• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.183-192
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• 1998

In this paper, we measure the back-EMF and the thrust of a linear brushless DC motor along the relative position between coils and magnets in various speed environments in order to obtain the back-EMF and the thrust as a function of a motor position. The measured back-EMF function and thrust function of the position differ from the analytical ones within 5%. The measured back-EMF and thrust function can, then, be employed in controlling the thrust ripple of the linear motor. Furthermore, to minimize the torque ripple of the linear motor, we suggest the design method to shape the back-EMF and thrust function of the linear motor.

• International Journal of Control, Automation, and Systems
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• v.1 no.3
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• pp.351-357
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• 2003

A method of design optimization for minimization of force ripple and maximization of thrust force in a linear brushless permanent magnet motor without finite element analysis is represented. The design optimization method calculated the driving force in the function of electric and geometric parameters of a linear brushless PM motor using the sequential quadratic programming method. Using electric and geometric parameters obtained by this method, the normalized force ripple is reduced 7.7% (9.7% to 2.0%) and the thrust force is increased 12.88N (111.55N to 124.43N) compared to those not using design optimization.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.73-80
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• 1998

Recently, we have developed a linear brushless DC motor(LBLDCM) with high speed and precise position control performance to apply it to the semiconductor assembly and inspection machinery. It is composed of double side alignment by two armature-stator pairs and each pair is consist of a moving armature with 8 poles by 3 phase coils and a stator with rare earth permanent magnet (Nd-Fe-B) arrays. Through the thrust force analysis on a simplified and whole model of the suggested LBLDCM by an Electromagnetic FEM solver, skew angle of magnet arrays to reduce the thrust force ripple and the winding conditions of the armature is designed. From experimental results, the user's requirements was satisfied and we confirmed distinctly that the repeatable accuracy less than a micron of the linear motion can be obtained at high speed by the developed LBLDCM. This is owing to directly drive the work without the gear train.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.862-867
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• 1999

In general, the realization of high performance brushless permanent magnet motors which are widely used in servo drive is focused on the linear control for ripple-free torque. This is also the main problem that should be solved in all AC motors including induction motor to achieve high performance control, and recent papers deal with this problem. In this paper, the novel optimal excitation scheme of brushless permanent magnet motor producing loss-minimized ripple-free torque based on the d-q-0 reference frame is presented including 3 phase unbalanced condition. The optimized phase current waveforms that are obtained by the proposed method can be a reference values and the motor winding currents are forced to track it by delta modulation technique. As a results, it can be shown that the proposed work can minimize the torque ripple by the optimal excitation current for brushless permanent magnet motor with any arbitrary phase back EMF waveform. Simulation and experimental results prove the validity and practical applications of the proposed control scheme.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.143-146
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• 2001

Servomotors, especially linear brushless servomotors have numerous advantages over ball screws, timing belts, rack/pinion drives and friction drives compared wi th rotary servomotors This paper proposes an linear regression method as the estimated ion of unknown parameters from the linear brushless DC motor The estimated parameters are used to tune the gain of controller. In order to agree with this purpose, Digital Signal Processor (TMS320F240), developed for implementation of the motor control, is adopted in this study. The processor playing an important role in controller has A/D converters, PWM generators, riched I/O ports internally.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.866-872
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• 2014

The purpose of this paper was to find an effective method for measuring electromagnetic torque produced by a brushless DC motor with single-phase current sensing in real-time. A torque equation is derived from the theory of brushless DC motor. This equation is then validated experimentally with a motor dynamometer. A computer algorithm is also proposed to implement the electromagnetic torque estimation equation in real-time. Electromagnetic torque is a linear function of phase current. Estimating the electromagnetic torque in real-time using single-phase current is not appropriate with existing equations, however, because of the rectangular alternating-pulse nature of the excitation current. With some mathematical manipulation to the existing equations, the equation derived in this paper overcame this limitation. The equation developed is simple and so it is computationally efficient, and it takes only motor torque constant and single-phase current to evaluate the electromagnetic torque; no other parameters such as winding resistances, inductances are needed. The equation derived is limited to the three-phase brushless DC motor. It can, however, easily be extended to the multiphase brushless DC motor with the technique described in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.603-609
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• 2008

Slotless linear brushless DC motor are widely used in precision machine applications because of their advantages such as low of detent force, negligible iron loss. But they have a disadvantage such as low thrust density, thrust ripple, and excessive use of permanent magnet materials. These lead to undesirable performance and high production cost. In this paper, we deal with the design and characteristics investigation of a air-core tubular linear brushless DC(TLBLDC) motor with air-core stator and permanent magnet mover. And to investigate the static and dynamic characteristics of air-core TLBLDC motor, the prototype machine is manufactured and analyzed by F.E.M. and Matlab simulink simulations. Especially, dynamic characteristics of air-core TLBLDC motor driven with 6 step inverter are simulated by F.E.M.coupling with external circuit and Matlab simulink program, and measured for the prototype motor. The simulation results are compared to the experimental results such as current waves, thrust and speed curve.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.155-160
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• 2002

In this paper, a controller design for brushless linear motor is implemented. The designed controller is mainly composed of current, speed and position controller, which are carried out by the high-speed digital signal processor (DSP). In addition the PWM inverter is controlled by space voltage PWM method. This system is implemented by using 32-bit DSP (TMS320C31), a high-integrated logic device (EPM7192), and IPM (Intelligent Power Module) for compact and powerful system design. The experimental results show the effective performance of controller for the brushless linear motor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.969-972
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• 2000

In this paper, a controller design for brushless linear motor is proposed. The designed controller is mainly composed of speed and current controller, which are carried out by the high-speed digital signal processor(DSP). In addition the PWM inverter is controlled by space voltage PWM method. This system is implemented using by 32-bit DSP(TMS320C31), a high-integrated logic device(EPM7128), and IPM(Intelligent Power Module) for compact and powerful system design. The experimental results show the effective performance of controller for the brushless linear motor.

• International Journal of Control, Automation, and Systems
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• v.2 no.3
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• pp.279-288
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• 2004

This paper presents a novel design for a tubular linear brushless permanent-magnet motor. In this design, the magnets in the moving part are oriented in an NS-NS―SN-SN fashion which leads to higher magnetic force near the like-pole region. An analytical methodology to calculate the motor force and to size the actuator was developed. The linear motor is operated in conjunction with a position sensor, three power amplifiers, and a controller to form a complete solution for controlled precision actuation. Real-time digital controllers enhanced the dynamic performance of the motor, and gain scheduling reduced the effects of a nonlinear dead band. In its current state, the motor has a rise time of 30 ms, a settling time of 60 ms, and 25% overshoot to a 5-mm step command. The motor has a maximum speed of 1.5 m/s and acceleration up to 10 g. It has a 10-cm travel range and 26-N maximum pull-out force. The compact size of the motor suggests it could be used in robotic applications requiring moderate force and precision, such as robotic-gripper positioning or actuation. The moving part of the motor can extend significantly beyond its fixed support base. This reaching ability makes it useful in applications requiring a small, direct-drive actuator, which is required to extend into a spatially constrained environment.