• Journal of Magnetics
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• v.20 no.2
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• pp.166-175
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• 2015

In this study, we describe the design method of a Brush-less DC (BLDC) motor with delta winding connection. After designing delta winding connection model with the $60^{\circ}$ flat-top region of the Back Electro-Motive Force (BEMF), an ideal current source analysis and a voltage source analysis, with a 6-step control, were conducted primarily employing Finite Element Method. In addition, as a current controller, we considered the Current Regulator with PI controller using Simulink for the comparison of torque characteristics. When the input current is controlled, the switching regions and reference signals are determined by means of the phase BEMF zero-crossing point. In reality, the input current variation depends on the inductance as well as input voltage, and it causes a torque ripple after all. Therefore, each control method considered in this research showed different torque ripple results. Based on the comparison, the causes of the torque ripple have been verified in detail.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2201-2208
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• 2014

In this research, the characteristics of Brush-less DC (BLDC) motor in accordance with winding connection method, both Y-connection and D -connection, has been identified with design methodology simply. BLDC motor has been designed for both winding connections, and their torque analysis has been performed considering ideal current source analysis and voltage source analysis with 6-step control. In addition, to reduce torque ripple of BLDC motor, caused by coil inductance, on voltage source analysis with 6-step control, we have proposed suitable control method which is Phase Advance Control. It is verified that the torque ripple has been decreased by virtue of phase advance control, advancing and widening conduction angle of switching, via performance analysis by Finite Element Analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.3
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• pp.249-255
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• 2017

This paper presents air-gap control according to Y and Delta connections of a double-sided air-gap permanent magnet synchronous motor (DA-PMSM) with independent three-phase structure. In particular, the DA-PMSM used in this study can be applied to low-speed and high-torque applications, such as wind turbines, tidal power generations, and electric propulsion ships, because of its modular stators and a rotor with numerous permanent magnets. Unlike conventional three-phase machines, the DA-PMSM has a symmetrical configuration with double-sided air-gap. Therefore, Y/Delta winding connections and serial/parallel configurations between stator modules are possible. To identify the DA-PMSM operating characteristics, mathematical modeling is analyzed according to the Y/Delta connections. Moreover, air-gap control performances by applying the winding connection methods are verified through experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.587-593
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• 2021

Since 2017, a total of 29 fire accidents have occurred in energy storage systems (ESSs) as of June 2020. The common mode voltage (CMV) is one of the electrical hazards that is assumed to be a cause of those fire accidents. Several cases of CMV that violate the allowable insulation level of a battery section are being reported in actual ESS operation sites with △-Y winding connections. Thus, this paper evaluates the characteristics of CMV. An ESS site was modeled with an AC grid, PCS, and battery sections using PSCAD/EMTDC software. As a result of a simulation based on the proposed model, it was confirmed that characteristics of CMV vary significantly and are similar to actual measurements, depending on the grounding method of the internal transformer for PCS. The insulation level of the battery section may be severely degraded as the value of CMV exceeds the rated voltage in case of a grounding connection. It was found that the value of CMV dramatically declines when the internal transformer for PCS is operated as non-grounding connection, so it meets the standard insulation level.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1137-1140
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• 2014

Faulty electric motors onboard vessels with anomalies in windings or poor insulation are usually repaired at land based workshops and reinstalled in place by crew hands after receiving the repaired motors. Especially for 3 phase induction motors which need Y-${\delta}$ starters with 6 lead wires, it would happen that the polarities of stator windings cannot be well distinguished if the original tags of these wires are erased or not visible clearly, resulting in subsequent damage to the repaired motor due to extreme current flow when the power is given to the motor the stator windings of which are wrongly connected in the polarity. This study proposes an easy way to make correct connection in winding polarities without failures based on the electro-magnetically induced voltages on windings when a slight DC current is supplied to a winding coil by using an analog multi-tester. The proposed method is applied to actual motors and delves into the applicability for polarity discrimination through a few measurements onboard vessels.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.245-246
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• 2015

본 논문에서는 삼중 델타 전원과 새로운 커먼-모드 필터 결선을 통해 스위칭에 의한 고조파를 저감하는 방법을 제안한다. PWM에 의해 생성되는 측대파 고조파(Sideband harmonics) 위상을 분석함으로써, 인터리빙 운전 시 삼중 델타 전원 연결과 제안된 커먼모드 필터가 측대파 고조파 전류를 크게 저감할 수 있음을 보인다. 3개의 고정자 권선을 가지는 영구자석 전동기를 이용하여 제안된 필터의 유효성을 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.3
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• pp.229-236
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• 2008

Recently, multilevel H-bridge inverters have become popular in medium to high power ac drive applications. One of significant advantages of them is low harmonic contents in their input line currents thanks to the transformer with multiple phase-shifted secondary windings. This paper attempts to provide basic guidelines for the design of the phase shifting transformer windings and theoretical analysis of input line current harmonics of H-bridge inverters. The part I provides the derivation of basic relationships between input and output current of the transformer and the relationship between the phase shifting characteristics and design aspects of the transformer.