Design and Uncertainty Analysis of an AC Loss Measuring Instrument for Superconducting Magnets

A novel instrument was designed and numerically validated for measuring AC losses in ramped superconducting magnets. These power losses are expected to be in the 1 W to 100 W range. The instrument improves metrological performance compared to existing instruments by reaching a target power loss uncertainty in the order of 0.1 watt. This allows accurate measurement of the power losses to improve magnet modeling. A Monte Carlo analysis is used to evaluate the measurement uncertainty. Such an analysis addresses the lack of uncertainty investigation in the literature for this kind of measurement, and the proposed approach can be applied to various magnet models. The physical design of the instrument is carried out by relying on an FPGA-based acquisition platform. Results on a representative case study reveal that the target uncertainty can be reached without any compensation or correction mechanism. Instead, when aiming to use compensation or correction of the inductive magnet voltage, the sensitivity analysis points out that offset errors and time delays must be limited. This also suggests that the magnet’s inductance estimation should be improved more than the metrological performance of the instrumentation.