• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.2
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• pp.88-95
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• 2008

This paper proposes a fast fault detection algorithm under open-circuit fault of a switch for a brushless DC(BLDC) motor drive system. This proposed method is configured without the additional devices for fault detection and identification. The fault detection and identification are achieved by a simple algorithm using the operating characteristic of the BLDC motor. After the fault identification, the drive system is reconfigured for continuous operation. This system is reconfigured by four-switch topology connecting a faulty leg to the middle point of DC-link bidirectional switches. This proposed method can also be embedded into existing BLDC motor drive systems as a subroutine without excessive computational effort. The feasibility of a the proposed fault detection algorithm is validated in simulation and experiment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.129-134
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• 2021

Recently, the demand for electricity is gradually increasing due to the rapid industrial development and the improvement of living standards. In the case of Korea, which is highly dependent on fossil fuels due to such a surge in electricity demand, reduction and freezing of greenhouse gas emissions due to international environmental regulations will immediately lead to a contraction in industrial activities. Accordingly, there are many difficulties in competition with advanced countries that want to link the environment with the country's industrial production activities, and the development of alternative energy as a countermeasure is of great interest around the world. Among these new power generation methods, small-scale power generation facilities with relatively small capacity include photovoltaic generation, wind power generation, and fuel cell generation. Among them, the fuel cell attracts the most attention in consideration of continuous operation, high power generation efficiency, and long-term durability, which are important factors for practical use. Therefore, in this paper, the fuel cell power generation system was researched and constructed by designing the power conversion circuit necessary to finally obtain the AC power used in our daily life by using the DC power generated from the fuel cell as an input.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.538-545
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• 2001

In this paper a gearless drive system using a permanent-maget synchronous motor for high speed elevators is addressed. The application of permanent magnet synchronous motor to an elevator traction machine enables several improvements including higher efficiency better ride comfort smaller size and lighter weight and so on A PWM boost converter has been also adopted so that DC-link voltage regulation bi-directional power flow and controllable power factor with reduced input current harmonics are possible. To increase the reliability and performance of overall control system the unified control board which can include the car and group controller as well as PWN converter/inverter controller has been designed based on a DSP TMS320VV33. In addition the dynamic load simulator system has been developed so that the drive system of high speed elevator can be tested and evaluated without and limitation on ride distance. Some experimental results are given to verify the effectiveness of the developed system.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.121-126
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• 2013

Cycloconverter used as a power conversion device in the speed and torque control system of AC machines has the advantage of a simple control and a large torque at low speed. In addition, because a rectifier, a DC link, and an inverter are not installed, this system is simple and suitable for large power system. If a power conversion device, which is currently used as a propulsion motor of large vessel, is changed into cycloconverter, the system is simplified and then the installation costs can be significantly reduced. However, conventional cycloconverter has the increased harmonics because the power loss is large and the waveform of output voltage is distorted, due to the high-speed switching of power semiconductor devices. In order to improve these shortcomings, this paper describes a phase shifting filter which is composed of two inputs with different phases in the primary side and one output in the secondary one. As the voltage waveforms with two different phases are added and transformed into the secondary side, these outputs are close to sinusoidal waves. Thereby the voltage waveforms, which are applied to the propulsion motors, are improved and total harmonic distortions (THDs) are significantly reduced.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.125-131
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• 2001

This paper presents a application of vector control strategy to 1.2MVA traction drive for railway vehicle. The vector control required the control of the phase and amplitude of output voltage vector. But in case of traction system for railway vehicle, the one-pulse mode is used at high speed region in order to utilize the link voltage fully. So it is impossible to control the flux and torque axis current instantaneously and independently in the region. So this paper proposes a mixed control algorithm, where the vector control strategy at low speed region and slip-frequency control strategy at high speed region is used. And precise switching technique between the two different control strategy is proposed. The proposed strategy is verified by experimental results with a 1.2MVA traction drive system with four 210kW induction motors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.12
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• pp.1093-1098
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• 2007

