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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...
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...
In this paper, serial multi-module UPS system control considering battery module balancing is proposed. Because of the organization, the UPS system has some properties. One of them is output voltage is sum of each UPS module output voltage. Thus, each UPS module output voltage respective control can accomplish each battery module balancing according to SOCs of each battery module. As SOC is high or...
In this paper proposed highly efficiency PSU(Power Supply Unit) for server power supply. To minimize power conversion loss, PFC(Power Factor Collection) circuit was designed into Bridgeless PFC using two switching components with 2 SiC diodes, and synchronous rectifier switching method was applied. An isolated DC/DC converter used LLC SRC(Series Resonance Converter) to increase power efficiency and...
The current-fed two-inductor boost converter (CF-TIBC) has previously been demonstrated to have advantages in operating low voltage and high current input applications. Such characteristics are suited for photovoltaic (PV) or battery application, likes energy storage system (ESS) or electric vehicle (EV). In this paper, the current-fed two-inductor bi-directional DC/DC converter (CF-TIBDC) is proposed...
In this paper, feedforward compensation method is proposed to increase transient state dynamic characteristic of DC distribution system. In AC distribution system, voltage fluctuation of ±10[%] is regulated to normal range. Generally, the loads in AC system is not sensitive to voltage fluctuation because it supply power through DC/DC converter and diode rectifier. But, the loads in DC distribution...
In the electric vehicle(EV) system, the Technology for the efficient operation of a battery is one of the most important technologies. By the voltage difference between the cell and between modules of electric car battery, it will not be able to efficiently use the battery. Using the voltage balancing method to each of the battery modules to increase the available space for the battery module, it...
This paper proposes current-fed two-inductor bi-directional DC-DC converter using resonance(CF_TIBCR) for high efficiency and high step-up applications. Conventional dual half bridge(DHB) converter have problems of high voltage spikes and unavailable charge/discharge resulting from uni-directional converter. Hence, operating frequency and the efficiency are also limited. To solve these problems and...
Among researches in the use renewable energy resources, the study is actively in progress about micro-grid system applied DC distribution. Wind and photovoltaic (PV) sources which used at micro-grid as distributed power have flexible generation. When comparing with flexible generation curve and demand load curve, the produced power of micro-grid has deficient or excess case. So, Only pure generation...
This paper propose Zero Dead-time PWM method in 3-Level NPC(Neutral Point Clamped) inverter. Each switch of conventional PWM method is performs to complementary switching and semiconductor switch devices have time difference between rising time and falling time. Therefore, dead-time is applied to rising edge of switching signal for prevent short circuit fault. But this dead-time cause distortion of...
Recently, the mass production of Energy storage system (ESS) is actively perform around world. Energy storage system is a technique that stores power to energy storage device to supply energy into grid and load at peak-load. Therefore, the efficient energy management is available by using ESS system. The life of Lithium-ion battery is varied corresponding to the power usage, especially selected depth...
This paper proposes the modular low voltage DC/DC converters (MLDCs) in order to achieve state-of-charge (SOC) balancing of modularized batteries without additional balancing circuits. The MLDCs are substituted with the low voltage converter for EV, PHEV, and HEV located between the high-voltage side battery and low side battery. The MLDCs are composed of a number of modularized buck-converters and...
In Electric Vehicle (EV) application, a torque reference of IPMSM (Interior Permanent Magnet Synchronous Motor) depends on accelerator operation. As a torque reference changes instantaneously, IPMSM drive system requires fast current response to track a torque reference. General PI control which is used in industrial application causes time delay in transient state. To improve the performance of control,...
This paper proposes a phase current compensation method for a 3-Level NPC Dual Battery Pack charge/ discharge system. In this system, a DC link imbalance could cause distortion in the space vector diagram, which would cause distortion in the NPC phase current. The proposed compensation method eliminates this distortion. In this paper, the compensation method is proposed and verified by simulation.
This paper presents the predictive control of single-phase UPS system for fast dynamic characteristic. When occurring grid fault, UPS system has to transfer UPS mode and supply power to the load. In PI controller, it has a disadvantage rather low dynamic characteristic, which is caused increasing transient time. To solve this problem, the predictive control is proposed. By adopting predictive control...
In this paper, electric vehicle (EV) system using bi-directional DC-DC converter which can control the type of low-voltage and high-current battery is proposed. Proposed system uses isolated DC-DC converter for voltage compensation. The proposed topology has a form in which the inputs are connected in parallel and the outputs are connected in series in battery and isolated converters. The basic concept...
This paper proposes Voltage-doubler Rectifier type Full-bridge converter for bipolar LVDC distribution system. This converter is possible of bi-directional power flow and perform DC_link voltage balancing operation. System of bipolar structure has neutral-point unlike unipolar structure. But, this neutral point is incur DC_Link voltage unbalance between top and bottom capacitor. Thus, bipolar structure...
A DC-link voltage compensation method for a photovoltaic (PV) generation system with energy storage system(ESS) is presented. When PV power is oscillated, the DC-link voltage is also influenced. And this fluctuation of DC-link critically affects the load voltage when the ESS is operated in stand alone mode. In conventional method, huge capacitor bank is necessary to reduce the fluctuation. In this...
This paper proposes control method of Differential Discharge Handling (DDH) modules with state of charge(SOC) balancing between battery modules in Electric Vehicle (EV) system. The DDH modules are composed of battery modules and converter modules. To achieve high efficiency, the diode is replaced by MOSFET to use the synchronous boost converter. In order to reduce the ripple of input/output voltage...
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