• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.1
• /
• pp.57-65
• /
• 2001

The speed control without a speed sensor is expected strongly to progress reliability, simplicity and cost performance of Induction Motor(I.M) systems. Also, it contributes to expansion of I.M systems into various industrial application fields. This paper investigates a novel speed sensorless control method of I.M considering the secondary resistance identification based on the transientless torque control technique. Especially, this paper aimed at the identification of the secondary resistance simultaneously with speed estimation superposing of sinusoidal flux wave to a constant flux value. Furthermore, the secondary flux with some frequency is controlled independently on torque control. The proposed speed estimation method is derived from a motor circuit equation theoretically and also it can be conducted easily by detecting primary motor currents and primary voltage commands at every sampling time. Some numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter are performed to verify the proposed method.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.9
• /
• pp.900-907
• /
• 2014

This paper proposes a MPC (Model Predictive Control) method for the torque and flux controls of induction motor. The proposed MPC method selects the optimized voltage vector for the matrix converter control using the predictive modeling equation of the induction motor and cost function. Hence, the reference voltage vector that minimizes the cost function of the torque and flux error within the control period is selected and applied to the actual system. As a result, it is possible to perform the torque and flux control of induction motor using only the MPC controller without a PI (Proportional-Integral) or hysteresis controller. Even though the proposed control algorithm is more complicated and has lots of computations compared with the conventional MPC, it can perform torque ripple reduction by synthesizing voltage vectors of various magnitude. This feature provides the reduction of amount of calculations and the improvement of the control performance through the adjustment of the number of the unit vectors n. The proposed control method is validated through the PSIM simulation.

• Korean Journal of Optics and Photonics
• /
• v.23 no.1
• /
• pp.1-5
• /
• 2012

According to the paraxial diffraction theory, diffractions of optical systems which have the same wavelength and numerical aperture are always the same, independent of lateral magnification. But the diffractions for optical systems with different magnifications are varied due to the non-paraxial diffraction effect on the imaging of high NA optics. In this study, the non-paraxial diffraction effect is interpreted as a phenomena caused by curved principal planes. Pupil functions and modulation transfer functions of aplanatic conic mirrors are examined as a function of lateral magnification.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.207-211
• /
• 2004

The performance of an inductive position sensor has approved by previous research papers. In this paper, magnetic circuit model of a ring-type multi-pole insuctive position sensor is described. The magnetic circuit model is required to design in ductive position sensor as well as draw a fault tolerance algorithm. Using the magnetic circuit theory, we derived the relationship between voltage applied and flux density in the normal air-gap. By idealizing the modulation/demodulation processes of signal processing circuit, sensor gain with respect to change of displacement is theoretically calculation using the magnetic circuit model, which validate the theoretical derivation.

• Journal of Astronomy and Space Sciences
• /
• v.15 no.1
• /
• pp.59-64
• /
• 1998

Kim & Beuermann (1995, 1996)have developed a model for the propagation of X-rays from the accreting white dwarfthrough the infalling material and the re-emission of the energy deposited by photo-absorption in the optical (and UV) spectral range. By using this model, we calculate the profiles of the $H_{\gamma}$ emission-line spectrum of intermediate polars. Photoabsorption of X-ray by the infalling material is the dominant process in forming the observed energy-dependent rotational modulation of the X-ray flux. X-ray and optical modulations are sensitive to model parameters in different ways. In principle, these dependencies allow us to obtain improved insight into the accretion geometry of the intermediate polars. We present results of our calculations and compare them with the $H{\beta}$ line spectrum(Kim & Beuermann 1996).

• International Journal of Control, Automation, and Systems
• /
• v.4 no.1
• /
• pp.113-123
• /
• 2006

In this paper, an improved direct torque control (DTC) method for sensorless matrix converter drives is proposed which enables to minimize torque ripple, to obtain unity input power factor, and to achieve good sensorless speed-control performance in the low speed operation, while maintaining constant switching frequency and fast torque dynamics. It is possible to combine the advantages of matrix converters with the advantages of the DTC strategy using space vector modulation and a flux deadbeat controller. To overcome the phase current distortion by the non-linearity of a matrix converter drive, the simple non-linearity compensation method using PQR power theory are presented in the proposed scheme. Experimental results are shown to illustrate the feasibility of the proposed strategy.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.466-470
• /
• 1997

This paper forcuses on methods of achieving a direct vector control of induction motors for an electric vehicle based on a closed-loop flux observer. Also over-modulation topology and maximum torque per ampere over the entire field weakening region have been implemented. The proposed scheme is verified through the simulation and the experiment using the chassis dynampmeter and road load driving test for the induction motor controller and the electric vehicle system.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.1042-1045
• /
• 2000

Speed control without speed sensor is expected strongly to progress reliability, simplicity and cost performance of I.M and to expand its application part. This paper investigates a novel speed estimation method of I.M considering the secondary resistance identification based on the transientless torque control technique. Especially, this paper aimed at the identification of the secondary resistance simultaneously with speed estimation. For this, the secondary flux with some frequency is controlled independently on torque. The proposed speed estimation method is derived from a motor circuit equation theoretically and also it can be conducted easily by detecting primary motor currents and primary voltage commands at every sampling time. Some numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter and experimental results are performed to verify the proposed method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.12
• /
• pp.1297-1305
• /
• 2001

In this study, existing control methods that are suggested or applied until now are classified by control parameters, and stability of in the room and floor surface temperatures of each control method is compared through experiments. Then, the control performance of these control methods are analyzed to evaluate the applicability to Korean apartment housing. From the result of the applicability analysis, the outdoor reset with on/off PWM control is found to be desirable for district heating systems and flux modulation is found to be applicable for decentralized heating systems. In the case of independent control systems for each room, on/off PWM control is desirable.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.4
• /
• pp.263-270
• /
• 2021

Active AC/DC converters with PWM operation are utilized to regulate rectified DC bus voltage of a permanent magnet synchronous generator in the maritime DC power system. A DC bus voltage regulation strategy that exploits the six-step operation is proposed in this study. Compared with that of the PWM operation, switching loss of the converter can be significantly reduced under the six-step operation. Moreover, conduction loss can also be reduced due to the high modulation index and reduced flux-weakening current of the six-step operation. A controller is used for the proposed DC bus voltage regulation strategy to verify its validity with the simulation and experimental setup. The simulation and the experimental test results showed that the converter loss reduces to a maximum of 70% and 19%, respectively.