• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1614-1622
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• 2014

A novel equivalent flux sliding-mode observer (SMO) is proposed for dual three-phase interior permanent magnet synchronous motor (DT-IPMSM) drive system in this paper. The DT-IPMSM has two sets of Y-connected stator three-phase windings spatially shifted by 30 electrical degrees. In this method, the sensorless drive system employs a flux SMO with soft phase-locked loop method for rotor speed and position estimation, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Meanwhile, to get the regulator parameters of current control, the inner current loop is realized using a decoupling and diagonal internal model control algorithm. Experiment results of 2MW-level DT-IPMSM drives system show that the proposed method has good dynamic and static performances.

• ETRI Journal
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• v.19 no.2
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• pp.35-47
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• 1997

A power amplifier operating at 3.3 V has been developed for CDMA/AMPS dual-mode cellular phones. It consists of linear GaAs power MESFET's, a new gate bias control circuit, and an output matching circuit which prevents the drain terminal of the second MESF from generating the harmonics. The relationship between the intermodulation distortion and the spectral regrowth of the power amplifier has been investigated with gate bias by using the two-tone test method and the adjacent channel leakage power ratio (ACPR) method of CDMA signals. The dissipation power of the power amplifier with a gate bias control circuit is minimized to below 1000 mW in the range of the low power levels while satisfying the ACPR of less than -26 dBc for CDMA mode. The ACPR of the power amplifier is measured to be -33 dBc at a high output power of 26 dBm.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.40-47
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• 2016

In this paper, a dual mode buck converter with an ability to change mode is proposed, which is suitable particularly for portable device. The problem of conventional mode control circuit is affected by load variation condition such as suddenly or slowly. To resolve this problem, the mode control was designed with slow clock method. Also, when change from the PFM(Pulse Frequency Modulation) mode to the PWM(Pulse Width Modulation) mode, to use the counter to detect a high load. And the user can select mode transition point in load range from 20mA to 90mA by 3 bit digital signal. The circuits are implemented by using BCDMOS 0.18um 2-polt 3-metal process. Measurement environment are input voltage 3.7V, output voltage 1.2V and load current range from 10uA to 500mA. And measurement result show that the peak efficiency is 86% and ripple voltage is less 32mV.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.4
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• pp.531-537
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• 2018

This paper propose a bidirectional dc-to-dc converter employing dual inductor for current ripple reduction. Conventional bidirectional dc-to-dc converter uses a single inductor for two different modes; boost and buck; therefore it is difficult to satisfy the optimized inductance value for each mode. To improve this problem, the proposed converter adds two switches, a diode, and one inductor. By proper switching of the additional switch, the proposed converter operates with a inductor in boost mode, but it works with dual inductor in buck mode. Hence in both modes the proposed bidirectional converter can be operated with optimized inductance values. Most of all the optimized inductance in buck mode can reduce the current ripple and its effective value(rms), which are directly related to the temperature increase resulted in short lifetime of battery. To verify the validity of the proposed approach, we first analyzes the operation of the proposed converter theoretically, and implement computer-aided simulations and experiments using a prototype.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.1
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• pp.7-12
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• 2008

A GNSS(Global Navigation Satellite System) using GPS provides us with very useful information concerning the positioning of users in many sectors such as transportation, social services, the justice system and customs services, public works, search and rescue systems and leisure. A GNSS using the Galileo satellite is due to work in 2008 and expected to be used in various fields such as aviation, marine transportation, land surveying, resources development precise agriculture, telemetics, and so on. In this paper, we discuss the implementation and testing of a combined GPS/Galileo receiver which we named KSTAR V1.0. Each tracking module of GPS/Galileo dual mode correlator has the five track arms which consist of Very Early code, Early code, Prompt code, late code, and Very late code. Each of 24 tracking modules can be assigned to GPS and/or Galileo signal by changing mode selection register. The basic correlator integration dump period is set to 1ms for GPS C/A code and fast Galileo signal tracking. The performance of the developed combined GPS/Galileo receiver was tested and evaluated using the IF (Intermediated Frequency)-level GPS/Galileo signal generator.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.573-579
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• 2015

A control algorithm of thyristor dual converter power system is proposed in this study for a railway power substation. The thyristor dual converter can use regenerative power without an additional system using control algorithm. An autonomous voltage and mode change method is also proposed to provide uninterrupted power to the railway. A 10 kW reduced model of the thyristor dual converter power system is built and tested to verify the validity of the proposed control algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.465-467
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• 2015

This paper implements a dual-mode power strip controller (PSCtrl) with environmental sensors which cooperates with Android-based smartphones. According to the statistics on fires in housing facilities, unidentified electrical fires account for 23.4%. In order to reduce these fire accidents caused by user carelessness and protect life and property, smart power control techniques with improved user convenience are required. For this reason, the implemented dual-mode PSCtrl controls ON-OFF operations of a power strip in two ways (e.g. manual and automatic modes) by cooperating with Android-based smartphones provided with environmental data from light, temperature, and humidity sensors. In manual mode, users check environmental data displayed on Android-based smartphones, forcibly controlling the ON-OFF operations through the dual-mode PSCtrl, and in automatic mode, when environmental data exceeds the threshold set by users in advance, the dual-mode PSCtrl automatically controls the ON-OFF operations. Some experimental tests verify successful dual-mode operations of the implemented dual-mode PSCtrl.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1217-1223
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• 2014

A novel half load-cycle worked dual input single output (DISO) DC/AC inverter is presented. The basic circuit consists of a dual buck regulator, which works in continuous current mode. The working principle of DISO DC/AC inverter has been used. The control method applied for half load-cycle worked DISO DC/AC inverter has been studied. The control effects of the open-loop proportional control and closed-loop proportional-integral control are compared by using PSIM software. The parameters are adopted in the realistic simulation and experiment test. Moreover, the waveforms, such as voltage of modulation reference signal and output voltage, were given. The simulation and experiment results proved that the half load-cycle worked DISO DC/AC inverter could achieve good performance, gain a line frequency of 50 Hz, and verify the correctness of theoretical analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1437-1443
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• 2017

Electric energy is consumed or regenerated according to an operation of electric rail cars in urban railway power substations. A thyristor dual converter system is used to deal with the electric energy. Since the AC input voltage of power substations is $22.9kV{\pm}10%$, the magnitude of the AC voltage fluctuates according to load conditions, so the secondary side voltage of the DDY transformer also fluctuates. In the thyristor dual converter, the response characteristics of the DC output voltage and the DC output current are changed based on an initial firing angle in the cross mode conversion between the forward mode and the reverse mode. Therefore, this paper proposes the initial firing angle tracking algorithm considering fluctuation of the AC input voltage. The effectiveness of the proposed algorithm is verified by a simulation compared with the conventional algorithm.

• Journal of IKEEE
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• v.14 no.1
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• pp.40-46
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• 2010

This paper describes a clock and data recovery (CDR) circuit that supports dual data rates of 2.7Gbps and 1.62Gbps for DisplayPort standard. The proposed CDR has a dual mode voltage-controlled oscillator (VCO) that changes the operating frequency with a "Mode" switch control. The chip has been implemented using $0.18{\mu}m$ CMOS process. Measured results show the circuit exhibits peak-to-peak jitters of 37ps(@2.7Gbps) and 27ps(@1.62Gbps) in the recovered data. The power dissipation is 80mW at 2.7Gbps rate from a 1.8V supply.