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Highly isolated switching mode power supply for solid-state transformers in railway vehicles
Lee, Yejun,Bu, Hanyoung,Lee, Dohong,Cho, Younghoon The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.4
This paper discusses an isolated switching mode power supply (SMPS) with an AC 30 kV<sub>rms</sub> insulation capability for application to the solid-state transformers (SSTs) in railway vehicles. The insulation capability of the SMPS should be higher than AC 25 kV<sub>rms</sub> for application at the SSTs in railway vehicles. The proposed highly isolated SMPS is superior to commercial isolated power supplies with low insulation capability, which is normally less than 20 kV. The input side of the proposed isolated SMPS is physically separated from its output side by a specially designed miniature high-frequency (HF) transformer to obtain high insulation capability. The core of the miniature HF transformer is separated by insulation material. The primary and secondary coils are wound around each separated core. A CLLC resonant converter that consists of a primary resonant capacitor (C), two inductors (LL), and a secondary resonant capacitor (C) is applied as the proposed isolated SMPS topology to improve the output voltage regulation performance, which varies due to a large leakage inductance derived from the airgap of the proposed miniature HF transformer. Experiments are carried out to verify the CLLC resonant converter of the proposed isolated SMPS. Electrostatic finite element method (FEM) simulations and high potential (HiPot) tests are carried out to verify the AC 30 kV<sub>rms</sub> insulation capability of the proposed isolated SMPS. The electrostatic FEM simulations demonstrate the DC 42.43 kV insulation capability, and the HiPot tests verify the insulation capability from AC 5 kV<sub>rms</sub> to AC 30 kV<sub>rms</sub>.
Lee, Taeyeong,Kim, Hokyeong,Lee, Nayoung,Chin, Taehoon,Bu, Hanyoung,Cho, Younghoon The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.3
This paper evaluates the dv/dt performances of the motor input terminal fed by a gallium nitride (GaN) field effect transistor (FET) matrix converter for variable frequency drive applications. To limit the high dv/dt caused by the fast switching operation of GaN devices, a dv/dt filter is employed. With the dv/dt filter, the input terminal voltage can meet the standards suggested by National Electrical Manufacturers Association. On the other hand, when a GaN FET matrix converter and an electric motor are connected by a long cable, the parasitic impedance of the cable varies. This impedance mismatch results in voltage reflection (VR), and this VR causes a large surge voltage with severe ringing at the motor input terminal. Even in this case, the dv/dt filter effectively restricts the dv/dt of the voltage applied to the electric motor. Frequency response results are obtained through the transfer functions of the filter according to the applied position. Experiments are carried out using a 220 V/60 Hz induction motor and a GaN FET-based matrix converter prototype. The dv/dt filter performance with two positions and cable lengths of 5 m and 25 m is evaluated by comparing the obtained experimental results with the frequency response.
고체윤활제 Cu₂S첨가 청동의 미끄럼 마찰마모특성 연구
이한영(Hanyoung Lee),김태준(Taejun Kim),조용재(Yongjae Cho) 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.39 No.-
MOS₂ is a well-known metal sulfide applied as solid lubricants and an additive to prolong the life of sintered bearings under severe conditions. However. the high price of MoS₂ limited its wide application. This study is aimed to investigated the possibility for application to solid lubricants for Cu₂S as a substitute of MoS₂. Bronzes added Cu₂S and MoS₂ are produced by powder metallurgy in this study. and then evaluated their friction and wear properties. The sliding wear test using pin-on-disc type machine. was conducted at several sliding speeds for three type test pieces. bronze and bronzes added Cu₂S/MoS₂. Addition of Cu₂S to bronze leads to relatively good friction and wear properties. although it is not so good as addition of MoS₂. But the properties of bronze added Cu₂S would be not suitable for the condition under the high sliding speed.
Bu, Hanyoung,Lee, Yejun,Cho, Younghoon,Kim, Myung-Yong,Lee, Eunsoo,Park, Jin-Hyuk The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.8
This paper proposes a neutral section passing strategy for preventing the inrush current of an electric railway vehicle (ERV) with a solid-state transformer (SST). This inrush current is not generated when the ERV passes the neutral section by maintaining a dc-link voltage at a constant level that is higher than the peak voltage of an electric railway feeder using regenerative energy from the ERV. Depending on the position of the ERV, the control strategies and modes are changed. When the ERV passes the neutral section, the regenerative energy from the ERV charges the dc-link voltage. A dc-ac converter that operates a traction motor takes charge of the dc-link voltage control in the regeneration operation. Simulation results show that the proposed strategy can protect the SST from inrush current when the ERV passes the neutral section. Experiments have been carried out with a scaled-down prototype. Experimental results verify the performance of the proposed neutral section passing strategy.
이한영(Hanyoung Lee) 대한전기학회 2010 정보 및 제어 심포지엄 논문집 Vol.2010 No.10
산란광을 이용한 차량용 우적감지 센서는 광도파관을 이용하는 일반 우적감지 센서와는 달리 수신되는 신호가 극히 미약하므로 이를 신호 대 잡음비를 저하시키지 않으면서 고감도로 수신할 필요가 있다. 제안하는 산란광을 이용한 우적감지 센서용 광송수신 장치는 간섭필터를 사용하여 주변광의 영향을 최소화 하였으며 전기적 신호 증폭단계에서 반송파 주파수를 이용한 변조방법과 확장디지털 신호 변환법을 사용하여 신호 대 잡음비를 최대로 유지하였다. 스프레이어를 이용한 가상강우 환경에서 제작된 광송수신 장치를 장착한 산란광 감지방식 우적감지 센서는 빗방울 감지시 불필요한 궤환이나 혼신 없이 차량용 우적감지 센서로 이용할 수 있는 가능성을 보여 주었다.