• 한국전기전자재료학회논문지
• /
• 제23권5호
• /
• pp.408-412
• /
• 2010

The single-phase switched reluctance motor(SRM) generates the positive torque in the restricted section. So, it can not started by itself and the torque ripple is heavier than poly-phase. For self-starting and fixing rotating direction, the rotor should be placed at the rising inductance slope when stationary. The parking permanent magnet locates the rotor in the fixed position, which can be started by it-self. It is very simple and cost effective but has some drawbacks. It affects the rotor during the operation, so the characteristics of motor, such as a torque, speed, and ripple are changed to go bad. This paper presents the detent torque of parking magnet starting device through the finite element analysis and experiments. The finite element analysis is performed at incremental rotor positions over one detent torque cycle for any one pole. The prototype, fabricated in the previous research, is used for the experiments. The inductance, instant torque, and detent torque are calculated using the terminal voltage and phase current. Finally, the finite element analysis result and the experiment result are compared for analysis and validity.

• 에너지공학
• /
• 제29권1호
• /
• pp.34-43
• /
• 2020

풍력발전기 로터의 저속운전 가능성에 대해 기동토크를 평가하고자 하였다. 본 연구에서 살펴본 저속시동 가능성의 날개는 초임계에어포일을 보완하여 AMI계열(AMI903 및 AMI904)의 날개를 제안하여 공력성능을 유지하며 제작상 및 유지보수의 어려움을 제거하였다. 따라서 본 연구는 FLUENT를 이용하여 난류유동 해석을 통해 제안된 날개의 받음각(-180°~+180°)에 대한 항력계수와 양력계수를 제시하였으며, 이 값들로부터 정지하고 있는 날개의 회전 위치에 따른 접선방향의 토크계수를 정의하여 제시하였다. 기동력의 크기와 방향을 결정할 토크계수는 대부분 양의 값(반시계방향)으로 나타났으며 특별히 받음각이 0°에서 180° 및 -90°에서 -180°에서 양의 값이며 0°에서 -90°에서 매우 작거나 음의 값을 나타냈다. 한편 기동토크는 두께가 얇은 AMI903보다 두꺼운 AMI904에서 더 큰 것으로 나타났다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2015년도 제46회 하계학술대회
• /
• pp.682-684
• /
• 2015

A 12/14 bearingless switched reluctance motor (BLSRM) with hybrid stator poles has been proposed due to the outstanding decoupling characteristics between the torque and suspending force. However, the motor is a two-phase motor. The output torque of the motor has torque dead zone and high torque ripple. Hence, the motor cannot self-start at some rotor positions. To solve the self-starting problems and reduce the torque ripple, a stepped rotor is proposed in this paper. Then, the motor with the stepped rotor is optimally designed. In the new designed motor, the majority parameters are kept the same with those of original motor; only the torque pole arc and rotor pole shape are optimally designed. The characteristics of the redesigned motor, such as inductance, torque and suspending force, are analyzed and compared with those in the original motor. Finally, the effectiveness of the proposed method is verified by the simulation results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 B
• /
• pp.959-961
• /
• 2004

A multi pole SRM(switched reluctance motor) is applied by the regulated current in regular sequence. So, it can be started by itself. But a single phase SRM can not be started by itself because the positive torque is only generated in the limited zone which the inductance is increased. Therefore, it is required auxiliary device for self starting which place the rotor in start position. The prototype was designed and fabricated in the previous research. It has the permanent magnet, which is installed in the bottom of the rotor, for self starting. But the permanent magnet affect the prototype during operation and cause the decrease of the torque and speed. The influence of the permanent magnet on the average torque and speed was already confirmed. On this paper, the instant torque of the prototype was calculated from the experiment results which is the inductance and current according to installed permanent magnet or not.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제6권2호
• /
• pp.257-268
• /
• 2014

In this study, flow-driven rotor simulations with a given load are conducted to analyze the operational characteristics of a vertical-axis Darrieus turbine, specifically its self-starting capability and fluctuations in its torque as well as the RPM. These characteristics are typically observed in experiments, though they cannot be acquired in simulations with a given tip speed ratio (TSR). First, it is shown that a flow-driven rotor simulation with a two-dimensional (2D) turbine model obtains power coefficients with curves similar to those obtained in a simulation with a given TSR. 3D flow-driven rotor simulations with an optimal geometry then show that a helical-bladed turbine has the following prominent advantages over a straight-bladed turbine of the same size: an improvement of its self-starting capabilities and reduced fluctuations in its torque and RPM curves as well as an increase in its power coefficient from 33% to 42%. Therefore, it is clear that a flow-driven rotor simulation provides more information for the design of a Darrieus turbine than a simulation with a given TSR before experiments.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
• /
• pp.813-814
• /
• 2006

