Browsing by Author "Jeng, Shyr-Long"

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A Multicell Linear Power Amplifier for Driving Piezoelectric Loads
(2008-10-01)
Jeng, Shyr-Long
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Tung, Yung-Cheng
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機械工程學系
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Department of Mechanical Engineering
A multicell amplifier is developed by connecting floating signal modules in series to drive piezoelectric devices. The amplifier generates a high voltage gain by summing the individual module gains. The bandwidth equals that of a single module. The multicell amplifier provides a means of achieving high power and can divide the total power dissipation among the modules, because each module delivers the same output voltage and current. A prototype circuit that consists of six floating signal modules exhibits precise linear operation over a wide range of input frequencies and capacitive loads. The circuit provides a 200-V output swing with a corner frequency of around 100 kHz at a driving capacitive load of 0.1 mu F. The slew rate is as high as 115 V/mu s, and the maximum output current is +/- 2.6 A. The practicality and performance of the presented modular implementation concepts were verified by the close match between the simulated and experimental results.
A novel no-dead-time sinusoidal modulation method for three phase inverter
(2017-01-01)
Jeng, Shyr-Long
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Wu, Chih-Chiang
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機械工程學系
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Department of Mechanical Engineering
A lthough the dead time in pulse-width modulation (PWM) inverters prevents short circuiting of the dc source, it also causes serious problems such as waveform distortion and voltage decreases. In this paper, a novel modulation method that combines the concepts of a six-step square wave and space vector modulation (SVM) is proposed. Compared with the conventional SVM methods in which the dead time should be set to avoid short circuiting problems, the proposed novel no-dead-time modulation method not only increases the switching frequency potential by enabling one transistor at a time in each phase leg without considering dead time setting but also reduces the switching loss with only three transistors operating in every section in one cycle of rotation. The PWM duty ratio formula of the specified section for each power transistor is derived and verified using software for power electronics simulation (PSIM). The simulation model of this novel modulation method is constructed and tested by using a three-phase inductance-resistance load. The simulation results are presented to confirm the validity of the proposed modulation method.
Comparison of Parasitic Capacitances of Packaged Cascode Gallium Nitride Field-efect Transistors
(2018-01-01)
Wu, Chih-Chiang
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Jeng, Shyr-Long
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機械工程學系
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Department of Mechanical Engineering
In this work, we examined the electrical characteristics of laboratory-fabricated cascode gallium nitride field-effect transistors (GaN FETs) and analyzed their parasitic capacitances. The calculated results were in good agreement with the experimental results and showed that commercial GaN FETs have superior switching performance, whereas laboratory-fabricated GaN FETs require further improvement.
Design and Analysis of Spatial Parallel Manipulator for Dual Axis Solar Tracking
(2014-06-01)
Jeng, Shyr-Long
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Lue, Bin-Han
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This work develops a solar tracker that is configured in a parallel manipulator structure for maximum power generation. The conventional solar tracker with a serial gimbaled structure is simply supported by the central pivot in the module frame of the solar panel, and the structural deformation of the frame causes the PV cells on the side of the panel to be frequently out of focus. Accordingly, the power efficiency of the PV can fall rapidly for each degree of misalignment with respect to the sun. This work introduces a spatial parallel mechanism to increase the rigidity of the solar tracker structure and thereby improve its power efficiency. The prototype mechanism that is demonstrated in this work can feasibly track the sun completely from sunrise to sunset at latitude of 23.7 N degrees. Different tracking postures against the solar hour at the summer solstice, spring equinox, and winter solstice are animated.
Design and development of an IoT-based web application for an intelligent remote SCADA system
(2018-01-01)
Kao, Kuang-Chi
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Chieng, Wei-Hua
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Jeng, Shyr-Long
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機械工程學系
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Department of Mechanical Engineering
This paper presents a design of an intelligent remote electrical power supervisory control and data acquisition (SCADA) system based on the Internet of Things (IoT), with Internet Information Services (IIS) for setting up web servers, an ASP.NET model-view- controller (MVC) for establishing a remote electrical power monitoring and control system by using responsive web design (RWD), and a Microsoft SQL Server as the database. With the web browser connected to the Internet, the sensing data is sent to the client by using the TCP/IP protocol, which supports mobile devices with different screen sizes. The users can provide instructions immediately without being present to check the conditions, which considerably reduces labor and time costs. The developed system incorporates a remote measuring function by using a wireless sensor network and utilizes a visual interface to make the human-machine interface (HMI) more instinctive. Moreover, it contains an analog input/output and a basic digital input/output that can be applied to a motor driver and an inverter for integration with a remote SCADA system based on IoT, and thus achieve efficient power management.
