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This paper proposes a novel dual integrated LLC resonant converter (DI-LRC) with a wide output voltage range using various switching patterns. The primary side of the proposed DI-LLC converter consists of two resonant tanks and six switches, while the secondary side consists of a six-pulse diode rectifier. Depending on the switching pattern of the primary switch, the DI-LRC converter is performed by single full-bridge operation with a voltage gain of 1, series-connected full-bridge operation with a voltage gain of 0.5, series-connected half bridge operation with a voltage gain of 0.25, and parallel-connected full-bridge operation with a voltage gain of 2. Accordingly, the proposed DI-LRC converter has four voltage gain curves with different variations and achieves a wider output voltage range than the conventional single voltage gain curve in a given operating frequency range. In this paper, the equivalent circuits derived for each switching pattern are proposed to analyze the operating characteristics of the proposed converter according to each switching pattern, and each Q factor and voltage gain are calculated based on the analyzed equivalent circuit. The performance of the proposed converter and switching pattern is verified using the simulation and experimental results of the prototype battery charger, which is designed to be 4-kW class.

Recently, Uninterruptible power supply(UPS) is spotlighted from concern about black out, due to reserve power problem caused by increased power consumption. When fault occurs on the grid, UPS system supplies power to loads instead of the grid. Also, it is an advantage of possible operation as Energy storage system(ESS). Bi-directional power control of AC/DC Pulse width modulation(PWM) converter is essential for grid-connected UPS system. And, mode transfer control has to be performed considering phase and dynamic characteristic under grid condition. In this paper, control of mode transfer and bi-directional power control of AC/DC PWM converter is proposed for UPS system. Also, it is verified by simulation and experimental results.

A flyback inverter using voltage sensorless maximum power point tracking (MPPT) for photovoltaic (PV) AC modules is presented. PV AC modules for a power rating from 150 W to 300 W are generally required for their small size and low price because of the installation on the back side of PV modules. In the conventional MPPT technique for PV AC modules, sensors for detecting PV voltage and PV current are required to calculate the PV output power. However, system size and cost increase when the voltage sensor and current sensor are used because of the addition of the auxiliary circuit for the sensors. The proposed method uses only the current sensor to track the MPP point. Therefore, the proposed control method overcomes drawbacks of the conventional control method. Theoretical analysis, simulation, and experiment are performed to verify the proposed control method.

In this paper, ZVT interleaved bidirectional LDC(IB-LDC) with switching frequency modulation for mild-hybrid electric vehicle is proposed. The IB-LDC is composed of interleaved buck and boost converters employing an auxiliary inductor and auxiliary capacitors to achieve zero-voltage-transition. Operating principle of IB-LDC according to operation mode is introduced and mathematically analyzed. Moreover, switching frequency modulation control is proposed to reduce circulating current for low power range. Furthermore, a 600W prototype of ZVT IB-LDC for MHEVs is built and tested to verify validity.

This paper presents a ZVT(zero-voltage-transition) interleaved synchronous buck converter with passive soft-switching cell to achieve ZVS(zero-voltage-switching) of MOSFET switches. The proposed interleaved buck converter is composed of two synchronous buck converter modules and passive soft-switching cell. The passive soft-switching cell consists of coupled-inductor and DC-link capacitor. All switches operate with ZVS by the current of auxiliary coupled-inductor. Comparing the conventional interleaved buck converter, the proposed interleaved buck converter reduces the switching loss and increases the efficiency by using only passive components. In this paper, mode analysis and design consideration is described in detail for operating the ZVS. The proposed ZVT interleaved synchronous buck converter is verified with experimental results.

A novel phase shedding control algorithm considering maximum efficiency for 3-phase interleaved boost converter is proposed. The phase shedding control algorithm is performed to control the operating phase of interleaved converter in accordance with wide load range for high efficiency. Conventional interleaved converter has low efficiency under the light-load condition. In this paper, the 3-phase interleaved boost converter has wide load range by the phase shedding algorithm to the interleaved converter, the validity of proposed phase control algorithm considering efficiency for 3-phase interleaved boost converter is verified by simulation results.

This paper presents design method of soft switching interleaved buck and boost converter for vehicle application. The soft switching interleaved buck and boost converter is composed of interleaved boost converter and resonant tank. The converter improve the problem of switching loss by employing the small size resonant tank compared with conventional interleaved buck and boost converter. The conditions of ZCS and ZVS of the converter are mathematically analyzed by using the mode analysis. Through the mode analysis, size of the resonant tank is optimized according to the rated power of converter. The design method is verified by simulation result.

Voltage limitation control considering battery module balancing for series connection UPS module system is proposed. The UPS modules system is consists of single master module and multi slave modules. The voltage limitation control is performed to balance the battery modules of UPS system. Firstly, the master module checks the SOC of UPS modules to make order according to SOC. And, the master module calculates points to limit output voltage to control output power of the modules. Finally, the output voltage becomes sum of output voltage of UPS modules because of the series connection. As a result, the utilization of the battery can be increased in series connection UPS system. The validity of proposed voltage limitation control considering battery modules balancing is verified by simulation results.

