• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1332-1342
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• 2014

This paper proposes a novel test circuit for SiC transistors. On-state resistance under practical application conditions is an important characteristic for the device reliability and conduction efficiency of SiC transistors. In order to measure the on-state resistance in practical applications, high voltage is needed, and high current is also necessary to ignite performance for the devices. A soft-switching circuit based on synchronous buck topology is developed in this paper. To provide high-voltage and high-current stresses for the devices without additional spikes and oscillations, a resonant circuit has been introduced. Using the novel circuit technology, soft-switching can be successfully realized for all the switches. Furthermore, in order to achieve accurate measurement of on-state resistance under switching operations, an active clamp circuit is employed. Operation principle and design analysis of the circuit are discussed. The dynamic measurement method is illustrated in detail. Simulation and experiments were carried out to verify the feasibility of the circuit. A special test circuit has been developed and built. Experimental results confirm that the proposed circuit gives a good insight of the devices performance in real applications.

• Journal of Power Electronics
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• v.16 no.1
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• pp.362-373
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• 2016

The on-line measurement of high-power IGBT collector current is important for the hierarchical control and short-circuit and overcurrent protection of its driver and the sensorless control of the converter. The conventional on-line measurement methods for IGBT collector current are not suitable for engineering measurement due to their large-size, high-cost, low-efficiency sensors, current transformers or dividers, etc. Based on the gate driver, this paper has proposed a current measuring circuit for IGBT collector current. The circuit is used to conduct non-intervention on-line measurement of IGBT collector current by detecting the voltage drop of the IGBT power emitter and the auxiliary emitter terminals. A theoretical analysis verifies the feasibility of this circuit. The circuit adopts an operational amplifier for impedance isolation to prevent the measuring circuit from affecting the dynamic performance of the IGBT. Due to using the scheme for integration first and amplification afterwards, the difficult problem of achieving high accuracy in the transient-state and on-state measurement of the voltage between the terminals of IGBT power emitter and the auxiliary emitter (u_Ee) has been solved. This is impossible for a conventional detector. On this basis, the adoption of a two-stage operational amplifier can better meet the requirements of high bandwidth measurement under the conditions of a small signal with a large gain. Finally, various experiments have been carried out under the conditions of several typical loads (resistance-inductance load, resistance load and inductance load), different IGBT junction temperatures, soft short-circuits and hard short-circuits for the on-line measurement of IGBT collector current. This is aided by the capacitor voltage which is the integration result of the voltage uEe. The results show that the proposed method of measuring IGBT collector current is feasible and effective.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.2
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• pp.126-131
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• 2015

When a battery is discharging, the battery's current and terminal voltage must both be measured to estimate its state of charge (SOC). If the SOC can be estimated by using only the current or voltage, hardware costs will decrease. This paper proposes an SOC estimation algorithm that needs to measure only the terminal voltage while a battery is discharging. The battery's SOC can be deduced from its open circuit voltage (OCV) through the relationship between SOC and OCV. But when the battery is discharging, it is not possible to measure the OCV due to the voltage drop in the battery's internal resistance (IRdrop). The proposed algorithm calculates OCV by estimating IRdrop using a dynamic terminal voltage measurement. This paper confirms the results of applying the algorithm in a hardware environment via algorithm binarization. To evaluate the algorithm, a Simulink battery model based on actual values was used.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.88.5-88
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• 2002

A new floating power supply for the current measurement system of a high voltage power line is developed. It is confirmed that, the current measurement system can stably transfer the signal of the power line current about 50 - 300 A by using the proposed power supply. The excellent characteristics are obtained by the steady-state and transient experiments of the proposed circuit. $\textbullet$ The right figure shows the external view of the trial measurement system for 6.6 kV. In order to see the inside, 120 degrees of the insulator is cut. The toroidal coil for the power supply and the Rogowskii coil for the current sensor are both divided into two and fixed on the power line as...$\textbullet$ The proposed circuit can supply +5V and -5V voltages without using a solar cell and/or a battery.

• Journal of Power Electronics
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• v.12 no.1
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• pp.208-214
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• 2012

This paper presents a novel approach based on the loci of instantaneous symmetrical components called "Wing Shape" which requires the measurement of three input stator currents and voltages to diagnose interturn insulation faults in three phase induction motors operating under different loading conditions. In this methodology, the effect of unbalanced supply conditions, constructional imbalances and measurement errors are also investigated. The sizes of the wings determine the loading on the motor and the travel of the wings while their areas determine the degree of severity of the faults. This approach is also applied to detect open circuit faults or single phasing conditions in induction motors. In order to validate this method, experimental results are presented for a 5 hp squirrel cage induction motor. The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant. It also allows maintenance to be performed in a more efficient manner, since the course of action can be determined based on the type and severity of the fault.

