Brushless synchronous generators (BSG) are typically used to produce an island network whose voltage is close to the nominal voltage of the generator. Generators are often used also in test-field applications where al...
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ISBN:
(纸本)9781665435543
Brushless synchronous generators (BSG) are typically used to produce an island network whose voltage is close to the nominal voltage of the generator. Generators are often used also in test-field applications where also zero output voltage is needed. The exciter construction and magnetic remanence may lead to a situation where the non-loaded generator terminal voltage cannot be controlled close to zero but a significant voltage is always generated because the exciter remanence. A new brushless synchronous generator excitation and de-excitation converter topology for test applications is proposed. The purpose is to achieve full voltage control from zero to nominal level without modifications to the generator. Insulated-gate bipolar transistor (IGBT) and Field-Programmable Gate Array (FPGA) technology are used to achieve the required fast and accurate control. In the work, simulation models were first derived to characterize the control performance. The proposed converter topology was then verified with the simulation model and tested empirically with a 400 kVA brushless synchronous generator. The results indicate that the exciter remanence and self-excitation can be controlled through the exciter stationary field winding when the proposed converter topology controls the field winding current. Consequently, in highly dynamical situations, the system is unaffected by mechanical stresses and wear in the generator.
A double input DC-DC converter based on Zero-Voltage Transition technique enough to attract power from two distinct sources serving a joint dc-bus is projected. This converter belongs to higher-order family behaving a...
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ISBN:
(纸本)9781509007745
A double input DC-DC converter based on Zero-Voltage Transition technique enough to attract power from two distinct sources serving a joint dc-bus is projected. This converter belongs to higher-order family behaving as buck converter with one dc source and it also performs as both buck and boost converter with another source. Here the two sources either independently or concurrently deliver power to the consequent load with least ripple current is an important aspect of the suggested converter. This aspect is mainly needed for photo-voltaic applications. The main objective here is to realize the soft-transition by incorporating the ZVT cell into the double input DC-DC converter which allows to increase the efficiency by decreasing the switching losses and current/voltage stresses in the converter. The digital voltage controller for the converter is designed using SISO tool in MATLAB. Analysis of 24V, 96W converter is done through both experimental process and simulation.
Compressor aerodynamic instabilities can have adverse effects on compression system performance. In this paper we develop a multi-mode model for rotating stall and surge in axial flow compression systems that lends it...
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Compressor aerodynamic instabilities can have adverse effects on compression system performance. In this paper we develop a multi-mode model for rotating stall and surge in axial flow compression systems that lends itself to the application of nonlinear control design. Using Lyapunov stability theory, a novel nonlinear globally stabilizing control law based on equilibria-dependent Lyapunov functions with converging domains of attraction is developed. The multi-mode model is used to show that the second and higher-order disturbance velocity potential harmonics in the flow equations strongly interact with the first harmonic during stall inception and must be accounted for in the control-system design processes.
The inverse system approximation using the finite impulse responses (FIR) and the corresponding model-order determination are essential to a broad area of signal processing applications such as seismic data processing...
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ISBN:
(纸本)9781424419968
The inverse system approximation using the finite impulse responses (FIR) and the corresponding model-order determination are essential to a broad area of signal processing applications such as seismic data processing, communication equalization, acoustic echo cancelation, plant control, etc. To the best of our knowledge, there exists no explicit formulation of the exact mean-square approximation error for the truncated inverse filters. Therefore, in this paper, we derive the exact L-2 approximation error function with respect to the model orders for the truncated inverse filter using an FIR. Our newly derived L-2 approximation error evaluation can be employed for the communication or signal processing system design involving the inverse filtering in the future.
Space commercialization increasingly requires servicing, construction, and maintenance of space structures and satellites in orbit. In this paper, a minimum-time optimal control law for a flexible spacecraft during an...
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It is evident that effective control over chaos in the forward converter is very important for engineering applications. In this paper, a mathematical model of the forward converter is firstly derived. Secondly, the n...
