• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.205-208
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• 2020

This paper examines the approach, enabled by using SiC power devices, to unify the inverter design for central air conditioning (CAC) system for both single- and 3-phase input, and reduce the PFC inductor size to be PCB-mountable. By using SiC-instead of Si-diode in PFC stage, it is possible to increase the switching frequency from 16kHz to 60kHz to reduce the required PFC inductance from 0.93mH to 0.25mH, thus enable PCB-mounting of inductor. With the next step of using 1200V SiC MOSFET instead of Si-IGBT, the DC link voltage can be boosted from 311Vdc to 550Vdc in PFC stage, allowing the inverter and compressor used in 3-phase input CAC be used for single-phase input as well. Furthermore, using SiC MOSFET in inverter stage can further reduce total loss system total loss to 200.8 W. Simulation and experimental results are presented in the paper.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.78-82
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• 2014

Power Transformers with more than one secondary winding are not uncommon in industrial applications. But new classes of applications where very large number of independent secondaries are used are becoming popular in controlled converters for medium and high voltage applications. Cascade H-bridge medium voltage drives and Pulse Step Modulation (PSM) based high voltage power supplies are such applications. Regulated high voltage power supplies (Fig. 1) with 35-100 kV, 5-10 MW output range with very fast dynamics (${\mu}S$ order) uses such transformers. Such power supplies are widely used in fusion research. Here series connection of isolated voltage sources with conventional switching semiconductor devices is achieved by large number of separate transformers or by single unit of multi-secondary transformer. Naturally, a transformer having numbers of secondary windings (~40) on single core is the preferred solution due to space and cost considerations. For design and simulation analysis of such a power supply, the model of a multi-secondary transformer poses special problem to any circuit analysis software as many simulation softwares provide transformer models with limited number (3-6) of secondary windings. Multi-Secondary transformer models with 3 different schemes are available. A comparison of test results from a practical Multi-secondary transformer with a simulation model using magnetic component is found to describe the behavior closer to observed test results. Earlier models assumed magnetising inductance in a linear loss less core model although in actual it is saturable core made-up of CRGO steel laminations. This article discusses a more detailed representation of flux coupled magnetic model with saturable core properties to simulate actual transformers very close to its observed parameters in test and actual usage.

• 전기전자학회논문지
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• 제24권1호
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• pp.67-71
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• 2020

본 연구에서와 같이 전동기의 저속 영역 운전의 센서리스 기법으로 적합한 고조파 주입 센서리스 제어기법의 시뮬링크 시뮬레이션 모델을 제안한다. 본 모델에 적용되는 전동기는 영구자석 전동기이다. 또한, 다양한 고조파 주입 기법중 1kHz 구형파를 주입하는 기법을 사용한다. 고조파 주입에 따른 전동기의 전동기 상수의 변화는 시뮬링크에서 제공하는 전동기의 상수조정을 통해 구현한다. 시뮬링크의 함수와 라이브러리에서 제공하는 모델을 통해 센서리스 기법을 구현한다. 전류에 포함된 고조파 성분을 필터를 이용하여 추출하고, 추출된 파형을 이용하여 영구자석 전동기의 각도를 검출함을 보인다. 그리하여 1kW 영구자석 전동기에 적용된 시뮬레이션 파형에서의 전동기 각도 추정파형과 전동기 제어관련 파형을 통해 시뮬레이션 모델의 타당성을 보인다.

• 전력전자학회논문지
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• 제18권3호
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• pp.247-255
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• 2013

In this paper, a soft switching DC-DC converter for AC module type photovoltaic (PV) module integrated converter is proposed. A push-pull converter is suitable for a low voltage PV AC module system because the step-up ratio of a high frequency transformer is high and the number of primary side switches is relatively small. However, the conventional push-pull converters do not have high efficiency because of high switching losses by hard switching and transformer losses (copper and iron losses) by high turns-ratio of the transformer. In the proposed converter, primary side switches are turned on at zero voltage switching (ZCS) condition and turned off at zero current switching (ZVS) condition through parallel resonance between secondary leakage inductance of the transformer and a resonant capacitor. Therefore the proposed push-pull converter decreases the switching loss using soft switching of the primary switches. Also, the turns-ratio of the transformer can be reduced by half using a voltage-doubler of secondary side. The theoretical analysis of the proposed converter is verified by simulation and experimental results.

• Journal of Power Electronics
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• 제14권1호
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• pp.92-104
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• 2014

To insure stable operation and eliminate twice torque ripple, a topology for a six phase permanent magnet synchronous generator (SP-PMSG) with a neutral point connected together was analyzed in this paper. By adopting an extended transformation matrix, the mathematic model of the space vector control was established. The voltage and torque equations were deduced while considering the third harmonic flux and inductance. In addition, the suppression third harmonic method and the closed loop control strategy were proposed. A comparison analysis indicates that the cooper loss minimum method and the current magnitude minimum method can meet different application requirements. The voltage compensation amount for each of the methods was deduced which also takes into account the third harmonic effect. A simulation and experimental result comparison validates the consistency through theoretical derivation. It can be seen that all of the two control strategies can meet the requirements of post-fault.