• Journal of Power Electronics
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• v.16 no.2
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• pp.786-797
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• 2016

This paper describes the design and development of a novel semiconductor-based solid-state switch for damped oscillating voltage test system. The proposed switch is configured as two identical series-connected switch stacks, each of which comprising 10 series-connected IGBT function units. Each unit consists of one IGBT, a gate driver, and an auxiliary voltage sharing circuit. A single switch stack can block 20 kV-rated high voltage, and two stacks in series are proven applicable to 30 kV-rated high voltage. The turn-on speed of the switch is approximately 250 ns. A flyback topology-based power supply system with a front-end power factor correction is built for the drive circuit by loosely inductively coupling each unit with a ferrite core to the primary side of a power generator to obtain the advantages of galvanic isolation and compact size. After the simulation, measurement, and estimation of the parasitic effect on the gate driver, a prototype is assembled and tested under different operating regimes. Experimental results are presented to demonstrate the performance of the developed prototype.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.5
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• pp.853-863
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• 2020

As the battery ages, the internal resistance of the battery increases, so the loss due to the internal resistance increases at the same charging current, causing the battery temperature to rise, which further accelerates battery aging. Therefore, it is necessary to optimize the charging conditions according to the aging of the battery or the current charge amount, and to accurately estimate this, estimation of the parameters of the equivalent circuit is most important. This paper proposes a new measurement technique that can measure the internal resistance of a battery by analyzing a specific high frequency voltage and current applied to the battery. In addition, in order to test the validity of the proposed measurement technique, the current charging amount was estimated based on the measured internal resistance, and the terminal voltage of the constant current charging mode was automatically set and operated. As a result, good results were obtained regardless of the battery voltage. If this equipment is installed in the charging device, it is believed that it will be of great help in the stability management of the aging reusable battery.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.346.2-346.2
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• 2016

The rear side contact recombination in the crystalline silicon solar cell could be reduced by back surface field. We formed polycrystalline silicon as a back surface field through crystallization of amorphous silicon. A thin silicon oxide applied to the passivation layer. We used quasi-steady-state photoconductance measurement to analyze electrical properties with various annealing condition. And, blister formed on surface of wafer during the annealing process. We observed the blister after varied annealing process with wafer of various surface. Shape and density of blister is influenced by various annealing temperature and process time. As the annealing temperature became higher, the average diameter of blister is decreased and total number of blister is increased. The sample with the $600^{\circ}C$ annealing temperature and 1 min annealing time exhibited the highest implied open circuit voltage and lifetime. We predicted that the various shape and density of blister affects the lifetime and implied open circuit voltage.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.272-275
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• 2014

An improved fuzzy Kalman filtering speed estimation scheme was proposed by means of measuring stator side voltage and current value based on vector control state equation of induction motor. The designed fuzzy adaptive controller conducted recursive online correction of measurement noise covariance matrix by monitoring the ratio of theory residuals and actual residuals to make it approach real noise level gradually, allowing the filter to perform optimal estimation to improve estimation accuracy of EKF. Meanwhile, co-simulation scheme based on MATLAB and Ansoft was proposed in order to improve simulation accuracy. Field-circuit coupling problems of induction motor under the action of vector control were solved and the parameter optimization accuracy was improved dramatically. The simulation and experimental results show that this algorithm has a strong ability to inhibit the random measurement noise. It is able to estimate motor speed accurately, and has superior static and dynamic characteristics.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.3
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• pp.55-62
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• 2000

This paper presents an analysis of the chaotic behavior in the discrete-time voltage mode chaotic generator fabricated using 0.8${\mu}{\textrm}{m}$ single poly CMOS technology. An approximated empirical equation is extracted from the measurement data of a nonlinear function block. Then the bifurcation diagram is simulated according to input variables and Lyapunov exponent λ which represent a dependence on an initial value is calculated. We show the interrelations among time waveforms, state transition, and power spectra for the state condition of chaotic circuit, such as equilibrium, periodic, and chaotic state. And results of experiments in the chaotic circuit with the $\pm$2.5V power supply and sampling clock frequency of 10KHz are shown and compared with the simulated results.