Jin-Wook Kang

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.

Advanced control method of 3-phase AC/DC PWM converter for DC distribution using the SOGI-FLL

In this paper, control method which detects positive-sequence voltage and phase angle is proposed for dc distribution system. Apart from positive-sequence voltage extraction using phase delay of APF, conventional control method needs phase angle detection using the PLL. On the other hand, control method applied in proposed system is able to perform phase angle detection, positive-sequence voltage extraction and harmonic filtering only using SOGI-FLL. Validity of control method using SOGI-FLL is verified by PSIM simulation and experimental results.

Model predictive control of 3-level NPC AC/DC PWM converter for DC distribution using LCL filter

In this paper, model predictive control method is applied to improve output DC voltage dynamic characteristic of 3-level NPC AC/DC PWM converter for DC distribution using LCL filter. Generally, DC grid is applied to micro grid with renewable energy as photovoltaic, ESS. Renewable energy as photovoltaic causes transient state of DC bus voltage because input/output of energy is irregular due to irregular generating power of renewable energy. Transient state of DC bus voltage is required to be minimized for stable power supplying because most loads connected to DC grid require digital load which is sensitive to voltage fluctuation. Proposed control method improved transient state of DC bus voltage characteristic applying model predictive control AC/DC PWM converter for DC distribution using LCL filter. Proposed method is verified by simulation.

The Parallel Operation of Each other three phase AC/DC Converter using DC Current Droop Control for Multi-parallel DC Distribution System

DC distribution system is difficult to compose the single-system because of the capacity restriction of power semiconductors. Therefore, DC Distribution system needs parallel operation of AC/DC converters for increase to system capacity. However, this system generates the circulating current. This paper is reducing the circulating current and safely sharing the load using the proposed DC current droop control method when each other 3-phase AC/DC converter connected. This system confirms through the simulation and experiment. Also, when each other converter of parallel operate. it is compared the response characteristics

Automatic frequency tuning method of ozone power supply to optimize ozone generation system

In this paper, ozone power supply which consists of single-phase inverter, high-voltage step-up transformer, resonant reactor is presented. Also equivalent circuit which simulates the real discharge tube is presented. And PWM (Pulse Width Modulation) control method mixed with PDM (Pulse Density Modulation) control method is proposed for controlling the discharge power. Proposed autotuning freqeuncy method is compared with conventional autotuning frequency method. Resonant freqeuncy is selected by applying the proposed search method of resonance point. According to this method, method of obtaining the maximum voltage and power is proposed by adjusting the PDM. Proposed automatic frequency tuning method is verified by simulation and experimental results.