• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.350-352
• /
• 2007

Modularized charge equalization converter for HEV lithium-ion battery cells is proposed in this paper, in which intra-module and inter-module charge equalization can be achieved at the same time. For intra-module charge equalization, the conventional flyback DC/DC converters of low power and small size are employed, in which all of the primary sides are coupled in parallel for selective charge of the specific under charged cell within the module. For inter-module charge equalization, the flyback DC/DC converters are also added, in which all the secondary windings are electrically linked in parallel for automatic charge balancing among the modules. An engineering sample of forty cells hiring the proposed cell balancing scheme is implemented and its experimental result shows that the proposed modularized charge equalization circuit has good cell balancing performance.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.4
• /
• pp.321-329
• /
• 2015

The static synchronous compensator (STATCOM) of cascaded H-bridge configuration accompanying multiple separate DC sides is inherently subject to the problem of uneven DC voltages. These DC voltages in one leg can be controlled by adjusting the AC-side output voltage of each cell inverter, which is proportional to the active power. However, when the phase current is extremely small, large AC-side voltage is required to generate the active power to balance the cell voltages. In this study, an alternative zero-sequence current injection method is proposed, which facilitates effective cell balancing controllers at no load, and has no effect on the power grid because the injected zero sequence current only flows within the STATCOM delta circuit. The performance of the proposed method is verified through simulation and experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.7
• /
• pp.22-27
• /
• 2015

In this paper, the problem of voltage unbalancing in series-connected multiple electric double-layer capacitors(EDLCs) is studied. Good understanding of this problem is required in order to increase reliability and stability of an energy storage system comprising EDLCs. Existing methods to settle voltage unbalancing cannot mitigate the problem enough for each cell, since most method have been applied to each module. For equalizing between cells, Zener diode which is one of passive method have been well examined in literature. However, Zener have well not used in balancing due to heating problem. In addition, It is difficult to choose Zener diode fitted rating voltage of EDLC, because of its internal resistance. Thus, we proposed passive balancing using Zener diode by analyzing parasitic element of Zener and EDLC. To experimentally confirm the balancing effect, we compared in two occasions which are with and without passive. As a result, proposed passive balancing circuit mitigated unbalanced voltage gap between EDLCs.

• Proceedings of the KIPE Conference
• /
• 2003.11a
• /
• pp.193-196
• /
• 2003

For a power source of usual electronic devices such as PDA, smart phone, UPS and electric vehicle, the battery made of serially connected multiple cells is generally used. In this case, if there are some unbalanced among cell voltages, the total lifetime and the total capacity of the battery are limited to a lower value. To maintain a balanced condition in cells, an effective method of regulating the cell voltage in indispensable. In this paper introduced a method for battery balancing system using dissipation in the resistance.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.21 no.4
• /
• pp.351-355
• /
• 2016

Welding machines are high-capacity systems used in a low-frequency range using IGBT. As their system is similar to a large transformer, most welding machines suffer a great loss because of hard switching and vast leakage inductance. A voltage-balancing circuit is designed to overcome these shortcomings. This circuit can reduce the transformer size by making it into a high frequency and reducing the input voltage by half and by adopting a serial structure that connects two full-bridges in a series to use a MOSFET with a good property at high frequency. In addition, a Schottky diode is used in the primary rectifier to overcome the low efficiency of most welding machines. To use the Schottky diode with a reliably relatively low withstanding voltage, an active snubber is adopted to effectively limit the ringing voltage of the diode cut-off voltage.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.420-421
• /
• 2010

In this paper, a multi-module selective battery equalizer for series-connected Li-ion battery pack is proposed. Selective Equalizer (SE) scheme achieves smaller volume and lighter weight than individual cell equalizer (ICE) by minimizing the part count of bulky circuit element. However, SE scheme shows slow balancing speed when the voltage imbalance simultaneously occurs in more than one cell. The proposed multi-module overcomes the problem by employing multiple power converters. Prototype hardware is implemented and experimented with 14Ah battery cells to validate the performance of the proposed equalizer.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.2
• /
• pp.701-710
• /
• 2017

This paper presents a five-level PWM inverter using series and parallel connection of voltage sources. The alternative connection is done by an auxiliary circuit consisted of a switch, three diodes, and two batteries. The auxiliary circuit is located between input dc voltage source and H-bridge cell. Thanks to the auxiliary circuit, the proposed inverter synthesizes five-level output voltage in an effective way. Topologically both batteries are charged and discharged in the same rate, so it does not need to apply battery voltage balancing control method. Theoretical analysis of the proposed inverter is verified by computer-aided simulation and experiment based on a prototype of 1kW.

• Journal of Power Electronics
• /
• v.15 no.3
• /
• pp.660-669
• /
• 2015

This paper presents a control scheme with a focus on the combination of phase disposition pulse width modulation (PDPWM) and DC capacitor voltage control for a chopper-cell based modular multilevel converter (MMC) for the purpose of eliminating the time-consuming voltage sorting algorithm and complex voltage balancing regulators. In this paper, the convergence of the DC capacitor voltages within one arm is realized by charging the minimum voltage module and discharging the maximum voltage module during each switching cycle with the assistances of MAX/MIN capacitor voltage detection and PDPWM signals exchanging. The process of voltage balancing control introduces no extra switching commutation, which is helpful in reducing power loss and improving system efficiency. Additionally, the proposed control scheme also possess the merit of a simple executing procedure in application. Simulation and experimental results indicates that the MMC circuit together with the proposed method functions very well in balancing the DC capacitor voltage and improving system efficiency even under transient states.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.337-338
• /
• 2014

본 논문에서는 배터리 셀 간의 빠른 전하 균일화를 위한 새로운 셀 밸런싱 회로를 제안한다. 대칭적인 다권선 변압기를 이용하는 밸런싱 회로의 경우 셀들 간의 밸런싱 전류의 크기가 회로 내부 저항 및 변압기의 누설 인덕턴스에 의해 크게 제약 받고, 배터리 셀 간의 밸런싱이 이루어짐에 따라 충방전 전류가 감소한다는 단점이 있다. 본 논문에서는 보조 회로를 이용하여 밸런싱 전류를 부스트 업 시켜 빠르게 셀 간의 전하 밸런싱을 맞추어주는 회로를 제안한다. 이를 통해 회로 내부 저항의 영향을 줄이고 일정한 충방전 전류를 흘려보냄으로 빠르게 셀 전하들의 밸런싱을 맞출 수 있다.

• Journal of Power Electronics
• /
• v.19 no.4
• /
• pp.858-868
• /
• 2019

With the widespread use of modern clean energy, lithium-ion batteries have become essential as a more reliable energy storage component in the energy Internet. However, due to the difference in monomers, some of the battery over-charge or over-discharge in battery packs restrict their use. Therefore, a novel multiphase interleaved converter for reducing the inconsistencies of the individual cells in a battery pack is proposed in this paper. Based on the multiphase converter branches connected to each lithium battery, this circuit realizes energy transferred from any cell(s) to any other cell(s) complementarily. This flexible interlaced converter is composed of an improved bi-directional Buck-Boost circuit that is presented with its own available control method. A simulation model based on the PNGV model of fundamental equalization is built with four cells in PSIM. Simulation and experimental results demonstrate that converter and its control achieve simple and fast equalization. Furthermore, a comparison of traditional methods and the HNFABC equalization is provided to show the performance of the converter and the control of lithium-based battery stacks.