A Study on Superconducting Coils for Superconducting Magnetic Energy Storage (SMES) Applications

Part 15: Energy TransformationInternational audienceSuperconducting coils (SC) are the core elements of Superconducting Magnetic Energy Storage (SMES) systems. It is thus fundamental to model and implement SC elements in a way that they assure the proper operation of the system, while complying with design specifications. As a part of a larger model, a coil design model is here presented and verified with tests made in a laboratory prototype. The limitations of the superconducting tape used, namely the negative effect of magnetic field components on its critical current value, are also verified and a possible solution to avoid that effect is studied

Study of AC losses in medium-sized high temperature superconducting coils

The study of AC losses in superconducting pancake coils is of utmost importance for the development of superconducting devices. Due to different technical difficulties this study is usually performed considering one of two approaches: considering superconducting coils of few turns and studying AC losses in a large frequency range vs. superconducting coils with a large number of turns but measuring AC losses only in low frequencies. In this work, a study of AC losses in 128 turn superconducting coils is performed, considering frequencies ranging from 50 Hz till 1152 Hz and currents ranging from zero till the critical current of the coils. Moreover, the study of AC losses considering two different simultaneous harmonic components is also performed and results are compared to the behaviour presented by the coils when operating in a single frequency regime. Different electrical methods are used to verify the total amount of AC losses in the coil and a simple calorimetric method is presented, in order to measure AC losses in a multi-harmonic context. Different analytical and numerical methods are implemented and/or used, to design the superconducting coils and to compute the total amount of AC losses in the superconducting system and a comparison is performed to verify the advantages and drawbacks of each method

Transport AC Loss Measurements of a Triangular, Epoxy-Impregnated High Temperature Superconducting (HTS) Coil

In this paper, the transport AC losses in a triangular, epoxy-impregnated high temperature superconducting (HTS) coil made from YBCO coated conductor, intended for use in a prototype axial flux HTS electric machine, are measured using two different electrical techniques at 77 K. The first set of AC loss measurements of the coil are carried out at the University of Cambridge using a technique based on a lock-in amplifier. The coil is then measured at the Center for Advanced Power Systems (CAPS), Florida State University, using a technique based on a high accuracy data acquisition (DAQ) measurement system. The two different methods show consistent results, validating the accuracy of these two techniques for transport AC loss measurements of superconducting coils. Multiple voltage taps are utilized within the coil to study the details and distribution of the AC loss in different sections of the coil. Losses are also measured with a flux diverter made of ferromagnetic material to analyze its effect on the AC losses.The work of D. Hu was supported by Churchill College, the China Scholarship Council, and the Cambridge Commonwealth, European and International Trust. The work of M. D. Ainslie was supported by a Royal Academy of Engineering Research Fellowship

Architecture, Voltage and Components for a Turboelectric Distributed Propulsion Electric Grid

The development of a wholly superconducting turboelectric distributed propulsion system presents hide unique opportunities for the aerospace industry. However, this transition from normally conducting systems to superconducting systems significantly increases the equipment complexity necessary to manage the electrical power systems. Due to the low technology readiness level (TRL) nature of all components and systems, current Turboelectric Distributed Propulsion (TeDP) technology developments are driven by an ambiguous set of system-level electrical integration standards for an airborne microgrid system (Figure 1). While multiple decades' worth of advancements are still required for concept realization, current system-level studies are necessary to focus the technology development, target specific technological shortcomings, and enable accurate prediction of concept feasibility and viability. An understanding of the performance sensitivity to operating voltages and an early definition of advantageous voltage regulation standards for unconventional airborne microgrids will allow for more accurate targeting of technology development. Propulsive power-rated microgrid systems necessitate the introduction of new aircraft distribution system voltage standards. All protection, distribution, control, power conversion, generation, and cryocooling equipment are affected by voltage regulation standards. Information on the desired operating voltage and voltage regulation is required to determine nominal and maximum currents for sizing distribution and fault isolation equipment, developing machine topologies and machine controls, and the physical attributes of all component shielding and insulation. Voltage impacts many components and system performance