• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.696-699
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• 2004

This paper proposes the Low Cost Class-E Converter with Power Conversion Operation of Piezoelectric Transformer. The Power Piezoelectric transformer capacity used in the proposed circuit is 15W and the electric equivalent circuit is presented. Class E type converter has some merits such as small component count, small size, and low cost. The topology has also ZVS conditions for main switch, thus in efficiency aspect, it is also competitive for commercial feasibility. The analysis and design guideline are suggested and also they are verified by experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.10
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• pp.501-507
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• 2001

In this paper, new high-efficiency zero voltage switching (ZVS) AC-DC boost converter is proposed to achieve power factor correction by simplifing energy recovery circuit. A lot of high power factor correction circuits have been proposed and applied to increase input power factor and efficiency. Most of these circuits may obtain unity power factor and achieve sinusoidal current waveform with zero voltage or/and zero current switching. However, it is difficult for them to obtain low cost, small size, low weight, and low noise. The topology proposed to improve these problems can compact the devices in circuit and can achieve high efficiency ZVS AC-DC boost converter. Simulation and experimental results show that this topology is capable of obtaining high power factor and increasing the efficiency of the system.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1383-1386
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• 2005

Non-isolated OSAKA Converter, which removes a three-phase transformer, is described in this paper. The converter switches once in every half cycle of an AC commercial power source. Therefore, it can solve many problems caused by the high frequency operation. The proposed converter achieves the soft-switching operation and the EMI noise can be reduced. In this circuit, the resonant capacitor, which is used for the soft-switching operation, is utilized for the improvement of an input current waveform. To achieve low cost and compact structure, non-isolated OSAKA converter removes a three-phase transformer of the OSAKA converter. By removing the three-phase transformer, three phase currents occur the interferences each other. To avoid the interference, a new switching method for non-isolated OSAKA converter is preposed. The converter can be constructed by the low-speed large power devices. The converter generates the low distorted input current waveforms with high power factor.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.12
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• pp.106-112
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• 1996

A ZVT (zero voltage transition) converter for SRM (switched reluctance motor) drives is proposed in this study. By adding a ZVT-chopping switch in the front-end, all switches in the machine side converter can be operated without any chopping to regulate phase current. This allows the use of low-cost and slow-switching devices for the machine side converter. The ZVT circuitry allows high frequency operation of th echopping switch, which enhnaces the system dynamcis and phase-current ripples. High efficiency of th eintegrated converter is obtained due to low switching losses.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.520-522
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• 2008

A novel two-switch active clamp forward converter suitable for high input voltage applications is proposed. The main advantage of the proposed converter, compared to the conventional active forward converters, is that circuit complexity is reduced and the voltage stress of the main switches is effectively clamped to either the input voltage or the clamping capacitor voltage by two clamping diodes without limiting the maximum duty ratio. Also, the clamping circuit does not include additional active switches, so a low cost can be achieved without degrading the efficiency. Therefore, the proposed converter can feature high efficiency and low cost for high input voltage applications. The operational principles, features, and design considerations of the proposed converter are presented in this paper. The validity of this study is confirmed by the experimental results from a prototype with 200W, 375V input, and 12V output.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.372-376
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• 2001

Due to several advantages of Pulse Width Modulation(PWM) Converter, such as unity power factor operation, elimination of low-order harmonics and regeneration of motor braking energy to source, the application range of PWM Converter has been rapidly extended in industrial application. Nowadays, vector control algorithm and space vector PWM(SVPWM) method are applied to improve the performances of PWM Converter, but vector control algorithm and SVPWM require to use Microprocessor and other digital devices in hardware, causing costly and somewhat large dimension system. In every practical application of energy conversion equipments, the design and implementation should be carried out considering cost and performance. High performance and low cost is the best choice for energy conversion equipments. So, this paper presents the practical design method and implementation results of 3-phase PWM Converter with analog hysteresis current controller, and verifies the performances of unit power factor operation and energy regeneration operation via experimental results.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1146-1147
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• 2008

PV Power Conditioning System (PCS) must have high conversion and low cost. Generally, PV PCS uses either a single converter or multilevel module integrated converter (MIC). Each of these approaches has both advantage and disadvantage. For a high conversion efficiency and low cost of PV module, this paper proposes series connection of module integrated DC-DC converter's output with PV panel. Output voltage of PV panel is connected to the output capacitor of flyback converter. Thus, converter's output voltage is added to the output voltage of PV panel. Isolated DC-DC converter generates only the difference voltage between the PV panel voltage and the required total output voltage. This method reduces power level of DC-DC converter and enhances the energy conversion efficiency compared with conventional DC-DC converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.5
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• pp.391-398
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• 2014

This paper presents a resonant step-down DC/DC converter to reduce the voltage stresses of a 3-phase inverter module under the three-phase AC utility line condition. Under this condition, a conventional 3-phase inverter module suffers from high voltage stresses as a result of the high rectified DC link voltage; hence, a high-cost high-voltage-rating inverter module must be used. However, using the proposed converter, a low-cost low-voltage-rating inverter module may be adopted to drive the motor even under the 3-phase AC line condition. The proposed converter, which can be realized with small size inductor and low-voltage-rating semiconductor devices, operates at a high-efficiency mode because of the zero-current switching operations of all the semiconductor devices. The operational principles are explained and a design example is provided in the study. Experimental results demonstrate the validity of the proposed converter.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.258-261
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• 2001

High Power factor Active Filter converter is used for Inverter Air conditioner power supply to meet IEC standard. In the active filter topology for power factor, extra switch just control the input current indirectly to meet the IEC standard for reducing the cost and size. In this paper, low cost converter was suggested by simulation using extra switch which auxiliary pulse is inserted and quasi resonant soft switching topology control is adapted for panel's inverter air conditioner converter Inserting auxiliary Pulse method to the extra switch has the benefit of reducing THD by low cost input control circuit. And also quasi resonant soft switching topology can reduce switching loss. So both technical is suitable for Panel's Air conditioner.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.201-204
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• 2001

In this paper, a single-phase to three-phase PWM converter topology using six switches only for low cost induction motor drive is proposed. The converter topology is of lower cost than the conventional one, which gives sinusoidal input current, unity power factor, dc output voltage control and bidirectional power flow In addition, the source voltage sensor is eliminated by controlling the deviation between the model current and the system current to be zero. The performance of the proposed converter has been demonstrated through the computer simulation.