APPARATUS FOR CONTROLLING DRIVE MOTOR FOR FEEDING ELECTRODE WIRE Russian patent published in 2003 - IPC

FIELD: gas-shield welding, namely semiautomatic machines for arc welding of thin-sheet metal by means of consumable electrode. SUBSTANCE: apparatus includes motor, source of welding electric current, pickup of motor emf value proportional to revolution number of motor, feedback circuit operating by counter-emf value. According to invention emf pickup of motor is in the form of diode detector and it includes diode whose cathode is connected with first inlet of motor and whose anode is connected with capacitor and resistor. Other terminal of capacitor is connected with second inlet of motor and with common conductor. Other terminal of resistor is connected to DC-source supplied from welding voltage source. Anode of diode is connected with inverting inlet of error signal amplifier having operational amplifier whose non-inverting inlet is connected with controlled DC-source. Outlet of error signal amplifier is connected with outlet of full-wave rectifier of welding electric current source. Other outlet of the last is connected with common conductor. Outlet of comparator is connected with inlet of electric current amplifier whose outlet is connected with first inlet of motor. To one inlet of comparator non-smoothed full-wave rectified voltage is fed and on other inlet of comparator control voltage from outlet of error signal amplifier is fed. Said comparator forms pulse-width modulator. EFFECT: enlarged range of controlling stabilized speeds of feeding electrode wire by means of simplified apparatus. 2 dwg