1,720,982 research outputs found
Steady-State Simulation of LCI-Fed Synchronous Motor Drives Through a Computationally Efficient Algebraic Method
Full text linkWound-field synchronous motors (WFSMs) fed by load-commutated inverters (LCIs) are widely used for high-power applications in many fields like ship propulsion, oil and gas industry, and pumped-storage hydropower generation. Several design architectures exist for LCI drives, depending on the number of LCIs and their dc-link connection as well as on the number of WFSM phase count. The prediction of LCI drive performance at steady state is important in the design stage, especially in regard to the prediction of the torque pulsations, which can give rise to serious mechanical resonance issues. This paper proposes an algebraic method to simulate the steady-state behavior of LCI drives in all their configurations of practical interest. Compared to conventional dynamic simulation approaches based on differential equation solution, the method is much more computationally efficient and requires a very limited knowledge of system parameters. Its accuracy is experimentally assessed by comparison against measurements taken on a real LCI drive arranged according to various possible schemes. Furthermore, the advantages of the proposed algebraic method over the dynamic simulations are highlighted by comparison against the simulation results on a high-power LCI-fed WFSM drive in MATLAB/Simulink environment
Single-phase power line conditioning with unity power factor under distorted utility voltage
Full text linkThe paper proposes a control method of a single-phase active power line conditioner (APLC) aimed at correcting the power factor of linear and non-linear loads supplied by distorted voltage utility. The method, that is based on the single-phase p-q theory and utilizes a third-order sinusoidal signal integrator, gets utility unity power factor and, at the same time, overcomes the shortcomings of the solutions pursuing utility sinusoidal current, namely the possible onset of un-damped resonance phenomena and the reduction in the energy delivery capabilities; moreover, the method makes the power factor correction robust against the supply distortion. The excellent performance of the method is substantiated by testing it by means of a hardware-in-the-loop setup
Sizing Procedure of Reactive Electric Spring
Full text linkReactive electric spring (RES) is a technique aimed at stabilizing the user voltage in presence of grid voltage variations by means of a user-encapsulated circuit. In spite of the numerous papers on the matter, no expressions are still available to size the RES elements. This paper fills this lack, by drawing up a sizing procedure of them. The procedure starts with a targeted investigation of the RES operation and exploits the outcomes to provide expressions for the values of the passive elements as well as for the voltage-current ratings of the voltage source inverter (VSI). The sizing expressions are formulated in normalized form to emphasize their dependence on the parameters of the user non-critical load. Focus of the sizing procedure is on the two RES key-elements, namely the AC-side capacitor and VSI but the AC filter inductor and the DC-side capacitor are also sized. Two options for sizing the AC-side capacitors are also discussed. At last, the study case of a user supplied by a low-voltage distribution line is considered and the sizing expressions are utilized to calculate the RES data. Experimental results, obtained by an on-purpose arranged hardware-in-the-loop (HIL) rig, validate the sizing procedure
An Algebraic Algorithm for Motor Voltage Waveform Prediction in Dual-LCI Drives With Interconnected DC-Links
Full text linkLoad-commutated inverters (LCI's) are often used to supply dual-three-phase synchronous motors in high-power variable-speed applications. A pair of LCIs is used in this arrangement to feed the two motor three-phase winding sets. In order to cope with inter-harmonic issues, a drive configuration with an interconnection of the two LCI dc-links has been proposed. In this paper, such a drive design is shown to produce an increased voltage stress on motor windings compared with traditional configurations. The problem is investigated in the paper by proposing an algebraic algorithm capable of predicting the steady-state voltage waveform applied to the motor terminals and arising between the star points of the two winding sets. Unlike conventional dynamic simulations, the proposed approach gives practically instantaneous results, making it possible to quickly investigate a wide number of possible operating conditions. Furthermore, it requires a limited knowledge of system parameters, which are often hardly available. Its reliability and accuracy are assessed by comparison with measurements on a test drive system and examples are given of the method application to the sizing of motor insulation system
A flicker compensation strategy
No full textThis letter is concerned with the strategy adopted by an active compensator to mitigate the flicker phenomenon in a power system. After illustrating two conventional strategies, a novel strategy that forces the compensator to deliver a particular value of the instantaneous imaginary power absorbed by the time-variant load is proposed. The strategy is compared with the two conventional ones in terms of magnitude of the voltage fluctuations at the point of common coupling (PCC) and size of the capacitor in the dc bus of the active compensator. Suitable equations and vector diagrams are derived. They show that the novel strategy outweighs the other two by eliminating most of the PCC voltage fluctuations without the need for a large capacitor. The theoretical findings are substantiated by simulation results
Design and Comparison of Two Multilevel Converters for Flicker Compensation
No full textThe paper is concerned with the design of multilevel converters for compensating the flicker on the medium-voltage distribution networks. Two topologies of converters are considered, namely the Diode Clamped MultiLevel Converter (DCMLC) and the Cascade H-bridge MultiLevel Converter (CMLC). By analytical procedure, the current ratings for the semiconductor devices of the converters are determined, and their passive elements are sized up. The main outcome of the study is that the two topologies substantially require the same overall rating for the semiconductor devices, with the exception of the clamping diodes in the DCMLC-based topology. As a counterpart, the latter topology needs a lower overall capacitance
Dependability of safety-critical systems
No full textDependability, i.e. the capability of a system of delivering the expected service, is a fundamental requirement for safety-critical applications. It is becoming a very important matter in the automotive field. Indeed, car industries are planning to replace the traditional mechanical-hydraulic apparatus used for the execution of the driving commands with all-electric systems, the so-called drive-by-wire (DbW) systems, which are made of components that are not as reliable as the ones of the traditional apparatus. This paper, starting from the existing literature, provides at first a conceptual framework for the dependability topic. Then dependable architectures for DbW systems are presented. As a case of study, the steering maneuver is considered
In the eye of the beholder: Communicating CSR through color in packaging design
No full textConsumers have become much more attentive and demanding about corporate social responsibility (CSR), and companies are now gradually becoming aware that receiving consumer favor could depend on conducting business in a sustainable manner. Moreover, in order to gain returns from their CSR investments, such as company reputation, customer loyalty and customer–company identification, firms must also provide effective communication of their CSR efforts to the consumers. This study explores the potential of packaging color for conveying CSR to consumers, focusing in particular on consumer packaged goods. For this purpose, a quantitative study was conducted on a representative sample of consumers (n = 2000) in the form of a structured questionnaire, administered using face-to-face interviews. Three different stimuli were created through fictitious images of a nonexistent brand product. Only the color of the packaging varied, while all the other graphic elements were left unchanged. The results show that, despite the prevailing association of green with the concepts of sustainability and CSR, it is not the most suitable color to clearly and credibly convey a CSR message to consumers. Thus, it is important to examine whether different colors could serve better to improve the clarity and credibility of CSR claims
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