• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.6
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• pp.453-460
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• 2008

This paper proposes a new multi-output LLC resonant converter by using single control IC, which has the tight-regulated dual output voltage without additional power devices and controller. The proposed converter has master and slave outputs, of which regulations are achieved by the PWM(pulse width modulation) and PFM(pulse frequency modulation), respectively. Different from the conventional dual-output LLC resonant converter, the proposed converter has no additional post-regulators like a boost converter. Therefore, it features a low cost, small size, and high efficiency. To confirm the validity and prove the superiority of proposed converter, simulated and experimental results on a 50" FHD PDP power set prototype are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2979-2984
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• 2013

This paper proposes a modeling and controller design method of Flywheel Energy Storage System(FESS) for solving the unstable operation problem in hybrid generation system with wind turbine and diesel generator applied in island area. FESS is considered as a permanent magnetic synchronous machine connected to flywheel because of its efficiency. The controller of FESS is composed of AC/DC/AC back-to-back converter. The AC/DC converter is designed to charge/discharge according to the frequency variation and the DC/AC converter to operate to keep the DC bus voltage constant. The proposed modeling and controller design method of FESS was applied to hybrid generation system with wind turbine and diesel generator. The unstable operation problem owing to wind variations was solved through simulation results.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.189-193
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• 2015

This paper provides the design techniques of a successive approximation register (SAR) type 12b analog-to-digital converter (ADC) for distributed maximum power point tracking (DMPPT) control in a photovoltaic system. Both a top-plate sampling technique and a $V_{CM}$-based switching technique are applied to the 12b capacitor digital-to-analog converter (CDAC). With these techniques, we can implement a 12b SAR ADC with a 10b capacitor array digital-to-analog converter (DAC). To enhance the accuracy of the ADC, a single-to-differential converted DAC is exploited with the dual sampling technique during top-plate sampling. Simulation results show that the proposed ADC can achieve a signal-to-noise plus distortion ratio (SNDR) of 70.8dB, a spurious free dynamic range (SFDR) of 83.3dB and an effective number of bits (ENOB) of 11.5b with bipolar CMOS LDMOD (BCDMOS) $0.35{\mu}m$ technology. Total power consumption is 115uW under a supply voltage of 3.3V at a sampling frequency of 1.25MHz. And the figure of merit (FoM) is 32.68fJ/conversion-step.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.12
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• pp.541-554
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• 1986

This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

• Journal of IKEEE
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• v.16 no.4
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• pp.335-342
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• 2012

This paper is studied on a new DCM-ZVS step up-down AC-DC converter of high performance, that is, high system efficiency and power factor correction (PFC). The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit uses a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuits and reduces the number of control components. The input AC current waveform in the proposed converter becomes a quasi-sinusoidal waveform proportional to the magnitude of input AC voltage under constant switching frequency. As a result, the proposed converter obtains low switching power loss and high efficiency, and its input power factor is nearly in unity. The validity of the analytical findings is confirmed by some computer simulation results and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.539-546
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• 1999

A new integrated single-stage zero current switched(ZCS) quasi resonant convertedQRC) for the IX)wer f factor correction(PFCl converter is introduced in this paper. The power factor correction can be achieved by t the discontinuous conduction mod$\varepsilon$(DCM) operation of an input current. The proposed converter has the c characteristics of the good IX)wer factor, 10씨 line current harmonics, and tight output regulation. Furthern10re, t the ringing effect due to the output capacitance of the main switch can be eliminated by use of‘ active clamp c circuit. Therefore, the proIX)sed converter is expecttc'(] to be suitable for a compact power converter with a t tightly regulated output voltage requiring a switching frequency of more than several hundrtc'(]s kHz.

