• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.4
• /
• pp.339-346
• /
• 2005

It is complex to realize the reference voltage vector by the space vector PWM method in three-leg two-phase inverter In this paper a new PWM technique for three-leg two-phase inverter fed two-phase induction motor is poroposed assuming that three-leg two-phase inverter is equivalent circuit for 'four-leg two-phase inverter with the connected two windings'. From assumption, six sectors are decreased to four sectors, and simple sinusoidal PWM method instead of SVPWM is applied to three-leg two-phase inverter. Also, the switching pattern to determine the switching periods at each sector is proposed. Practical verification of theoretical predictions is presented to confirm the capabilities of the new techniques.

• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.308-312
• /
• 2003

The objective of this paper is to investigate the power spectrum of a three-phase and a two-phase RCD (Random Pulse Centered Displacement) PWM scheme. The two-phase or three-phase pulses of RCD-PWM scheme are mutually center-aligned as in SVM(Space Vector Modulation), but the common pulse center is displaced randomly from the middle of the period. To verify the validity of the proposed two-phase RCD-PWM scheme, the power spectra of the output voltage, the d.c link current in the inverter drives and the radiated acoustic noise are experimentally investigated. And, the performance of the proposed two-phase RCD-PWM scheme was compared and discussed with the conventional three-phase RCD-PWM scheme.

• Proceedings of the KSR Conference
• /
• 1999.05a
• /
• pp.328-335
• /
• 1999

Three phase full bridge rectifier has been used to obtain dc voltage from three phase ac voltage source. The rectifier system has drawbacks that power factor is low and power flow is unidirectional. Therefore, when dc voltage increases due to regeneration of power the dynamic resister for dissipation of regeneration power must be installed. But three phase PWM converter can be controlled to operate with unity power factor and bidirectional power flow. Therefore when the PWM converter is used as do supply system, the dissipating resistor is not necessary. On this thesis, in order to design a controller having good performance, the hee phase PWM converter is completely modeled by using circuit DQ-transformation and thus a general and simple instructive equivalent circuit is obtained; the inductor set becomes a second order gyrator-coupled system and three phase inverter becomes a transformer as well. Under given phase angle(${\alpha}$) and modulation index(MI) of the three phase inverter, the dc and ac characteristics are obtained by analysis of the transformed equivalent circuit The validity of the equivalent circuit is confirmed through PSPICE simulation. And based on the dc and ac characteristics a controller with unity power factor is proposed.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.1 no.4
• /
• pp.472-476
• /
• 2012

In this paper, a sensorless control scheme for a three-phase bi-directional voltage-type PWM rectifier in wind power generation system that operates without the input AC voltage sensors (generator side) is described. The basic principles and classification of the PWM rectifier are analyzed, and then the three-phase mathematical model of the input AC voltage sensorless PWM rectifier control system is established. The proposed scheme has been developed in order to lower the cost of the three-phase PWM rectifier but still achieve excellent output voltage regulation, limited current harmonic content, and unity input power factor.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.414-416
• /
• 2005

In this paper, a new scheme of current programmed control for three phase PWM AC-AC converter is presented. By considering only the magnitude components, a similar scheme in the DC-DC converter can be extended to the three phase PWM AC-AC converter. The proposed current programmed control will be well adopted into various converter topologies though three phase PWM AC-AC boost converter is treated as an example. The converter analysis is carried out by applying the vector DQ transformation to obtain physical insight into the converter operation. Finally, the experiment result shows the validity of the proposed scheme.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.26-33
• /
• 2016

Recently, the use of transformer-less UPS has increased to improve the efficiency of UPS. However, transformer-less UPS is required in three-phase four-wire input IGBT PWM rectifier and the existing three-phase three-wire PFC algorithm cannot be applied in the three-phase four-wire system due to the neutral current problem of UPS input. To control the three-phase four-wire input IGBT PWM rectifier, there are two existing algorithms: 3D SVM and single phase control method. These two algorithms have advantages/disadvantages in controlling the rectifier. The single phase control method is unstable for controlling the rectifier and the 3D SVM method has a problem that must increase the L value of the input-side inductor considerably. Therefore, this paper proposes digital single phase control technology and another new algorithm considering the d-q control, to improve the characteristics of the existing control algorithm. In addition, this paper performed a simulation and experiment based on the proposed control algorithm. The simulation results showed that the proposed technology can control three-phase four-wire IGBT PWM rectifier in a stable manner and can also reduce the neutral current. The proposed algorithm is a useful tool for controlling the three-phase four-wire IGBT PWM rectifier.

• Journal of Power Electronics
• /
• v.8 no.4
• /
• pp.363-370
• /
• 2008

In this paper, three kinds of PWM strategies for a three-phase current-fed dc/dc converter are proposed and compared in terms of losses and voltage transfer ratio. Each PWM strategy is described graphically and their switching losses are analyzed. With the proposed PWM C strategy, one turn-off switching of each bridge switch is eliminated to reduce switching losses under the same switching frequency. In addition, RMS current through the bridge switches is lowered by using parallel connection between two bridge switches and thus, conduction losses of the switches are reduced. Further, copper losses of the transformer are decreased due to the reduced RMS current of each transformer's winding. Therefore, total losses are minimized and the efficiency of the converter is improved by using the proposed PWM C strategy. Digital signal processor (DSP: TI320LF2407) and a field-programmable gate array (FPGA: EPM7128) board are used to generate PWM patterns for three-phase bridge and clamp MOSFETs. A 500W prototype converter is built and its experimental results verify the validity of the proposed PWM strategies.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.28 no.3
• /
• pp.274-285
• /
• 1992

Among various Power converters, a variable voltage variable frequency (VVVF) three-phase PWM inverter is regarded as most promising power converter due to its capabilities, which permits the control of voltage, frequency and harmonic contents in a single power stage employing only on DC source. As a modulating technique of the PWM inverter, the regular sampling technique has rendered possible the on-line computation and generation of PWM control waveforms with a reasonably high switching frequencies. In this paper, microprocessor based three-phase regular samping PWM inverter with real-time control algorithm and control circuits for driving three phase AC motor has been developed. Harmocic components of PWM waveform were analized theoretically in terms of Bessel function series and then calculated by digital computer and observed with spectrum analyzer.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.66 no.2
• /
• pp.58-62
• /
• 2017

This paper presents a novel prototype of the resonant AC link snubber circuit for the three-phase sinwave soft-switching PWM inverter. In principle, its operating principle is described, and the performance evaluations of the specific instantaneous space voltage modulated three-phase sinewave soft switching PWM inverter incorporating a resonant AC link snubber is illustrated, and evaluated, introducing the specific space voltage vector modulation implementation. It is conferred that the validity of three-phase soft-switching inverter treated here in setup experiment.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.7 no.3
• /
• pp.224-236
• /
• 2002

In this paper, a comparative study on the performance of two-phase and three-phase randomized pulse position PWM scheme for mitigation of audible switching acoustic noise in motor drives is done. In the randomized Pulse Position PW, each of two-Phase or three-phase PWM Pulses is located randomly in each switching interval. Simulation and experimental efforts were executed to investigate the spread effects of Power spectra of inverter output voltage, waveforms of ripple current and audible switching acoustic noise. As results, two-phase RP% scheme is more effective from the viewpoint of switching loss and ease of implementation while the three-phase RPWM scheme is more effective from the viewpoint of the spread effects of power spectra. Also, from the view point of the audible switching acoustic noise in motor drives, two-phase and three-phase RPW schemes are nearly the same.