• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.5
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• pp.463-469
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• 2014

This paper proposes a maximum torque operation strategy for the direct torque control of a surface-mounted permanent-magnet synchronous motor (SPMSM). The proposed method analyzes the available operation region of the stator flux of the SPMSM under voltage and current constraints. Based on this analysis, the optimal stator flux trajectory that yields the maximum torque is obtained across the entire operation region, including constant torque and constant power regions. The proposed strategy is also applicable in the flux-weakening region II operation of the SPMSM, which has no speed limit. The validity of the proposed method is verified through experiments conducted on an 800 W SPMSM drive system.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1047-1050
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• 1993

Recently, AC servo motor has expanded its application areas the to the development of the power semi-conductor and control technology. But it has large torque ripple for its nonlinear characteristics and phase commutaion. In this paper, we proposed the switching angle overlapping method, and current control using tracking method in order to generate the constant torque of AC servo motor that has the trapezoidal back e.m.f. It is compared the these types of control method with the characteristics through simulation. We show that these methods lead the torque ripple to reduce and makes the position and speed characterlistics improved effectively. Also we prove that current control using tracking method is the best way to reduce torque ripple among the these types of control method.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.21-24
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• 2002

The vector control system of an induction motor is the high performance drive system to achieve the instantaneous torque control. The vector control system is greatly divided into the direct control, and the indirect control that the most widely is used, The indirect vector control needs the rotor time constant, which changes widely according to the temperature, frequency, and current amplitude. The incorrect time constant leads to the saturation of magnetic flux or under-excitation phenomena. As a result, that deteriorate the control performance. Therefore, in this paper, the effect of time constant variation is investigated and its on-line tuning algorithm is proposed. The time constant using the torque angles was calculated and that of the validity of algorithm proposed was proved through the computer simulation and the experiment.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.2
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• pp.109-116
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• 2001

The paper presents a speed control algorithm for a full pitch-controlled wind turbine system. Torque of a blade generated by wind energy is a nonlinear function of wind speed, angular velocity, and pitch angle of the blade. The design of the controller, in general, is performed by linearizing the torque in the vicinity of the operating point assuming the angular velocity of the blade is constant. For speed control, however the angular velocity is on longer a constant, so that linearization of the torque in terms of wind speed and pitch angle is impossible. In this study, a reference pitch model is derived in terms of a wind speed, angular velocity, and pitch angle, which makes it possible to design a controller without linearizing the nonlinear torque model of the blade. This paper also suggests a method of designing a hydraulic control system for changing the pitch angle of the blade.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.405-411
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• 2012

This paper deals with direct torque control of an induction motor (IM) with constant switching frequency. The desired torque is obtained from the speed controller which is designed using the IP controller. Decoupling control of torque and flux is developed based on the energy model of IM using the IP controller strategies. The desired d-axis and q-axis stator voltage components are obtained from the designed controller, which decouples torque and flux. The constant switching frequency can be applied using space-vector pulse width modulation, since the desired stator voltage can be known from the decoupling torque and flux controllers. In order to achieve stable operation of the proposed IP controllers, the gains of the controllers are chosen by setting the poles in negative (left) half of s-plane and by choosing the rising time for the response of the step function. The proposed controller was verified in simulations using Matlab/Simulink and results have proven excellent performance. It was found that the proposed IP controllers can provide excellent performance to track the desired torque and speed and to reject the disturbance of load.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.1
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• pp.9-15
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• 2006

The conventional hysterysis band DTC(Direct Torque Control) strategy have relatively high torque ripple at low speed and variable switching frequency according to motor speed even though it provides a fast torque response with very simple scheme consisted with only two hysteresis band comparators and a switching table for torque and flux control. In this paper, author proposed a new DTC scheme based on the torque slope and reference voltage control. The new scheme can maintain the minimized torque ripple and constant switching frequency. Experimental tests carried out with an 1.5kW induction motor drive system show improved dynamic characteristics and prove the feasibility of proposed strategy.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.36-36
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• 2000

The paper presents a speed control algorithm for a full pitch-controlled wind turbine system. Torque of a blade generated by wind energy is non-linear function of a wind speed, angular velocity, and pitch angle of the blade. The design of a cor_troller, in general, is performed by linearizing the torque in the vicinity of a operating point assuming the angular velocity of the blade is constant. For speed control, however, the angular velocity is no longer a constant, so that linearization of the torque in terms of a wind speed and pitch angle is impossible. In this study, a reference pitch model is derived in terms of a wind speed, angular velocity, and pitch angle, which makes it possible to design a controller without linearizing the non-linear torque model of the blade. The validity of the algorithm is demonstrated with the results produced through sets of experiments.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.1
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• pp.1-8
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• 2003

The paper proposes instantaneous torque control of IPMSM for maximum torque drive of torque and current plane. The control scheme is based on the mathematical model of the motor and is applicable to the constant torque and field weakening operations. The scheme allows the motor to be driven with maximum torque per ampere(MTPA) characteristic below base speed and it maintains the maximum voltage limit of the motor wide field weakening and the motor current limit under all conditions of operation accurately. For each control mode, a condition that determines the optimal d-axis current $^id$ for maximum torque operation is derived. The proposed control algorithm is applied to IPMSM drive system for drive of wide speed range, the operating characteristics controlled that maximum torque control are examined in detail by simulation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.2
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• pp.59-64
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• 2004

Study of an accurate and robust braking control method is required as a technical improvement to the servo system. In particular, the braker exhibiting constant braking performance under speed variation conditions of the prime mover needs to be investigated. In this paper, the braking torque of the eddy current braker between the electromagnet stator and rotating disk is analyzed. The torque-speed characteristics and accurate disk construction are represented. From the computer simulation results, it was found that eddy current braking torque is linear or approximately constant over the desired speed range depending on the rotor material, disk construction, pole number and pole displacement of the stator. These relations are confirmed by experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1751-1756
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• 2007

This paper presents a high performance pressure control scheme for SR(Switched Reluctance) type hydraulic oil pump using DITC(Direct Instantaneous Torque Control). SR drive has a good feature for pump applications due to a high efficiency, high speed and high torque characteristics. But, SR drive has high torque ripple in commutation region. So, the pump pressure variation is high in the region. In order to reduce the pressure variation, DITC combined with pressure control scheme is presented in this paper. A simple PI controller with flow and pressure limit, generates a reference torque to keep the constant actual pump pressure. The direct torque controller of SR drive generates inverter switching signals according to a control rule and a torque estimator. Computer simulation and experiemtal results show the validation of the proposed control scheme.