• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.57-64
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• 2007

In the recent years, development of machine tool with high speed feeding system have brought a rapid increase in productivity. Practically, thermal deformation problem due to high speed is, however, become a large obstacle to realize high precision machining. In this study, therefore, the construction of automatic error compensation system to control thermal deformation in high speed feeding system with real time is proposed. To attain this purpose, high speed feeding system with feeding speed 60mm/min is developed and experimental equation for relationship between thermal deformation and temperature of ball screw shaft using multiple regression analysis is established. Furthermore, in order to analyze thermal deformation error, compensation coefficient is determined and thermal deformation experiments is carried out. From obtained results, it is confirmed that automatic error compensation system constructed in this study is able to control thermal deformation error within $15{\sim}20{\mu}m$.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.175-182
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• 2000

In this paper, a novel speed control strategy using an acceleration feedforward compensation by the estimation of the system inertia is proposed. With the proposed method, the enhanced speed control performance can be achieved and the speed response against the disturbance torque can be improved for the vector-controller induction motor drive systems in which the bandwidth of the speed controller cannot be made large enough. The experimental results confirm the validity of the proposed strategy.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.3
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• pp.154-161
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• 2005

This paper proposes a speed-sensorless induction motor control system using a rotor speed compensation. To explain the proposed system, this paper describes an induction motor model in the synchronous reference frame for the vector control. The rotor flux is estimated by the rotor flux observer using the reduced-dimensional state estimator technique. The estimated rotor speed is directly obtained from the electrical frequency, the slip frequency, and the rotor speed compensation with the estimated q-axis rotor flux. The error of the rotor time constant is indirectly reflected in the rotor speed compensation using the compensation of the flux error angle. To precisely estimate the rotor flux, the actual value of the stator resistance, whose actual variation is reflected, is derived. An implementation of pulse-width modulation (PWM) pulses using an effective space vector modulation (SVM) is briefly mentioned. For fast calculation and improved performance of the proposed algorithm, all control functions are implemented in software using a digital signal processor (DSP) with its environmental circuits. Also, it is shown through experimental results that the proposed system gives good performance for the speed-sensorless induction motor control.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.551-557
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• 2006

The electrical frequency synchronized periodic torque ripple exits in the AC motor. There are various sources of torque ripple in AC motor such as current measurement error, dead time, etc. This paper proposes a compensation algorithm which suppresses undesired side effect known as the periodic torque ripple of AC motor. The torque ripple compensation classified as the speed ripple detector and torque ripple compensator. This paper proves a speed ripple minimization at steady state by analysis of torque ripple compensator. A new speed ripple detector improves the performance of torque ripple compensation algorithm. The simulation and experimental results show that the compensation algorithm is effective and the torque ripple compensation method improves the performance of speed ripple detector by eliminating torque ripples effectively.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1202-1209
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• 2004

This paper presents a design methodology of a Digital Servo Signal Processor for high speed CD-RW drive systems. The proposed Digital Servo Signal Processor enables us to develop CD-related systems for the very high speed applications and is one of the key components of the CD-RW systems. The proposed center compensation servo control is newly built for an actuator shaking due to the fast response of a step motor when it jumps to a long distance. A control method compensating for eccentricity of a disc is implemented for operating robustly at a higher rotational speed. This servo mechanism is more size efficient and less power consumed because it is implemented using a ARM7 embedded processor and hardware digital filters. Furthermore, it is convenient to upgrade firmware for the future required functions. From experimental results, we can see that the performance of the control system is improved greatly. The proposed servo algorithm shows a shorter setting time including a pull-in time and a faster access time. It can be applied easily to the DVD-ROM and the DVD-RAM which have the same optical structure.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.315-316
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• 2011

This paper presents speed control scheme of the PMSM which has torque compensator to reduce the speed error and ripple. The proposed speed controller is based on the conventional PI control scheme. But the additional torque compensator which is different to the conventional differential controller produces a compensation torque to suppress speed ripple. In order to determine the proper compensation, the activation function which has discrete value is used in the proposed control scheme. With the proposed activation function, the compensation torque acts to suppress the speed error increasing. The proposed speed control scheme is verified by the computer simulation and experiments of 400[W] PMSM. In the simulation and experiments, the proposed control scheme has better control performance compare than the conventional PI and PID control schemes.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.429-436
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• 2015

Torque ripples generate mechanical vibration at low speed and acoustic noise at high speed. The back emf harmonics of a PM synchronous motor is one of the main sources of torque ripples. To reduce torque ripples resulting from back emf harmonics, dq-axis harmonic currents that reduce the torque ripples are generally compensated to the current controller. Harmonic current compensation is effective at low speed, but it is not applicable at high speed because of the limited bandwidth of the current controller. In this study, dq-axis harmonic voltage compensation that can reduce torque ripples at high speed is proposed. The dq-axis harmonic voltages are calculated from the motor speed and the dq-axis harmonic currents. The effectiveness of the proposed method in reducing torque ripple is verified by a simulation and experiments.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.163-167
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• 2014

To prove the vibration and speed error problems caused by the nonlinear friction characteristics and load variation of the hydraulic system, a PID speed controller and a load compensation controller for the hydraulic inverter-fed elevator are proposed. The load compensation controller is composed by the PI controller and the speed controller is composed by the PID controller. The P,I and D gains of the control parameters are obtained by the frequency response of system transfer function. The Effectiveness of the proposed controller are shown by experimental results, which the proposed controller yields robustness with load variations and stable and good speed and acceleration responses with less oscillations.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.3
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• pp.253-259
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• 2004

This paper presents a speed controller method based on the disturbance torque observer for high-performance speed control of the brushless DC (RLDC) motor. In case of the speed control of robot arms and tracking applications with lower stiffness, we cannot design the speed controller gain to be very large from the viewpoint of the system stability Thus, the feedforward compensation method using disturbance torque observer was proposed. This method can improve the speed characteristic without increasing the speed controller gain. The speed characteristic against disturbance torque can be improved when the bandwidth of the speed controller cannot be made large enough. Consequently, the speed control of the BLDC motor for the high-performance application become achieved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.195-198
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• 2000

It can be acquired the high effective productivity through of high speed, precision of machine tools, and then, machine tools will be got a competitive power. Industrially advanced countries already developed that the high speed feed is 60m/min using the high speed ball screw. Also, a lot of problems have happened the feed drive system. It is necessary to study about the characteristics of thermal deformation played a more critical role than static stiffness and dynamic rigidity in controlling the level of machining accuracy. In spite of the improving the thermal deformation characteristics of machine tools at the design stage, there are always some residual errors that have to be compensated for during machining. In this study, thermal deformation error automated compensation device with multiple linear regression is proposed that thermal deformation error can be eliminated at the machining stage. The developed device has been practically applied to the feed drive unit.