The invention concerns the control of thyristor-type semiconductor power components (Sw) powered by an alternating current network (VS). The control signal is a pulse (Ie). It is stored in the form of magnetic induction (B), positive or negative, in a core (T) made of ferromagnetic material. At each current alternation of the network, the interrogation of the magnetic state of the strand results in the presence, or not, of a control signal on the power device (Sw).