• Title/Summary/Keyword: Single loop

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Control Strategies of Both the Heater Temperature and the Inverter Output Voltage of a Single-Phase PWM Inverter Systems for Heat Treatment (열처리용 단상 PWM인버터시스템의 히터온도 및 인버터 출력전압 제어기법)

  • Yang, Si-Gyeong;Chun, Tae-Won
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.8
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    • pp.1047-1054
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    • 2018
  • This paper proposed the strategies for controlling both the heater temperature and the output voltage of a single-phase inverter for the heat treatment. The single-phase inverter system for the heat treatment controls the heater temperature to its reference one, and also it limits the inverter output voltage to 60 V for safety. The stability may be deteriorated due to the large time constant difference between the heater temperature and inverter output voltage. In order to ensure the stability, a hysteresis on/off control approach for the heater temperature control is adapted, and both the open-loop and the closed-loop control strategies of the output voltage are suggested. The performances for the proposed strategies are demonstrated with the experiments.

Analysis of Phase Error Effects Due to Grid Frequency Variation of SRF-PLL Based on APF

  • Seong, Ui-Seok;Hwang, Seon-Hwan
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.18-26
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    • 2016
  • This paper proposes a compensation algorithm for reducing a specific ripple component on synchronous reference frame phase locked loop (SRF-PLL) in grid-tied single-phase inverters. In general, SRF-PLL, which is based on all-pass filter to generate virtual voltage, is widely used to estimate the grid phase angle in a single-phase system. In reality, the estimated grid phase angle might be distorted because the phase difference between actual and virtual voltages is not 90 degrees. That is, the phase error is caused by the difference between cut-off frequency of all-pass filter and grid frequency under grid frequency variation. Therefore, the effects on phase angle and output current attributed to the phase error are mathematically analyzed in this paper. In addition, the proportional resonant (PR) controller is adapted to reduce the effects of phase error. The validity of the proposed algorithm is verified through several simulations and experiments.

Advanced SOGI-FLL Scheme Based on Fuzzy Logic for Single-Phase Grid-Connected Converters

  • Park, Jin-Sang;Nguyen, Thanh Hai;Lee, Dong-Choon
    • Journal of Power Electronics
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    • v.14 no.3
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    • pp.598-607
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    • 2014
  • This paper proposes a frequency-locked loop (FLL) scheme for a single-phase grid-connected converter. A second-order generalized integrator (SOGI) based on fuzzy logic (FL) is applied to this converter to achieve precise phase angle detection. The use of this method enables the compensation of the nonlinear characteristic of the frequency error, which is defined in the SOGI scheme as the variation of the central frequency through the self-tuning gain. With the proposed scheme, the performance of the SOGI-FLL is further improved at the grid disturbances, which results in the stable operation of the grid converter under grid voltage sags or frequency variation. The PSIM simulation and experimental results are shown to verify the effectiveness of the proposed method.

Estimation of Individual Vehicle Speed Using Single Sensor Configurations (단일 센서(Single Sensor)를 활용한 차량속도 추정에 관한 연구)

  • Oh, Ju-Sam;Kim, Jong-Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3D
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    • pp.461-467
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    • 2006
  • To detect individual vehicular speed, double loop detection technique has been widely used. This paper investigates four methodologies to measure individual speed using only a single loop sensor in a traveling lane. Two methods developed earlier include estimating the speed by means of (Case 1) the slop of inductance wave form generated by the sensor and (Case 2) the average vehicle lengths. Two other methods are newly developed through this study, which are estimations by measuring (Case 3) the mean of wheelbases using the sensor installed traversal to the traveling lane and (Case 4) the mean of wheel tracks by the sensor installed diagonally to the traveling lane. These four methodologies were field-tested and their accuracy of speed output was compared statistically. This study used Equality Coefficient and Mean Absolute Percentage Error for the assessment. It was found that the method (Case 1) was best accurate, followed by method (Case 4), (Case 2), and (Case 3).

Single-Chip Controller Design for Piezoelectric Actuators using FPGA (FPGA를 이용한 압전소자 작동기용 단일칩 제어기 설계)

  • Yoon, Min-Ho;Park, Jungkeun;Kang, Taesam
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.7
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    • pp.513-518
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    • 2016
  • The piezoelectric actuating device is known for its large power density and simple structure. It can generate a larger force than a conventional actuator and has also wide bandwidth with fast response in a compact size. To control the piezoelectric actuator, we need an analog signal conditioning circuit as well as digital microcontrollers. Conventional microcontrollers are not equipped with an analog part and need digital-to-analog converters, which makes the system bulky compared with the small size of piezoelectric devices. To overcome these weaknesses, we are developing a single-chip controller that can handle analog and digital signals simultaneously using mixed-signal FPGA technology. This gives more flexibility than traditional fixed-function microcontrollers, and the control speed can be increased greatly due to the parallel processing characteristics of the FPGA. In this paper, we developed a floating-point multiplier, PWM generator, 80-kHz power control loop, and 1-kHz position feedback control loop using a single mixed-signal FPGA. It takes only 50 ns for single floating-point multiplication. The PWM generator gives two outputs to control the charging and discharging of the high-voltage output capacitor. Through experimentation and simulation, it is demonstrated that the designed control loops work properly in a real environment.

