Frequency dependence of hysteresis loss in YBCO tapes

Abstract

We measured the frequency dependence of hysteresis loss in non-striated and striated YBCO coated conductors in the frequency range from 1 mHz up to 350 mHz at 77 K. At these frequencies the coupling losses in YBCO coated conductors do not exist and in filamentary YBCO tapes they can be practically neglected. The dominant loss component is the hysteresis loss. We have found that for magnetic fields above the full penetration field the hysteresis loss increases with increasing frequency and this dependence can be described by a power law function. For magnetic fields below the penetration field the hysteresis loss decreases with frequency. This behaviour supports the previous theoretical results indicating that the field dividing the behaviour of hysteresis losses versus frequency is the penetration field. The experiments with YBCO samples on non-metallic substrate at frequencies up to 600 Hz show that the dependence of hysteresis losses measured at millihertz frequencies can be extrapolated to higher frequencies of the order of 100 Hz. We propose a simple procedure to separate the hysteresis losses from the total measured losses based on the measurement of the frequency dependence of losses at low frequencies. Taking into account the frequency dependence of hysteresis losses we can considerably reduce the errors in the separation of hysteresis losses from the total measured losses.

Ripple field losses in direct current biased superconductors: Simulations and comparison with measurements

“…For a fixed n-value, the lower the frequency, the higher the losses. The measurements, e.g., in 48,52 do support this kind of behaviour, but not to this extent, even though the discrepancy is not enormous. The frequency-dependence of the hysteresis losses is reduced, as the model is modified towards CSM by increasing the n-value To make a thorough comparison of the models in ripple field loss simulations, we performed a set of simulations with different combinations of DC field, DC current and AC field for a coated conductor tape with cross-section dimensions 4 mm × 1 µm.…”

Magnetization loss for stacks of ReBCO tapes

“…Using the minor loops measurements the magnetization loss of the stacks (see description in table 1) is calculated at 5 K and 77 K as an area of the closed loop: Q = m dB a . A minor effect of the ramp rate on the loss was found and could be expressed as Q ∼Ḃ 1/n [21]. This relation can be simply obtained from the equation (5) if the sample is considered only in the saturated state (good assumption for the samples with a low penetration field).…”

Effect of Selectively Electrodeposited Stabilizer Thickness on AC Loss Behavior of Fully-Filamentized HTS Wire

“…Frequency dependence AC loss characterization can provide more information but, there is limited data and interpretation differs in the literature [9], [12], [13]. Plots of AC loss per cycle, [mJ/m/cycle], of all seven samples as a function of frequency at four different field amplitudes are presented in Fig.…”

“…In order for HTS coated conductors to be employed in AC field applications, such as transformers, motors and fault current limiters, the relatively dominant hysteretic loss generated by the AC field due to the high aspect ratio in HTS CCs has to be addressed. Filamentization of the superconductor layer has been pursued with great interest for reduction of AC losses and many techniques been have evaluated [3]- [9]. Brandt and Indenbom [10] have derived an expression for hysteretic losses in presence of applied AC field, H a , perpendicular to wire the flat surface where x = πH a w/I c , f is frequency, w is the width of the filament (or tape width for non-striated samples), I c is the critical current, and μ 0 is the permeability of free space.…”