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ISBN:
(纸本)1424435064
It is evident that effective control over chaos in the forward converter is very important for engineering applications. In this paper, a mathematical model of the forward converter is firstly derived. Secondly, the nonlinear phenomenon in the forward converter is discussed, and then we apply the method of time-delay feedback control over chaos in the forward converter. The validity of this method is confirmed by simulation results.
To enhance the overall efficiency of a dual-bridge resonant converter, a new asymmetric pulsewidth modulation (PWM) control named extended pulsewidth modulation (EPWM) with both variable pulsewidth and variable symmet...
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To enhance the overall efficiency of a dual-bridge resonant converter, a new asymmetric pulsewidth modulation (PWM) control named extended pulsewidth modulation (EPWM) with both variable pulsewidth and variable symmetry is introduced in this article, which is applied to the high-voltage-side bridge of the converter and is combined with phase-shift control to form a 3-D gating scheme. A specified control strategy based on the 3-D gating scheme is then derived for the purpose of minimum tank current operation. Thanks to the flexibility brought by EPWM, full zero-voltage switching (ZVS) operation range is maintained as large as that of a conventional PWM-based minimum current trajectory, and only one switch loses ZVS at light load. The modulated voltage pulsewidth is kept at high level in a wide load range, which compromises the by-effect of high-order harmonics due to asymmetric modulation. Besides, the backflow power on both sides is almost minimized naturally. Therefore, the proposed control trajectory can have better performance in a light-load region than previous reported solutions. Experimental results prove the accuracy and effectiveness of the proposed minimum current operation with wide ZVS range and show the improvement of overall conversion efficiency.
A jointly probabilistic approach to formulate the performance analyses of the outage probability and the average bit-error-rate (BER) is presented with the max-min relay selection scenario. The relay hop is modeled as...
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ISBN:
(纸本)9781479980888
A jointly probabilistic approach to formulate the performance analyses of the outage probability and the average bit-error-rate (BER) is presented with the max-min relay selection scenario. The relay hop is modeled as a closed-form probability density function (PDF) of the composite Rayleigh plus log-normal fading variables with a conditioned relay power constraint. Numerical analyses with dual-hop multi-relay link demonstrate that our probabilistic approach has promised accuracy, in comparison with the exact solution (integral form), leading to an effective analysis framework for more generalized fading environments, including out-door composite fading and marco-cell relaying system applications. Thus, this probabilistic approach effectively simplifies the performance analysis in terms of the shadowing effect and diversity order over cooperative multi-relay links.
Since the applications of mobile WiFi and Bluetooth signals are very popular and mature, in this paper, we propose an intelligent parking management system based on the technologies of WiFi positioning and Bluetooth c...
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ISBN:
(纸本)9781728173993
Since the applications of mobile WiFi and Bluetooth signals are very popular and mature, in this paper, we propose an intelligent parking management system based on the technologies of WiFi positioning and Bluetooth control to manage the vehicles entering or exiting the parking lot. Only a dedicated app for the parking lot needs to be installed on the user's mobile phone, when the user drives near the parking lot, the roadside unit (RSU) end of parking lot can automatically complete the operation of vehicle identification. Based on the convenience and practicability, therefore, such a parking system using WiFi positioning and Bluetooth control is worth popularizing.
With the advanced development and maturing of small satellite technologies, there is a high commercial demand for low-cost small satellites with fast delivery for a multitude of applications. This paper presents a har...
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ISBN:
(纸本)9781665490320
With the advanced development and maturing of small satellite technologies, there is a high commercial demand for low-cost small satellites with fast delivery for a multitude of applications. This paper presents a hardware-in-the-loop system for testing the satellite's attitude determination and control system and the Agile framework from software engineering practices to guide resource-effective end-to-end development processes, while maintaining a comprehensive system validation. Experimental results for design verification of satellite's Attitude Determination and control Systems (ADCS) using our ongoing concurrent multiple satellite programs are presented.
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