• Journal of Power Electronics
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• v.17 no.1
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• pp.161-171
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• 2017

To enhance the reliability of two-motor drive systems, this paper proposes an improved direct torque control (DTC) scheme (P-DTC) for five-leg dual-PMSM drive systems. First, the topology of a five-leg dual-PMSM drive system is illustrated. To clarify the analysis of the P-DTC, the standard DTC scheme for three-phase drive systems is presented. The operation of a five-leg dual-PMSM drive system is classified into three situations according to the definitions of the switching-vector unions. Compared with the existing DTC scheme (R-DTC), the P-DTC can minimize the replacement of active switching-vectors to zero switching-vectors. When this replacement cannot be avoided, the P-DTC uses a proposed master-slave selection principle to minimize the system error. Comparing with the R-DTC, the P-DTC has lower torque ripples, a wider speed range and a faster torque increasing response. Experiments have been carried out in the coupling and independent modes, and the effectiveness of the P-DTC is verified by the obtained results.

• Journal of Power Electronics
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• v.5 no.1
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• pp.36-44
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• 2005

This paper presents an implementation of high performance control of a reluctance synchronous motor (RSM) using a neural network with a direct torque control. The equivalent circuit in a RSM, which considers iron losses, is theoretically analyzed. Also, the optimal current ratio between torque current and exiting current is analytically derived. In the case of a RSM, unlike an induction motor, torque dynamics can only be maintained by controlling the flux level because torque is directly proportional to the stator current. The neural network is used to efficiently drive the RSM. The TMS320C3l is employed as a control driver to implement complex control algorithms. The experimental results are presented to validate the applicability of the proposed method. The developed control system shows high efficiency and good dynamic response features for a 1.0 [kW] RSM having a 2.57 ratio of d/q.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.1
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• pp.20-29
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• 2005

This paper presents an implementation of efficiency optimization of reluctance synchronous motor (RSM) using a neural network (NN) with a direct torque control (DTC). The equipment circuit considered with iron losses in RSM is analyzed theoretically, and the optimal current ratio between torque current and exiting current component are derived analytically. For the RSM driver, torque dynamic can be maintained with DTC using TMS320F2812 DSP Controller even with controlling the flux level because a torque is directly proportional to the stator current unlike induction motor. In order to drive RSM at maximum efficiency and good dynamics response, the Backpropagation Neural Network is adapted. The experimental results are presented to validate the applicability of the proposed method. The developed control system show high efficiency and good dynamic response features with 1.0 [kW] RSM having 2.57 inductance ratio of d/q.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.162-169
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• 2000

A Direct Drive Valve(DDV) hydraulic actuation system which is commonly used as an aircraft's control surface driving actuator has multi-loop control structure to ensure its safety operation. However, because of not perfect matching of one self channel characteristics with the others, the servo valve driving current of each channel can be widely different. Therefore, the long-time use of DDV actuator without any correction of these channel current offsets will cause the problem of performance or life expectancy degradation due to unwanted heats in the linear motor. A current equalization loop structure which can minimizes current offsets between channels is introduced and designed. The performance of the current equalization loop is investigated and verified through the analytic and experimental ways.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.123-129
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• 1996

Computed torque method has been used for precise trajectory control of the robotic system that involves nonlinear dynamics. It is hard to know exact values of robot system parameters, and the robot arm receives umpredictable interference from the working environment. These disturbances, especially in a direct drive robot, are directly transmitted to actuating motor without reduction. Modelling error and distrubance can cause significant errors in a trajectory tracking problem. In this paper, we propose a new controller that $H_{\infty}$controller is conbined to robot system linearized by computed torque. Simula- tions are made for comparing the performance of the proposed controller with that of a nonlinear $H_{\infty}$ controller proposed by Chen and also computed torque method.hod.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1052-1057
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• 1993

A scara type Direct Drive Arm(DDA) with two degrees-of-freedom is designed and implemented. The direct drive motor is used to furnish large torque to reduce the modeling error by the gear and chains. To control the DDA, a multiprocessor control structure with multirate dynamic control algorithm is designed. In the control algorithm, the dynamics of system is used to calculate the nominal control torque and the feedback controls are calculated with a parallel processing algorithm for each joint. The laboratory experiments on Hong-Ik DDA by dynamic control algorithm are presented and compared to that of PID control algorithm. This result shows that the proposed controller guarantees small trajectory error and stability. With this research, Hong-Ik DDA is expected to be utilized as A basic tool for robotics and control engineering.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.507-514
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• 2001

Direct drive servovalve(DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical Bode method.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.136-136
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• 2000

The direct drive servo valve(DDV) is composed of a DC rotor, link, valve spool and displacement sensor(LVDT) where the spool is directly coupled to the DC motor through the link. Since the DDV is a kind of one-stage valve, the robust controller is required to overcome the flow force effect on the spool motion. The mathematical equations are derived and the stability, accuracy and response speed of a DDV are investigated analytically using a linearized system block diagram. Proportional control, PID control. Time-Delay control, Sliding Mode control, and Proportional control using the load pressure are applied to DDV to find which one shows the best control performance. The digital computer simulation results show that the proportional control using the load pressure satisfies the design requirement of response speed and steady state error regardless of the variation of load pressure,

• Journal of Industrial Technology
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• v.18
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• pp.329-334
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• 1998

The purpose of this study is to design and manufacture a vibration exciter, which can be used in the education and research for the vibration engineering. For this purpose, a direct drive type vibration exciter is developed, which consists of a motor, an inverter, eccentric rotating sleeves and two excitation plates. Developed exciter is tested on some dynamic characteristics to evaluate its excitation performance. Test results show that the developed machine can excite bodies on the horisontal vibrating plates in x,y direction by the constant displacement amplitude in the frequency range below 50Hz, which confirm that the exciter can be used as a vibration testing machine in the low frequency range.