• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.133-135
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• 2004

As a result of the recent advances in magnetic materials, the Magnetic Amplifier(Magamp) technique is one of the reliable and cost-effective postregulation method for multiple-output power supply. This is true for high-current postregulated output since at highter output current the efficiency of linear postregulation is unacceptably low, while the complexity of more efficient switch mode postregulator is associated with a significant cost. Magamp have some advantages of higher power density, simple control circuit, good regulation, high frequency and high performance. In this paper, Operation principle of proposed approach and a performance of magamp control circuit with TL431 is described. The comparative analysis of magamp circuit and buck regulator circuit with 20W load condition is conducted. Experimental verifications on multi-output flyback converter are conducted. Simulations and experimental results show that the proposed approach is efficiency and voltage regulation of the auxiliary output is excellent.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1050-1051
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• 2015

In industry, there are several different controllers which can be implemented for power conditioning systems (PCS) such as proportional-resonant (PR), predictive deadbeat (PD), or proportional-integral (PI) controller. But there are not any comparison studies about these controllers. To investigate the differences between the three types of the controllers, this paper presents a comparative study of PR, PI, and PD controllers in a photovoltaic (PV) PCS. These controllers are designed mathematically and simulated for the comparative analysis. The PI controller is designed in the rotating reference (dq) frame. The PR and PD controllers are implemented in the natural (abc) reference frame. The PCS is composed of a DC-DC boost converter and a full bridge inverter. The filter of the PCS is an LCL filter including a passive damping resistor. The parameters of PCS are 3 kW, 25 kHz switching frequency and 220 V-60 Hz grid voltage. The comparison results between these controllers for the grid-connected PCS are clearly shown. The simulation results demonstrate the detailed characteristics of each controller for the PV PCS in order to choose the controller for individual target properly.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.74-80
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• 2006

This paper describes a solar energy conversion strategy is applied to grid-connected single phase inverter by the maximum power point of conversion strategy. The maximum power point of tracking is controlled output power of PV(photovoltaic)modules, based on generated circuit control MOSFET switch of two boost converter for a connected single phase inverter with four IGBT's switch in full bridge. The generation control circuit allows each photovoltaic module to operate independently at peak capacity, simply by detecting of the output power of PV module. Furthermore, the generation control circuit attenuates low-frequency ripple voltage. which is caused by the full-bridge inverter, across the photovoltaic modules. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation.

• ETRI Journal
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• v.31 no.6
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• pp.717-724
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• 2009

This paper describes a 1.2 V 12 b 60 MS/s CMOS analog front-end (AFE) employing low-power and flexible design techniques for image signal processing. An op-amp preset technique and programmable capacitor array scheme are used in a variable gain amplifier to reduce the power consumption with a small area of the AFE. A pipelined analog-to-digital converter with variable resolution and a clock detector provide operation flexibility with regard to resolution and speed. The AFE is fabricated in a 0.13 ${\mu}m$ CMOS process and shows a gain error of 0.68 LSB with 0.0352 dB gain steps and a differential/integral nonlinearity of 0.64/1.58 LSB. The signal-to-noise ratio of the AFE is 59.7 dB at a 60 MHz sampling frequency. The AFE occupies 1.73 $mm^2$ and dissipates 64 mW from a 1.2 V supply. Also, the performance of the proposed AFE is demonstrated by an implementation of an image signal processing platform for digital camcorders.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.179-187
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• 2010

This paper proposes a new anti-islanding method for single-phase grid-connected photovoltaic (PV) systems using Goertzel algorithm. The proposed scheme is based on inducing increases or decreases of frequencies of load voltage and current that is in the form of existences or periodical variations of the reactive power components. The frequency detection is needed to apply this power variation method to the grid-connected power converter. The proposed method is able to get a fast detection for anti-islanding without the effect of harmonics and noises. The simulation and experiment results validate the effectiveness of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.543-552
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• 1996

The goal of this paper is to developed a DSP based power analyzing and control system by 3-Dimensional (3-D) space current co-ordinates. A developed system is made up of 486-PC and DSP (Digital Signal Processor) board, Active Power Filter, Non-linear thyristor load, and Power analyzing and control program for Windows. Power is analyzed using signal processing techniques based on the correlation between voltage and current waveforms. Since power analysis algorithm is performed by DSP, power analysis is achieved in real-time even under highly dynamic nonlinear loading conditions. Combining control algorithm with power analysis algorithm is performed by DSP, power analysis is achieved in real-time even under highly dynamic nonlinear loading conditions. Combining control algorithm with power analysis algorithm, flexibility of the proposed system which has both power analysis mode and control mode, is greatly enhanced. Non-active power generated while speed of induction motor is controlled by modulating firing angle of thyristor converter, is compensated by Active Power Filter for verifying a developed system. Power analysis results, before/after compensation, are numerically obtained and evaluated. From these results, various graphic screens for time/frequency/3-D current co-ordinate system are displayed on PC. By real-time analysis of power using a developed system, power quality is evaluated, and compared with that of conventional current co-ordinate system. (author). refs., figs. tabs.

