Numerical waveform control for rotational single sheet testers

Abstract
Rotational single sheet testers are imposed as measuring systems for a complete, in plane, characterisation of magnetic materials. The numerical waveform control that drives the RSST is, despite its slow speed, more precise and versatile than the analogic version. Its adaptability to almost every induction waveform in a large frequency range makes it suitable for completely automated test procedures. The actual hardware implementations is reported. The existence of a variable coupling between the two principal axes imposes a simultaneous correction with respect to the flux waveform of the perpendicular axis. The magnetic circuit with airgaps hinders a simple direct relation between circuit and field equations, whence the difficulty of estimating the first correction steps. The electromagnetic model and the electrical equations are discussed in order to determine solutions that improve numerical convergence.