Jun-Keun Ji

DSP-based self-tuning IP speed controller with load torque compensation for rolling mill DC drive

This paper describes the design and the implementation of a self-tuning integral-proportional (IP) speed controller for a rolling mill DC motor drive system, based on a 32-bit floating point digital signal processor (DSP)-TMS 320C30. To get a better transient response than conventional proportional-integral (PI) and/or integral-proportional (IP) speed control in the presence of transient disturbance and/or parameter variations, an adaptive self-tuning IP speed control with load torque feedforward compensation was used. The model parameters, related to motor and load inertia and damping coefficient, were estimated online by using recursive extended least squares (RELS) estimation algorithm. On the basis of the estimated model parameters and a pole-placement design, a control signal was calculated. Digital simulation and experimental results showed that the proposed controller possesses excellent adaptation capability under parameter change and a better transient recovery characteristic than a conventional PI/IP controller under load change. >

Torsional vibration suppression control in 2-mass system by state feedback speed controller

In this paper, observer-based state feedback speed controller for torsional vibration suppression of a 2-mass system is proposed. Because of the difficulty of measuring the load speed and the shaft torque in real plant, the reduced observer is used to estimate not only the unknown states but also the load torque disturbance. Simulations and experiments carried out to verify this algorithm in comparison with conventional PI controller. This controller shows better command following characteristic without torsional vibration. The speed response to the rapid load torque change is also examined to show the disturbance rejection characteristic which is specially important in industrial applications such as rolling mill drives. At the moment of impact load, the speed drop is reduced and the recovery time is shortened remarkably.<<ETX>>

LQG based speed controller for torsional vibration suppression in 2-mass motor drive system

In this paper, an LQG based speed controller for torsional vibration suppression in a 2-mass motor drive system is proposed. Because of the difficulty of measuring the load speed and the shaft torque, the Kalman filter as an optimal full order estimator is used. The Kalman filter can also estimate the load torque disturbance as well as unknown states. The details of the determination of the control parameters of a LQG based speed controller with load torque feedforward compensation is explained, and how the control response is affected based on the selection of each weighting in the performance index is also considered. Simulations are carried out to verify this algorithm in comparison with a conventional PI controller.<<ETX>>

Operation analysis and new current control of parallel connected dual converter system without interphase reactors

In this paper, a predictive current control scheme for a twelve-pulse parallel connected dual power converter system without interphase reactors (IPR) is presented. Firstly, the characteristics of system without IPR are analyzed and compared with that of system with IPR. And the predictive current control of this system is discussed. Finally the validity of the presented system and the excellence of the predictive current control response is proved through the simulation results and experimental results.

Test of an induction motor with HTS wire at end ring and bars

Motors with HTS wires or bulks have been developed recently. These are a large synchronous motor with HTS wires at the field winding in the rotor, hysteresis and reluctance motors with HTS bulk in the rotor. This paper presents the fabrication and test results of an HTS induction motor. Conventional end rings and short bars were replaced with HTS wires in the motor. Stator of the conventional induction motor was used as the stator of the HTS motor. Rated capacity and rpm at full rotor of the conventional motor were 0.75 kW and 1710 rpm. Two HTS wires are used in parallel to make the end rings and bars. The critical current of the BSCCO-2223 HTS wire which was used in the bars and end rings were 115 A. An electrodynamometer was coupled directly to the shaft of the rotor with HTS wires.

Analysis of Estimation Errors in Rotor Position for a Sensorless Control System Using a PMSM

In a sensorless control system with a Permanent Magnet Synchronous Motor (PMSM), the angular position of the rotor flux can be estimated by a voltage equation. However, the estimated angle may be inaccurate due to various causes. In this paper, it was comprehensively analyzed how various causes affect the angle error. As a result of the analysis, an error equation intuitively describing these relationships was derived. The parameter errors of a PMSM and the non-ideal properties of the driving system were identified as error-causing factors. To demonstrate the validity of the error equation, PMSMs were tested at various operating points. The variations in angle errors could be well explained with the error equation.

DSP-based self-tuning IP speed controller and predictive current controller for rolling mill DC drive

This paper describes the implementation of self-tuning integral-proportional (IP) speed controller and predictive current controller for a rolling mill DC motor drive system, which uses the Texas Instrument TMS 320C30 digital signal processor (DSP) chip. With the predictive current control algorithm, the response of the system is improved significantly and the excellent dynamic response is also guaranteed over the whole operating conditions including discontinuous current and current reversal. Digital simulation and experimental results show that proposed controllers possess excellent adaptation capability as well as transient recovery under load changes.<<ETX>>

Novel topology of a line interactive UPS using PQR instantaneous power theory

This work proposes a novel topology and control algorithm for a three-phase line-interactive UPS system with active power-line conditioning capability. This paper presents a simple and systematic control algorithm to regulate the source current and the load voltage of the proposed UPS system using PQR transformation. A parallel inverter operating as a controlled voltage source regulates the source current sinusoidal by controlling the applied voltage on an AC line inductor. The series inverter operating as a dynamic voltage restorer (DVR) compensates for the main source voltage and rides through the output load voltage to be balanced and harmonic-free. Both of the series and parallel inverters always act as controllable voltage sources independently, so that the three-phase output voltages can transfer seamlessly between normal mode and backup mode. The proposed UPS system has high operation efficiency and high usage of the converter capacity, and good endurance against voltage transients or EMI noise resulted from the mains. The feasibility of the proposed UPS system has been investigated and verified through computer simulations and experiments by a 60 kVA prototype UPS.

A novel three-phase line-interactive UPS system with parallel-series active power-line conditioning capabilities using AC line reactor

In this paper a novel three-phase line-interactive UPS system with parallel-series active power-line conditioning capability using AC line reactor and two four-leg voltage source converter (VSC) is proposed. The four-leg VSC can use the DC-link voltage effectively by the 3-D SVPWM method. Hence the DC battery voltage can be reduced by 15% in comparison to that of the conventional line-interactive UPS system. The parallel inverter operating as a shunt active filter is a controlled voltage source and controls the three-phase line voltage independently in order to control the source current. It eliminates the neutral line current and the active ripple power of the source side using the dqo transformation so that unity power factor and the sinusoidal source current can be achieved even though both the source and the load voltages have zero sequence components. The series inverter operating as dynamic voltage restorer (DVR) compensates the load voltage and allows it to be balanced and harmonic-free. Both of the series and shunt inverters always act as independently controllable voltage sources, so that the three-phase output voltage can show a seamless transition to the backup mode. The feasibility of the proposed UPS system has been investigated and verified through experimental results.

DSP-based self-tuning IP speed controller for rolling mill DC drive

This paper describes the design and the implementation of a self-tuning integral-proportional(IP) speed controller for a rolling mill DC drive system, based on a 32 bit floating point Digital Signal Processor TMS 320C30. To get a better transient response than conventional proportional-integral(PI) and/or integral-proportional (IP) speed control, an adaptive self-tuning IP speed control with load torque feedforward compensation was used in the presence of transient disturbance and/or parameter variations. The model parameters, related to motor and load inertia and damping coefficient, were estimated on-line by using a recursive extended least squares (RELS) estimation algorithm. On the basis of the estimated model parameters and a pole-placement design, a control signal was calculated. Digital simulation and experimental results showed that the proposed controller possesses excellent adaptation capability under parameter change and better transient recovery characteristic than conventional PI/IP controller under load change.<<ETX>>