• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.10
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• pp.59-68
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• 2013

This paper proposes the boost type bidirectional DC/DC converter with high efficiency for electric vehicle using an interleave method. This interleave method can reduce the system size because it reduces the ripple of output voltage and input current with no add to extra filter. Proposed system is consist of two converters and applies to interleaved method through phase shift to each converter. And it implements the high boost through voltage double and series construction of output port. Also, it reduces the price and increases the efficiency as operating the ZCS by leakage inductance of transformer and capacitor of voltage double with not add special reactor. Proposed DC/DC converter using interleave method is proved the validity through the result of PSIM simulation and experiment of 5kW DC/DC converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.5
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• pp.404-413
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• 2017

This paper suggests an isolated PFC converter for electric vehicle (EV) chargers with wide-output voltage range. The proposed converter is based on voltage-fed full-bridge structure. All the harmonic and output controls are performed by secondary and primary switches are only operated under a fixed frequency with 50% duty-ratio. In addition, harmonic modulation technique is adopted to obtain a near unity power factor without input current monitoring. The feasibility of the proposed charger has been verified with a 10-kW prototype.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.5
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• pp.313-320
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• 2018

This study proposes a new voltage balancer with bidirectional DC-DC converter function. The proposed balancer can serve as a voltage balancer and a bidirectional DC-DC converter. Thus, the balancer can be applied to battery management systems or fast chargers in electric vehicles (EVs) charging stations while balancing bipolar DC bus voltages. The proposed system has unlimited voltage balancing range unlike the conventional voltage balancing control using a three-level DC-DC converter. A comparison of the voltage balancing range between the proposed and conventional scheme is explored to confirm this superiority. Simulation and experimental results are provided to validate the effectiveness of the proposed system.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.198-199
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• 2019

이 논문에서 제안하고자 하는 컨버터는 태양광 모듈이 결합된 Phase-shifted Full-bridge(PSFB) 컨버터이다. 기존 전기자동차의 전력변환 시스템에는 고전압 배터리와 저전압 배터리간 전력전달을 위한 DC-DC 컨버터가 존재한다. 저전압 배터리 충전에 있어 고전압 배터리 외에 태양광 모듈 컨버터를 사용하여 고전압 배터리 사용량을 낮출 수 있다. 이 논문에서는 기존의 PSFB 컨버터의 2차측에 태양광 모듈과 스위치하나를 추가하여 태양광 Buck Converter를 구성하였고 PSFB컨버터의 출력 인덕터와 Synchronous switch를 사용하게 되어 소자 수를 절감하였다. 또한 PSFB 동작 시 1차측 전류가 Free wheeling하는 구간에서 태양광 Buck converter를 동작함으로써 고전압 배터리와 태양광 모듈에서 동시에 저전압 배터리로 전력공급이 가능하게 하였다.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.223-224
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• 2018

본 논문에서는 전기자동차용 저전압 배터리 충전기(Low-voltage DC-DC Converter, LDC)에 적합한 입력 직렬-출력 병렬 구조의 능동 클램프 포워드 컨버터의 모델링 및 제어기 설계를 제안한다. 제안하는 컨버터는 모든 스위치에서 소프트 스위칭을 성취하기 때문에 높은 효율을 달성할 수 있다. 또한 누설 인덕턴스의 영향을 포함한 컨버터의 정확한 소신호 모델을 통하여 모델링 기반의 제어기 설계를 제시한다. 제어기의 시뮬레이션 및 3.2kW급 시작품의 실험을 통하여 제안하는 컨버터의 성능을 검증하였다.

• Journal of Power Electronics
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• v.17 no.2
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• pp.490-500
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• 2017

Fuel cell (FC) is a promising power supply in electric vehicles (EV); however, it has poor dynamic performance and short service life. To address these shortcomings, a super capacitor (SC) is adopted as an auxiliary power supply. In this study, the frequency decoupling control method is used in electric vehicle energy system. High-frequency and low-frequency demand power is provided by SC and FC, respectively, which makes full use of two power supplies. Simultaneously, the energy system still has rapidity and reliability. The distributed power system (DPS) of EV requires DC-DC converters to achieve the desired voltage. The stability of cascaded converters must be assessed. Impedance-based methods are effective in the stability analysis of DPS. In this study, closed-loop impedances of interleaved half-bridge DC-DC converter and phase-shifted full-bridge DC-DC converter based on the frequency decoupling control method are derived. The closed-loop impedance of an inverter for permanent magnet synchronous motor based on space vector modulation control method is also derived. An improved Middlebrook criterion is used to assess and adjust the stability of the energy system. A theoretical analysis and simulation test are provided to demonstrate the feasibility of the energy management system and the control method.

