• Title/Summary/Keyword: Low-speed Power Loss

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A Study on Influence of Synchronous Rectification Switch on Efficiency in Totem Pole Bridgeless PFC (토템폴 브리지리스 PFC에서 동기정류 스위치의 효율 영향에 관한 연구)

  • Yoo, Jeong Sang;Ahn, Tae Young
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.4
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    • pp.108-113
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    • 2021
  • In this paper, a totem pole PFC was structured in two methods with FET and diode for low-speed switch while GaN FET was used for high-speed switch. Internal power loss, power conversion efficiency and steady-state characteristics of the two methods were compared in the totem pole bridgeless PFC circuit which is widely applied in large-capacity and high-efficiency switching rectifier of 500W or more. In order to compare and confirm the steady-state characteristics under equal conditions, a 2kW class totem pole bridgeless PFC was constructed and the experimental results were analyzed. From the experimental results, it was confirmed that the low-speed switch operation has a large difference in efficiency due to the internal conduction loss of the low-speed switch at a low input voltage. Especially, input power factor and load characteristic showed no difference regardless of the low-speed switch operation.

Analysis on the Core Loss and Windage Loss in Permanent Magnet Synchronous Motor for High-Speed Application (고속으로 운전되는 영구자석형 동기전동기의 철손 및 풍손 해석)

  • Jang, Seok-Myeong;Ko, Kyoung-Jin;Cho, Han-Wook
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.10
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    • pp.511-520
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    • 2006
  • Recently, more attention has been paid to the development of high-speed permanent magnet (PM) synchronous motors, since they are conductive to high efficiency, high power density, small size, and low weight. In high-speed PM machines, core loss and windage loss form a larger proportion of the total losses than usual in conventional mid- or low speed machines. This article deals with the analysis on the core loss and windage loss in PM synchronous motor for high-speed application. Using the data information from a manufacturer and non-linear curve fitting, this paper investigates the magnetic behavior and its core losses in the stator core using the electrical steels. And, the windage loss is calculated according to the variation of the rotational speed, motor inner pressure and temperature.

Model-Based Loss Minimization Control for Induction Generators - in Wind Power Generation Systems (모델 기반의 풍력발전용 유도발전기의 최소 손실 제어)

  • Abo-Khalil, Ahmed G.;Lee, Dong-Choon
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.7
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    • pp.380-388
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    • 2006
  • In this paper, a novel control algorithm to minimize the power loss of the induction generator for wind power generation system is presented. The proposed method is based on the flux level reduction, where the flux level is computed from the machine model for the optimum d-axis current of the generator. For the vector-controlled induction generator, the d-axis current controls the excitation level in order to minimize the generator loss while the q-axis current controls the generator torque, by which the speed of the induction generator is controlled according to the variation of the wind speed in order to produce the maximum output power. Wind turbine simulator has been implemented in laboratory to validate the theoretical development. The experimental results show that the loss minimization process is more effective at low wind speed and that the percent of power loss saving can approach to 25%. Experimental results are shown to verify the validity of the proposed scheme.

Loss Analysis of Three Phase Induction Motor Connected to Single Phase Source (단상전원에 접속된 3상 유도전동기의 손실분석)

  • Kim, Do-Jin;Jwa, Chong-Keun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.2
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    • pp.121-126
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    • 2008
  • This paper analyzes the losses of a Steinmetz connection three-phase induction motor which is supplied by a single-phase source. The T-type equivalent circuit which is taken no-load losses into account is used to determine phase converter capacitive reactances at starting and rated speed by using the condition of the minimum voltage unbalance. The starting and the operating capacitor are replaced at the slip of the same voltage unbalance factor points which are depicted using two capacitive reactances. The operation characteristics are investigated by comparing with those of three-phase balanced operation to find the feasibility of single-phase operation. To analyze the losses of this motor, the output power decrease factor(OPDF), the loss ratio(LR), the no load loss ratio(NLLR), the copper loss ratio(CLR), the stator copper loss ratio(SCLR), and the rotor copper loss ratio(RCLR) are defined and simulated in the whole slip range. The simulated results show that OPDF is maintained almost uniformly, LR is low at low speed and high at high speed, CLR is higher !ban NLLR, but CLR varies concavely and NLLR varies convexly at high speed, SCLR is low at low speed and high at high speed, but SCLR varies convexly at high speed, and RCLR is nearly opposite to SCLR.

Tip Clearance Effect of Low Mass Flow Rate High Specific Speed Centrifugal Impeller (저유량 고비속도 원심압축기 임펠러에서의 팁간극에 따른 효과)

  • Im, Kang-Soo;Kim, Yang-Gu;Kim, Kyi-Soon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.240-243
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    • 2008
  • In this paper, the design of Centrifugal Compressor which is used in sizes 50 horse power has 8 pressure ratio and numerical analysis of the flow within compressor varying tip clearance length are performed. To get high pressure ratio with low power the exit height of impellers is low but compressor has very high speed of revolution. So compressor has high specific speed although mass flow rate is very small. The shape of impellers at the first stage is carried out. Flow and performance characteristics of impellers has been analyzed by using a commercial CFD program, $Fine^{TM}$/turbo. The result shows that loss coefficient is affected by tip clearance length and compressor has proper tip clearance length. It is possible to decrease loss by selecting apt tip clearance length.

