High frequency extension of non‐linear models of laminated cores

Abstract

PurposeThe paper gives a new measurement method of the parameters characterising the magnetic laminations for broadband low‐level signals defined at any operational point.Design/methodology/approachHigh frequency phenomena machines fed by PWM inverters are related to low‐level signals corresponding to minor hysteresis loops around the instantaneous working point, which moves on the main loop at the basic frequency. The minor loops are assimilated to ellipses, which are characterised by only two parameters: the incremental magnetic permeability (μ) and the electric conductivity (σ).FindingsFor small signals high frequency field components, the laminated steel behaviour can be described by two local parameters (μ, σ) and skin effect. The values of μ and σ do not depend on frequency up to 1 MHz, but only on the operating point.Research limitations/implicationsThe proposed broadband characterisation should be associated with a Priesach model that defines the operating point for computer simulation of high frequency phenomena.Practical implicationsThe broadband characterisation of magnetic laminations is useful for studying the behaviour of the windings of the PWM‐fed machines.Originality/valueBroadband measurements are now possible on small magnetic steel lamination samples.