Magnetization–demagnetization – numerical solution and movie. The ferromagnetic core...

Magnetization–demagnetization – numerical solution and movie. The ferromagnetic core of the circuit shown in Fig.5.4(a) has the cross-sectional area S = 1 cm2, mean length l = 20 cm, and air-gap thickness l0 = 1 mm. The number of wire turns of the coil is N = 1000, the resistance of the winding is R = 20 Ω, and the emf of the

generator is E = 20 V. The core does not have residual magnetization and the switch K is in the off position (open). By turning the switch on, the mmf is applied to the circuit and the magnetic flux through it rises following the initial magnetization curve of the material. This curve can be considered as linear, as shown in Fig.5.4(b), where the initial permeability is μ_a = 0.001 H/m (B = μ_aH). The magnetic flux density in the core becomes B = B_m in the stationary state. The switch is then turned off (opened) and a new stationary state established in the circuit.

The demagnetization curve for the material can be approximated by two straight-line segments [Fig.5.4(b)], where Hc (coercive force) equals Hm. In MATLAB, make a movie that simulates the magnetization–demagnetization of the circuit in the B-H diagram in Fig.5.4(b). (ME5 14.m on IR)