Estimating Speed Using a Side-Looking Single-Radar Vehicle Detector
(2014-04-01)
Jeng, Shyr-Long
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Chieng, Wei-Hua
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Lu, Hsiang-Pin
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機械工程學系
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Department of Mechanical Engineering
This paper presents a side-looking single-beam microwave vehicle detector (VD) system for estimation of per-vehicle speed and length. The proposed VD system is equipped with a 2-D range Doppler frequency-modulated continuous-wave (FMCW) radar using a squint angle. The associated Fourier processor uses an inverse synthetic aperture radar (ISAR) algorithm to extract range and speed data for each vehicle using a single-beam FMCW radar. The simulation and experimental results show accurate estimations of vehicle speed and length. The measurement errors of speed and length were approximately +/- 4 km/h and +/- 1 m, respectively. The proposed method has excellent detection capability for small moving targets, such as bikes and pedestrians, at speeds down to 5 km/h. A commercial 10.6-GHz radar with signal processing modifications was used in the experiments.
Five-Axis Slerp for Tool-Orientation Planning in a Five-Axis CNC Machine
(2018-12-01)
Yan, Chang Dau
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Chieng, Wei-Hua
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Jeng, Shyr-Long
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機械工程學系
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Department of Mechanical Engineering
The quaternion spherical linear interpolation method (slerp), which many researchers have adopted for numerical control, is inadequate for tool-axisorientation planning in general five-axis computer numerical control machines. This paper explains why the quaternion slerp method fails to achieve constant rotational speed. The machining quality is degraded when the quaternion slerp method is used in five-axis machining. To compensate for this failure, this paper proposes a solution for tool-axis-orientation planning, the five-axis slerp method, which generates steady angular velocity of the interpolation curve.
Gallium Nitride Electrical Characteristics Extraction and Uniformity Sorting
(2015-01-01)
Jeng, Shyr-Long
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Wu, Chih-Chiang
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This study examined the output electrical characteristics-current-voltage (I-V) output, threshold voltage, and parasitic capacitance-of novel gallium nitride (GaN) power transistors. Experimental measurements revealed that both enhanced-and depletion-mode GaN field-effect transistors (FETs) containing different components of identical specifications yielded varied turn-off impedance; hence, the FET quality was inconsistent. Establishing standardized electrical measurements can provide necessary information for designers, and measuring transistor electrical characteristics establishes its equivalent-circuit model for circuit simulations. Moreover, high power output requires multiple parallel power transistors, and sorting the difference between similar electrical characteristics is critical in a power system. An isolated gate driver detection method is proposed for sorting the uniformity from the option of the turn-off characteristic. In addition, an equivalent-circuit model for GaN FETs is established on the basis of the measured electrical characteristics and verified experimentally.
HIGH-PERFORMANCE SINGLE-PHASE FULL-BRIDGE INVERTER USING GALLIUM NITRIDE FIELD EFFECT TRANSISTORS
(2017-01-01)
Wu, Chih-Chiang
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Jeng, Shyr-Long
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機械工程學系
;
Department of Mechanical Engineering
This paper presents the perfonnance of a single-phase full-bridge inverter based on wide-bandgap devices. The control strategy for the full-bridge inverter applies unipolar sinusoidal pulse width modulation. The experimental results demonstrated that a smaller figure of merit is preferred for a more efficient design; specifically, the full-bridge inverter using gallium nitride field effect transistors inside could easily reach 96% efficiency or more within a 100- to 1000-W range.
Least Squares Approach to Odometry based on Multiple Optical Mouse Sensors
(2010)
Wu, Ping-Lin
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Jeng, Shyr-Long
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This work describes an optical measuring device that comprises multiple laser mouse sensors to estimate 3-DOF planar motion. The linear least squares (LLS) method and nonlinear least squares (NLS) method are adopted to estimate the positions in this over-determined system. Two circular trajectories - non-orientated and self-orientated - are employed to evaluate the feasibility of the proposed device. The results are presented and validated by simulations and experimentally. For a circular trajectory with self-orientation, the estimated positions of device determined using the NLS method are associated with apparently smaller positional errors than those calculated using the LLS method. The noise at the sensor outputs has a large impact on the estimate of position. The analysis is essential to examining the error sources and increasing the accuracy of odometric measurement.
Motion behavior of triangular waveform excitation input in an operating impact drive mechanism
(2011-03-01)
Yang, Chia-Feng
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Jeng, Shyr-Long
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
Stable stepping motion from mechanical excitation of a piezoelectric device is generated using the impact drive mechanism (IDM) based on various triangular waveforms exerted by the counter mass speed. However, stick-slip behavior originating from the contact friction between the movable part and the guide surface poses an obstacle for precise modeling. Therefore, this work presents a concise impulse model for mechanism control of stepping motion behavior. The proposed impulse model incorporates the duty ratio and input frequency of the triangular waveform of counter mass relative displacement as the system input and outputs the estimated step size and the behavior of the stepping motion. An enhanced version of the dynamic model and our experimental results validate the efficacy of the proposed model. An adequate design and control of IDM motion is highly promising for use in nano-scale positioning. (C) 2010 Elsevier B.V. All rights reserved.