• Journal of Power Electronics
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• v.11 no.4
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• pp.479-489
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• 2011

The bidirectional dc-dc converter, being the interface between Energy Storage Element (ESE) and DC bus, is an essential component of the power management system for vehicle applications including electric vehicle (EV), hybrid electric vehicle (HEV), and fuel cell vehicle (FCV). In this paper, a novel multiphase bidirectional dc-dc converter interfacing with battery to supply and absorb the electric energy in the FCV system was studied with the help of real time digital simulator (RTDS). The mathematical models of fuel cell, battery and dc-dc converter were derived. A power management strategy was developed and first simulated in RTDS. A Power Hardware-In-the-Loop (PHIL) simulation using RTDS is then presented. The main challenge of this PHIL is the requirement for a highly dynamic bidirectional Simulation-Stimulation (Sim-Stim) interface. This paper describes three different interface algorithms. The closed-loop stability of the resulting PHIL system is analyzed in terms of time delay and sampling rate. A prototype bidirectional Sim-Stim interface is designed to implement the PHIL simulation.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.198-200
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• 2018

In this paper a single-stage single-phase differential type isolated AC-DC converter is proposed. This converter eliminates the requirement to use bulky electrolytic capacitor from the system and at the same time provides DC charging by employing the AC Power Decoupling waveform control method. All the switches of the converter achieve ZVS turn on during half line cycle and all diodes achieve ZCS turn off during entire line cycle. A conventional controller is implemented for PFC control and output regulation, whereas a power decoupling controller is added to compensate $2^{nd}$ harmonic ripple power. In addition, an interleaving technique is applied to increase the power range of the converter and reduce the input inductor size. In the end simulation verification is performed and results are obtained for 6.6KW.

• Journal of Power Electronics
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• v.3 no.4
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• pp.230-238
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• 2003

Electric vehicles (EV) demands for greater acceleration, performance and vehicle range in pure electric vehicles plus mandated requirements to further reduce emissions in hybrid electric vehicles (HEV) increase the appeal for combined on-board energy storage systems and generators. And the power electronics plays an important role in providing an interface between fuel cells (FC) and loads. This paper deals with a multiple input DC-DC power converter devoted to combine the power flowing of multi-source on energy systems. The multi-source is composed of (i) FC system as a prime power demands, (ii) super capacitor banks as energy storage devices for high and intense power demands, (iii) superconducting magnetic energy storage system (SMES), (iv) multiple input DC-DC power converter and (v) a three phase inverter-fed permanent magnet synchronous motor as a drive. In this system, It is used super capacitor banks and superconducting magnetic energy replaces from the battery system. The modeling and transient performance simulation is effective for reducing transient influence caused by sudden charge of effective load. The main purpose of power electronic converters is to convert the DC power output from the fuel cell and other to a suitable AC voltage, which can be connected to electric loads directly (PMSM). The fuel cell and other output is connected to the DC-DC converter, which regulates the DC link voltage.

• Journal of IKEEE
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• v.23 no.1
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• pp.261-265
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• 2019

We analyze the failure rate change of a conventional bidirectional converter and a modified one which moves an output capacitor towards propulsion battery. We analysis of the circuit structural homogeneity and the difference between both converters, and confirm that the capacitor working voltage is reduced by changing the capacitor position. After obtaining the capacitor failure rate according to voltage stress factor and operating temperature, it is applied to the fault-tree of the bidirectional converter to obtain the overall failure rate of the converter. We analyzes the advantages and disadvantages of design changes by comparing and analyzing the failure rate and mean time between failures (MTBF) according to operating temperature and capacitance value.