• Journal of Power Electronics
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• 제14권1호
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• pp.165-174
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• 2014

The cascaded H-Bridge Dynamic Voltage Restorer (DVR) is used for protecting high voltage and large capacity loads from voltage sags. The LC filter in the DVR is needed to eliminate switching ripples, which also provides an accurate tracking feature in a certain frequency range. Therefore, the parameter optimization of the LC filter is especially important. In this paper, the value range functions for the inductance and capacitance in LC filters are discussed. Then, parameter variations under different conditions of voltage sags and power factors are analyzed. In addition, an optimized design method is also proposed with the consideration of multiple impact factors. A detailed optimization procedure is presented, and its validity is demonstrated by simulation and experimental results. Both results show that the proposed method can improve the LC filter design for a cascaded H-Bridge DVR and enhance the performance of the whole system.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.67-75
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• 2004

본 논문은 인덕턴스 성분을 포함한 단일 도선 및 트리 구조 RLC 연결선의 버퍼 삽입 방법을 제시한다. 이를 위해 먼저 CMOS 버퍼가 구동하는 단일 RLC 도선에 대한 시간 지연의 대수식을 제시한다. 이 수식은 현재의 서브마이크로미터 공정을 위한 n-th power law 기반에서 유도되었으며, 다양한 RLC 부하를 가지고 실험해 본 결과, 실제 SPICE 시뮬레이션 결과에 비해 최대 9％ 오차를 갖는 것으로 나타났다. 본 논문은 이 지연 시간 수식을 바탕으로 단일 도선 RLC 연결선을 여러 개로 나누는 버퍼 삽입에 관한 수식과 RLC 트리 연결선의 시간 지연을 최적화하기 위해 삽입될 버퍼의 사이즈를 결정하는 알고리듬을 제시한다. 제시된 버퍼 삽입 알고리듬은 0.25㎛ CMOS 공정의 트리 연결선에 적용하였으며, HSPICE 결과를 이용하여 정확도를 검증하였다.

• 대한전자공학회논문지SD
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• 제41권2호
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• pp.77-83
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• 2004

on-chip 상에서 발생하는 누화 잡음은 신호의 충실성을 위협하는 매우 중요한 요소이다. 따라서 본 논문에서는 최대 누화잡음의 크기를 예측하는 해석적인 방법을 제안한다. 정확한 잡음 수치를 예측하기 위해 연결선의 인덕턴스 성분을 고려하였고, 임의의 램프입력을 사용하였다. 또한 복잡한 누화 잡음 모형에서 최대 누화 잡음을 해석적으로 간단히 구하기 위해 가상의 소스 개념을 도입하였다. 된 연구에서 제안한 방법은 HSPICE 시뮬레이션 결과와 비교하여 최대 상대오차 4.3％ 이내의 정확도를 보였다. 따라서 본 연구는 신호 충실성 보장을 위한 다양한 설계 보조 도구 개발에 활용될 수 있을 것으로 본다.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권4호
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• pp.367-373
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• 2014

The most common current controller for the Switched Reluctance Motor (SRM) is the hysteresis controller. This method, however, suffers from such drawbacks as variable switching frequency, consequent audible noise and high current ripple. These disadvantages make this controlling method undesirable for many applications. The alternative solution is the PI controller. Since the fixed gain PI current controller can only be optimized for one operating point, and on the other hand, SR motor is highly nonlinear, PI controller gain should be adjusted according to incremental inductance. This paper presents a novel method for PI current controller gain adaptation which is simple and yields a good performance. The proposed controller has been implemented on a test bench using a eZdsp F28335 board. The performance of the current controller has been investigated in both simulation and experimental tests using a four-phase 8/6 4KW SRM drive system.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.131-134
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• 2002

In this work, we have developed a systematic way of utilizing the basic design tools for superconductive electronics. This include WRSPICE, XIC, margin program, and L-meter. Since the high performance analog-to- digital converter can be built with Rapid Single Flux Quantum (RSFQ) logic circuits the development of superconductive analog-to-digital converter has attracted a lot of interests as one of the most prospective area of the application of Josephson Junction technology. One of the main advantages in using Rapid Single Flux Quantum logic in the analog-to-digital converter is the low voltage output from the Josephson junction switching, and hence the high resolution. To design an 1-bit analog-digital converter, first we have used XIC tool to compose a circuit schematic, and then studied the operational principle of the circuit with WRSPICE tool. Through this process, we obtained the proper circuit diagram of an 1-bit analog-digital converter circuit. Based on this circuit we performed margin calculations of the designed circuits and optimized circuit parameters. The optimized circuit was laid out as a mask drawing. Inductance values of the circuit layout were calculated with L-meter. Circuit inductors were adjusted according to these calculations and the final layout was obtained.