Sang-Uk Kim

Implementation of a speed sensor-less vector control of induction motor by reduced-order extended Kalman filter

The extended Kalman filter (EKF) has been known to be correctly capable of estimating system parameters and state variables by eliminating virtually all influences of structural noise in the field-oriented control scheme for induction motors. This paper presents a design method of a reduced-order extended Kalman filter which consists of rotor speed and flux estimation only by measuring stator currents. The proposed method has some advantages of saving computation time in comparison with the full-order extended Kalman filter. For the noise reduction, robust speed sensorless vector control is realized in the thesis. Experimental results show the effectiveness of the control strategy proposed here for induction motor drives.<<ETX>>

Robust TDOF controller of induction motor without speed sensors for variations of rotor resistance

This paper describes the speed sensorless vector control of an induction motor using two degrees of freedom (TDOF) theory. A TDOF control design which robustly stabilizes the plant, guarantees robust H/sub /spl infin// performance in terms of a feedback controller and has a good tracking performance in a feedforward controller is presented. In this paper, an induction motor drive control system which is robust to variations of rotor resistance and improves the tracking performance is constructed. An adaptive flux observer is used for the purpose of estimating rotor flux and speed in the speed sensorless scheme. Experimental studies verified the validity of the proposed algorithm.

Acoustic Noise and Vibration Reduction of Coreless Brushless DC Motors with an Air Dynamic Bearing

This paper presents the acoustic noise and mechanical vibration reduction of a coreless brushless DC motor with an air dynamic bearing used in a digital lightening processor. The coreless brushless DC motor does not have a stator yoke or stator slot to remove the unbalanced force caused by the interaction between the stator yoke and the rotor magnet. An unbalanced force makes slotless brushless DC motors vibrate and mechanically noisy, and the attractive force between the magnet and the stator yoke increases power consumption. Also, when a coreless brushless DC motor is driven by a 120° conduction type inverter, high frequency acoustic noise occurs because of the peak components of the phase currents caused by small phase inductance and large phase resistance. In this paper, a coreless brushless DC motor with an air dynamic bearing to remove mechanical vibration and to reduce power consumption is applied to a digital lightening processor. A 180° conduction type inverter drives it to reduce high frequency acoustic noise. The applied methods are simulated and tested using a manufactured prototype motor with an air dynamic bearing. The experimental results show that a coreless brushless DC motor has characteristics of low power consumption, low mechanical vibration, and low high frequency acoustic noise.

A Study on the MAC(Media Access Control) protocol for Unmanned Aerial Vehicle(UAV)

In this paper, we studied on MAC(Media Access Control) protocol for UAVs application. According to the number of UAVs, ground control station should control properly increased UAVs. So, we applied CSMA/CA that used in current civil aircraft to UAV communications and verified the applicability through comparison of throughput and delays of data with various message sizes, In the results, we confirmed applicability for UAVs MAC protocol.

A Study on the Improvement of MIMO Antenna Isolation for Mobile Applications

In this paper, neutralization line structure have been employed to improve the isolation between the MIMO antenna system. The proposed MIMO antenna size is 116 mm × 64 mm × 5 mm and designed on FR-4(er = 4.4) ground substrate. Neutralization line was applied to enhance isolation between the each antenna eleme nts. The fabricated antenna satisfied a VSWR below 3 in LTE band B13 and the isolation between the MIMO antenna system is presented below -15dB. On the H-plane, antenna shows an omnidirectional pattern. In LTE band B13, the antenna presents a gain of a -2.6dBi ∼-1.18dBi and radiation efficiency of 33.49% ∼ 46.45%. Comparing measurement result with the outcome of simulation, the proposed MIMO antenna is expected to be applied for mobile application.

A sensorless vector control of the saturated induction motor using third harmonic voltages

A compensation method of the inductance variations for the speed sensorless control of a saturated induction motor using third harmonic voltages is presented. The air-gap flux of the saturated induction motor contains the space harmonic components rotating synchronous frequency. As a function of the air-gap flux saturation, the dominant third harmonic voltage is used to compensate the nonlinear variations of the mutual inductance depending on the saturation level of the motor. One can measure the amplitude of the space harmonic voltage by using a new method of measurement and compensation scheme. Under the saturated condition, the rotor flux observer for the speed sensorless control is designed using the inductance adaption scheme. The validity of the proposed compensation scheme in the speed sensorless control using rotor flux observer is verified by simulations.

Binary observer for speed sensorless vector control of induction motors

Field oriented control methods have been used for design techniques in variable speed induction motor drives. This paper describes a binary observer which includes the rotor flux and speed estimations for induction motor drives. Sliding observers, based on the variable structure control theory, have been known to be applied for optimal pole assignment to maintain insensitivity to parameter variations and ensure the stability of the identifier. Sliding observers, however, possess high frequency chattering which deteriorates the state estimation performance. To reduce the chattering on the sliding surface in an adaptive sliding observer and improve the estimation performance, a binary control scheme which has main advantages of the absence of high-frequency chattering and finite gains is applied in this paper. Experimental results show the effectiveness of the proposed binary observer for the sensorless speed control of induction motor drives.