Shuki Wolfus | Bar-Ilan University (original) (raw)

Papers by Shuki Wolfus

IEEE Transactions on Applied Superconductivity, Aug 1, 2023

Review of Scientific Instruments, Jun 1, 2019

IEEE Transactions on Applied Superconductivity, Dec 1, 2018

We explore the effects of various receiver coil dimensions and configurations on power transfer e... more We explore the effects of various receiver coil dimensions and configurations on power transfer efficiency and cost of operation, using advanced simulation tools. We demonstrate that the spatial distribution of the magnetic field leads to a non-monotonic dependence of the coupling coefficient on coil size. Thus, an optimal coil size, where the coupling coefficient peaks, should be regarded a crucial design parameter which affects the entire system performances. The incorporation of our findings into a multi-objective optimization algorithm is also discussed.

The saturated cores FCL exhibits several attractive technological advantages: inherent fail-safe ... more The saturated cores FCL exhibits several attractive technological advantages: inherent fail-safe and selectivity design, superconductivity is maintained during both nominal and fault states, the limiting process as well as the recovery after fault are passive and immediate, operation in limiting state is not time-limited, and the superconducting bias coil is made of wires available as commercial shelf-product. Despite these advantages, saturated cores FCL did not make it to commercial phase because of the large volume and heavy weight associated with its realization, a coupling problem between the AC and bias coils while in limiting state, and non-optimal limitation resulting from the presence of the bias field during fault. This work presents a novel, improved saturated cores FCL concept that overcomes the above difficulties and reopens the possibility for commercialization. Unique design topography reduces the cores volume and at the same time reduces the AC and DC magnetic coupling to about 2%. In addition, a control circuit, triggered by voltage drop across the FCL terminals, is added and disconnects the bias coil during a fault for increased limiting performances. All above-mentioned advantages of the saturated cores concept are maintained in this new design. First, a 4.2 kVA laboratory scale FCL has been designed built and studied proving the feasibility of the new design. Then, an up-scaled, 120 kVA model has been designed, built and tested at the testing laboratory of the Israel Electric Company. The prospective short current in the test bed was 5000 A, successfully limited to 2400 A. The 120 kVA model is a single phase FCL designed for 400 V, 300 A nominal conditions. Core losses and AC coils losses are 0.09% and 0.18%, respectively.

Physical Review Letters, 1997

PLoS Computational Biology, 2011

Physical Review Letters, 1996

IEEE Transactions on Appiled Superconductivity, 2003

Skin Research and Technology, 2010

2017 Electric Vehicles International Conference (EV), 2017

Optimizing the efficiency of primary and secondary coil configurations for Dynamic Wireless Power... more Optimizing the efficiency of primary and secondary coil configurations for Dynamic Wireless Power Transfer (DWPT) in Electric Vehicles (EVs) requires means for accurate calculation of the mutual inductance in an array of coils. Based on finite element simulation method, we present a quick and accurate method for calculating the energy transfer capabilities of a given DWPT array. By consecutively switching on and off every coil and driving them with a constant current ramp rate, mutual inductances and a coupling coefficient matrix of the whole configuration is easily calculated. This method allows for relatively easy optimization and up-scaling of DWPT systems to multiple arrays of primary and secondary coils as well as implementing various coil designs and configurations. The data acquired using this method may also be used during real-time applications providing indications of vehicle relative alignment.

Energies

Designs of saturated-cores fault current limiters (FCLs) usually implement conducting or supercon... more Designs of saturated-cores fault current limiters (FCLs) usually implement conducting or superconducting DC coils serving to saturate the magnetic cores during nominal grid performance. The use of coils adds significantly to the operational cost of the system, consuming energy, and requiring maintenance. A derivative of the saturated-cores FCL is a design implementing permanent magnets as an alternative to the DC coils, eliminating practically all maintenance due to its entirely passive components. There are, however, various challenges such as the need to reach deep saturation with the currently available permanent magnets as well as the complications involved in the assembly process due to very powerful magnetic forces between the magnets and the cores. This paper presents several concepts, achieved by extensive magnetic simulations and verified experimentally, that help in maximizing the core saturation of the PMFCL (Permanent Magnet FCL), including optimization of the permanent ...