• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1569-1576
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• 2014

This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge $120^{\circ}$ conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.

• Journal of Power Electronics
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• v.11 no.3
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• pp.375-380
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• 2011

A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using Gate Turn Off (GTO) power semiconductor devices employed for reactive power control. The operation principal is similar to that of a synchronous condenser. A typical application of a STATCOM is voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. This paper presents the modeling of STATCOM with twenty four pulse three level VSC and Type-1 controller to regulate the reactive current or the bus voltage. The performance is evaluated by transient simulation. It is observed that, the STATCOM shows excellent transient response to step change in the reactive current reference. While the eigenvalue analysis is based on D-Q model, the transient simulation is based on both D-Q and 3 phase models of STATCOM (which considers switching action of VSC).

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.797-799
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• 1993

In this paper, we propose a new PWM control method of cycloconverter with a resonant circuit for induction heating. The proposed new PWM control method determines the switching duty ratio compared the integrated value of load current with the reference value of input current on sampling interval. By the Proposed method, the displacement factor becomes 1.0 and the input current waveforms become sinusoid which is nearly 1.0 in terms of the input power factor. To confirm the validity of the proposed method, the simulations and experiments are carried out.

• Journal of Power Electronics
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• v.19 no.3
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• pp.613-624
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• 2019

Digital current control techniques are an attractive option for DC-DC converters. In this paper, a digital predictive peak current control algorithm is presented for buck converters that allows the inductor current to track the reference current in two switching cycles. This control algorithm predicts the inductor current in a future period by sampling the input voltage, output voltage and inductor current of the current period, which overcomes the problem of hardware periodic delay. Under the premise of ensuring the stability of the system, the response speed is greatly improved. A real-time parameter identification method is also proposed to obtain the precision coefficient of the control algorithm when the inductance is changed. The combination of the two algorithms achieves adaptive tracking of the peak inductor current. The performance of the proposed algorithms is verified using simulations and experimental results. In addition, its performance is compared with that of a conventional proportional-integral (PI) algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.2
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• pp.120-126
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• 2019

This study proposes a neutral voltage balance control scheme for stable fault-tolerant operation of an active neutral point clamped (ANPC) inverter using carrier-based pulse width modulation. The proposed scheme maintains the neutral voltage balance by reconfiguring the switching combination and modulating the reference output voltage in order to solve the degradation of the output characteristic in the fault tolerant operation due to the fault of the power semiconductor switch constituting the ANPC inverter. The feasibility of the proposed control scheme is confirmed by HIL experiment using RT-BOX.

• Journal of IKEEE
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• v.12 no.3
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• pp.176-183
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• 2008

The high efficiency power management IC(PMIC) with DTMOS(Dynamic Threshold voltage MOSFET) switching device is proposed in this paper. PMIC is controlled with PWM control method in order to have high power efficiency at high current level. DTMOS with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuits consist of a saw-tooth generator, a band-gap reference circuit, an error amplifier and a comparator circuit as a block. The Saw-tooth generator is made to have 1.2 MHz oscillation frequency and full range of output swing from ground to supply voltage(VDD:3.3V). The comparator is designed with two stage OP amplifier. And the error amplifier has 70dB DC gain and $64^{\circ}$ phase margin. DC-DC converter, based on Voltage-mode PWM control circuits and low on-resistance switching device, achieved the high efficiency near 95% at 100mA output current. And DC-DC converter is designed with LDO in stand-by mode which fewer than 1mA for high efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.486-495
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• 2006

In this paper, a low-power 1Kb synchronous EEPROM is designed with flash cells for passive UHF RFID tag chips. To make a low-power EEPROM, four techniques are newly proposed. Firstly, dual power supply voltages VDD(1.5V) and VDDP(2.5V), are used. Secondly, CKE signal is used to remove switching current due to clocking of synchronous circuits. Thirdly, a low-speed but low-power sensing scheme using clocked inverters is used instead of the conventional current sensing method. Lastly, the low-voltage, VDD for the reference voltage generator is supplied by using the Voltage-up converter in write cycle. An EEPROM is fabricated with the $0.25{\mu}m$ EEPROM process. Simulation results show that power dissipations are $4.25{\mu}W$ in the read cycle and $25{\mu}W$ in the write cycle, respectively. The layout area is $646.3\times657.68{\mu}m^2$.

