Seong-Chon Choi

LiFePO4 dynamic battery modeling for battery simulator

This paper proposes dynamic battery modeling for LiFePO4 battery simulator. LiFePO4 battery of Li-ion type battery has best characteristic in other type of batteries. So this paper describes LiFePO4 battery model for battery simulator. LiFePO4 batterys voltage waveform is non-linear and changed by transient load. So the shepherd model is applied to describe this non-linear waveform and thevenin battery model is applied to present characteristics of behavior corresponding to the changing of transient load. Also, in order to apply battery model to battery simulator, proposed battery model is converted to discrete time model. Parameters of proposed battery model are estimated in experimental. The proposed battery model is compared getting the voltage waveforms of the battery using experiment with simulations waveforms is verified.

A soft switching boost converter using an auxiliary resonant circuit for a PV system

This paper proposes a soft switching boost converter using an auxiliary resonant circuit for a PV system. The topology is composed of a general boost converter adding an auxiliary resonant circuit which has a switch, inductor, capacitors and diode. The auxiliary resonant circuit helps the main switch operate with ZCS and ZVS. And the auxiliary switch also operates with ZVS. ZVS and ZCS techniques enable to reduce switching losses and improve the efficiency of the system. The theoretical analysis is verified through simulations and experiments. The perturbation and observation algorithm is applied for this system. Experimental results are obtained from the 1kW prototype. Efficiencies by the variable duty and load are measured through the experiment.

A study on gantry crane control using neural network two degree of PID controller

During the operation of a crane system in the container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. An automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances and weight change. In this paper, we present the neural network two degrees of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control. Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

A residential 10kWh lithium-polymer battery energy storage system

This paper proposes a residential 10kWh lithium-polymer battery energy storage system. Considering a daily load profile, PV generation characteristic and battery SOC(State of Charge), operation modes are divided and algorithm is proposed. Concepts are to charge the battery during the night and to use the energy charged into the battery during the day time. A boost converter is used for maximum power point tracking(MPPT) and a perturbation and observation algorithm is applied to control MPPT in this paper. A bi-directional dc-dc converter is used to charge or discharge the battery and a constant current control is used for charging method. A bi-directional inverter performs the synchronization between dc power and ac power. Operation modes are verified through simulation.

Versatile power transfer strategies of PV-battery hybrid system for residential use with energy management system

This paper presents versatile power transfer strategies (PTS) of the grid-connected hybrid system based on energy management system (EMS). The hybrid system is composed of power conditioning system (PCS) for photovoltaic (PV), energy storage system (ESS) and battery management system (BMS). To effectively operate the grid-connected PV-battery hybrid system, it is necessary to operate the system with command of EMS considering various conditions through communication between EMS and hybrid system. The proposed PTS can be applied to EMS, taking into account the output fluctuation of renewable energy, load demand, state of the grid, peak load period and state of charge (SOC) for battery to effectively operate the grid-connected hybrid system. The high reliability and economic efficiency of system is achieved by applying the proposed PTS to hybrid system through EMS. The experimental results were presented to verify the proposed operation.

State-of-Charge Balancing Control of a Battery Power Module for a Modularized Battery for Electric Vehicle

This paper proposes a State-of-Charge (SOC) balancing control of Battery Power Modules (BPMs) for a modularized battery for Electric Vehicles (EVs) without additional balancing circuits. The BPMs are substituted with the single converter in EVs located between the battery and the inverter. The BPM is composed of a two-phase interleaved boost converter with battery modules. The discharge current of each battery module can be controlled individually by using the BPM to achieve a balanced state as well as increased utilization of the battery capacity. Also, an SOC balancing method is proposed to reduce the equalization time, which satisfies the regulation of a constant DC-link voltage and a demand of the output power. The proposed system and the SOC balancing method are verified through simulation and experiment.

The improved predictive current control for shunt active power filter with enhanced performance

In this paper, the improved predictive current control for shunt active power filter(SAPF) is proposed. To reduce the overshoot phenomenon of the input current caused by the delay element, the current predictive control is applied. But, the conventional predictive current control includes the problem that reduces harmonic removal performance and dynamic performance because it generates reference current when nonlinear load current is changed. In this paper, the above problem is solved by applying detection of increase of rotating reference d-axis of nonlinear load current. The proposed method is validated by simulation.

Control of multi-functional rapid charger for electric vehicle

This study deals with the rapid charger which is the mid-type between the slow and fast chargers in the aspect of charging time. In its functions, it can perform the Active Power Filter(APF) function without changing the topology besides the charging function. APF function is performed in accordance with the battery and charger of the electric car or checking the real time State of Charge(SOC) information of the battery obtained by Battery Management System(BMS). In addition, to perform the charging and APF functions, this paper proposes the driving mode selection algorithm. Based on the proposed mode selection algorithm, if it performs the APF mode, it can compensate the harmonic of the system and improve the using rate of each charger effectively except the ones performing the charging mode among the chargers located in a line. The operation of the charger that has the active power filter and the mode selection algorithm of this study are verified by the simulation and experiment test.

A high voltage battery simulator using Z-source converter with a wide output voltage range

This paper proposes the battery simulator using Z-source converter with wide output voltage range and we make a research on a control method for driving a battery simulator. We also explain the superiority in applying the Z-source converter to the battery simulator through the analysis of the output voltage range of Z-source. Analysis results show that the Z-source converter for battery simulator can implement buck-boost operation by using the shoot-through state, which is prohibited in the conventional AC/DC PWM converter as voltage source rectifier (VSR), it can overcome the voltage limitation of conventional battery simulator. A simple battery model is used for the battery simulator considering the internal series resistance and open circuit voltage (OCV), a voltage reference of battery simulator is generated by using a shepherd model. The validity of the proposed system which is battery simulator using Z-source converter is verified through simulation results.

Load and Source Battery Simulator Based on Z-Source Rectifier

This paper proposes a battery simulator (BS) based on a Z-source rectifier (ZSR), with the intention of emulating the discharge or charge characteristic of an actual lithium-polymer battery with high voltage and large capacity. The proposed BS is used for power testing for battery applications. The battery model, combined with a Shepherd model and a Thevenin model, is adopted to freely change the properties and specifications of the battery and to replicate the dynamic behavior of the battery, which is discretized to utilize the digital controller of the BS. The closed-loop voltage controller at the dc side of the ZSR is designed to emulate the rapid dynamic characteristics of the battery based on small-signal methods, considering the influence of the components of the impedance network. In this paper, battery voltage control algorithm (BVCA) is also utilized to minimize the voltage stress across switches while controlling two dc-side voltages within a wide range of output voltages. Simulation and experimental results are provided to verify the BS of the new feature and the proposed control method.