• Journal of the Korea Society for Simulation
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• v.8 no.4
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• pp.33-51
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• 1999

In this study, the system level network simulation is considered with adaptive array antenna in CDMA mobile communication system. A network simulation framework is implemented based on IS-95A/B system to consider dynamic handoff, system level network behavior, and deploying strategy into the overall CDMA mobile communication network under adaptive array algorithm. Its simulation model, such as vector channel model, adaptive beam forming antenna model, handoff model, and power control model, are described in detail with simulation block. In order to maximize SINR of received signal at antenna, Maximin algorithm is particularly considered, and it is computed at each simulation snap shot with SINR based power control and handoff algorithm. Graphic user interface in this system level network simulator is also implemented to define the simulation environments and to represent simulation results on real mapping system. This paper also shows some features of simulation framework and simulation results.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.880-885
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• 2003

Using a Assistance Power Sources of the Railroad Vehicles Three-Level ZVZCS DC/DC Converter is presented in this paper. The proposed three-Level DC/DC Converter Is to achieved zero voltage and zero current switching for the two Main switches. phase shift method is used a parastic capacitance by reverse recovery characteritics in a inner diode of the switching device. Also. using a diode second part of the Transformer by the simple auxiliary circuit for the achieved zero current switching of the Auxiliary switch. For the ZVZCS movement of the all switching devices is analyzed and verified under a 5kW, in the 100kHz switching frequency.

• Journal of Power Electronics
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• v.16 no.2
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• pp.498-511
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• 2016

This paper presents a single-phase five-level inverter controlled by two novel pulse width modulation (PWM) switching techniques. The proposed PWM techniques are designed based on minimum switching power loss and minimum total harmonic distortion (THD). In a single-phase five-level inverter employing six switches, the first proposed PWM technique requires four switches to operate at switching frequency and two other switches to operate at line frequency. The second proposed PWM technique requires only two switches to operate at switching frequency and the rest of the switches to operate at line frequency. Compared with conventional PWM techniques for single-phase five-level inverters, the proposed PWM techniques offer high efficiency and low harmonic components in the output voltage. The validity of the proposed PWM switching techniques in controlling single-phase five-level inverters to regulate load voltage is verified experimentally using a 100 V, 500 W laboratory prototype controlled by dspace 1103.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.111-121
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• 1995

A fuzzy control algorithm of bell-type membership functions and 9 rules is constructed for narrow range level control of steam generators in nuclear power plants. It is implemented at a field digital distributed controller, a Westinghouse-made controller called Westinghouse Distributed Processing Family(WDPF). Performance for level control of the developed fuzzy controller is compared with that of conventional controller, both at the field controller. For these comparisons, both the fuzzy control algorithm and the conventional PI control algorithm were carefully tuned. Also the sampling time for optimal performance was investigated. The results show that the fuzzy control algorithm is not only better in performance than the conventional algorithm but also much easier to be tuned by operators in the field.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.107-113
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• 2001

This paper describes dynamic performance analysis of a STATCOM based on 3-level inverter. Major attention is focused on the controller design for 3-level inverter, including regulator design for voltage sharing across the dc link capacitors. A detailed simulation model was developed with Matlab and a scaled hardware model was built and tested to verify the proposed approach. Both simulation and experimental results confirm that the developed controller can regulate the reactive power. The developed controller could be effectively applied to the actual hardware system for STATCOM.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.341-351
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• 1996

The values for the average and rms currents in a three-level PWM inverter are required in order to select the various components such as power semiconductor devices, capacitors and reactors of inverter circuit. And those are very useful for the designing of the heat sink. In this paper, therefore, the simple current equations are proposed for a three-level PWM inverter. Analysis of inverter current waveforms indicate that the average and rms inverter currents are dependent on the load power factor and PWM modulation index (Ma). Error analysis and experiment results verify the effectiveness of the proposed current equations. (author). refs., figs., tabs.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.339-344
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• 2004

This paper proposes transformerless power conversion system consisting of a single-phase diode rectifier and a shunt hybrid filter for the electric-railway system. The hybrid filter consists of a single tuned LC filter per a phase and a low-rated NPC type multi-level inverter. Compared with conventional active filters. transformers are not used. Also, LC filter works as not only a harmonic filter tuned at the 3rd harmonic frequency but also a switching-ripple filter. The rating of the active filter can be decreased by using a NPC type multi-level inverter. The simulation results confirm the validity of the system.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.326-332
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• 2018

In this paper, the design process and the control method of the power conversion system (PCS) that consists of a bidirectional DC-DC converter and a 3-level T-type inverter for an energy storage system is presented. Especially the design method of the output LCL filter for a 3-lvel T-type inverter without complex mathematical process are proposed. The validity of the control method and design process in this paper are verified through simulation and experimental analysis.

• Journal of Power Electronics
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• v.14 no.3
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• pp.499-506
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• 2014

This paper proposes a 3 kW single-phase bi-directional multi-level converter for energy storage applications. The proposed topology is based on the H-bridge structure with four switches connected to the DC-link. A simple phase opposition disposition PWM method that requires only one carrier signal is also suggested. The switching sequence to balance the capacitor voltage is considered. The topology can be extended to a nine-level converter or a three-phase system. The operating principle of the proposed converter is verified through a simulation and an experiment.

• Journal of Power Electronics
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• v.19 no.4
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• pp.944-955
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• 2019

In this paper, the three-level T-type neutral-point-clamped indirect matrix converter topology and the relative space vector modulation methods are introduced to improve the voltage transfer ratio and output voltage performance. The presented converter topology is based on combinations of cascaded-rectifier and three-level T-type neutral-point-clamp inverter. It can overcome the limitation of voltage transfer ratio of the conventional matrix converter and the high voltage rating of power switches of conventional matrix converter. Two SVPWM strategies for proposed converter are described in this paper to achieve the advantages features such as: sinusoidal input/output currents and three-level output voltage waveforms. Results from Psim 9.0 software simulation are provided to confirm the theoretical analysis. Hence, a laboratory prototype was implemented, and the experimental results are shown to validate the simulation results and to verify the effectiveness of the proposed topology and modulation strategies.