FREQUENCY CONVERTER FOR THE STABILIZED SUPPLY OF ASYNCHRONOUS MOTORS

摘要

The frequency converter for the supply of an asynchronous motor comprises: a rectifier bridge (11) connected to a polyphased network and to an intermediary circuit (12) of direct voltage; an invertor (13) comprising three pairs of static switches (T1, T6) mounted with a Graetz bridge configuration; characterized by: a current reading member (21) associated to the intermediary circuit (12) elaborating an image signal of the inverse current and delivering an image signal of the current in this circuit; a stabilization control circuit (22) connected to said member (21) and delivering an inverse current excess signal (ST) when the signal (Id) exceeds an adjustable threshold; and means (25) for reducing the output voltages of the invertor capable of modifying the modulated pulses, said means being controlled by the output signal (ST) of the stabilization control circuit (22).