High frequency extension of non-linear models of laminated cores
Purpose - The 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/approach - High 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 (mu) and the electric conductivity (sigma). Findings - For small signals high frequency field components, the laminated steel behaviour can be described by two local parameters (mu, sigma) and skin effect. The values of mu and sigma do not depend on frequency up to 1 MHz, but only on the operating point. Research limitations/implications - The proposed broadband characterisation should be associated with a Priesach model that defines the operating point for computer simulation of high frequency phenomena. Practical implications - The broadband characterisation of magnetic laminations is useful for studying the behaviour of the windings of the PWM-fed machines. Originality/value - Broadband measurements are now possible on small magnetic steel lamination samples.
laminates magnetic measurement non-linear control systems