• Journal of Power Electronics
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• v.16 no.1
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• pp.111-120
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• 2016

Generally, a single phase H-bridge converter feeding a single primary track is employed in conventional inductive power transfer systems. However, these systems may not be suitable for some high power applications due to the constraints of the semiconductor switches and the cost. To resolve this problem, a novel dual coupled primary tracks IPT system consisting of two high frequency resonant inverters feeding the tracks is presented in this paper. The primary tracks are wound around an E-shape ferrite core in parallel which enhances the magnetic flux around the tracks. The mutual inductance of the coupled tracks is utilized to achieve adjustable power sharing between the inverters by configuring the additional resonant capacitors. The total transfer power can be continuously regulated by altering the pulse width of the inverters' output voltage with the phase shift control approach. In addition, the system's efficiency and the control strategy are provided to analyze the characteristic of the proposed IPT system. An experimental setup with total power of 1.4kW is employed to verify the proposed system under power ratios of 1:1 and 1:2 with a transfer efficiency up to 88.7%. The results verify the performance of the proposed system.

• Journal of Power Electronics
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• v.11 no.3
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• pp.311-318
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• 2011

LCL filters installed at converter outputs offer a higher harmonic attenuation than L filters. However, as a three order resonant circuit, it is difficult to stabilize and has a risk of oscillating with the power grid. Therefore, careful design is required to damp LCL resonance. Compared to a passive damping method, an active damping method is a more attractive solution for this problem, since it avoids extra power losses. In this paper, the damping capabilities of capacitor current, capacitor voltage, and grid-side current feedback methods, are analyzed under the discrete-time state-space model. Theoretical analysis shows that the grid-side current feedback method is more suitable for use in active power filters, because it can damp LCL resonance more effectively than the other two methods when the ratio of the resonance and the control frequency is between 0.225 and 0.325. Furthermore, since there is no need for extra sensors for additional states measurements, this method provides a cost-efficient solution. To support the theoretical analysis, the proposed method is tested on a 7-kVA single-phase shunt active power filter.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.1-6
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• 2007

Wireless Self-Powered Temperature Sensor for UHF Sensor Tags which are basic device for construction of ubiquitous sensor network is proposed. The key parameters of the target specification are resolution of $0.1\;^{\circ}C$ per output bit, below 1.5 V of operating voltage and below 5 uW of power consumption during sensing operation. Temperature sensor circuit consists of PTAT current generator, band gap reference circuit generating both reference voltage and current, Sigma-Delta Converter, and Digital Counter. Simulated maximum resolution was $0.23\;^{\circ}C/bit$ in 11-bit output. The proposed temperature sensor was fabricated by using a 0.25 m CMOS process. The chip area is $0.32\;{\times}\;0.22\;mm$ and the operating frequency is 2 MHz. Measured resolution from fabricated temperature sensor was $4\;^{\circ}C/bit$ in 8-bit output for the temperature range from $10^{\circ}C$ to $80^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.504-510
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• 2017

This paper presents an AC-DC power module design and evaluates its efficiency and reliability when used for electronics appliances. This power module consists of a PWM control IC, power MOSFETs, a transformer and several passive devices. The module was tested at an input voltage of 220V (RMS) (frequency 60 Hz). A test was conducted in order to evaluate the operation and power efficiency of the module, as well as the reliability of its protection functions, such as its over-current protection (OVP), overvoltage protection (OVP) and electromagnetic interference (EMI) properties. Especially, we evaluated the thermal shut-down protection (TSP) function in order to assure the operation of the module under high temperature conditions. The efficiency and reliability measurement results showed that at an output voltage of 5 V, the module had a ripple voltage of 200 mV, power efficiency of 73 % and maximum temperature of $80^{\circ}C$ and it had the ability to withstand a stimulus of high input voltage of 4.2 kV during 60 seconds.