1,721,058 research outputs found
Frequency tuning in inductive power transfer systems
Full text linkInductive power transfer systems (IPTSs) systems are equipped with compensation networks that resonate at the supply frequency with the inductance of the transmitting and receiving coils to both maximize the power transfer efficiency and reduce the IPTS power sizing. If the network and coil parameters differ from the designed values, the resonance frequencies deviate from the supply frequency, thus reducing the IPTS efficiency. To cope with this issue, two methods of tuning the IPTS supply frequency are presented and discussed. One method is aimed at making resonant the impedance seen by the IPTS power supply, the other one at making resonant the impedance of the receiving stage. The paper closes by implementing the first method in an experimental setup and by testing its tuning capabilities on a prototypal IPTS used for charging the battery of an electric vehicle
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
Analysis and experimentation of a novel modulation technique for a dual-output WPT inverter
Full text linkDynamic wireless power transfer systems require to supply many transmitting coils deployed under the road surface and arranged along the so-called track. This layout entails the use of a large number of inverters or of devices that switch the power to the proper coils. This paper presents a technique that uses a single three phase inverter to supply two coils with voltages having different and independently adjustable amplitudes of their first harmonic component. Differently from the well-known phase shift technique, the amplitude and the phase of the voltages are not correlated. Moreover, the presented technique has the ability of inherently reducing the phase difference between the two output currents when the supplied loads are partially reactive. This feature enhances the power transfer capability of the inverter when both the track coils are coupled with the same pickup. After presenting this technique, the paper analyzes the functioning of the dual-output inverter in different load conditions recognizing the boundaries of four different modes of operation. For each of them the analytical expression of the amplitude and phase of the generated voltages are given. The theoretical findings are validated by experiments performed on a prototypal setup that implements the presented modulation technique
Avoiding Null Power Point in DD coils
No full textDD coils are one of the most used coupling arrangements for the tracks and the pickups in dynamic wireless power transfer system. They reach a higher coupling coefficient with respect to conventional coil pairs with the same dimensions and assure a more effective and efficient power transfer to the electric vehicles. On the other hand, DD coils suffer of the phenomenon known as null power point, by which the power transferred to the pickup, is zero even if it is still partially coupled to the transmitting track coil. The null power points are typically removed by installing the so-called Q coil in the pickup. The power transferred to the Q coils is added to that harvested by the DD coil by a separate power converter so that the overall architecture of the receiving side of the dynamic wireless power transfer system results rather intricate. This paper presents a different approach to the problem of the null power points, based on the switching between two different supplying modes of the track DD coils. In front of a more complex architecture of the power supply system of the track, this approach gets rid of the Q coil and of the relevant power converter. The proposed solution is at first studied analytically with an approximated model of the DD coils and then verified by means of a FEM analysis and simulation
Dual-output inverter with phase correction ability for dynamic WPT track supply
Full text linkDynamic WPT systems are extensively investigated as a promising solution to the issues of the comparatively short range and long recharge time of the electric vehicles. In dynamic WPT systems, the lumped tracks exhibit greater power transfer efficiency than the stretched ones but require the supply of a large number of transmitting coils. This paper proposes a command strategy for a dual-output inverter that allows the concurrent supply of two track coils, with the ability of adjusting independently the voltage applied to each of them without altering the phase relation between the two supply currents. Moreover, if the series resonant compensation is used at the track side, the proposed strategy is robust against the onset of a reactive component in the loads seen at the inverter outputs as it inherently corrects the phase of the coil currents without making recourse to any additional control algorithm
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
Energy Management System for DC Electric Spring with Parallel Topology
No full textDC electric spring (DCES) maintains the voltage stability and improves the power quality in dc microgrid with the inclusion of renewable energy sources. A parallel DCES topology has been recently proposed; it consists of a dc-dc three-port converter and an energy storage system made up of a battery paralleled with the critical load (CL) through a bidirectional buck-boost converter. In this article, an effective energy management system (EMS) is proposed for the parallel DCES topology. After illustrating the DCES operating modes, three functional states are introduced, namely normal, specific time, and emergency, where the normal state refers to the DCES operation under dc microgrid power fluctuations, whereas the specific time and emergency states refer, respectively, to the environment conditions and battery contingent situations. The EMS decides the transitions between the DCES operating modes, changes the operating status of the battery, and realizes multiple charging and discharging mechanism. This gives DCES the capabilities of guaranteeing the voltage stability of CL while keeping the state of charge of the battery within a reasonable range, which extends the lifetime of battery and ensures safe and reliable operation of the whole system. The proposed EMS has been validated by simulation and experimental results
Familial cardiomyopathy associated with right bundle branch block, ST segment elevation and sudden death - Reply
No full textPacemaker indication in patients with complete a-v bloch following orthotopic heart transplantation
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