The squirrel case induction motor has widely used in the driving of the blowers but it is low efficiency and hard to control. So, the damper is used for the control of a flow and it cause to low the driving efficiency. Our laboratory has proposed the single-phase SRM(switched reluctance motor) for driving blowers. It has salient pole structure and can be reduced a number of semiconductors than three-phase SRM. But it can not be starting by itself and has heavier torque ripple than three-phase SRM. For self-starting the single-phase SRM is required the starting device which place the rotor at the rising inductance slope. On this paper, the electromagnet starting device is designed to generate the starting torque and to fix the rotating direction of the single-phase SRM which is fabricaed to use a blower.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2004년도 학술대회지
• /
• pp.220-224
• /
• 2004

The present paper deals with the numerical study to analyze the self-starting performance of impulse turbine in a reciprocating air flow generated by sinusoidal motion of wave inside oscillating water column. Result was compared to that of Wells turbine, well-known wave energy conversion device, and showed that the impulse turbine has a superior self-starting ability. More detailed parametric study was performed to demonstrate the effects of moment of inertia of rotor, loading torque, tip clearance and angle of guide vane.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2007년도 하계학술대회 논문집
• /
• pp.226-228
• /
• 2007

SRM drive systems are designed to meet operating standards such as low cost, constant torque independent of rotor position, a desired operating speed range, high efficiency, and high performance. In applications using small motors, low cost and high performance with self-starting capabilities are highly desired. This paper discusses a novel two phase SRM (TPSRM) that has high performance characteristics with self-starting capability, low manufacturing cost with a two phase inverter and simple magnetic structure, and high efficiency. The principle of operation, analysis, and simulation for design are presented. The machine design is verified using finite element analysis (FEA) software. Analysis and simulation results are given to validate the TPSRM design.

• 한국안전학회지
• /
• 제14권2호
• /
• pp.52-61
• /
• 1999

This paper proposes the application of fuzzy control for high performance control of induction motor using electric vehicles. A fuzzy controller converts a set of liguistic rules based on expert knowledge into a automatic control strategy. Such controllers have often been found superior to conventional controllers especially when information being processed is inexact and uncertain. A system with fast torque response is very beneficial in applications where direct self control (DSC) is highly desirable. The response of DSC is slower during startup and during change in command torque. Fuzzy control is used for implementation of DSC to improve its slow response. Simulation implementation of the fuzzy logic controller was carried out to verify the behavior of the controller. The simulation results with fuzzy control are compared with those of the conventional DSC. The starting flux and torque response and the responses to the step changes in command torque with fuzzy implementation show a considerable improvement over the conventional control. The steady state responses in both the cases are the same.

• Wind and Structures
• /
• 제25권6호
• /
• pp.551-567
• /
• 2017

Studies of unsymmetrical blade H-Darrieus rotors at low wind speeds in terms of starting time, static torque, and power performances for different blade parameters: thickness-to-chord (t/c), camber position, and solidity are scarce. However these are required for knowing insights of rotor performances to obtain some design guidelines for the selection of these rotors. Here, an attempt is made to quantify the effects of these blade parameters on the performances of three different H-Darrieus rotors at various low wind streams. Different blade profiles, namely S815, EN0005 (both unsymmetrical), and NACA 0018 (symmetrical blade for comparison) are considered. The rotors are investigated rigorously in a centrifugal blower apparatus. Firstly the dynamic and static performances of the rotors are evaluated to determine the best performing rotor and their optimum solidity. Generalised performance equations are developed based on selected blade parameters which are validated for the unsymmetrical rotors. Further, the starting time is quantified with respect to the rotor inertia to determine the suitable range of inertia that helps the unsymmetrical blade rotor to self-start earlier than the symmetrical one. This study can work as a benchmark for the selection of optimum blade parameters while designing an unsymmetrical blade rotor at low wind speeds.