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 to balance the SOC of each UPS module. Moreover, the UPS mode transfer time can be significantly reduced by using the predictive current control. The predictive current control method is mathematically verified by analyzing the UPS system. The validity of proposed balancing method and predictive control is verified by simulation results.

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 low, output power of each module is controlled proportionally to equalize SOC of the battery modules. And the reference of the output powers is compensated according to magnitude of SOC difference. Eventually, utilization of the batteries can be increased by preventing over-charge and over-discharge problem. The proposed control is verified by simulation and experimental result.

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 UPS system, it is possible to decrease the transient time to load voltage when UPS system conducts mode transfer. In this paper, reference output current of load is calculated by formulating inductor current and capacitor voltage to apply the predictive control of single-phase UPS system. To verify validity of the proposed predictive control method, simulation and experiment are carried out based on 350W single off-line UPS system.

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 case, if the PV power is drastically changed, large capacitance as much as the whole PV system is required to reduce the DC-link fluctuation. Therefore, the DC-link voltage compensation method is applied to the DC-link control to reduce the DC-link voltage variation without using huge capacitor bank. The proposed control method is mathematically analyzed and verified by simulation results.

In this paper, energy storage system(ESS) operation algorithm for economics considering battery degradation properties is proposed. Hourly electricity charge according to real-time pricing (RTP) and battery properties are analyzed for high profit through ESS operation. Especially, hourly electricity charge of Illinois State is analyzed. Characteristics of battery accounts for a high percentage of ESS configuration. Thus, degradation properties of the battery for the price considering the loss of battery usage is considered. The algorithm is proposed for the highest profit through analysis of the battery degradation properties and electricity charge, and the proposed algorithm is verified by mathematical analysis.

In the photovoltaic (PV) AC-module system, the system size and weight are important design factors because AC-modules are installed to each PV panels. Since the most of harmonics occur at multiples of switching frequency, the harmonic elimination at switching frequency can be an effective technique for reducing the total filter size. To decrease output filter size, proposed output filter consists of trap filter to eliminate switching frequency harmonic and CL filter. In this paper, the trap-CL filter is analyzed, and its optimal design method is proposed. The validity of proposed filter and design method are verified by simulation and experimental results.

A current sharing method considering battery state of charge(SOC) for single phase uninterruptable power supply(UPS) module is proposed. Each of UPS module system is consists of single master and multi slave modules. A master module performs output voltage control and current sharing algorithm considering the battery SOC of each of the UPS modules. In current sharing algorithm, current commands are generated for eliminating SOC difference of batteries of each modules. However, the slave modules control the only output current which is generated by master module. As the output load current is shared by battery SOC of UPS module, the utilization of the battery is increased in parallel UPS system. The validity of proposed method is verified by simulation results.

In this paper, a control method for phase synchronous of each converter in photovoltaic (PV) hybrid module system (HMS) is proposed. A PV-HMS consists of a central inverter operated with a grid-line frequency and modularized converters installed backside of each PV module. In PV-HMS, the modularized converters has to operate with current-source converter using grid-line phase information because the central inverter is an unfolding bridge inverter which of switching frequency is equal to the grid-line. However, each modularized converter cannot get the grid-line phase information because these converters directly is not connected the grid-line. Therefore, this paper is proposed the control method for operation of each modularized converter through phase-lock-loop (PLL) DC-link voltage. The theoretical analysis of the proposed control method is verified by simulation results.

User activities in performing tasks are influenced by the way the user perceives the related surrounding context and environment and determined with user judgment preferences. Physical environment structures afford user activities when these are perceived. Thus, this paper addresses how user activities and perceived affordances are different reflecting personal creativity modes, which are determined by factual-intuitive perception inclination and subjective-objective decision preferences as well as introverted-extroverted nature. To design-in various affordance features for diverse users in varying contexts, understanding on relations between user personal characteristics and affordance perception would be helpful. We conducted a case study in a public space — building lobby — used by many general people. User activities and behaviors were analyzed in several specific tasks given to twenty students in the lobby of a building they have never been to before. The tasks were devised so that various affordance features could be relevant while eliminating other factors affecting the affordance perception than those due to user personal characteristics. User activities can be classified into several different groups for each task based on affordance features involved in their activities. These user activity differences are then compared with their personal creativity modes. For user of less common activities for some tasks, relevant personal cognitive characteristics have been identified.Copyright © 2008 by ASME

The power factor and total harmonic distortion (THD) are important considerations when designing an output filter. In the case of the photovoltaic (PV) ac-module, the size and weight also have to be taken into consideration. This paper proposes an output filter to reduce size and weight, and provides the optimal design method for a PV ac-module. The proposed output filter consists mainly of a conventional CL filter with a trap filter. The trap filter is used to eliminate the harmonic at the switching frequency that contains most of the harmonics. Therefore, total inductance and the size of the filter can be reduced although the output filter components are increased. This paper presents analysis of the proposed filter characteristics in detail. Also, an optimal design method reducing the size of the output filter components including the damping resistor is proposed. The proposed methods are verified on the experimental prototype rated at 320 W with an ac-module based on the interleaved flyback inverter. The total filter inductance and volume are, respectively, reduced to 9.54% and 26.62% with the same performance.