• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.139-141
• /
• 1996

The switched reluctance motors(SRM) are simple and robust in structure. Because the wide range of power and speed, their application field is increasing. In order to design the motors and to evaluate the performance of them properly, an accurate study about the analysis of motor characteristics is required. In this paper, for the analysis of SRM characteristics, the finite element method which is based on the solution of combined equations both the electromagnetic field equations and the circuit equations of stator is adopted. The analysis model is to he assumed two-dimensional and the nonlinear property of magnetic materials is considered by Newton-Raphson method. To verify the usefulness of the proposed algorithm, commercial SRM is chosen and simulated. The computed torques obtained by Maxwell Stress Tensor are compared with the experimental data and it is found that they are in good agreement. By applying the proposed algorithm to two cases, currents of stator and torques at every angular positions of rotor are obtained step by step. Comparing them, one can recognize that torque ripple of SRM can he improved by controlling the switching sequences of driving circuits.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2008년도 하계학술대회 논문집
• /
• pp.265-267
• /
• 2008

As generally recognized, the driving performance of a SRM at higher speed will be degraded due to the effects of back electromagnetic force (EMF). This phenomenon can be improved via voltage boosting. So in this paper an improved converter of enhancing the performance for four-phase switched reluctance motor (SRM) is proposed. By using one additional capacitor and switches, an extra controllable boosted voltage can be produced during the rise and fall periods of a motor phase current. Then this active boosted voltage can reduce the effect of EMF on the current, particularly at high speeds. The attractive features of the proposed converter are as follows: obtaining boosted voltage to improve performance of SRM with same numbers of switch and diode as asymmetric converter, having higher control flexibility and capability of boosting voltage compared with passive boosting converters, possessing lower cost and simple control in comparison with existing active boosting converters. The performances of the proposed circuit are verified by the simulation and experiment results.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제51권8호
• /
• pp.434-440
• /
• 2002

Switched Reluctance Motor (SRM) has been not commonly used because of the severe noise and vibration, although it has many advantages as solidity and economical efficiency. The origin of the acoustic noise and vibration in SRM's can be broadly classified into two types, mechanical and magnetic. Therefore this paper verifies the origin of vibration induced by radial magnetic forces from various experiments, and then studies the relationship between the output and vibration characteristics of SRM according to switch-on and off angles. Acceleration, torque and efficiency is measured by changing switching angles. From the comparison and analysis of the experimental results, a proper switching angle is presented for both satisfying electric performance and reducing vibration.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1641-1644
• /
• 2005

Magnetic actuation utilizes the mechanic torque that is the result of interaction of the current in a coil with an external magnetic field. A main obstacle is, however, that torques can only be produced perpendicular to the magnetic field. In addition, there is uncertainty in the Earth magnetic field models due to the complicated dynamic nature of the field. Also, the magnetic hardware and the spacecraft can interact, causing both to behave in undesirable ways. This actuation principle has been a topic of research since earliest satellites were launched. Earlier magnetic control has been applied for nutation damping for gravity gradient stabilized satellites, and for velocity decrease for satellites without appendages. The three axes of a micro-satellite can be stabilized by using an electromagnetic actuator which is rigidly mounted on the structure of the satellite. The actuator consists of three mutually-orthogonal air-cored coils on the skin of the satellite. The coils are excited so that the orbital frame magnetic field and body frame magnetic field coincides i.e. to make the Euler angles to zero. This can be done using a Neural Network controller trained by PD controller data and driven by the difference between the orbital and body frame magnetic fields.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
• /
• pp.20-24
• /
• 1989

The time optimal position control scheme can be repeatedly taken from the initial state of a dynamic system to a desired one as fast as possible at the industrial drives. In this case, the machine parameters will vary due to temperature, frequency, and saturation effects. In particular, the rotor resistance value changes dramatically with temperature and frequency. These changes affect the command values of the stator current components and slip speed. There is a mismatch between the commanded variables and actual variables of the induction motor drive, and this situation leads to decoupling of the vector controller from the plant, i.e the induction motor. Consequences of such decoupling include the initiation of oscillations of the rotor flux and unsuitable switching of electromagnetic torque of the induction motor servo drive. Therefore, a rotor resistance parameter compensating method for the induction motor is described.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제52권3호
• /
• pp.107-115
• /
• 2003

