JPS6427786A - Power source controller for inverter type resistance welding machine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of damage on the titled controller by detecting a primary current of a welding transformer and comparing the variation of a pulse intermediate part and controlling a switching action of an inverter based on the comparison. CONSTITUTION:A current sensor 38 such as a troidal coil, etc., is provided to a primary coil of the welding transformer 20 having an inverter circuit 18 and connected to a primary current detection circuit 40 and a magnetic deflection detection circuit 42. An output signal of the sensor 38 is supplied to the circuit 40 which inputs the output signal SI to the magnetic deflection detection circuit 42. The circuit 42 produces a detected signal MS indicating a magnetic deflected state of the transformer 20 and a pulse control circuit 32 controls the switching action of the inverter circuit 18 so as to regulate the pulse width of the primary current Ip generated by a magnetic deflection phenomenon. By this method, the generation of an overcurrent based on the magnetic deflection phenomenon is eliminated and the occurrence of the damage on the controller is prevented.