• Journal of Power Electronics
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• v.14 no.3
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• pp.507-518
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• 2014

This paper presents a new cascaded asymmetrical single phase multilevel converter with a lower number of power semiconductor switches and isolated DC sources. Therefore, the number of power electronic devices, converter losses, size, and cost are reduced. The proposed multilevel converter topology consists of two H-bridges connected in cascaded configuration. One H-bridge operates at a high frequency (high frequency inverter) and is capable of developing a two level output while the other H-bridge operates at the fundamental frequency (low frequency inverter) and is capable of developing a multilevel output. The addition of each power electronic switch to the low frequency inverter increases the number of levels by four. This paper also introduces a hybrid switching algorithm which uses very simple arithmetic and logical operations. The simplified hybrid switching algorithm is generalized for any number of levels. The proposed simplified switching algorithm is developed using a TMS320F2812 DSP board. The operation and performance of the proposed multilevel converter are verified by simulations using MATLAB/SIMULINK and experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1186-1192
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• 2015

This paper proposes an economical method that the phase currents can be measured and reconstructed by means of the leg-shunt resistors in the 3-leg 2-phase vector-controlled inverter for 2-phase induction motor. In general, the phase currents of 2-phase induction motor have been measured using two Hall current sensors. However, because Hall current sensors are expensive, economically disadvantageous to apply in low power applications. The proposed method is verified by computer simulations and experiments to show the good performance of the vector control.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.23-30
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• 2009

A new high performance and low cost unified power system is proposed through investigating conventional Power-Integrated Drive(PID) system and Power-Separated Drive(PSD) system applied to LCD TV. Since the proposed system consists of two stage, namely power and inverter stage it features high efficiency and cost effectiveness. To satisfy the safety standard of the High voltage transformer, 1:1 transformer is employed between inverter and high voltage transformer. Moreover, to ensure the Zero Voltage Switching(ZVS) of all power switches and the Pulse Count Modulation(PCM) method is employed, which controls the number of pulse at the fixed frequency and fixed duty cycle. Therefore, it features high efficiency, improved heat generation, cost effectiveness and good EMI performance including no additional current balancing coil. To confirm the validity of proposed system, comparison of conventional system, verification of experimental results are presented.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.708-711
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• 2000

Sensorless PMSM is much studied for the industrial applications and home appliances because a mechanical sensor reduce reliability and increase cost. Most of sensorless algorithms are based on motor equations, and so the magnitude of phase voltage and current should be exactly obtained. However, the inverter output voltage applied to PMSM has relatively large error in the low speed range, and a relatively poor response is shown in the low speed range. This paper investigates the improved performance of sensorless PMSM in the low speed range. This paper proposes the error reduction of inverter output voltage which is realized through the variable link voltage. The proposed algorithm is verified through simulation and experiment.

• Journal of Power Electronics
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• v.11 no.4
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• pp.606-611
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• 2011

Power electronics is a key technology for electric, hybrid, plug-in hybrid, and fuel cell vehicles. Typical power electronics converters used in electric drive vehicles include dc/dc converters, inverters, and battery chargers. New semiconductor materials such as silicon carbide (SiC) and novel topologies such as the Z-source inverter (ZSI) have a great deal of potential to improve the overall performance of these vehicles. In this paper, a Z-source inverter for fuel cell vehicle application is examined under three different scenarios. 1. a ZSI with Si IGBT modules, 2. a ZSI with hybrid modules, Si IGBTs/SiC Schottky diodes, and 3. a ZSI with SiC MOSFETs/SiC Schottky diodes. Then, a comparison of the three scenarios is conducted. Conduction loss, switching loss, reverse recovery loss, and efficiency are considered for comparison. A conclusion is drawn that the SiC devices can improve the inverter and inverter-motor efficiency, and reduce the system size and cost due to the low loss properties of SiC devices. A comparison between a ZSI and traditional PWM inverters with SiC devices is also presented in this paper. Based on this comparison, the Z-source inverter produces the highest efficiency.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.317-320
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• 2000

This paper proposes a voltage compensation method to improve the control performance of B4 inverter which is studied for low-cost drive systems. The B4 inverter employs only four switches and it has a center-tapped connection in the split dc-link capacitors to one phase of a three-phase motor. In the B4 topology unbalan-cd three-phase voltages will be generated by the dc link voltage ripple. To solve this problem we present a voltage compensation method which adjusts switching times considering dc link voltage ripple. The proposed method is verified by simulation results,

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.322-331
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• 2002

In this paper, a single-phase to three-phase PWM converter topology using a single-phase half-bridge PWM rectifier and a 2-leg inverter for low cost three-phase induction motor drives is proposed. In addition, the source voltage sensor is eliminated with a state observer which controls the deviation between the model current and the system current to be zero. The converter topology is of lower cost than the conventional one, which gives sinusoidal input current, unity power factor, dc output voltage control, bidirectional power flow and VVVF output voltage. The experimental results for V/F control of 3Hp induction motor drives have been shown.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.14-20
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• 1997

Due to several advantages of Pulse Width Modulated(PWM) Converter, such as unity power factor with low-harmonics and energy regeneration, PWM converter has been widely used in industrial application. In every application of energy conversion equipment, the design and implementation must be carried out considering performance and cost. High quality with low cost is the best choice for energy conversion equipment. High dc link voltage can reduce inverter and motor side losses and system dimension compare to low dc link voltage. Analog controller can make PWM converter cheaper without considerable degradation of the performance than digital controller. This paper shows the simplified analog controller-for 600V dc link voltage using stationary reference frame control and the simulation results.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.89-92
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• 2001

Silent gas discharge method has been widely applied for ozone production, ultraviolet light and UV laser generation. Since ozone and ultraviolet applications have tendency to spread widely in industry, the development of efficient and low-cost power supply for such systems is a task of great impotency. This paper introduces high-frequency inverter type mode power supply designed for ozone generation tube and ultraviolet generation excimer lamp and considerations on this inverter and pulse density modulation control strategy applied in it.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1067-1074
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• 2018

This paper presents a control method for variable-speed motor drives that do not use a DC-link electrolytic capacitor. The proposed circuit consists of a power factor correction converter for boosting the DC-link voltage, an inverter for driving the motor, and a small DC-link film capacitor. By employing a small DC-link capacitor, the proposed circuit that is small, and a low cost and weight are achieved. However, because the DC-link voltage varies periodically, the control of the circuit is more difficult than that of the conventional method. Using the proposed control method, an inverter can be controlled reliably even when the capacitance of the DC-link capacitor is very small. Experiments are performed using a 1.5-kW inverter with a $20-{\mu}F$ DC-link capacitor, and the experimental results are analyzed thoroughly.