversion. This paper describes the circuit topology, working principle and control method of the convert in detail. The converter consists of the former input circuit, intermediate conversion circuit, output rectifying circuit and feedback control...
More effective electrical energy production requires more attentions to storage technologies. This paper analysis and compares different electrochemical energy storage technologies, in the terms of energy/power density, specific energy/power, efficiency, lifespan, cycle life, capital energy/power costs, scale, application, technical maturity, as well as environmental impacts. The pioneering countries...
For IT data center and high voltage UPS applications, selecting a lithium-ion (Li-ion) backup solution for a critical standby power source can help users to benefit from a reduced installed footprint, optimized total facility energy and a reduced environmental footprint when compared to conventional battery solutions. Backup systems utilizing high power Li-ion cells offer the ability to significantly...
A current sharing method considering battery state of charge(SOC) for multi-module uninterruptable power supply(UPS) system is proposed. Modularized UPS system consists of a single master module and multi slave modules. A master module performs output voltage control and distributes current commands to slave modules. The current commands are generated by using the proposed current sharing algorithm...
This paper proposes a current-fed two inductor bi-directional DC-DC converter using resonance (CF-TIBCR). The power losses of CF-TIBCR mainly occur in switches, especially the low voltage side switches. To improve the efficiency, the detailed loss analysis of switch and magnetic components is performed from the steady state analysis and operation principles. To verify theoretical loss analysis, it...
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