Tilting trains are currently in operation in 13 countries around the world. With the advances in tilting technology, verification of economic efficiency, and changes in economic situations, the introduction of tilting trains will rapidly spread across the globe. The measurement system is composed of the industrial computers installed in the console and the measurement racks mounted on each car. It is utilized to accumulate the data by the communication card and the optical cable. The optical cable and power cable are coupled at the connector located in joint of train to make easy to disconnect car each other. The signal conditioner is designed to choose and to extend the channel for each sensor readily. The sensor measurement rack has adopted as decentralization method. It is installed in each car to minimize the cable length. In also, it is manufactured based on 19"rack and covered to protect the cable. In this study, the programs for measurement and analysis were also developed to understand the traction system characteristics of TTX. Using this measurement system, we studied that acceleration test, re-powering test, and gradually powering test. The acceleration performance of TTX is 1.735 km/h/s, and it is inner standard value. The notch test result from 1 to 7 steps, DC link voltage is under standard value, and the output electric current of inverter is controlled normally. From the test results, we saw the performances of the traction systems are normal.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.411-419
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• 2005

In this paper, a sliding mode observer for solar array current estimation in the photovoltaic power generation system is presented. The solar array current estimation Information is obtained from the sliding mode observer and fed into the maximum power point tracker to update the reference voltage. The parameter values such as inverter dc link capacitances cm be changed up to 50$\%$ from their nominal values and the linear observer can't estimate the correct state values under the parameter variations and noisy environments. The configuration of sliding mode observer is simple, but it shows the robust tracking performance against parameter variations and modeling uncertainties. In this paper, the method for constructing the sliding mode observer using equivalent control input is presented and the convergence of the proposed observer is verified by the Lyapunov method. The mathematical modeling and the experimental results verify the validity of the proposed method.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.1
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• pp.11-19
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• 2011

This paper describe development of a hardware simulator for the DFIG wind power system, which was designed considering wind characteristic, blade characteristic, and blade inertia compensation. The simulator consists of three major parts, such as wind turbine model using induction motor, doubly-fed induction generator, converter-inverter set. and control system. The turbine simulator generates torque and speed signals for a specific wind turbine with respect to the given wind speed which is detected by Anemometer. This torque and speed signals are scaled down to fit the input of 3.5kW DFIG. The MSC operates to track the maximum power point, and the GSC controls the active and reactive power supplied to the grid. The operational feasibility was verified through computer simulations with PSCAD/EMTDC. And the implementation feasibility was confirmed through experimental works with a hardware set-up.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.5
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• pp.62-70
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• 2007

In this paper, the boost Power Factor Correction(PFC) technique for Direct Torque Control(DTC) of brushless DC motor drive in the constant torque region is implemented on a TMS320F2812DSP. Unlike conventional six-step PWM current control, by properly selecting the inverter voltage space vectors of the two-phase conduction mode from a simple look-up table at a predefined sampling time, the desired quasi-square wave current is obtained, therefore a much faster torque response is achieved compared to conventional current control. Furthermore, to eliminate the low-frequency torque oscillations caused by the non-ideal trapezoidal shape of the actual back-EMF waveform of the BLDC motor, a pre-stored back-EMF versus position look-up table is designed. The duty cycle of the boost converter is determined by a control algorithm based on the input voltage, output voltage which is the dc-link of the BLDC motor drive, and inductor current using average current control method with input voltage feed-forward compensation during each sampling period of the drive system. With the emergence of high-speed digital signal processors(DSPs), both PFC and simple DTC algorithms can be executed during a single sampling period of the BLDC motor drive. In the proposed method, since no PWM algorithm is required for DTC or BLDC motor drive, only one PWM output for the boost converter with 80 kHz switching frequency is used in a TMS320F2812 DSP. The validity and effectiveness of the proposed DTC of BLDC motor drive scheme with PFC are verified through the experimental results. The test results verify that the proposed PFC for DTC of BLDC motor drive improves power factor considerably from 0.77 to as close as 0.9997 with and without load conditions.