• Biomolecules & Therapeutics
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• v.9 no.4
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• pp.291-297
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• 2001

The bioequivalence of two triflusal products was evaluated with 20 healthy volunteers following single oral dose according to the guidelines of Korea Food and Drug Administration (KFDA). Trisa $l^{R}$ capsule (Whanin Pharm. Corp., Korea) and Disgre $n^{R}$ capsule (Myung-In Pharm. Corp., Korea) were used as test product and reference product, respectively. Both products contain 300 mg of trifusal. One capsule of test product or reference product was orally administered to the volunteers, respectively, by randomized two period crossover study (2$\times$2 Latin square method). Blood samples were taken at predetermined time intervals for 4 hours and the determination of trifusal was accomplished using semi-microbore HPLC equipped with automated column switching system. The analytical method with HPLC was validated according to the Bioanalytic Method Validation guideline by F7A prior to determining the plasma samples. The pharmacokinetic parameters (AU $C_{0-4h}$ $C_{max}$ and $T_{max}$) were calculated and ANOVA test was utilized for statistical analysis of parameters. As a result of the assay validation, the limit of quantification of trifusal in human plasma by current assay procedure was 50 ng/ml using 500 $\mu$l of plasma. The accuracy of the assay was from 97.76% to 116.51% while the intra-day and inter-day coefficient of variation of the same concentration range was less than 15%. Average drug concentration at the designated time intervals and pharmacokinetic parameters calculated were not significantly different between two products (p>0.05). The difference of mean AU $C_{olongrightarrow4hr}$, $C_{max}$, and $T_{max}$ between the two products (2.92, 4.39, and -2.44%, respectively) were less than 20%. The power (1-$\beta$) and treatment difference ($\Delta$) for AU $C_{olongrightarrow4hr}$ and $C_{max}$ were more than 0.8 and less than 0.2, respectively. Although the power for $T_{max}$ was under 0.8, $T_{max}$ of the two products was not significantly different from each other (p>0.05). These results satisfied the criteria of KFDA guideline for bioequivalence, indicating the two products of triflusal were bioequivalent.quivalent.ent.ent.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.462-473
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• 1999

This paper addresses the current measurement issue of all digital field oriented control of ac motors. The p paper focuses on the effect of low-pass filter and also on the sampling of the fundamental component of the m motor current. The low-pass filter, which suppresses the switching noise of the motor current, introduces v variable phase delay according to the current ripple frequency. It is shown that the current sampling error c consists of the fundamental component and high frL'quency ripple components. In this paper, the dependency of t this current sampling e$\pi$or on the reference voltage vector is investigated analytically and a sampling technique i is proposed to minimize the error. The work is based on the three phase symmetry pulse width modulation l inverter driving an induction machine. With this technique, the bandwidth of current regulator can be extended t to the limit given by the switching frequency of the inverter and more precise torque regulation is possible.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.71-76
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• 2015

In this paper, we developed the hardware GPS signal generator for generating a satellite navigation signal synchronized with Live GPS signal signals and analyzed the performance of signal genterator thorough the experiment For a hardware implementation of the GPS navigation signal synchronous generator, the GPS module may receive a GPS signal in order to generate the same signal as the operation that is transmitted from the current GPS satellite and the synchronized time information and the GPS satellites using the Novatel Inc. OEMStar.In. For generating the GPS synchronization signal, the GPS navigation signal generator was adjusted to a reference clock using the GPS clock synchronous information provided by the GPS receiving module and GPS signals also generated in consideration of the delay of the internal hardware of the generator. In this paper, we analyzed the effect of the receiver via the signal switching between Live GPS signal and generates a signal to measure the performance of the GPS navigation synchronization signal generator. It was confirmed that by the seamless operation of the signal even the moment that the switching of the generated signal from Live GPS signal has occurred through experimentation.