• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.67-74
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• 2018

The verification for the design limit margin of the power device for the information communication and surveillance systems using HALT(Highly Accelerated Life Test) reliability test is described. The HALT reliability test performs with a step stress method which change condition until the marginal step in a design and development phase. The HALT test methods are the low temperature(cold) step stress test, the high temperature(hot) step stress test, the thermal shock cyclic stess test, and the high temperature destruct limit(hot DL) step stress test. The power device is checked the operating performance during the test. In this paper, the HALT was performed to find out the design limit margin of the power device.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.330-335
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• 2012

Brushless doubly-fed machine (BDFM) doesn't use brush and slip ring, and has advantages such as high system reliability, small capacity of its frequency converter, low system cost, adjustable power factor and speed, etc. At the same time, it has good applicable potentials on the variable frequency motors and the variable speed constant frequency generators. However, due to the complicacy and particularity of BDFM in the structure and operating mechanism, the effect of magnetic field modulation directly influences the operating efficiency of BDFM. To study the effect of different cage rotor structures on the magnetic field modulation of BDFM, the rotor magnetomotive force (MMF) of BDFM with cage rotor is studied by the analytical method. The components and features of rotor harmonic MMFs are discussed. At the same time, the method to weaken the higher harmonics is analyzed by the theoretic formulae. Furthermore, the magnetic field modulation mechanism is expounded on in detail and the relationship between the magnetic field modulation effect and the operating efficiency of BDFM is established. And then, a new method for estimating the magnetic field modulation effect is proposed. At last, the magnetic field modulation effects of four BDFM prototypes with different cage rotor structures are compared by the MMF analysis and the efficiency data of electromagnetic design. The results verify the effectiveness of the new method for estimating the magnetic field modulation effect of BDFM with cage rotor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.120-126
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• 2009

This paper presents an optimal operating scheme by integrating Sihwa tidal power into NamSihwa systems. For optimal operation of NamSihwa systems, the sea levels of 1 minute interval using cubic interpolation based on the forecasted levels of high and low water are calculated. Especially, it is compared by three schemes to purchase total power from transmission system to purchase total power from tidal power system in time period that can generate tidal power and to purchase total power by comparing purchase costs from transmission system and tidal power system. The scheme may contribute to energy save in Korea that natural resources are lacking.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.226-228
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• 2007

SRM drive systems are designed to meet operating standards such as low cost, constant torque independent of rotor position, a desired operating speed range, high efficiency, and high performance. In applications using small motors, low cost and high performance with self-starting capabilities are highly desired. This paper discusses a novel two phase SRM (TPSRM) that has high performance characteristics with self-starting capability, low manufacturing cost with a two phase inverter and simple magnetic structure, and high efficiency. The principle of operation, analysis, and simulation for design are presented. The machine design is verified using finite element analysis (FEA) software. Analysis and simulation results are given to validate the TPSRM design.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.325-328
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• 2002

In this paper. we propose a floating resistor with positive and negative resistance operating at lower supply voltages. The circuit uses only two transistors between the supply voltages. which enable to operate it at low supply voltages. Moreover. the circuit uses fewer number of transistors compared to the reported work. The gate terminal is used in this circuit for the current addition/subraction at the terminals of resistor. The characteristic of the proposed circuit is verified using HSPICE for the power supply +/-1.5V.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.416-422
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• 2012

This paper proposes a low power-loss current measurement using a resistor and bypass switch. Conventional current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. The propose measurement works for discrete-time sampling of current sensing. Even while the analog-digital conversion does not occur at the controller, the sensing voltage across the sensor still causes ohmic conduction loss without information delivery. Hence, the bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 90[W] prototype hardware has been implemented for photovoltaic MPPT experimental verification of the proposed low power-loss current measurement technique. From the results, it can be seen that PV power observation is successfully done with the proposed method.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.231-237
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• 2016

Recently, the interest in DC systems to achieve more efficient connection with renewable energy sources, energy storage systems, and DC loads has been growing extensively. DC systems are more advantageous than AC systems because of their low conversion losses. However, the DC-link voltage is variable during operation because of different random effects. This study focuses on DC voltage stabilization applied in stand-alone DC microgrids by means of voltage ranges, power management, and coordination scheme. The quality and stability of the entire system are improved by keeping the voltage within acceptable limits. In terms of optimized control, the maximum power should be tracked from renewable resources during different operating modes of the system. The ESS and VSDG cover the power shortage after all available renewable energy is consumed. Keeping the state of charge of the ESS within the allowed bands is the key role of the control system. Load shedding or power generation curtailment should automatically occur if the maximum tolerable voltage variation is exceeded. PSIM-based simulation results are presented to evaluate the performance of the proposed control measures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.1047-1051
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• 2004

Charge amplifier systems benefit from the very wide dynamic range of PE accelerometers by offering flexibility in adjusting the electrical output characteristics such as sensitivity and range. They are well suited for operation at high temperatures. Modern charge systems feature improved low noise operation, simplified digital controls, and dual mode operation for operation with charge or IEPE voltage mode sensors. high impedance circuitry is not well suited for operation in adverse field or factory environments. The resolution of a PE accelerometer may not be specified or known since noise is a system consideration determined by cable length and amplifier gain. IEPE accelerometrs operate from a constant current power source, provide a high-voltage, low-impedance, fixed mV/g output. They operate through long, ordinary, coaxial cable in adverse environments without degradation of signal quality. They have limited high temperature range. IEPE sensors are simple to operate. Both resolution and operating range are defined specifications. Cost perchannel is lower compared to PE systems since low-noise cable and charge amplifiers are not required.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.321-324
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• 2001

This paper describes a fast and low-power multiplier co-processor architecture for digital signal processing applications and real-time control systems and its use as a multiplier co-processor for a 32-bit RISC microprocessor utilizing its one of the 16 co-processor interfaces. Its architecture adopts various algorithms to reduce the dynamic power and the area as well. The designed multiplier performs 32$\times$32 bit multiplication, and was designed using verilog HDL and 0.35${\mu}{\textrm}{m}$, 3V, 4M CMOS standard cell library. Its target operating speed is 40MHz, area lower than 10000 gate counts, and 10mW/MHz of power.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1402-1412
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• 2017

This paper presents a new high step-up dc/dc converter for renewable energy systems in which a high voltage gain is provided by using a coupled inductor. The operation of the proposed converter is based on a charging capacitor with a single power switch in its structure. A passive clamp circuit composed of capacitors and diodes is employed in the proposed converter for lowering the voltage stress on the power switch as well as increasing the voltage gain of the converter. Since the voltage stress is low in the provided topology, a switch with a small ON-state resistance can be used. As a result, the losses are decreased and the efficiency is increased. The operating principle and steady-states analyses are discussed in detail. To confirm the viability and accurate performance of the proposed high step-up dc-dc converter, several simulation and experimental results obtained through PSCAD/EMTDC software and a built prototype are provided.