• Journal of Power Electronics
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• v.11 no.6
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• pp.779-786
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• 2011

This paper presents a soft switching converter to achieve the functions of zero voltage switching (ZVS) turn-on for the power switches and dc voltage step-up. Two circuit modules are connected in parallel in order to achieve load current sharing and to reduce the size of the transformer core. An active snubber is connected between two transformers in order to absorb the energy stored in the leakage and magnetizing inductances and to limit the voltage stresses across the switches. During the commutation stage of the two complementary switches, the output capacitance of the two switches and the leakage inductance of the transformers are resonant. Thus, the power switches can be turned on under ZVS. No output filter inductor is used in the proposed converter and the voltage stresses of the output diodes is clamped to the output voltage. The circuit configuration, the operation principles and the design considerations are presented. Finally, laboratory experiments with a 340W prototype, verifying the effectiveness of the proposed converter, are described.

• Journal of Power Electronics
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• v.13 no.1
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• pp.51-58
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• 2013

This paper proposes the power conversion mechanism of a bailer-charge-transfer zero-current-switching (CT-ZCS) circuit. The operation modes are analyzed and researched using state trajectory equations. The topology of CT-ZCS based on soft-switching inverters offers some merits such as: tracking the input reference signal dynamically, bearing load shock and short circuit, multiplying inverter N+1 redundancy parallel, coordinating power balance for easy control, and soft-switching commutation for high efficiency and large capacity. These advantages are distinctive from conventional inverter topologies and are especially demanded in AC drives: new energy generation and grid, distributed generation systems, switching power amplifier, active power filter, and reactive power compensation and so on. Prototype is manufactured and experiment results show the feasibility and dynamic voltage-tracking characteristics of the topology.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.337-338
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• 2013

Combination the several type of single phase power conversion utilized simply topology are proposed in this paper. Totally four kind of converter are investigated, they are Boost AC/AC Converter, Buck AC/AC Converter, Boost AC/DC Converter, and Buck DC/AC Converter. Two types action mode are presented to determine the functional of circuit. First is AC chopper action mode, representation of the AC/AC converter. AC chopper action mode offered the sinusoidal current waveform, better power factor, faster dynamics, and smaller input/output filter. They present high robustness, offer safe commutation and have high efficiency. The second is full bridge action mode, determined the transformation AC to DC power and otherwise. Four switching devices and one magnetic contactor will establish the mode operation of circuit and manage the flow of power proceed in proper. The correction and advance of the kind of converter are verified by simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.527-533
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• 1998

An optimized PWM switching strategy for an induction motor voltage control is developed and demonstrated. Space vector modulation in voltage source inverter offers improved DC-bus utilization and reduced commutation losses, and has been therefor recognizedas the perfered PWM method, especially in the case of digital implementation. Three-phase invertor voltage control by space vector modulation consists of switching between the two active and one zero voltage vector by using the proposed optimal PWM algorithm. The prefered switching sequence is defined as a function of the modulation index and period of a carrier wave. The sequence is selected by suing the inverter switching losses and the current ripple as the criteria. For low and medium power application, the experimental results indicate that good dynamic response and reduced harmonic distortion can be achieved by increasing switching frequency.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.638-640
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• 2000

The main source of vibration in SRM drive is generated by rapid change of radial force when phase current is extinguished by commutation action. In this paper a hybrid excitation method is proposed to reduce vibration and acoustic noise of SRM. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are reduced because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3078-3080
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• 2000

In this paper. we designed a high precision Linear DC Motor(LDM) Driver with $120^{\circ}$ commutation method. It was composed of three parts which were divided into Power and Inverter Circuit. Analog Circuit with PWM Generation and Fault Protections. and Logic Circuit. We selected PMAC Controller by Delta Tau Co. for testifying a high accuracy of a designed driver. A high precision driver enhanced a response to changes of velocity and acceleration in motion and improved the accuracy.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.15-18
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• 2005

Switched reluctance drive does exhibit higher levels of vibration and acoustic noise than that of most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial magnetic force when phase current is extinguished during commutation action. In this paper, some excitation method is proposed to reduce vibration and acoustic noise of the switched reluctance drive. The excitation strategies considered in this research are 1-phase, 2-phase and hybrid excitation method. 1-phase method is a conventional and 2-phase method is excited 2 phases simultaneously. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are compared and tested. Suggested 2-phase and hybrid strategies reduce acoustic noise because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.121-127
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• 2012

An electric power compensation system for a DC transmission system with an integrated wind turbine generator is proposed. The proposed compensation system consists of a synchronous generator and a duplex reactor. This apparatus is connected to the sending-end circuit of the DC transmission system. A set of steady-state equations of the system is first derived. Then, the effect of the duplex reactor, which can eliminate the sending-end grid current distortion due to commutation of the converter, is explored. The relationships among power at the sending-end circuit are also revealed. It is shown that fluctuations in the sending-end grid power due to changes in wind velocities are compensated with the proposed system. Finally, the effects of the sending-end grid conditions on the steady-state characteristics of the system are studied.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.12
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• pp.715-726
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• 1999

This paper estimates the capacity of shunt type active power filters(APF) for harmonic/reactive power compensation with a thyristor converter load. The base capacity requirement of APF is defined for idealized converter load current waveform and the effect of commutation overlap on the APF capacity is examined. The APF capacity required for reactive power compensation in addition to the harmonic elimination is estimated to give maximum achievable power factor for various operating condition of the partially-loaded thyristor converter. The method of current limit of APF is introduced, and it is shown that the APF capacity can be considerably reduced by deliberately limiting the peak current while maintaining the filtering performance to meet the level std 519 regulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.8
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• pp.500-508
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• 2004

This paper presents a new sensorless vector control system for high performance induction motor drives fed by a matrix converter with non-linearity compensation and disturbance observer. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching device is corrected by a new matrix converter modeling. The lumped disturbances such as parameter variation and load disturbance of the system are estimated by the radial basis function network (RBFN). An adaptive observer is also employed to bring better responses at the low speed operation. Experimental results are shown to illustrate the performance of the proposed system.