• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.224-234
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• 2008

Multi-phase machines can be used in variable speed drives. Their applications include electric ship propulsion, 'more-electric aircraft' and traction applications, electric vehicles, and hybrid electric vehicles. Multi-phase machines enable independent control of a few numbers of machines that are connected in series in a particular manner with their supply being fed from a single voltage source inverter(VSI). The idea was first implemented for a five-phase series-connected two-motor drive system, but is now applicable to any number of phases more than or equal to five-phase. The number of series-connected machines is a function of the phase number of VSI. Theoretical and simulation studies have already been reported for number of multi-phase multi-motor drive configurations of series-connection type. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information concerning the rotor speed is extracted from measured stator currents and voltages at motor terminals. Open-loop estimators or closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an MRAS estimator based sensorless control of a vector controlled series-connected two-motor five-phase drive system with current control in the stationary reference frame. Results, obtained with fixed-voltage, fixed-frequency supply, and hysteresis current control are presented for various operating conditions on the basis of simulation results. The purpose of this paper is to report the first ever simulation results on a sensorless control of a five-phase two-motor series-connected drive system. The operating principle is given followed by a description of the sensorless technique.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.500-504
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• 1997

Current source inverter drives of auto sequentially commutated type are very popular in high power applications, because of simple power circuit configuration with four quadrant operation. But the six-step current output create harmonic problems and the input power factor of such a drive is not always good. In this respect pulse width modulated drives using gate turn off thyristors ( GTO ) are finding application, especially in traction drives. However the switching and snubber loses of a GTO do not permit the inverter switching frequency go beyond a few hundred hertz.This will again introduce low frequency harmonic problems. Multi level inverters of the 3-level and 5-level can be considered as an alternative to overcome the low switching frequency harmonic problem of the 2-level GTO inverters. But with multi level inverters the complexity of the power circuit increases. In this paper a combination of multi level ( 2-level and 3-level ) inverters and multi phase induction motor ( 3-phase and 6-phase) configurations are presented for high power VSI drives for traction applications with reduced inverter switching frequency requirements coupled with reduced voltage rating for the power switch.

• 대한전기학회논문지
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• 제36권8호
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• pp.539-546
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• 1987

In case of operating at Variable speed the induction motor by a frequency transformer, it will cause ripples in motor torque and considerably bad effects on the machines because the output side of the frequency transformer involves a great number of harmonics. This paper Presents the methods of decreasing torque ripples in induction motor and of improving current waveform, by means of forming the waveforms of output current into multi-step waveforms similiar to sinusoid, and also by means of eliminating the harmonic components maximally, in case of operating a 18-phase multi-inverter combining 3-step current source inverter.

• 전기학회논문지
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• 제56권12호
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• pp.2127-2134
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• 2007

The simulation model has been already developed not for 7 phase but for 3 phase BLDC motor. It is necessary to develop a new simulation model of multi-phase BLDC motor including the phase delay angle especially in the high speed region. In this paper, the suitability of the proposed model is verified through the several computer simulations, and experimented results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.742-745
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• 2005

This paper describes a simple pseudo-random carrier modulation technique for the acoustic noise reduction of the three phase multi-level inverter based motor drives. The proposed method generates a new pseudo-random carrier by randomly synthesizing a carrier with fixed frequency and a carrier with opposition phase. To confirm the validity of the proposed method, a 130v three-phase multi-level inverter was Implemented and tested. The experimental results show that the output line voltage and acoustic noise harmonics spectra of an inverter have broadening effect of harmonics, as only simple synthesis of fixed frequency carries.

• 조명전기설비학회논문지
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• 제22권12호
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• pp.64-70
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• 2008

종래의 준 랜덤 주파수 캐리어(PRC : Pseudo-Randomized Frequency Carrier) 변조기법을 3상 H-브리지 멀티레벨 인버터(HBML: H-Bridge Multi-Level Inverter)에 적용하는 경우, 스위칭 주파수의 2배 주파수 영역에서 큰 스펙트럼 클러스터가 그대로 존재하는 문제점이 있다. 본 연구에서는 서로 2배의 주파수 비율을 갖는 2개의 고정주파수 삼각파 캐리어와 3단계 멀티플렉서(MUX : Multiplexer)를 이용하여 종래의 PRC기법의 고조파 스펙트럼 확산 효과를 개선하였다. 제안된 기법은 1.5[kw]급 3상 HBML인버터 구동시스템에 적용하였으며, 종전의 방법과 제안된 방법의 전압 및 전류 고조파 스펙트럼을 비교 검토하였다.

• 전력전자학회논문지
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• 제20권1호
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• pp.38-44
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• 2015

This paper presents the sensorless drive method for mono inverter dual parallel (MIDP) surface mounted permanent magnet synchronous motor (SPMSM) drive system. MIDP motor drive system is a technique that can reduce the cost of the multi motor driving system. To maximize this merit of the MIDP motor drive system, the sensorless technique is essential to eliminate the position sensors. This paper adopts an appropriate sensorless method for MIDP SPMSM drive system, which uses the reduced order observer and phase locked loop (PLL) to reduce the calculation burden. The I-F control method is implemented for start-up and low speed operation. The validity and performance of the proposed algorithm are shown via experiments with 600-W SPMSMs.

• 전력전자학회논문지
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• 제4권5호
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• pp.413-422
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• 1999

Auto-connected multipulse(12/24pulse) rectifier schemes are cost effective methods for reducing line current hamonics in PWM drive systems. Employing these schemes to enhance utility power quality requires careful attention to several design considerations In particular, excursion of dc-link voltage at no load, effect of pre-existing voltage distortion, impedance mismatches, unequal diode drops on rectifier current sharing and performance, are fully analyzed, Several corrective measures to improve the performance of 12/24­pulse rectifier systems are also discussed. Finally, experimental results on a 460V, 60Hz 400kVA commercial ASD, retrofitted with 12/24pulse rectifier systems are discussed in detail.