Characterization of Electromagnetic Device by Means of Spice Models

Abstract

— In this paper, the lumped parameter circuital approach devoted to the simulation of massive, conductive, and ferromagnetic cores including eddy currents and nonlinearity is presented. In the first part of the paper, the circuit analogies devoted to the simulation of magnetic structure coupled with external electrical and eventually mechanical equations are summarised. The two techniques are known in the literature as reluctance-resistance and permeancecapacitance analogies. In particular, it is put in evidence the exploitation of the gyrator component in the modelling of the coupling among magnetic and electrical quantities. The originality of this paper consists in demonstrating for the first time that the rotator-capacitor approach is very suitable for simulations in spice environment and the solution is validated on real applications. Following the circuital approach, the effect of the conductivity and nonlinear magnetic behaviour of the magnetic branches is formalized and introduced in the model. The simulation of the conductivity behaviour, which introduces in massive cores significant eddy current effects, is modelled according to the two possible analogies: the reluctance and the permeance-capacitor model. Under sinusoidal steady-state behaviour, energy aspects related to the two models are then presented and discussed. The nonlinearity is taken into account through the fixed-point technique which is suitable for a lumped circuit representation. The full circuital approach is then adopted for the simulation of the real electromechanical actuator under transient and sinusoidal steady-state behaviour conditions. The simulated result is then compared with numerical finite element and experimental result