Soon-Ryung Lee

Battery Balancing Algorithm for Parallel Operation of Single Phase UPS Inverters

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.

Flyback Inverter Using Voltage Sensorless MPPT for Photovoltaic AC Modules

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.

Economic dispatch algorithm considering battery degradation characteristic of energy storage system with PV system

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.

An Optimal Method to Design a Trap-CL Filter for a PV AC-Module Based on Flyback Inverter

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.

Battery balancing algorithm for serial multi-module UPS system

In this paper, battery balancing algorithm for serial multi-module UPS system is proposed. The battery balancing algorithm is performed by the output power control of each UPS modules for eliminating SOC difference of batteries respectively. So, the coulomb counting method is used to estimate SOC of the batteries. The reference is compensated with SOC difference and according to magnitude order of SOC . Finally, the output voltage becomes sum of output voltage of UPS modules and the utilization of the battery is increased in serial UPS system. The validity of proposed battery balancing algorithm is verified by simulation results.

Personal Cognitive Characteristics in Affordance Perception: The User Activity Case Study in a Building Lobby

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

A novel phase shedding control algorithm considering maximum efficiency for 3-phase interleaved boost converter

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.

The predictive control of single-phase UPS system for fast dynamic characteristic

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.

Current sharing algorithm for parallel operation of single phase UPS inverters using predictive current control

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.

ESS operation algorithm for economics considering battery degradation properties

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.