A Low-Power CMOS Continuous-Time Sigma-Delta Modulator for UMTS Receivers (UMTS용 수신기를 위한 저 전력 CMOS 연속-시간 시그마-델타 모듈레이터)

  • Lim, Jin-Up;Choi, Joong-Ho
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.44 no.8
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    • pp.65-73
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    • 2007
  • This paper presents a low power CMOS continuous-time $\Sigma\Delta$ (sigma-delta) modulator for UMTS receivers. The loop filter of the continuous-time $\Sigma\Delta$ modulator consists of an active-RC filter which performs high linearity characteristics and has a simple tuning circuit for low power operating system The architecture of this modulator is the $3^{rd}-order$ 4-bit single loop configuration with a 24 of OSR (Oversampling Ratio) to increase the power efficiency. The modulator includes a half delay feedback path to compensate the excess loop delay. The experimental results of the modulator are 71dB, 65dB and 74dB of the peak SNR, peak SMR and dynamic range, respectively. The continuous-time $\Sigma\Delta$ modulator is fabricated in a 0.18-um 1P4M CMOS standard process and dissipates 15mW for a single supply voltage of 1.8V.

Performance Evaluation of Large Borehole Ground-Loop Heat Exchanger (저심도 대구경 지중열교환기의 설치조건에 따른 성능 연구)

  • Yoo, Gyu-Sang;Park, Il-Mun;Choi, Jae-Ho;Shin, Hyun-Joon
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.58-63
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    • 2009
  • A ground-loop heat exchanger for the ground source heat pump system is the core equipment determining the thermal performance and initial cost of the system. The size and performance of the heat exchanger is highly dependent on the ground thermal properties - the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. Nowadays, precast concrete piles using steel reinforced precast concrete piles - energy piles - are used to reduce the installing cost of the ground-loop heat exchanger. We were carried out some tests to investigate the effects of some parameters such as borehole length, grouting materials and U-tube configuration of the energy piles. 4 concrete piles, each measuring $250mm{\sim}400mm$ in diameter and approx. 10m in length, and rigged with single spiral and 3 U-tube loop of $16mm{\times}2.3mm$ PB piping. The thermal response tests were conducted using a testing device for 4-different ground-loop heat exchangers. During the heating period, the energy piles absorb the heat of 0.89kW to 1.37kW.

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On the suboptimal $H_{2}$ Design for Improved Stability Margin (안정도 여유를 고려한 준최적 $H_{2}$ 설계 기법)

  • 박기헌
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.66-70
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    • 1991
  • A mixed $H_{2}$ / H.inf. design methodology is suggested for a single-input-single-output system. Suboptimal $H_{2 }$ controllers stabilizing the closed loop system under the additive uncertainty are obtained. An extended Nevanlinna-Pick algorithm is used to obtain the suboptimal. controllers.s.

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A Comparative Study for Reliability of Single and Radial Power Distribution System considering Momentary Interruption (단일루프 배전계통과 방사상 배전계통의 순간정전을 고려한 신뢰도 비교 연구)

  • Lee, Hee-Tae;Kim, Jae-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.7
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    • pp.1270-1275
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    • 2009
  • The structure of a power distribution system will change in a loop configuration such as in the case of a smart grid. If power distribution system changes radial to loop form, the structure may have to be changed significantly. Therefore, we analyzed the reliability indices and calculated a CIC(Customer Interruption Cost) for the loop power distribution system. The power distribution system reliability depends on the protection scheme. This study is applied to the current protection scheme method and is compared with each model. When the CIC was evaluated, most studies performed calculations only for sustained interruptions. However, in actuality, momentary interruption frequencies occurred more than sustain interruptions. Thus, it is occurred the CIC additively. Therefore, we evaluated a CIC including momentary interruption, for each model, and then compared with MAIFI(Momentary Average Interruption Frequency Index)

Dual Loop Optoelectronic Oscillator with Acousto-Optic Delay Line

  • Kim, Tae Hyun;Lee, Sangkyung;Lee, Chang Hwa;Yim, Sin Hyuk
    • Journal of the Optical Society of Korea
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    • v.20 no.2
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    • pp.300-304
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    • 2016
  • A dual loop optoelectronic oscillator (OEO) based on an acousto-optic modulator (AOM) for single mode operation with an acousto-optic delay line is demonstrated in this paper. When the OEO operates, the free spectral range is a function of the total loop length of the OEO, which is mainly dependent on the propagation time of the acoustic wave in the AOM. Due to the huge difference in the magnitude between the speed of light and the acoustic velocity in the AOM, the effective loop length converted to light-propagation length of the OEO increases to 3.8 km. With 150 MHz oscillation frequency, phase noise of -118 dBc/Hz at 10 kHz frequency offset, and -140 dBc/Hz at 200 kHz frequency offset, is achieved.