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We developed the alarm fuse for High Voltage Direct Current (HVDC) power system. It was realized stable breaking characteristics and low transient voltage by our specific know-how for interrupting DC voltage and unique shape of fuse element.
Recently, a world is the point of need with new energy of high efficiency measures according to global climate change issues and energy shortages. [1] One of the various measures an energy control is to design and development at a precise circuit that can be used conservation and efficiency as the center with the power in industrial apparatus. High-frequency induction heat treatment industrial facilities...
In this paper, a nanosecond level response digital pulse width modulation (PFM) control circuit for the current resonant converter such as LLC has been proposed. The proposed circuit is composed of a unique analog to digital converter and logic based digital controller. With the experimental results, it was confirmed that the switching frequency can be varied from 0.8 to 1.2MHz in regard to 20% variation...
This paper proposes a method to improve the power efficiency in the half-bridge LLC resonant DC-DC converter. The optimum design of a transformer is discussed to improve power efficiency. The interlinkage magnetic flux in the primary and secondary wires causes eddy currents, which results in a power loss. This study demonstrates that power loss can be reduced through optimum design of the strand diameter...
This paper presents the parameter design of the integral gain switchover function for the digital control dc-dc converter and its transient response in the DCM. The proposed gain switchover function utilizes the load current to determine the integral gain because the output current is detected in the dc-dc converters for the ICT system. The proposed method uses the hysteresis function around the critical...
This paper proposes a dc power supply system to give high power factor and low current distortion on the rectifier side and provide stable dc voltage on the isolated dc/dc converter side. The proposed dc power supply system uses a new ZCS strategy to get ZCS function. Besides operating at constant frequency, all semiconductor devices operate at ZCS without additional current stress. A significant...
This paper focuses on the circuit which is to reduce the number of switching elements in comparison to a common multi-level inverter NPC inverter. Increasing the number of levels of the output voltage at reduced circuit number switching elements, and performs waveform improvement. Typically, the ratio of the input voltage of the multi-level inverter is E1 : E2 = 1 : 1. When the ratio of the input...
This paper investigates the design and validation of a new space vector pulse width modulation (SVPWM) algorithm for thermal protection of T-type three-level inverters. Thermal overheating is the main cause of shortened-lifetime and open-circuit faults of power devices. Power devices are subjected to thermal overheating due to degradation of power devices due to continuous overloading and power cycling,...
This paper proposes a power-loss reduction technique for a kW-scale isolated dc-dc converter, which installs a novel PWM control to achieve the soft-switching of primary side MOS-FETs. As a result, the efficiency is achieved over 90% in a wide load range. Moreover, the temperature of the primary side MOS-FETs can be reduced by 30 degrees when compared with the conventional method, and the power-density...
Renewable energy system such as a photovoltaic, a wind turbine generation and fuel cell has attracted attention as alternative energy sources of fossil fuel. However, a distributed generating system with the photovoltaic or the wind turbine generation is difficult to obtain a constant power supply. Thus control of power leveling system is required to maintain the balance of power flow for irregular...
Recently, the Electric vehicles (EV) became more popular. The construction of the EV charging stations is important in order to satisfy the energy demand of large quantity of electric vehicles. This paper presents design and simulation of EV charging station using three-level converter in the grid-side as well as in the EV-side. The charging station architecture with an AC/DC conversion and DC/DC...
By constructing a small-scale microgrid, we have examined a control and operation method for the efficient use of distributed power generation. Thus far, the high-efficiency operation of distributed power introduced into grid has not been achieved. In this study, a method that operates a microgrid by predicting the PV output and electric power demand is proposed. Then, the effectiveness of this method...
This paper presents the electric vehicle(EV) system using module balancing method in vehicle-to-grid(V2G) system. Since there are intrinsic discrepancies among batteries, the state of charge(SOC) of each battery after charging or discharging may not be the same. Consequently, the batteries are with different voltages during the charging and discharging process. As a result, over-charging or over-discharging...
We present an integrated approach for allowing a commercial building to reduce the peak demand of electrical power by air conditioning control, while maintaining comfort. The proposed method controls simultaneously, the power demand and room temperature change in the building. Power demand forecast is used to forecast the time of peak demand for the building. Heat capacity modeling is used to estimate...
A family of four quadrant DC/DC converters is presented in this paper. Compare with existing four quadrant DC/DC converters that have been introduced in literature, the proposed converters have lower number of components. There are two bidirectional switches, two coupled inductors and one capacitor in proposed converters that can lead to lower cost and also smaller occupied space. The proposed converters...
As energy storage finds its way into everyday life around the world, focus on design for safety is imperative for battery technology to be adopted worldwide. Energy storage, especially as applied in telecom systems, must be properly managed independent of energy storage technology or battery chemistry. The paper will start with the roles of a simple battery management system and then scale up to the...
With the recent focus on DC power distribution in the built environment due to ease of integration of DC energy sources such as solar photovoltaic and battery energy storage, the Extra Low Voltage DC (ELVDC) power distribution system suitable for high rise building with direct integrated DC energy sources and LED lighting loads is discussed in this paper. Design considerations and system level modeling...
The purpose of this paper is to propose a new control method of wireless power transfer system that can maintain stable power supply even when the positions of the primary and secondary coil or distance between the two coils largely change. The new method will be done by adjusting the switching frequency to a frequency that can obtain the desired output. We confirmed the effectiveness of new wireless...
Capacitive power transfer uses an electric field to transmit power through physical isolation barrier utilizing capacitances formed by a couple of metal plates. Despite simplicity of the energy link structure, however, the physical dimension and low dielectric constant of the interface medium usually limits the effective link capacitance to be very small and nearly comparable to the main switch output...
Based on a modular design concept, 100 kVA uninterruptible power system using double-sided air-cooled power module has been developed. An efficient air-cooling system suitable for the double-sided cooled power module is developed, and the volume of the converter adopted developed double-sided air-cooling system becomes less than half compared to the conventional converter based on single-sided cooling...
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