Shunt A.C. voltage regulator with modified full-wave bridge

A voltage regulator for a current limited A.C. voltage source comprising:

• a semiconductor switching device having a pair of power electrodes and a control electrode;
• means for connecting the switching device by its power electrodes in shunt with the voltage source;
• means for connecting a load in shunt with said switching device;
• a full-wave bridge rectifier, a first node of which is connected to one of said power electrodes and a second node of which is connected to the other of said power electrodes, said first and second nodes being located diagonally opposite each other in said rectifier, said rectifier including
• a first diode, one electrode of which is connected to said first node,
• a first impedance means connected in series between the other electrode of said first diode and a third node of the rectifier,
• a second diode, one electrode of which is connected to said second node,
• a second impedance means connected in series between the other electrode of said second diode and said third node,
• a third impedance means interconnecting the junction of said first diode and said first impedance means with the junction of said second diode and said second impedance means,
• a third diode connected between said first node and a fourth node,
• a fourth diode connected between said second node and said fourth node,
• control circuit means connected across said third node and said fourth node of said bridge rectifier and responsive to the voltage impressed across said third and fourth nodes for applying a control signal to the control electrode of the switching device to thereby cause the switching device to become conductive when the potential across its power electrodes is of the proper polarity, said control circuit means including
• a capacitor connected across the third and fourth nodes of said bridge rectifier,
• a semiconductor avalanche device,
• means connecting the avalanche device across said capacitor to cause said avalanche device to switch to the low impedance state when the charge on the capacitor attains a level equal to the avalanche voltage of the avalanche device, and
• means responsive to said avalanche device switching to the low impedance state for applying a control signal to the control electrode of the switching device.

A voltage regulator for an A.C. voltage source comprising

• a semiconductor switching device having a pair of power electrodes and control electrode,
• means for connecting the switching device by its power electrodes in shunt with said voltage source,
• means for connecting a load in shunt with said switching device,
• a full-wave bridge rectifier coupled by a first pair of diagonally opposite nodes in shunt with the voltage source,
• a capacitor coupled across a second pair of diagonally opposite nodes of the rectifier,
• first impedance means connected in said bridge rectifier for controlling the charge rate of said capacitor,
• a transistor whose emitter-collector circuit is coupled in series between one plate of said capacitor and the control electrode of the switching device,
• a semiconductor avalanche device coupled between the other plate of said capacitor and the base of said transistor, and
• second impedance means coupled between the base and the emitter of said transistor,
• said avalanche device being switched to a low impedance state when the charge on the capacitor attains a level equal to the avalanche voltage of the of the avalanche device permitting flow of current to bias the transistor to a more conductive state and apply a current thru the emitter-collector circuit of the transistor to the control electrode of the switching device causing the switching device to switch to the low impedance state when the voltage across its power electrode is of the proper polarity.