• Smart Structures and Systems
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• v.18 no.3
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• pp.449-470
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• 2016

Energy harvesting is an emerging technique that extracts energy from surrounding environments to power low-power devices. For example, it can potentially provide sustainable energy for wireless sensing networks (WSNs) or structural control systems in civil engineering applications. This paper presents a comprehensive study on harvesting energy from earthquake-induced structural vibrations, which is typically of low frequency, to power WSNs. A macroscale pendulum-type electromagnetic harvester (MPEH) is proposed, analyzed and experimentally validated. The presented predictive model describes output power dependence with mass, efficiency and the power spectral density of base acceleration, providing a simple tool to estimate harvested energy. A series of shaking table tests in which a single-storey steel frame model equipped with a MPEH has been carried out under earthquake excitations. Three types of energy harvesting circuits, namely, a resistor circuit, a standard energy harvesting circuit (SEHC) and a voltage-mode controlled buck-boost converter were used for comparative study. In ideal cases, i.e., resistor circuit cases, the maximum electric energy of 8.72 J was harvested with the efficiency of 35.3%. In practical cases, the maximum electric energy of 4.67 J was extracted via the buck-boost converter under the same conditions. The predictive model on output power and harvested energy has been validated by the test data.

• Journal of Power Electronics
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• v.10 no.6
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• pp.777-783
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• 2010

In order to drive gas discharge lamps, DC-AC converters with a LCC resonant tank, whose output voltage is adjusted by a variable frequency control are frequently used. However, when they are activated by varying the operating frequency, converters are frequently damaged by unstable operation, due to the rising and falling of the operating frequency near the resonant frequency. To solve this problem, a simple protection circuit for the power supply of a gas discharge lamp is proposed in this paper. This circuit senses the primary current of the main transformer. Using this protection circuit, the operating frequency of the lamp driving inverter system is kept close to and on the right side of the resonant frequency and the inverter is always operated in the ZVS condition. The resulting stable variable frequency operation allows various gas discharge lamps to be tested without the risk of damaging the main switches, because the protection circuit can protect the power MOSFETs of bridge converters from abnormal conditions. The validity and effectiveness of the proposed protection circuit are verified through the experimental results.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.183-188
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• 2015

A 10-bit 10MS/s low power consumption successive approximation register (SAR) analog-to-digital converter (ADC) using a straightforward capacitive digital-to-analog converter (DAC) is presented in this paper. In the proposed capacitive DAC, switching is always straightforward, and its value is half of the peak-to-peak voltage in each step. Also the most significant bit (MSB) is decided without any switching power consumption. The application of the straightforward switching causes lower power consumption in the structure. The input is sampled at the bottom plate of the capacitor digital-to-analog converter (CDAC) as it provides better linearity and a higher effective number of bits. The comparator applies adaptive power control, which reduces the overall power consumption. The differential prototype SAR ADC was implemented with $0.18{\mu}m$ complementary metal-oxide semiconductor (CMOS) technology and achieves an effective number of bits (ENOB) of 9.49 at a sampling frequency of 10MS/s. The structure consumes 0.522mW from a 1.8V supply. Signal to noise-plus-distortion ratio (SNDR) and spurious free dynamic range (SFDR) are 59.5 dB and 67.1 dB and the figure of merit (FOM) is 95 fJ/conversion-step.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.45-53
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• 2013

Fuel cell power system is one of the most promising energy source for the alternative energy because it has unique advantages such as high energy density, no power drop during operation, and feasible to make compact size. However, due to very low response time, fuel cell is difficult to correspond to drastic load changes and start-up operation. For solving these problem, fuel cell power system must include energy storage device such as Li-Poly battery or super capacitor. Therefore, bi-directional DC-DC converter must be required for this storage device and fuel cell-PCS control. This paper presents a design and modeling of the bi-directional DC/DC converter. Firstly, we present modeling the boost and buck mode of the bi-directional converter through both PWM switch model and state space averaging technique. Secondly, in order to minimize output ripple and transient response overshoot, we have two identical DC-DC converters interleaved and adopt two-loop voltage-current controller. The proposed bi-directional DC-DC converter's modeling method and control design have been verified with computer simulation and experimentation.