• Journal of Power Electronics
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• v.18 no.4
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• pp.1015-1026
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• 2018

A family of dual-DC-input (DI) dual-buck inverters (DBIs) is proposed by employing a DI switching cell as the input of traditional DBIs. Three power ports, i.e. a low voltage DC input port, a high voltage DC input port and an AC output port, are provided by the proposed DI-DBIs. A low voltage DC source, whose voltage is lower than the peak amplitude of the AC side voltage, can be directly connected to the DI-DBI. This supplies power to the AC side in single-stage power conversion. When compared with traditional DBI-based two-stage DC/AC power systems, the conversion stages are reduced, and the power rating and power losses of the front-end Boost converter of the DI-DBI are reduced. In addition, five voltage-levels are generated with the help of the two DC input ports, which is a benefit in terms of reducing the voltage stresses and switching losses of switches. The topology derivation method, operation principles, modulation strategy and characteristics of the proposed inverter are analyzed in-depth. Experimental results are provided to verify the effectiveness and feasibility of the proposed DI-DBIs.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.5
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• pp.501-507
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• 2000

A nobel low-cost, simple and unity-power-factor electronic ballast is presented. The proposed electronic ballast employs a bypassing capacitor- and load networks composed of ballast capacitors and small charge pump capacitors as power factor correction circuit combined with the secondary winding of the transformer in the self-excited current-fed push-pull resonant inverter(CF-PPRI), resulting in cost-effectiveness and higher efficiency. By analyzing the princip1es of power factor correction mathematically, optimum design guidelines are presented. Since the lamps are used in power factor correction stage, the input power is automatically adjusted according to the number of the lamps.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1064-1070
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• 2007

This paper presents a grid-interactive current controlled voltage source inverter (CCVSI) with uniterruptible power supply (UPS), which uses an inner current control loop (polarized ramp time (PRT)) and outer feedback control loops to improve grid power quality and UPS. To reduce the complexity, cost and number of power conversions, which results in higher efficiency, a single stage CCVSI is used. The operation of this system could be divided into the power quality control (PQC) state mode and the UPS state mode. In PQC mode, the system operated to compensate the reactive power demand by nonlinear load or variation in load. In UPS mode. the system is controlled to provide a sinusoidal voltage at the rated value for the load when the gird fail. To verify the proposed system, a comprehensive evaluation with theoretical analysis, simulation and experimental results for 1KVA load capacity is presented.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.79-85
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• 2016

In this study, we proposed a new single-stage small power MH lamp electronic ballast and power-factor correction circuit with improved circuit by the current of passive power factor correction. Main circuit integrates traditional DC/DC and DC/AC circuits into one-stage DC/AC inverter. Moreover, we described the working principle and control strategy of the new circuit; it's soft switching principle; and resonant element parameter design formula. An experimental prototype of HID lamp electronic ballast with output power of 70 W was built to verify the feasibility of the analysis and design. The simulation and experimental results proved that the power factor of this circuit could reach 94%, with efficiency of 90%. The input current harmonics conform to IEC 61000-3-2 standards and its cost is low. These superior performances of the new circuit indicate certain practical values.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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• pp.486-494
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• 2012

In this paper, we proposes the three-phase embedded Z-source inverter consisting of the three embedded Z-source converters and it's the output voltage control method. Each embedded Z-source converter can produce the bipolar output capacitor voltages according to duty ratio D such as single-phase PWM inverter. The output AC voltage of the proposed system is obtained as the difference in the output capacitor voltages of each converter, and the L-C output filter is not required. Because the output AC voltage can be stepped up and down, the boost DC converter in the conventional two-stage inverter is unnecessary. To confirm the validity of the proposed system, PSIM simulation and a DSP based experiment were performed under the condition of the input DC voltage 38V, load $100{\Omega}$, and switching frequency 30kHz. Each converter is connected by Y-connection for three-phase loads. In case that the output phase voltage is the same $38V_{peak}$ as the input DC voltage and is the 1.5 times($57V_{peak}$), the simulation and experimental results ; capacitor voltages, output phase voltages, output line voltages, inductor currents, and switch voltages were verified and discussed.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.2
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• pp.22-28
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• 1998

A $g_m$-control technique using a new electronic zener diode (EZD) for CMOS rail-torail input stages is presented. A regulated CMOS inverter is used as an EZD to obtain a constant-$g_m$ input stage. The turn-off characteristic of the proposed EZD is better than that of the existing EZD using two complementarey diodes, and thus, better $g_m$-control can be achieved. With this input stage, a 3V constant-$g_m$ rail-to-rail CMOS op-amp has been designed and fabricated using a $0.8\mu\extrm{m}$single-poly, double-metal CMOS process. Measurements results show that the $g_m$ variation is about 6% over the entire input common-mode range, and the op-amp has a dc gain of 88dB and a unity-gain frequency of 4MHz for $C_L=20pF, R_L=10k\Omega$

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.345-348
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• 2001

In this paper, the development of input power factor and harmonic distortion of line current were showed in the proposed single-stage SRM inverter. It is verified from the experiments that the proposed encoder and logic controller can be a powerful candidate for the practical low cost SRM drive.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.6
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• pp.514-524
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• 2016

This work suggests a study on 5 kW plasma power supply design and reactor capacitance estimation algorithm for a wide range of linear output control to operate a plasma reactor. The suggested study is designed to use a two-stage circuit and control the full-bridge circuit of the two-stage circuit using the buck converter output voltage of the single-stage circuit. The switching frequency of the full-bridge circuit is designed to operate through high-frequency switching and obtain maximum output using LC parallel resonance. Soft switching technique(ZVS) is used to reduce the loss caused by high-frequency switching, and duty control of the buck converter is applied to control a wide range of linear output. The internal capacitance of the reactor cannot easily be extracted, and thus, the reactor cannot be operated in an optimized resonant state. To address this issue, this work designs the internal capacitance of the reactor such that estimations can be performed with the developed reactor capacitance estimation algorithm applied to the internal capacitance of the reactor. A 5 kW plasma power supply is designed for a wide range of linear output control, and the validity of the study on the reactor capacitance estimation algorithm is verified.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.73-76
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• 2003

A zero voltage soft switching inverter using active clamp is presented for induction heating application. This converter have long been attractive because of its simplicity, high efficiency, and low cost compared to other schemes. In addition to those merits, Input power factor can be improved with a variable frequency control. In this paper, it describe the control method and operational principle to improve a power factor with a single stage US converter using active clamp for induction heating application.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.626-629
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• 1997

The urban transit propelled by single sided linear induction motor(SLIM) have been in stage for practical application. Also, the use of the linear induction motor in traction systems enables large forces to be achieved without friction between wheels and rails. In this paper we discuss the linear induction motor (LIM) drive system (300KVA) for magnetic levitation vehicles.