Browsing by Author "Fang, CH"

Now showing 1 - 9 of 9

A dynamic model of mutual inductance for the compensation of current control utilizing the optimum searching strategy for switched reluctance motor drives
(2004)
Huang, WN
;
Teng, CC
;
Fang, CH
;
Chen, CH
;
電控工程研究所
A methodology to design the dynamic model taking the mutual inductance into account for the switched reluctance motor (SRM) drives is proposed in this paper. The overall consideration is focus on the current control compensation strategy that related to the practically existing unmodeled parameter, the mutual inductance, to improve the drives performance. A mutual inductance related expression is discussed and then an optimum searching method, chosen for ease-of-applying, is utilized for solving the key parameter owning on-line computational procedures potentials. By the presented model based on the motor characteristics analytical opinion, the relationship between the compensation current command and the neglected effect of the drives output can be established. The effectiveness of this model is demonstrated by the comparison with/without the dynamic model being involved.
A flux estimation method for a permanent-magnet synchronous motor
(2004-11-01)
Wang, SH
;
Fang, CH
;
Lin, SK
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper deals with the flux estimation of a permanent-magnet synchronous motor (PMSM). Contrary to the conventional no-load test, the proposed method needs no extra servomotor. It is simply to drive the PMSM in a single-phase mode with the currents large enough to make the PMSM rotate in the same direction. Under such a condition, the flux of the PMSM can be easily estimated. (C) 2004 Elsevier B.V. All rights reserved.
Adaptive backstepping motion control of induction motor drives
(2004-05-01)
Lin, SK
;
Fang, CH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, an adaptive backstepping controller is proposed for position tracking of a mechanical system driven by an induction motor. The mechanical system is a single link fixed on the shaft of the induction motor such as a single-link robot. The backstepping methodology provides a simpler design procedure for an adaptive control scheme and provides a method to define the sliding surface if the robust sliding-mode control is applied. Thus, the backstepping control can be easily extended to work as an adaptive sliding-mode controller. The presented position control system is shown to be stable and robust to parameter variations and external disturbances. The effectiveness of the proposed controllers is demonstrated in experiments.
Adaptive sliding-mode torque control of a PM synchronous motor
(2002-05-01)
Fang, CH
;
Huang, CM
;
Lin, SK
;
電控工程研究所
;
Institute of Electrical and Control Engineering
An adaptive sliding-mode torque control system, which incorporates the merits of both the sliding-mode control and the adaptive algorithm, is proposed. The sliding-mode controller is constructed by two integral surface functions. The uncertainty is formulated as a random variable around a constant mean, so that an adaptive mechanism is used to estimate the constant mean and the bound of the random variable. Moreover, an application of the proposed torque control to the position control of a motor is also presented. Some experiments verify the control theory and demonstrate the usefulness of the proposed control scheme.
Analysis on the depth of focus in flying optics
(1998-05-01)
Fang, CH
;
Lu, MH
;
光電工程學系
;
Department of Photonics
Based on a simplified model of Gaussian beam focusing, in which nontruncating, thin-lens, aberration-free, and on-axis optical systems are assumed and the thermal-lensing effect is neglected, a general and concise expression is derived to describe the variation of 1/e(2) radius of the focused beam as a function of input beam waist to lens spacing, lens-to-target plane spacing, input beam Rayleigh range, and focal length of lens. From this expression, we get the depth of focus (DOF) of flying optics with a fixed flying range, which is used as a merit function to determine the optimal solutions for system parameters. The results are very useful in the design and analysis of flying optics in laser material processing. Finally, a practical example describing the optimization of the output coupler for CO2 laser resonator is given. (C) 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)02505-7].
On-line parameter estimator of an induction motor at standstill
(2005-05-01)
Fang, CH
;
Lin, SK
;
Wang, SJ
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper describes an automatic identification procedure for an induction motor. The transfer function of the motor at standstill is used to obtain a linear parametric model. An on-line parameter estimator is then derived from this model. In the implementation of the proposed estimator, a PI current controller is constructed to stabilize the current signal and to prevent the flux from saturation. An experiment with an input that is persistently exciting verifies the theory of the proposed estimator and demonstrates its usefulness in industry applications. (C) 2004 Elsevier Ltd. All rights reserved.
Sensorless scalar-controlled induction motor drives with modified flux observer
(2003-06-01)
Wang, CC
;
Fang, CH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a simple sensorless scalar control algorithm to control the speed of an induction motor. First, a modified flux observer was employed to estimate the stator flux with the voltage command and the feedback current. Then, based on the mathematical model of the induction motor, the slip frequency was calculated, and the frequency of the voltage command was compensated. An auto-boost controller was designed to overcome the decrease in voltages of the stator resistance and to maintain constant stator flux amplitude. To improve the pure integration problem, a highpass filter was installed in the stator flux observer. In this filter, the cut-off frequency is proportional to the voltage frequency; therefore, the phase shift and amplitude degradation of the estimated flux can be corrected easily. Finally, to demonstrate the proposed control algorithm, a PC-based experimental system was constructed in a 1-hp induction motor. Experimental results are presented to validate the effectiveness of our design.
Sliding-mode direct torque control of an induction motor
(2001)
Lin, SK
;
Fang, CH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes new sliding-mode direct torque control (DTC) for an induction motor. This DTC is established by designing two sliding surfaces for the torque and the flux. We propose a novel sliding surface for the torque, which is based on the integral-sliding surface, whereas the sliding surface for the flux follows that of Benchaib et al. [16]. We also modify the flux observer of Benchaib and Edwards [17] by the adaptive sliding-mode method. This not only eliminates the estimation of the uncertainty bounds, but also improves the performance of sliding control. A practical application of the proposed DTC to the position control of a motor is also presented. Some experiments verify the control theory and demonstrate the usefulness of the proposed DTC.
Sliding-mode linearization torque control of an induction motor
(2004-09-01)
Lin, SK
;
Fang, CH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes a sliding-mode linearization torque control (SMLTC) for an induction motor (IM). An ideal feedback linearization torque control method is firstly adopted in order to decouple the torque and flux amplitude of the IM. However, the system parameters are uncertainties, which,will influence the control performance of the IM in practical applications. Hence, to increase the robustness of the IM drive for high- performance applications, this SMLTC aims to improve the immunity of those uncertainties. We modify the flux observer of Benchaib and Edwards [15] by means of the adaptive sliding-mode method. This not only eliminates the estimation of the uncertainty bounds, but also improves the performance of sliding control. In addition, a practical application of the proposed SMLTC, with a model reference adaptive control (MRAC) scheme incorporated as the inner and outer loop controller used for position control, is also presented. Some experiments are presented to verify the control theory and demonstrate the robustness and effectiveness of the proposed SMLTC.