THE SAFE THREE-PHASE CONTAC-FREE SWITCH

The safe contact-free switch (BS) for the control of an asynchronous three-phase motor (M) has three input phase voltages of phases (R1S1T), which are mutually galvanic separated by the transformer (TR), and the three output phase voltage of phases (R', S', T'), whose common node (N') is created by connection of the respective output from sources of individual voltages of phases (R', S', T'), whose sinusoidal voltages and currents, entering into the three-phase asynchronous motor (M), have the frequency of the supply system. The source of the voltage of phase (R') is a controlled first bridge inverter (MS1). The source of voltage of phase (S') is a controlled second bridge inverter (MS2). The source of voltage of phase (T') is secondary winding of the transformer (TR) of the phase (T). The common node (N') of individual phases (R', S', T') of the output of safe three-phase contact-free switch (BS) is created after behind the controlled bridge inverters (MS1, MS2). At least two phases (R, S) are connected to the respective controlled bridge rectifiers (MU1, MU2), whose outputs are connected to the respective controlled bridge inverters (MS1, MS2). The frequency of switching of rectifiers (MU1, MU2) and inverters (MS1, MS2) is identical with the frequency of input phase voltages of phases (R1S1T). Each of at least two phases (R1S) of voltage is connected to the controlled bridge rectifier (MU1 , MU2) through the reactor-coil (TL1 , TL2). Between the outputs of the controlled bridge rectifiers (MU1, MU2) there are the anti-snubber members (PZC1, PZC2). Between the outputs of the controlled bridge rectifiers (MU1, MU2) and inputs of the controlled bridge inverters (MS1, MS2) for each input phase (R, S), is created an independent DC semi-circuit, which do not contain components for accumulation of energy. L'invention concerne un commutateur sans contact (BS) sûr qui permet de commander un moteur triphasé asynchrone (M) et qui comprend trois tensions d'entrée de phases (R1S1T) mutuellement séparées par galvanisation par le transformeur (TR) et trois tensions de sortie de phases (R', S', T'), dont le noeud commun (N') est créé par la connexion de la sortie respective des sources des tensions de phases individuelles (R', S', T'), dont les tensions et les courants sinusoïdaux, entrant dans le moteur asynchrone triphasé (M), présentent la fréquence du système d'alimentation. La source de la tension de phase (R') est un convertisseur de premier pont commandé (MS1). L