Yong-Seok Kim

Speed sensorless vector control of an induction motor using an extended Kalman filter

The vector control of an induction motor by speed estimation using an extended Kalman filter (EKF) is described. The rotor speed is regarded as a parameter, and the composite state is composed of the original state and the rotor speed. The EKF is employed to identify the speed of an induction motor and rotor magnetic flux based on the measured quantities such as stator currents and DC link voltage. The estimated speed is used for vector control and overall speed control. The current control is performed in the synchronous rotating reference frame, and the estimated speed information is used for reference frame transformation of the current controller. Computer simulation of the speed control has been carried out to confirm the usefulness of the speed estimation algorithm. The error between the real speed and the estimated speed is within a few RPM even in the low speed range of about 20 RPM.<<ETX>>

On-line estimation of IGBT junction temperature using on-state voltage drop

In this paper, a noninvasive and accurate on-line estimation method for IGBT junction temperature is proposed. To optimize the heat management of IGBTs, it provides accurate information about junction temperature. The proposed method requires a few additional passive circuit components for the estimation and it can be easily incorporated into the conventional gate driver circuit. The proposed method consists of two processes, one is off-line characterization of the IGBT under test and the other one is on-line estimation of junction temperature based on the characterized data. The simulation and experimental results confirm the validity of the proposed estimation method.

A novel ride-through system for adjustable speed drives using common-mode voltage

This paper proposes a novel ride-through system for adjustable-speed drives (ASDs) using common-mode voltage. In the proposed ride-through system, the common-mode voltage inherent in PWM converter-inverter systems is used for charging the energy storage device at normal conditions of source power. That is, charging current can be regulated by the control of common-mode voltage with a small reactor while driving motors. At the whole range of voltage disturbance, from balanced or unbalanced shallow voltage sag to outage, ride-through is successively available with proposed system. Various energy storage devices can be selected according to the applications and two kinds of the charging topology-using inverter side or converter side common-mode voltage-are also available in the proposed system.

A new anti-sway control scheme for trolley crane system

This paper proposes a new vision-sensorless anti-sway control scheme, where the sway angle of the load is estimated with a simple acceleration sensor, which can be equipped on the trolley. The sway of the suspended load is suppressed by adding the damping factor, which is calculated with the estimated sway angle. While conventional electric anti-sway systems need an expensive external vision sensor system, the proposed scheme is easily realized on the trolley speed controller with an acceleration sensor. The effectiveness of the proposed scheme is verified by computer simulation and experiments with a miniature of the trolley crane system.

Electro-mechanical re-adhesion control simulator for inverter-driven railway electric vehicle

In this paper, an electromechanical re-adhesion control simulator is proposed for an inverter-driven railway electric vehicle. The basic characteristics of the re-adhesion phenomenon in electric railway systems is analyzed, and an electromechanical model of the railway system is developed based upon those characteristics. Based on the system model analysis, a electromechanical re-adhesion control simulator is designed. The proposed simulator has a wheel-to-wheel structure, which corresponds to the rail-to-wheel of real railway systems. To evaluate the feasibility of the simulator, experiments of re-adhesion are performed with a simple re-adhesion control algorithm. Experimental results prove that the simulator provides an electrical and mechanical environment similar to real railway electric vehicle systems.

A new vision-sensorless anti-sway control system for container cranes

Most of conventional anti-sway control systems focus on control schemes with a vision system. Because it has many drawbacks such as difficult maintenance and high cost, a new vision-sensorless anti-sway control system for container cranes is proposed in this paper. The proposed system includes a multivariable state feedback anti-sway controller with an integrator, a sway velocity observer, and a sway angle detection method in which an inclinometer is used instead of the vision system. While conventional researches have used a simple pendulum model (single wire rope), the hoist wire rope structure of a real container crane is considered and the motion of the head block (spreader) is analyzed. An elaborate pilot crane is constructed to verify the performance of the proposed system. It is a 1/4-scaled model of a real rail mounted quayside crane. The feasibility and the performance of the proposed system are synthetically verified on the pilot crane. Also, experiments are carried out on the real container crane (rubber tyred gantry crane) in the commercial site to verify the performance of the proposed control system.

Characteristic potential method of noise calculation in semiconductor devices: calculation of 1/f noise in MOS transistors in the ohmic region

The characteristic potential method(CPM), which has been successfully applied to calculate 1/f noise and thermal noise of multi-terminal homogeneous semiconductor resistors, is extended to calculate 1/f noise in inhomogeneous devices such as MOSFETs. The drain 1/f noise current of MOSFETs in the linear region is calculated using the CPM together with the well-known existing 1/f noise sources based on either Hooges empirical model or McWhorters model, and the calculated results are compared with the experimental results. It is shown that the difference of the 1/f noise behaviour between n-MOSFETs and p-MOSFETs in the linear region can be attributed to either the difference in their effective field dependence between the local electron mobility and the local hole mobility near the Si-SiO2 interface in the inversion layer or the difference in degree of Nt(oxide trap density)dependence between the effective electron mobility and the effective hole mobility.