• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.98-100
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• 2007

This paper proposes a robust digital controller for PWM voltage source inverter using CRA method. The usual inverter controller for the operation of constant voltage and constant frequency consists of a double looped PI controller for the outer voltage controller and the inner current controller, of which the order of characteristic polynomial is high and so the gain tuning is difficult. Considering the limited switching frequency of the devices and sampling frequency of the digital controller, the gain tuning is usually based on the engineering experiences with the try and error method. In this paper, the error-space approach is used to get the system model including the controller with low order, and the characteristic ratio assignment (CRA) method is proposed for the design of robust controller which has the advantage to design the optimal gain to meet the referenced response and overshoot within the limit range. The PSiM simulation and experience results are shown to verify the validity of the proposed controller.

• Journal of IKEEE
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• v.17 no.3
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• pp.267-274
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• 2013

This paper presents a design of LLC resonant converter IC for LED backlight unit based on PFM/PWM dual-mode feedback. Dual output LLC resonant architecture with a single inductor is proposed, where the master output is controlled by the PFM and slave output is controlled by the PWM. To regulate the master output PFM is used as feedback to control the frequency of the power switch. On the other hand, PWM feedback is used to control the pulse width of the power switch and to regulate the slave output. This chip is fabricated in 0.35um 2P3M BC(Bipolar-CMOS-DMOS) Process and the die area is $2.3mm{\times}2.2mm$. Current consumptions is 26mA from 5V supply.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.2
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• pp.166-173
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• 2012

Plug-in Hybrid Electric Vehicle is driven by the engine, the primary traction motor, and the secondary auxiliary motor generating the electric power for battery charging. Secondary auxiliary motor should be connected to the engine or separated from the engine by the clutch system. This paper presents the position controller of the BLDC motor for the clutch system of Plug-in Hybrid Electric Vehicle. The BLDC motor can be applied to the clutch system in spite of it's low accuracy of the position control due to high gear ratio between the clutch and the motor. Since the attachment and the detachment between the motor and the engine should be carried out within 0.3 seconds, the position controller with fast acceleration and deceleration is implemented. For the torque control with braking operation for the BLDC motor, the modified bipolar PWM method with low current ripple compared to the conventional unipolar PWM is presented. The position control performance of the BLDC motor for the clutch system is verified through the simulation and experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.168-174
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• 2016

In this paper, current control using PI controller in the synchronous reference frame is analyzed through the relationship among bandwidth, resonance frequency, and sampling frequency in the grid-connected inverter with LCL filter. Stability is investigated by using bode plot in frequency domain and root locus in discrete domain. The feedback variable is the grid current, which is regulated by the PI controller in the synchronous reference frame. System delay is modeled as 1.5Ts, which contains computational and PWM modulator delay. Two resonance frequencies are given at 815 Hz and 3.16 kHz from LCL filter parameters. Sufficient phase and gain margins can be obtained to guarantee stable current control, in case that resonance frequency is above one-sixth of the sampling frequency. Unstable current control is performed when resonance frequency is below one-sixth of the sampling frequency. Analysis results of stability from frequency response and discrete response is the same regardless of resonance frequency. Finally, stability of current control based on theoretical analysis is clearly verified through simulation and experiment in grid-connected inverters with LCL filter.

• Journal of Power Electronics
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• v.11 no.3
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• pp.271-278
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• 2011

This paper presents a LLC resonant controller IC for secondary side control without external active devices to achieve low profile and low cost LED back light units. A gate driving transformer is adopted to isolate the primary side and the secondary side instead of an opto-coupler. A new integrated dimming circuitry is proposed to improve the dynamic current control characteristic and the current density of a LED for the brightness modulation of a large screen LCD. A dual-slope clock generator is proposed to overcome the frequency error due to the under shoot in conventional approaches. This chip is fabricated using 0.35 ${\mu}m$ BCD technology and the die size is $2{\times}2\;mm^2$. The frequency range of the clock generator is from 50 kHz to 500 kHz and the range of the dead time is from 50 ns to 2.2 ${\mu}s$. The efficiency of the LED driving circuit is 97 % and the current consumption is 40 mA for a 100 kHz operation frequency from a 15 V supply voltage.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.147-149
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• 2004

This paper presents a new velocity estimation strategy of a non-salient permanent magnet synchronous motor(PMSM) drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system which has the information of rotor position error. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error to zero. For zero and low speed operation, the PI gains of rotor position tracking controller have a variable structure. The PI tuning formulas are derived by analyzing this control system using the frequency domain specifications such as phase margin and bandwidth assignment.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.8
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• pp.536-543
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• 2000

The photovoltaic power generation system has a great future as clean energy instead of fossil fuel which has many environmental problems such as exhausted gas or air pollution. In a utility interactive photovoltaic generation system, a three-phase inverter is used for the connection between the photovoltaic array and the utility. This paper present a three phase inverter for photovoltaic power system with current controller, voltage controller, PLL Control system and the Phase detector of Interactive Voltage by using dq transformation. The proposed inverter system provides a sinusoidal ac current for domestic loads and the utility line with unity power factor.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.42-53
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• 1996

The paper presents a speed control system of vector controlled induct- ion motor using neural networks. The main feature of proposed speed control system is a Neural Network Controller(NNC) which supplies torque current to induction motor and Neural Network Emulator(NNE) which captures the forward dynamics of induction motor. A back propagation training algorithm is employed to train the NNE and NNC. In order to determine the NNC output error, plant(induction motor) output error can be back propagated through the NNE. The NNC and NNE for speed control of vector controlled induction motor is carried out by TMS320C30 DSP and IGBT current regulated PWM inverter. Through computer simulation and experimental results, it is verified that proposed speed control system is robust to the load variation. (author). refs., figs.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.381-383
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• 2000

The photovoltaic power generation system has a great future as clean energy instead of fossil fuel which has many environmental problems such as exhausted gas or air pollution. In a utility interactive photovoltaic generation system, a three-phase inverter is used for the connection between the photovoltaic array and the utility. This paper presents a three phase inverter for photovoltaic power system with current controller, voltage controller, PLL control system and the phase detector of interactive voltage by using da transformation. The proposed inverter system provides a sinusoidal ac current for domestic loads and the utility line with unity power factor. The results of the operated from January to October show the system characteristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.525-535
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• 2004

In this paper, a two-phase DZRCD(Dual Zero Vector Modes RCD) technique is proposed to develope the problem of a conventional two-phase RCD-PWM (Random Centered Distribution PWM) which gives the power spectra of narrow band range in the high modulation index (M). In the proposed DZRCD technique, the zero vector $V_0$ is selected as $V_0$(111) for M$\geqq$0.8. Also, $V_0$ is selected as $V_0$(000) for the modulation indices < 0.8. For the unplementation of the proposed method, a 16-bit micro-controller Cl67 was used and the experiments were conducted with the 1.5kw induction motor under no load condition. The experimental results show that the voltage / current spectra is spread to a wide band range, and the switching noise of motor is reduced by the proposed method compared to the conventional random operation.