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CoolSiCTM SiC MOSFET Technology, Device and Application

  • Ma, Kwokwai
    • Proceedings of the KIPE Conference
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    • 2017.07a
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    • pp.577-595
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    • 2017
  • ${\bullet}$ Silicon Carbide (SiC) had excellent material properties as the base material for next generation of power semiconductor. In developing SiC MOSFET, gate oxide reliability issues had to be first overcome before commercial application. Besides, a high and stable gate-source voltage threshold $V_{GS(th)}$ is also an important parameter for operation robustness. SiC MOSFET with such characteristics can directly use existing high-speed IGBT gate driver IC's. ${\bullet}$ The linear voltage drop characteristics of SiC MOSFET will bring lower conduction loss averaged over full AC cycle compared to similarly rate IGBT. Lower switching loss enable higher switching frequency. Using package with auxiliary source terminal for gate driving will further reduce switching losses. Dynamic characteristics can fully controlled by simple gate resistors. ${\bullet}$ The low switching losses characteristics of SiC MOSFET can substantially reduce power losses in high switching frequency operation. Significant power loss reduction is also possible even at low switching frequency and low switching speed. in T-type 3-level topology, SiC MOSFET solution enable three times higher switching freqeuncy at same efficiency.

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Optimal Efficiency Control of Induction Generators in Wind Energy Conversion Systems using Support Vector Regression

  • Lee, Dong-Choon;Abo-Khalil, Ahmed. G.
    • Journal of Power Electronics
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    • v.8 no.4
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    • pp.345-353
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    • 2008
  • In this paper, a novel loss minimization of an induction generator in wind energy generation systems is presented. The proposed algorithm is based on the flux level reduction, for which the generator d-axis current reference is estimated using support vector regression (SVR). Wind speed is employed as an input of the SVR and the samples of the generator d-axis current reference are used as output to train the SVR algorithm off-line. Data samples for wind speed and d-axis current are collected for the training process, which plots a relation of input and output. The predicted off-line function and the instantaneous wind speed are then used to determine the d-axis current reference. It is shown that the effect of loss minimization is more significant at low wind speed and the loss reduction is about to 40% at 4[m/s] wind speed. The validity of the proposed scheme has been verified by experimental results.

Highly Efficient AC-DC Converter for Small Wind Power Generators

  • Ryu, Hyung-Min
    • Journal of Power Electronics
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    • v.11 no.2
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    • pp.188-193
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    • 2011
  • A highly efficient AC-DC converter for small wind power generation systems using a brushless DC generator (BLDCG) is presented in this paper. The market standard AC-DC converter for a BLDCG consists of a three-phase diode rectifier and a boost DC-DC converter, which has an IGBT and a fast recovery diode (FRD). This kind of two-stage solution basically suffers from a large amount of conduction loss and the efficiency greatly decreases under a light load, or at a low current, because of the switching devices with a P-N junction. In order to overcome this low efficiency, especially at a low current, a three-phase bridgcless converter consisting of three upper side FRDs and three lower side Super Junction FETs is presented. In the overall operating speed region, including the cut-in speed, the efficiency of the proposed converter is improved by up to 99%. Such a remarkable result is validated and compared with conventional solutions by calculating the power loss based on I-V curves and the switching loss data of the adopted commercial switches and the current waveforms obtained through PSIM simulations.

A PWM Control Strategy for Low-speed Operation of Three-level NPC Inverter based on Bootstrap Gate Drive Circuit (부트스트랩 회로를 적용한 3-레벨 NPC 인버터의 저속 운전을 위한 PWM 스위칭 전략)

  • Jung, Jun-Hyung;Ku, Hyun-Keun;Im, Won-Sang;Kim, Wook;Kim, Jang-Mok
    • The Transactions of the Korean Institute of Power Electronics
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    • v.19 no.4
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    • pp.376-382
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    • 2014
  • This paper proposes the pulse width modulation (PWM) control strategy for low-speed operation in the three-level neutral-point-clamped (NPC) inverters based on the bootstrap gate drive circuit. As a purpose of the cost reduction, several papers have paid attention to the bootstrap circuit applied to the three-level NPC inverter. However, the bootstrap gate driver IC cannot generate the gate signal to the IGBT for low-speed operation, because the bootstrap capacitor voltage decreases under the threshold level. For low-speed operation, the dipolar and partial-dipolar modulations can be the effective solution. However, these modulations have drawbacks in terms of the switching loss and THD. Therefore, this paper proposes the PWM control strategy to operate the inverter at low-speed and to minimize the switching loss and harmonics. The experimental results are presented to verify the validity on the proposed method.

A Study of the Digital Phase-shift Resonant Converter to Reduce the conduction Loss and Stress of the Switching Device (스위칭 소자의 전도손실과 스트레스를 저감하기 위한 디지털 위상천이 공진형 컨버터에 관한 연구)

  • Shin, Dong-Ryul;Hwang, Young-Min;Kim, Dong-wan;Woo, Jung-In
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.51 no.1
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    • pp.10-17
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    • 2002
  • Due to the development of information communication field, the interest of the SMPS(Switched Mode Power Supply) is increased. The size and weight of SMPS are decided by inductor, capacitor and transformer. Thus, the low loss converter which is operated in high speed switching is required. The resonant FB DC-DC converter is able to operate in high speed switching and apply to high power field because the switching loss is low. In this thesis, it is proposed to control strategy for constant output power of resonant FB DC-DC converter in variable input voltage. The proposed control system is a digital I-PD type control and apply to phase-shift resonant type controller. The output voltage tracks reference without steady state error in variable input voltage. The validity of proposed control strategy is verified from results of simulation and experiment.