Browsing by Author "Chin, KP"

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Automatic flux-weakening control of permanent magnet synchronous motors using a reduced-order controller
(2000-09-01)
Chen, JJ
;
Chin, KP
;
機械工程學系
;
Department of Mechanical Engineering
This study presents a novel means of designing a simple and effective position and velocity controller for permanent magnet synchronous motors (PMSM). In contrast to the conventional two-loop control methods with full-state feedback, the proposed controller does not need current information of the motor for feedback purposes. However, under normal operation the steady-state d-axis current can still be controlled to zero to minimize power dissipation. In addition, implementing a simple overmodulation strategy allows the controller to automatically generate a flux-weakening control to expand the range of operating speed when voltage saturation occurs. In addition to not depending on system parameters used by the controller, the automatically generated demagnetizing current is also optimal in the sense of minimum power dissipation that differs from the maximum output torque design or the constant power design of the general flux-weakening control methods. Simulation and experimental results show that the controller can achieve an effective speed and position control with near-minimum power dissipation, even when voltage saturation occurs.
Minimum copper loss flux-weakening control of surface mounted permanent magnet synchronous motors
(2003-07-01)
Chen, JJ
;
Chin, KP
;
機械工程學系
;
Department of Mechanical Engineering
This study presents a novel current loop design method capable of automatic flux-weakening control with minimum copper loss for surface mounted permanent magnet synchronous motors (SPMSM). The proposed current controller can automatically re-compute the d-axis current command to defer output voltage saturation. Consequently, the motor operations in the flux-weakening region are also contained in the stable operating region. Analysis results indicate that since the output voltage vector in the flux-weakening region produced by this controller is consistently on the boundary of the maximum output voltage vector allowed by the inverter, the corresponding flux-weakening current is the optimal value in the sense of minimum copper loss. This minimum copper loss design differs from the maximum output torque design and the constant power design of the flux-weakening control methods found in the literature. Experimental results further demonstrate the feasibility of the proposed current controller and its ability to maximize the speed range of the motor drive for a given inverter capacity.
Shaft-sensorless control of permanent magnet synchronous motors using a sliding observer
(1996)
Chin, KP
;
Hong, ZH
;
Wang, HR
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機械工程學系
;
Department of Mechanical Engineering
In this paper, two nonlinear sliding observers are developed for speed-sensorless control of permanent magnet synchronous motors. One of the observer estimates the rotor position and velocity based on the current measurement. The other observer estimates the load torque in addition to the rotor position and velocity. Both theoretical analyses and experiments show that, using either observer for speed-sensorless control, the steady-state velocity error converges even when there is an external load torque applied to the rotor. However, when the external load is present, the position estimation error of the control system with torque estimation and compensation is much small than the system without torque estimation and compensation.
Stability of current-sensorless control of permanent magnet synchronous motors
(2001-03-01)
Chen, JJ
;
Chin, KP
;
機械工程學系
;
Department of Mechanical Engineering
This study applies Lyapunov's direct method to verify the stability of permanent magnet synchronous motors under singular perturbation control designs. The position and velocity controller designed herein does not require the current information of the motor for feedback purposes (current-sensorless), but the steady-state d-axis current can still be controlled to zero to minimize power dissipation. Combining Lyapunov's linearization stability analysis, the relation between overall closed-loop stability and control gains of this controller is also revealed. Experimental results demonstrate the effectiveness of this current-sensorless controller. In addition, the performance of this current-sensorless controller is compared with that of a full-state feedback controller. Clearly, the proposed current-sensorless controller can achieve zero positioning error within the resolution of an optical encoder. However, the same result is less easy to achieve using a full-state feedback controller due to the noise effect on the current measurements.
Stable shaft-sensorless control of permanent magnet synchronous motors using a sliding torque observer
(2003-06-01)
Horng, RH
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Chin, KP
;
機械工程學系
;
Department of Mechanical Engineering
Two nonlinear sliding observers are developed for speed-sensorless control of permanent magnet synchronous motors. One of the observers estimates the rotor position and velocity based on the measurement of the motor current, while the other estimates load torque as well as rotor position and velocity. The lower bounds of the sliding gain, which guarantee the existence of the sliding manifold, and the upper bounds, which guarantee the stability of the digital implementation of the sliding observers, are also presented. Both theoretical analyses and experimental results demonstrate that, regardless of the observer used for speed-sensorless control, the steady-state velocity error converges even when an external load torque is applied to the rotor. However, when an external load is present, the position estimation error of the control system with torque estimation and compensation is significantly smaller than that of the system without torque estimation and compensation.
Structure design of a 2-D high-aspect-ratio resonant microbearn accelerometer
(2005-07-01)
Hwang, DH
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Chin, KP
;
Lo, YC
;
Hsu, WS
;
機械工程學系
An accelerometer with concise structure having a resonant microbeam to measure 2-D acceleration is proposed. This structure is configured with a central proof mass suspended by four symmetrical and orthogonal high-aspect-ratio (HAR) microbeams. This dual-axis design is able to decouple a two-axis signal from a 2-D acceleration. An analytical model relating the linear relationship between the acceleration and the associated resonant frequency shift of microbeam is derived, and a finite element analysis (FEA) is also performed to confirm this model. The FEA result also shows that there is little cross talk between x and y directions of measurement, meaning that this structure is able to clecouple a planar 2-D acceleration into two independent acceleration components, and therefore the 1-D analytical model can be used to evaluate the 2-D acceleration on the x-y plane. In addition, the model is verified by testing results of one conventional dual-axis natural frequency shifted microaccelerometer (DFSM). The simulation result also shows that the sensitivity of the proposed HAR accelerometer is triple that of a conventional DFSM. (c) 2005 Society ofPhoto-Optical Instrumentation Engineers.
Ultrathick SU-8 mold formation and removal, and its application to the fabrication of LIGA-like micromotors with embedded roots
(2002-12-01)
Ho, CH
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Chin, KP
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Yang, CR
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Wu, HM
;
Chen, SL
In this study, a novel method to completely remove crosslinked SU-8 without remnants of the resist or destroying the electroplated microstructures was utilized. The LIGA-like fabrication of a side-driven electrostatic micromotor was employed as an example to describe polymerized SU-8 resist removal. Using near-UV light, nickel components of the micromotor were electroplated 160 Pm in a 300 mum-thick SU-8 mold. A comparison of various approaches based on a commercial remover was performed during the mold removal process. Experimental results showed that components having 1 mum-deep substructures embedded in the substrate could provide stronger structures to withstand the internal stress due to the photoresist deformation. In addition, when the height of the electroplated structure was below two-thirds of the photoresist mold thickness, the net clamping force on the resist could be effectively reduced to make the removal of SU-8 with heated remover successfully. The rotor and the stator with embedded roots were released cleanly and thereby, assembled to form a high-aspect-ratio micromotor. The technique of SU-8 removal and LIGA-like process presented herein can be applied to the fabrication of other high-powered microactuators. (C) 2002 Elsevier Science B.V. All rights reserved.