• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.94-100
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• 2018

Generally, in a single-phase energy storage system (ESS) for households, AC ripple component with twice the fundamental frequency exists inevitably in the DC link voltage of single-phase PCS. In the grid-connected mode of a single-phase inverter, the AC ripple component in the DC link voltage causes low-order harmonics on grid-side current that deteriorates power quality on an AC grid. In this work, a control system adopting a feedforward controller is established to eliminate the AC ripple interference on the DC link side. Optimal battery nominal voltage design method is also proposed by considering the voltage loss and AC ripple voltage on DC link side in a single-phase ESS. Finally, the control system and battery nominal voltage design method are verified through simulations and experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1150-1154
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• 2003

The voltage profile during discharge of the zinc air battery has very flat pattern until reach to end of discharge voltage. But, when zinc air battery is discharged by high current, the discharge voltage and energy becomes low. Therefore, we focused on effects of catalyst size to solve this problems by increasing active sites of oxygen reduction reaction. The size of catalyst was reduced from 27 to l${\mu}{\textrm}{m}$ and we examined average discharge voltage, capacity, energy, resistance and characteristics during GSM pulse discharge of zinc air battery with change of current density. And we also measured porosity of the cathode according to the ASTM. So we have got improvement of average discharge voltage and energy when catalyst was minimized and we have got optimum size of catalyst at 5${\mu}{\textrm}{m}$.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.355-357
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• 2004

In this paper, to calculate accurate remaining volume, it presents how to figure out nickel-cadmium battery algorithm. A nickel-cadmium battery has widely been used in industrial field and to military. Recent high demands on the battery caused 'How to calculate accurate remaining volume is very important task to be solved. In this paper, it says it is useful using the terminal voltage change of the resistance that can be connected with the battery and the differentiation of the terminal voltage to calculate remaining volume of nickel-cadmium battery. And these can be used for volume inference data so that it is fuzzy based system which can be helpful to inference the remaining volume by the resistance of terminal voltage change. Because of electrochemical complexity, the volume calculating system is inferencing undirectly by experimentally built DB where as current the existing volume models are suffering to be adapted.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.169-170
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• 2013

One important test for formation and grading of the lithium-ion battery is to confirm the performance of the battery while discharging battery down to zero volts. In this paper, a novel charge/discharge converter with zero-voltage discharge function is proposed. The proposed converter is able to discharge the battery until the voltage reaches to zero volts. The phase-shifted full bridge method is used to charge the battery and the current-fed push-pull method with bidirectional switches is used for the discharge. The ZVS turn-on is achieved in the charge operation and the ZVS turn-off in the discharge operation. The performance of the system is verified by the experiments using lithium-ion batteries.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.256-258
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• 2007

A charge equalization converter with parallel-connected primary windings of transformers is proposed in digest. The proposed work effectively balance the voltage among Lithium-Ion battery cells despite each battery cell has low voltage gap compared with its SOC. The principle of the proposed work is that the equalizing energy from all battery strings moves to the lowest voltage battery through the isolated dc/dc converter controlled by the corresponding bi-directional switch. In this digest, a prototype of four Lithium-Ion battery cells is optimally designed and implemented, and experimental results show that the proposed method has excellent cell balancing performance.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.60-66
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• 2008

The operating voltage of Li/SOCl2 battery decrease immediately when we give a load battery stored for long time. It is called voltage delay. We cannot rapidly operate equipment at emergence situation because the voltage delays. So we have to overcome voltage delay. We reported the results improved voltage delay in this paper through the control of the carbon cathode forming density. It is the classic method in order to control of voltage delay that is coating polymer in the lithium surface or put in the additive to electrolyte. If the carbon cathode forming density decreases, the operating voltage of battery becomes to increasing because solution resistance of battery reduce.

• Journal of Power Electronics
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• v.17 no.1
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• pp.31-40
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• 2017

A novel voltage-fed single-stage power factor correction (PFC) full-bridge converter based on asymmetric phase-shifted control for battery chargers is proposed in this paper. The attractive feature of the proposed converter is that it can operate in a wide output voltage range without an output low-frequency ripple, which is indispensable in battery charger applications. Meanwhile, the converter can maintain a high power factor and a controllable dc bus voltage over a wide output voltage range. In this paper, the realization of PFC and the operation principle of asymmetric phase-shifted control are given. A small-signal analysis of the proposed single-stage power factor correction (PFC) full-bridge converter is performed. Experimental results obtained from a 1kW experimental prototype are given to validate the feasibility of the proposed converter. The PF is higher than 0.97 over the entire output voltage range with the proposed control strategy.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.95-99
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• 2017

The lifetime of a battery that supplies all the power required by a satellite in the eclipse is directly related to the lifetime of the satellite. Because the lifetime of the battery is influenced by the charging method of the battery, the power control unit that controls the charging of the battery should be designed in consideration of battery life. The battery charging is performed by controlling the charge current in the power control unit generated from the solar cell in the daytime. In order to prevent overcharge of the battery and for considering frequency of eclipse in each season, parameters related battery charging should be designed differently according to the season and to prevent over-current charging and over-voltage charging during charging, charge current is controlled by monitoring battery charge / discharge status, charge current amount, battery voltage, battery capacity, battery temperature and battery cell voltage. In satellite, tapering method is used to control charge current by reflecting each condition. In this paper, design battery charging algorithm of satellite power control unit using tapering charging method. convert the designed algorithm into a code that can be uploaded to satellites and verify the operation through testing in the established satellite environment.

• Journal of IKEEE
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• v.23 no.2
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• pp.695-703
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• 2019

In this paper, we propose a method to remove the circulating current which can occur in the parallel connection of the high voltage series connected battery module in the battery pack. The removal way is a method of inserting a module named VVSM (Variable Voltage Variable Module) using bidirectional DCDC converter and supercapacitor in place of one or some of the cascaded battery cells in the battery pack configuration. In this module, it operates like a battery cell that can be controlled at a desired voltage. VVSM is used to match the voltages of the cascaded battery modules very easily. To demonstrate the proposed method, a PSIM simulation for battery model is used. In addition, the module with only the battery cell connected in series and the module with the proposed VVSM are made, and the two modules were connected in parallel to measure the circulating current between the two modules. As a result, it was verified that the proposed method effectively suppressed the circulating current.

• Journal of IKEEE
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• v.23 no.1
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• pp.1-8
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• 2019

In this paper, the electrical characteristics with various C-rates are tested with a high power series battery pack comprised of 18650 cylindrical nickel cobalt aluminum(NCA) lithium-ion battery. The electrical characteristics of discharge capacity test with 14S1P battery pack and electric vehicle (EV) cycle test with 4S1P battery pack are compared and analyzed by the various of C-rates. Multiple linear regression is used to estimate voltage imbalance of 14S1P and 4S1P battery packs with various C-rates based on experimental data. The estimation accuracy is evaluated by root mean square error(RMSE) to validate multiple linear regression. The result of this paper is contributed that to use for estimating the voltage imbalance of discharge capacity test with 14S1P battery pack using multiple linear regression better than to use the voltage imbalance of EV cycle with 4S1P battery pack.