This paper deals with the effect of the auxiliary pole core in the automotive starter motor on its characteristics. This motor is excited by the permanent magnet and has auxiliary pole core in the stator. The auxiliary pole core is a device to increase the effective flux to obtain the starling torque and prevent the demagnetization of the permanent magnet from the starting current. It Is important to design the auxiliary pore core. And overhang structure causes the electromagnetic phenomenon of 3-dimensional flux Path. Therefore. the characteristic analysis is achieved by the 2-dimensional Finite Element Method (FEM) with the compensated model and the 3-dimensional Equivalent Magnet Circuit Network (3D EMCN). The mechanical loss and the brush and coil resistance are separated from the various experiment of the tested motor, and then these factor are reflected on the analysis results. The validity of the proposed analysis method is verified by comparing the experimental and analysis results. The effects of the design parameters related to the auxiliary pole cote on the motor performance are analyzed by the proposed method.

• Journal of Power Electronics
• /
• 제11권4호
• /
• pp.430-438
• /
• 2011

This article proposes a robust nonlinear control based on Lyapunov's redesign, whose purpose is to deal with parametric uncertainty in the resistance of the motor windings. The robust controller design is based on the passivity properties of the motor, as well as energy shaping and damping injection. The application of this control technique is focused on electric vehicles mainly formed by a battery bank, a power inverter, an AC brushless motor and the mechanical transmission. The sine PWM technique is used to trigger the switching devices of inverter. The results were obtained from simulation, where is shown that robust control makes a proper tracking of electromagnetic torque.

• 대한기계학회논문집A
• /
• 제25권9호
• /
• pp.1341-1349
• /
• 2001

In this paper, 3 D.O.F. actuator, which has three degrees of freedom in one joint, is proposed. The proposed 3 D.O.F. spherical actuator is composed of the rotor and atator. The upper plate of the stator supports the rotor and five electromagnets are located at the base of the stator. The rotor has two permanent magnets, and each rotational axis of the rotor gimbal system is supported by the bearing. To find out the governing equations for the torque generation, Coulombs law and Lorentz force with respect to magnetism is applied. As the experimental results, if the distance between electromagnet and permanent maget is far enough, the force between these magnets can be expressed from current of coils and z-axial distance. For the purpose of control 3 D.O.F. actuator, PID control law is applied. The experimental results are presented to show the validity of the proposed 3 D.O.F. actuator.

• Journal of Magnetics
• /
• 제22권2호
• /
• pp.203-213
• /
• 2017

Magnetically suspended control & sensitive gyroscope (MSCSG) is a novel type of gyroscope with the integration of attitude control and attitude angular measurement. To improve the precision and reduce the power consumption of Lorentz Force-type Magnetic Bearing (LFMB), the air gap flux density distribution of LFMB has been studied. The uniformity of air gap flux density is defined to qualify the uniform degree of the air gap flux density distribution. Considering the consumption, the average value of flux density is defined as well. Some optimal designs and analyses of LFMB are carried out by finite element simulation. The strength of the permanent magnet is taken into consideration during the machining process. To verify the design and simulation, a high-precision instrument is employed to measure the 3-dimensional magnetic flux density of LFMB. After measurement and calculation, the uniform degree of magnetic flux density distribution reaches 0.978 and the average value of the flux density is 0.482T. Experimental results show that the optimal design is effective and some useful advice can be obtained for further research.

• Journal of Electrical Engineering and Technology
• /
• 제13권4호
• /
• pp.1586-1595
• /
• 2018

For the problem that the complexity of 3-D modeling and multi parameter optimization, as well as the uncertainty of the winding factor of axial flux permanent magnet generator with coreless windings. The complex 3-D model was simplified into 2-D analytic model, and an analytical formula for the winding factor that adapting different coreless stator winding is proposed in this paper. The analytical solution for air-gap magnetic fields, no-load back EMF, electromagnetic torque, and efficiency are calculated by using this method. The multiple objective and multivariable optimization of the maximum fundamental and the minimum harmonic content of back EMF are performed by using response surface methodology. The proposed optimum design method was applied to make a generator. The generator was tested and the calculated results are compared with the proposed method, which show good agreements.