• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1953-1955
• /
• 1999

The effects of the local lifetime control on the characteristics of IGBT are investigated using the 2-dimensional device simulator, MEDICI. Many lumped resistive turn-off simulations are carried out to analyze the effects of the minority carrier lifetime, the width, and the position of the region with a reduced local minority carrier lifetime. As a result of these simulations, it is concluded that the on state voltage drop$(V_{CE,SAT})$ is only slightly increased while the switching behavior is greatly improved if the low lifetime region is properly set. And these results are compared with IGBTs having uniform lifetime.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.718-722
• /
• 2001

This paper proposes an SSSC based on multi-bridge inverters in PWM scheme. The proposed system consists of 6 H-bridge inverter modules per phase. The dynamic characteristic of proposed system was analyzed by simulation with EMTP codes, assuming that the SSSC is inserted in the 154-kV transmission line of one-machine-infinite-bus power system. The feasibility of hardware implementation was verified through experimental works with a scaled-model. The proposed system can be directly inserted in the transmission line without coupling transformers, and has flexibility in expanding the operation voltage by increasing the number of H-bridges.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.977-979
• /
• 2001

The application of SRM(Switched Reluctance Motor) is dramatically increasing due to a simple mechanical structure, high efficiency and a good high speed characteristics. Generally, turn-off angle of power switch must be limited the demagnetization period. To control high conduction ratio in motor operation and regenerative voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper proposes multi-level inverter to have a maximum conduction ratio of SRM. The proposed method is verified by experiment.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.737-739
• /
• 2015

In this paper, a novel method of sensorless control scheme is proposed to apply on a single phase hybrid SRM used in high speed operation. The proposed method utilizes beneficially permanent magnet field whose performance is motor parameter independent to estimate the rotor position. Also, the current slope is adopted to complete the sensorless control when the motor running with heavy torque at high speed condition. Through this approach, the adjustable turn on/off position can be achieved without prior knowledge of inductance profile which is always employed by many sensorless schemes. And this paper may offer an available method to do the sensorless control in hybrid SRM used for high speed running.

• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.213-214
• /
• 2015

In this paper, a novel method of sensorless control scheme is proposed to apply on a single phase hybrid SRM used in high speed operation. The proposed method utilizes beneficially permanent magnet field whose performance is motor parameter independent to estimate the rotor position. The differential value of back-EMF is used to detect its peak point when there is no current conducting in the winding. Through this approach, the adjustable turn on/off position can be achieved without prior knowledge of inductance profile which is always employed by many sensorless schemes. And this paper may offer an available method to do the sensorless control in hybrid SRM used for high speed running.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.12
• /
• pp.1264-1270
• /
• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After making symmetric thyristor dies with a voltage rating of 1,600 V from 350 $\mu$m thickness of 60 $\Omega$ㆍcm NTD-Si wafer and 200 $\mu$m width of n-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7 MeV proton beam showed a superior trade-off relationship of $V_{TM}$ = 1.55 V and $t_{q}$ = 15 $\mu$s attributed to a very narrow layer of short carrier lifetime(～1 $\mu$s) in the middle of its n-base drift region. To explain the small increase of $V_{TM}$ , we will introduce the effect of carrier compensation at the low carrier lifetime region by the diffusion current.ffusion current.t.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.271-275
• /
• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After fabricating symmetric thyristor dies with a voltage rating of 1,600V from $350{\mu}m$ thickness of $60{\Omega}cm$ NTD-Si wafer and $200{\mu}m$ width of N-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7MeV proton beam showed a superior trade-off relationship of $V_{TM}=1.55V\;and\;t_q=15{\mu}s$ attributed to a very narrow layer of short carrier lifetime(${\sim}1{\mu}s$) in the middle of its N-base drift region. To explain the small increase of $V_{TM}$, we will introduce the effect of carrier compensation by the diffusion current at the low carrier lifetime region.

• Journal of Integrative Natural Science
• /
• v.11 no.1
• /
• pp.44-50
• /
• 2018

In this paper, we propose a context-aware power management (CPM) scheme using beacons to reduce the power consumption of personal computers (PCs). In the proposed CPM scheme, the PC, smartphone, control server, and Internet of Things (IoT) device are necessary. PC users first log in the control server using their smartphones and select PCs to turn on. Then, the selected PCs automatically go into three different modes, i.e., sleep, shutdown, and standby power off modes, in order when the PC users leave the PCs without turning off them. Further, we develop a testbed with the proposed CPM scheme using the Arduino with Bluetooth low energy (BLE) and relay modules. Finally, it is shown that the proposed CPM scheme outperforms the conventional scheme in terms of the power consumption.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.60 no.4
• /
• pp.246-252
• /
• 2011

In this paper proposes the soft-switching boost converter and MPPT control for improving the efficiency of PV system. The proposed converter designed H-bridge auxiliary resonant circuit. By this circuit, all of the switching devices perform the soft switching under the zero voltage and zero current condition. Therefore the periodic switching losses can be decreased at turn on, off. The soft switching boost converter designs for 1.5[kW] solar module of the power conversion. Thus, this soft switching boost converter is simulated by MATLAB simulation using Newton-Method algorithm. As a result, Proposed Soft Switching Converter compared to a typical boost converter switching loss was reduced about 61%. And the overall system efficiency was verified to increase about 3.3%.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.35C no.2
• /
• pp.22-28
• /
• 1998

A $g_m$-control technique using a new electronic zener diode (EZD) for CMOS rail-torail input stages is presented. A regulated CMOS inverter is used as an EZD to obtain a constant-$g_m$ input stage. The turn-off characteristic of the proposed EZD is better than that of the existing EZD using two complementarey diodes, and thus, better $g_m$-control can be achieved. With this input stage, a 3V constant-$g_m$ rail-to-rail CMOS op-amp has been designed and fabricated using a $0.8\mu\extrm{m}$single-poly, double-metal CMOS process. Measurements results show that the $g_m$ variation is about 6% over the entire input common-mode range, and the op-amp has a dc gain of 88dB and a unity-gain frequency of 4MHz for $C_L=20pF, R_L=10k\Omega$