AC power source voltage regulator including outward voltage slope control

Claim 2

An AC power source voltage regulator comprising a. a welding transformer, b. a thyristor connected in series with the primary of said welding transformer, c. a phase shift circuit connected to an AC power source in parallel with said primary of said welding transformer to provide an output of a phase that leads the phase of said power source, d. a filter for passing an AC portion of the phase shifted output of said phase shift circuit within the frequency range below a predetermined upper cutoff frequency, e. means providing a DC reference voltage, and a comparator for comparing the phase shifted AC output of said filter with said DC reference voltage and for providing an output signal if and only if the output of said filter is less than said DC voltage, f. a circuit for generating an output pulse in response to the output signal of said comparator, and means applying said output pulse to trigger said thyristor, and g. a slope regulating circuit connected to said circuit for generating an output pulse for controlling the width of said output pulse of said pulse generating circuit.

Claim 3

A device for compensating the variation in AC power source voltage as defined in claim 1 wherein said pulse generator comprises a unijunction transistor, an output pulse transformer connected in series with one of the bases of said unijunction transistor, a first capacitor connected between the emitter of said unijunction transistor and said pulse transformer, a first transistor having its collector and emitter interconnected with said second capacitor, and a second thyristor having its anode and cathode connected to the base and emitter of said first transistor, respectively, said second thyristor being connected to be triggered in response to the output of said comparator; and said slope regulating circuit comprises a resistor, a second transistor having its collector connected through said resistor to said first capacitor for charging the same, a timer, a variable resistor inserted between the base of said second transistor and said capacitor connected between the base and emitter of said secOnd transistor.

Claim 4

In an AC voltage regulator for a welding system of the type having a welding transformer with a primary winding, AC input terminals, and controlled rectifier means connected in series between said primary winding and said input terminals, said controlled rectifier means having a control terminal; the improvement comprising phase shift means connected to said terminals for providing an AC voltage of a phase leading the phase of voltage at said terminals, low pass filter means connected to filter said phase shifted voltage, and to provide a frequency limited phase shifted AC voltage, reference voltage terminals providing a DC reference voltage, means comparing said DC voltage at said voltage terminals with the frequency limited phase shifted AC voltage output of said filter means and providing an output signal if and only if the output of said filter is less than said DC voltage, pulse generator means responsive to said signal from said comparing means for providing a pulse output, means applying said pulse output to said control terminal whereby the conduction angle of the controlled rectifier may be varied inversely with the voltage at the AC input terminals, and slope regulating means connected to said pulse generator means for further controlling the width of pulses of said pulse output.

Claim 5

In an AC voltage regulator for a welding system of the type having a welding transformer with a primary winding, AC input terminals, and controlled rectifier means connected in series between said primary winding and said input terminals, said controlled rectifier means having a control terminal; the improvement comprising phase shift means connected to said terminals for providing an AC voltage of a phase leading the phase of voltage at said terminals, low pass filter means connected to filter said phase shifted voltage, and to provide a frequency limited phase shifted AC voltage, reference voltage terminals providing a DC reference voltage, means comparing said DC voltage at said voltage terminals with the frequency limited phase shifted AC voltage output of said filter means and providing an output signal if and only if the output of said filter is less than said DC voltage, pulse generator means responsive to said signal from said comparing means for providing a pulse output, means applying said pulse output to said control terminal whereby the conduction angle of the controlled rectifier may be varied inversely with the voltage at the AC input terminals, and slope regulating means connected to said pulse generator means for further controlling the width of pulses of said pulse output.