Multi-Level Balanced Isolated Floating Difference Amplifier
(2008-11-01)
Tung, Yung-Cheng
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Jeng, Shyr-Long
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
An innovative amplifier is proposed for applications involving high capacitive load and large voltage output swing, such as piezoelectric (PZT) actuator drivers. This amplifier is configured in a multi-level arrangement with floating amplifiers, yielding a high voltage gain as a sum of all individual gains from its operational amplifiers. The merits of such an amplifier also include a wide bandwidth and high potential power. Experiments using a six-level arrangement demonstrate a 100 kHz bandwidth with +/-200 V output swing for different capacitive loadings.
Outrigger Force Measure for Mobile Crane Safety Based on Linear Programming Optimization#
(2010)
Jeng, Shyr-Long
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Yang, Chia-Feng
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Chieng, Wei-Hua
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機械工程學系
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Department of Mechanical Engineering
This work presents a linear programming simplex method for evaluating allowable reaction forces of multiple outriggers with stability constraints. Minimum/maximum pruning approach is adopted to increase the computational efficiency of assessing the outrigger forces when a mobile crane is kept level by the supports of four outriggers. Determining the outrigger forces is an effective means of preventing a mobile crane from tipping over or outrigger failures. Two indices, i.e., moment-index and force-index, which quantify the tendency of tip-over behavior of mobile cranes and examine the bearing capacity of outrigger, are introduced to improve the safety measures. The safety hoist criteria of two mobile crane types equipped with different outriggers are analyzed to demonstrate the feasibility of the proposed scheme. An intelligent anti-upset device that utilizes the outrigger-based stability measures and selectively suppresses critical steering commands in real time is implemented to ensure safe crane operations.
Simulation Model Development for Packaged Cascode Gallium Nitride Field-Effect Transistors
(2017-08-01)
Wu, Chih-Chiang
;
Jeng, Shyr-Long
;
機械工程學系
;
Department of Mechanical Engineering
This paper presents a simple behavioral model with experimentally extracted parameters for packaged cascode gallium nitride (GaN) field-effect transistors (FETs). This study combined a level-1 metal-oxide-semiconductor field-effect transistor (MOSFET), a junction field-effect transistor (JFET), and a diode model to simulate a cascode GaN FET, in which a JFET was used to simulate a metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT). Using the JFET to simulate the MIS-HEMT not only ensures that the curve fits an S-shape transfer characteristic but also enables the pinch-off voltages extracted from the threshold voltage of the MIS-HEMT to be used as a watershed to distinguish where the drop in parasitic capacitance occurs. Parameter extraction was based on static and dynamic characteristics, which involved simulating the behavior of the created GaN FET model and comparing the extracted parameters with experimental measurements to demonstrate the accuracy of the simulation program with an integrated circuit emphasis (SPICE) model. Cascode capacitance was analyzed and verified through experimental measurements and SPICE simulations. The analysis revealed that the capacitance of low-voltage MOSFETs plays a critical role in increasing the overall capacitance of cascode GaN FETs. The turn-off resistance mechanism effectively described the leakage current, and a double-pulse tester was used to evaluate the switching performance of the fabricated cascode GaN FET. LTspice simulation software was adopted to compare the experimental switching results. Overall, the simulation results were strongly in agreement with the experimental results.
Switching performance of GaN FETs in terms of turn-off resistance characteristics: an experimental study
(2016-01-01)
Wu, Chih-Chiang
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Jeng, Shyr-Long
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機械工程學系
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Department of Mechanical Engineering
This study evaluated the AC parasitic capacitances and turn-off resistance of GaN FETs. Moreover, the study proposes an easily adjustable gate drive circuit appropriate for driving E-mode, cascode, and D-mode GaN FETs in the same driver topology. The proposed gate drive circuit involving only positive supply was established to provide not only a positive gate drive voltage to E-mode and cascode GaN FETs, but also a negative gate drive voltage to D-mode GaN FETs. This study also presents a simple circuit for shifting gate drive voltage levels to meet the driving voltage required for fully turning on or turning off GaN FETs. In cascode GaN FETs, the gate drive circuit incorporates additional resistor-capacitor-Zener diode (RCD) circuits applied to achieve a faster discharge rate, thereby increasing the switching speed by offering a negative turn-off voltage when the transistor is engaging in a turn-off process. In D-mode GaN FETs, the additional RCD circuits increase the drain current to enable the gate drive voltage to increase, resulting in the power transistor being turned on, thereby achieving a full conduction state to reduce on-state resistance. This paper presents comparisons of the switching performance of the different GaN FETs through the proposed gate drive circuit.