• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.342-348
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• 2021

The PV module of solar power systems requires maximum power point tracking (MPPT) technique because the power-voltage and current-voltage characteristics vary depending on the surrounding environment. In addition, the 120 Hz ripple voltage on the DC-Link is caused by the imbalance of the system voltage and current. The effect of this 120 Hz ripple voltage reduces the efficiency of the power generation system by increasing the output current distortion rate. Increasing the capacity of DC-Link can reduce the 120 Hz ripple voltage, but this method is inefficient in price and size. We propose a technique that detects 120 Hz ripple voltage and reduces the effect of ripple voltage without increasing the DC-Link capacity through a controller. The proposed technique was verified through simulations and experiments using a 1 kW single-phase solar power system. In addition, the proposed technique's feasibility was demonstrated by reducing the distortion rate of the output current.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.376-378
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• 1996

This paper presents a new PFC control method which replaces a fast line current measurement with a filtered load current measurement. Using the power balance relation between the input and the output of the boost converter. the input current can be described as the function of load current. Thus the PWM signal which effects the switching control of the boost converter is generated using the PFC input voltage, the PFC output voltage and the load current as input variables. By using a filter between the bridge rectifier and a dc-to-dc converter, the input voltage of the dc-to-dc converter is forced to always maintain above zero volt. Then the input current traces a sinewave in phase. The proposed scheme accomplishes a very high power factor and a low harmonic distortion of the line current. The validity of this scheme is demonstrated through simulation.

• Journal of Power Electronics
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• v.12 no.4
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• pp.587-594
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• 2012

When a PWM rectifier has a low DC-link voltage during startup, the output voltage vector cannot be high enough to regulate the input current. This lack of a PWM rectifier output voltage vector can cause an unregulated inrush current when the rectifier operation starts. This paper presents a PWM rectifier start-up current control algorithm for when it starts operation with a lower DC-link voltage than unloaded condition case. To avoid the unregulated inrush current caused by a lack of DC-link voltage, the proposed control scheme regulates the one phase current with one switch chopping and it generates the current command considering the uncontrolled current magnitude information, which is calculated in advance. Simulation and experiment results support the validity of the proposed method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.472-475
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• 2002

A Rogowski coil can measure alternating currents from a few amps to over 1 million amps in a frequency range from less than 0.1 Hz to about lMhz. A Rogowski coil provides an induced output voltage which is proportional to the rate of change of the primary current enclosed by the flexible or the rigid coil-loop. Therefore, it is necessary to integrate the output voltage in order to produce a voltage proportional to the current. Also. it can reproduce the current waveform on an oscilloscope or any type of data acquisition device. This paper describes the practical design of the combination of a Rogowski coil and an integrator which provides a versatile current measuring system to accommodate a wide range of frequencies, current levels and conductor sizes.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.13-20
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• 2001

In this appear, we proposed the new current mirror has large output resistance and excellent current matching characteristics. If supply voltage were lowered under the conventional CMOS operational amplifier, the wing of out put power could be restricted. So, the paper suggests a new way of differential operational amplifier circuit to solve the problem. The paper proposes that a new current mirror increases output swing and has a stable operation. We compare and verify characteristics of the proposed current mirror with the cascoded current mirror and the regulated current mirror through simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.589-595
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• 2007

This paper presents a new method on controller design of brushless dc motors. In such drives the current ripples are generated by motor inductance in stator windings and the back EMF. To suppress the current ripples the current controller is generally used. To minimize the size and the cost of the drives it is desirable to control motors without the current controller and the current sensing circuits. To estimate the motor CUlTent it is modeled by a neural network that is contigured as an output-error dynamic system. The identified model is essentially a one step ahead prediction structure in which past inputs and outputs are used to calculate the current output. Using the model, a state feedback controller to compensate the effects of disturbance has been designed. The controller is implemented by a 16-bit microprocessor and the effectiveness of the proposed control method is verified through experiments.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.1
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• pp.44-49
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• 2003

This paper describes a percentage current differential relaying algorithm for bus protection blocked by a CT saturation detection algorithm. The detection algorithm blocks the output of a current differential relay only if a differential current is caused by CT saturation in the case of an external fault. Moreover, if a current differential relay operates faster than the detection algorithm, the blocking signal is not ignited. On the other hand. if the detection algorithm operates faster than a current differential relay, the output of the relay is blocked. The results of the simulation show that the proposed algorithm can discriminate internal faults from external faults ever when a CT is saturated in both cases. This paper concludes by implementing the algorithm into the TMS320C6701 digital signal processor. The results of hardware implementation are also satisfactory The algorithm can not only increase the sensitivity of the current differential relay but Improve the stability of the relay for an external faults.

• Journal of IKEEE
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• v.23 no.1
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• pp.230-234
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• 2019

This paper shows the development of current sensor for the measurement of hundreds of nanoseconds large current in pulsed power and its characteristics evaluation. The developed current sensor was designed for measuring induced voltage from magnetic flux under the operation of pulsed power. Output characteristics of developed current sensor was good consistent with commercial one, and the realistic current of fast pulsed power was detected easily with the calibration curve using output voltage of developed sensor. Therefore, the developed current sensor is possible to apply the realistic system.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.203-204
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• 2014

In this paper, single-phase uninterruptible power supply design method is presented. In this control scheme, input current, output current and output voltage are used. For voltage control PR controller is used and that for current controller is PI controller. The gains for controllers are sought by the classical method for determining gains. Throughout simulations the performance of single-phase UPS is verified.

• Journal of information and communication convergence engineering
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• v.8 no.5
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• pp.566-569
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• 2010

This paper describes the sinusoidal, pulse, triangular oscillator using second generation current conveyor. To obtain the sinusoidal waveform the circuit blocks are constructed by using all pass filter and integrator. The pulse and the triangular waveforms are obtained from the output of sinusoidal oscillator. The peak-to-peak voltages of sinusoidal and triangular waveforms can be easily controlled by the dc offset voltage. Also the output frequency of the oscillator can be controlled by varying passive elements. The designed circuit is verified by HSPICE simulation.